SERS-Active Substrates Nanoengineering Based on e-Beam Evaporated Self-Assembled Silver Films

Abstract

Surface-enhanced Raman spectroscopy (SERS) has been intensely studied as a possible solution in the fields of analytical chemistry and biosensorics for decades. Substantial research has been devoted to engineering signal enhanced SERS-active substrates based on semi-continuous nanostructured silver and gold films, or agglomerates of micro- and nanoparticles in solution. Herein, we demonstrate the high-amplitude spectra of myoglobin precipitated out of ultra-low concentration solutions (below 10 μg/mL) using e-beam evaporated continuous self-assembled silver films. We observe up to 105 times Raman signal amplification with purposefully designed SERS-active substrates in comparison with the control samples. SERS-active substrates are obtained by electron beam evaporation of silver thin films with well controlled nanostructured surface morphology. The characteristic dimensions of the morphology elements vary in the range from several to tens of nanometers. Using optical confocal microscopy we demonstrate that proteins form a conformation on the surface of the self-assembled silver film, which results in an effective enhancement of giant Raman scattering signal. We investigate the various SERS substrates surface morphologies by means of atomic force microscopy (AFM) in combination with deep data analysis with Gwyddion software and a number of machine learning techniques. Based on these results, we identify the most significant film surface morphology patterns and evaporation recipe parameters to obtain the highest amplitude SERS spectra. Moreover, we demonstrate the possibility of automated selection of suitable morphological parameters to obtain the high-amplitude spectra. The developed AFM data auto-analysis procedures are used for smart optimization of SERS-active substrates nanoengineering processes.

Large Area Few-Layer Hexagonal Boron Nitride as a Raman Enhancement Material

“…For 1 μM MB dye, we also observed similar degree of enhancement to that of 1.5, 6, and 7 nm films synthesized by APCVD film. The surface morphology (roughness) usually plays an important role in creation of local hot spots, which leads to even higher enhancement of the Raman signal of the adsorbed analyte [ 42 , 43 ]. Interestingly, for the case of a highly wrinkled surface of 7 nm thick hBN film (with highest surface roughness), we observed similar enhancement of ≈10 4 for MB molecules compared to the flat hBN films.…”

Point-of-Use Rapid Detection of SARS-CoV-2: Nanotechnology-Enabled Solutions for the COVID-19 Pandemic

“…The SERS largely depends on the type of substrate and its preparation. SERS platform can be designed in the form of colloidal metal solutions as well as thin precipitated or nanometer films, and the most common types of SERS-active substrates showing the largest effects are colloidal silver and gold, and evaporated films of these metals [120][121][122]. In a similar study, Yeh et al showed that by using the synthesized Nowadays, the molecular and immunoassay methods are widely used to detect COVID-19 deploying virus RNA proteins; however, they are not useful for POC applications due to limitations, such as the need for expensive equipment and experienced personnel, as well as the high cost of diagnostic services.…”

“…The SERS largely depends on the type of substrate and its preparation. SERS platform can be designed in the form of colloidal metal solutions as well as thin precipitated or nanometer films, and the most common types of SERS-active substrates showing the largest effects are colloidal silver and gold, and evaporated films of these metals [ 120 , 121 , 122 ]. In a similar study, Yeh et al showed that by using the synthesized nitrogen modified carbon nanotubes decorated with Au NPs, virus detection would be very accurate in a short time.…”

Gliсated Human Albumin Registration Using Nanostructured Silver Substrates Films Realizing the Effect of Surface Enhanced Scattering

“…Такие пленки могут быть эффективно использованы для изучения и регистрации спектров ГКР биологических аналитов различных типов. Такие подложки были разработаны в [2].…”

“…Было впервые продемонстрировано разделение гликированного и негликированного альбумина на ГКР-активных субстратах на основе самоорганизующихся непрерывных серебряных пленок. Этот тип подложки был ранее предложен в работе [2]. Было показано, что морфология поверхности играет критическую роль в анализе белка, поскольку она обеспечивает достаточный уровень сигнала ГКР от раствора белков с низкой концентрацией.…”