Antibacterial perillaldehyde/hydroxypropyl-γ-cyclodextrin inclusion complex electrospun polymer-free nanofiber: Improved water solubility, thermostability, and antioxidant activity

Abstract Perillaldehyde (PA) is an environment-friendly and green natural active ingredient extracted from plants which has been proved to possess antibacterial and antioxidant properties. However, the volatile nature and water-insolubility of PA limit its application. In our study, perillaldehyde/hydroxypropyl-γ-cyclodextrin inclusion complex nanofiber (PA/HPγCD-IC-NF) was produced by electrospinning without blending with a polymer matrix. The surface of free-standing PA/HPγCD-IC-NF was proved to be beadless and uniform in size and thickness using a scanning electron microscope. Thermogravimetric analysis showed that the thermal stability of PA was enhanced after the synthesis of inclusion complex. The structural studies of X-ray diffraction, nuclear magnetic resonance, Fourier transform infrared spectroscopy, and molecular modeling techniques demonstrated that PA was successfully encapsulated in cyclodextrin cavity to obtain the most beneficial binding interactions of PA and HPγCD. Meanwhile, phase solubility study illustrated an improvement of water solubility on PA due to the formation of inclusion complex. Furthermore, DPPH free radical scavenging experiment and bacterial inhibition tests displayed the characteristics of antioxidant and the excellent antibacterial performance of PA/HPγCD-IC-NF, respectively. In summary, an oily and water immiscible liquid, PA can be stored as a solid inclusion compound that was fast-dissolving character, high-temperature stability, higher water solubility, and preferable antioxidant activity after forming PA/HPγCD-IC-NF.