A novel nanozyme assay utilising the catalytic activity of silver nanoparticles and SERRS

Abstract

aArtificial enzymes have become an increasingly interesting area of research due to their many advantages over natural protein enzymes which are expensive, difficult to isolate and unable to stand harsh environments. An important area of this research involves using metal nanoparticles as artificial enzymes, known as nanozymes, which exhibit peroxidase-like activity enabling them to catalyse the oxidation of substrates such as 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2), giving a colorimetric response. Here we exploit the catalytic activity of silver nanoparticles (Ag NPs) in a surface based silver-linked immunosorbent assay (SLISA) to detect human C-reactive protein (CRP), an inflammatory marker. Ag NPs were conjugated to antibodies with specific recognition for the corresponding target antigenic molecule, CRP, and the Ag NPs were used to catalyse the oxidation of TMB by H2O2. The resulting coloured oxidation product was detected using SERRS. We demonstrate that Ag NPs can replace the enzymes used in a conventional ELISA and a detection limit of 1.09 ng/mL of CRP can be achieved. It indicates the promise for SLISAs for biomarker detection and opens the way for further assays of this nature to be created. This novel assay has the potential to be optimised to detect lower levels of CRP and can be further extended for the sensitive and specific detection of other relevant biomarkers.

High‐Performance Biosensing Systems Based on Various Nanomaterials as Signal Transducers

“…The catalytic and enzymatic properties of NP‐based biosensing platforms have also been highlighted due to their rapid sensing process, visualization by the naked eye and high sensitivity . In particular, since MeNPs possess enzyme‐like activities, they can be utilized in the place of an enzyme in an enzyme‐linked immunosorbent assay (ELISA) to catalyze and activate the visualization reagent . Ahmed et al reported the detection of the influenza virus (H1N1) through the catalytic and enzymatic activity of a positive Au NPs ((+) Au NPs)‐based colorimetric immunoassay .…”

“…[52][53][54][55][56] In particular, since MeNPs possess enzyme-like activities, they can be utilized in the place of an enzyme in an enzyme-linked immunosorbent assay (ELISA) to catalyze and activate the visualization reagent. [57][58][59] Ahmed et al reported the detection of Figure 1. Target DNA sensing performance by plasmonic coupling interaction between Au NPs.…”

Visual monitoring and optical recognition of digoxin by functionalized AuNPs and triangular AgNPs as efficient optical nano‐probes

“…In this investigation, TMB (3,3 0 ,5,5 0 -tetramethylbenzidine) which is oxidized to a blue charge transfer complex (CTC) and H 2 O 2 as a substrate have been applied (Figure 4). 21 This then produces a measurable colorimetric signal which is symmetrical with the value of extant analytes. Subsequently, the concentration of the desired target has been measured by UV-Vis spectroscopy method.…”

Highly Sensitive Electrochemical Determination of Norepinephrine Using Poly Acrylic Acid‐Coated Nanoceria

“…[3] These advantages lead to applications such as colorimetric diagnosis, [4][5][6] electrochemical analysis, [7][8][9][10] and therapy. [11] The catalytic properties of nanozymes can be diversified by the morphology and surface of nanomaterials such as metal nanoparticles, [12,13] metal oxide nanostructures, [14][15][16] and carbon based materials. [17,18] Among these nanomaterials, cerium oxide nanoparticles (nanoceria) have recently received growing attention due to their free radical scavenging properties, which concern the coexistence of two oxidation states (Ce 3 + and Ce 4 + ) on their surface.…”