Polytechnic University of Valencia

About: Polytechnic University of Valencia is a education organization based out in Valencia, Spain. It is known for research contribution in the topics: Catalysis & Population. The organization has 16282 authors who have published 40162 publications receiving 850234 citations.

Controlled delivery using oligonucleotide-capped mesoporous silica nanoparticles.

Abstract: The design of delivery systems with “molecular locks” able to selectively release entrapped guests in the presence of target triggers has attracted great attention recently. As an alternative to traditional polymer-based delivery systems, mesoporous silica supports show unique properties such as a large load capacity, biocompatibility, and potential for the development of gated supports for on-command delivery applications. Recently, mesoporous-silica-based systems displaying controlled release have been reported relying on changes in pH, redox potential, and light for uncapping the pores. However, the use of mesoporous silica supports equipped with gatelike scaffoldings is still an incipient area of research. In particular, despite some recent reported gated mesoporous silica supports that can be uncapped using antigens or enzymes, there is an almost complete lack of mesoporous-silica-based devices designed to trigger cargo release involving biomolecules. Within this context, our interest in the development of gated materials motivated us to explore the possible design of new “bio-gates” able to respond selectively to “key” molecules. We focused our attention on the use of nucleotides. The proposed paradigm is represented in Scheme 1. In this work nanoparticles (ca. 100 nm) of mesoporous MCM-41 have been selected as the inorganic scaffold. The MCM-41 support is first loaded with a suitable guest (fluorescein), and then the external surface is functionalized with 3-aminopropyltriethoxysilane (APTS) to give the solid S1. Aminopropyl groups are partially charged at neutral pH in water and will interact with negatively charged oligonucleotides, resulting in the closing of the mesopores. The opening protocol will be expected to occur by a highly effective displacement reaction in the presence a target complementary strand; this will result in hybridization of the two oligonucleotides, the uncapping of the pores, and release of the entrapped cargo. The mesoporous solid S1 containing fluorescein in the pore voids and functionalized on the external surface with APTS groups was characterized following standard procedures (see the Supporting Information). The powder X-ray diffraction (XRD) pattern of siliceous MCM-41 nanoparticles as synthesized (Figure 1, curve a) shows four low-angle reflections typical of a hexagonal array which can be indexed as (100), (110), (200), and (210) Bragg peaks. A significant displacement of the (100) peak in the XRD pattern of the MCM-41 calcined nanoparticles is evident in curve b. Finally, curve c corresponds to the XRD pattern of S1. The (100), (110), and (200) peaks are clearly observed strongly suggesting that the dye loading and further functionalization with Scheme 1. Representation of the gated material S1 functionalized with 3-aminopropyltriethoxysilane and capped with a single-stranded oligonucleotide (O1). The delivery of the entrapped guest (fluorescein) is selectively accomplished in the presence of the complementary oligonucleotide (O2). The sequence of the oligonucleotides O1 and O2 is shown.