Tailoring morphological and interfacial properties of diatom silica microparticles for drug delivery applications

• Published in: Advanced powder technology : the international journal of the Society of Powder Technology, Japan Japan, 2013-07, Vol.24 (4), p.757-763
• Main Authors: Bariana, Manpreet, Aw, Moom Sinn, Losic, Dusan
• Format: Article
• Language: English
• Subjects: Bacillariophyceae; Diatomaceous earth; Drug delivery; Drug delivery systems; Drugs; Interfacial properties; Microparticles; Morphology; Particle size; Porous materials; Silicon dioxide; Surface modifications; Sustained release
• ISSN: 0921-8831; 1568-5527
• DOI: 10.1016/j.apt.2013.03.015

•The use of natural porous silica from diatoms for drug delivery is described.•Their surface modification with silanes and phosphonic acid is demonstrated.•The drug loading and release of two model drugs was successfully demonstrated.•The chemical modification and particle size have influence on drug release.•Diatom silica is promising new biomaterial for pharmaceutical applications. Diatomaceous earth (DE), naturally available silica, originated from fossilized diatoms has been explored for use in drug delivery applications as a potential substitute for synthetic silica materials. The aim of this study is to explore the influence of particle size, morphology and surface modifications of diatom silica microparticles on their drug release properties. Raw DE materials was purified and prepared to obtain high purity DE silica porous particles with different size and morphologies. Comparative scanning electron microscope and particle characterization confirmed their particle size including irregularly shaped silica particles (size 0.1–1μm, classified as “fine”), mixed fractions (size 1–10μm, classified as “mixture”) and pure, unbroken DE structures (size 10–15μm, classified as “entire”). Surface modification of DE with silanes and phosphonic acids was performed using standard silanization and phosphonation process to obtain surface with hydrophilic and hydrophobic properties. Water insoluble (indomethacin) and water soluble (gentamicin) drugs were loaded in DE particles to study their drug release performances. In vitro drug release studies were performed over 1–4weeks, to examine the impact of the particle size and hydrophilic/hydrophobic functional groups. The release studies showed a biphasic pattern, comprising an initial burst release for 6h, followed by near-zero order sustained release. This study demonstrates the potential of silica DE particles as a natural carrier for water soluble and insoluble drugs with release controlled by their morphological and interfacial properties.