Abstract
The aim of this study is to determine the efficiency of loading and release of several zwitterionic, neutral, anionic and cationic dyes into/from mesoporous nanoparticles to find the optimum loading and release conditions for their application in detection protocols. The loading is carried out for MCM-41 type silica supports suspended in phosphate-buffered saline (PBS) buffer (pH 7.4) or in acetonitrile, involving the dyes (rhodamine B chloride, rhodamine 101 chloride, rhodamine 101 perchlorate, rhodamine 101 inner salt, meso-(4-hydroxyphenyl)-boron–dipyrromethene (BODIPY), sulforhodamine B sodium salt and fluorescein 27). As a general trend, rhodamine-based dyes are loaded with higher efficiency, when compared with BODIPY and fluorescein dyes. Between the rhodamine-based dyes, their charge and the solvent in which the loading process is carried out play important roles for the amount of cargo that can be loaded into the materials. The delivery experiments carried out in PBS buffer at pH 7.4 reveal for all the materials that anionic dyes are more efficiently released compared to their neutral or cationic counterparts. The overall best performance is achieved with the negatively charged sulforhodamine B dye in acetonitrile. This material also shows a high delivery degree in PBS buffer.
Highlights
The ability to control the release of cargo from porous materials has been largely associated with drug delivery and widely used in biomedical applications [1]
The structure of the mesoporous silica nanoparticles (MSN) prepared was confirmed by powder X-ray diffraction (PXRD), transmission electron microscopy and N2 adsorption–desorption studies
The Powder X-ray diffraction (PXRD) of nanoparticulated siliceous MCM-41 as-synthesised shows the typical low-angle reflections that can be attributed to a hexagonal array, denoted as (100), (110) and (200)
Summary
The ability to control the release of cargo from porous materials has been largely associated with drug delivery and widely used in biomedical applications [1]. In the last years the scope of this technology has been expanded toward applications in a variety of sectors such as agriculture [3,4], photovoltaic cells [5] external coatings [6] or personal care and cosmetics [7], employing as nanoparticles drug carriers (NPs) of organic [8,9,10] or inorganic [11] nature Among these materials, microporous and mesoporous materials, due to their chemical inertness, homogeneous porosity and large internal surface area, have attracted considerable research interest for applications on the fields of drug delivery [12,13,14], catalysis [15,16,17], filtration and separation [18,19], gas adsorption [20,21] and storage [22,23], enzyme immobilisation [24,25], biomedical tissue regeneration [26,27], environmental remediation [28,29,30], chemical/biochemical sensing [31,32,33] and theranostics [34,35] mostly as nano- or microparticles, and in core/shell formats or in combination with other properties such as magnetic ones [36,37].
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