Abstract
Among the different types of nanoparticles used in biomedical applications, Fe nanoparticles and mesoporous siliceous materials have been extensively investigated because of their possible theranostic applications. Here, we present hollow-shell mesoporous silica nanoparticles that encapsulate iron oxide and that are prepared using a drug-structure-directing agent concept (DSDA), composed of the model drug tryptophan modified by carbon aliphatic hydrocarbon chains. The modified tryptophan can behave as an organic template that allows directing the hollow-shell mesoporous silica framework, as a result of its micellisation and subsequent assembly of the silica around it. The one-pot synthesis procedure facilitates the incorporation of hydrophobically stabilised iron oxide nanoparticles into the hollow internal silica cavities, with the model drug tryptophan in the shell pores, thus enabling the incorporation of different functionalities into the all-in-one nanoparticles named mesoporous silica nanoparticles containing magnetic iron oxide (Fe3O4@MSNs). Additionally, the drug loading capability and the release of tryptophan from the silica nanoparticles were examined, as well as the cytostaticity and cytotoxicity of the Fe3O4@MSNs in different colon cancer cell lines. The results indicate that Fe3O4@MSNs have great potential for drug loading and drug delivery into specific target cells, thereby overcoming the limitations associated with conventional drug formulations, which are unable to selectively reach the sites of interest.
Highlights
The optimal stabiliser ligands for the appropriate incorporation of Fe3 O4 NPs into the h-mesoporous silica nanoparticles (MSNs) were determined according to the morphological characteristics of the magnetic Fe3 O4 @MSNs observed from scanning electron microscopy (SEM) images, as further discussed below
Hollow-shell MSNs with a raspberry-like rough surface and iron oxide magnetite inside have been successfully synthesised through an oil-in-water emulsion method based on the drug-structure-directing agent concept (DSDA) concept
The DSDA is composed of the model drug Ltryptophan modified with decanoic aliphatic hydrocarbon chains, which are responsible for the structure of the hollow-shell MSNs (h-MSNs) and impart intrinsic pharmacological activity to the h-MSNs
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Nanoparticles (NPs) have been investigated for biomedical applications because their versatility enables the development of smart materials that can target specific tissues and because of their potential as drug vehicles. The current trends of employing NPs in medicine are focused on the development of novel strategies for the treatment and diagnosis of several diseases [9]. NPs for biomedical applications are obtained via different strategies, including organic systems (micelles, liposomes, and polymers, among others) [10,11], inorganic-based NPs (silica, iron oxides, carbon nanotubes, etc.) [12,13,14], and organic–inorganic systems [15]
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