Formulation of products based on copper and silver nano-particles and evaluation of their applications in biochemical

This study aimed to synthesize eco-friendly bio-based nanomaterials and evaluate their efficiency in enzyme immobilization and biomedical applications. Starch-copper (St-CuNPs), alginate-copper (Alg-CuNPs), starch-silver (St-AgNPs), and alginate-silver nanoparticles (Alg-AgNPs) were synthesized via a green approach and characterized using SEM, FTIR, and XRD analyses. Enzyme immobilization experiments were carried out using invertase from Saccharomyces cerevisiae and rennet extract. Optimization was performed by varying pH. temperature, immobilization time, and nanoparticle concentration. Response Surface Methodology (RSM) with Central Composite Design (CCD) was used for rennet immobilization. Antioxidant and anti-inflammatory activities of AgNPs were evaluated using FRAP, DPPH, protein denaturation, and hemolysis inhibition assays. Characterization confirmed the formation of crystalline nanoparticles stabilized by starch and alginate functional groups. CuNPs exhibited mixed metallic and oxide phases while AgNPs displayed pure face-centered cubic metallic phases. Optimal invertase immobilization occurred at 4 h, pH 9, 30 ʻC, and 3% St-CuNPs, while the optimization of enzyme activity revealed that the optimal conditions were 40 ʻC and pH 4.5 for the immobilized enzyme, and 35 ʻC and pH 5 for the free enzyme. Reusability tests showed that the immobilized enzyme retained about 49% of its initial activity after ten successive cycles. Rennet immobilization was optimal at pH 2.3, 24 ʻC, and 8% Alg-CuNPs, achieving a maximum coagulant activity of 6.5 RU/mLThe immobilized enzyme showed more stable thermal and pH performance than the free enzyme, retaining activity across 30-50 ʻC and pH 4-8, and exhibited slower activity loss during six weeks of storage. Antioxidant and anti-inflammatory assays showed that St-AgNPs had the highest FRAP and DPPH activity (IC30401 and 844.8 æg/mL), Alg-AgNPs exhibited stronger protein stabilization (IC30-131.7 æg/mL), and St-AgNPs had better membrane-stabilizing effects (ICs = 889.6 æg/mL). The results confirm that starch- and alginate-based nanomaterials effectively reduce and stabilize nanoparticles, making them suitable for enzyme immobilization. These green nanomaterials demonstrated excellent reusability, enhanced enzyme stability, and notable antioxidant and anti-inflammatory potential, highlighting their promising applications in biotechnology and biomedicine.