Novel highly sensitive Cu-based SERS platforms for biosensing applications (original) (raw)
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The Analyst, 2012
The on time diagnostics of bacterial diseases is one of the essential steps in the foregoing treatment of such pathogens. Here we sought to present an easy to use and robust method for the discrimination between Gram-positive (Enterococcus faecalis and Streptococcus pyogenes) and Gram-negative (Acinetobacter baumannii and Klebsiella pneumoniae) bacterial genera based on surface enhanced Raman scattering (SERS) spectroscopy. The robustness of our approach lies in the novel method for the production of the SER substrate based on silver nanoparticles and their subsequent recrystallization in solutions containing high concentrations of chloride ions. The method presented here could be an interesting alternative both to commonly used histochemical approaches and commercial SERS substrates.
Detection of bacteria by surface-enhanced Raman spectroscopy
Analytical and Bioanalytical Chemistry, 2006
In recent years there has been a strong interest in the development of rapid detection techniques of biological species, especially pathogens that are involved in food poisoning, water contamination, and airborne diseases. Conventional detection methods are time consuming and usually involve overnight culture of bacteria in a suitable growth medium. In this study we used surface-enhanced Raman scattering (SERS) to develop a rapid method of identifying bacteria. Molecules in close contact to the nanometallic surfaces show a huge enhancement in their Raman signature. The enhancement can be as great as 10 8-10 14. We also explored the application of dry nanostructured surfaces to characterize biomolecules by softly landing them on plasma-etched silver surfaces. By such landings, biomolecular gas phase ions were allowed to chemically bind to the surface so that the Raman effect was significantly enhanced and fluorescence was suppressed.
Applied Spectroscopy, 2004
Treatment of bacteria with silver yields intense and highly speci c surface-enhanced Raman spectroscopy (SERS) spectra from various cellular chemical components located in the vicinity of the silver colloids. In particular, we demonstrate an extreme sensitivity to avin components associated with the cell envelope and to their state of oxidation. Different spectra, possibly associated with DNA, carboxylates, and perhaps phosphates, are obtained from the soluble interior fraction of the cell.
Fabrication of surface enhanced Raman spectroscopy substrates on solid supports
Applied Surface Science, 2019
SERS-active screen-printed electrodes (SPEs) are extensively applied for electrochemical SERS biosensors with the advantages of portable, inexpensive cost, fast measurement, and sensitive detection. In our work, a useful fabrication method of sputtering deposition for SERSactive SPEs was proposed. Two kinds of working electrodes of SPE which were carbon electrode and gold electrode were successfully deposited by silver nanoparticles. Besides, the sputtering experiments of different substrates (paper, glass epoxy and polyethylene terephthalate) of the SPE were also conducted. The comparison of SERS enhancement of rhodamine 6G (R6G) on different kinds of SERS-active SPEs was introduced. In addition, the relationship between the surface roughness and SERS enhancement has been investigated. The enhancement factor (EF) of Ag/carbon and Ag/gold electrode were estimated as 2.8 3 10 5 and 2.2 3 10 7 , respectively. From the SERS experiments, the lower background noise of SERS signals could be observed through sputtering deposition method compared with the citrate reduction method. Furthermore, spectro-electrochemical analysis of uric acid was studied. The SERS signals were strongly increased upon the modulation of the applied voltage. These results demonstrated the applicability of this mass producible fabrication method for producing SERS-active SPEs, as well as, highlighting the future potential of commercial bioapplications.
Rapid bacterial diagnostics via surface enhanced Raman microscopy
Spectroscopy (Springfield, Or.), 2012
There is a continuing need to develop new techniques for the rapid and specific identification of bacterial pathogens in human body fluids especially given the increasing prevalence of drug resistant strains. Efforts to develop a surface enhanced Raman spectroscopy (SERS) based approach, which encompasses sample preparation, SERS substrates, portable Raman microscopy instrumentation and novel identification software, are described. The progress made in each of these areas in our laboratory is summarized and illustrated by a spiked infectious sample for urinary tract infection (UTI) diagnostics. SERS bacterial spectra exhibit both enhanced sensitivity and specificity allowing the development of an easy to use, portable, optical platform for pathogen detection and identification. SERS of bacterial cells is shown to offer not only reproducible molecular spectroscopic signatures for analytical applications in clinical diagnostics, but also is a new tool for studying biochemical activity...
Applied Microbiology and Biotechnology, 2011
Development of rapid and sensitive methods to detect pathogens is important to food and water safety. This study aimed to detect and discriminate important food-and waterborne bacteria (i.e., Escherichia coli O157:H7, Staphylococcus epidermidis, Listeria monocytogenes, and Enterococcus faecelis) by surface-enhanced Raman spectroscopy (SERS) coupled with intracellular nanosilver as SERS substrates. An in vivo molecular probing using intracellular nanosilver for the preparation of bacterial samples was established and assessed. Satisfactory SERS performance and characteristic SERS spectra were obtained from different bacterial samples. Distinctive differences were observed in SERS spectral data, specifically in the Raman shift region of 500-1,800 cm −1 , and between bacterial samples at the species and strain levels. The detection limit of SERS coupled with in vivo molecular probing using silver nanosubstrates could reach the level of single cells. Experiments with a mixture of E. coli O157:H7 and S. epidermidis for SERS measurement demonstrate that SERS could be used for classification of mixed bacterial samples. Transmission electron microscopy was used to characterize changes of morphology and cellular composition of bacterial cells after treatment of intracellular nanosilver. The results indicate that SERS coupled with intracellular silver nanosubstrates is a promising method for detection and characterization of food-and waterborne pathogenic and non-pathogenic bacterial samples.
Differentiation of bacterial strains by means of surface enhanced FT-Raman spectroscopy
Lithuanian Journal of Physics, 2012
The silver nanoparticle colloid was used to obtain surface enhanced Raman spectra of Listeria monocytogenes, Salmonela enterica, and Esherichia coli bacteria. The SERS spectra were captured using for excitation the near-infrared (1064 nm) laser radiation with reduced intensity, which ensured the prevention of the fluorescence background as well as photo-and thermal decomposition of the samples. It was found that the optimal size of silver nanoparticles for the enhancement of the Raman signal in the near-infrared spectral region is ca. 50 nm. The spectral data obtained in this study indicate that relative intensities of SERS spectral bands of bacteria can be used for spectral differentiation of bacteria. In case of Listeria, Salmonela, and Esherichia cells, the intensity ratio of spectral bands of adenine and cysteine can be used as a spectral marker for differentiation of the bacteria.
Surface enhanced Raman spectroscopy (SERS) for in vitro diagnostic testing at the point of care
Point-of-care (POC) device development is a growing field that aims to develop low-cost, rapid, sensitive in-vitro diagnostic testing platforms that are portable, selfcontained, and can be used anywhere -from modern clinics to remote and low resource areas. In this review, surface enhanced Raman spectroscopy (SERS) is discussed as a solution to facilitating the translation of bioanalytical sensing to the POC. The potential for SERS to meet the widely accepted "ASSURED" (Affordable, Sensitive, Specific, Userfriendly, Rapid, Equipment-free, and Deliverable) criterion provided by the World Health Organization is discussed based on recent advances in SERS in vitro assay development. As SERS provides attractive characteristics for multiplexed sensing at low concentration limits with a high degree of specificity, it holds great promise for enhancing current efforts in rapid diagnostic testing. In outlining the progression of SERS techniques over the past years combined with recent developments in smart nanomaterials, high-throughput microfluidics, and low-cost paper diagnostics, an extensive number of new possibilities show potential for translating SERS biosensors to the POC.
Applied Spectroscopy, 2011
The characterization, detection, and identification of bacteria using surface-enhanced Raman scattering (SERS) spectroscopy is drawing considerable attention due to its ability to provide rich intrinsic molecular information about molecules and molecular structures in close proximity to noble metal surfaces. However, sample preparation methods and experimental conditions must be carefully evaluated in order to obtain healthy, interpretable, and comparable results. In this study, several bacterial species including E. coli, B. megaterium, S. aureus, and S. cohnii were systematically evaluated to demonstrate the source of the spectral features of bacterial SERS spectra. It was found that the features observed in bacterial SERS spectra originate mostly from the bacteria surface with some contributions from metabolic activity or molecular species detached from the bacteria surface during sample preparation.