A TCL agradece o apoio do Royal Society Research Grant 2016 R1 (RG150551) e do Prêmio líder futuro da UCL BEAMS financiado através do prêmio de Patrocínio Institucional da EPSRC (EP/P511262/1). WiKC, TCL e IPP agradecem ao Studentship financiado pelo Programa de Anexo de Pesquisa A*STAR-UCL através do CDT EPSRC M3S (EP/L015862/1). A GD e a TJ agradecem ao CDT EPSRC M3S (EP/L015862/1) pelo patrocínio de sua discuagem. TJ e TCL reconhecem a Camtech Innovations por contribuição ao ensino do TJ. Todos os autores são gratos ao Fundo de Acesso Aberto da UCL.

1. Síntese de Au NPs
<ol><li>Síntese de sementes de Au através do método turkevich convencional26<ol>
<li>Prepare 10 mL de solução HAuCl4 de 25 mM dissolvendo 98,5 mg de HAuCl4· 3H2O precursor com 10 mL de água deionizada em um frasco de vidro. NOTA: Transfira uma pequena quantidade de precursor do HAuCl4 em um barco de pesagem e use uma espátula de plástico em vez de espátula metálica para pesar os cristais porque o precursor HAuCl4 irá corroer o labware metálico. A etapa de pesagem deve ser realizada o mais rápido possível, uma vez que o HAuCl4 é higroscópico e, portanto, aumentará seu peso ao longo do tempo absorvendo água da atmosfera. O HAuCl4 é altamente corrosivo e pode causar queimaduras graves na pele e danos nos olhos. Tome cuidado extra ao manuseá-lo.</li>
		<li>Prepare 0,5 mL de solução de citrato de sódio de 500 mM dissolvendo 64,5 mg de pó de citrato de sódio com 0,5 mL de água desionizada em um frasco de vidro.</li>
		<li>Diluir 1 mL da solução HAuCl4 de 25 mM com água de 99 mL em uma garrafa de tampa azul de 250 mL para dar 100 mL de solução HAuCl4 de 0,25 mM.</li>
		<li>Adicione 99,5 mL da solução HAuCl4 de 0,25 mM em um frasco de três pescoços de três pescoços equipado com um condensador. Aqueça a solução a 90 °C sob agitação vigorosa e mantenha a temperatura por 15 minutos.</li>
		<li>Injete 0,5 mL da solução de citrato de sódio de 500 mM na mistura de reação e mantenha a temperatura e mexendo até que a cor da solução fique vermelho-rubi. NOTA: A reação leva cerca de 30 minutos.</li>
	</ol></li>
	<li>Crescimento semeado de NPs Au através do método cineticamente controlado13
	<ol>
<li>Esfrie a solução de sementes Au sintetizada a 70 °C.</li>
		<li>Prepare 10 mL de solução citrato de sódio de 60 mM dissolvendo 154,8 mg de pó de citrato de sódio com 10 mL de água desionizada em um frasco de vidro.</li>
		<li>Injete 0,67 mL da solução de 25 mM HAuCl4 e 0,67 mL da solução de citrato de sódio de 60 mM para as sementes de Au com intervalo de tempo de 2 min.</li>
		<li>Repita o passo 1.2.3 para aumentar gradualmente o tamanho de Au NPs para 40 nm. NOTA: É preciso cerca de 10 passos de crescimento para chegar a 40 nm. O número real de etapas necessárias pode depender da configuração precisa.</li>
	</ol></li>
	<li>Crescimento semeado de NPs Au usando sintetizador automatizado (Figura 2)
	<ol>
<li>Transfira 25 mL da solução de sementes Au preparada na seção 1 para um tubo de centrífuga cônica de 50 mL e esfrie a 70 °C em um termomixer. NOTA: Monitore a temperatura dentro do termomixer usando um termômetro termopar colocado em um tubo de centrífuga de 50 mL contendo 25 mL de água.</li>
		<li>Encha uma seringa descartável Luer de 3 mL com 2,5 mL de solução HAuCl4 de 25 mM. Encha outra seringa descartável luer de 3 mL com 2,5 mL de solução de citrato de sódio de 60 mM.</li>
		<li>Coloque as seringas nas bombas de seringa e use adaptadores Luer-to-MicroTight para conectar o tubo PEEK (150 μm de diâmetro interno) às seringas. Insira a tubulação no tubo centrífuga contendo a solução de sementes de Au no termomixer.</li>
		<li>Coloque ambas as bombas de seringa para dispensar 0,1675 mL de solução acima de 20 min (8.357 μL por minuto).</li>
		<li>Defina a velocidade de rotação do termomixer para 700 rpm e pressione Inicie a bomba de seringa contendo a solução HAuCl4 de 25 mM.</li>
		<li>Após 2 min, pressione Inicie a bomba de seringa contendo a solução de citrato de sódio de 60 mM.</li>
		<li>30 min após iniciar a injeção da solução HAuCl4 , remova uma alíquota da solução Au NP para análise.</li>
		<li>Repetir as etapas 1.3.5 – 1.3.7 para aumentar gradualmente o diâmetro dos Au NPs até 40 nm. NOTA: Esta configuração pode ser usada para crescer NPs Au até 40 nm em um passo, aumentando o volume de reagentes adicionados na etapa 1.3.4. Isso é conseguido aumentando o tempo de dispensação, mantendo a mesma taxa de injeção.</li>
	</ol></li>
</ol>2. Caracterização de NPs Au
<ol><li>Espectroscopia UV-Vis<ol>
<li>Adicione 1 mL da solução Au NP a um cuvette de quartzo semi-micro.</li>
		<li>Ligue o espectrômetro.</li>
		<li>Defina o comprimento de onda para 400 - 800 nm.</li>
		<li>Adquira o espectro UV-Vis para cada amostra.</li>
	</ol>
</li>
	<li>Dispersão dinâmica de luz (DLS)<ol>
<li>Filtre a solução amostral em uma cuvette semi-micro de plástico com um filtro de 0,22 μm.</li>
		<li>Ligue o instrumento DLS.</li>
		<li>Coloque a temperatura em 25 °C e equilibre para 60 s.</li>
		<li>Meça o tamanho hidrodinâmico de cada amostra.</li>
	</ol>
</li>
	<li>Microscopia eletrônica de transmissão (TEM)<ol>
<li>Coloque uma gota de 5 μL da solução de amostra em uma grade revestida de 300 malhas C e seque no ar. NOTA: A diluição é necessária para amostras de solução Au NP mais concentradas para obter NPs Au bem dispersos em uma grade TEM.</li>
		<li>Adquira várias imagens TEM para cada amostra usando um TEM a 200 kV de aceleração.</li>
		<li>Meça o diâmetro de 200 NPs Au para cada amostra usando ImageJ para calcular o tamanho médio e o desvio padrão.</li>
	</ol>
</li>
</ol>3. Formação de complexos CB7-UA
<ol><li>Preparação da solução CB7 de 0,4 mM<ol>
<li>Adicione 4,65 mg de CB7 a um frasco de vidro de 15 mL. NOTA: O valor do CB7 é calculado com base no peso da fórmula de CB7 (= 1163 Da) que tem sido empregado pela maioria dos relatórios na literatura. No entanto, as amostras sólidas cb7 normalmente contêm água, HCl, metanol e outros sais deixados a partir das etapas de síntese e purificação, contribuindo para ~10 – 20% de peso morto na amostra. Os solventes e sais presos não puderam ser removidos por aquecimento em um forno a vácuo ou outros meios. Suas quantidades variam entre diferentes lotes de amostras, mas podem ser quantificadas por meio de análise elementar. No entanto, o protocolo apresentado não é sensível à presença de quantidade não quantificada de solventes e sais nas amostras do CB7.</li>
		<li>Adicione 10 mL de água ao frasco e aperte a tampa.</li>
		<li>Sonicar a amostra à temperatura ambiente até que o sólido CB7 seja completamente dissolvido. NOTA: O CB7 foi sintetizado de acordo com a literatura27 , mas também está disponível comercialmente.</li>
	</ol>
</li>
	<li>Preparação de solução UA de 0,4 mM<ol>
<li>Adicione 2,69 mg de UA a um tubo de centrífuga de 50 mL.</li>
		<li>Adicione 40 mL de água ao tubo e aperte a tampa.</li>
		<li>Use um termomixer para rodar a solução amostral, definindo a temperatura para 70 °C, velocidade de 800 rpm e tempo para 2h. Deixe a solução esfriar até a temperatura ambiente. NOTA: A UA tem baixa solubilidade na água (0,40 mM)5. Gire por mais tempo se o pó UA não tiver sido completamente dissolvido. Alternativamente, a ultrassonização pode ser usada para facilitar a dissolução.</li>
	</ol>
</li>
	<li>Diluições sequenciais da solução UA de 0,4 mM<ol>
<li>Diluir 5 mL da solução UA de 0,4 mM com água de 5 mL em um frasco de vidro de 15 mL para dar 10 mL de solução UA de 0,2 mM. Aperte a tampa e sonicate por 30 s.</li>
		<li>Repita a etapa 3.3.1 usando uma quantidade apropriada de UA e água conforme descrito na Tabela 1.</li>
	</ol>
</li>
	<li>Preparação dos complexos CB7-UA<ol>
<li>Adicione 0,75 mL da solução CB7 de 0,4 mM e 0,75 mL de solução UA de 0,4 mM em um tubo de 1,5 mL. Fixar a tampa e sonicar por 30 s.</li>
		<li>Aguarde 30 min para garantir a formação de complexos hospedeiros-convidados.</li>
		<li>Repita o passo 3.4.1 – 3.4.2 usando a solução UA de diferentes concentrações.</li>
	</ol>
</li>
</ol>4. Sensoriamento sers de UA
<ol><li>Configuração experimental do sistema Raman (Figura 3)<ol>
<li>Ligue o laser He-Ne de 633 nm (22,5 mW).</li>
		<li>Ligue o espectrômetro modular Raman.</li>
		<li>Ligue o computador e inicie o software.</li>
		<li>Clique no ícone de assistente de aplicativo spectroscopia e selecione Raman.</li>
		<li>Comece uma nova aquisição. Defina o tempo de integração para 30 s, as varreduras para a média de 5 e o boxcar a 0.</li>
		<li>Armazene espectro de fundo e digite o comprimento de onda laser (ou seja, 633 nm). NOTA: O tempo de integração é o tempo para cada varredura, as varreduras a média é o número de varreduras médias para criar cada espectro e o boxcar é o número de pixels vizinhos em média28.</li>
	</ol>
</li>
	<li>Formação dos substratos sers<ol>
<li>Adicione 0,9 mL da solução Au NP de 40 nm e 0,1 mL da solução do complexo CB7-UA pré-formada em um tubo de 1,5 mL. Fixar a tampa e sonicar até que a solução mude de vermelho-rubi para roxo. NOTA: Também podem ser utilizadas amostras de solução Au NP estabilizadas por citrato comercial de 40 nm. Normalmente, a densidade óptica do pico de ressonância de plasmon de superfície localizada (LSPR) é ajustada para 1 através de diluição de amostras concentradas de solução de estoque. A concentração de citrato na amostra é tipicamente mantida como 2 mM.</li>
		<li>Transfira a solução amostral para um semi-micro cuvette. Coloque a cuvette no suporte de amostra Raman e feche a tampa.</li>
		<li>Comece a medição.</li>
		<li>Configure a economia automática para registrar cinco espectros sers consecutivos.</li>
		<li>Pare a medição e altere a amostra.</li>
		<li>Repita o passo 4.2.1 – 4.2.5 usando a solução CB7-UA de diferentes concentrações. NOTA: O tempo de agregação é considerado dependente da concentração de UA nos nanoagregados, variando de 30 s para 0,1 μM UA a 30 min para 20 μM UA, devido à diferença na concentração de CB7 vazio que tem grande contribuição para mediar a agregação de Au NPs. Para o complexo CB7-UA, um portal é bloqueado pela molécula UA volumosa, tornando-o indisponível para ligação à superfície Au NP e, portanto, incapaz de mediar a agregação NP21. A amostra está pronta para medição quando a cor da solução mudar de vermelho-rubi para roxo.</li>
	</ol>
</li>
</ol>5. Análise de dados
<ol><li>Processamento de dados<ol>
<li>Baixe e instale a linha de base com plugin assimétrico de quadrados mínimos (ALS) no Origin. NOTA: O plugin ALS requer OriginPro.</li>
		<li>Insira os dados brutos na Origem.</li>
		<li>Calcule um valor médio a partir dos cinco espectros SERS de cada amostra. Divida o valor pela potência do laser (ou seja, 22,5 mW) e pelo tempo de integração (ou seja, 30 s).</li>
		<li>Clique no ícone ALS para abrir a caixa de diálogo. Defina o fator assimétrico para 0,001, limiar para 0,03 %, fator de suavização para 2 e número de iterações para 20 para corrigir a linha de base de cada espectro médio.</li>
		<li>Plote o espectro SERS de diferentes concentrações de UA usando linhas empilhadas por y deslocamentos. A saída deve ser intensidade (conta s-1 mW-1) contra o câmbio Raman (cm-1).</li>
	</ol>
</li>
</ol>

<ol>
	<li>Villa, J. E. L., Poppi, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+portable+SERS+method+for+the+determination+of+uric+acid+using+a+paper-based+substrate+and+multivariate+curve+resolution.">A portable SERS method for the determination of uric acid using a paper-based substrate and multivariate curve resolution.</a> Analyst. 141 (6), 1966-1972 (2016).</li><li>Westley, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Absolute+Quantification+of+Uric+Acid+in+Human+Urine+Using+Surface+Enhanced+Raman+Scattering+with+the+Standard+Addition+Method.">Absolute Quantification of Uric Acid in Human Urine Using Surface Enhanced Raman Scattering with the Standard Addition Method.</a> Analytical Chemistry. 89 (4), 2472-2477 (2017).</li><li>Zhao, L., Blackburn, J., Brosseau, C. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+Detection+of+Uric+Acid+by+Electrochemical-Surface+Enhanced+Raman+Spectroscopy+Using+a+Multilayered+Au/Ag+Substrate.">Quantitative Detection of Uric Acid by Electrochemical-Surface Enhanced Raman Spectroscopy Using a Multilayered Au/Ag Substrate.</a> Analytical Chemistry. 87 (1), 441-447 (2015).</li><li>Goodall, B. L., Robinson, A. M., Brosseau, C. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrochemical-surface+enhanced+Raman+spectroscopy+(E-SERS)+of+uric+acid:+a+potential+rapid+diagnostic+method+for+early+preeclampsia+detection.">Electrochemical-surface enhanced Raman spectroscopy (E-SERS) of uric acid: a potential rapid diagnostic method for early preeclampsia detection.</a> Physical Chemistry Chemical Physics. 15 (5), 1382-1388 (2013).</li><li>Lytvyn, Y., Perkins, B. A., Cherney, D. Z. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Uric+Acid+as+a+Biomarker+and+a+Therapeutic+Target+in+Diabetes.">Uric Acid as a Biomarker and a Therapeutic Target in Diabetes.</a> Canadian Journal of Diabetes. 39 (3), 239-246 (2015).</li><li>Ali, S. M. U., Ibupoto, Z. H., Kashif, M., Hashim, U., Willander, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Potentiometric+Indirect+Uric+Acid+Sensor+Based+on+ZnO+Nanoflakes+and+Immobilized+Uricase.">A Potentiometric Indirect Uric Acid Sensor Based on ZnO Nanoflakes and Immobilized Uricase.</a> Sensors. 12 (3), 2787-2797 (2012).</li><li>Yu, J., Wang, S., Ge, L., Ge, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+chemiluminescence+paper+microfluidic+biosensor+based+on+enzymatic+reaction+for+uric+acid+determination.">A novel chemiluminescence paper microfluidic biosensor based on enzymatic reaction for uric acid determination.</a> Biosensors and Bioelectronics. 26 (7), 3284-3289 (2011).</li><li>Yang, Y. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+determination+of+creatine,+uric+acid,+creatinine+and+hippuric+acid+in+urine+by+high+performance+liquid+chromatography.">Simultaneous determination of creatine, uric acid, creatinine and hippuric acid in urine by high performance liquid chromatography.</a> Biomedical Chromatography. 12 (2), 47-49 (1999).</li><li>Zhao, S., Wang, J., Ye, F., Liu, Y. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+uric+acid+in+human+urine+and+serum+by+capillary+electrophoresis+with+chemiluminescence+detection.">Determination of uric acid in human urine and serum by capillary electrophoresis with chemiluminescence detection.</a> Analytical Biochemistry. 378 (2), 127-131 (2008).</li><li>Fang, Y., Seong, N. H., Dlott, D. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+the+Distribution+of+Site+Enhancements+in+Surface-Enhanced+Raman+Scattering.">Measurement of the Distribution of Site Enhancements in Surface-Enhanced Raman Scattering.</a> Science. 321 (5887), 388-392 (2008).</li><li>Jeong, H. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dispersion+and+shape+engineered+plasmonic+nanosensors.">Dispersion and shape engineered plasmonic nanosensors.</a> Nature Communications. 7, 11331 (2016).</li><li>Alula, M. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+of+silver+nanoparticles+coated+ZnO/Fe3O4+composites+using+chemical+reduction+method+for+sensitive+detection+of+uric+acid+via+surface-enhanced+Raman+spectroscopy.">Preparation of silver nanoparticles coated ZnO/Fe3O4 composites using chemical reduction method for sensitive detection of uric acid via surface-enhanced Raman spectroscopy.</a> Analytica Chimica Acta. 1073, 62-71 (2019).</li><li>Bast&#250;s, N. G., Comenge, J., Puntes, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetically+Controlled+Seeded+Growth+Synthesis+of+Citrate-Stabilized+Gold+Nanoparticles+of+up+to+200+nm:+Size+Focusing+versus+Ostwald+Ripening.">Kinetically Controlled Seeded Growth Synthesis of Citrate-Stabilized Gold Nanoparticles of up to 200 nm: Size Focusing versus Ostwald Ripening.</a> Langmuir. 27 (17), 11098-11105 (2011).</li><li>Jeong, H. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selectable+Nanopattern+Arrays+for+Nanolithographic+Imprint+and+Etch-Mask+Applications.">Selectable Nanopattern Arrays for Nanolithographic Imprint and Etch-Mask Applications.</a> Advanced Science. 2 (7), 1500016 (2016).</li><li>Loh, X. J., Lee, T. C., Dou, Q., Deen, G. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Utilising+inorganic+nanocarriers+for+gene+delivery.">Utilising inorganic nanocarriers for gene delivery.</a> Biomaterials Science. 4 (1), 70-86 (2016).</li><li>Celiz, A. D., Lee, T. C., Scherman, O. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymer-Mediated+Dispersion+of+Gold+Nanoparticles:+Using+Supramolecular+Moieties+on+the+Periphery.">Polymer-Mediated Dispersion of Gold Nanoparticles: Using Supramolecular Moieties on the Periphery.</a> Advanced Materials. 21 (38), 3937-3940 (2009).</li><li>Lee, T. C., Scherman, O. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Formation+of+Dynamic+Aggregates+in+Water+by+Cucurbit[5]uril+Capped+with+Gold+Nanoparticles.">Formation of Dynamic Aggregates in Water by Cucurbit[5]uril Capped with Gold Nanoparticles.</a> ChemComm. 46 (14), 2438-2440 (2010).</li><li>Lee, T. C., Scherman, O. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Facile+Synthesis+of+Dynamic+Supramolecular+Aggregates+of+Cucurbit[n]uril+(n+=+5-8)+Capped+with+Gold+Nanoparticles+in+Aqueous+Media.">A Facile Synthesis of Dynamic Supramolecular Aggregates of Cucurbit[n]uril (n = 5-8) Capped with Gold Nanoparticles in Aqueous Media.</a> Chemistry-A European Journal. 18 (6), 1628-1633 (2012).</li><li>Taylor, R. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Precise+Subnanometer+Plasmonic+Junctions+for+SERS+within+Gold+Nano-+particle+Assemblies+Using+Cucurbit[n]uril+"Glue".">Precise Subnanometer Plasmonic Junctions for SERS within Gold Nano- particle Assemblies Using Cucurbit[n]uril "Glue".</a> ACS Nano. 5 (5), 3878-3887 (2011).</li><li>Peveler, W. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cucurbituril-mediated+quantum+dot+aggregates+formed+by+aqueous+self-assembly+for+sensing+applications.">Cucurbituril-mediated quantum dot aggregates formed by aqueous self-assembly for sensing applications.</a> ChemComm. 55 (38), 5495-5498 (2019).</li><li>Chio, W. I. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selective+Detection+of+Nitroexplosives+Using+Molecular+Recognition+within+Self-Assembled+Plasmonic+Nanojunctions.">Selective Detection of Nitroexplosives Using Molecular Recognition within Self-Assembled Plasmonic Nanojunctions.</a> The Journal of Physical Chemistry C. 123 (25), 15769-15776 (2019).</li><li>Kasera, S., Biedermann, F., Baumberg, J. J., Scherman, O. A., Mahajan, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+SERS+Using+the+Sequestration+of+Small+Molecules+Inside+Precise+Plasmonic+Nanoconstructs.">Quantitative SERS Using the Sequestration of Small Molecules Inside Precise Plasmonic Nanoconstructs.</a> Nano Letters. 12 (11), 5924-5928 (2012).</li><li>Taylor, R. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+Situ+SERS+Monitoring+of+Photochemistry+within+a+Nanojunction+Reactor.">In Situ SERS Monitoring of Photochemistry within a Nanojunction Reactor.</a> Nano Letters. 13 (12), 5985-5990 (2013).</li><li>Kasera, S., Herrmann, L. O., Barrio, J. d., Baumberg, J. J., Scherman, O. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+Multiplexing+with+Nano-Self-Assemblies+in+SERS.">Quantitative Multiplexing with Nano-Self-Assemblies in SERS.</a> Scientific Reports. 4, 6785 (2014).</li><li>Chio, W. I. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dual-triggered+nanoaggregates+of+cucurbit[7]uril+and+gold+nanoparticles+for+multi-spectroscopic+quantification+of+creatinine+in+urinalysis.">Dual-triggered nanoaggregates of cucurbit[7]uril and gold nanoparticles for multi-spectroscopic quantification of creatinine in urinalysis.</a> Journal of Materials Chemistry C. 8, 7051-7058 (2020).</li><li>Turkevich, J., Stevenson, P. C., Hillier, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+study+of+the+nucleation+and+growth+processes+in+the+synthesis+of+colloidal+gold.">A study of the nucleation and growth processes in the synthesis of colloidal gold.</a> Discussions of the Faraday Society. 11, 55-75 (1951).</li><li>Lagona, J., Mukhopadhyay, P., Chakrabarti, S., Issacs, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+cucurbit[n]uril+family.">The cucurbit[n]uril family.</a> Angewandte Chemie International Edition. 44 (31), 4844-4870 (2005).</li><li>. OceanView Installation and Operation Manual Available from: <a target="_blank" href="https://www.oceaninsight.com/globalassets/catalog-blocks-and-images/manuals--instruction-old-logo/software/oceanviewio.pdf">https://www.oceaninsight.com/globalassets/catalog-blocks-and-images/manuals--instruction-old-logo/software/oceanviewio.pdf</a> (2013)</li><li>Mahajan, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Raman+and+SERS+spectroscopy+of+cucurbit[n]urils.">Raman and SERS spectroscopy of cucurbit[n]urils.</a> Physical Chemistry Chemical Physics. 12 (35), 10429-10433 (2010).</li><li>Langer, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Present+and+Future+of+Surface-Enhanced+Raman+Scattering.">Present and Future of Surface-Enhanced Raman Scattering.</a> ACS Nano. 14 (1), 28-117 (2020).</li><li>Pilot, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Review+on+Surface-Enhanced+Raman+Scattering.">A Review on Surface-Enhanced Raman Scattering.</a> Biosensors. 9 (2), 57 (2019).</li><li>Bantz, K. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+progress+in+SERS+biosensing.">Recent progress in SERS biosensing.</a> Physical Chemistry Chemical Physics. 13 (24), 11551-11567 (2011).</li><li>Moore, T. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+Vitro+and+In+Vivo+SERS+Biosensing+for+Disease+Diagnosis.">In Vitro and In Vivo SERS Biosensing for Disease Diagnosis.</a> Biosensors. 8 (2), 46 (2018).</li><li>Bonifacio, A., Cervo, S., Sergo, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Label-free+surface-enhanced+Raman+spectroscopy+of+biofluids:+fundamental+aspects+and+diagnostic+applications.">Label-free surface-enhanced Raman spectroscopy of biofluids: fundamental aspects and diagnostic applications.</a> Analytical and Bioanalytical Chemistry. 407 (27), 8265-8277 (2015).</li><li>Jeong, H. H., Choi, E., Ellis, E., Lee, T. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+advances+in+gold+nanoparticles+for+biomedical+applications:+from+hybrid+structures+to+multi-functionality.">Recent advances in gold nanoparticles for biomedical applications: from hybrid structures to multi-functionality.</a> Journal of Materials Chemistry B. 7 (22), 3480-3496 (2019).</li><li>Premasiri, W. R., Clarke, R. H., Womble, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Urine+Analysis+by+Laser+Raman+Spectroscopy.">Urine Analysis by Laser Raman Spectroscopy.</a> Lasers in Surgery and Medicine. 28 (4), 330-334 (2001).</li><li>Lu, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Superhydrophobic+silver+film+as+a+SERS+substrate+for+the+detection+of+uric+acid+and+creatinine.">Superhydrophobic silver film as a SERS substrate for the detection of uric acid and creatinine.</a> Biomedical Optics Express. 9 (10), 4988-4997 (2018).</li><li>Feig, D. I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serum+Uric+Acid:+A+Risk+Factor+and+a+Target+for+Treatment.">Serum Uric Acid: A Risk Factor and a Target for Treatment.</a> Journal of the American Society of Nephrology. 17 (4), 69-73 (2006).</li><li>Maiuolo, J., Oppedisano, F., Gratteri, S., Muscoli, C., Mollace, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+uric+acid+metabolism+and+excretion.">Regulation of uric acid metabolism and excretion.</a> International Journal of Cardiology. 213, 8-14 (2016).</li></ol>

Os autores não têm nada a revelar.

O método de síntese automatizada descrito no protocolo permite que os Au NPs de tamanhos crescentes sejam reproduzidos. Embora existam alguns elementos que ainda precisam ser realizados manualmente, como a rápida adição de citrato de sódio durante a síntese de sementes e a verificação periódica para garantir que a tubulação PEEK seja segura, este método permite NPs Au de grandes tamanhos (até 40 nm), o que normalmente exigiria múltiplas injeções manuais de HAuCl4 e citrato de sódio, para ser...

O ácido úrico, que é o produto final do metabolismo de nucleotídeos de purina, é um importante biomarcador no soro sanguíneo e na urina para o diagnóstico de doenças como gota, pré-eclâmpsia, doenças renais, hipertensão, doenças cardiovasculares e diabetes 1,2,3,4,5. Os métodos atuais para detecção de ácido úrico incluem ensaios enzimáticos colorimétricos, cromatografia líquida de alto desempenho e eletroforese capilar, que são demorados, caros e requerem uma preparação amostral sofisticada 6,7,8,9.
A espectroscopia raman aprimorada na superfície é uma técnica promissora para o diagnóstico rotineiro de ponto de cuidado, pois permite a detecção seletiva de biomoléculas através de suas impressões digitais de vibração e oferece inúmeras vantagens como alta sensibilidade, resposta rápida, facilidade de uso e sem preparação ou mínima de amostras. Substratos sers baseados em nanopartículas metálicas nobres (por exemplo, NPs Au) podem aumentar os sinais de Raman das moléculas de analito em 4 a 10 ordens de magnitude10 através de forte aprimoramento eletromagnético causado pela ressonância de plasmon de superfície11. Os Au NPs de tamanhos sob medida podem ser facilmente sintetizados em oposição à fabricação demorada de nanocompositos metálicos complexos12, e, portanto, são amplamente utilizados em aplicações biomédicas devido às suas propriedades superiores 13,14,15,16. Apego de moléculas macrocíclicas, cucurbit[n]urils (CBn, onde n = 5-8, 10), na superfície dos NPs Au podem melhorar ainda mais os sinais sers das moléculas de analito, pois as moléculas de CB altamente simétricas e rígidas podem controlar o espaçamento preciso entre os Au NPs e localizar as moléculas de analito no centro ou nas proximidades dos hotspots plasmônicos através da formação de complexos hospedeiros-convidados (Figura 1)17, 18,19,20. Exemplos anteriores de estudos do SERS utilizando Au NP: CBn nanoagreguras incluem nitroexplosivos, aromáticos policíclicos, diaminostilbena, neurotransmissores e creatinina 21,22,23,24,25, com as medidas sers sendo realizadas em uma cuvette ou carregando uma pequena gota em um portador de amostra personalizado. Este esquema de detecção é particularmente útil para quantificar rapidamente biomarcadores em uma matriz complexa com uma alta reprodutibilidade.
Aqui, um método fácil para formar complexos hospedeiros-convidados de CB7 e um importante biomarcador UA, e quantificar UA com um limite de detecção de 0,2 μM via agregações mediadas por CB7 de Au NPs em mídia aquosa foi demonstrado usando um espectrômetro modular, o que é promissor para aplicações diagnósticas e clínicas.

<table>
	<tbody>
		<tr>
			<td>40 nm gold nanoparticles</td>
			<td>NanoComposix</td>
			<td>AUCN40-100M</td>
			<td>NanoXact, 0.05 mg/ mL, bare (citrate)</td>
		</tr>
		<tr>
			<td>Centrifuge tube</td>
			<td>Corning Falcon</td>
			<td>14-432-22</td>
			<td>50 mL volume</td>
		</tr>
		<tr>
			<td>Cucurbit[7]uril</td>
			<td>Lab-made</td>
			<td></td>
			<td>see ref. 19</td>
		</tr>
		<tr>
			<td>Gold(III) chloride trihydrate</td>
			<td>Sigma aldrich</td>
			<td>520918</td>
			<td>&#8805;99.9% trace metals basis</td>
		</tr>
		<tr>
			<td>Luer lock disposable syringe</td>
			<td>Cole-Parmer</td>
			<td>WZ-07945-15</td>
			<td>3 mL volume</td>
		</tr>
		<tr>
			<td>Luer-to-MicroTight adapter</td>
			<td>LuerTight</td>
			<td>P-662</td>
			<td>360 &#956;m outer diameter Tubing to Luer Syringe</td>
		</tr>
		<tr>
			<td>PEEK tubing</td>
			<td>IDEX</td>
			<td>1572</td>
			<td>360 &#956;m outer diameter, 150 &#956;m inner diameter</td>
		</tr>
		<tr>
			<td>PEEK tubing cutter</td>
			<td>IDEX</td>
			<td>WZ-02013-30</td>
			<td>Capillary Polymer Chromatography Tubing Cutter For 360 &#181;m to 1/32&#34; OD tubing</td>
		</tr>
		<tr>
			<td>Raman spectrometer</td>
			<td>Ocean Optics</td>
			<td>QE pro</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium citrate tribasic dihydrate</td>
			<td>Sigma aldrich</td>
			<td>S4641</td>
			<td>ACS reagent, &#8805;99.0%</td>
		</tr>
		<tr>
			<td>Sonicator</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Standard Probe</td>
			<td>Digi-Sense</td>
			<td>WZ-08516-55</td>
			<td>Type-K</td>
		</tr>
		<tr>
			<td>Syringe pump</td>
			<td>Aladdin</td>
			<td>ALADDIN2-220</td>
			<td>2 syringes, maximum syringe volume 60 mL</td>
		</tr>
		<tr>
			<td>Thermocouple thermometer</td>
			<td>Digi-Sense</td>
			<td>WZ-20250-91</td>
			<td>Single-Input Thermocouple Thermometer with NIST-Traceable Calibration</td>
		</tr>
		<tr>
			<td>ThermoMixer</td>
			<td>Eppendorf</td>
			<td>5382000031</td>
			<td>With an Eppendorf SmartBlock for 50 mL tubes</td>
		</tr>
		<tr>
			<td>Uric acid</td>
			<td>Sigma aldrich</td>
			<td>U2625</td>
			<td>&#8805;99%, crystalline</td>
		</tr>
	</tbody>
</table>

quantitative sers detection of uric acid via formation of precise plasmonic nanojunctions within aggregates of gold nanoparticles and cucurbit[n]uril

Este trabalho descreve um método rápido e altamente sensível para a detecção quantitativa de um importante biomarcador, ácido úrico (UA), via espectrescopia raman aumentada pela superfície (SERS) com um baixo limite de detecção de ~0,2 μM para múltiplos picos característicos na região da impressão digital, usando um espectrômetro modular. Este esquema de biosensação é mediado pela complexidade hospedeira-hóspede entre um macrociclo, cucurbit[7]uril (CB7) e UA, e a subsequente formação de nanojunções plasmônicas precisas dentro do Au NP auto-montado: nanoaggregados CB7. Uma síntese fácil de Au NP de tamanhos desejáveis para substratos SERS também foi realizada com base na abordagem clássica de redução de citratos com uma opção a ser facilitada usando um sintetizador automatizado construído em laboratório. Este protocolo pode ser facilmente estendido à detecção multiplexada de biomarcadores em fluidos corporais para aplicações clínicas.

Na síntese de Au NP apresentada, os espectros UV-Vis mostram uma mudança dos picos de LSPR de 521 nm para 529 nm após 10 passos de crescimento (Figura 4A,B) enquanto os dados do DLS mostram uma distribuição de tamanho estreito à medida que o tamanho dos NPs Au aumenta de 25,9 nm para 42,8 nm (Figura 4C,D). Os tamanhos médios de G0, G5 e G10 medidos a partir de imagens TEM (Figura 4E) são de ...

Watch this Scientific Journal Video about Quantitative SERS Detection of Uric Acid via Formation of Precise Plasmonic Nanojunctions within Aggregates of Gold Nanoparticles and Cucurbit[n]uril at JoVE.

Quantitative SERS Detection of Uric Acid via Formation of Precise Plasmonic Nanojunctions within Aggregates of Gold Nanoparticles and Cucurbit[n]uril

Um complexo hospedeiro-convidado de cucurbit[7]uril e ácido úrico foi formado em uma solução aquosa antes de adicionar uma pequena quantidade em solução Au NP para a espectróscopia raman (SERS) com visão quantitativa de Raman (SERS) com um espectrômetro modular.

Detecção quantitativa de sers de ácido úrico através da formação de nanojunções plasmônicas precisas dentro de Agregados de Nanopartículas de Ouro e Cucurbit[n]uril

This work describes a rapid and highly sensitive method for the quantitative detection of an important biomarker, uric acid (UA), via surface-enhanced ...

quantitative-sers-detection-uric-acid-via-formation-precise-plasmonic

Research

JoVE Journal

Chemistry

Quantitative SERS Detection of Uric Acid via Formation of Precise Plasmonic Nanojunctions within Aggregates of Gold Nanoparticles and Cucurbit[n]uril

3.7K visualizações.  University College London (UCL). Um complexo hospedeiro-convidado de cucurbit[7]uril e ácido úrico foi formado em uma solução aquosa antes de adicionar uma pequena quantidade em solução Au NP para a espectróscopia raman (SERS) com visão quantitativa de Raman (SERS) com um espectrômetro modular.

Vídeo: Quantitative SERS Detection of Uric Acid via Formation of Precise Plasmonic Nanojunctions within Aggregates of Gold Nanoparticles and Cucurbit[n]uril

Template Directed Synthesis of Plasmonic Gold Nanotubes with Tunable IR Absorbance

A nearly parallel array of pores can be produced by anodizing aluminum foils in acidic environments1, 2. Applications of anodic aluminum oxide (AAO) membranes have been under development since the 1990's and have become a common method to template the synthesis of high aspect ratio nanostructures, mostly by electrochemical growth or pore-wetting. Recently, these membranes have become commercially available in a wide range of pore sizes and densities, leading to an extensive library of functional nanostructures being synthesized from AAO membranes. These include composite nanorods, nanowires and nanotubes made of metals, inorganic materials or polymers 3-10. Nanoporous membranes have been used to synthesize nanoparticle and nanotube arrays that perform well as refractive index sensors, plasmonic biosensors, or surface enhanced Raman spectroscopy (SERS) substrates 11-16, as well as a wide range of other fields such as photo-thermal heating 17, permselective transport 18, 19, catalysis 20, microfluidics 21, and electrochemical sensing 22, 23. Here, we report a novel procedure to prepare gold nanotubes in AAO membranes. Hollow nanostructures have potential application in plasmonic and SERS sensing, and we anticipate these gold nanotubes will allow for high sensitivity and strong plasmon signals, arising from decreased material dampening 15.

Solution-suspendable gold nanotubes with controlled dimensions can be synthesized by electrochemical deposition in porous anodic aluminum oxide (AAO) membranes using a hydrophobic polymer core. Gold nanotubes and nanotube arrays hold promise for applications in plasmonic biosensing, surface-enhanced Raman spectroscopy, photo-thermal heating, ionic and molecular transport, microfluidics, catalysis and electrochemical sensing.

Dirigido modelo de síntese de nanotubos de Ouro plasmônicos com Absorbância IR Tunable

A nearly parallel array of pores can be produced by anodizing aluminum foils in acidic environments1, 2. Applications of anodic aluminum oxide (AAO) ...

Química

Preparation of Silica Nanoparticles Through Microwave-assisted Acid-catalysis

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle diameters ranging from 30-250 nm by varying the reaction conditions. Through the selection of a microwave compatible solvent, silicic acid precursor, catalyst, and microwave irradiation time, these microwave-assisted methods were capable of overcoming the previously reported shortcomings associated with synthesis of silica nanoparticles using microwave reactors. The siloxane precursor was hydrolyzed using the acid catalyst, HCl. Acetone, a low-tan &#948; solvent, mediates the condensation reactions and has minimal interaction with the electromagnetic field. Condensation reactions begin when the silicic acid precursor couples with the microwave radiation, leading to silica nanoparticle sol formation. The silica nanoparticles were characterized by dynamic light scattering data and scanning electron microscopy, which show the materials&#39; morphology and size to be dependent on the reaction conditions. Microwave-assisted reactions produce silica nanoparticles with roughened textured surfaces that are atypical for silica sols produced by St&#246;ber&#39;s methods, which have smooth surfaces.

Silica nanoparticles were prepared using acid-catalysis of a siloxane precursor and microwave-assisted synthetic techniques resulting in the controlled growth of nanomaterials ranging from 30-250 nm in diameter. The growth dynamics can be controlled by varying the initial silicic acid concentration, time of the reaction, and temperature of reaction.

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle ...

A Simple Method for the Size Controlled Synthesis of Stable Oligomeric Clusters of Gold Nanoparticles under Ambient Conditions

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like oligomeric clusters of these yellow nanoparticles of narrow size distribution are synthesized under ambient conditions via two methods. The delay-time method controls the number of subunits in the oligoclusters by varying the time between the addition of HAuCl4 to alkaline solution and the subsequent addition of reducing agent, NaSCN. The yellow oligoclusters produced range in size from ~3 to ~25 nm. This size range can be further extended by an add-on method utilizing hydroxylated gold chloride (Na+[Au(OH4-x)Clx]-) to auto-catalytically increase the number of subunits in the as-synthesized oligocluster nanoparticles, providing a total range of 3 nm to 70 nm. The crude oligocluster preparations display narrow size distributions and do not require further fractionation for most purposes. The oligoclusters formed can be concentrated &#62;300 fold without aggregation and the crude reaction mixtures remain stable for weeks without further processing. Because these oligomeric clusters can be concentrated before derivatization they allow expensive derivatizing agents to be used economically. In addition, we present two models by which predictions of particle size can be made with great accuracy.

We describe a simple method for producing highly stable oligomeric clusters of gold nanoparticles via the reduction of chloroauric acid (HAuCl4) with sodium thiocyanate (NaSCN). The oligoclusters have a narrow size distribution and can be produced with a wide range of sizes and surface coats.

Um método simples para o tamanho Síntese controlada de estáveis ​​Oligoméricas Clusters de nanopartículas em condições ambientais

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like ...

Synthesis of Ligand-free CdS Nanoparticles within a Sulfur Copolymer Matrix

Aliphatic ligands are typically used during the synthesis of nanoparticles to help mediate their growth in addition to operating as high-temperature solvents. These coordinating ligands help solubilize and stabilize the nanoparticles while in solution, and can influence the resulting size and reactivity of the nanoparticles during their formation. Despite the ubiquity of using ligands during synthesis, the presence of aliphatic ligands on the nanoparticle surface can result in a number of problems during the end use of the nanoparticles, necessitating further ligand stripping or ligand exchange procedures. We have developed a way to synthesize cadmium sulfide (CdS) nanoparticles using a unique sulfur copolymer. This sulfur copolymer is primarily composed of elemental sulfur, which is a cheap and abundant material. The sulfur copolymer has the advantages of operating both as a high temperature solvent and as a sulfur source, which can react with a cadmium precursor during nanoparticle synthesis, resulting in the generation of ligand free CdS. During the reaction, only some of the copolymer is consumed to produce CdS, while the rest remains in the polymeric state, thereby producing a nanocomposite material. Once the reaction is finished, the copolymer stabilizes the nanoparticles within a solid polymeric matrix. The copolymer can then be removed before the nanoparticles are used, which produces nanoparticles that do not have organic coordinating ligands. This nascent synthesis technique presents a method to produce metal-sulfide nanoparticles for a wide variety of applications where the presence of organic ligands is not desired.

Herein we present a method to synthesize ligand-free cadmium sulfide (CdS) nanoparticles based on a unique sulfur copolymer. The sulfur copolymer operates as a high temperature solvent and a sulfur source during the nanoparticle synthesis and stabilizes the nanoparticles after the reaction.

Síntese de CDs Nanopartículas sem ligando dentro de uma matriz de copolímero de Enxofre

Aliphatic ligands are typically used during the synthesis of nanoparticles to help mediate their growth in addition to operating as high-temperature ...

An Optimized Protocol for the Efficient Radiolabeling of Gold Nanoparticles by Using a 125I-labeled Azide Prosthetic Group

Here, we demonstrate a detailed protocol for the radiosynthesis of a 125I-labeled azide prosthetic group and its application to the efficient radiolabeling of DBCO-group-functionalized gold nanoparticles using a copper-free click reaction. Radioiodination of the stannylated precursor (2) was carried out by using [125I]NaI and chloramine T as an oxidant at room temperature for 15 min. After HPLC purification of the crude product, the purified 125I-labeled azide (1) was obtained with high radiochemical yield (75 &plusmn; 10%, n = 8) and excellent radiochemical purity (&gt;99%). For the synthesis of radiolabeled 13-nm-sized gold nanoparticles, the DBCO-functionalized gold nanoparticles (3) were prepared by using a thiolated polyethylene glycol polymer. A copper-free click reaction between 1 and 3 gave the 125I-labeled gold nanoparticles (4) with more than 95% of radiochemical yield as determined by radio-thin-layer chromatography (radio-TLC). These results clearly indicate that the present radiolabeling method using a strain-promoted copper-free click reaction will be useful for the efficient and convenient radiolabeling of DBCO-group-containing nanomaterials.

An Optimized Protocol for the Efficient Radiolabeling of Gold Nanoparticles by Using a 125I-labeled Azide Prosthetic Group

A detailed procedure for the synthesis of a 125I-labeled azide and the radiolabeling of dibenzocyclooctyne (DBCO)-group-conjugated, 13-nm-sized gold nanoparticles using a copper-free click reaction is described.

Um protocolo otimizado para a radiomarcação eficiente de nanopartículas de ouro usando um<sup&gt; 125</sup&gt; Marcado com Eu Azida grupo prostético

Here, we demonstrate a detailed protocol for the radiosynthesis of a 125I-labeled azide prosthetic group and its application to the efficient ...

Luminophore Formation in Various Conformations of Bovine Serum Albumin by Binding of Gold(III)

The purpose of the presented protocols is to study the process of Au(III) binding to BSA, yielding conformation change-induced red fluorescence (&#955;em = 640 nm) of BSA-Au(III) complexes. The method adjusts the pH to show that the emergence of the red fluorescence is correlated with the pH-induced equilibrium transitions of the BSA conformations. Red fluorescent BSA-Au(III) complexes can only be formed with an adjustment of pH at or above 9.7, which corresponds to the &#34;A-form&#34; conformation of BSA. The protocol to adjust the BSA to Au molar ratio and to monitor the time-course of the process of Au(III) binding is described. The minimum number of Au(III) per BSA, to produce the red fluorescence, is less than seven. We describe the protocol in steps to illustrate the presence of multiple Au(III) binding sites in BSA. First, by adding copper (Cu(II)) or nickel (Ni(II)) cations followed by Au(III), this method reveals a binding site for Au(III) that is not the red fluorophore. Second, by modifying BSA by thiol capping agents, another nonfluorophore-forming Au(III) binding site is revealed. Third, changing the BSA conformation by cleaving and capping of the disulfide bonds, the possible Au(III) binding site(s) are illustrated. The protocol described, to control the BSA conformations and Au(III) binding, can be generally applied to study the interactions of other proteins and metal cations.

Luminophore Formation in Various Conformations of Bovine Serum Albumin by Binding of GoldIII

The protocols for studying the binding of gold cations (Au(III)) to various conformations of bovine serum albumin (BSA) as well as for characterizing the conformational dependent unique BSA-Au fluorescence are presented.

Lumíforo formação em várias conformações de albumina de soro bovino por ligação de Gold(III)

The purpose of the presented protocols is to study the process of Au(III) binding to BSA, yielding conformation change-induced red fluorescence (&#955;em ...

Synthesis and Characterization of Amphiphilic Gold Nanoparticles

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of their interactions with cell membranes, lipid bilayers, and viruses. The hydrophilic ligands make these particles colloidally stable in aqueous solutions and the combination with hydrophobic ligands creates an amphiphilic particle that can be loaded with hydrophobic drugs, fuse with the lipid membranes, and resist nonspecific protein adsorption. Many of these properties depend on nanoparticle size and the composition of the ligand shell. It is, therefore, crucial to have a reproducible synthetic method and reliable characterization techniques that allow the determination of nanoparticle properties and the ligand shell composition. Here, a one-phase chemical reduction, followed by a thorough purification to synthesize these nanoparticles with diameters below 5 nm, is presented. The ratio between the two ligands on the surface of the nanoparticle can be tuned through their stoichiometric ratio used during synthesis. We demonstrate how various routine techniques, such as transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), and ultraviolet-visible (UV-Vis) spectrometry, are combined to comprehensively characterize the physicochemical parameters of the nanoparticles.

Amphiphilic gold nanoparticles can be used in many biological applications. A protocol to synthesize gold nanoparticles coated by a binary mixture of ligands and a detailed characterization of these particles is presented.

Síntese e caracterização de nanopartículas de ouro Anfífilos

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of ...

Assembly of Gold Nanorods into Chiral Plasmonic Metamolecules Using DNA Origami Templates

The inherent addressability of DNA origami structures makes them ideal templates for the arrangement of metal nanoparticles into complex plasmonic nanostructures. The high spatial precision of a DNA origami-templated assembly allows controlling the coupling between plasmonic resonances of individual particles and enables tailoring optical properties of the constructed nanostructures. Recently, chiral plasmonic systems attracted a lot of attention due to the strong correlation between the spatial configuration of plasmonic assemblies and their optical responses (e.g., circular dichroism [CD]). In this protocol, we describe the whole workflow for the generation of DNA origami-based chiral assemblies of gold nanorods (AuNRs). The protocol includes a detailed description of the design principles and experimental procedures for the fabrication of DNA origami templates, the synthesis of AuNRs, and the assembly of origami-AuNR structures. In addition, the characterization of structures using transmission electron microscopy (TEM) and CD spectroscopy is included. The described protocol is not limited to chiral configurations and can be adapted for the construction of various plasmonic architectures.

We describe the detailed protocol for the DNA origami-based assembly of gold nanorods into chiral plasmonic metamolecules with strong chiroptical responses. The protocol is not limited to chiral configurations and can be easily adapted for the fabrication of various plasmonic architectures.

Montagem de Nanobastões de Ouro em Metamoléculas Plasmônicas Quirais Usando Modelos de Origami de DNA

The inherent addressability of DNA origami structures makes them ideal templates for the arrangement of metal nanoparticles into complex plasmonic ...

Performing Spectroscopy on Plasmonic Nanoparticles with Transmission-Based Nomarski-Type Differential Interference Contrast Microscopy

Differential interference contrast (DIC) microscopy is a powerful imaging tool that is most commonly employed for imaging microscale objects using visible-range light. The purpose of this protocol is to detail a proven method for preparing plasmonic nanoparticle samples and performing single particle spectroscopy on them with DIC microscopy. Several important steps must be followed carefully in order to perform repeatable spectroscopy experiments. First, landmarks can be etched into the sample substrate, which aids in locating the sample surface and in tracking the region of interest during experiments. Next, the substrate must be properly cleaned of debris and contaminants that can otherwise hinder or obscure examination of the sample. Once a sample is properly prepared, the optical path of the microscope must be aligned, using Kohler Illumination. With a standard Nomarski style DIC microscope, rotation of the sample may be necessary, particularly when the plasmonic nanoparticles exhibit orientation-dependent optical properties. Because DIC microscopy has two inherent orthogonal polarization fields, the wavelength-dependent DIC contrast pattern reveals the orientation of rod-shaped plasmonic nanoparticles. Finally, data acquisition and data analyses must be carefully performed. It is common to represent DIC-based spectroscopy data as a contrast value, but it is also possible to present it as intensity data. In this demonstration of DIC for single particle spectroscopy, the focus is on spherical and rod-shaped gold nanoparticles.

The goal of this protocol is to detail a proven approach for the preparation of plasmonic nanoparticle samples and for performing single particle spectroscopy on them with differential interference contrast (DIC) microscopy.

Realização de espectroscopia em nanopartículas Plasmonicas com microscopia de contraste de interferência diferencial de tipo Nomarski baseado em transmissão

Differential interference contrast (DIC) microscopy is a powerful imaging tool that is most commonly employed for imaging microscale objects using ...

Synthesis of Aptamer-PEI-g-PEG Modified Gold Nanoparticles Loaded with Doxorubicin for Targeted Drug Delivery

Due to drug resistance and toxicity in healthy cells, use of doxorubicin (DOX) has been limited in clinical cancer therapy. This protocol describes the designing of poly(ethylenimine) grafted with polyethylene glycol (PEI-g-PEG) copolymer functionalized gold nanoparticles (AuNPs) with loaded aptamer (AS1411) and DOX through amide reactions. AS1411 is specifically bonded with targeted nucleolin receptors on cancer cells so that DOX targets cancer cells instead of healthy cells. First, PEG is carboxylated, then grafted to branched PEI to obtain a PEI-g-PEG copolymer, which is confirmed by 1H NMR analysis. Next, PEI-g-PEG copolymer coated gold nanoparticles (PEI-g-PEG@AuNPs) are synthesized, and DOX and AS1411 are covalently bonded to AuNPs gradually via amide reactions. The diameter of the prepared AS1411-g-DOX-g-PEI-g-PEG@AuNPs is ~39.9 nm, with a zeta potential of -29.3 mV, indicating that the nanoparticles are stable in water and cell medium. Cell cytotoxicity assays show that the newly designed DOX loaded AuNPs are able to kill cancer cells (A549). This synthesis demonstrates the delicate arrangement of PEI-g-PEG copolymers, aptamers, and DOX on AuNPs that are achieved by sequential amide reactions. Such aptamer-PEI-g-PEG functionalized AuNPs provide a promising platform for targeted drug delivery in cancer therapy.

In this protocol, doxorubicin-loaded AS1411-g-PEI-g-PEG modified gold nanoparticles are synthesized via three-step amide reactions. Then, doxorubicin is loaded and delivered to target cancer cells for cancer therapy.

Síntese de Nanopartículas de ouro modificada Aptamer-PEI-g-PEG carregadas com doxorubicina para entrega de drogas direcionadas

Due to drug resistance and toxicity in healthy cells, use of doxorubicin (DOX) has been limited in clinical cancer therapy. This protocol describes the ...