肉桂酸疏水改性透明质酸的聚集及其光谱性质

Aggregation and Spectral Properties of Hydrophobically Modified Hyaluronic Acid with Cinnamic Acid

通过肉桂酸(CA)与透明质酸(HA)的酯化反应,制备了肉桂酸疏水改性透明质酸(CA-HA)。使用表面张力、芘荧光探针、动态光散射和Zeta电位方法研究了CA-HA在水溶液表面和溶液中的聚集性质。紫外光照射后,CA-HA在250~325 nm处的紫外吸收未出现明显蓝移,说明CA-HA能够抑制CA接枝基团的光异构化,使CA接枝基团保持反式构型。除了CA接枝基团的荧光发射峰外,CA-HA在350~500 nm处还出现了CA接枝基团二聚体的荧光发射峰。随着质量浓度增大,CA-HA能够产生明显增强的聚集诱导荧光。同时,CA-HA乳液在紫外线B(UVB)波段(275~320 nm)具有良好的防晒性能。

A hydrophobically modified hyaluronic acid(CA-HA)was prepared by the esterification reaction of the carboxyl group of cinnamic acid(CA)with the hydroxyl group of hyaluronic acid(HA).The maximum solubility of CA-HA in the aqueous solution was determined to be 4.0 mg/mL by the UV standard curve method.Surface tension,fluorescence,dynamic light scattering and Zeta potential were used to study the aggregation properties of CA-HA on the surface of an aqueous solution and in the solution.CA-HA can reduce the surface tension of the aqueous solution to 32 mN/m,forming aggregates with a particle size of 236 nm and a Zeta potential of−44.8 mV in aqueous solution.After UV irradiation,compared to CA alone,the UV absorbance of CA-HA at 250—325 nm doesn't show a significant blue shift,which suggests that the side chain of HA can inhibit the photoisomerization of CA probably through a steric effect.In addition to the fluorescence of monomeric CA,CA-HA exhibits fluorescence emission over a spectral range of 350—500 nm,characteristic of dimeric CAs.A significantly enhanced aggregation-induced fluorescence emission is observed when the concentration of CA-HA increases.A CA-HA emulsion is shown to have good sunscreen performance in the UVB band(275—320 nm).