Castor Oil

Castor oil-based hybrid microparticles were synthesized for controlled drug release using a green sol-gel technique. Castor oil was modified on a bulk scale with 3-isocyanatopropyltriethoxysilane (IPTES) at 60 ℃ for 30 min under nitrogen. Complete consumption of hydroxyl groups led to silylated triglycerides (ICO). The functionalized oil was emulsified into water (1: 10 w/w) containing thermo-reversible κ-carrageenan or Pluronic F127. Following emulsification using either a four-blade propeller or Ultra-Turrax, the continuous phase was either cooled to 4 ℃ or heated to 60 ℃ to gelate and immobilize the droplets. Ambient moisture over 72 h induced sol-gel condensation of ethoxysilanes. Covalent Si-O-Si networks formed and transitioned liquid droplets into spherical solid particles. The particles were recovered by inversion gelation, washed, centrifuged, and freeze-dried.
Ibuprofen was dissolved within the ICO prior to loading. Loading efficiencies ranged from 55-98%; κ-carrageenan held more drug because pluronic micelles shifted ibuprofen into the external phase. κ-carrageenan-based beads released 100% drug in pH 7.4 buffer at 37 ℃ within 10 h via diffusion. Smaller particles or those based on pluronic show incomplete or biphasic release profiles.

Fig. 1 Castor oil-based hybrid microparticles via a thermo-stabilized o/w emulsion process and sol-gel chemistry. (Gallon G.; et al. 2017)

Castor-oil-reinforced polymer hybrid hydrogels were prepared via three freeze-thaw cycles for skin-tissue augmentation by Muzammil K M et al. Chitosan was mixed separately with sodium CMC, HPMC, carbopol or Pluronic F68, followed by a dispersion of castor-oil emulsion. These mixtures were frozen at −20 ℃ and thawed at 25 ℃. FTIR indicated inter-polymeric hydrogen bonding and formation of polyelectrolyte complexes; SEM showed micro-porous rough surfaces. For wound healing evaluation in rat excision wounds, chitosan-Pluronic hybrid (H4) recorded 93.6% wound closure at day 12 with better results than a commercial povidone-iodine standard. Histopathology studies at day 12 showed enhanced re-epithelialisation with dense granulation tissue as well as the presence of abundant neovessels. These hybrids were found to be non-irritant and provided a moist environment with antibacterial characteristics and enhanced keratinocyte and fibroblast proliferation.

Fig. 2 Castor oil-reinforced polymer hybrid hydrogels for skin-tissue augmentation. (Muzammil K M.; et al. 2021)