Synthesis and Characterization of Antibody-Protected Bimetallic Nanoclusters with Catalytic Properties

Abstract

In this work a novel and facile method for the synthesis of gold-platinum bimetallic nanoclusters (NCs) embedded in the structure of an IgG (Au/Pt NCs-IgG) is presented. Proteins have been widely used as scaffolds for the synthesis of atomic clusters. The harsh conditions usually required during the synthesis imply the denaturation of different proteins and the loss of their biological activity. We propose a strategy for the synthesis of NCs employing IgG as a scaffold performed using physiological conditions in order to maintain unalterable the IgG structure allowing the resulting material bind to Protein G and the antigen. NCs composed of two different types of atoms exhibit higher catalytic activity than monometallic nanoclusters (NC), due to the synergistic effect of two diverse atoms. This peroxidase-like activity and the maintained affinity for its antigen make Au/Pt NCs-IgG a suitable material for its use as a detection antibody in a direct sandwich Enzyme-Linked Immuno Sorbent Assay (ELISA). Use of Au/Pt NCs-IgG as an alternative to IgG tethered to horseradish peroxidase in ELISA boosts the limit of detection (LOD) by 56 times.

Platinum Janus Nanoparticles as Peroxidase Mimics for Catalytic Immunosorbent Assay

“…As shown in Figure b, the Pt 4 f spectra of Pt Janus NPs show typical bands of 71 and 72.4 eV, respectively. This is attributed to the characteristic peaks of the Pt(111) crystals, confirming the existence of Pt(0) and Pt­(II), which is consistent with the XRD results. As shown in Figure c, the 2p 3/2 and 2p 1/2 peaks of Si are observed at 102.9 and 103.5 eV, corresponding to the electronic state of Si–O–Si …”

“…Nanozymes have attracted much attention because of their low cost, tolerance, high catalytic activity, and easy recovery. − Benefiting from these outstanding advantages, nanozymes have broad prospects in biosensing, biomimetic catalysis, and selective catalysis. − The reports show that carbon-based, iron-based, − copper-based, , precious metal-based, − and metal–organic framework nanozymes , have become highly valued. However, numerous single-component nanozymes tend to aggregate during the catalytic process.…”

Enzyme-mimic catalytic activities and biomedical applications of noble metal nanoclusters

“…For instance, Mora-Sanz et al have developed gold–platinum bimetallic NCs within the immunoglobulin G (IgG) structure (denoted as Au/Pt NCs-IgG hereafter). 84 The presence of two different types of metal atoms in these NCs leads to a synergistic effect, resulting in higher catalytic activity compared to the corresponding mono-metal NCs. However, it is worth noting that metal NC-based artificial enzymes generally exhibit poor pH tolerability, stimulating numerous studies aiming to structural and catalytic stability across a wide range of pH values.…”

An Emerging Nanozyme Class for à la carte Enzymatic‐Like Activities based on Protein‐Metal Nanocluster Hybrids

“…bimetallic NCs stabilized by antibodies, which lost their activity after only 10 days. [19] For the following experiments, we focused on the characterization of the top-performing catalytic nanozyme, Au 7 Pt 50 @C6 His , as a potential hybrid material that could overcome the robustness issues associated with HRP enzyme. As depicted in Figure 5B, the highest catalytic activity of the hybrid was attained at pH 7, with significant activity displayed at pH 6 and 8 (higher than 75% of the maximum activity is conserved).…”

“…[ 11,15,16 ] The selection of the appropriate template is key to modulate the final features of the mNCs and enable the implementation of the nanozymes in specific fields. Therefore, the use of engineered small ligands, [ 17 ] metal organic frameworks, [ 18 ] or biomacromolecules such as antibodies [ 19 ] permits the application of mNCs as bioimaging agents, photocatalysts, or sensing probes, respectively.…”