Study On Preparation And Released Drug Delivery Of Hydrogel For Contact Lens

In this paper, AM-HEMA-NVP copolymer hydrogels with pH-sensitive property were synthesized by copolymerization of Acrylamide(AM),Hydroxyethylmethacrylate (HEMA) and N-Vinylpyrrolidone(NVP). Design theory, synthetic conditions, swelling behavior and delayed drug delivery behavior of the hydrogels were investigated respectively.According to the pH-sensitive principle, the crosslinking structure and its forming mechanism of hydrogels, as well as the types of the delayed drug release system, AM, HEMA, and NVP were recommended as monomers for synthesizing pH-sensitive copolymer hydrogels.Synthetic conditions of the AM-HEMA-NVP copolymer hydrogels were optimized. The results showed that the optimal copolymerization temperature was 80℃, reaction time was 30 hours, initiator (benzoylperoxide (BPO) ) content was 0.1% (wt%) .Under the optimal conditions, the reaction mixtures were changed into colorless, transparent glassy hydrogel. HEMA monomer has the higher reaction activity than AM and NVP.Optical and mechanic properties were studied as well, the results showed that the hydrogels were optical transparent with more than 94% transitance for visual light, and the refraction index was 1.37±0.01 or so. The tensile intensity of the hydrogels were in the range of 400-900 kPa. As the increase of AM or NVP content, the tensile intensity of the hydrogels decreased.The swelling behavior of the hydrogels was studied. The results showed that the AM-HEMA-NVP hydrogels were pH-sensitive, and the equilibrium swollen of the hydrogels increased with the increase of AM or NVP monomer content. The equilibrium swollen of the hydrogels decreased when the pH was changed from acidity to neutrality, while increased with the pH changed from neutrality to basicity. As the ionic intensity increased, the equilibrium swollen of the hydrogels decreased; However, the equilibrium swollen of the hydrogels was not sensitive to solution temperature.Excessively swelling of the hydrogels was found and investigated, and the reason for deviation different from Fick's Model was given: the slack time of the molecular chain stretch can't be neglected.Finally, delayed release of chloramphenicol by the copolymer hydrogels was investigatedr. The results showed that the adsorption amount of chloramphenicol by the copolymer hydrogels increased with the increase of chloramphenicol concentration of the solution and NVP or AM content of the hydrogels, while decreased with the increase of NaCl concentration of the solution. The release rate of chloramphenicol increased with the increase of NVP or AM content of the hydrogels, and the release kenetics can be described by Fick's deffusion kenetics, the release of chloramphenicol was controlled by the swelling process of the hydrogel and the diffusion process of chloramphenicol.