Covalent Gelatin-Cyclodextrin Nanocarrier Systems for Pistacia atlantica Essential Oil: Physicochemical...

Essential oil from Pistacia atlantica gum is rich in bioactive terpenes but limited by volatility and poor stability. Here, a chemically integrated nanogel system was developed by covalent conjugation of carboxymethyl-β-cyclodextrin (CM-β-CD) to gelatin (CNG), followed by supramolecular stabilization with Tween 20 (CNGT) for essential oil encapsulation (CNGTO) using O/W emulsification and freeze-drying. Two formulations with different loadings were prepared: CNGTO(1) (46.5%) and CNGTO(2) (56.5%). Dynamic light scattering revealed mean particle sizes ranging from 176.3 nm (CNG) to 693 nm (CNGTO(2)), depending on formulation and oil content. Encapsulation efficiencies reached 77.5% ± 1.4% and 81.4% ± 1.7% for CNGTO(1) and CNGTO(2), respectively. Encapsulation reduced the release rate compared to free oil, showing a biphasic release profile over 96 h. Although total antioxidant capacity of encapsulated samples (128.4-145.2 µg ascorbic acid equivalents g^-1) was slightly lower than free oil (166.8 µg g^-1), DPPH radical scavenging activity was enhanced. Total phenolic content reflected contributions from both oil and matrix. Four-week storage studies demonstrated improved physicochemical and antioxidant stability. Molecular docking analysis using α-pinene (33.65%, GC-MS) provided mechanistic insight into terpene-cyclodextrin interactions within the hybrid matrix and the structural role of Tween 20 in modulating inclusion behavior.