| Polyaspartic acid(PASP)is a functional polymer material with carboxyl hydrophilic groups,which has high water absorption swelling,biodegradability and good biocompatibility.It has become one of the hot spots in the research of hydroabsorbent resins as it can find uses in water treatment,biomedicine,bone tissue targeting and daily hygiene products.However,there are defects such as single structure,low salt resistance and mechanical properties,poor thermal stability and toxic cross-linking agents(amines).In addition,most drugs are alcohol soluble and fat soluble.The low alcohol solubility of PASP absorbent resin leads to low drug loading,which greatly limits its application in biopharmaceuticals and other fields.In the paper,modified polysuccinimides(KPSI)were synthesized by modifying polysuccinimides(PSI)with γ-aminopropyltriethoxysilane(KH550).And KPASP/St water absorbent resin and KPASP/St-g-(AA-AMPS)composite water-absorbent resin were respectively prepared by aqueous solution polymerization method with KPSI,potato starch(St),acrylic acid(AA)and 2-acrylamido-2-methylpropanesulfonic acid(AMPS).The synthesis conditions were optimized,and the composition and morphological structure of the resins were characterized and analyzed.Then,the pH sensitivity,temperature sensitivity,salt sensitivity and alcohol swelling properties of the resin were investigated.In addition,the drug loading and sustained release properties of the prepared highly absorbent resin as a drug sustained release carrier were investigated using salicylic acid as a model drug.The KPASP/St water absorbent resin was prepared by distributing and mixing in aqueous solution.The optimal preparation conditions were as follows: the best swelling ratio of the KPASP/St water absorbent resin in distilled water,0.9 wt%saline and 30% ethanol solution were 211.455 g/g,44.309 g/g and 153.3 g/g respectively,when the feed molar ration of KPSI and St is 5:1,the amount of starch paste water was 1:16.Among them,the water absorption ratio and alcohol swelling ratio were 1.29 times and 1.3 times of KPASP water absorbent resin.The swelling performance of the resin decreased gradually with the increase of ethanol volume fraction in different ratios of ethanol aqueous solution media.And the resin exhibited better pH sensitivity,salt and temperature sensitivity.The results of drug loading and drug slow release performance tests of model drug salicylic acid in KPASP/St absorbent resin showed that the resin loading was 31.2 mg/g.,and the drug release rates of the drug loaded resin were 11.5% and 17.2% in buffer solutions at pH=1.68 and 6.86 for about 60 h,respectively.Secondly,to improve the drug retardation performance of the resin,(AA-AMPS)was introduced and a graft copolymerization method was used to prepare a KPASP/St-g-(AA-AMPS)composite absorbent resin with better overall performance using ammonium persulfate(APS)as initiator.The results of optimized synthesis conditions showed that the best swelling ratio of the KPASP/St-g-(AA-AMPS)composite water absorbent resin in distilled water,Na Cl solution(0.9 wt%)and 30%ethanol solution were 420.648 g/g,84.637 g/g and 275.503 g/g respectively,which were 1.99,1.91 and 1.8 times of the water absorbent resin of KPASP/St,when the feed molar ration of KPSI,AA,AMPS and St is 0.65:1:0.3:0.13,the dosage of initiator is 5 wt%.Among them,the swelling ratio in deionized water and 30%ethanol solutions is 2.6 times and 2.3 times higher than those of KPASP water absorbent resin.The absorbent performance of the resin in different ratios of ethanol aqueous solution media gradually decreased with the increase of ethanol volume fraction.The sensitivity studies of the resin in different solution media showed that the resin exhibited excellent sensitivity to pH,salt solution and temperature and was more suitable for human drug slow release carrier material than KPASP water absorbent resin.The results of drug loading and drug release performance of the model drug salicylic acid in the resin showed that the drug loading of the resin was41.02 mg/g,and its drug loading rate was increased by 10% compared with that of KPASP/St absorbent resin,and the drug release rates of the resin at pH=1.68 and 6.86 buffer solution were 42.5% and 70.5% at about 50 h,respectively.In summary,the study showed that the overall performance of the resin was significantly improved after grafting the copolymer monomer. |
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