The financial support of the Max-Planck Society, the Turkish Ministry of National Education (PhD fellowship to S. G.), and the German Exchange Academic Service (DAAD, PhD fellowship to T. S.) are gratefully acknowledged.

<ol>
	<li>Merbach, A. E., Helm, L., T&#243;th, &. #. 2. 0. 1. ;. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The chemistry of contrast agents in medical magnetic resonance imaging. 2nd ed. , (2013).</li><li>Geraldes, C. F. G. C., Laurent, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Classification+and+basic+properties+of+contrast+agents+for+magnetic+resonance+imaging.">Classification and basic properties of contrast agents for magnetic resonance imaging.</a> Contrast Media Mol. Imaging. 4 (1), 1-23 (2009).</li><li>Caravan, P., Ellison, J. J., McMurry, T. J., Lauffer, R. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gadolinium(III)+chelates+as+MRI+contrast+agents:+Structure,+dynamics,+and+applications.">Gadolinium(III) chelates as MRI contrast agents: Structure, dynamics, and applications.</a> Chem. Rev. 99 (9), 2293-2352 (1999).</li><li>Villaraza, A. J. L., Bumb, A., Brechbiel, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Macromolecules,+Dendrimers,+and+Nanomaterials+in+Magnetic+Resonance+Imaging:+The+Interplay+between+Size,+Function,+and+Pharmacokinetics.">Macromolecules, Dendrimers, and Nanomaterials in Magnetic Resonance Imaging: The Interplay between Size, Function, and Pharmacokinetics.</a> Chem. Rev. 110 (5), 2921-2959 (2010).</li><li>Langereis, S., Dirksen, A., Hackeng, T. M., van Genderen, M. H. P., Meijer, E. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dendrimers+and+magnetic+resonance+imaging.">Dendrimers and magnetic resonance imaging.</a> New J. Chem. 31 (7), 1152-1160 (2007).</li><li>G&#252;nd&#252;z, S., Power, A., Maier, M. E., Logothetis, N. K., Angelovski, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+Characterization+of+a+Biotinylated+Multivalent+Targeted+Contrast+Agent.">Synthesis and Characterization of a Biotinylated Multivalent Targeted Contrast Agent.</a> ChemPlusChem. 80 (3), 612-622 (2015).</li><li>Pope, S. J. A., Kenwright, A. M., Heath, S. L., Faulkner, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+luminescence+properties+of+a+kinetically+stable+dinuclear+ytterbium+complex+with+differentiated+binding+sites.">Synthesis and luminescence properties of a kinetically stable dinuclear ytterbium complex with differentiated binding sites.</a> Chem. Commun. (13), 1550-1551 (2003).</li><li>Vibhute, S. M., 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=Synthesis+and+characterization+of+pH-sensitive,+biotinylated+MRI+contrast+agents+and+their+conjugates+with+avidin.">Synthesis and characterization of pH-sensitive, biotinylated MRI contrast agents and their conjugates with avidin.</a> Org. Biomol. Chem. 11 (8), 1294-1305 (2013).</li><li>Vogel, A. I., Furniss, B. 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> Vogel's textbook of practical organic chemistry. 5th ed. , (1989).</li><li>Lundanes, E., Reubsaet, L., Greibrokk, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Chromatography : basic principles, sample preparations and related methods. , (2013).</li><li>Barge, A., Cravotto, G., Gianolio, E., Fedeli, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+to+determine+free+Gd+and+free+ligand+in+solution+of+Gd+chelates.+A+technical+note.">How to determine free Gd and free ligand in solution of Gd chelates. A technical note.</a> Contrast Media Mol. Imaging. 1 (5), 184-188 (2006).</li><li>Keeler, 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> Understanding NMR spectroscopy. 2nd ed. , (2010).</li><li>Hillenkamp, F., Peter-Katalini&#263;, 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> MALDI MS : a practical guide to instrumentation, methods and applications. , (2007).</li><li>Peters, J. A., Huskens, J., Raber, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lanthanide+induced+shifts+and+relaxation+rate+enhancements.">Lanthanide induced shifts and relaxation rate enhancements.</a> Prog. Nucl. Magn. Reson. Spectrosc. 28, 283-350 (1996).</li><li>Averill, D. J., Garcia, J., Siriwardena-Mahanama, B. N., Vithanarachchi, S. M., Allen, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation,+Purification,+and+Characterization+of+Lanthanide+Complexes+for+Use+as+Contrast+Agents+for+Magnetic+Resonance+Imaging.">Preparation, Purification, and Characterization of Lanthanide Complexes for Use as Contrast Agents for Magnetic Resonance Imaging.</a> J. Vis. Exp. (53), e2844 (2011).</li><li>Hagberg, G. E., Scheffler, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+r1+and+r2+relaxivity+of+gadolinium-based+contrast+agents+on+the+T1-weighted+MR+signal+at+increasing+magnetic+field+strengths.">Effect of r1 and r2 relaxivity of gadolinium-based contrast agents on the T1-weighted MR signal at increasing magnetic field strengths.</a> Contrast Media Mol. Imaging. 8 (6), 456-465 (2013).</li><li>Boswell, C. A., 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=Synthesis,+characterization,+and+biological+evaluation+of+integrin+alpha(v)beta(3)-targeted+PAMAM+dendrimers.">Synthesis, characterization, and biological evaluation of integrin alpha(v)beta(3)-targeted PAMAM dendrimers.</a> Mol. Pharmaceut. 5 (4), 527-539 (2008).</li><li>Sherry, A. D., Caravan, P., Lenkinski, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primer+on+Gadolinium+Chemistry.">Primer on Gadolinium Chemistry.</a> J. Magn. Reson. Imaging. 30 (6), 1240-1248 (2009).</li><li>Caki&#263;, N., G&#252;nd&#252;z, S., Rengarasu, R., Angelovski, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthetic+strategies+for+preparation+of+cyclen-based+MRI+contrast+agents.">Synthetic strategies for preparation of cyclen-based MRI contrast agents.</a> Tetrahedron Lett. 56 (6), 759-765 (2015).</li><li>Polasek, M., Hermann, P., Peters, J. A., Geraldes, C. F. G. C., Lukes, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PAMAM+Dendrimers+Conjugated+with+an+Uncharged+Gadolinium(III)+Chelate+with+a+Fast+Water+Exchange:+The+Influence+of+Chelate+Charge+on+Rotational+Dynamics.">PAMAM Dendrimers Conjugated with an Uncharged Gadolinium(III) Chelate with a Fast Water Exchange: The Influence of Chelate Charge on Rotational Dynamics.</a> Bioconjugate Chem. 20 (11), 2142-2153 (2009).</li><li>Ali, M. M., 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=Synthesis+and+relaxometric+studies+of+a+dendrimer-based+pH-responsive+MRI+contrast+agent.">Synthesis and relaxometric studies of a dendrimer-based pH-responsive MRI contrast agent.</a> Chem. Eur. J. 14 (24), 7250-7258 (2008).</li><li>Jackson, C. L., 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=Visualization+of+dendrimer+molecules+by+transmission+electron+microscopy+(TEM):+Staining+methods+and+Cryo-TEM+of+vitrified+solutions.">Visualization of dendrimer molecules by transmission electron microscopy (TEM): Staining methods and Cryo-TEM of vitrified solutions.</a> Macromolecules. 31 (18), 6259-6265 (1998).</li><li>Jain, K., Kesharwani, P., Gupta, U., Jain, N. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dendrimer+toxicity:+Let's+meet+the+challenge.">Dendrimer toxicity: Let's meet the challenge.</a> Int. J. Pharm. 394 (1-2), 122-142 (2010).</li><li>Rudovsky, 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=PAMAM+dendrimeric+conjugates+with+a+Gd-DOTA+phosphinate+derivative+and+their+adducts+with+polyaminoacids:+The+interplay+of+global+motion,+internal+rotation,+and+fast+water+exchange.">PAMAM dendrimeric conjugates with a Gd-DOTA phosphinate derivative and their adducts with polyaminoacids: The interplay of global motion, internal rotation, and fast water exchange.</a> Bioconjugate Chem. 17 (4), 975-987 (2006).</li><li>Xu, 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=Toward+improved+syntheses+of+dendrimer-based+magnetic+resonance+imaging+contrast+agents:+New+bifunctional+diethylenetriaminepentaacetic+acid+ligands+and+nonaqueous+conjugation+chemistry.">Toward improved syntheses of dendrimer-based magnetic resonance imaging contrast agents: New bifunctional diethylenetriaminepentaacetic acid ligands and nonaqueous conjugation chemistry.</a> J. Med. Chem. 50 (14), 3185-3193 (2007).</li><li>Nwe, K., Bryant, L. H., Brechbiel, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Poly(amidoamine)+Dendrimer+Based+MRI+Contrast+Agents+Exhibiting+Enhanced+Relaxivities+Derived+via+Metal+Preligation+Techniques.">Poly(amidoamine) Dendrimer Based MRI Contrast Agents Exhibiting Enhanced Relaxivities Derived via Metal Preligation Techniques.</a> Bioconjugate Chem. 21 (6), 1014-1017 (2010).</li><li>Livramento, J. B., 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=First+in+vivo+MRI+assessment+of+a+self-assembled+metallostar+compound+endowed+with+a+remarkable+high+field+relaxivity.">First in vivo MRI assessment of a self-assembled metallostar compound endowed with a remarkable high field relaxivity.</a> Contrast Media Mol. Imaging. 1 (1), 30-39 (2006).</li><li>Norek, M., Kampert, E., Zeitler, U., Peters, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tuning+of+the+Size+of+Dy2O3+Nanoparticles+for+Optimal+Performance+as+an+MRI+Contrast+Agent.">Tuning of the Size of Dy2O3 Nanoparticles for Optimal Performance as an MRI Contrast Agent.</a> J. Am. Chem. Soc. 130 (15), 5335-5340 (2008).</li></ol>

The authors have nothing to disclose.

Preparazione del mezzo di contrasto MRI dendrimerica richiede appropriata selezione dell&#39;unità monomerica (cioè, il chelante per Gd (III)). Essi riducono la tossicità di questo ione paramagnetico e, ad oggi, una grande varietà di aciclici e chelanti macrociclici servire a questo scopo 1-3. Tra questi, macrociclici DOTA tipo chelanti possiedono la massima stabilità termodinamica e cinetica inerzia e, quindi, sono la scelta più preferito per la preparazione di agenti di contrasto per MRI iner...

La risonanza magnetica (MRI) è una tecnica di imaging potente e non ionizzanti ampiamente utilizzato nella ricerca biomedica e diagnostica clinica per la sua natura non invasiva e un eccellente contrasto dei tessuti molli intrinseca. I metodi MRI più comunemente utilizzati utilizzano il segnale ottenuto da protoni dell&#39;acqua, fornendo immagini ad alta risoluzione e informazioni dettagliate all&#39;interno dei tessuti a base di differenze di densità dei segnali acqua. L&#39;intensità del segnale e la specificità degli esperimenti di risonanza magnetica possono essere ulteriormente migliorate utilizzando mezzi di contrasto (CA). Questi sono specie paramagnetiche o superparamagnetiche che influenzano il longitudinale (T 1) e trasversale (T 2) tempi di rilassamento, rispettivamente 1,2. Complessi di lantanidi gadolinio ionico con poliamminici ligandi acidi policarbossilici sono i più comunemente usati T 1 CA. Gadolinio (III) accorcia il rilassamento T 1tempo di protoni dell&#39;acqua, aumentando così il contrasto del segnale in esperimenti MRI 3. Tuttavia, gadolinio ionica è tossico; le sue dimensioni approssima quella del calcio (II), e colpisce seriamente calcio assistita segnalazione nelle cellule. Pertanto, aciclici e macrociclici chelati sono impiegati per neutralizzare questa tossicità. Vari leganti multidentati sono stati sviluppati finora, con conseguente gadolinio complessi (III) con elevata stabilità termodinamica e cinetica inerzia 1. Quelli basati sul Cyclen azamacrocycle 12-membered, in particolare la sua tetracarbossilico DOTA derivata (1,4,7,10-tetraazaciclododecan-1,4,7,10-tetraacetato) sono complessi più studiati e applicati di questa classe CA. Tuttavia, GdDOTA tipo CA sono sistemi a basso peso molecolare, che mostrano alcuni svantaggi come l&#39;efficienza e basso contrasto escrezione renale veloce. Macromolecolare e polivalente CA possono essere una buona soluzione a questi problemi 4. Dal momento che CA biodistribuzione è determinata principalmente dalla loro dimensione, CA macromolecolari mostrano tempi di ritenzione molto più lunghi all&#39;interno dei tessuti. Ugualmente importante, il multivalenza di questi agenti si traduce in un aumento della concentrazione locale della sonda monomerica MR (ad esempio, complessi GdDOTA), migliorando sostanzialmente il segnale MR acquisite e la qualità della misura. I dendrimeri sono tra i ponteggi preferite per la preparazione di polivalente CA per MRI 4,5. Queste macromolecole altamente ramificate con determinate dimensioni sono inclini a varie reazioni di accoppiamento sulla loro superficie. In questo lavoro, si segnala la preparazione, purificazione e caratterizzazione di una CA dendrimerica per la risonanza magnetica costituito da un 4 (G4) poli generazione (amidoamine) (PAMAM) dendrimero accoppiato ad chelati GdDOTA-like (DCA). Descriviamo la sintesi del reattiva derivata DOTA e il suo accoppiamento con il dendrimero PAMAM. Su complessazione con Gd (III), la caratterizzazione chimico-fisica di serie Operazire di DCA è stata eseguita. Infine, gli esperimenti di risonanza magnetica sono stati eseguiti per dimostrare la capacità di DCA di produrre immagini RM con un contrasto più forte di quelli ottenuti da basso peso molecolare CA.

<table border="0" cellpadding="0" cellspacing="0" width="921">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Cyclen</td>
			<td style="width:275px;">CheMatech</td>
			<td style="width:136px;">C002</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">tert-Butyl bromoacetate&#160;</td>
			<td style="width:275px;">Alfa Aesar</td>
			<td style="width:136px;">A14917</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">N,N-Dimethylformamide</td>
			<td style="width:275px;">Fluka</td>
			<td style="width:136px;">40248</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Potassium carbonate</td>
			<td style="width:275px;">Sigma-Aldrich</td>
			<td style="width:136px;">209619</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">4-(4-Nitrophenyl)butryic acid</td>
			<td style="width:275px;">Aldrich</td>
			<td style="width:136px;">335339</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:251px;">Thionyl chloride&#160;</td>
			<td style="width:275px;">Acros Organics</td>
			<td style="width:136px;">382662500</td>
			<td style="width:259px;">Note: Corrosive substance; toxic if inhaled</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:251px;">Bromine</td>
			<td style="width:275px;">Acros Organics</td>
			<td style="width:136px;">402841000</td>
			<td style="width:259px;">Note: causes severe skin burns, fatal if inhaled&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Diethyl ether</td>
			<td style="width:275px;">any source</td>
			<td style="width:136px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Sodium sulphate</td>
			<td style="width:275px;">Acros Organics</td>
			<td style="width:136px;">196640010</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Chloroform&#160;</td>
			<td style="width:275px;">VWR Chemicals</td>
			<td style="width:136px;">22711.29</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:251px;">tert-Butyl 2,2,2-trichloroacetimidate</td>
			<td style="width:275px;">Aldrich</td>
			<td style="width:136px;">364789</td>
			<td style="width:259px;">Note: flammable substance; irritrant to skin and eyes</td>
		</tr>
		<tr height="67">
			<td height="67" style="height:67px;width:251px;">Boron trifluoride etherate</td>
			<td style="width:275px;">Acros Organics</td>
			<td style="width:136px;">174560250</td>
			<td style="width:259px;">48 % BF3. Note: Flammable substance; causes skin burns, fatal if inhaled&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Sodium bicarbonate</td>
			<td style="width:275px;">Acros Organics</td>
			<td style="width:136px;">424270010</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Ethyl-acetate</td>
			<td style="width:275px;">any source</td>
			<td style="width:136px;"></td>
			<td>For column chromatography</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">n-Hexane</td>
			<td style="width:275px;">any source</td>
			<td style="width:136px;"></td>
			<td>For column chromatography</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:251px;">Bulb-to-bulb (Kugelrohr) distillation apparatus</td>
			<td style="width:275px;">B&#252;chi</td>
			<td style="width:136px;"></td>
			<td>Model type: Glass oven B-585</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Silicagel</td>
			<td style="width:275px;">Carl Roth GmbH</td>
			<td style="width:136px;">P090.2</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Methanol</td>
			<td style="width:275px;">any source</td>
			<td style="width:136px;"></td>
			<td>For column chromatography</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Dichloromethane&#160;</td>
			<td style="width:275px;">any source</td>
			<td style="width:136px;"></td>
			<td>For column chromatography</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Ethanol</td>
			<td style="width:275px;">VWR Chemicals</td>
			<td style="width:136px;">20821.296</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Ammonia</td>
			<td style="width:275px;">Acros Organics</td>
			<td style="width:136px;">428381000</td>
			<td style="width:259px;">7N Solution in Methanol</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Palladium&#160;</td>
			<td style="width:275px;">Aldrich</td>
			<td style="width:136px;">643181</td>
			<td style="width:259px;">15 % wet</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Hydrogenation apparatus PARR</td>
			<td style="width:275px;">PARR Instrument Company</td>
			<td style="width:136px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Celite 503</td>
			<td style="width:275px;">Aldrich</td>
			<td style="width:136px;">22151</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Sintered glass funnel</td>
			<td style="width:275px;">any source</td>
			<td style="width:136px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Thiophosgen</td>
			<td style="width:275px;">Aldrich</td>
			<td style="width:136px;">115150</td>
			<td style="width:259px;">Note: irritrant to skin; toxic if inhaled</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Triethylamine</td>
			<td style="width:275px;">Alfa Aesar</td>
			<td style="width:136px;">A12646</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Dichloromethane&#160;</td>
			<td style="width:275px;">Acros Organics</td>
			<td style="width:136px;">348460010</td>
			<td style="width:259px;">Extra dry&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Magnetic stirrer</td>
			<td style="width:275px;">any source</td>
			<td style="width:136px;"></td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">PAMAM G4 Dendrimer</td>
			<td style="width:275px;">Andrews ChemService</td>
			<td style="width:136px;">AuCS - 297</td>
			<td style="width:259px;">&#160;10 % wt. solution in MeOH</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Lipophylic Sephadex LH-20</td>
			<td style="width:275px;">Sigma</td>
			<td style="width:136px;">LH20100</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Thin-layer chromatography plates</td>
			<td style="width:275px;">Merck Millipore</td>
			<td style="width:136px;">1.05554.0001</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Formic acid</td>
			<td style="width:275px;">VWR Chemicals</td>
			<td style="width:136px;">20318.297</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Lophylizer&#160;</td>
			<td style="width:275px;">any source</td>
			<td style="width:136px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:251px;">Gadollinium(III) chloride hexahydrate</td>
			<td style="width:275px;">Aldrich</td>
			<td style="width:136px;">G7532</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Sodium hydroxide</td>
			<td style="width:275px;">Acros Organics</td>
			<td style="width:136px;">134070010</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">pH meter</td>
			<td style="width:275px;">any source</td>
			<td style="width:136px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:251px;">Ethylenediaminetetraacetic acid disodium salt dihydrate</td>
			<td style="width:275px;">Aldrich</td>
			<td style="width:136px;">E5134</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Mass spectrometer (ESI)</td>
			<td style="width:275px;">Agilent</td>
			<td style="width:136px;"></td>
			<td>Ion trap SL 1100&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Acetate buffer</td>
			<td style="width:275px;">any source</td>
			<td style="width:136px;"></td>
			<td>pH 5.8</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Xylenol orange</td>
			<td style="width:275px;">Aldrich</td>
			<td style="width:136px;">52097</td>
			<td>20 &#956;M in acetate buffer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Hydrophylic Sephadex G-15</td>
			<td style="width:275px;">GE Healthcare</td>
			<td style="width:136px;">17-0020-01</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:251px;">Amicon Ultra-15 Centrifugal Filter Unit</td>
			<td style="width:275px;">Merck Millipore</td>
			<td style="width:136px;">UFC900324</td>
			<td style="width:259px;">Ultracel-3 membrane (MWCO 3000)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Centrifuge</td>
			<td style="width:275px;">any source</td>
			<td style="width:136px;"></td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">NMR spectrometer&#160;</td>
			<td style="width:275px;">Bruker</td>
			<td style="width:136px;"></td>
			<td style="width:259px;">Avance III 300 MHz</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Topspin</td>
			<td style="width:275px;">Bruker</td>
			<td style="width:136px;"></td>
			<td style="width:259px;">version 2.1</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Combustion analysis instrument</td>
			<td style="width:275px;">EuroVector SpA</td>
			<td style="width:136px;"></td>
			<td style="width:259px;">EuroEA 3000 Elemental Analyser&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">MALDI-ToF MS instrument</td>
			<td style="width:275px;">Applied Biosystems</td>
			<td style="width:136px;"></td>
			<td style="width:259px;">Voyager-STR</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Deuteriumoxid</td>
			<td style="width:275px;">Carl Roth GmbH</td>
			<td style="width:136px;">6672.3</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">tert-Butyl alcohol</td>
			<td style="width:275px;">Carl Roth GmbH</td>
			<td style="width:136px;">AE16.1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Vortex mixer</td>
			<td style="width:275px;">any source</td>
			<td style="width:136px;"></td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Norell NMR tubes</td>
			<td style="width:275px;">Deutero GmbH</td>
			<td style="width:136px;">507-HP-7</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">NMR coaxial tube</td>
			<td style="width:275px;">Deutero GmbH</td>
			<td style="width:136px;">coaxialb-5-7</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">DLS instrument</td>
			<td style="width:275px;">Malvern</td>
			<td style="width:136px;"></td>
			<td style="width:259px;">Zetasizer Nano ZS</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">0.20 &#956;m PTFE filter&#160;</td>
			<td style="width:275px;">Carl Roth GmbH</td>
			<td style="width:136px;">KC94.1</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">HEPES</td>
			<td style="width:275px;">Fisher BioReagents</td>
			<td style="width:136px;">BP310</td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Plastic tube vials</td>
			<td style="width:275px;">any source</td>
			<td style="width:136px;"></td>
			<td style="width:259px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Dotarem</td>
			<td style="width:275px;">Guerbet</td>
			<td style="width:136px;"></td>
			<td style="width:259px;">NDC 67684-2000-1</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:251px;">MRI scanner</td>
			<td style="width:275px;">Bruker</td>
			<td style="width:136px;"></td>
			<td style="width:259px;">BioSpec 70/30 USR magnet (7 T). Note: potential hazards related to high magnetic fields</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:251px;">RF coil</td>
			<td style="width:275px;">Bruker</td>
			<td style="width:136px;"></td>
			<td style="width:259px;">dual frequency volume coil (RF RES 300 1H/19F 075/040 LIN/LIN TR)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Paravision (software)</td>
			<td style="width:275px;">Bruker</td>
			<td style="width:136px;"></td>
			<td style="width:259px;">Version 5.1</td>
		</tr>
	</tbody>
</table>

preparation and in vitro characterization of dendrimer-based contrast agents for magnetic resonance imaging

complessi paramagnetici di gadolinio (III) con aciclico o chelati macrociclici sono gli agenti di contrasto più comunemente usati (CAS) per la risonanza magnetica (MRI). Il loro scopo è quello di migliorare la velocità di rilassamento dei protoni dell&#39;acqua nel tessuto, aumentando così il contrasto dell&#39;immagine MR e la specificità delle misurazioni MRI. mezzi di contrasto clinicamente approvati attuali sono molecole a basso peso molecolare che sono rapidamente eliminato dal corpo. L&#39;utilizzo di dendrimeri come portatori di chelanti paramagnetiche possono giocare un ruolo importante nel futuro sviluppo di agenti di contrasto per MRI più efficienti. In particolare, l&#39;aumento della concentrazione locale dei paramagnetici risultati specie in contrasto segnale più alto. Inoltre, questa CA fornisce un tempo di ritenzione del tessuto più grazie al suo elevato peso e dimensione molecolare. Qui, dimostriamo un procedimento conveniente per la preparazione di agenti di contrasto MRI macromolecolari a base di poli (amidoamine) (PAMAM) dendrimeri con monomacrociclici DOTA tipo chelanti (DOTA - 1,4,7,10-tetraazaciclododecan-1,4,7,10-tetraacetato). L&#39;unità chelante è stato aggiunto sfruttando la reattività del gruppo isotiocianato (NCS) verso i gruppi superficiali ammina del dendrimero PAMAM per formare ponti tiourea. prodotti dendrimerici sono stati purificati e analizzati mediante spettroscopia di risonanza magnetica nucleare, spettrometria di massa e analisi elementare. Infine, ad alta risoluzione immagini RM sono state registrate e contrasti segnale ottenuto dal dendrimero preparato e agenti monomeriche disponibili in commercio sono stati confrontati.

La preparazione di DCA consisteva di due fasi: 1) sintesi del monomero DOTA-tipo chelante (Figura 1) e 2) accoppiamento del chelante con il dendrimero G4 PAMAM e successiva preparazione del dendrimero Gd (III) (Figura 2) . Nella prima fase, è stato preparato un cyclen basato DOTA-tipo chelante contenente quattro acidi carbossilici e un gruppo ortogonale adatto per ulteriori modifiche sintetici. La preparazione iniziata da 1</str...

Watch this Scientific Journal Video about Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging at JoVE.com

Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging

Questo protocollo descrive la preparazione e caratterizzazione di un agente di contrasto dendrimerica risonanza magnetica (MRI) che porta chelati macrociclici cyclen basati coordinamento ioni paramagnetici gadolinio. In una serie di esperimenti in vitro MRI, questo agente prodotto un segnale RM amplificato rispetto all&#39;analogo monomerica disponibile in commercio.

Preparazione e<em&gt; In Vitro</em&gt; Caratterizzazione del dendrimero a base di agenti di contrasto per risonanza magnetica

Paramagnetic complexes of gadolinium(III) with acyclic or macrocyclic chelates are the most commonly used contrast agents (CAs) for magnetic resonance ...

preparation-vitro-characterization-dendrimer-based-contrast-agents

Research

JoVE Journal

Chemistry

Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging

9.8K Views.  Max Planck Institute for Biological Cybernetics.  Questo protocollo descrive la preparazione e caratterizzazione di un agente di contrasto dendrimerica risonanza magnetica (MRI) che porta chelati macrociclici cyclen basati coordinamento ioni paramagnetici gadolinio. In una serie di esperimenti in vitro MRI, questo agente prodotto un segnale RM amplificato rispetto all'analogo monomerica disponibile in commercio. 

Video: Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging

Synthesis, Cellular Delivery and In vivo Application of Dendrimer-based pH Sensors

The development of fluorescent indicators represented a revolution for life sciences. Genetically encoded and synthetic fluorophores with sensing abilities allowed the visualization of biologically relevant species with high spatial and temporal resolution. Synthetic dyes are of particular interest thanks to their high tunability and the wide range of measureable analytes. However, these molecules suffer several limitations related to small molecule behavior (poor solubility, difficulties in targeting, often no ratiometric imaging allowed). In this work we introduce the development of dendrimer-based sensors and present a procedure for pH measurement in vitro, in living cells and in vivo. We choose dendrimers as ideal platform for our sensors for their many desirable properties (monodispersity, tunable properties, multivalency) that made them a widely used scaffold for several biomedical devices. The conjugation of fluorescent pH indicators to the dendrimer scaffold led to an enhancement of their sensing performances. In particular dendrimers exhibit reduced cell leakage, improved intracellular targeting and allow ratiometric measurements. These novel sensors were successfully employed to measure pH in living HeLa cells and in vivo in mouse brain.

Synthesis, Cellular Delivery and In vivo Application of Dendrimer-based pH Sensors

Fluorescence sensors are powerful tools in life science. Here we describe a methodology to synthesize and use dendrimer-based fluorescent sensors to measure pH in living cells and in vivo. The dendritic scaffold enhances the properties of conjugated fluorescent dyes leading to improved sensing properties.

Sintesi, Consegna Cellulare e<em&gt; In vivo</em&gt; Applicazione di sensori di pH basati Dendrimero

The development of  fluorescent indicators represented a revolution for life sciences. Genetically  encoded and synthetic fluorophores with sensing ...

Ricerca

Chimica

Preparation and Characterization of SDF-1&#945;-Chitosan-Dextran Sulfate Nanoparticles

Chitosan (CS) and dextran sulfate (DS) are charged polysaccharides (glycans), which form polyelectrolyte complex-based nanoparticles when mixed under appropriate conditions. The glycan nanoparticles are useful carriers for protein factors, which facilitate the in vivo delivery of the proteins and sustain their retention in the targeted tissue. The glycan polyelectrolyte complexes are also ideal for protein delivery, as the incorporation is carried out in aqueous solution, which reduces the likelihood of inactivation of the proteins. Proteins with a heparin-binding site adhere to dextran sulfate readily, and are, in turn, stabilized by the binding. These particles are also less inflammatory and toxic when delivered in vivo. In the protocol described below, SDF-1&#945; (Stromal cell-derived factor-1&#945;), a stem cell homing factor, is first mixed and incubated with dextran sulfate. Chitosan is added to the mixture to form polyelectrolyte complexes, followed by zinc sulfate to stabilize the complexes with zinc bridges. The resultant SDF-1&#945;-DS-CS particles are measured for size (diameter) and surface charge (zeta potential). The amount of the incorporated SDF-1&#945; is determined, followed by measurements of its in vitro release rate and its chemotactic activity in a particle-bound form.

The objective of this protocol is to incorporate SDF-1&#945;, a stem cell homing factor, into dextran sulfate-chitosan nanoparticles. The resultant particles are measured for their size and zeta potential, as well as the content, activity, and in vitro release rate of SDF-1&#945; from the nanoparticles.

Preparazione e caratterizzazione di SDF-1α-Chitosan-Destrano solfato nanoparticelle

Chitosan (CS) and dextran sulfate (DS) are charged polysaccharides (glycans), which form polyelectrolyte complex-based nanoparticles when mixed under ...

Preparation and Characterization of Individual and Multi-drug Loaded Physically Entrapped Polymeric Micelles

Amphiphilic block copolymers like polyethyleneglycol-block-polylactic acid (PEG-b-PLA) can self-assemble into micelles above their critical micellar concentration forming hydrophobic cores surrounded by hydrophilic shells in aqueous environments. The core of these micelles can be utilized to load hydrophobic, poorly water soluble drugs like docetaxel (DTX) and everolimus (EVR). Systematic characterization of the micelle structure and drug loading capabilities are important before in vitro and in vivo studies can be conducted. The goal of the protocol described herein is to provide the necessary characterization steps to achieve standardized micellar products. DTX and EVR have intrinsic solubilities of 1.9 and 9.6 &#181;g/ml respectively Preparation of these micelles can be achieved through solvent casting which increases the aqueous solubility of DTX and EVR to 1.86 and 1.85 mg/ml, respectively. Drug stability in micelles evaluated at room temperature over 48 hr indicates that 97% or more of the drugs are retained in solution. Micelle size was assessed using dynamic light scattering and indicated that the size of these micelles was below 50 nm and depended on the molecular weight of the polymer. Drug release from the micelles was assessed using dialysis under sink conditions at pH 7.4 at 37 oC over 48 hr. Curve fitting results indicate that drug release is driven by a first order process indicating that it is diffusion driven.

The goal of this protocol is to describe the preparation and characterization of physically entrapped, poorly water soluble drugs in micellar drug delivery systems composed of amphiphilic block copolymers.

Preparazione e caratterizzazione di individuale e Multi-droga Loaded Fisicamente intrappolate polimerici Micelle

Amphiphilic block copolymers like polyethyleneglycol-block-polylactic acid (PEG-b-PLA) can self-assemble into micelles above their critical micellar ...

Sequencing of Plant Wall Heteroxylans Using Enzymic, Chemical (Methylation) and Physical (Mass Spectrometry, Nuclear Magnetic Resonance) Techniques

This protocol describes the specific techniques used for the characterization of reducing end (RE) and internal region glycosyl sequence(s) of heteroxylans. De-starched wheat endosperm cell walls were isolated as an alcohol-insoluble residue (AIR)1 and sequentially extracted with water (W-sol Fr) and 1 M KOH containing 1% NaBH4 (KOH-sol Fr) as described by Ratnayake et al. (2014)2. Two different approaches (see summary in Figure 1) are adopted. In the first, intact W-sol AXs are treated with 2AB to tag the original RE backbone chain sugar residue and then treated with an endoxylanase to generate a mixture of 2AB-labelled RE and internal region reducing oligosaccharides, respectively. In a second approach, the KOH-sol Fr is hydrolyzed with endoxylanase to first generate a mixture of oligosaccharides which are subsequently labelled with 2AB. The enzymically released ((un)tagged) oligosaccharides from both W- and KOH-sol Frs are then methylated and the detailed structural analysis of both the native and methylated oligosaccharides is performed using a combination of MALDI-TOF-MS, RP-HPLC-ESI-QTOF-MS and ESI-MSn. Endoxylanase digested KOH-sol AXs are also characterized by nuclear magnetic resonance (NMR) that also provides information on the anomeric configuration. These techniques can be applied to other classes of polysaccharides using the appropriate endo-hydrolases.

Sequencing of Plant Wall Heteroxylans Using Enzymic, Chemical Methylation and Physical Mass Spectrometry, Nuclear Magnetic Resonance Techniques

This protocol describes the specific techniques used for the structural characterization of reducing end (RE) and internal region glycosyl sequence(s) of heteroxylans by tagging the RE with 2 aminobenzamide prior to enzymatic (endoxylanase) hydrolysis and then analysis of the resultant oligosaccharides using mass spectrometry (MS) and nuclear magnetic resonance (NMR).

Il sequenziamento di Plant parete Heteroxylans Utilizzando enzimatica, chimica (metilazione) e (Spettrometria di Massa, Risonanza Magnetica Nucleare) tecniche fisiche

This protocol describes the specific techniques used for the characterization of reducing end (RE) and internal region glycosyl sequence(s) of ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

Sintesi e caratterizzazione di supramolecolari colloidi

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

Low-energy Cathodoluminescence for (Oxy)Nitride Phosphors

Nitride and oxynitride (Sialon) phosphors are good candidates for the ultraviolet and visible emission applications. High performance, good stability and flexibility of their emission properties can be achieved by controlling their composition and dopants. However, a lot of work is still required to improve their properties and to reduce the production cost. A possible approach is to correlate the luminescence properties of the Sialon particles with their local structural and chemical environment in order to optimize their growth parameters and find novel phosphors. For such a purpose, the low-voltage cathodoluminescence (CL) microscopy is a powerful technique. The use of electron as an excitation source allows detecting most of the luminescence centers, revealing their luminescence distribution spatially and in depth, directly comparing CL results with the other electron-based techniques, and investigating the stability of their luminescence properties under stress. Such advantages for phosphors characterization will be highlighted through examples of investigation on several Sialon phosphors by low-energy CL.

Low-energy Cathodoluminescence for OxyNitride Phosphors

An excellent chemical and luminescence stabilities of (oxy)nitride phosphors present it as an promising alternative to currently used sulfide and oxide phosphors. In this paper, we present the way to investigate its local luminescence properties using low-energy cathodoluminescence (CL).

Catodoluminescenza a basso consumo energetico per (Oxy) Fosfori nitruro

Nitride and oxynitride (Sialon) phosphors are good candidates for the ultraviolet and visible emission applications. High performance, good stability and ...

In Situ Monitoring of Diffusion of Guest Molecules in Porous Media Using Electron Paramagnetic Resonance Imaging

A method is demonstrated to monitor macroscopic translational diffusion using electron paramagnetic resonance (EPR) imaging. A host-guest system with nitroxide spin probe 3-(2-Iodoacetamido)-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (IPSL) as a guest inside the periodic mesoporous organosilica (PMO) aerogel UKON1-GEL as a host and ethanol as a solvent is used as an example to describe the protocol. Data is shown from a previous publication, where the protocol has been applied to both IPSL and Tris(8-carboxy-2,2,6,6-perdeutero-tetramethyl-benzo[1,2-d:4,5-d&#8242;]bis(1,3)dithiole) methyl (Trityl) as guest molecules and UKON1-GEL and SILICA-GEL as host systems. 
A method is shown to prepare aerogel samples that cannot be synthesized directly in the sample tube for measurement due to a size change during synthesis. The aerogel is attached to sample tubes using heat shrink tubing and a pressure cooker to reach the necessary temperature without evaporating the solvent in the process. The method does not assume a clearly defined initial distribution of guest molecules at the start of the measurement. Instead, it requires a reservoir on top of the aerogel and experimentally determines the influx rate during data analysis.
The diffusion is monitored continually over a period of 20 hr by recording the 1d spin density profile within the sample. The spectrometer settings for the imaging experiment are described quantitatively. Data analysis software is provided to take the resonator sensitivity profile into account and to numerically solve the diffusion equation. The software determines the macroscopic translational diffusion coefficient by least square minimization of the difference between the experiment and the numerical solution of the diffusion equation.

In Situ Monitoring of Diffusion of Guest Molecules in Porous Media Using Electron Paramagnetic Resonance Imaging

A protocol for the in situ monitoring of the diffusion of guest molecules in porous media using electron paramagnetic resonance (EPR) imaging is presented.

In Situ Monitoraggio della diffusione di Guest Molecole in mezzi porosi Utilizzando paramagnetica elettronica Risonanza

A method is demonstrated to monitor macroscopic translational diffusion using electron paramagnetic resonance (EPR) imaging. A host-guest system with ...

DNA-magnetic Particle Binding Analysis by Dynamic and Electrophoretic Light Scattering

Isolation of DNA using magnetic particles is a field of high importance in biotechnology and molecular biology research. This protocol describes the evaluation of DNA-magnetic particles binding via dynamic light scattering (DLS) and electrophoretic light scattering (ELS). Analysis by DLS provides valuable information on the physicochemical properties of particles including particle size, polydispersity, and zeta potential. The latter describes the surface charge of the particle which plays major role in electrostatic binding of materials such as DNA. Here, a comparative analysis exploits three chemical modifications of nanoparticles and microparticles and their effects on DNA binding and elution. Chemical modifications by branched polyethylenimine, tetraethyl orthosilicate and (3-aminopropyl)triethoxysilane are investigated. Since DNA exhibits a negative charge, it is expected that zeta potential of particle surface will decrease upon binding of DNA. Forming of clusters should also affect particle size. In order to investigate the efficiency of these particles in isolation and elution of DNA, the particles are mixed with DNA in low pH (~6), high ionic strength and dehydration environment. Particles are washed on magnet and then DNA is eluted by Tris-HCl buffer (pH = 8). DNA copy number is estimated using quantitative polymerase chain reaction (PCR). Zeta potential, particle size, polydispersity and quantitative PCR data are evaluated and compared. DLS is an insightful and supporting method of analysis that adds a new perspective to the process of screening of particles for DNA isolation.

This protocol describes the synthesis of magnetic particles and evaluation of their DNA-binding properties via dynamic and electrophoretic light scattering. This method focuses on monitoring changes in particle size, their polydispersity and zeta potential of particle surface which play major role in binding of materials such as DNA.

DNA-magnetoscopico associazione analisi di dispersione della luce dinamica ed elettroforetica

Isolation of DNA using magnetic particles is a field of high importance in biotechnology and molecular biology research. This protocol describes the ...

Preparation and Characterization of C60/Graphene Hybrid Nanostructures

Physical thermal deposition in a high vacuum environment is a clean and controllable method for fabricating novel molecular nanostructures on graphene. We present methods for depositing and passively manipulating C60 molecules on rippled graphene that advance the pursuit of realizing applications involving 1D C60/graphene hybrid structures. The techniques applied in this exposition are geared towards high vacuum systems with preparation areas capable of supporting molecular deposition as well as thermal annealing of the samples. We focus on C60 deposition at low pressure using a homemade Knudsen cell connected to a scanning tunneling microscopy (STM) system. The number of molecules deposited is regulated by controlling the temperature of the Knudsen cell and the deposition time. One-dimensional (1D) C60 chain structures with widths of two to three molecules can be prepared via tuning of the experimental conditions. The surface mobility of the C60 molecules increases with annealing temperature allowing them to move within the periodic potential of the rippled graphene. Using this mechanism, it is possible to control the transition of 1D C60 chain structures to a hexagonal close packed quasi-1D stripe structure.

Preparation and Characterization of C60/Graphene Hybrid Nanostructures

Here we present a protocol for the fabrication of C60/graphene hybrid nanostructures by physical thermal evaporation. Particularly, the proper manipulation of deposition and annealing conditions allow the control over the creation of 1D and quasi 1D C60 structures on rippled graphene.

Preparazione e caratterizzazione di nanostrutture ibride C60/Graphene

Physical thermal deposition in a high vacuum environment is a clean and controllable method for fabricating novel molecular nanostructures on graphene. We ...

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F&#8722;

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound electrons with neutral molecules/atoms. State-of-the-art in vacuo anion generation techniques allow application to a broad range of atomic, molecular, and cluster anion systems. These are separated and selected using time-of-flight mass spectrometry. Electrons are removed by linearly polarized photons (photo detachment) using table-top laser sources which provide ready access to excitation energies from the infra-red to the near ultraviolet. Detecting the photoelectrons with a velocity mapped imaging lens and position sensitive detector means that, in principle, every photoelectron reaches the detector and the detection efficiency is uniform for all kinetic energies. Photoelectron spectra extracted from the images via mathematical reconstruction using an inverse Abel transformation reveal details of the anion internal energy state distribution and the resultant neutral energy states. At low electron kinetic energy, typical resolution is sufficient to reveal energy level differences on the order of a few millielectron-volts, i.e., different vibrational levels for molecular species or spin-orbit splitting in atoms. Photoelectron angular distributions extracted from the inverse Abel transformation represent the signatures of the bound electron orbital, allowing more detailed probing of electronic structure. The spectra and angular distributions also encode details of the interactions between the outgoing electron and the residual neutral species subsequent to excitation. The technique is illustrated by the application to an atomic anion (F&#8722;), but it can also be applied to the measurement of molecular anion spectroscopy, the study of low lying anion resonances (as an alternative to scattering experiments) and femtosecond (fs) time resolved studies of the dynamic evolution of anions.

Here, we present a protocol for photoelectron imaging of anionic species. Anions generated in vacuo and separated by mass spectrometry are probed using velocity mapped photoelectron imaging, providing details of anion and neutral energy levels, anion and neutral structure and the nature of the anion electronic state.

Imaging di fotoelettroni di anioni illustrato da 310 Nm distaccamento di F−

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound ...