GREEN SYNTHESIS OF COPPER OXIDE NANOPARTICLES USING ALOE BARBADENSIS (ALOE VERA) LEAF EXTRACT: OPTICAL CHARACTERIZATION AND IN VITRO CYTOTOXICITY EVALUATION IN 3T3-L1 MOUSE FIBROBLASTS

Abstract

Background: Copper oxide nanoparticles (CuO NPs) are increasingly explored for biomedical applications owing to their antimicrobial, antioxidant, and wound-healing-promoting properties. Conventional physical and chemical synthesis routes involve toxic reducing and capping agents that limit biocompatibility. Green synthesis using plant extracts offers an eco friendly, low-cost alternative, but the biosafety of the resulting nanoparticles must be established before biomedical use. Objective: To green-synthesize CuO NPs using Aloe barbadensis (Aloe vera) leaf extract as a reducing and capping agent, characterize the nanoparticles by UV–visible spectroscopy, and evaluate their dose-dependent cytotoxic potential on 3T3 L1 mouse fibroblast cells as a preliminary safety assessment prior to downstream biomedical formulation. Methods: Dried Aloe barbadensis powder was extracted in boiling distilled water and filtered. The extract was combined with 30 mM copper sulfate solution and stirred continuously for 48 hours at 600 rpm to yield CuO NPs, which were characterized by UV–visible spectroscopy (250–650 nm) and recovered by centrifugation. Cytotoxicity was assessed by MTT assay on 3T3-L1 fibroblasts exposed to CuO NPs (25–250 µL/mL) for 24 hours (n = 3 per group), and morphological changes were assessed by phase-contrast microscopy. Results: A concentration-dependent decline in cell viability was observed, from 97.38 ± 3.69% at 25 µL/mL to 47.35 ± 9.62% at 250 µL/mL, relative to untreated control (100%). Viability reduction reached statistical significance from 200 µL/mL onward (p < 0.05). The half-maximal inhibitory concentration (IC₅₀) was estimated at approximately 243 µL/mL. Phase-contrast microscopy revealed progressive cell rounding, shrinkage, and reduced confluency at 100 and 200 µL/mL compared with the smooth, spindle-shaped morphology of control fibroblasts. Conclusion: Aloe barbadensis-mediated green synthesis yielded CuO NPs that were well tolerated by 3T3-L1 fibroblasts at concentrations up to approximately 150 µL/mL, with cytotoxicity emerging only at higher doses. These findings support a favourable biosafety margin for low-to-moderate concentrations of green-synthesized CuO NPs and provide a rational dose ceiling for their incorporation into biomedical formulations such as nanoparticle-augmented platelet-rich plasma for chronic wound healing.