Ian Wark Research Institute, University of South Australia, Mawson Lakes Boulevard, Australia.
J Biomater Appl. 2013 Aug;28(2):163-74. doi: 10.1177/0885328212441846. Epub 2012 Mar 28.
Naturally available and biocompatible materials are potential substitutes for synthetic mesoporous materials as suitable drug carriers for the development of cost-effective drug delivery systems. This work investigates the application of a porous silica material derived from diatoms, also known as diatomaceous earth. The aim is to explore the surface functionalization of diatom microcapsules and their impact on the drug loading and release characteristics of water-insoluble drugs. Indomethacin was used as the model for poorly soluble drug. The surface modification on diatoms was performed with two organosilanes; 3-aminopropyltriethoxy silane and N-(3-(trimethoxysilyl) propyl) ethylene diamine and phosphonic acids (2-carboxyethyl-phosphonic acid and 16-phosphono-hexadecanoic acid) providing organic surface hydrophilic and hydrophobic properties. Extensive characterizations using scanning electron microscopy, X-ray photoelectron spectroscopy and differential scanning calorimetry was performed to confirm covalent grafting of monolayer aminosilane and phosphonic acid on the diatom surfaces. Differences in loading capacity of diatoms (15-24%) and release time (6-15 days) were observed which is due to the presence of different functional groups on the surface. It was found that 2-carboxyethyl-phosphonic acid, 3-aminopropyltriethoxy silane and N-(3-(trimethoxysilyl) propyl) ethylene diamine render diatom surfaces hydrophilic, due to polar carboxyl functional group (COOH) and active amine species (NH and NH2) that favor drug adsorption; better encapsulation efficiency and prolonged release of drugs, over the hydrophobic surface created by 16-phosphono-hexadecanoic acid. This work demonstrates diatom porous silica as a promising drug carrier, with possibility to further improve their performances by tailoring their surface functionalities to achieve the required drug loading and release characteristics for different therapeutic conditions.
天然存在且生物相容的材料可作为合成介孔材料的替代品，用作开发具有成本效益的药物输送系统的合适药物载体。本工作研究了一种源自硅藻的多孔硅材料的应用，也称为硅藻土。目的是探索硅藻微胶囊的表面功能化及其对水不溶性药物的药物负载和释放特性的影响。将吲哚美辛用作难溶性药物的模型。使用两种有机硅烷（3-氨丙基三乙氧基硅烷和 N-（3-（三甲氧基硅基）丙基）乙二胺）和膦酸（2-羧乙基膦酸和 16-膦基十六烷酸）对硅藻进行表面改性，提供有机表面亲水性和疏水性。使用扫描电子显微镜、X 射线光电子能谱和差示扫描量热法进行了广泛的表征，以确认单层氨丙基硅烷和膦酸在硅藻表面的共价接枝。观察到硅藻的负载能力（15-24%）和释放时间（6-15 天）存在差异，这是由于表面存在不同的官能团。结果发现，由于存在极性羧基官能团（COOH）和活性胺类（NH 和 NH2），2-羧乙基膦酸、3-氨丙基三乙氧基硅烷和 N-（3-（三甲氧基硅基）丙基）乙二胺使硅藻表面亲水，有利于药物吸附；与由 16-膦基十六烷酸形成的疏水性表面相比，药物的包封效率更高，释放时间更长。这项工作证明了硅藻多孔硅作为一种有前途的药物载体，通过调整其表面功能来进一步提高其性能，以实现不同治疗条件下所需的药物负载和释放特性。
