Twisted-chiral mesoporous silica from coconut husk waste designed for high-performance drug uptake and sustained release

With an annual production of 2.81 million tons, the coconut husk is an essential source of silica. Various advantages of silica as a drug carrier make it one of the most developed materials in drug delivery applications. To improve the drug delivery performance of a material, twisted chirality is also classified as a critical factor because the pharmacological activity depends on the interaction of the drug with the drug carrier material in the target area. In this study, the coconut husk-based mesoporous silica (MS) can be synthesized through a calcination and sol-gel method. With the help of anionic surfactant, MS is successfully modified to have a twisted-chiral structure (CMS). CMS is characterized by twisted rod-like morphology at a size of 1-2 mu m, with a helical arrangement (mixed with the beta-sheet and random coil conformations). CMS's surface area and pore volume are obtained at 288.3 m(2)/g and 0.614 cm(3)/g, with an average pore size of 7.63 nm. The maximum adsorption of tetracycline (506.5 mg/g) is reached at pH = 4, with the initial concentration of tetracycline at 400 mg/g, temperature of 323 K, and adsorption time of 600 min. The loading of tetracycline follows the pseudo-first-order model with a monolayer mechanism. The bulk migration of tetracycline from the solution into the surface of CMS is deemed the primary adsorption mechanism. The in-vitro release study of tetracycline at pH = 7.4 follows the slow-sustained release model with the cumulative release at 72.3 %, showing better release performance compared with the common MS.