Tambunlertchai Supreeda, Srisang Siriwan, Nasongkla Norased
Department of Biomedical Engineering, Faculty of Engineering, Mahidol University, Nakorn Pathom, Thailand.
J Mater Sci Mater Med. 2017 Jun;28(6):90. doi: 10.1007/s10856-017-5899-2. Epub 2017 May 9.
Layer-by-layer (LbL) dip coating, accompanying with the use of micelle structure, allows hydrophobic molecules to be coated on medical devices' surface via hydrogen bonding interaction. In addition, micelle structure also allows control release of encapsulated compound. In this research, we investigated methods to coat and maximize the amount of chlorhexidine (CHX) on silicone surface through LbL dip coating method utilizing hydrogen bonding interaction between PEG on micelle corona and PAA. The number of coated cycles was varied in the process and 90 coating cycles provided the maximum amount of CHX loaded onto the surface. In addition, pre-coating the surface with PAA enhanced the amount of coated CHX by 20%. Scanning electron microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) were used to validate and characterize the coating. For control release aspect, the coated film tended to disrupt at physiological condition; hence chemical crosslinking was performed to minimize the disruption and maximize the release time. Chemical crosslinking at pH 2.5 and 4.5 were performed in the process. It was found that chemical crosslinking could help extend the release period up to 18 days. This was significantly longer when compared to the non-crosslinking silicone tube that could only prolong the release for 5 days. In addition, chemical crosslinking at pH 2.5 gave higher and better initial burst release, release period and antimicrobial properties than that of pH 4.5 or the normal used pH for chemical crosslinking process.
层层（LbL）浸涂法，结合胶束结构的使用，可使疏水分子通过氢键相互作用包覆在医疗设备表面。此外，胶束结构还能实现被包封化合物的控释。在本研究中，我们研究了利用胶束冠层上的聚乙二醇（PEG）与聚丙烯酸（PAA）之间的氢键相互作用，通过层层浸涂法在硅胶表面包覆洗必泰（CHX）并使其负载量最大化的方法。在该过程中改变包覆循环次数，90次包覆循环使表面负载的CHX量达到最大。此外，用PAA预涂覆表面可使CHX的包覆量提高20%。使用扫描电子显微镜（SEM）和傅里叶变换红外光谱（FTIR）对涂层进行验证和表征。对于控释方面，涂层薄膜在生理条件下容易破裂；因此进行化学交联以尽量减少破裂并延长释放时间。在该过程中进行了pH 2.5和4.5条件下的化学交联。结果发现，化学交联可将释放期延长至18天。与只能将释放时间延长5天的未交联硅胶管相比，这显著更长。此外，pH 2.5条件下的化学交联比pH 4.5或化学交联过程常用的pH条件具有更高、更好的初始突释、释放期和抗菌性能。
