6.4.3. Polyols

Polyols are polymers with hydroxyl groups [156]. A representative polymer of this family is the polyvinyl alcohol (PVA), which is synthesized by the hydrolysis of polyvinyl acetate [157,158]. PVA is a water-soluble polymer that can generate hydrogels by chemical or physical crosslinking [159]. Recent advances are presented below.

Li et al. (2019) improved the solubility of curcumin using <sup>d</sup>-<sup>α</sup>-Tocopherol polyethylene glycol 1000 succinate (TPGS), a water-soluble derivative of vitamin E that acts as a surfactant with the ability to form micellar nanoparticles in water. More importantly, TPGS acts as a potent antioxidant. The complex TPGS/curcumin was encapsulated using PVA, in which were obtained stable nanoparticles of 12 nm diameter. The nanoparticle satisfactorily released curcumin in simulated colonic and gastric fluids; furthermore, the nanoparticles decreased intracellular ROS levels and apoptosis and inhibited the migration of HT-29 human colon cancer cells more potently than free curcumin. The pharmacokinetic analysis demonstrated that the nanocapsules were more bioavailable than free curcumin after oral administration to rats [160].

Wen et al. (2019) developed a core-shell electrospun nanofiber, core (PVA and phycocyanin), and shell (Polyoxyethylene) for the targeted therapy of CRC. Phycocyanin (PC), a water-soluble biliprotein (antioxidant), exhibits potent anti-colon cancer properties. The PC-loaded electrospun fiber mat inhibited HCT116 cell growth in a dose-dependent and time-dependent manner. In particular, the PC-loaded mat exerted its anticancer activity by blocking the cell cycle at the G0/G1 phase and inducing cell apoptosis, involving a decrease in Bcl-2/Bax, the activation of caspase 3, and the release of cytochrome c [161].

Golkar et al. (2019) fabricated via electrospinning, *Plantago major Mucilage* (PMM) blended with PVA, in order to produce an electrospun nanofiber. The researchers optimized the electrospinning parameters (voltage, tip-to-collector distance, feed rate, and PMM/PVA ratio) to obtain nanofibers with an average diameter of 250 nm. The viscosity, electrical conductivity, and surface tension of the PMM/PVA solution were 550 Cp, 575 μS/cm, and 47.044 mN/m, respectively [162]. The systems seem promising for biomedical applications. However, the researchers did not evaluate the effects of the fibers for CRC treatment.
