Development and Optimization of Biotinoyl Tripeptide-1 Loaded Solid Lipid Nanoparticles for Protection against Heat Induced Hair Damage

Abstract

Aims: This study aimed to develop and optimize biotinoyl tripeptide-1 (BTP)-loaded solid lipid nanoparticles (SLNs) and to evaluate their protective efficacy against heat-induced structural and thermal damage in hair fibers.Methods: A Box-Behnken experimental design was employed to optimize the formulation. The optimized BTP-SLNs were characterized for particle size, Polydispersity Index (PDI), zeta potential, and entrapment efficiency. Hair samples were exposed to repeated thermal cycles at 200°C over 15 days to simulate the thermal straightening damage. Morphological and thermal damage were also investigated using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC).Results: The optimized BTP-SLN formulation demonstrated a particle size of 207.3 nm, PDI of 0.297, zeta potential of -10.6 mV, and an entrapment efficiency of 46.2%. Heat-treated control samples exhibited pronounced cuticle lifting, cortical disruption, and decreased α-keratin denaturation enthalpy. Empty-SLNs provided partial surface-level protection; the incorporation of BTP significantly enhanced thermal resistance. Additionally, BTP-SLN-treated hair showed improved cuticle integrity, reduced microfibrillary separation, increased denaturation peak intensity, and delayed onset of thermal degradation. Conclusion: BTP-loaded SLNs demonstrated protective effects against heat-induced hair damage, likely through a dual mechanism involving lipid barrier formation and stabilization of the keratin matrix. These findings suggest that BTP-SLNs represent a promising strategy for improving thermal protection in cosmetic hair care applications.