There is great attention on the development of quick, easy, and sensitive detection techniques for cancer biomarkers. Surface-enhanced Raman spectroscopy (SERS) is a powerful analytical technique that has gained significant attention in the field of cancer research. SERS-based immunoassays are often utilized for the detection of biological structures and molecules in medicine. In the study, a SERS-based immunosensor is developed for the detection of cancer protein biomarkers in serum on a flexible diatomite-based SERS active platform. The flexible SERS active platform is prepared on a regular box tape by coating nanoporous biosilica (diatomite) with AgNPs using the layer-by-layer assembly method. The platform is then modified with antibodies specific to target cancer proteins, such as human epidermal growth factor receptor2 (HER2), mucin4 (MUC 4), and prostate-specific antigen (PSA). The antibody-modified surface is incubated with the cancer proteins spiked in serum at different concentrations, and SERS spectra are obtained after the incubation of Raman probes. The method's sensitivity is evaluated, and the capability to detect protein biomarkers down to 0.1 ng/mL is demonstrated.
Extracellular vesicles (EVs) carry molecular cargo that includes nucleic acids, lipids, proteins, and various other biomarkers. Raman and SERS spectroscopy are label-free spectroscopy techniques based on inelastic scattering of laser light interacting with molecular vibrations. In our study, we employed Raman and SERS spectroscopy for the detection of amyloid beta protein in the molecular cargo of small EVs and bulk chemical analysis of EVs. We observed considerable variation as a reflection of the biochemical content of EVs related to the Aβ peptide incorporated in EVs extracted from the AD cell culture model. Next, we developed a new CMOS-based sensing platform for trapping, imaging, and chemical characterization of EVs via SERS (CMOS TrICC) with the experimental enhancement factor 5.0 × 104. We employed this platform for parallel trapping and sensitive biochemical analysis of the 100 nm nanospheres and EVs.
Surface-enhanced Raman Scattering (SERS) is an emerging analytical technique used for characterization of biological and non-biological structures. Plasmonic properties of nanostructures are main factors influencing SERS performance. Thus, fabrication of plasmonic nanostructures having different plasmonic properties is a significant research interest. Recently, guided-mode resonances (GMRs) in diatoms have significant attention due to their potential contribution to SERS enhancement. Furthermore, there is also evidence showing that diatoms can be utilized in improving SERS enhancement by optically coupling the GMRs of the diatom frustules with the LSPRs of the nanostructures. In this study, inexpensive, robust, and flexible diatom-based SERS platforms having different number of layers on a box tape are fabricated using layer-by-layer assembly of silver nanoparticles (AgNPs). The fabricated SERS platforms are characterized using UV-Vis spectroscopy and scanning electron microscopy (SEM). The SERS performance of the platforms was evaluated using 4 aminothiophenol (4-ATP) and rhodamine-6G. The results demonstrate that SERS performance of the platforms is dependent on the number of layers of the structures. The SERS platform having highest SERS activity can be used for the characterization of any molecules of interest
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