Electrodeposition of silver amalgam particles on screen-printed silver electrodes in voltammetric detection of 4-nitrophenol, bovine serum albumin and artificial nucleosides dTPT3 and d5SICS

Electrodeposition of silver amalgam particles (AgAPs) on various substrates represents a prospective approach to the development of a novel detection system applicable in the study of various electrochemically active substances, including nucleic acids and proteins. Herein, a double pulse chronoamperometric deposition of AgAPs on in-house fabricated screen-printed silver electrodes (SPAgE) has been optimized using the voltammetric signal of a model electrochemically reducible organic nitro-compound, 4-nitrophenol (4-NP). The surface morphology of SPAgE-AgAP was monitored by scanning electron microscopy with an energy dispersive X-ray spectrometer. A compact three-electrode sensor consisting of the working (substrate) SPAgE, counter graphite, and pseudoreference Ag|AgCl electrodes was designed for analysis of electrochemically reducible compounds in a 96-well plate with about 150-mu l sample volume per well. Herein optimized SPAgE-AgAP allowed detection of 4-NP down to 1 mu mol l- 1 using cyclic voltammetry. Advantageously, differential pulse voltammetry at SPAgE-AgAP allowed highly sensitive detection of artificial nucleosides dTPT3 and d5SICS (developed to expand genetic alphabet in semi-synthetic organisms) using their catalytic hydrogen evolution signals, with limits of detection of 0.4 pmol l- 1. Moreover, these artificial nucleosides were easily detectable in the excess of natural nucleosides down to molar ratio 1:12000. Using constant current chronopotentiometric stripping and the catalytic peak H, we further demonstrated detection of a protein, bovine serum albumin, at the SPAgE-AgAP. Thus, we present the SPAgE-AgAP as a potent tool applicable in simple, fast, and sensitive electrochemical detection of reducible or catalytically active species, with prospective applications in hot research areas including chemical and synthetic biology.