Deciphering the multimethodology binding and dissolution of methyl cinnamate with 2-hydroxypropyl-β-cyclodextrin

The present investigation aimed to fabricate and comprehensively characterize the inclusion complex (IC) and nanofibrous (NF) web of methyl cinnamate (MC) with 2-hydroxypropyl-β-cyclodextrin (HPβCD) using probe sonication and electrospinning, respectively, to enhance its bioavailability and thermal stability. UV–Vis absorption and fluorescence spectroscopy demonstrated 1:1 molecular interactions between MC and HPβCD in aqueous solution, with apparent association constants of 275 ± 10 and 505 ± 8 M⁻¹. Field emission scanning electron microscopy revealed bead-free NF structures for MC-HPβCD-NF, with an average fiber diameter of 345 ± 90 nm, while MC-HPβCD-IC exhibited sheet-like flake morphologies. Powder X-ray diffraction analysis indicated the complete transformation of MC's crystalline phase into an amorphous structure in both IC and NF, in contrast to its physical mixture. Thermal analysis showed that MC in both IC and NF forms exhibited significantly enhanced stability, with decomposition temperatures increasing from 145.5 °C to 349.7 and 366.7 °C, respectively. Structural characterization by Fourier-transform infrared and nuclear magnetic resonance spectroscopy demonstrated distinct changes in both the IC and NF, with clear spatial correlations between the cavity protons of HPβCD and the aromatic protons of MC. Theoretical calculations further elucidated the interaction site of MC within the HPβCD cavity. The water solubility of MC in both IC and NF was approximately tenfold higher than its solubility in pure water. These findings suggest that both encapsulation and electrospinning of MC with HPβCD are effective strategies—particularly the latter—for improving aqueous solubility and thermal stability, making them promising for applications in the food and aroma industries.