Laccases are multi-
copper oxidase enzymes having widespread applications in various biotechnological fields. However, low stability of free
enzymes restricts their industrial use. Development of effective methods to preserve and even increase the enzymatic activity is critical to maximize their use, though this remains a challenge. In the present study we immobilized Trametes versicolor
laccase on pH-responsive (and charge-switchable)
Pluronic-stabilized
silver nanoparticles (AgNPsTrp). Our results demonstrate that colloidal stabilization of AgNPsTrp with the amphiphilic copolymer
Pluronic F127 enhances
enzyme activity (AgNPsTrpF1 + Lac6) by changing the active site microenvironment, which is confirmed by circular dichroism (CD) and fluorescence spectroscopy. Detailed kinetic and thermodynamic studies reveal a facile strategy to improve the
protein quality by lowering the activation energy and expanding the temperature window for substrate hydrolysis. The immobilized nanocomposite did not show any change in flow behavior which indirectly suggests that the enzyme stability is maintained, and the
enzyme did not aggregate or unfold upon immobilization. Finally, assessing the anticancer efficacy of this nanocomposite in
breast cancer MCF-7 cells shows the inhibition of cell proliferation through β-
estradiol degradation and cells apoptosis. To understand the molecular mechanism involved in this process, semi qRT-PCR experiments were performed, which indicated significant decrease in the
mRNA levels of anti-apoptotic genes, for example, BCL-2 and NF-kβ, and increase in the
mRNA level of pro-apoptotic genes like p53 in treated cells, compared to control. Overall, this study offers a completely new strategy for tailoring nano-bio-interfaces with improved activity and stability of
laccase.