| Insertion of punctum plugs has been demonstrated to be an effective treatment for dry eye syndrome. The plugs are mainly made of thermo-sensitive material. It was a kind of hydrophobic acrylic material which has two "smart" properties. The first "smart" property is its transition from rigid solid to soft gel at around30℃, which makes the insertion become very convenient. The second "smart" property manifests itself while it is expanding in diameter from0.4mm up to1mm during the temperature induced solid to gel transition. This expansion in diameter is accompanied by a decrease in the length of SmartPlug. However, the removal of SmartPlugs is quite inconvenient, doctors have to introduce a cannula into the lower punctum and-irrigate using a syringe of saline solution. In this paper, a kind of poly acrylic acid gel had been prepared, they possessed of all advantages of Smartplug, its swelling radios and gel strength could change according to the change of pH in the environment, besides they were degradable.First of all, effects of three different cross-link agents, including TEA, BIS and DEA, on polymer’s cross link degree and range of volume transformation had been discussed, results shown BIS was the right one, and when its dosage was0.1g, adding6ml acrylic acid could insure the prepared gel had suitable swelling ratio and the change of this ratio would be well-regulated when pH value of the environment changed.Five kind of pore-forming agents, including PEG-400, Chitosan, the polymer of Chitosan and glutin, CaCO3and Na2CO3, had been used to prepare fast responsive, PH sensitive Polyacrylic acid (PAAc). The mechanism and effects of pore-forming agents on PAAc gel had been studied, besides, the experiment also discussed the effect of the three most effective pore-forming agents on gel’s water retention and swelling rate. The result showed that the most suitable dosage of PEG-400, the polymer and Na2CO3were1ml,0.8ml and lml respectively and PEG-400was most effective with the same dosage, the gel used PEG-400as pore-forming agent could finish more then95%of swelling process in just5minutes. The gel strength of gels with three different pore-forming agents changed a lot during swelling. In acid or alkaline condition, the swelling ratio of gels were quite small, thus gels had high intensities, in neutral condition, gels reached the largest swelling ratio and at the same time became soft. All the gels had great inhibition to bacteria especially the gel which was cross-linked with the polymer. Haemolysis Test proved that they were safe to be used in human’s eyes. Take the gel which were cross-linked with PEG-400as an example, it could be biodegraded98%in28days and was suitable to be used as punctum plug material.At last, acrylic acid was copolymerized with Hyaluronic Acid and prepared a new kind of superabsorbent gels which had good gel strength and resistant to saline solution. Addition of all components were researched, it demonstrated that when the addition of acrylic acid was6ml, Hyaluronic Acid addition was0.18g and the molar ratio of cross-linker to monomer was0.015, the gel shown the best resistant to Saline Solution, the optimum absorbency for0.9%NaCl solution were122.695g/g, and for phosphate buffer that were90.298g/g, at the same time, it also improved the gel strength which reached4.015×105pa. Compared with the gel copolymerized with Sodium Polymannuronate, new gel was more suitable to be used in human eyes. |
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