Entrapment of enzyme in the presence of proline: effective approach to enhance activity and stability of horseradish peroxidase

Development of a robust enzyme cascade system: co-immobilization of laccase and versatile peroxidase on polyacrylamide hydrogel for enhanced BPA degradation

Biodegradation using a synergically integrated system of laccase (E.C. 1.10.3.2) and versatile peroxidase (EC 1.11.1.16) co-immobilized on the polyacrylamide (PAM) hydrogel presents a promising solution for removing endocrine disrupting chemicals (EDCs) like bisphenol A (BPA) from wastewater. In this study, we developed a tailored biocatalyst consisting of a fungal laccase from Pleurotus ostreatus IBL-02 and versatile peroxidase, enzyme cascade co-immobilized covalently on a 7% (w/v) PAM hydrogel, offering high catalytic potential across various pH and temperature ranges. The PAM-VP/Lac structure was analyzed using scanning electron microscopy and Fourier-transform infrared spectrophotometry, revealing improved characteristics compared to free counterparts (FLac and FVP). The optimal pH for FLac, FVP, Lac/VP, and PAM-VP/Lac was 4, 5, 6, and 7, respectively. PAM-VP/Lac exhibited optimal activity at 50-60 °C, higher than FLac, FVP, and Lac-VP. PAM-VP/Lac showed superior operational stability, retaining 99.2% of its activity after eight cycles, with an immobilization efficiency of 78.62 ± 1.15% and activity recovery of 33.71 ± 0.2%. It also demonstrated enhanced thermal stability, with a two-fold increase in half-life at 50-70 °C. Thermodynamic analysis showed significant improvements in stability parameters for PAM-VP/Lac. This system achieved complete BPA degradation within two and a half hr, highlighting its potential for industrial-scale environmental remediation.

Alleviation of chromium stress in plants using metal and metal oxide nanoparticles

Chromium (Cr), one of the hazardous pollutants, exists predominantly as Cr(VI) and Cr(III) in the environment. Cr(VI) is more toxic than Cr(III) due to its high mobility and solubility. Elevated levels of Cr in agricultural soil due to various anthropogenic activities cause Cr accumulation in plants, resulting in a significant reduction in plant yield and quality due to Cr-induced physiological, biochemical and molecular alterations. It can infiltrate the food chain through crop plants and cause harmful effects in humans via biomagnification. Cr(VI) is linked to cancer in humans. Therefore, mitigation strategies are required to remediate Cr-polluted soils and limit its accumulation in plants for safe food production. Recent research on metal and metal oxide nanoparticles (NPs) has shown that they can effectively reduce Cr accumulation and phytotoxicity. The effects of these NPs are influenced by their type and dose, exposure method, plant species and experimental settings. In this review, we present an up-to-date compilation and comprehensive analysis of the existing literature regarding the process of uptake and distribution of Cr and impact and potential mechanisms of metal and metal oxide nanoparticles led mitigation of Cr-induced stress in plants. We have also discussed recent developments, existing research gaps and future research directions in the field of Cr stress mitigation by NPs in plants. Overall, this review can provide valuable insights in reducing Cr accumulation and toxicity using metal and metal oxide nanoparticles, thereby promoting safe and sustainable cultivation of food and phytostabilization of Cr-polluted soil.

Enhancing the peroxidase-mimicking activity of hemin by covalent immobilization in polymer nanogels

A polymeric nanozyme that can closely mimic peroxidase is presented. The coordination between pendant hemins and primary amines together with the synergistic interactions between substrates and nanogels contribute to the enhanced catalytic activity.