Improvement in Mechanical Properties and Anti-Adhesion Activity in Maxillofacial Silicones with Pumpkin Extract Nanoparticles

Background/Objectives: The deterioration of maxillofacial silicone elastomers is caused by microbial colonization and mechanical failure. Traditional inorganic nanofillers influence the elasticity of materials and their surface hygiene. This study provides a two-phase evaluation of mechanically milled pumpkin (Cucurbita pepo) extract nanoparticles (PE-NPs) to evaluate the in vitro anti-adhesion efficacy, mechanical properties, and surface characteristics of VST-50 maxillofacial silicone. Methods: In Phase I (Screening Phase), a comparison was made between conventional direct mixing and a newly developed multi-step catalyst-mediated mixing method. The preliminary assessment of anti-adhesion activity against Staphylococcus epidermidis (S. epidermidis), Shore A hardness, and tear strength was carried out at concentrations of 0, 0.5, 1.0, 1.5, and 2.0 wt.%. In Phase II (Characterization Phase), using the optimized fabrication protocol, final assessment of ultimate tensile strength (UTS), percentage elongation, profilometer surface roughness (Ra), and optical contact angle (Wettability) was carried out. Microstructural characterization was executed using FTIR, FE-SEM/EDX, XRD, and 3D Atomic Force Microscopy (AFM). Results: Phase I displays that the catalyst-mediated mixing effectively facilitated processing within the siloxane matrix, resulting in homogeneous nanoparticle dispersion. PE-NPs exhibited a concentration-dependent anti-adhesion response, achieving 95.7% anti-adhesion activity at 2.0 wt.% while improving tear strength and balancing hardness. Phase II demonstrated that 1.5 wt.% represented the concentration providing the most favorable overall balance, significantly enhancing tensile strength (10 [10–10.25] MPa) and elongation percentage (592.26 ± 47.97%). Macro-roughness and contact angles remained statistically unchanged (p > 0.05), maintaining baseline surface wettability. However, AFM nanomorphology revealed that 1.5 wt.% PE-NPs effectively filled matrix micro-voids, decreasing nanoscale roughness to 18.88 nm. Agglomeration was captured at 2.0 wt.%, resulting in suboptimal mechanical performance. Conclusions: Incorporating 1.5 wt.% organic PE-NPs via a multi-step catalyst integration technique provides an eco-friendly, strong strategy among the evaluated concentrations to enhance initial in vitro mechanical and anti-adhesion properties among the evaluated concentrations without altering baseline surface roughness.