Optimizing the Composition of the Substrate Enhances the Performance of Peroxidase-like Nanozymes in Colorimetric Assays: A Case Study of Prussian Blue and 3,3'-Diaminobenzidine.

One of the emerging trends in modern analytical and bioanalytical chemistry involves the substitution of enzyme labels (such as horseradish peroxidase) with nanozymes (nanoparticles possessing enzyme-like catalytic activity). Since enzymes and nanozymes typically operate through different catalytic mechanisms, it is expected that optimal reaction conditions will also differ. The optimization of substrates for nanozymes usually focuses on determining the ideal pH and temperature.

Vertical Flow Immunoassay Based on Carbon Black Nanoparticles for the Detection of IgG against SARS-CoV-2 Spike Protein in Human Serum: Proof-of-Concept.

Point-of-care tests play an important role in serological diagnostics of infectious diseases and post-vaccination immunity monitoring, including in COVID-19. Currently, lateral flow tests dominate in this area and show good analytical performance. However, studies to improve the effectiveness of such tests remain important.

Prussian Blue Nanozymes with Enhanced Catalytic Activity: Size Tuning and Application in ELISA-like Immunoassay.

Prussian blue nanozymes possessing peroxidase-like activity gather significant attention as alternatives to natural enzymes in therapy, biosensing, and environmental remediation. Recently, Prussian blue nanoparticles with enhanced catalytic activity prepared by reduction of FeCl/K[Fe(CN)] mixture have been reported. These nanoparticles were denoted as 'artificial peroxidase' nanozymes.

Measuring the concentration of protein nanoparticles synthesized by desolvation method: Comparison of Bradford assay, BCA assay, hydrolysis/UV spectroscopy and gravimetric analysis.

The desolvation technique is one of the most popular methods for preparing protein nanoparticles for medicine, biotechnology, and food applications. We fabricated 11 batches of BSA nanoparticles and 2 batches of gelatin nanoparticles by desolvation method. BSA nanoparticles from 2 batches were cross-linked by heating at +70 °C for 2 h; other nanoparticles were stabilized by glutaraldehyde.

Nuclear magnetic resonance immunoassay of tetanus antibodies based on the displacement of magnetic nanoparticles.

A nuclear magnetic resonance (NMR) immunoassay based on the application of carbon-coated iron nanoparticles conjugated with recognition molecules was designed. The principle of the assay is that ELISA plates are coated with a capture element, and then an analyte is added and detected by conjugating the magnetic nanoparticles with recognition molecules. Afterwards, the elution solution (0.

Solid-phase nuclear magnetic resonance immunoassay for the prostate-specific antigen by using protein-coated magnetic nanoparticles.

A solid phase NMR-based sandwich immunoassay for the prostate-specific antigen (PSA) is presented. Carbon-encapsulated iron nanoparticles were functionalized with bovine serum albumin, coupled to monoclonal antibodies, and then used as magnetic labels. A nitrocellulose membrane with 8-μm pores was coated with capture antibodies and subsequently incubated with a serum sample and a suspension of the nanoconjugate.

Magnetic Nanoclusters Coated with Albumin, Casein, and Gelatin: Size Tuning, Relaxivity, Stability, Protein Corona, and Application in Nuclear Magnetic Resonance Immunoassay.

The surface functionalization of magnetic nanoparticles improves their physicochemical properties and applicability in biomedicine. Natural polymers, including proteins, are prospective coatings capable of increasing the stability, biocompatibility, and transverse relaxivity (r2) of magnetic nanoparticles. In this work, we functionalized the nanoclusters of carbon-coated iron nanoparticles with four proteins: bovine serum albumin, casein, and gelatins A and B, and we conducted a comprehensive comparative study of their properties essential to applications in biosensing.

Conjugation of carbon coated-iron nanoparticles with biomolecules for NMR-based assay.

In this work, we developed and optimized conjugates of carbon-coated iron nanoparticles (Fe@C) with streptavidin and monoclonal antibodies. The conjugation procedure included two stages. First, amino groups were grafted onto the carbon shell to facilitate noncovalent sorption of bovine serum albumin (BSA).

Highly Stable Conjugates of Carbon Nanoparticles with DNA Aptamers.

Conjugates of carbon nanoparticles and aptamers have great potential in many areas of biomedicine. In order to be implemented in practice, such conjugates should keep their properties throughout long storage period in commonly available conditions. In this work, we prepared conjugates of carbon nanoparticles (CNP) with DNA aptamers using streptavidin-biotin reaction.