Preparation And Characterization Of Chitosan-based Injectable Temperature-sensitive Interpenetrating Network Hydrogel For Dry Eye Treatment

Punctal plug embolization is one of the most effective method for treating dry eye currently.At present,the domestic clinical use of punctal plugs are all dependent on imports,so the development of punctal plugs with good biocompatibility,moderate mechanical strength,good viscoelasticity and independent intellectual property rights has become a hot issue of domestic scholars.In this paper,using sodium?-glycerophosphate?GP?as a temperature-sensitive crosslinking agent for aqueous chitosan derivative hydroxypropyl chitosan?HPCS?or chitosan quaternary ammonium salt?HTCC?and calcium chloride?CaCl₂?as a chelate cross-linking agent of sodium alginate?SA?,temperature sensitive interpenetrating network hydrogel were prepared by blending cross-linking method,which has a chitosan derivative-GP crosslinked structure as the first network and the SA-Ca²⁺crosslinked structure as the second network.The polymer is a flowable sol at room temperature before injection.The sol gels in situ in a physiological temperature environment forms a gel without fluidity after injecting into the lacrimal passage,which could be completely fill the lacrimal duct,reducing the loss of tears to relieve dry eye syndrome.Using Gaussian software,the mechanism of gel temperature-sensitive phase transition based on hydrogen bond formation theory was discussed.The hydrogel properties were characterized by Fourier transform infrared spectroscopy,scanning electron microscopy,thermal stability,compressive modulus of elasticity and rheological.The biocompatibility of the hydrogel components was evaluated by MTT colorimetry,using the mouse fibroblasts as experimental model cell lines.In the animal experiment,the compound diatrizoate contrast agent was mixed into the sol formulation,due to its contrast effect.According to the brightness of the scanning under the computed tomography?CT?which depends on the density difference in the body,the position of the gel blockage and the morphology of the gel in the body were detected;and then the method of treating the dry eye was judged by the method of tear height test,blotting cytology test,fern experiment,histopathological section.When the concentration of HPCS,GP,SA and CaCl₂ in composite gel formulation is 18.75mg/mL,75 mg/mL,18.33 mg/mL and 1.67 mg/mL,respectively,the gel phase transition time is 85±15 s.Compressive elastic modulus is 40±15 kPa,and the ratio of loss modulus G??and G?storage modulus is 0.10±0.025.CT scan confirmed that the hydrogel was implanted into the lacrimal duct,and increasement of tear height was maximum,morphology of conjunctival epithelial cells was normal,the number of goblet cells and the ability to secrete mucin were the strongest with the hydroxypropyl chitosan hydrogel.Experiment results indicated that the prepared HPCS complex sol has the characteristics of injectability and gelation in physiological temperature range,which has controllable gel time and good gel mechanical strength,so it has a better effect in treating dry eye syndrome.