Immobilization of laccase on poly-L-lysine modified silver nanoparticles formed by green synthesis for enhanced stability, suppressed estrogenic activity of 17β-estradiol, biocompatibility and anti-cancer action: An in vitro and in silico study

Abstract

Laccases have wide applications in diverse biotechnological industries, including bioremediation of toxic environmental pollutants present in industrial effluents. However, their use is restricted due to their low operational stability and high production cost. Immobilization of laccase helps in overcoming these challenges. Here, we have immobilized laccase from Trametes versicolor on silver nanoparticles (AgNPs) synthesized using extracts of Syzigium aromaticum. Laccase was immobilized through electrostatic self-assembly strategy in the presence of poly-L-lysine (PLL) and displayed good activity [effectiveness factor (η) of 0.83]. It exhibited higher thermal and storage stability in comparison to its free counterpart. Moreover, it displayed good recyclability by retaining about 50% of its activity after 10 cycles of use. The immobilized enzyme successfully degraded 17β-estradiol which is an estrogenic environmental pollutant and a risk factor for breast cancer. Molecular docking revealed the involvement of hydrophobic interactions and hydrogen bonding in the formation of a stable laccase-17β-estradiol complex. Molecular dynamic (MD) simulation studies further validated the stability of this docked complex. AgNP-PLL-laccase exhibited dose dependent cytotoxicity towards MCF-7 cell lines. Insignificant hemolytic activity suggests the biocompatibility of these potential anti-cancerous nanoparticles. Hence, immobilization of laccase on the green synthesized AgNPs improves the enzyme’s stability, while simultaneously providing synergistic anticancer effects against MCF-7 cell lines.