One-step bulk preparation of calcium carbonate nanotubes and its application in anticancer drug delivery

Bulk fabrication of ordered hollow structural particles (HSPs) with large surface area and high biocompatibility simultaneously is critical for the practical application of HSPs in biosensing and drug delivery. In this article, we describe a smart approach for batch synthesis of calcium carbonate nanotubes (CCNTs) based on supported liquid membrane (SLM) with large surface area, excellent structural stability, prominent biocompatibility, and acid degradability. The products were characterized by transmission electron micrograph, X-ray diffraction, Fourier transform infrared spectra, UV-vis spectroscopy, zeta potential, and particle size distribution. The results showed that the tube-like structure facilitated podophyllotoxin (PPT) diffusion into the cavity of hollow structure, and the drug loading and encapsulation efficiency of CCNTs for PPT are as high as 38.5 and 64.4 wt.%, respectively. In vitro drug release study showed that PPT was released from the CCNTs in a pH-controlled and time-dependent manner. The treatment of HEK 293T and SGC 7901 cells demonstrated that PPT-loaded CCNTs were less toxic to normal cells and more effective in antitumor potency compared with free drugs. In addition, PPT-loaded CCNTs also enhanced the apoptotic process on tumor cells compared with the free drugs. This study not only provides a new kind of biocompatible and pH-sensitive nanomaterial as the feasible drug container and carrier but more importantly establishes a facile approach to synthesize novel hollow structural particles on a large scale based on SLM technology.