Fungal Biosystems for the Fabrication of Copper Nanoparticles: An Effective Approach for the Treatment of Bacterial Biofilms

Multidrug-resistant bacterial infections present a serious global public health threat. This threat is exacerbated by biofilm-forming bacteria that have greater intrinsic resistance to various classes of currently available antibiotics. This study reports the fabrication of copper nanoparticles (CuNPs) by using a cell-free lysate of Aspergillus niger (A. niger). A library of CuNPs was generated by varying different parameters including salt (CuSO₄) concentration, fungal lysate-to-salt ratio, pH, temperature, and exposure time and screened based on yield, size, and charge. The minimum inhibitory concentrations (MICs) of CuNPs were 4-fold lower for Gram-negative as compared to Gram-positive bacteria. CuNPs were able to effectively penetrate the dense structure of biofilms leading to the disruption of the bacterial cell membrane integrity as confirmed by confocal microscopy. CuNPs exhibited enhanced selectivity toward biofilms of Gram-negative bacteria, with low mammalian cell toxicity. CuNPs generated from A. niger lysate provided an effective option for the treatment of biofilm infections, addressing the critical need for combating drug-resistant bacteria.