Modification of Ag nanoparticles with mixed thiols for improved SERS detection of poorly adsorbing target molecules: detection of MDMA

Stewart, Alfred Walter; Bell, Steven E. J.

doi:10.1039/c0cc05312k

Cited by 36 publications

(32 citation statements)

References 11 publications

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“…The chemical functionality of ligand molecules determines most of the nanoparticles' interface-related properties7. Mixtures of ligand molecules are often used to coat the nanoparticles89. Typically, this is done so that each of the ligand shell components provides a different property to the nanoparticles.…”

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confidence: 99%

Determination of monolayer-protected gold nanoparticle ligand–shell morphology using NMR

et al. 2012

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It is accepted that the ligand shell morphology of nanoparticles coated with a monolayer of molecules can be partly responsible for important properties such as cell membrane penetration and wetting. When binary mixtures of molecules coat a nanoparticle, they can arrange randomly or separate into domains, for example, forming Janus, patchy or striped particles. To date, there is no straightforward method for the determination of such structures. Here we show that a combination of one-dimensional and two-dimensional NMR can be used to determine the ligand shell structure of a series of particles covered with aliphatic and aromatic ligands of varying composition. This approach is a powerful way to determine the ligand shell structure of patchy particles; it has the limitation of needing a whole series of compositions and ligands' combinations with NMR peaks well separated and whose shifts due to the surrounding environment can be large enough.

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confidence: 99%

Determination of monolayer-protected gold nanoparticle ligand–shell morphology using NMR

et al. 2012

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“…All of the particles used in this study provide strong enhancement of the surface species’ Raman signals, which allows the SAM composition to be monitored in situ using surface-enhanced Raman spectroscopy (SERS), since each compound gives its own characteristic Raman spectrum. 4,36 …”

mentioning

confidence: 99%

Controlling Assembly of Mixed Thiol Monolayers on Silver Nanoparticles to Tune Their Surface Properties

Stewart

Zheng²,

McCourt³

et al. 2012

ACS Nano

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106

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Modifying the surfaces of metal nanoparticles with self-assembled monolayers of functionalized thiols provides a simple and direct method to alter their surface properties. Mixed self-assembled monolayers can extend this approach since, in principle, the surfaces can be tuned by altering the proportion of each modifier that is adsorbed. However, this works best if the composition and microstructure of the monolayers can be controlled. Here, we have modified preprepared silver colloids with binary mixtures of thiols at varying concentrations and modifier ratios. Surface-enhanced Raman spectroscopy was then used to determine the effect of altering these parameters on the composition of the resulting mixed monolayers. The data could be explained using a new model based on a modified competitive Langmuir approach. It was found that the composition of the mixed monolayer only reflected the ratio of modifiers in the feedstock when the total amount of modifier was sufficient for approximately one monolayer coverage. At higher modifier concentrations the thermodynamically favored modifier dominated, but working at near monolayer concentrations allowed the surface composition to be controlled by changing the ratios of modifiers. Finally, a positively charged porphyrin probe molecule was used to investigate the microstructure of the mixed monolayers, i.e., homogeneous versus domains. In this case the modifier domains were found to be <2 nm.

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“…31 A method to enhance the SERS detection of MDMA by modifying the surface of metal colloids with self-assembled monolayers (SAM's) composed of x-functionalized alkyl or aryl thiols was reported. 32 Best results were observed for colloids modified with mixed SAM's of sodium mercaptopropanesulfonate (MPS) and benzyl mercaptan (BZM) in the ratio of 6:4. Mixed x-functionalized thiols promote the adsorption of MDMA to silver colloids and thus improve detection limits (<50 ppm).…”

Section: Basic Principles and Instrumentationmentioning

confidence: 91%

“…Method improves the detection of poorly adsorbing target molecules on metal colloids as well as reduces the signals from interfering species present in sample. 32 Surface enhanced Raman spectroscopic method for the identification of trace amounts of morphine, codeine and hydrocodone in their base form was discussed. 33 785 and 633 nm lasers with a power of 100 mW and 20 mW at sample were used to record the spectra from 2 ll of drug solution.…”

Section: Basic Principles and Instrumentationmentioning

confidence: 99%

Raman spectroscopy – Basic principle, instrumentation and selected applications for the characterization of drugs of abuse

Bumbrah

Sharma

2016

Egyptian Journal of Forensic Sciences

184

107

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This review gives an overview of the developments in the analysis of drugs of abuse and other illicit substances by Raman spectroscopy for forensic purpose. The review covers the brief overview of basic principle and instrumentation of Raman spectroscopy along with selected and recent applications for characterization of drugs of abuse using this technique. These applications show the potential value of Raman spectroscopy in the qualitative and quantitative analysis of trace amounts of drugs of abuse and other illicit substances on different matrices such as cloth, currency notes, fiber etc., without extensive sample preparation in a non-destructive manner. ª 2015 Hosting by Elsevier B.V. on behalf of The International Association of Law and Forensic Sciences (IALFS).

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Modification of Ag nanoparticles with mixed thiols for improved SERS detection of poorly adsorbing target molecules: detection of MDMA

Cited by 36 publications

References 11 publications

Determination of monolayer-protected gold nanoparticle ligand–shell morphology using NMR

Determination of monolayer-protected gold nanoparticle ligand–shell morphology using NMR

Controlling Assembly of Mixed Thiol Monolayers on Silver Nanoparticles to Tune Their Surface Properties

Raman spectroscopy – Basic principle, instrumentation and selected applications for the characterization of drugs of abuse

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