Internally bridged nanosilica for loadings and release of sparsely soluble compounds.

The engineering of a new monodisperse colloid with a sea urchin-like structure with a large complex internal structure is reported, in which silica surfaces are bridged by an aromatic organic cross-linker to serve as a nanocarrier host for drugs such as doxorubicin (DOX) against breast cancer cells. While dendritic fibrous nanosilica (DFNS) was employed and we do not observe a dendritic structure, these particles are referred to as sea urchin-like nanostructured silica (SNS). Since the structure of SNS consists of many silica fibrils protruding from the core, similar to the hairs of a sea urchin. For the aromatic structured cross-linker, bis(propyliminomethyl)benzene (b(PIM)B-S or silanated terephtaldehyde) were employed, which are prepared with terephtaldehyde and 3-aminopropyltriethoxy-silane (APTES) through a simple Schiff base reaction. b(PIM)B-S bridges were introduced into SNS under open vessel reflux conditions. SPS refers to the product obtained by incorporating the cross-linker b(PIM)B-S in ultra-small colloidal SNS particles. In-situ incorporation of DOX molecules resulted in SPS-DOX. The pH-responsive SPS nanocomposites were tested as biocompatible nanocarriers for controllable doxorubicin (DOX) delivery. We conclude that SPS is a unique colloid which has promising potential for technological applications such as advanced drug delivery systems, wastewater remediation and as a catalyst for green organic reactions in water.

Hairy Nanocellulose-Based Supramolecular Architectures for Sustained Drug Release.

The engineering of a new type of trifunctional biopolymer-based nanosponges polymerized by cross-linking beta-cyclodextrin ethylene diamine (ßCD-EDA) with bifunctional hairy nanocellulose (BHNC) is reported herein. We refer to the highly cross-linked polymerized BHNC-ßCD-EDA network as BBE. ßCD-EDA and BHNC were cross-linked at various ratios with the help of DMTMM (4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium) as a green activator in deionized water as a solvent, which resulted in different morphological shapes of BBE. Some of these structures were chiral due to cross-linked liquid crystalline structures. A comprehensive characterization study was done to show their unique morphological, structural, and dimensional properties of BBEs. Moreover, to further investigate and to confirm the surface modification of the precursors and final BBE structures, Fourier transform infrared and nuclear magnetic resonance spectroscopy, thermogravimetric analysis, Brunauer-Emmett-Teller analysis, and X-ray diffraction were applied. The hairy nanocellulose particles were considered as the backbone, and the immobilized cyclodextrin cavities can capture doxorubicin, which was used as a model drug molecule via host-guest inclusion complexation. Finally, the obtained BBE networks showed different and sustained drug release profiles and pH responsiveness. BBE biopolymers were tested as biocompatible nanocarriers for controlled release. We realize that these structures are too big for anti-cancer drug delivery by injection or oral intake, but these structures have a high potential to be applied in wound dressing and implants. They could also be used for capturing antibiotics, dyes, and organic compounds from wastewater.

Biotemplated Hollow Mesoporous Silica Particles as Efficient Carriers for Drug Delivery.

We designed three types of hollow-shaped porous silica materials via a three-step biotemplate-directed method: porous hollow silica nanorods, hollow dendritic fibrous nanostructured silica (DFNS), and ultraporous sponge-like DFNS. The first step was making a biotemplate, for which we used cellulose nanocrystals (CNCs), consisting of rod-shaped nanoparticles synthesized by conventional acid hydrolysis of cellulose fibers. In a second step, core-shell samples were prepared using CNC particles as hard template by two procedures. In the first one, core-shell CNC-silica nanoparticles were synthesized by a polycondensation reaction, which exclusively took place at the surface of the CNCs. In the second procedure, a typical synthesis of DFNS was conducted in a bicontinuous microemulsion with the assistance of additives. DFNS was assembled on the surface of the CNCs, giving rise to core-shell CNC-DFNS structures. Finally, all of the silica-coated CNC composites were calcined, during which the CNC was removed from the core and hollow structures were formed. These materials are very lightweight and highly porous. All three structures were tested as nanocarriers for drug delivery and absorbents for dye removal applications. Dye removal results showed that they can adsorb methylene blue efficiently, with ultraporous sponge-like DFNS showing the highest adsorption capacity, followed by hollow DFNS and hollow silica nanorods. Furthermore, breast cancer cells show a lower cell viability when exposed to doxorubicin-loaded hollow silica nanorods compared with control or doxorubicin cultures, suggesting that the loaded nanorod has a greater anticancer effect than free doxorubicin.