Plasma-Induced Enhancement in Electronic Properties of Gold Nanoparticles: Application in Electrochemical Biosensing of Cortisol

Abstract

Homogeneous distribution of nanoparticle (NP) deposition on electrode surfaces and fine-tuning of their electronic properties is essential for controlling the active surface area, which significantly influences a sensor’s sensitivity. This work demonstrates the enhancements in the distribution and improvements in the electronic properties of gold nanoparticles (AuNPs) through a room-temperature plasma-assisted technique. The plasma-assisted deposition induced size reduction of AuNPs and improved the uniformity of particle distribution on the electrode surface. The homogeneity in the AuNP distribution was studied using scanning electron microscopy. The plasma-induced electronic effects of AuNPs were evaluated for electrochemical sensing using cortisol as a model analyte. Analytical features of the proposed AuNP-based cortisol sensor were investigated with the help of electrochemical techniques such as cyclic voltammetry and electrochemical impedance spectroscopy. For comparison, cortisol sensors without the plasma treatment were also fabricated, and it was found that the electronic properties of AuNPs tuned by plasma treatment helped increase the sensor sensitivity toward electrochemical detection of cortisol.

The Modernity of Ancient Pigments: A Historical Approach

“…More specifically, colloidal gold immunochromatography has been used to detect severe fever [152], gold nanoclusters have been found to be most suitable for targeted gastric cancer therapy [153] and gold nanocages show great promise as optical imaging contrast agents [154]. Colloidal gold can also play an important role in monitoring banned substances in foods [155] and biosensing applications [156].…”

“…More specifically, colloidal gold immunochromatography has been used to detect severe fever [152], gold nanoclusters have been found to be most suitable for targeted gastric cancer therapy [153] and gold nanocages show great promise as optical imaging contrast agents [154]. Colloidal gold can also play an important role in monitoring banned substances in foods [155] and biosensing applications [156]. Nanoparticulate gold also displays extraordinary catalytic properties with respect to selectivity and oxidative activity due to gold-substrate, e.g., Au-O and Au-CO, bond strength variability with co-ordination number [157].…”

Nanomaterials for Cortisol Sensing

“…Sonawane and co-workers demonstrated the improved distribution and electronic properties of gold nanoparticles (AuNPs) using a plasma-assisted technique at room temperature [ 75 ] ( Figure 15 ). This sensor was used for the electrochemical detection of cortisol by exploiting the plasma-induced effects of AuNPs.…”

“… Steps in the fabrication of a cortisol immunosensor on untreated (drop-cast) and AuNP-modified plasma-treated electrodes (reproduced with permission from [ 75 ]. Copyright 2021 American Chemical Society).…”

A “Two‐Part” Resonance Circuit based Detachable Sweat Patch for Noninvasive Biochemical and Biophysical Sensing

“…[7][8][9][10][11][12] Consequently, the need for real-time capture and analysis of cortisol levels in freshly excreted sweat has motivated continued efforts in developing bio-integrated analytical tools, ideally, with the wireless sensing capability. Recent works report the demonstration of cortisol sensors in various forms, including those working based on electrochemical impedance spectroscopy (EIS), [13][14][15] differential pulse voltammetry (DPV), [16,17] cyclic voltammetry (CV), [18,19] chronoamperometry (CA), [7,20] field-effect/electrochemical transistors, [21][22][23][24][25] and colorimetry. [26,27] The remarkable success of the pioneering studies has paved the way for utilizing this concept toward stress monitoring and management in biomedical research and translational engineering.…”