Electrodeposition of Silver Amalgam on Thin Gold Film Electrodes for Voltammetric Detection of 4‐Nitrophenol and DNA Labeled with Osmium Tetroxide‐Bipyridine Complex

Abstract

Alternative electrode materials suitable to prepare novel working electrode applicable in detecting biopolymers such as nucleic acids, proteins or glycoproteins, represent a significant contribution to bio‐electroanalysis. Herein, electrodes made of vapor‐deposited thin gold films (vAuE) were used as an alternative substrate for the electrodeposition of silver amalgam particles (AgAPs), next to indium tin oxide and pyrolytic graphite, which are already used. The conditions and parameters of double pulse chronoamperometry were optimized for the most‐sensitive voltammetric detection of 4‐nitrophenol (4‐NP). The resulting electrodes were characterized by scanning electron microscope with energy dispersive X‐ray spectroscopy. While 4‐NP could not be detected by bare nonactivated vAuEs at all, their electrochemical activation offered a limit of detection (LoD) of 25 and 5 μmol.l−1 by means of CV and DPV, respectively. AgAP electrodeposited on vAuE, offered 2.5‐times lower LoDs 10 μmol.l−1 by CV and comparable LoD 5 μmol.l−1 by DPV. Advantageously, AgAPs could be repeatedly deposited on and anodically dissolved from the vAuE with a relative standard deviation 13 % of the ten‐times repeated DPV signal of 4‐NP (100 μmol.l−1). In comparison to vAuE, the vAuE‐AgAP offered about 400 mV broader potential window, which allowed detection of single strand DNA fragment labeled by osmium tetroxide−bipyridine complex down to 2 ng.μl−1 by means of DPV.

Electrodeposition of Silver Amalgam Particles on Screen-Printed Silver Electrodes in Voltammetric Detection of 4-Nitrophenol and Artificial Nucleosides dTPT3 and d5SICS

“…Solution of 0.01 mol.l −1 Hg(NO3)2 in 0.1 mol.l −1 KNO3 was prepared according to procedure described in Ref. [2] . The 0.001 mol.l −1 stock solution of 4-NP (p.a., >99%, Sigma-Aldrich) was prepared in deionized water.…”

“…In analogy with results obtained for preparation of silver amalgam particles on ITO [1] and gold [2] and pyrolytic graphite electrodes [3] , DPCA was selected as suitable method for electrodeposition of AgAP on SPAgE. During the optimization of the electrodepositions, various Ag/Hg ratio in solution and different parameters of chronoamperometry (pulse (E1) and grow (E2) potentials and times (t2)) were used.…”

“…Electrodeposition of silver amalgam particles (AgAPs) on various substrates was found to be perspective approach for development of novel (spectro-)electroanalytical systems applicable in detection of electrochemically reducible compounds, nucleic acids or proteins [1][2][3][4] . Moreover, AgAPs were confirmed as a suitable material for introduction of plasmonic functionalities into photochemical and spectro-electrochemical systems [5] .…”

“…Surface modification of scree-printing electrodes by electrodeposited AgAPs has never been studied before according to our best of knowledge. Since AgAPs have proven to be suitable for the surface modification of transparent indium-tin oxide (ITO) [1] , vapor deposited golden thin film (vAuE) [2] or pyrolytic graphite (PG) [3] , herein in-house fabricated screen-printed silver electrode with silver composite working electrode (SPAgE) has been selected as novel substrate for AgAPs deposition. This metal silver based substrate should also minimize risk of mercury contamination, thank to high mercury affinity to the silver substrate, and thus increased mechanical stability and about two orders of magnitude lowered mercury vapor pressure [7] .…”

“…This metal silver based substrate should also minimize risk of mercury contamination, thank to high mercury affinity to the silver substrate, and thus increased mechanical stability and about two orders of magnitude lowered mercury vapor pressure [7] . For all the above mention substrates, the AgAPs modification has significantly facilitated electroreduction of organic nitro compounds [1] and additionally allowed detection of labeled [2] or even unlabeled nucleic acids [3] or proteins [4] . Analogical effects are expected in case of AgAPs electrodeposition on SPAgE, but detail study and optimization are needed.…”