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目的制备载天冬酰胺酶(asparaginase,AN)透明质酸-聚乙二醇[hyaluronic acid-graft-poly(ethylene glycol),HA-g-PEG]/α-环糊精(α-cyclodextrin,α-CD)纳米囊(HA-g-PEG/α-CD hollow nanocapsules loaded with asparaginase,AHAPs),并对其体外活性及稳定性进行初步考察。方法采用自组装法制备AHAPs,测定AHAPs的最适温度、最适pH、粒径、zeta电位和包封率,并通过热稳定性、酸碱稳定性、抗胰蛋白酶水解能力、抗金属离子和有机化合物能力、血浆稳定性和贮存稳定性实验对游离AN与AHAPs的体外稳定性差异进行考察。通过荧光实验对AN与空白HA-g-PEG/α-CD纳米囊的相互作用进行研究。结果 AHAPs的最适温度为50℃,最适pH值为7.0,测得平均粒径为(424.53±7.25)nm,zeta电位为(-48.77±0.99)mV。经计算,AHAPs的平均包封率为(64.40±1.82)%。稳定性实验结果显示,AHAPs中AN的体外稳定性及活性明显优于游离AN,且部分实验结果差异具有统计学意义(P<0.05)。荧光实验结果表明,AHAPs中AN生物活性的提高可能与AN和空白HA-g-PEG/α-CD纳米囊的相互作用引起蛋白质残基微环境和酶构象改变相关。结论 AHAPs不仅提高了AN的活性,而且明显增强了AN的体外稳定性。
OBJECTIVE To prepare asparaginase (AN) hyaluronic acid-graft-poly (ethylene glycol) (HA-g-PEG) / α-cyclodextrin (HA-g-PEG / α-CD hollow nanocapsules loaded with asparaginase, AHAPs) were prepared and their in vitro activity and stability were investigated. Methods AHAPs were prepared by self-assembly method. The optimal temperature, pH, particle size, zeta potential and entrapment efficiency of AHAPs were determined. Their thermal stability, acid-base stability, antitrypsin hydrolysis ability, Organic compounds ability, plasma stability and storage stability experiments in free AN and AHAPs in vitro stability differences were investigated. The interaction of AN with blank HA-g-PEG / α-CD nanocapsules was investigated by fluorescence experiments. Results The optimum temperature for AHAPs was 50 ℃ and the optimum pH value was 7.0. The average particle size was (424.53 ± 7.25) nm and the zeta potential was (-48.77 ± 0.99) mV. The calculated average entrapment efficiency of AHAPs was (64.40 ± 1.82)%. The results of the stability test showed that the stability and activity of AN in AHAPs were significantly better than that of free AN, and some of the experimental results were statistically significant (P <0.05). Fluorescence experiments showed that the increase of AN activity in AHAPs may be related to the changes of protein residues microenvironment and enzyme conformation by the interaction between AN and blank HA-g-PEG / α-CD nanocapsules. Conclusion AHAPs not only improve the activity of AN, but also significantly enhance the stability of AN in vitro.