Star‐Shaped Gold Nanoparticles as Friendly Interfaces for Protein Electrochemistry: the Case Study of Cytochrome c

Abstract

Gold nanostars with an average tip‐to‐tip length of 52±6 nm were functionalized with different capping agents and used as electrode modification materials for protein electrochemistry. Direct electron transfer between cytochrome c and nanostar‐coated pyrolytic graphite electrodes was observed with the protein in solution. The electrochemical response was improved at nanostars functionalized with a 1 : 1 mixture of 11‐mercaptoundecanoic acid and 4‐mercaptobenzoic acid in comparison with gold nanospheres coated with a similar functionalization. Further immobilization of cytochrome c on pyrolytic graphite while conjugated with the same nanostars guaranteed the maintenance of the protein's native properties, whereas direct adsorption on the bare or nanostar‐modified electrodes resulted in an altered conformational state. The pseudo‐peroxidase activity of the altered cytochrome c was enhanced in the presence of the nanostars.

Nanoparticles in Electrochemical Immunosensors – A Concept and Perspective

“…Meanwhile, NMs exposing hydrophobic surfaces promote stronger hydrophobic interactions, leading to additional intramolecular hydrogen bonding and protein transition to nonnative conformations, with increased or decreased biological activity. [167] Therefore, a combination of different NMs in producing nanocomposites represents an optimal solution for obtaining synergistic effects in Ab physical adsorption and immunosensing performance, mitigating the risk of extreme denaturation phenomena. Detection Ab labeled single-walled carbon nanohorns (SWCNHs)/thionine(thi)/AuNPs has been realized, working as electroactive tracers for the detection of carcinoembryonic antigen, [168] or polyvinylpyrrolidone-capped AgNPs/MWCNTs were conjugated with TIR2 Abs to determine aspartame in food samples.…”

“…This phenomenon is often the cause of protein denaturation. Meanwhile, NMs exposing hydrophobic surfaces promote stronger hydrophobic interactions, leading to additional intramolecular hydrogen bonding and protein transition to non‐native conformations, with increased or decreased biological activity [167] . Therefore, a combination of different NMs in producing nanocomposites represents an optimal solution for obtaining synergistic effects in Ab physical adsorption and immunosensing performance, mitigating the risk of extreme denaturation phenomena.…”

Reusable and highly sensitive SERS immunoassay utilizing gold nanostars and a cellulose hydrogel-based platform

“…To further assess the activity of the sandwich formation between SERS-immunotags, HRP and anti-HRP, the electrophoretic mobility of AuNSs, SERS-immunotags, SERSimmunotags with bound HRP and further bound to anti-HRP (a solution simulation of a positive sandwich assay) were measured by AGE 14,15,34,35 . Results on SI, Figure S7, are a proofof-principle for application of the SERS-immunotags to the SERS-based immunoassay.…”

Reduced graphene oxide/titanium carbide MXene nanocomposite‐modified electrode for electrochemical hemoglobin biosensor

“…[ 6 ] To address this issue, various chemically modified interfaces have been designed in order to improve the electron transfer process. [ 7–9 ]…”

“…[6] To address this issue, various chemically modified interfaces have been designed in order to improve the electron transfer process. [7][8][9] Recently, two-dimensional nanomaterials have been widely used to obtain electrochemical biosensors with improved performances. [10][11][12][13] In particular, graphenebased materials exhibit extremely large surface-to-volume ratio and high conductivity, which act as a bridge between the electroactive part of the redox protein and the electrode to strongly improve the rate of electron transfer at the sensing interface.…”