Silver Prussian Blue Analogue Nanoparticles: Rationally Designed Advanced Nanomedicine for Multifunctional Biomedical Applications

The development of simple, cost-effective, and advanced multifunctional technology is the need of the hour to combat cancer as well as bacterial infections. There have been reports of silver nanoparticles (AgNPs), silver salts, and Prussian blue (PB) being used for medicinal purposes which are clinically approved. In this context, in the present communication, we incorporated PB and silver salts (silver nitrate) to develop silver PB analogue nanoparticles (SPBANPs), a new nanomedicine formulation as a safer and effective mode of treatment strategy (2-in-1) for both cancer and bacterial infections. Considering all fundamental issues of nanomedicine, along with understanding of the biological impact of PB, we designed a simple, fast, efficient, cheap, and eco-friendly method for the synthesis of [poly(<i>N</i>-vinyl-2-pyrrolidone)]-stabilized silver hexacyanoferrate nanoparticles (silver PB analogue: Ag₃[Fe(CN)₆] abbreviated as SPBANPs). Various analytical tools were used to analyze and characterize the nanomaterials (SPBANPs). The SPBANPs were highly stable for several weeks in various phosphate buffers with a range of physiological pH conditions (pH = 6-8). The nanoparticles showed biocompatibility in vivo in C57BL6/J mice that encouraged us to screen the nanoparticles for various biomedical applications. The SPBANPs themselves exhibited remarkable inhibition of cancer cell proliferation (B16F10, A549, MCF-7, and SK-OV-3) in vitro. Substantial inhibition of melanoma tumor growth was observed in the C57BL6/J mouse model (aggressive murine melanoma model: B16F10) after intraperitoneal administration of the SPBANPs without any anticancer drug. Additionally, the SPBANPs exhibited excellent antibacterial activity in various Gram-negative (<i>Escherichia coli</i>, <i>Klebsiella pneumonia</i>, and <i>Pseudomonas aeruginosa</i>) and Gram-positive (<i>Bacillus subtilis</i>) bacteria. Interestingly, this nanoformulation itself works as a drug delivery vehicle, as well as an anticancer and antibacterial agent. The in vitro and in vivo results together demonstrate that this biocompatible nanoformulation (SPBANPs) without an anticancer drug or antibiotic could be explored to develop as a multifunctional therapeutic agent (2-in-1) for the treatment of cancer and bacterial infections in the near future.