Preparation Of Drug Loading Montmorillonite-chitosan/TPP Nanoparticles And Study Its Corneal Cytotoxicity And Permeability

Eye drops is the first method choice of delivery in ocular therapy. However, due to the special physiological barrier of the eye, the bioavailability of an instilled compound is generally low. Therefore, development of a novel drug delivery platform for ocular application which to improve drug bioavilability is very necessary. Results to date strongly suggest that ocular medicine will benefit enormously from the use of this nanometric scale technology. In this study, drug loading Montmorillonite-chitosan nanoparticles were prepared by nanotechnology using chitosan and montmorillonite(MMT) as carriers with the combination of their characteritics. The nanoparticles may hold promise to be an attractive novel nanosystem for the treatment of ocular diseases.Drug loading Montmorillonite-chitosan/TPP nanoparticles were prepared by ionic gelation of chitosan with sodium tripolyphosphate(TPP). Betaxolol hydrochloride(BH) was selected as a model drug. In this study, an orthogonal array design of L9(34) was performed to optimize chitosan concentration, TPP concentration, mass ratio of chitosan and TPP, drug concentration. Encapsulation efficiency and drug loading capacity were determined to obtain the optimized formulation. The particle distribution and zeta potential were studied by DLS. The results showed that the size range of the nanoparticles was between 338.4 and 585.5 nm with positive zeta potential values from 24.62 m V to 36.42 m V. The encapsulation efficiency, drug loading capacity, particle size, zeta potential value of optimized formulation were 36.13±0.16%,14.50±0.06%,460 nm and 29.18 m V, respectively. Morphology of optimized nanoparticles was obsvered using transmission electron microscope(TEM). The nanoaprticles were spherical in shape with rough surface. The in vitro release was studied by dialysis membrane technique. Drug release from optimized nanoaprticles was controlled with approximately 60% of the original amount released over a 10 h. The release profile of nanoparticles followed Ritger-Pappa release kinetics. These nanoparticles were characterized by thermogavimetric analysis(TGA), Fourier transform infrared spectroscopy(FT-IR) and X-ray diffractometry(XRD). The decomposition temperature of drug which encapsulated into nanoparticles increased to about 450℃, two new characteristic peaks were found in the FT-IR spectrum of nanoparticles and no characteristic peaks of chitosan and MMT were found in its diffracograms, indicating that the MMT containing drug was successfully encapsulated into chitosan nanoparticles. In the mucoadhesive test, the reduce of zeta potential value of optimized nanoparticle from 29.18 m V to 25.88 m V indicated that the ionic interaction between negatively charged sialic acid residues in mucin and positively charged amino groups in CS nanoparticles that resulted in the mucoadhe-sive properties of the tested CS nanoparticles was ocurredThe in vitro corneal permeability and rabbit eye irritation of nanoparticle were investigated. The results of corneal permeability test showed that the apparent permeability coefficient of optimized formulation was between the drug solution and commercial drug(Betopotic). The optimized formulation was found non-irritant and tolerable when tested by modified Draize test.The immortalized human corneal epithelial cell line(HCEC) was constructed for the study of cytotoxicity and in vitro corneal permeability of nanoparticles. The results of MTT test revealed that cytotoxicity of the BH solution and betopotic were higher than that of optimized formulation nanoparticles. Among them, the cytotoxicity of BH solution was concentration and time-dependent. All optimized formulation nanoparticles showed no toxicity on the human corneal epithelial cells when the amount of addition was low, However, they showed a certain extent toxicity on cell when the amount of addition was above 50 ul. The results for in vitro corneal permeability test found that apparent permeability coefficient of optimized formulation was between the drug solution and commercial drug(Betopotic). It was also found that the amounts of permeation across cells for all samples are higher than that of isolated rabbit cornea.The results indicated that a novel ocular drug delivery nanosystem consists of chitosan and montmorillonite presented a broad prospect.