A rapid synthesis of magnetic-core mesoporous silica-shell nanostructures -as potential theranostic agents, by means of microwave irradiation and the atrane method

Abstract

Nowadays, the interest in the design of particles that combine therapy and diagnosis simultaneously to obtain a theranostic material has increased. One of the mostly used materials for MRI diagnosis is iron oxide, where superparamagnetic iron oxide (SPIONs) are a noteworthy candidate. These particles are of high interest due to their broad applications, such as contrast agents, magnetic separation, and hyperthermia, among others. One of their major problems is to maintain superparamagnetism while having the highest magnetization-to-particle ratio. In this work, microwave-assisted synthesis of clusters formed by SPIONs has been investigated. This synthesis strategy has allowed for a significant reduction in the time and energy required to obtain SPION clusters. Also, the magnetization-to-particle ratio has been increased in comparison with single SPIONs. Subsequently, the clusters were coated with amorphous silica using Stöber method, followed by mesoporous (MS) silica using the atrane method, which offers a high and conformal coating homogeneity over the clusters. Surfactant extraction was done using a simple mixture of water, ethanol, and sodium chloride -avoiding the use of other organic solvents. Finally, as a proof of concept, the loading and release of a model molecule were studied to confirm that the SPIONs-NCs@MS presented in this work have a great potential as a theranostic agent.