Objective: Taking betaxolol hydrochloride as model drug

to prepare drug loading montmorillonite-chitosan nanoparticles by ionic gelation of chitosan with sodium polyphosphate (TPP)

which is known simply as Mt-BH/CS NPs.Method: Mt-BH/CS NPs was prepared by ionic gelation

orthogonal test was adopted to optimize its formulation process by taking encapsulation efficiency and drug loading as indexes.Encapsulation efficiency

drug loading and in vitro release properties of Mt-BH/CS NPs were examined by UV method and its biological properties of nanoparticles suspension were investigated by mucoadhesive test and in vitro cytotoxicity test.Result: The best formulation process was as following:chitosan concentration of 1.5 g·L-1

TPP concentration of 1.2 g·L-1

chitosan-TPP (10:1)

betaxolol hydrochloride concentration of 2 g·L-1.The average encapsulation efficiency of five batches of Mt-BH/CS NPs was 36.13% and its average drug loading was 14.50% with RSD<1.0% by dialysis method.The cumulative release rate of Mt-BH/CS NPs was 82.23% in 10 h.In the mucoadhesive test

after mixing with mucous membrane

the reduction of Zeta potential value of Mt-BH/CS NPs indicated that there was mucoadhesive property of Mt-BH/CS NPs.The cell viability of human immortalized corneal epithelial cells after being exposed to betaxolol hydrochloride solution and Mt-BH/CS NPs showed that cytotoxicity of betaxolol hydrochloride solution was higher than that of Mt-BH/CS NPs suspension.Conclusion: Mt-BH/CS NPs has a high drug loading

slow in vitro release

low toxicity and great mucoadhesive property

which may hold promise to be an attractive novel nanosystem for the treatment of ocular diseases.The new drug delivery system can improve the capability of release properties and enhance the interaction with the eye

so as to improve the ocular bioavailability of drugs and reduce their adverse reactions.