TiO_2/SiO_2复合中空微球的选择性改性与药物缓释性能研究

以聚合物微球为模板,通过溶胶-凝胶法制备了TiO2/SiO2复合中空微球,并分别采用硬脂酸和无机磷酸对内层二氧化钛进行了疏水和亲水改性.扫描电镜(SEM)和氮气吸附-脱附结果表明中空微球具有完整的球形空腔和多孔的壳层孔道结构.傅立叶红外光谱(FTIR)证实了内部疏水及亲水改性层的存在.以布洛芬药物为对象,采用热重分析(TGA)和高效液相色谱(HPLC)考察了不同改性对复合中空微球的载药量及缓释性能的影响.研究结果表明,由于存在疏水作用,硬脂酸改性的中空微球载药量(189.8mg/g)高于未改性中空微球(177.5mg/g),且药物释放速率明显减慢,53h内药物释放率仅为55%;与此相反,无机磷酸亲水改性的中空微球载药量减小(为153.0mg/g),且释放速率提高,10h内释放了将近80%的药物.因此,采用不同的改性基团可以对复合中空微球的药物释放速率进行有效地调控.

Selective Modification and Application for Controlled Release of TiO_2/SiO_2 Composite Hollow Spheres

The composite TiO₂/SiO₂ hollow spheres (CHSs) were successfully prepared via sol-gel process using carboxyl-functionalized polystyrene spheres as templates. Then the titania layer was selectively modified with stearic acid and phosphate, forming hydrophobic and hydrophilic interior, respectively. Their hollow and porous structures were confirmed by scanning electron microscope (SEM) and N₂ sorption analysis. Fourier transform infrared (FT-IR) spectra indicate that the interaction between the modifiers and the surface of titania is not physical adsorption but chemical combination. Using ibuprofen (IBU) as a model drug, the investigation of drug loading amounts and release rates shows that they can be regulated by suitable modification. Compare with the unmodified system, the stearic acid modified CHSs exhibit higher drug loading amount and lower release rate due to the hydrophobic effect. The IBU loading amount reaches 189.8mg/g and only about 55% of IBU is released within 53h. However, the phosphate modified CHSs exhibit relatively low drug loading amount (153.0mg/g) and high release rate, probably associated to the hydrophilic shells and charge repulsion. Its release percentage reaches nearly 80% within 10h. Therefore, the produced CHSs have potential application in the sustained drug delivery.