ARTICLE | doi:10.20944/preprints201912.0022.v1
Subject: Physical Sciences, Optics Keywords: direct laser processing; femtosecond laser pulses; superhydrophobic textures; analyte enrichment; plasmonic nanostructures; SERS; medical drugs
Online: 3 December 2019 (11:19:55 CET)
We report an easy-to-implement device for SERS-based detection of various analytes dissolved in water droplets at trace concentrations. The device combines an analyte-enrichment system and SERS-active sensor site, both produced via inexpensive and high-performance direct fs-laser printing. Fabricated on a surface of water-repellent polytetrafluoroethylene substrate as an arrangement of micropillars, the analyte-enrichment system supports evaporating water droplet in the Cassie-Baxter superhydrophobic state, thus ensuring delivery of the dissolved analyte molecules towards the hydrophilic SERS-active site. The efficient pre-concentration of the analyte onto the sensor site based on densely-arranged spiky plasmonic nanotextures results in its subsequent label-free identification by means of SERS spectroscopy. Using the proposed device, we demonstrate reliable SERS-based fingerprinting of various analytes, including common organic dyes and medical drugs at ppb concentrations. The proposed device is believed to find applications in various areas, including label-free environmental monitoring, medical diagnostics, and forensics.
REVIEW | doi:10.20944/preprints202007.0459.v1
Subject: Chemistry, Electrochemistry Keywords: current-potential curve; multi-enzymatic cascades; multi-analyte detection; mass-transfer-controlled amperometric response; potentiometric coulometry
Online: 20 July 2020 (08:16:47 CEST)
Bioelectrocatalysis provides the intrinsic catalytic-functions of redox enzymes to non-specific electrode reactions and is the most important and basic concept for biosensors. This review starts by describing fundamental characteristics of bioelectrocatalytic reactions in mediated and direct electron transfer types from a theoretical viewpoint and summarizes amperometric biosensors based on multi-enzymatic cascades and for multi-analyte detection. The review also introduces prospective aspects of two new concepts of biosensors: mass-transfer-controlled (pseudo)steady-state amperometry at microelectrodes with enhanced enzymatic activity without calibration curves and potentiometric coulometry at enzyme/mediator-immobilized biosensors for absolute determination.