Delamination-Reassembling Synthesis And Characterization Of Ibuprofen-LDH Nanohybrids

Layered double hydroxides (LDHs), also known as anionic or hydrotalcite-like clays, are a class of lamellar compounds that consist of positively charged brucite-like host layers and hydrated exchangeable anions located in the interlayer gallery for charge balance. The interlayer region (or gallery) of LDHs may be considered as a microvessel in which drug molecules may be stored, i.e., some drug molecules may be intercalated into the gallery of LDHs to form drug-LDH nanohybrids. The drug-LDH nanohybrids may evidently inhibit the release of drug molecules stored in LDH, therefore, LDHs may be potentially used in drug controlled-release systems.Up to now, many methods for synthesis of drug-LDH nanohybrids were developed, such as coprecipitation, ion exchange, reconstruction and hydrothermal methods. However, these conventional methods have the following serious drawbacks: complex processes, time-consuming, high reaction temperature and accompanying large sewage.In this paper, a drug Ibuprofen (IBU) was chosen as the guest molecule and Mg-Al LDHs as the host material, a facile fabrication method, delamination/reassembling process, of IBU-LDH nanohybrids was studied. First, LDH particles were delaminated to well dispersed2D nanosheets, then the LDH nanosheets and drug molecules coassemblied to form drug-LDH nanohybrids. The so-synthesized nanohybrids were characterized by XRD, FT-IR, TEM and elemental microanalysis, respectively, and the IBU release behavior was examined also. The results show that the release kinetics of IBU from the nanohybrids obeyed the pseudo-second order kinetic model and the diffusion through the LDH particle of IBU played an important role in controlling the drug release rate.The main contents and conclusions are as follows:(1) The Mg-Al-NO3LDHs, Mg-Al-Cl-LDHs and Mg-Al-Gly LDHs were synthsized by a coprecipitation method, and the elemental analysis results show that the Mg/Al molar ratio of the products was lower than that of the raw mixed salt solutions.(2) The Mg-Al-NO3-and Mg-Al-Gly LDH samples can be delaminated in formamide, and their maximum delamination amounts are80g/L and10g/L, respectively, while Mg-Al-Cl-LDHs can not be delaminated in formamide.(3) IBU-LDH nanohybrids were successfully synthesized via a delamination-reassembling process. A probably morphology of IBU molecules in the nanohybrid is that the IBU molecules arrange as a slightly tilted bilayer with the long axis perpendicular to the brucite-like layer, compared with the conventional methods, the delamination/reassembling method shows various remarkable advantages, such as simple procedure, short react time, wildly condition, easily loading of drug and so on.(4) The in vitro IBU release examinations from the nanohybrids showed that the IBU-LDH nanohybrids were a potential drug controlled release system. The kinetic analysis showed that the release kinetics of IBU from the nanohybrids obeyed the pseudo-second order kinetic model and the diffusion through the LDH particle of IBU played an important role in controlling the drug release rate.