Hidrojen bağlı poly(2-etil-2-oksazolin) ve tanik asit tabaka-tabaka yapıları ve bu yapıların biyolojik uygulamaları

The biological applications involving antibacterial coatings and controlled release systems require careful design and realization of the material system. Layer-by-layer (LbL) assembly of interacting molecules is a versatile method to prepare functional coatings. The formation of such coatings on sacrificial 3-dimensional templates allows the preparation of hollow capsules which show significant potential as controlled release systems. In this thesis study, pH-responsive hydrogen-bonded (H-bonded) 2-dimensional (films) and 3-dimensional (hollow capsules) LbL assemblies of poly(2-ethyl-2-oxazoline) (PEOX) and Tannic Acid (TA) have been prepared, investigated and their biological applications as antibacterial coatings and controlled release systems have been demonstrated. Contact-killing, pH-responsive antibacterial coatings, especially for surgical devices and implants, were realized by H-bonded LbL assembly of PEOX stabilized silver nanoparticles (AgNPs) (~10-20 nm in diameter) as H-acceptor and TA as H-donor. The effect of PEOX molar mass (5,000 to 500,000 g/mol) on the stabilization of AgNPs and the antibacterial efficacy of the resulting coatings has been investigated. The coatings were stable below pH 8.5 and disintegrated above pH 8.5. JIS Z 2801 antibacterial tests demonstrated the antibacterial efficacy of the coatings through contact killing against both gram negative and gram-positive bacteria. The coatings on titanium substrates remained stable and retained their antibacterial efficacy at pH 7.4 in phosphate buffered saline up to 3 months. Hollow microcapsules (5-8 m in diameter) formed of 8 bilayers PEOX/TA LbL films were prepared by coating CaCO3 microparticle templates followed by the dissolution of the microparticles. Rhodamine 6G was used as positively charged model cargo to evaluate the loading and release properties of the hollow capsules for potential controlled release applications. Rhodamine 6G loaded capsules exhibited pH-dependent release which increased with pH towards physiological pH of 7.4. The increase in the amount of released Rhodamine 6G molecules with increasing pH was attributed to the increased permeability of the capsules as a result of the decreasing number of H-bonds due to ionization of TA. Such H-bonded capsules have a high potential to be used as pH-responsive micro-carriers in drug delivery applications.