Metformin-loaded bioinspired mesoporous silica nanoparticles for targeted melanoma therapy: Nanotopographical design with in vitro and in vivo evaluation.

Bioinspired nanotopographical carriers have emerged as innovative cancer therapy strategies, mimicking natural processes to enhance targeted delivery and reduce systemic toxicity. This study presents the development of virus-like mesoporous silica nanoparticles (MSN) as a delivery platform for repurposed metformin (MTF) in a topical multi-stimuli responsive system for melanoma treatment. Metformin-loaded virus-like MSN (MTF-MSN) were fabricated and incorporated into a thermo-responsive gelling system. The particles were evaluated for morphology, zeta potential (ZP), particle size (PS), entrapment efficiency (EE%), Fourier-transform infrared (FT-IR) spectroscopy, MTT cytotoxicity assay, in vitro release, and in a melanoma in vivo model. The particles exhibited a spherical morphology, a zeta potential of +31.9 ± 1.45 mV, and a particle size of 197 ± 3.47 nm, ideal for skin penetration. MTF-MSN demonstrated significant antiproliferative activity against melanoma A375 cells, with lower IC values (192 μg/mL) compared to free MTF (>300 μg/mL). Sustained, pH-sensitive MTF release was observed over 48 h at pH 7.4 and 6 h at pH 5.5. In vivo studies showed enhanced anti-cancer efficacy of MTF-MSN, evidenced by elevated caspase-3 and Neurofibromin Type-1 (NF-1) levels, along with suppressed angiogenesis markers VEGF and NRAS. The MTF-MSN-treated group exhibited superior outcomes compared to free MTF and controls (p < 0.05). This innovative bioinspired MTF-MSN hydrogel system optimizes MTF delivery for melanoma therapy, pioneering advancements in drug repurposing and nano-oncology.