Self-Fluorescent Arginine-Functionalized Hydroxyapatite Nanoparticles for Efficient siRNA Delivery and Gene Silencing in Pluripotent Stem Cells and Bioimaging Applications

Nanoparticles with high transfection efficiency and bioimaging applications offer a versatile tool for basic research and clinical applications in fields such as gene therapy, regenerative medicine, and diagnostics. In this article, we synthesized an undoped, self-fluorescent monomeric arginine (R) functionalized hydroxyapatite nanoparticles (RHNPs) as a cost-effective and stable gene delivery agent, also useful for bioimaging applications. Synthesized by a modified sol-gel method, RHNPs have a diameter ranging from 30 to 40 nm, display pure phase, and possess a positively charged surface with a significant zeta potential of 6.98 mV. RHNPs also show an excellent binding capacity for siRNA and enhanced cellular uptake. RHNP-mediated siRNA delivery in mouse embryonic stem cells (mESCs) demonstrated a twofold higher knockdown efficiency than a commercial transfection reagent at a twofold lower concentration (25 nM). The self-fluorescent property of RHNPs helped to demonstrate its efficient uptake and biodistribution both in vitro and in vivo. Toxicity evaluation of RHNPs showed no acute adverse effect on body weight and hematological parameters in mice models when administered in vivo, even at the highest concentration tested. These findings collectively establish RHNP as an excellent self-fluorescent gene delivery agent with the potential for in vitro and in vivo biomedical applications.