Catalase-conjugated collagen surfaces and their application for the quantification determination of H2O2 in milk

Construction of pyrimidine derivatives-copper enzyme mimics as colorimetric sensing elements for efficient detection of phenolic compounds and hydrogen peroxide

As concerns about environmental pollution grow, the rapid identification and quantification of pollutants have become increasingly vital. In this work, a series of pyrimidine derivatives-Cu enzyme mimics (Cytosine-Cu, Cytidine-Cu, and CMP-Cu) with laccase- and peroxidase-like activity were prepared through the coordination of Cu2+ with different pyrimidine derivatives (PDs). The PDs-Cu enzyme mimics contain high levels of Cu+ and N - Cu coordination structures, which provide sufficient catalytic sites for the substrates. Compared with natural enzymes and other nanozymes, PDs-Cu demonstrate superior substrate affinity, catalytic efficiency, stability, and resistance to interference. It was found that PDs-Cu enzyme mimics have different catalytic activities towards different phenolic compounds. Therefore, a three-channel colorimetric sensor array (CSA) was successfully developed utilizing PDs-Cu as the sensing elements. The CSA can accurately identify different phenolic compounds and their mixtures in seawater and simulated wastewater. Additionally, a colorimetric method for detecting H2O2 in eye drops was developed, featuring a detection range of 0.1-10.0 μM and a limit of quantification of 0.1 μM. This research not only provides a flexible protocol for regulating the catalytic activity of enzyme mimics, but also provides important inspiration for the development of methods for rapid identification and detection of contaminants in the environmental water.

Biodegradation of environmental pollutants using catalase-based biocatalytic systems

The synergistic combination of biocatalysts and nanomaterials provides a new interface of a robust biocatalytic system that can effectively remediate environmental pollutants. Enzymes, such as catalase-based constructs, impart the desired candidature for catalytic transformation processes and are potential alternatives to replace conventional remediation strategies that have become laborious and somewhat inefficient. Furthermore, the controlled or uncontrolled discharge of various emerging pollutants (EPs) into water bodies is equally proportional to the fast-growing population and extensive urbanization. EPs affect the entire living being and continuously deteriorate the environmental system, directly or indirectly. The occurrence of EPs (even released after partial treatments, but still in bioactive forms) disturbs ecological integrity. Due to the ineffectiveness of in-practice traditional remediation processes, new and robust treatment measures as effective and sustainable remediation have become a meaningful goal. In this context, special attention has been shifted to engineering an enzyme (catalase)-based biodegradation system with immense prospects in environmental cleanup. The unique synergistic combination of nanomaterials (having multifunctional attributes) with enzymes of interest makes them a state-of-the-art interface that can further ameliorate bio-catalysis and biodegradation performance. This review covers current research and scientific advancement in developing and deploying catalase-based biocatalytic systems to mitigate several EPs from the environment matrices. The biocatalytic features of catalase, along with the mechanistic insight into H2O2 neutralization, several nano-based materials loaded with catalase, including nanoparticles (NPs), carbon nanotubes (CNTs), metal-organic frameworks (MOFs), polymeric-based composites, oxime-functionalized cryo-gel disks, electro-spun nanofibrous membranes, and other hybrid materials have also been discussed with suitable examples.

Biorecognition of hydrogen peroxide using a novel electrochemical platform designed with Glossoscolex paulistus giant hemoglobin

The giant extracellular hemoglobin of the annelid Glossoscolex paulistus (HbGp; 3.6 MDa) is a valuable and underexplored supramolecular hemoprotein system for the biorecognition of reactive oxygen species. In this work, an efficient and simple electrochemical platform was designed for analyzing H₂O₂, using HbGp covalently immobilized on Nafion®-modified glassy carbon electrode, named as HbGp/Nafion/GCE. Voltammetric and spectroscopic studies revealed the importance of prior modification of the electrodic support with the conducting polymer to obtain satisfactory hemoglobin electroactivity, as well as a biocompatible microenvironment for its immobilization. In terms of biological activity, it was observed a greater reactivity of the biomolecule in acidic medium, enabling the detection of the analyte by a quasi-reversible mechanism, whose kinetics was limited by analyte diffusion. In the presence of H₂O₂, the native structure of hemoglobin (oxy-HbGp (Fe²⁺)) oxidizes to ferryl-HbGp (Fe⁴⁺) and this redox reaction can be monitored on HbGp/Nafion/GCE with a detection limit of 8.5 × 10^‒7  mol L^-1. In addition to high sensitivity, the electrochemical biosensor also provided reproducible, consistent, and accurate measurements. The electroanalytical method showed an appropriate performance to quantify different levels of H₂O₂ in milk samples, proving the potential of HbGp/Nafion/GCE for this purpose.