Abstract
Magnetic micro-sized mesoporous silica particles were used for the preparation of a gated material able to release an entrapped cargo in the presence of an azo-reducing agent and, to some extent, at acidic pH. The magnetic mesoporous microparticles were loaded with safranin O and the external surface was functionalized with an azo derivative 1 (bearing a carbamate linkage) yielding solid S1. Aqueous suspensions of S1 at pH 7.4 showed negligible safranin O release due to the presence of the bulky azo derivative attached onto the external surface of the inorganic scaffold. However, in the presence of sodium dithionite (azoreductive agent), a remarkable safranin O delivery was observed. At acidic pH, a certain safranin O release from S1 was also found. The pH-triggered safranin O delivery was ascribed to the acid-induced hydrolysis of the carbamate moiety that linked the bulky azo derivatives onto the mesoporous inorganic magnetic support. The controlled release behavior of S1 was also tested using a model that simulated the gastro intestinal tract.
Highlights
In recent years, the blending of coordination, molecular, supramolecular and biomolecular chemistry concepts with porous materials has led to the development of smart functional gated materials with multiple applications in different scientific and technological fields [1]
Bearing in mind our interest in the development of silica-based gated materials for controlled release applications [22,23,24,25,26,27,28,29], we report the preparation of capped a micro-sized silica mesoporous solid containing magnetic nanoparticles (S1) as a suitable carrier to release an entrapped cargo in colon
Magnetic nanoparticles (MNPs) coated with oleic acid were prepared by a co-precipitation procedure that used a mixture of FeCl3 and FeCl2 and ammonium hydroxide [30]
Summary
The blending of coordination, molecular, supramolecular and biomolecular chemistry concepts with porous materials has led to the development of smart functional gated materials with multiple applications in different scientific and technological fields [1] These hybrid materials are mainly composed by two subunits: (i) an inorganic porous support for cargo loading; and (ii) certain molecules acting as “molecular gates” for controlled cargo release upon the application of external stimuli [2]. Dealing with controlled drug release, the preparation of carriers able to deliver certain drugs at-will and on the site of action, minimizing secondary effects, is a benchmark in the treatment of different diseases [14]
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