Adaptive Chitosan Hollow Microspheres as Efficient Drug Carrier

Smart drug carrier with function-oriented adaptations is highly desired due to its unique properties in medical applications. Herein, adaptive chitosan hollow microspheres (CHM) are fabricated by employing interfacial Schiff-base bonding reaction. Hydrophilic macromolecules of glycol chitosan are fixed at the oil/water interface through numerous hydrophobic small molecules of borneol 4-formylbenzoate, forming the CHM with a positively charged surface and lipophilic cavity. These CHM have an average size of 400-1000 nm after passing through the 0.22 μm apertures of filter paper. This phenomenon combined with SEM measurements demonstrates its remarkable shape-adaptive behavior. Furthermore, the CHM present a pH-dependence of structural stability. When pH value reduces from 7.06 to 5.01, the CHM begin to lose their integrity. All those characteristics make the CHM an intelligent drug carrier, especially for water-insoluble anticancer drugs, paclitaxel (PTX) in particular. Both cell uptake and cell cytotoxicity assays suggest that the PTX-loaded CHM are highly efficient on HepG2 and A549 cells. Therefore, rather than most of the traditional materials, these adaptive CHM show great potential as a novel drug carrier.