Development of encapsulated antimicrobial additives to extend bioactivity
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The development of silica microspheres that contain immobilized copper has led to the application of antibacterial or antifungal paint additive that is effective, yet safe to human beings. However, the fast release of copper when the microspheres suspended in water-based solvent remains problematic as it reduces the useful lifetime of their applications, such as paint additives. A slow and controlled release is often preferred to achieve efficient and prolonged antimicrobial effect. In this study, the release of copper from acrylic-coating can be controlled by varying the silica to copper ratio and by forming the microspheres with complex pore properties. The goal of the research was to develop antimicrobial additives for paint. The additives were synthesis by modified silica-copper microparticles with 3-glycidyloxypropyltrimethoxysilane (GLYMO) and 3-Aminopropyl)triethoxysilane (APTES). This work involvs the incorporation of copper (II) in form of copper acetate (Cu(CO2CH3)2) to silica microparticles by using tetraethoxysilane (TEOS) as a precursor. Copper loading capacity and copper adherence on silica surface were enhanced by addition of GLYMO and APTES. The objective is to produce Cu/SiO2 microspheres to be mixed in antimicrobial paint that can inhibit growth of Escherichia coli (E.coli) and Penicillium funiculosum (P. funiculosum). The effects in the addition of GLYMO/APTES to TEOS solution were studied. The sol-gel formation with acid catalysts was used in combination with a spray dryer to obtain Cu/SiO2 microspheres. The morphology of Cu/SiO2 microspheres was observed using Field Emissive Scanning Electron Microscope (FE-SEM) to determine the particle size and particles size distributions. Energy-dispersive spectrometry (EDS) and X-ray Fluorescence (XRF) used an elemental analysis method to identify and quantify all compounds. The specific functional groups of modified surfaces was confirmed by Fourier Transform Infrared Spectroscopy (FTIR). Thermogravimetric Analysis (TGA) was used to measure percent weight loss to determine the organosilane content in Cu/SiO2 microspheres. ImageJ program was used to determine the area of microorganism growth on the paints surface, which was used to calculate the inhibition rate. The higher proportion of additives present in paints, the higher the antimicrobial activities.
负载固定化铜的二氧化硅微球的研发，催生了高效且对人体安全的抗菌/抗真菌涂料添加剂的应用。然而，当微球分散于水基溶剂中时，铜的快速释放仍是一个亟待解决的问题——该问题会缩短此类添加剂（如涂料添加剂）的应用寿命。为实现高效且持久的抗菌效果，通常需要实现铜的缓慢可控释放。本研究通过调控二氧化硅与铜的比例，并制备具有复杂孔隙结构的微球，实现了丙烯酸涂料中铜释放行为的可控调节。本研究的目标是开发用于涂料的抗菌添加剂。本研究采用3-缩水甘油醚氧基丙基三甲氧基硅烷（3-glycidyloxypropyltrimethoxysilane, GLYMO）与3-氨丙基三乙氧基硅烷（3-Aminopropyltriethoxysilane, APTES）对二氧化硅-铜微粒进行改性，以此制备目标添加剂。本研究以四乙氧基硅烷（tetraethoxysilane, TEOS）为前驱体，将乙酸铜（copper acetate, Cu(CO₂CH₃)₂）形式的二价铜负载至二氧化硅微粒中。添加GLYMO与APTES可提升铜在二氧化硅表面的负载量与附着稳定性。本研究的核心目标是制备Cu/SiO₂微球，将其混入抗菌涂料中，以抑制大肠杆菌（Escherichia coli, E. coli）和绳状青霉菌（Penicillium funiculosum, P. funiculosum）的生长。研究了向TEOS溶液中添加GLYMO与APTES所产生的影响。本研究采用酸催化溶胶-凝胶法结合喷雾干燥工艺制备Cu/SiO₂微球。采用场发射扫描电子显微镜（Field Emissive Scanning Electron Microscope, FE-SEM）观测Cu/SiO₂微球的形貌，以测定其粒径与粒径分布。采用能量色散X射线光谱（Energy-dispersive spectrometry, EDS）与X射线荧光光谱（X-ray Fluorescence, XRF）这两种元素分析方法，对样品中的所有组分进行定性与定量检测。通过傅里叶变换红外光谱（Fourier Transform Infrared Spectroscopy, FTIR）对改性表面的特征官能团进行了表征确认。采用热重分析（Thermogravimetric Analysis, TGA）测试样品的质量损失率，以此计算Cu/SiO₂微球中的有机硅烷含量。采用ImageJ软件测定涂料表面微生物生长的面积，以此计算抗菌抑制率。涂料中添加剂的比例越高，其抗菌活性越强。
