SERS-active nanocellulose substrate via in-situ photochemical synthesis

Surface-enhanced Raman scattering spectroscopy (SERS) is a highly-sensitive technology to detect trace target analytes. Herein, a series of flexible SERS substrate for the detection of malachite green (MG) bactericide were developed via in situ photochemical synthesis of silver nanoparticles (AgNPs) based on two dimentional (2D) nanocellulose film without additional reducing agent. For the first time, silver nanocubes (AgNCs) with sharp edges and corners, which are conductive to the formation of hot spots, were successfully prepared and uniformly loaded on the nanocellulose film by controlling the reaction conditions. The obtained composite SERS substrate showed high sensitivity to Rhodamine 6G (R6G) and MG with limit of detection (LOD) of 4.7 × 10^-12 and 1.2 × 10^-8 g/L, respectively. In addition, the relative standard deviation (RSD) was calculated lower than 15 %, demonstrating the good detection reproducibility. The nanocellulose-based 2D SERS substrate shows the potential as a detection platform in the rapid and sensitive identification of various toxic and harmful pollutants.

Hydrophilic modification of PVDF-based SERS imprinted membrane for the selective detection of L-tyrosine

The polyvinylidene difluoride (PVDF) membrane has received considerable attention as a flexible surface enhanced Raman scattering (SERS) substrate due to its excellent mechanical and physicochemical properties. However, the poor fouling resistance of PVDF membrane due to its intrinsic hydrophobic property limits its practical application. To address this, in this investigation, a SERS imprinted membrane is synthesized based on W₁₈O₄₉/Ag composites. Firstly, to promote hydrophilicity, N-vinyl-2-pyrrolidone (NVP) and triethoxyvinylsilane (VTES) are copolymerized by hydrolysis condensation and linked with engineered polyvinypyrrolidone (PVP) chains exposed on the surface of membrane. Furthermore, W₁₈O₄₉/Ag composites are dispersed on the membrane under the assistance of polydopamine (pDA) to promote the pollution resistance. Subsequently, in order to demonstrate the practical detection property, W₁₈O₄₉/Ag/PVDF membrane is selected as the SERS substrate to synthesize SERS imprinted membrane by precipitation polymerization for the selective detection of L-tyrosine. The characteristic results reveal that the SERS-imprinted membrane exhibits satisfactory hydrophilicity, and it can effectively degrade the pollutant molecules absorbed on its surface under ultraviolet light illumination. It is proved from the detection results that the LOD of WADP-MIMs for L-tyrosine reached 10^-9 mol L^-1 when the concentration of L-tyrosine changed between 10^-3-10^-9 mol L^-1. The correlation coefficient (R²) is 0.994 and the limit of detection is 10^-9 mol L^-1. Meanwhile, it can be applied for the selective detection of L-tyrosine in mixture samples. Overall, this study presents a novel approach for the hydrophilic modification and pollution resistance enhancement of PVDF-based SERS imprinted membrane, which can be effectively utilized for the selective detection of practical samples.

Probing blood plasma samples for the detection of diabetes using SERS aided by PCA and LDA multivariate data analyses

Fabrication of a SERS-active substrate using Langmuir–Blodgett and self-assembly techniques for the detection of diabetes from blood plasma samples.