A nanohybrid of the charge-neutral and poorly water-soluble anticancer drug camptothecin (CPT)/graphene oxide (GO)/Mg-Al hydrotalcite-like compounds (HTlc) was synthesized using a coassembly route. For the coassembly route, CPT molecules were initially loaded on the surface of GO nanosheets; the resulting negatively charged CPT-loaded GO nanosheets and the positively charged HTlc nanosheets were then coassembled together into the layered CPT/GO/HTlc nanohybrid, in which the GO nanosheets and the HTlc nanosheets were alternatively stacked and the CPT molecules were located in its interlayer gallery. The so-obtained nanohybrid was characterized using X-ray diffraction, transmission electron microscope, atomic force microscope, scanning electron microscope-energy dispersive spectrometer, Fourier transform infrared spectrometer, ultraviolet-visible spectrophotometry and thermogravimetric analysis/differential scanning calorimetry technique. The mass ratio of GO to HTlc nanosheets in the nanohybrid was 0.63. The loading amount of CPT on the GO nanosheets was 61.0 mg/g, and that in the nanohybrid was 13.4 mg/g. The d-spacing of the CPT/GO composite and the nanohybrid were 0.84 and 1.35 nm, respectively. The in vitro release of CPT from the nanohybrid was examined in pH 7.4 and 4.0 phosphate buffer solutions at 37 ℃. The results showed that the drug release process could be described with pseudo-second order kinetic model, and exhibited strong pH dependence, namely, the release rate and the percentage release in pH 4.0 buffer were evidently higher than those in pH 7.4 buffer. The pH dependence of CPT release is due to a possible difference in the release mechanism. The CPT release in pH 7.4 buffer was a diffusion-controlled process and the intraparticle diffusion was the rate-limiting step; in pH 4.0 buffer, the dissolution of HTlc layers and the weakening of π-π interaction between CPT and GO also played an important role for CPT release. The maximum percentage releases of CPT from the nanohybrid in pH 7.4 and 4.0 buffers were about 26.8% and 31.1%, respectively, higher than that from CPT/GO composites. The coassembly method is a simple route for building drug/GO/HTlc nanohybrids, and the nanohybrids have potential applications in drug delivery.

Key words: hydrotalcite-like compounds, graphene oxide, camptothecin, drug release, coassembly