This material is based upon work supported by the U.S. Department of Homeland Security under Grant Award Number 2010-ST-061-FD0001 through a grant awarded by the National Center for Food Protection and Defense at the University of Minnesota. Disclaimer: The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Department of Homeland Security or the National Center for Food Protection and Defense.

1. argento delle nanoparticelle di sintesi 15 <ol><li> Sciogliere 18 mg di nitrato d&#39;argento in 100 ml di acqua ultrapura (18.2 ΩU) e vortex per 5 sec. </li><li> Sciogliere 27 mg di sodio citrato diidrato in acqua 1 ml e vortex per 5 sec. </li><li> Trasferire tutta la soluzione di nitrato d&#39;argento disposti in una beuta contenente una barra di agitazione e mettere il pallone su una piastra calda magnetica. Riscaldare il pallone sotto agitazione vigorosa con una velocità di agitazione di 700 giri al minuto a ~ 350 ° C (temperatura impostata sulla piastra). </li><li> Quando bolle, aggiungere tutta la soluzione di citrato di sodio preparato nella beuta immediatamente e lasciare la soluzione a bollire per altri 25 min fino a quando la soluzione diventa marrone verdastro, che indica la formazione di Ag NP. </li><li> Togliere il pallone dalla piastra calda e metterlo su un altro piatto magnetico (non riscaldare) e mescolare O / N alla stessa velocità di agitazione a temperatura ambiente fino a quando il composto non raggiunge uno stato stabile, con un colore costante e transparency. Utilizzare uno spettrometro UV-vis per determinare l&#39;assorbimento delle Ag NP preparati, se necessario. </li><li> Diluire la miscela finale con acqua ultrapura a 100 ml. </li><li> Utilizzare un Zetasizer per misurare le dimensioni delle nanoparticelle di Ag, se necessario, secondo il protocollo del produttore. </li><li> Trasferire il colloide Ag in un contenitore sigillato e proteggerlo dalla luce con un foglio di alluminio. Il colloide può essere conservato in frigorifero a 4-7 ° C per 2 mesi, se necessario. </li></ol> 2. Realizzazione di un SERS attivo filtro a membrana <ol><li> Sciogliere 2,92 g di cloruro di sodio (NaCl) in 100 ml di acqua per ottenere una soluzione 50 mM di NaCl. </li><li> Aggiungere 1 ml di soluzione 5 mM NaCl in 1 ml di Ag NP preparati e mescolare su un agitatore oscillante per 10 min a 20 rpm. Questo passo è quello di aggregare le NP Ag in nanoclusters AG. </li><li> Collocare una membrana filtrante (PVDF, 0,1 micron dimensione dei pori) in un portafiltro, che può essere collegato ad una siringa. La membrana dimensione dei pori più piccola era FOund più efficace rispetto alla dimensione dei pori di membrana più grandi (cioè, 0,22 micron) in intrappolamento nanocluster Ag e produrre segnali coerenti. </li><li> Carico 2 ml di nanocluster Ag preparati nella siringa per la filtrazione. Agganciare il portafiltro alla siringa e passare manualmente l&#39;intero volume di nanocluster Ag attraverso la membrana al flusso di 1 goccia / sec. I nanocluster trappole membrana Ag, formando una membrana filtrante SERS-attiva. </li><li> Staccare la membrana del filtro dal supporto del filtro. Particolare cautela è necessaria quando si tiene la membrana sul bordo esterno usando un paio di pinzette per garantire nessun danno alla membrana. Aria secca per circa 3 min e posto membrana su un vetrino. </li><li> rilevamento Raman del substrato SERS <ol><li> Impostare lo strumento Raman di un laser a lunghezza d&#39;onda di 780 nm con una potenza laser di 5 mW, tempo di esposizione di 1 secondo e l&#39;esposizione numero di 2. Impostare l&#39;obiettivo microscopico a 10 volte. Assicurarsi che l&#39;obiettivo del software è impostato di conseguenza troppo. &lt;/ Li&gt; <li> Posizionare il vetrino con la membrana in alto sulla piattaforma dello strumento Raman e utilizzare il microscopio a concentrarsi sulla superficie della membrana. </li><li> Casualmente selezionare 8-10 macchie dalla superficie della membrana e lo strumento raccoglierà automaticamente in sequenza. Aperte dati spettrali nel software del produttore per l&#39;analisi. </li></ol></li></ol> 3. Applicazione della SERS Filtro Attivo sistema di rilevare contaminanti chimici <ol><li> Preparare una soluzione ferbam 10 ppb. Attenzione: Ferbam è altamente volatile. Utilizzare precauzioni (respiratore e occhiali) nel valutare il solido. <ol><li> Pesare 2 mg polvere ferbam e scioglierlo in 20 ml 50% acetonitrile (10 ml di acetonitrile e 10 ml di acqua) per ottenere una soluzione stock (100 ppm). Agitare il pallone per 30 sec. </li><li> Prendere 1 ml di soluzione ferbam 100 ppm in una provetta e aggiungere 9 ml 50% acetonitrile per ottenere una soluzione 10 ppm. Agitare la provetta per 5 secondi. </li><li> Prendere 1 ml di10 ppm soluzione in una provetta e aggiungere 9 ml 50% acetonitrile per ottenere una soluzione 1 ppm. Agitare la provetta per 5 secondi. </li><li> Prendere 1 ml della soluzione di 1 ppm in una provetta e aggiungere 9 ml 50% acetonitrile per ottenere una soluzione di 100 ppb. Agitare la provetta per 5 secondi. </li><li> Prendere 1 ml della soluzione 100 ppb in una provetta e aggiungere 9 ml 50% acetonitrile per ottenere una soluzione 10 ppb. Agitare la provetta per 5 secondi. </li></ol></li><li> Preparare una soluzione ampicillina 1 ppm. <ol><li> Pesare 10 mg polvere ampicillina e sciogliere in 100 ml di acqua per ottenere una soluzione ampicillina 100 ppm. Agitare il pallone per 30 sec. </li><li> Prendere 1 ml della soluzione 100 ppm in una provetta e aggiungere 9 ml di acqua per ottenere una soluzione ampicillina 10 ppm. Agitare la provetta per 5 secondi. </li><li> Prendere 1 ml della soluzione di 10 ppm in una provetta e aggiungere 9 ml di acqua per ottenere una soluzione ampicillina 1 ppm. Agitare la provetta per 5 secondi. </li></ol></li><li> Mettere la membrana del filtro ai portafiltri, con il lato rivestito NP rivolto verso l&#39;alto. &lt;/ Li&gt; <li> Carico 5 ml di un campione in una nuova siringa, e poi attaccarlo al supporto del filtro con una membrana di Ag ricoperto all&#39;interno. </li><li> Far passare manualmente l&#39;intero volume del campione attraverso la membrana al flusso di 1 goccia / sec. molecole bersaglio possono essere assorbiti e concentrati sulle NP adesi alla membrana del filtro. </li><li> Sfilare membrana del filtro dal portafiltro, asciugare all&#39;aria per circa 3 minuti e misurare i segnali utilizzando lo strumento Raman utilizzando lo stesso metodo descritto al punto 2.6. </li><li> Ripetere passaggio 2.2 2.6 preparare un&#39;altra membrana Ag-rivestito, e seguire dal punto 3.3 per il rilevamento degli altri campioni. </li></ol>

<ol>
	<li>Albrecht, M. G., Creighton, 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=Anomalously+intense+Raman+spectra+of+pyridine+at+a+silver+electrode.">Anomalously intense Raman spectra of pyridine at a silver electrode.</a> J. Am. Chem. Soc. 99 (15), 5215-5217 (1977).</li><li>Schatz, G. C., Young, M. A., Van Duyne, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Electromagnetic mechanism of SERS. Surface-enhanced Raman scattering. , 19-45 (2006).</li><li>Matijevic, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+and+properties+of+uniform+size+colloids.">Preparation and properties of uniform size colloids.</a> Chem. Mater. 5 (4), 412-426 (1993).</li><li>Nickel, U., zu Castell, A., P&#246;ppl, K., Schneider, 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+silver+colloid+produced+by+reduction+with+hydrazine+as+support+for+highly+sensitive+surface-enhanced+Raman+spectroscopy.">A silver colloid produced by reduction with hydrazine as support for highly sensitive surface-enhanced Raman spectroscopy.</a> Langmuir. 16 (23), 9087-9091 (2000).</li><li>Khanna, P. K., Subbarao, V. V. V. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanosized+silver+powder+via+reduction+of+silver+nitrate+by+sodium+formaldehydesulfoxylate+in+acidic+pH+medium.">Nanosized silver powder via reduction of silver nitrate by sodium formaldehydesulfoxylate in acidic pH medium.</a> Mater. Lett. 57 (15), 2242-2245 (2003).</li><li>Henglein, A., Giersig, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Formation+of+colloidal+silver+nanoparticles:+capping+action+of+citrate.">Formation of colloidal silver nanoparticles: capping action of citrate.</a> J. Phys. Chem. B. 103 (44), 9533-9539 (1999).</li><li>Sun, X., Li, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Colloidal+carbon+spheres+and+their+core/shell+structures+with+noble-metal+nanoparticles.">Colloidal carbon spheres and their core/shell structures with noble-metal nanoparticles.</a> Angew. Chem. Int. Edit. 43 (5), 597-601 (2004).</li><li>Lu, 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=Seed-mediated+growth+of+large,+monodisperse+core-shell+gold-silver+nanoparticles+with+Ag-like+optical+properties.">Seed-mediated growth of large, monodisperse core-shell gold-silver nanoparticles with Ag-like optical properties.</a> Chem. Commun. (2), 144-145 (2002).</li><li>Aslan, K., Wu, M., Lakowicz, J. R., Geddes, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescent+core-shell+Ag@SiO2+nanocomposites+for+metal-enhanced+fluorescence+and+single+nanoparticle+sensing+platforms.">Fluorescent core-shell Ag@SiO2 nanocomposites for metal-enhanced fluorescence and single nanoparticle sensing platforms.</a> J. Am. Chem. Soc. 129 (6), 1524-1525 (2007).</li><li>Lu, Y., Yin, Y., Li, Z. Y., Xia, Y. <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+self-assembly+of+Au@+SiO2+core-shell+colloids.">Synthesis and self-assembly of Au@ SiO2 core-shell colloids.</a> Nano. Lett. 2 (7), 785-788 (2002).</li><li>Link, S., Wang, Z. L., El-Sayed, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alloy+formation+of+gold-silver+nanoparticles+and+the+dependence+of+the+plasmon+absorption+on+their+composition.">Alloy formation of gold-silver nanoparticles and the dependence of the plasmon absorption on their composition.</a> J. Phys. Chem. B. 103 (18), 3529-3533 (1999).</li><li>He, 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=Rapid+Detection+of+Ricin+in+Milk+Using+Immunomagnetic+Separation+Combined+with+Surface+Enhanced+Raman+Spectroscopy.">Rapid Detection of Ricin in Milk Using Immunomagnetic Separation Combined with Surface Enhanced Raman Spectroscopy.</a> J. Food. Sci. 76 (5), N49-N53 (2011).</li><li>Zheng, J., He, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface-Enhanced+Raman+Spectroscopy+for+the+Chemical+Analysis+of+Food.">Surface-Enhanced Raman Spectroscopy for the Chemical Analysis of Food.</a> Compr. Rev. Food. Sci. F. 13 (3), 317-328 (2014).</li><li>He, L., Haynes, C. L., Diez-Gonzalez, F., Labuza, T. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+detection+of+a+foreign+protein+in+milk+using+IMS-SERS.">Rapid detection of a foreign protein in milk using IMS-SERS.</a> J. Raman. Spectrosc. 42 (6), 1428-1434 (2011).</li><li>Wei, W. Y., White, I. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+filter-based+approach+to+surface+enhanced+Raman+spectroscopy+for+trace+chemical+detection.">A simple filter-based approach to surface enhanced Raman spectroscopy for trace chemical detection.</a> Analyst. 137 (5), 1168-1173 (2012).</li><li>Cheng, M. L., Tsai, B. C., Yang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Silver+nanoparticle-treated+filter+paper+as+a+highly+sensitive+surface-enhanced+Raman+scattering+(SERS)+substrate+for+detection+of+tyrosine+in+aqueous+solution.">Silver nanoparticle-treated filter paper as a highly sensitive surface-enhanced Raman scattering (SERS) substrate for detection of tyrosine in aqueous solution.</a> Anal. Chim. Acta. 708 (1), 89-96 (2011).</li><li>Fierro-Mercado, P. M., Hern&#225;ndez-Rivera, S. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highly+sensitive+filter+paper+substrate+for+SERS+trace+explosives+detection.">Highly sensitive filter paper substrate for SERS trace explosives detection.</a> Int. J. Spectrosc. 2012, 716527 (2012).</li><li>Tran, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subnanogram+detection+of+dyes+on+filter+paper+by+surface-enhanced+Raman+scattering+spectrometry.">Subnanogram detection of dyes on filter paper by surface-enhanced Raman scattering spectrometry.</a> Anal. Chem. 56 (4), 824-826 (1984).</li><li>Wu, D., Fang, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+adsorption+behavior+of+p-hydroxybenzoic+acid+on+a+silver-coated+filter+paper+by+surface+enhanced+Raman+scattering.">The adsorption behavior of p-hydroxybenzoic acid on a silver-coated filter paper by surface enhanced Raman scattering.</a> J. Colloid Interface Sci. 265 (2), 234-238 (2003).</li><li>Wigginton, K. R., Vikesland, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gold-coated+polycarbonate+membrane+filter+for+pathogen+concentration+and+SERS-based+detection.">Gold-coated polycarbonate membrane filter for pathogen concentration and SERS-based detection.</a> Analyst. 135 (6), 1320-1326 (2010).</li><li>Berthod, A., Laserna, J. J., Winefordner, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+by+surface+enhanced+Raman+spectroscopy+on+silver+hydrosols+and+silver+coated+filter+papers.">Analysis by surface enhanced Raman spectroscopy on silver hydrosols and silver coated filter papers.</a> J Pharm Biomed Anal. 6 (6), 599-608 (1988).</li><li>Ackermann, K. R., Henkel, T., Popp, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+Online+Detection+of+Low-Concentrated+Drugs+via+a+SERS+Microfluidic+System.">Quantitative Online Detection of Low-Concentrated Drugs via a SERS Microfluidic System.</a> ChemPhysChem. 8 (18), 2665-2670 (2007).</li><li>Walter, A., M&#228;rz, A., Schumacher, W., R&#246;sch, P., Popp, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+a+fast,+high+specific+and+reliable+discrimination+of+bacteria+on+strain+level+by+means+of+SERS+in+a+microfluidic+device.">Towards a fast, high specific and reliable discrimination of bacteria on strain level by means of SERS in a microfluidic device.</a> Lab. Chip. 11 (6), 1013-1021 (2011).</li><li>Lee, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fast+and+sensitive+trace+analysis+of+malachite+green+using+a+surface-enhanced+Raman+microfluidic+sensor.">Fast and sensitive trace analysis of malachite green using a surface-enhanced Raman microfluidic sensor.</a> Anal. Chim. Acta. 590 (2), 139-144 (2007).</li><li>Guo, 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=Analysis+of+Silver+Nanoparticles+in+Antimicrobial+Products+Using+Surface-Enhanced+Raman+Spectroscopy+(SERS).">Analysis of Silver Nanoparticles in Antimicrobial Products Using Surface-Enhanced Raman Spectroscopy (SERS).</a> Environ. Sci. Technol. 49 (7), 4317-4324 (2015).</li><li>Narayanan, V. A., Begun, G. M., Stokes, D. L., Sutherland, W. S., Vo-Dinh, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Normal+Raman+and+surface+enhanced+Raman+scattering+(SERS)+spectra+of+some+fungicides+and+related+chemical+compounds.">Normal Raman and surface enhanced Raman scattering (SERS) spectra of some fungicides and related chemical compounds.</a> J. Raman. Spectrosc. 23 (5), 281-286 (1992).</li><li>Kang, J. S., Hwang, S. Y., Lee, C. J., Lee, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SERS+of+dithiocarbamate+pesticides+adsorbed+on+silver+surface;+thiram.">SERS of dithiocarbamate pesticides adsorbed on silver surface; thiram.</a> Bull. Korean. Chem. Soc. 23 (11), 1604-1610 (2002).</li><li>Li, Y. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+and+sensitive+in-situ+detection+of+polar+antibiotics+in+water+using+a+disposable+Ag-graphene+sensor+based+on+electrophoretic+preconcentration+and+surface-enhanced+Raman+spectroscopy.">Rapid and sensitive in-situ detection of polar antibiotics in water using a disposable Ag-graphene sensor based on electrophoretic preconcentration and surface-enhanced Raman spectroscopy.</a> Biosens. Bioelectron. 43, 94-100 (2013).</li><li>Clarke, S. J., Littleford, R. E., Smith, W. E., Goodacre, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+monitoring+of+antibiotics+using+Raman+and+surface+enhanced+Raman+spectroscopy.">Rapid monitoring of antibiotics using Raman and surface enhanced Raman spectroscopy.</a> Analyst. 130 (7), 1019-1026 (2005).</li><li>Zheng, J., Pang, S., Labuza, T. P., He, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Semi-quantification+of+surface-enhanced+Raman+scattering+using+a+handheld+Raman+spectrometer:+a+feasibility+study.">Semi-quantification of surface-enhanced Raman scattering using a handheld Raman spectrometer: a feasibility study.</a> Analyst. 138 (23), 7075-7078 (2013).</li><li>Zheng, J., Pang, S., Labuza, T. P., He, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+surface-enhanced+Raman+scattering+detection+using+a+handheld+and+a+bench-top+Raman+spectrometer:+A+comparative+study.">Evaluation of surface-enhanced Raman scattering detection using a handheld and a bench-top Raman spectrometer: A comparative study.</a> Talanta. 129, 79-85 (2014).</li></ol>

The authors have nothing to disclose.

Uno dei passaggi critici in questo protocollo è la sintesi Ag NP, dove uniformi Ag NP sono la chiave per ottenere risultati coerenti. Il tempo di riscaldamento e le concentrazioni di precursori devono essere controllati con precisione. La dimensione media di questa preparazione AGNPS è di 80 nm, che è stata misurata dal Zetasizer (dati non mostrati). Un altro passo importante è l&#39;aggregazione di sale in cui la concentrazione di sale e tempo di aggregazione devono essere controllati con precisione. Inoltre, la sc...

Surface Enhanced spettroscopia Raman (SERS) è una tecnica che combina spettroscopia Raman con la nanotecnologia. L&#39;intensità di scattering Raman di analiti a nobili metallici nano-superfici è notevolmente migliorata dalla risonanza plasmonica di superficie localizzata. 1 nanoparticelle di argento (Ag NP) sono di gran lunga i SERS più utilizzati substrati grazie alla sua elevata capacità di valorizzazione. 2 Fino ad oggi , sono stati sviluppati diversi metodi di sintesi di Ag NP. 3-6 Ag NP può essere usato da solo come substrati SERS efficaci, o combinati con altri materiali e strutture per migliorare la sensibilità e / o la funzionalità. 7-11 Tecniche SERS hanno dimostrato grande capacità di rilevamento di vari contaminanti quantità in tracce negli alimenti e nei campioni ambientali 12 Tradizionalmente, ci sono due modi comuni per la preparazione di un campione SERS:.. Soluzione-based e metodi di substrato a base 13 Il metho soluzione basata sud utilizza colloidi NP per mescolare con i campioni. Poi il complesso NP-analita viene raccolto mediante centrifugazione, e depositato su un supporto solido per la misurazione Raman dopo l&#39;essiccazione. Il metodo substrato a base di solito è applicata depositando diversi microlitri di campione liquido sul substrato solido prefabbricato. 14 Tuttavia, nessuno di questi due metodi sono efficaci e applicabili per una grande quantità di volume di campione. Diverse modifiche dei dosaggi SERS superato i limiti di volume, come l&#39;integrazione di un sistema di filtri 15-21 o l&#39;incorporazione di un dispositivo microfluidico. 21-24 I saggi SERS modificati hanno mostrato grande miglioramento nella sensibilità e la fattibilità del monitoraggio dei contaminanti chimici in grandi campioni di acqua. Qui mostriamo il protocollo dettagliato di fabbricazione e applicazione di un metodo basato SERS filtro siringa per rilevare quantità traccia di ferbam pesticidi e antibiotici ampicillina.

<table border="0" cellpadding="0" cellspacing="0" width="604">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">Ampicillin</td>
			<td style="width:128px;">Fisher Scientific</td>
			<td style="width:136px;">BP1760-5</td>
			<td style="width:131px;">N/A</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">Ferbam</td>
			<td style="width:128px;">Chem Service</td>
			<td style="width:136px;">N-11970-250MG</td>
			<td style="width:131px;">98+%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">Silver nitrate</td>
			<td style="width:128px;">Sigma Aldrich</td>
			<td style="width:136px;">209139</td>
			<td style="width:131px;">99.0+%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:211px;">Sodium citrate dehydrate</td>
			<td style="width:128px;">Sigma Aldrich</td>
			<td style="width:136px;">W302600</td>
			<td style="width:131px;">99+%</td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:211px;">Sodium chloride</td>
			<td style="width:128px;">Sigma Aldrich</td>
			<td style="width:136px;">S7653</td>
			<td style="width:131px;">99.5+%</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:211px;">EMD Millipore Durapore PVDF Membrane Filters</td>
			<td style="width:128px;">Fisher Scientific</td>
			<td style="width:136px;">VVLP01300</td>
			<td style="width:131px;">0.10 &#181;m Pore Size, hydrophilic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">Polycarbonate Filter Holders</td>
			<td style="width:128px;">Cole-Parmer</td>
			<td style="width:136px;">EW-29550-40</td>
			<td style="width:131px;">13 mm diameter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Analog Vortex Mixer</td>
			<td style="width:128px;">Fisher Scientific</td>
			<td>02-215-365</td>
			<td>N/A</td>
		</tr>
		<tr height="50">
			<td height="50" style="height:51px;width:211px;">Nutating Mixers</td>
			<td style="width:128px;">Fisher Scientific</td>
			<td>05-450-213</td>
			<td style="width:131px;">N/A</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:211px;">DXR Raman spectroscope</td>
			<td style="width:128px;">Thermo Scientific</td>
			<td style="width:136px;">IQLAADGABFFAHCMAPB</td>
			<td style="width:131px;">Laser power: 1 mW Exposure time: 5 s</td>
		</tr>
	</tbody>
</table>

a filter-based surface enhanced raman spectroscopic assay for rapid detection of chemical contaminants

We demonstrate a method to fabricate highly sensitive surface-enhanced Raman spectroscopic (SERS) substrates using a filter syringe system that can be applied to the detection of various chemical contaminants. Silver nanoparticles (Ag NPs) are synthesized via reduction of silver nitrate by sodium citrate. Then the NPs are aggregated by sodium chloride to form nanoclusters that could be trapped in the pores of the filter membrane. A syringe is connected to the filter holder, with a filter membrane inside. By loading the nanoclusters into the syringe and passing through the membrane, the liquid goes through the membrane but not the nanoclusters, forming a SERS-active membrane. When testing the analyte, the liquid sample is loaded into the syringe and flowed through the Ag NPs coated membrane. The analyte binds and concentrates on the Ag NPs coated membrane. Then the membrane is detached from the filter holder, air dried and measured by a Raman instrument. Here we present the study of the volume effect of Ag NPs and sample on the detection sensitivity as well as the detection of 10 ppb ferbam and 1 ppm ampicillin using the developed assay.

Le fasi principali di questo esperimento sono stati mostrati nel diagramma schematico (Figura 1). La Figura 2 ha dimostrato l&#39;importanza di usare il volume ottimizzata AGNPS nel rivestimento della membrana al fine di ottenere sensibilità massimizzato. 1 ml di Ag NP fornisce il segnale più forte quando si utilizza ferbam, rispetto a 0,5 ml (rivestimento insufficiente) o 2 ml (troppo rivestimento). <p class="jove_content" fo:keep...

Watch this Scientific Journal Video about A Filter-based Surface Enhanced Raman Spectroscopic Assay for Rapid Detection of Chemical Contaminants at JoVE.com

A Filter-based Surface Enhanced Raman Spectroscopic Assay for Rapid Detection of Chemical Contaminants

Procedimento per la fabbricazione ed eseguendo la superficie filtro Enhanced Raman spettroscopiche (SERS) Test per l&#39;individuazione dei contaminanti chimici (cioè, ferbam pesticidi e ampicillina) è presentata.

Una Superficie-filtro basato avanzata Raman spettroscopica Assay per Rapid individuazione dei contaminanti chimici

We demonstrate a method to fabricate highly sensitive surface-enhanced Raman spectroscopic (SERS) substrates using a filter syringe system that can be ...

a-filter-based-surface-enhanced-raman-spectroscopic-assay-for-rapid

Universidad San Sebastian

Research

JoVE Journal

Chemistry

9.3K Views.  University of Massachusetts Amherst.  Procedimento per la fabbricazione ed eseguendo la superficie filtro Enhanced Raman spettroscopiche (SERS) Test per l'individuazione dei contaminanti chimici (cioè, ferbam pesticidi e ampicillina) è presentata. 

Video: A Filter-based Surface Enhanced Raman Spectroscopic Assay for Rapid Detection of Chemical Contaminants

Preparation of Hydrophobic Metal-Organic Frameworks via Plasma Enhanced Chemical Vapor Deposition of Perfluoroalkanes for the Removal of Ammonia

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high surface area microporous materials, such as metal-organic frameworks (MOFs), unique challenges present themselves for PECVD treatments. Herein the protocol for development of a MOF that was previously unstable to humid conditions is presented. The protocol describes the synthesis of Cu-BTC (also known as HKUST-1), the treatment of Cu-BTC with PECVD of perfluoroalkanes, the aging of materials under humid conditions, and the subsequent ammonia microbreakthrough experiments on milligram quantities of microporous materials. Cu-BTC has an extremely high surface area (~1,800 m2/g) when compared to most materials or surfaces that have been previously treated by PECVD methods. Parameters such as chamber pressure and treatment time are extremely important to ensure the perfluoroalkane plasma penetrates to and reacts with the inner MOF surfaces. Furthermore, the protocol for ammonia microbreakthrough experiments set forth here can be utilized for a variety of test gases and microporous materials.

Herein the procedures for plasma enhanced chemical vapor deposition of perfluoroalkanes on microporous materials such as metal-organic frameworks to enhance their stability and hydrophobicity are described. Furthermore, breakthrough testing of milligram quantities of samples is described in detail.

Preparazione del idrofobi Frameworks Metal-Organic tramite Plasma avanzata Chemical Vapor Deposition del perfluoroalcani per la rimozione di ammoniaca

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high ...

Ricerca

Chimica

A Simple and Rapid Protocol for Measuring Neutral Lipids in Algal Cells Using Fluorescence

Algae are considered excellent candidates for renewable fuel sources due to their natural lipid storage capabilities. Robust monitoring of algal fermentation processes and screening for new oil-rich strains requires a fast and reliable protocol for determination of intracellular lipid content. Current practices rely largely on gravimetric methods to determine oil content, techniques developed decades ago that are time consuming and require large sample volumes. In this paper, Nile Red, a fluorescent dye that has been used to identify the presence of lipid bodies in numerous types of organisms, is incorporated into a simple, fast, and reliable protocol for measuring the neutral lipid content of Auxenochlorella protothecoides, a green alga. The method uses ethanol, a relatively mild solvent, to permeabilize the cell membrane before staining and a 96 well micro-plate to increase sample capacity during fluorescence intensity measurements. It has been designed with the specific application of monitoring bioprocess performance. Previously dried samples or live samples from a growing culture can be used in the assay.

A simple protocol to determine the neutral lipid content of algal cells using a Nile Red staining procedure is described. This time-saving technique offers an alternative to traditional gravimetric-based lipid quantification protocols. It has been designed for the specific application of monitoring bioprocess performance.

Una semplice e rapida il protocollo per la misurazione lipidi neutri in cellule algali Uso fluorescenza

Algae are considered excellent candidates for renewable fuel sources due to their natural lipid storage capabilities. Robust monitoring of algal ...

Preparation of Highly Porous Coordination Polymer Coatings on Macroporous Polymer Monoliths for Enhanced Enrichment of Phosphopeptides

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous polymer monoliths. The developed approach is based on the preparation of a macroporous polymer containing carboxylic acid functional groups and the subsequent step-by-step solution-based controlled growth of a layer of a porous coordination polymer on the surface of the pores of the polymer monolith. The prepared metal-organic polymer hybrid has a high specific micropore surface area. The amount of iron(III) sites is enhanced through metal-organic coordination on the surface of the pores of the functional polymer support. The increase of metal sites is related to the number of iterations of the coating process.
The developed preparation scheme is easily adapted to a capillary column format. The functional porous polymer is prepared as a self-contained single-block porous monolith within the capillary, yielding a flow-through separation device with excellent flow permeability and modest back-pressure. The metal-organic polymer hybrid column showed excellent performance for the enrichment of phosphopeptides from digested proteins and their subsequent detection using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presented experimental protocol is highly versatile, and can be easily implemented to different organic polymer supports and coatings with a plethora of porous coordination polymers and metal-organic frameworks for multiple purification and/or separation applications.

A procedure for the preparation of porous hybrid separation media composed of a macroporous polymer monolith internally coated by a high surface area microporous coordination polymer is presented.

Preparazione di altamente poroso Coordinamento rivestimenti polimerici su macroporosi Polymer Monoliti di avanzata Arricchimento fosfopeptidi

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous ...

A Method to Manipulate Surface Tension of a Liquid Metal via Surface Oxidation and Reduction

Controlling interfacial tension is an effective method for manipulating the shape, position, and flow of fluids at sub-millimeter length scales, where interfacial tension is a dominant force. A variety of methods exist for controlling the interfacial tension of aqueous and organic liquids on this scale; however, these techniques have limited utility for liquid metals due to their large interfacial tension.
Liquid metals can form soft, stretchable, and shape-reconfigurable components in electronic and electromagnetic devices. Although it is possible to manipulate these fluids via mechanical methods (e.g., pumping), electrical methods are easier to miniaturize, control, and implement. However, most electrical techniques have their own constraints: electrowetting-on-dielectric requires large (kV) potentials for modest actuation, electrocapillarity can affect relatively small changes in the interfacial tension, and continuous electrowetting is limited to plugs of the liquid metal in capillaries.
Here, we present a method for actuating gallium and gallium-based liquid metal alloys via an electrochemical surface reaction. Controlling the electrochemical potential on the surface of the liquid metal in electrolyte rapidly and reversibly changes the interfacial tension by over two orders of magnitude ( &#820;500 mN/m to near zero). Furthermore, this method requires only a very modest potential (&#60; 1 V) applied relative to a counter electrode. The resulting change in tension is due primarily to the electrochemical deposition of a surface oxide layer, which acts as a surfactant; removal of the oxide increases the interfacial tension, and vice versa. This technique can be applied in a wide variety of electrolytes and is independent of the substrate on which it rests.

We present a method to control the interfacial energy of a liquid metal in an electrolyte via electrochemical deposition (or removal) of a surface oxide layer. This simple method can control the capillary behavior of gallium-based liquid metals by tuning the interfacial energy rapidly, significantly, and reversibly using modest voltages.

Un metodo per manipolare Tensione superficiale di un metallo liquido tramite ossidazione superficiale e riduzione

Controlling interfacial tension is an effective method for manipulating the shape, position, and flow of fluids at sub-millimeter length scales, where ...

Preparation of Biopolymer Aerogels Using Green Solvents

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers (gelatin, agar, cellulose), only recently have biomasses been recognized as an abundant source of chemically diverse macromolecules for functional aerogel materials. Biopolymer aerogels (pectin, alginate, chitosan, cellulose, etc.) exhibit both specific inheritable functions of starting biopolymers and distinctive features of aerogels (80-99% porosity and specific surface up to 800 m2/g). This synergy of properties makes biopolymer aerogels promising candidates for a wide gamut of applications such as thermal insulation, tissue engineering and regenerative medicine, drug delivery systems, functional foods, catalysts, adsorbents and sensors. This work demonstrates the use of pressurized carbon dioxide (5 MPa) for the ionic cross linking of amidated pectin into hydrogels. Initially a biopolymer/salt dispersion is prepared in water. Under pressurized CO2 conditions, the pH of the biopolymer solution is lowered to 3 which releases the crosslinking cations from the salt to bind with the biopolymer yielding hydrogels. Solvent exchange to ethanol and further supercritical CO2 drying (10 - 12 MPa) yield aerogels. Obtained aerogels are ultra-porous with low density (as low as 0.02 g/cm3), high specific surface area (350 - 500 m2/g) and pore volume (3 - 7 cm3/g for pore sizes less than 150 nm).

A new way for the production of biopolymer-based aerogels by carbon dioxide (CO2) induced gelation is shown. The technique utilizes pressurized carbon dioxide (5 MPa) for the production of biopolymer hydrogels and supercritical CO2 (12 MPa) to convert gels into aerogels. The only solvents needed besides CO2 are water and ethanol.

Preparazione del biopolimero Aerogels che utilizzano solventi verdi

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers ...

A Novel Technique for Raman Analysis of Highly Radioactive Samples Using Any Standard Micro-Raman Spectrometer

A novel approach for the Raman measurement of nuclear materials is reported in this paper. It consists of the enclosure of the radioactive sample in a tight capsule that isolates the material from the atmosphere. The capsule can optionally be filled with a chosen gas pressurized up to 20 bars. The micro-Raman measurement is performed through an optical-grade quartz window. This technique permits accurate Raman measurements with no need for the spectrometer to be enclosed in an alpha-tight containment. It therefore allows the use of all options of the Raman spectrometer, like multi-wavelength laser excitation, different polarizations, and single or triple spectrometer modes. Some examples of measurements are shown and discussed. First, some spectral features of a highly radioactive americium oxide sample (AmO2) are presented. Then, we report the Raman spectra of neptunium oxide (NpO2) samples, the interpretation of which is greatly improved by employing three different excitation wavelengths, 17O doping, and a triple mode configuration to measure the anti-stokes Raman lines. This last feature also allows the estimation of the sample surface temperature. Finally, data that were measured on a sample from Chernobyl lava, where phases are identified by Raman mapping, are shown.

We present a technique for Raman spectroscopic analysis of highly radioactive samples compatible with any standard micro-Raman spectrometer, without any radioactive contamination of the instrument. We also show some applications using actinide compounds and irradiated fuel materials.

Una tecnica innovativa per l&#39;analisi Raman di campioni altamente radioattivo Uso di qualsiasi standard Micro-Raman Spectrometer

A novel approach for the Raman measurement of nuclear materials is reported in this paper. It consists of the enclosure of the radioactive sample in a ...

Observation and Analysis of Blinking Surface-enhanced Raman Scattering

From a single molecule at a silver nanoaggregate junction, blinking surface-enhanced Raman scattering (SERS) is observed. Here, a protocol is presented on how to prepare the SERS-active silver nanoaggregate, record a video of certain blinking spots in the microscopic image, and analyze the blinking statistics. In this analysis, a power law reproduces the probability distributions for bright events relative to their duration. The probability distributions for dark events are fitted by a power law with an exponential function. The parameters of the power law represent molecular behavior in both bright and dark states. The random walk model and the speed of the molecule across the entire silver surface can be estimated. It is difficult to estimate even when using averages, autocorrelation functions, and super-resolution SERS imaging. In the future, power law analyses should be combined with spectral imaging, because the origins of blinking cannot be confirmed by this analysis method alone.

This protocol describes the analysis of blinking surface-enhanced Raman scattering due to the random walk of a single molecule on a silver surface using power laws.

Osservazione e analisi del lampeggiante superficie-enhanced Raman Scattering

From a single molecule at a silver nanoaggregate junction, blinking surface-enhanced Raman scattering (SERS) is observed. Here, a protocol is presented on ...

Color Spot Test As a Presumptive Tool for the Rapid Detection of Synthetic Cathinones

Synthetic cathinones are a large class of new psychoactive substances (NPS) that are increasingly prevalent in drug seizures made by law enforcement and other border protection agencies globally. Color testing is a presumptive identification technique indicating the presence or absence of a particular drug class using rapid and uncomplicated chemical methods. Owing to their relatively recent emergence, a color test for the specific identification of synthetic cathinones is not currently available. In this study, we introduce a protocol for the presumptive identification of synthetic cathinones, employing three aqueous reagent solutions: copper(II) nitrate, 2,9-dimethyl-1,10-phenanthroline (neocuproine) and sodium acetate. Small pin-head sized amounts (approximately 0.1-0.2 mg) of the suspected drugs are added to the wells of a porcelain spot plate, and each reagent is then added dropwise sequentially before heating on a hotplate. A color change from very light blue to yellow-orange after 10 min indicates the likely presence of synthetic cathinones. The highly stable and specific test reagent has the potential for use in the presumptive screening of unknown samples for synthetic cathinones in a forensic laboratory. However, the nuisance of an added heating step for the color change result limits the test to laboratory application and decreases the likelihood of an easy translation to field testing.

Here we present a simple, inexpensive, and selective chemical spot test protocol for the detection of synthetic cathinones, a class of new psychoactive substances. The protocol is suitable for use in various areas of law enforcement that encounter illicit material.

Colore Spot Test come strumento presuntivo per la rilevazione rapida di Cathinones sintetico

Synthetic cathinones are a large class of new psychoactive substances (NPS) that are increasingly prevalent in drug seizures made by law enforcement and ...

Gold Nanoparticle Modified Carbon Fiber Microelectrodes for Enhanced Neurochemical Detection

For over 30 years, carbon-fiber microelectrodes (CFMEs) have been the standard for neurotransmitter detection. Generally, carbon fibers are aspirated into glass capillaries, pulled to a fine taper, and then sealed using an epoxy to create electrode materials that are used for fast scan cyclic voltammetry testing. The use of bare CFMEs has several limitations, though. First and foremost, the carbon fiber contains mostly basal plane carbon, which has a relatively low surface area and yields lower sensitivities than other nanomaterials. Furthermore, the graphitic carbon is limited by its temporal resolution, and its relatively low conductivity. Lastly, neurochemicals and macromolecules have been known to foul at the surface of carbon electrodes where they form non-conductive polymers that block further neurotransmitter adsorption. For this study, we modify CFMEs with gold nanoparticles to enhance neurochemical testing with fast scan cyclic voltammetry. Au3+ was electrodeposited or dipcoated from a colloidal solution onto the surface of CFMEs. Since gold is a stable and relatively inert metal, it is an ideal electrode material for analytical measurements of neurochemicals. Gold nanoparticle modified (AuNP-CFMEs) had a stability to dopamine response for over 4 h. Moreover, AuNP-CFMEs exhibit an increased sensitivity (higher peak oxidative current of the cyclic voltammograms) and faster electron transfer kinetics (lower &#916;EP or peak separation) than bare unmodified CFMEs. The development of AuNP-CFMEs provides the creation of novel electrochemical sensors for detecting fast changes in dopamine concentration and other neurochemicals at lower limits of detection. This work has vast applications for the enhancement of neurochemical measurements. The generation of gold nanoparticle modified CFMEs will be vitally important for the development of novel electrode sensors to detect neurotransmitters in vivo in rodent and other models to study neurochemical effects of drug abuse, depression, stroke, ischemia, and other behavioral and disease states.

In this study, we modify carbon-fiber microelectrodes with gold nanoparticles to enhance the sensitivity of neurotransmitter detection.

Microelettrodi in fibra di carbonio modificati con nanoparticle d'oro per una migliore rilevazione neurochimica

For over 30 years, carbon-fiber microelectrodes (CFMEs) have been the standard for neurotransmitter detection. Generally, carbon fibers are aspirated into ...

A Two-Step Pyrolysis-Gas Chromatography Method with Mass Spectrometric Detection for Identification of Tattoo Ink Ingredients and Counterfeit Products

Tattoo inks are complex mixtures of ingredients. Each of them possesses different chemical properties which have to be addressed upon chemical analysis. In this method for two-step pyrolysis online coupled to gas chromatography mass spectrometry (py-GC-MS) volatile compounds are analyzed during a first desorption run. In the second run, the same dried sample is pyrolyzed for analysis of non-volatile compounds such as pigments and polymers. These can be identified by their specific decomposition patterns. Additionally, this method can be used to differentiate original from counterfeit inks. Easy screening methods for data evaluation using the average mass spectra and self-made pyrolysis libraries are applied to speed up substance identification. Using specialized evaluation software for pyrolysis GS-MS data, a fast and reliable comparison of the full chromatogram can be achieved. Since GC-MS is used as separation technique, the method is limited to volatile substances upon desorption and after pyrolysis of the sample. The method can be applied for quick substance screening in market control surveys since it requires no sample preparation steps.

This method for two-step pyrolysis online coupled to gas chromatography with mass spectrometric detection and data evaluation protocol can be used for multi-component analysis of tattoo inks and discrimination of counterfeit products.

Un metodo di cromatografia a gas pirolisi a due fasi con rilevamento spettrometrico di massa per l'identificazione di ingredienti di inchiostro del tatuaggio e prodotti contraffatti

Tattoo inks are complex mixtures of ingredients. Each of them possesses different chemical properties which have to be addressed upon chemical analysis. ...