KG è stato sostenuto dalla concessione P-1760 RA Welch Foundation, TCU Andrews Istituto di Matematica e Scienze della formazione (per KG), TCU ricerca e creatività Activity Grant (al KG) e TCU SERC Grant (a JHS).

1. Sintesi di biotina-Fc-cisteina (1) <ol><li> Metodi in fase solida per la produzione di resina-legato 1. <ol><li> Inserire biotina resina caricata (250 mg, 0,145 mmol) in una siringa sinterizzato e gonfiare la resina elaborando dimetilformammide (5 ml) e agitando la siringa su un agitatore di laboratorio per 20 min. Espellere la soluzione e ripetere dimetilformammide gonfiore ancora una volta. </li><li> Rimuovere il gruppo protettore Fmoc aggiungendo 4-6 ml di 20% piperidina in dimetilformammide alla siringa seguita da 10-15 minuti di agitazione. Ripetere il processo deprotezione con un altro 4-6 ml di piperidina. Lavare la resina con una sequenza di 3x dimetilformammide, 3x dimetilformammide: metanolo (1: 1), metanolo 3x: diclorometano (1: 1), 3x diclorometano, ~ 5 ml. Fare un test alla ninidrina (+) su un piccolo campione (~ 10) delle perle di confermare deprotezione successo dalla presenza di blu dopo riscaldamento. </li><li> Mescolare una soluzione contenente acido 1&#39;-Fmoc-ammino-ferrocene-1-carbossilico(203,3 mg, 0,4350 mmoli), 1-idrossibenzotriazolo idrato (58,8 mg, 0,413 mmoli), diisopropil carbodiimide (0,0673 ml, 0,435 mmoli), diisopropil etil ammina (0,0757 ml, 0,435 mmoli), e una miscela 4: 1 di diclorometano e dimetilformammide. Disegna questo nella siringa sinterizzato e scuotere delicatamente su un agitatore di laboratorio per 6 ore. Poi espellere la soluzione dalla siringa e lavare come descritto in precedenza. </li><li> Eseguire il test alla ninidrina (-) come descritto sopra per confermare accoppiamento. Il test ninidrina può ancora essere utile nel confermare accoppiamento nonostante il colore arancio del tallone derivato dal fissaggio del ferro contenente frazione. </li><li> Quindi rimuovere il gruppo Fmoc mediante l&#39;aggiunta di 20% piperidina in dimetilformammide e lavati come descritto sopra. Il test ninidrina (+) deve essere utilizzato per confermare la rimozione Fmoc. </li><li> Preparare una soluzione composta di Fmoc-Cys (Trt) -OH (254,8 mg, 0,4350 mmol), 1-idrossibenzotriazolo idrato (58,8 mg, 0,4125 mmol), diisopropil carbodiimide (0,0673 ml, 0,4350mmol), diisopropil etil ammina (0,0757 ml, 0,4350 mmoli), e una miscela 4: 1 di diclorometano e dimetilformammide. Aggiungi questo cocktail accoppiamento cisteina siringa sinterizzato e scuotere delicatamente per 6 ore. Lavare utilizzando il protocollo descritto in precedenza. </li><li> Conferma accoppiamento utilizzando il test alla ninidrina (-), seguita dalla rimozione del componente Fmoc con il 20% di piperidina e lavaggio. Verifica terminale libero ammina utilizzando il test alla ninidrina (+). </li></ol></li><li> Cleavage di 1 dalla resina. <ol><li> Fare una soluzione di TFA (9.45 ml), acqua (0,25 ml), 1,2-etanditiolo (0,25 ml), e triisopropyl silano (0,1 ml), aggiungere alla siringa e agitare delicatamente per 4 ore. </li><li> Raccogliere la risultante soluzione rosso-marrone in un tubo Eppendorf e si evapora il TFA lentamente utilizzando una corrente d&#39;aria. </li><li> Aggiungere fredda etere dietilico (~ 15 ml) al tubo Eppendorf precipitare 1, che costituirà agitazione. Isolare il prodotto tramite centrifugazione (1 g, 5 min). Tcicli gallina ripetute di lavaggi etere etilico (~ 60 ml totale) e centrifugare per ottenere 1 come rosso / marrone solido. </li></ol></li></ol> 2. Caratterizzazione e analisi di 1 <ol><li> Verificare che l&#39;identità corrisponde la connettività e la composizione mostrata in figura 2 con 1 H (16 scansioni) e 13 C NMR (512 scansioni) in metanolo deuterato (300 microlitri) e analisi ESI-MS. Aspettatevi i seguenti risultati: Spettro 1 H NMR (CD 3 OD) δ / ppm: 1,407-1,684 (m, 6H), 2.245 (t, 2H), 2,665-3,150 (m, 12H), 4,015 (t, 1H), 4.104 (d, 2H ), 4.274 (q, 1H), 4.426 (d, 2H), 4.479 (q, 1H), 4.595 (t, 1H) e 13 C NMR spettro (CD 3 OD) δ / ppm: 24,644 (CH 2), 25,472 (CH 2), 28,051 (CH 2), 28.300 (CH 2), 35,474 (CH 2), 38.698 (CH 2), 39,241 (CH 2), 39,717 (CH 2), 55,340 / 55,538 (Cp-ring), 60,286 (CH), 61,964 (CH), 62,521 / 62,821 (Cp-ring), 66,038 / 66,170 (Cp-ring), 69,153 / 69,328 (Cp-ring), 71,468 / 71,593 (Cp-ring), 76,466 (CH), 171,770 (C = O), 175,361 (C = O). ESI-MS (m / z): Trovato: 639.00 [1 + Na] +, teorica: 639,1 [1 + Na] + e HR-MS (m / z): Trovato: 617,2049 [1 + H] +, teorica: 617.1622 [1 + H] +. </li><li> Eseguire HPLC, analisi elementale conferma la composizione isolata 1. Eseguire i cromatogrammi HPLC utilizzando una colonna a fase inversa C8 100% MeOH ad una velocità di flusso di 0,5 ml / min. Nota: i tempi di ritenzione HPLC sono stati: 3,198-4,674 min. </li></ol> 3. L&#39;immobilizzazione di 1 su una superficie d&#39;oro <ol><li> Cut polimero sostenuto scivoli d&#39;oro in quadrati di ~ 0,25 in 2. </li><li> Riempire un bicchiere da 50 ml con una soluzione di acqua deionizzata di 1 (~ 1 mM). </li><li> Aggiungere la diapositiva oro al bicchiere e coprire con un vetro da orologio. Tuttoow il vetrino di incubare O / N a RT senza agitazione. </li><li> Rimuovere il vetrino oro dalla soluzione e lasciare asciugare all&#39;aria. </li><li> Ottenere la scansione di immagini di microscopia elettronica usando un microscopio elettronico a scansione (o equivalente) per osservare immobilizzato 1. </li></ol>

The authors have nothing to disclose.

La sintesi di derivati ​​asimmetrici ferrocene è impegnativo in soluzione. Ad esempio, i tentativi di produrre 1 in soluzione comportato basse rese di prodotto desiderato (meno del 20%). Analogamente, utilizzando reazioni 1&#39;-ammino-ferrocene acido carbossilico (sans Fmoc) e resina biotina legata determinato prodotto insolubile coerente con il prodotto polimerizzato riportato da Baristic et al. e prodotto minima. 47 Questo è ulteriormente complicato dal ferrocene e ...

I biosensori sono piccoli dispositivi che utilizzano la tecnologia di riconoscimento biomolecolare come piattaforma per l&#39;analisi selettiva e vengono utilizzati per la loro specificità, velocità e basso costo. Biosensori elettrochimici per la rilevazione di biomolecole sono all&#39;avanguardia di questo campo per la loro semplicità, economicità, ed alta sensibilità. 1,3 L&#39;anatomia generale di tali sensori è un elettrodo dotato di una molecola di riconoscimento specifico per il marcatore biologica di interesse . Il legame del biomarker dalla molecola di riconoscimento si traduce in una variazione locale del potenziale o corrente che può essere rilevato mediante misurazione semplice. Ad oggi la frazione riconoscimento può variare da enzimi, anticorpi 4-8, 9-12 cellule intere, recettori 13-16, 17-20 peptidi 21-23 e DNA 24 e sono in gran parte incentrati su grandi, molecole biologiche. 25-28 Research sforzi in questo campo si sono concentrati principalmente sulla immunosensori WHEre una immunoglobulina è immobilizzato con un nucleo attivo redox (come ferrocene) e utilizzato per rilevare un anticorpo di interesse. Questi studi sono stati esclusi dalle applicazioni cliniche a causa di una scarsa precisione e consumo di tempo derivanti dalle complicazioni derivanti dall&#39;uso di antigene / anticorpi. 1,3 crescente attenzione si è concentrata sulla rilevazione di piccole molecole (meno di 1 kg / mol) di biomedica , cibo e interesse ambientale, oltre alla sicurezza nazionale. 29 Gli esempi più noti di dispositivi di biosensori sono monitor glucosio auto-test, che hanno serigrafate elettrodi enzimi accoppiati ad un formato tascabile metri amperometrico. Questi sistemi tipicamente utilizzano un metodo coulometrico cui la quantità totale di carica generata dalla reazione di ossidazione del glucosio è misurata su un periodo di tempo. Dispositivi negoziabili devono essere portatile, robusto e tenuto in mano per fare uso facile per la popolazione in generale. Tags Redox quali ferrocene sono necessary di fornire il rilevamento elettrochimico di biomarcatori o piccole molecole in soluzione, come la maggior parte dei biomarcatori non sono intrinsecamente elettrochimicamente attivi. 30-38 Ferrocene è una molecola organometallica che è un gold standard per l&#39;elettrochimica, che lo rende una scelta eccellente per l&#39;integrazione in biosensori elettrochimici. Redox basata ferrocene-specie attive hanno già raccolto una notevole attenzione a causa delle loro piccole dimensioni, buona stabilità, l&#39;accesso sintetico comodo, facile modificazione chimica, relativa lipofilia, e la facilità di messa a punto redox. 3,30-42 Piccole molecole basate sul core ferrocene hanno stati ampiamente utilizzati come rivelatori di ioni metallici e piccole molecole. 32-38,43 sistemi di targeting specie più grandi come biomolecole hanno utilizzato l&#39;allegato di grandi anticorpi o immunoglobuline di derivati ​​del ferrocene che sono stati integrati su una superficie elettrochimica. 1,3,39 , 44 In ogni caso, il potenziale di intensi e correntety della coppia redox Fe III / Fe II è stato modificato su accoppiamento molecolare, producendo così una nuova maniglia spettroscopica che indica la presenza della molecola analita. Tale variazione è determinata dalla vasta sovrapposizione che si verifica tra il pi-sistema degli anelli ciclopentadienilici ed il ferro orbitali-d. Se il pi-sistema viene modificato, cioè, derivatizzato o reagito, allora l&#39;interazione orbitale, a sua volta, il cambiamento. Questo influenzerà il nucleo Fe e può essere osservata come un cambiamento nel potenziale della coppia Fe III / Fe II. 40,45,46 Queste proprietà rendono tale sistema attraente per l&#39;uso come agente quantificare in un immunodosaggio elettrochimica o biosensore. Per produrre sistemi ferrocene contenente specifici per portate biosensore è ottimale modificare un anello Cp con il bio-recettore specifico per una molecola bersaglio e utilizzare l&#39;altro anello Cp come tether molecolare per la lettura elettrochimica o elettrode (Figura 1). Sintesi di questi derivati ​​asimmetrici ferrocene è sfidato da reazioni laterali e la formazione di specie dimerica e polimeriche formate su intermolecular cross-linking. 47 Tuttavia, giunto chimica producendo un legame ammidico è la via più diretta per fornire semplici derivati ​​del ferrocene che coinvolgono componenti biologiche tali come peptidi e loro metaboliti. Pertanto, le tecniche in fase solida prima sviluppate nel 1950 da Merrifield per sintesi peptidica possono essere applicati a composti organometallici contenenti ferrocene. Attraverso l&#39;uso del ortogonalmente sostituito molecola di acido 1&#39;-Fmoc-ammino-ferrocene-1-carbossilico, un sistema ferrocene che può contenere una molecola recettore (biotina), lettura elettrochimica (ferrocene), e componente immobilizzare-linker (cisteina) presenta stato costruito e qui descritto. La sintesi di questo bio-coniugato è discusso così come prova per l&#39;immobilizzazione su una superficie d&#39;oro. Questo rappre lavorots la prima presentazione di un sistema composto da biotina, ferrocene ed un amminoacido per l&#39;immobilizzazione su una superficie d&#39;oro.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Biotin Novatag Resin</td>
			<td>NovaBiochem</td>
			<td>8550510001</td>
			<td></td>
		</tr>
		<tr>
			<td>TORVIQ 10ML LUER LOCK FRITTED SYRINGE</td>
			<td>Fisher</td>
			<td>NC9299151</td>
			<td></td>
		</tr>
		<tr>
			<td>piperdine</td>
			<td>Acros</td>
			<td>P/3520/PB05</td>
			<td></td>
		</tr>
		<tr>
			<td>ninhydrin test</td>
			<td>Sigma-Aldrich</td>
			<td>60017-1ea</td>
			<td></td>
		</tr>
		<tr>
			<td>1&#8217;-Fmoc-amino-ferrocene-1-carboxylic acid</td>
			<td>Omm Scientific</td>
			<td>Special Order</td>
			<td></td>
		</tr>
		<tr>
			<td>1-&#8203;Hydroxybenzotriazole hydrate</td>
			<td>Sigma-Aldrich</td>
			<td>157260-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N&#8242;-Diisopropylcarbodiimide</td>
			<td>Sigma-Aldrich</td>
			<td>D125407-5G</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N-&#8203;Diisopropylethylamine</td>
			<td>Sigma-Aldrich</td>
			<td>496219-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Fmoc-Cys(Trt)-OH</td>
			<td>Novabiochem</td>
			<td>8520080025</td>
			<td></td>
		</tr>
		<tr>
			<td>trifluoroacetic acid</td>
			<td>Sigma-Aldrich</td>
			<td>T5408</td>
			<td></td>
		</tr>
		<tr>
			<td>1,2-ethanedithiol</td>
			<td>Sigma-Aldrich</td>
			<td>2930</td>
			<td></td>
		</tr>
		<tr>
			<td>triisopropyl silane</td>
			<td>Sigma-Aldrich</td>
			<td>233781</td>
			<td></td>
		</tr>
		<tr>
			<td>Eppendorf tubes (20 mL)</td>
			<td>any source</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>methanol</td>
			<td>any source</td>
			<td></td>
			<td>dry with molecular sieves prior to use &#38; store in 100 mL media bottle for easy usage.</td>
		</tr>
		<tr>
			<td>dichloromethane</td>
			<td>any source</td>
			<td></td>
			<td>dry with molecular sieves prior to use &#38; store in 100 mL media bottle for easy usage.</td>
		</tr>
		<tr>
			<td>dimethylformamide</td>
			<td>any source</td>
			<td></td>
			<td>dry with molecular sieves prior to use &#38; store in 100 mL media bottle for easy usage.</td>
		</tr>
		<tr>
			<td>centrifuge</td>
			<td>any source</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

synthetic methodology for asymmetric ferrocene derived bio-conjugate systems via solid phase resin-based methodology

La diagnosi precoce è la chiave per il successo del trattamento della maggior parte delle malattie, ed è particolarmente importante per la diagnosi e il trattamento di molti tipi di cancro. Le tecniche più comuni utilizzate sono Imaging modalità, come la risonanza magnetica (MRI), tomografia ad emissione di Topografia (PET), e computerizzata Topografia (CT) e sono ottimali per la comprensione della struttura fisica della malattia, ma possono essere eseguite solo una volta ogni quattro sei settimane a causa dell&#39;uso di agenti di imaging e costo complessivo. Con questo in mente, lo sviluppo di &quot;point of care&quot; tecniche, come biosensori, che valutano lo stadio della malattia e / o l&#39;efficacia del trattamento in studio del medico e lo fanno in modo tempestivo, avrebbe rivoluzionato protocolli di trattamento. 1 come un mezzo per esplorare biosensori ferrocene base per la rilevazione di molecole biologicamente rilevanti 2, sono stati sviluppati metodi per produrre bio-coniugati ferrocene-biotina qui descritti. Questa relazione si concentrerà su un sistema biotina-ferrocene-cisteina che può essere immobilizzato su una superficie d&#39;oro.

La forma legata resina 1 è indicata in figura 2. L&#39;attacco covalente del componente ferrocene dà luogo ad una tinta arancione alle perle di resina che è persistente con lavaggio in continuo e indicativa di un ferro immobilizzato contenente complessa rispetto a assorbimento di ferro dal componente PEG del tallone resina. La forma priva di resina 1 è identico a colori per le perle di resina. Dopo la rimozione del composto dalla resina perline, la purezza e resa (6...

Watch this Scientific Journal Video about Synthetic Methodology for Asymmetric Ferrocene Derived Bio-conjugate Systems via Solid Phase Resin-based Methodology at JoVE.com

Synthetic Methodology for Asymmetric Ferrocene Derived Bio-conjugate Systems via Solid Phase Resin-based Methodology

The synthesis of asymmetric species of ferrocene is challenging using solution techniques. This report focuses on the methods carried out to produce a ferrocene-biotin bioconjugate using facile and clean reactions accomplished via solid-phase synthesis. Incorporation of a thiolate moiety is shown to impart the ability for immobilization on gold surfaces.

Metodologia sintetico per Asymmetric Ferrocene derivati ​​sistemi bio-coniugati attraverso Solid Metodologia Resina a base di fase

Early detection is a key to successful treatment of most diseases, and is particularly imperative for the diagnosis and treatment of many types of cancer. ...

synthetic-methodology-for-asymmetric-ferrocene-derived-bio-conjugate

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JoVE Journal

Chemistry

9.6K Views.  Texas Christian University. The synthesis of asymmetric species of ferrocene is challenging using solution techniques. This report focuses on the methods carried out to produce a ferrocene-biotin bioconjugate using facile and clean reactions accomplished via solid-phase synthesis. Incorporation of a thiolate moiety is shown to impart the ability for immobilization on gold surfaces.

Video: Synthetic Methodology for Asymmetric Ferrocene Derived Bio-conjugate Systems via Solid Phase Resin-based Methodology

High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems

The high pressure sapphire cell apparatus was constructed to visually determine the composition of multiphase systems without physical sampling. Specifically, the sapphire cell enables visual data collection from multiple loadings to solve a set of material balances to precisely determine phase composition. Ternary phase diagrams can then be established to determine the proportion of each component in each phase at a given condition. In principle, any ternary system can be studied although ternary systems (gas-liquid-liquid) are the specific examples discussed herein. For instance, the ternary THF-Water-CO2 system was studied at 25 and 40&#160;&#176;C and is described herein. Of key importance, this technique does not require sampling. Circumventing the possible disturbance of the system equilibrium upon sampling, inherent measurement errors, and technical difficulties of physically sampling under pressure is a significant benefit of this technique. Perhaps as important, the sapphire cell also enables the direct visual observation of the phase behavior. In fact, as the CO2 pressure is increased, the homogeneous THF-Water solution phase splits at about 2 MPa. With this technique, it was possible to easily and clearly observe the cloud point and determine the composition of the newly formed phases as a function of pressure.
The data acquired with the sapphire cell technique can be used for many applications. In our case, we measured swelling and composition for tunable solvents, like gas-expanded liquids, gas-expanded ionic liquids and Organic Aqueous Tunable Systems (OATS)1-4. For the latest system, OATS, the high-pressure sapphire cell enabled the study of (1) phase behavior as a function of pressure and temperature, (2) composition of each phase (gas-liquid-liquid) as a function of pressure and temperature and (3) catalyst partitioning in the two liquid phases as a function of pressure and composition. Finally, the sapphire cell is an especially effective tool to gather accurate and reproducible measurements in a timely fashion.

High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems

The high pressure sapphire cell apparatus is a unique tool to study, without sampling, phase behavior under a wide range of pressures. Using a cathetometer, very precise volume measurements can be recorded to measure liquid expansion and phase composition. Thus, this synthetic method enables the study of (1) phase equilibria of multi-component mixtures and (2) the partition behavior of catalyst or model compounds as a function of pressure.

Ad alta pressione Sapphire cellulare per la fase Equilibri misurazioni di CO<sub&gt; 2</sub&gt; / biologici / Water Systems

The high pressure sapphire cell apparatus was constructed to visually determine the composition of multiphase systems without physical sampling. ...

Ricerca

Chimica

Stabilizing Hepatocellular Phenotype Using Optimized Synthetic Surfaces

Currently, one of the major limitations in cell biology is maintaining differentiated cell phenotype. Biological matrices are commonly used for culturing and maintaining primary and pluripotent stem cell derived hepatocytes. While biological matrices are useful, they permit short term culture of hepatocytes, limiting their widespread application. We have attempted to overcome the limitations using a synthetic polymer coating. Polymers represent one of the broadest classes of biomaterials and possess a wide range of mechanical, physical and chemical properties, which can be fine-tuned for purpose. Importantly, such materials can be scaled to quality assured standards and display batch-to-batch consistency. This is essential if cells are to be expanded for high through-put screening in the pharmaceutical testing industry or for cellular based therapy. Polyurethanes (PUs) are one group of materials that have shown promise in cell culture. Our recent progress in optimizing a polyurethane coated surface, for long-term culture of human hepatocytes displaying stable phenotype, is presented and discussed.

This article will focus on developing polymer coated surfaces for long-term, stable culture of stem cell derived human hepatocytes.

Stabilizzazione epatocellulare Fenotipo Utilizzando superfici sintetiche ottimizzati

Currently, one of the major limitations in cell biology is maintaining differentiated cell phenotype. Biological matrices are commonly used for culturing ...

X-ray Powder Diffraction in Conservation Science: Towards Routine Crystal Structure Determination of Corrosion Products on Heritage Art Objects

The crystal structure determination and refinement process of corrosion products on historic art objects using laboratory high-resolution X-ray powder diffraction (XRPD) is presented in detail via two case studies.
The first material under investigation was sodium copper formate hydroxide oxide hydrate, Cu4Na4O(HCOO)8(OH)2&#8729;4H2O (sample 1) which forms on soda glass/copper alloy composite historic objects (e.g., enamels) in museum collections, exposed to formaldehyde and formic acid emitted from wooden storage cabinets, adhesives, etc. This degradation phenomenon has recently been characterized as &#34;glass induced metal corrosion&#34;.
For the second case study, thecotrichite, Ca3(CH3COO)3Cl(NO3)2&#8729;6H2O (sample 2), was chosen, which is an efflorescent salt forming needlelike crystallites on tiles and limestone objects which are stored in wooden cabinets and display cases. In this case, the wood acts as source for acetic acid which reacts with soluble chloride and nitrate salts from the artifact or its environment.
The knowledge of the geometrical structure helps conservation science to better understand production and decay reactions and to allow for full quantitative analysis in the frequent case of mixtures.

Modern high resolution X-ray powder diffraction (XRPD) in the laboratory is used as an efficient tool to determine crystal structures of long-known corrosion products on historic objects.

Diffrazione di raggi X Polvere in Conservazione Scienza: verso Routine di cristallo Struttura Determinazione di corrosione prodotti sul patrimonio Art Objects

The crystal structure determination and refinement process of corrosion products on historic art objects using laboratory high-resolution X-ray powder ...

Measurement of Particle Size Distribution in Turbid Solutions by Dynamic Light Scattering Microscopy

A protocol for measuring polydispersity of concentrated polymer solutions using dynamic light scattering is described. Dynamic light scattering is a technique used to measure the size distribution of polymer solutions or colloidal particles. Although this technique is widely used for the assessment of polymer solutions, it is difficult to measure the particle size in concentrated solutions due to the multiple scattering effect or strong light absorption. Therefore, the concentrated solutions should be diluted before measurement. Implementation of the confocal optical component in a dynamic light scattering microscope1 helps to overcome this barrier. Using such a microscopic system, both transparent and turbid systems can be analyzed under the same experimental setup without a dilution. As a representative example, a size distribution measurement of a temperature-responsive polymer solution was performed. The sizes of the polymer chains in an aqueous solution were several tens of nanometers at a temperature below the lower critical solution temperature (LCST). In contrast, the sizes increased to more than 1.0 &#181;m when above the LCST. This result is consistent with the observation that the solution turned turbid above the LCST.

A protocol for the direct measurement of particle size distribution in concentrated solutions using dynamic light scattering microscopy is presented.

Misura della dimensione delle particelle di distribuzione in torbidi soluzioni da Dynamic Light Scattering Microscopia

A protocol for measuring polydispersity of concentrated polymer solutions using dynamic light scattering is described. Dynamic light scattering is a ...

Integration of Miniaturized Solid Phase Extraction and LC-MS/MS Detection of 3-Nitrotyrosine in Human Urine for Clinical Applications

Free 3-nitrotyrosine (3-NT) has been extensively used as a possible biomarker for oxidative stress. Increased levels of 3-NT have been reported in a wide variety of pathological conditions. However, existing methods lack the sufficient sensitivity and/or specificity necessary to measure the low endogenous level of 3-NT reliably and are too cumbersome for clinical applications. Hence, analytical improvement is urgently needed to accurately quantify the levels of 3-NT and verify the role of 3-NT in pathological conditions. This protocol presents the development of a novel liquid chromatography tandem mass spectrometry (LC-MS/MS) detection combined with a miniaturized solid phase extraction (SPE) for the rapid and accurate measurement of 3-NT in human urine as a non-invasive biomarker for oxidative stress. SPE using a 96-well plate markedly simplified the process by combining sample cleanup and analyte enrichment without tedious derivatization and evaporation steps, reducing solvent consumption, waste disposal, risk of contamination and overall processing time. The employment of 25 mM ammonium acetate (NH4OAc) at pH 9 as the SPE elution solution substantially enhanced the selectivity. Mass spectrometry signal response was improved through adjustment of the multiple reaction monitoring (MRM) transitions. Use of 0.01% HCOOH as additive on a pentafluorophenyl (PFP) column (150 mm x 2.1 mm, 3 &#181;m) improved signal response another 2.5-fold and shortened the overall run time to 7 min. A lower limit of quantitation (LLOQ) of 10 pg/mL (0.044 nM) was achieved, representing a significant sensitivity improvement over the reported assays. This simplified, rapid, selective and sensitive method allows two plates of urine samples (n = 192) to be processed in a 24 h time-period. Considering the markedly improved analytical performance, and non-invasive and inexpensive urine sampling, the proposed assay is beneficial for pre-clinical and clinical studies.

A selective and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method coupled with an efficient solid phase extraction on a mixed-mode cation-exchange (MCX) 96-well microplate was developed for the measurement of free 3-nitrotyrosine (3-NT) in human urine with high throughput, which is suitable for clinical applications.

Integrazione di estrazione miniaturizzata di fase solida e rilevazione LC-MS / MS di 3-Nitrotirosina nell&#39;urina umana per applicazioni cliniche

Free 3-nitrotyrosine (3-NT) has been extensively used as a possible biomarker for oxidative stress. Increased levels of 3-NT have been reported in a wide ...

Application and Methodology of the Non-destructive 19F Time-domain NMR Technique to Measure the Content in Fluorine-containing Drug Products

Here, we describe a protocol developed by our group that uses low-field fluorine-19 (19F) time-domain (TD) nuclear magnetic resonance (NMR) to measure the average content of fluorinated drugs in their formulated drug product forms: tablets or capsules. This method is specific to fluorinated drugs because it detects only the content of fluorine, avoiding interference from the excipients that lack fluorine. The advantages of measuring the active content of fluorinated drugs using low-field 19F TD-NMR versus high-field 19F solid-state (SS) NMR are the simplicity of the method; the low cost; and the non-destructive nature of the technique, with all samples recoverable in intact forms (e.g., powders, tablets, and capsules), making this technique affordable for any laboratory.
We have tested the method with three fluorinated drug products available on the market - cinacalcet, lansoprazole, and ciprofloxacin - with doses ranging from 15 to 500 mg. The results of the analyses, measured by low-field 19F TD-NMR, supported the reported label claims for the average drug content.
Based on the simplicity and reproducibility of the analysis, we envision this methodology being implemented in any laboratory, including manufacturing plants, as a process analytical technology (PAT) tool in the pharmaceutical industry.

Application and Methodology of the Non-destructive 19F Time-domain NMR Technique to Measure the Content in Fluorine-containing Drug Products

A simple and non-destructive technique that measures the average content of drug substances in formulated drug products containing fluorine using low-field fluorine-19 (19F) time-domain (TD) nuclear magnetic resonance (NMR) is presented here. The technique can be applied to the development and manufacturing of drugs in the pharmaceutical industry.

Applicazione e metodologia della tecnica NMR Non distruttivo 19F dominio del tempo per misurare il contenuto in prodotti contenenti fluoro di droga

Here, we describe a protocol developed by our group that uses low-field fluorine-19 (19F) time-domain (TD) nuclear magnetic resonance (NMR) to measure the ...

Phase Behavior of Charged Vesicles Under Symmetric and Asymmetric Solution Conditions Monitored with Fluorescence Microscopy

Phase-separated giant unilamellar vesicles (GUVs) exhibiting coexisting liquid-ordered and liquid-disordered domains are a common biophysical tool to investigate the lipid raft hypothesis. Numerous studies, however, neglect the impact of physiological solution conditions. On that account, the current work presents the effect of high-salinity buffer and trans-membrane solution asymmetry on liquid-liquid phase separation in charged GUVs grown from dioleylphosphatidylglycerol, egg sphingomyelin, and cholesterol. The effects were studied under isothermal and varying temperature conditions.
We describe equipment and experimental strategies applicable for monitoring the stability of coexisting liquid domains in charged vesicles under symmetric and asymmetric high-salinity solution conditions. This includes an approach to prepare charged multicomponent GUVs in high-salinity buffer at high temperatures. The protocol entails the option to perform a partial exchange of the external solution by a simple dilution step while minimizing the vesicle dilution. An alternative approach is presented utilizing a microfluidic device that allows for a complete external solution exchange. The solution effects on phase separation were also studied under varying temperatures. To this end, we present the basic design and utility of an in-house built temperature control chamber. Furthermore, we reflect on the assessment of the GUV phase state, pitfalls associated with it and how to circumvent them.

Experiments on phase separated giant unilamellar vesicles (GUVs) frequently neglect physiological solution conditions. This work presents approaches to study the effect of high-salinity buffer on liquid-liquid phase separation in charged multicomponent GUVs as a function of trans-membrane solution asymmetry and temperature.

Comportamento di fase di caricate vescicole sotto soluzione simmetrica e asimmetrica condizioni monitorate con microscopia di fluorescenza

Phase-separated giant unilamellar vesicles (GUVs) exhibiting coexisting liquid-ordered and liquid-disordered domains are a common biophysical tool to ...

Protocol for the Solid-phase Synthesis of Oligomers of RNA Containing a 2'-O-thiophenylmethyl Modification and Characterization via Circular Dichroism

Solid-phase synthesis has been used to obtain canonical and modified polymers of nucleic acids, specifically of DNA or RNA, which has made it a popular methodology for applications in various fields and for different research purposes. The procedure described herein focuses on the synthesis, purification, and characterization of dodecamers of RNA 5&#39;-[CUA CGG AAU CAU]-3&#39; containing zero, one, or two modifications located at the C2&#39;-O-position. The probes are based on 2-thiophenylmethyl groups, incorporated into RNA nucleotides via standard organic synthesis and introduced into the corresponding oligonucleotides via their respective phosphoramidites. This report makes use of phosphoramidite chemistry via the four canonical nucleobases (Uridine (U), Cytosine (C), Guanosine (G), Adenosine (A)), as well as 2-thiophenylmethyl functionalized nucleotides modified at the 2&#39;-O-position; however, the methodology is amenable for a large variety of modifications that have been developed over the years. The oligonucleotides were synthesized on a controlled-pore glass (CPG) support followed by cleavage from the resin and deprotection under standard conditions, i.e., a mixture of ammonia and methylamine (AMA) followed by hydrogen fluoride/triethylamine/N-methylpyrrolidinone. The corresponding oligonucleotides were purified via polyacrylamide electrophoresis (20% denaturing) followed by elution, desalting, and isolation via reversed-phase chromatography (Sep-pak, C18-column). Quantification and structural parameters were assessed via ultraviolet-visible (UV-vis) and circular dichroism (CD) photometric analysis, respectively. This report aims to serve as a resource and guide for beginner and expert researchers interested in embarking in this field. It is expected to serve as a work-in-progress as new technologies and methodologies are developed. The description of the methodologies and techniques within this document correspond to a DNA/RNA synthesizer (refurbished and purchased in 2013) that uses phosphoramidite chemistry.

Protocol for the Solid-phase Synthesis of Oligomers of RNA Containing a 2&#039;-O-thiophenylmethyl Modification and Characterization via Circular Dichroism

This article provides a detailed procedure on the solid-phase synthesis, purification, and characterization of dodecamers of RNA modified at the C2&#39;-O-position. UV-vis and circular dichroism photometric analyses are used to quantify and characterize structural aspects, i.e., single-strands or double-strands.

Protocollo per la sintesi in fase solida di oligomeri di RNA contenente un 2&#39;-<em&gt; O</em&gt; -thiophenylmethyl Modifica e caratterizzazione attraverso il Dicroroo circolare

Solid-phase synthesis has been used to obtain canonical and modified polymers of nucleic acids, specifically of DNA or RNA, which has made it a popular ...

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight (MALDI-TOF) Mass Spectrometry

There are many techniques that can be employed in the characterization of synthetic homopolymers, but few provide as useful of information for end group analysis as matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). This tutorial demonstrates methods for optimization of the sample preparation, spectral acquisition, and data analysis of synthetic polymers using MALDI-TOF MS. Critical parameters during sample preparation include the selection of the matrix, identification of an appropriate cationization salt, and tuning the relative proportions of the matrix, cation, and analyte. The acquisition parameters, such as mode (linear or reflector), polarization (positive or negative), acceleration voltage, and delay time, are also important. Given some knowledge of the chemistry involved to synthesize the polymer and optimizing both the data acquisition parameters and the sample preparation conditions, spectra should be obtained with sufficient resolution and mass accuracy to enable the unambiguous determination of the end groups of most homopolymers (masses below 10,000) in addition to the repeat unit mass and the overall molecular weight distribution. Though demonstrated on a limited set of polymers, these general techniques are applicable to a much wider range of synthetic polymers for determining mass distributions, though end group determination is only possible for homopolymers with narrow dispersity.

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight MALDI-TOF Mass Spectrometry

A protocol for the matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) characterization of synthetic polymers is described including the optimization of sample preparation, spectral acquisition, and data analysis.

Caratterizzazione di polimeri sintetici tramite matrice assistita Laser desorbimento ionizzazione tempo di spettrometria di massa (MALDI-TOF) di volo

There are many techniques that can be employed in the characterization of synthetic homopolymers, but few provide as useful of information for end group ...

Solid-phase Synthesis of [4.4] Spirocyclic Oximes

A convenient synthetic route for spirocyclic heterocycles is well sought after due to the molecule&#39;s potential use in biological systems. By means of solid-phase synthesis, regenerating Michael (REM) linker strategies, and 1,3-dipolar cycloaddition, a library of structurally similar heterocycles, both with and without a spirocyclic center, can be constructed. The main advantages of the solid-support synthesis are as follows: first, each reaction step can be driven to completion using a large excess of reagents resulting in high yields; next, the use of commercially available starting materials and reagents keep the costs low; finally, the reaction steps are easy to purify via simple filtration. The REM linker strategy is attractive because of its recyclability and traceless nature. Once a reaction scheme is completed, the linker can be reused multiple times. In a typical solid-phase synthesis, the product contains either a part of or the whole linker, which can prove undesirable. The REM linker is &#34;traceless&#34; and the point of attachment between the product and the polymer is indistinguishable. The high diastereoselectivity of the intramolecular 1,3-dipolar cycloaddition is well documented. Limited by the insolubility of the solid support, the reaction progression can only be monitored by a change in the functional groups (if any) via infrared (IR) spectroscopy. Thus, the structural identification of intermediates cannot be characterized by conventional nuclear magnetic resonance (NMR) spectroscopy. Other limitations to this method stem from the compatibilities of the polymer/linker to the desired chemical reaction scheme. Herein we report a protocol that allows for the convenient production of spirocyclic heterocycles that, with simple modifications, can be automated with high-throughput techniques.

Here we present a protocol to demonstrate an efficient method for the synthesis of spirocyclic heterocycles. The five-step process utilizes solid-phase synthesis and regenerating Michael linker strategies. Generally difficult to synthesize, we present a customizable method for the synthesis of spirocyclic molecules otherwise inaccessible to other modern approaches.

Sintesi in fase solida di [4,4] Spirocyclic ossime

A convenient synthetic route for spirocyclic heterocycles is well sought after due to the molecule&#39;s potential use in biological systems. By means of ...

Metodologia sintetico per Asymmetric Ferrocene derivati ​​sistemi bio-coniugati attraverso Solid Metodologia Resina a base di fase

Metodologia sintetico per Asymmetric Ferrocene derivati sistemi bio-coniugati attraverso Solid Metodologia Resina a base di fase