PEGylated Gold Nanoparticles with Interesting Plasmonic Properties Synthesized Using an Original, Rapid, and Easy-to-Implement Procedure (original) (raw)
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The Analyst, 2013
The ability to easily prepare Surface Enhanced Raman Scattering (SERS) substrates by the assembly of chemically synthesized gold nano-colloids is of great interest for the advancement of SERS-based optical detection and identification of molecular species of biological or chemical interest, pollutants or warfare agents. In this work we employ three very simple strategies, which can be implemented in any laboratory without the need of specialized equipment, to prepare assemblies of citrate-stabilized spherical gold 10 colloids: (i) drop-coating, which induces the assembly of colloids in so-called coffee rings; (ii) a simplified variant of convective self-assembly (CSA), based on water evaporation in a constrained geometry, which yields highly uniform strips of nanoparticles (NP); (iii) assembly onto chemically functionalized glass surfaces which yields randomly assembled colloids and colloidal clusters. The SERS properties of the resulting colloidal assemblies are comparatively evaluated under multiple excitation 15 lines with p-aminothiophenol (pATP) as a model Raman scatterer. The NP strips obtained by CSA prove to be SERS-active both in the visible and NIR and posses a highly uniform SERS response as demonstrated by spectra at individually selected sites and by confocal SERS mapping. Further it is shown that these NP strips are effective for the detection of cytosine, a DNA component, and for multi-analyte SERS detection. These results, showing how an efficient SERS substrate can be obtained by a very 20 simple assembly method from easy-to-synthesize colloidal gold nanoparticles, can have an impact on the development of analytical SERS applications. 65 In this work we address the following question: what types of Au NP assemblies can be prepared by very simple methods, without using special equipment, to make SERS substrates of decent quality for SERS-based detection and analytical applications? Accordingly we propose three different assembly strategies, 70 65
Unique Gold Nanoparticle Aggregates as a Highly Active SERS Substrate
The Journal of Physical Chemistry, 2004
A unique gold nanoparticle aggregate (GNA) system has been shown to be an excellent substrate for surfaceenhanced Raman scattering (SERS) applications. Rhodamine 6G (R6G), a common molecule used for testing SERS activity on silver, but generally difficult to detect on gold substrates, has been found to readily bind to the GNA and exhibit strong SERS activity due to the unique surface chemistry afforded by sulfur species on the surface. This GNA system has yielded a large SERS enhancement of 10 7-10 9 in bulk solution for R6G, on par with or greater than any previously reported gold SERS substrate. SERS activity has also been successfully demonstrated for several biological molecules including adenine, L-cysteine, L-lysine, and L-histidine for the first time on a gold SERS substrate, showing the potential of this GNA as a convenient and powerful SERS substrate for biomolecular detection. In addition, the SERS spectrum of R6G on single aggregates has been measured. We have shown that the special surface properties of the GNA, in conjunction with strong near-IR absorption, make it useful for SERS analysis of a wide variety of molecules.
…, 2011
The detection of Raman signals inside living cells is a topic of great interest in the study of cell biology mechanisms and for diagnostic and therapeutic applications. This work presents the synthesis and characterization of flower-shaped gold nanoparticles and demonstrates their applicability as SERS-active tags for cellular spectral detection. The particles were synthesized by a facile, rapid new route that uses ascorbic acid as a reducing agent of gold salt. Two triarylmethane dyes which are widely used as biological stains, namely malachite green oxalate and basic fuchsin, were used as Raman-active molecules and the polymer mPEG-SH as capping material. The as-prepared SERS-active nanoparticles were tested on a human retinal pigment epithelial cell line and found to present a low level of cytotoxicity and high chemical stability together with SERS sensitivity down to picomolar particle concentrations.
Multimodal Gold Nanoprobes for SERS Bioimaging
Journal of Nanomedicine & Nanotechnology, 2015
Growing number of studies report on the improved sensitivity of various imaging modalities in detecting abnormalities within tumours. Surface enhanced Raman scattering (SERS) microscopy is a novel optical imaging technique which is advantageous in terms of greater multiplexing capability, minimal or no photobleaching of the Raman reporters, better spatial resolution and low signal-to-noise ratio within complex biological environment. For the enhancement of the Raman vibrational signal in SERS bioimaging, gold nanoparticles (GNP) are the most viable among metal nanoparticles because of comparable ease in controlling its size distribution and biocompatibility, among other parameters. GNP based SERS nanoprobes can be synthesised by tagging Raman reporter and conjugating with target specific biomolecules. Because of GNP's wide-ranging optical properties and narrow and distinct signal from SERS, other labelling methodologies like fluorescence microscopy, magnetic resonance imaging (MRI), etc. can also be implemented along with SERS bioimaging, by tagging fluorophores, magnetic nanoparticles, etc. This review focuses on various structures and shapes of GNP, fabricating GNP based nanoprobes and the multiplexing and multi-modality capability of GNP based SERS nanoprobes.
Composite blends of gold nanorods and poly(t-butylacrylate) beads as new substrates for SERS
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2013
New SERS substrates based on blends of Au NRs and PtBA beads.SERS monitoring of 2,2′-dithiodipyridine onto Au anisotropic nanostructures.Low cost process with potential for the up-scale fabrication of SERS substrates.Polymer based composites containing metal nanoparticles are shown to provide new substrates for SERS detection and simultaneously enable the development of new tools for molecular sensing. A very important aspect on the use of hybrid materials relates to the observation of synergistic effects that result from the use of distinct components such as a polymer and metal nanoparticles. We report here the preparation of new SERS substrates made from blends of colloidal Au (nanospheres and nanorods) and PtBA (poly(t-butylacrylate)). The observed SERS enhancement depends on the characteristics of the obtained hybrid material. When compared to the starting Au colloids, the Au/PtBA nanocomposites led to SERS spectra with more intense bands, using 2,2′-dithiodipyridine as molecular probe. The origin of the stronger Raman signal in this case, is possibly due to a combination of events related to the nanocomposite characteristics, including the formation of Au assemblies at the polymer surface due to particle clustering, and the absorption increase in a spectral region closer to the laser excitation wavelength. The strategy described here is a low-cost process with potential for the up-scale fabrication of SERS substrates, namely by using other types of nanocomposites.
Journal of Materials Science, 2015
Surface Enhanced Raman Scattering is a sensitive and widely used as spectroscopic technique for chemical and biological structure analysis. One of the keys to increase the sensitivity of SERS sensors is to use nanoparticles/nanostructures. Here, we report on the density effect of gold nanodisks on SERS intensity for a highly sensitive detection of chemical molecules. Various densities of gold nanodisks with a height of 30 nm on gold/glass substrate were fabricated by electron beam lithography in order to have a good uniformity and reproducibility. The evolution of the Enhancement Factor with nanodisk density was quantified and compared to numerical calculations. An enhancement factor as high as 2.6×10 7 was measured for the nanodisk with a diameter of 110 nm and a periodicity of 150 nm which corresponds to the biggest density (42.2%).
SERS Activities of Green Synthesized Silver Nanoparticles
Journal of Cluster Science, 2015
Spherical silver nanoparticles with average particle size of 11 nm having surface plasmon resonance peak at 440 nm are synthesized using fruit extract of Ananas comosus as reducing agent. The bright circular spots in the selected area electron diffraction pattern and the peaks corresponding to (111), (200), (220) and (311) planes in the X-ray diffraction pattern were evident for the crystallinity of face centered cubic structured nanoparticles. The surface-enhanced Raman scattering (SERS) activities of prepared silver nanoparticles were found to be size-dependent, the smaller nanoparticles showing higher SERS enhancement. The orientation of the pyridine molecule on the silver surface can be deduced from ring stretching vibrations, the ring breathing mode, in-plane and out-of-plane vibrations and the SERS surface selection rule. The SERS spectrum indicates that the pyridine adsorbed on the silver surface in a stand-on orientation via its nitrogen lone pair electrons. It is used to indicate the advantage of this green method of preparing silver based SERS colloids.
Application of Gold Nanoparticle to Plasmonic Biosensors
International journal of molecular sciences, 2018
Gold nanoparticles (GNPs) have been widely utilized to develop various biosensors for molecular diagnosis, as they can be easily functionalized and exhibit unique optical properties explained by plasmonic effects. These unique optical properties of GNPs allow the expression of an intense color under light that can be tuned by altering their size, shape, composition, and coupling with other plasmonic nanoparticles. Additionally, they can also enhance other optical signals, such as fluorescence and Raman scattering, making them suitable for biosensor development. In this review, we provide a detailed discussion of the currently developed biosensors based on the aforementioned unique optical features of GNPs. Mainly, we focus on four different plasmonic biosensing methods, including localized surface plasmon resonance (LSPR), surface-enhanced Raman spectroscopy (SERS), fluorescence enhancement, and quenching caused by plasmon and colorimetry changes based on the coupling of GNPs. We be...
Molecular Crystals and Liquid Crystals, 2020
In this study, gold nanoparticles (GNPs) were successfully fabricated via a polymer-templating method and applied for surface-enhanced Raman scattering (SERS) enhancement. The block copolymer, poly(ethylene glycol)-block-poly(styrene-alt-maleic anhydride) (PEG-b-PSM) modified with thiol groups, was used to prepare GNPs. The results indicated that the polymer facilitated GNPs to form an assembly without aggregation; thus, the distance between adjacent GNPs could be ideal for SERS application. Furthermore, when deposited onto indium tin oxide (ITO) thin film, GNPs prepared via the polymer-templating method showed more ordered behavior than GNPs prepared by using a conventional method, that is, citrate reduction.