Self-assembly of multi-hierarchically structured spongy mesoporous silica particles and mechanism of their formation

International audienceHere we report on self-assembly of novel multi-hierarchically structured meso(nano)porous colloidal silica particles which have cylindrical pores of 4-6 nm, overall size of 10 gm and "cracks" of 50-200 nm. These cracks make particles look like micro-sponges. The particles were prepared through a modified templated sol-gel self-assembly process. The mechanism of assembly of these particles is investigated. Using encapsulated fluorescent dye, we demonstrate that the spongy particles are advantageous to facilitate dye diffusion out of particles. This multi-hierarchically geometry of particles can be used to improve the particle design for multiple applications to control drug release, rate of catalysis, filtration, utilization of particles as hosts for functional molecules (e.g., enzymes), etc. (C) 2016 Elsevier Inc. All rights reserved

Self-assembly of multi-hierarchically structured spongy mesoporous silica particles and mechanism of their formation

International audienceHere we report on self-assembly of novel multi-hierarchically structured meso(nano)porous colloidal silica particles which have cylindrical pores of 4-6 nm, overall size of 10 gm and "cracks" of 50-200 nm. These cracks make particles look like micro-sponges. The particles were prepared through a modified templated sol-gel self-assembly process. The mechanism of assembly of these particles is investigated. Using encapsulated fluorescent dye, we demonstrate that the spongy particles are advantageous to facilitate dye diffusion out of particles. This multi-hierarchically geometry of particles can be used to improve the particle design for multiple applications to control drug release, rate of catalysis, filtration, utilization of particles as hosts for functional molecules (e.g., enzymes), etc. (C) 2016 Elsevier Inc. All rights reserved

Control and formation mechanism of extended nanochannel geometry in colloidal mesoporous silica particles

International audienceA large class of colloidal multi-micron mesoporous silica particles have well-defined cylindrical nanopores, nanochannels which self-assembled in the templated sol-gel process. These particles are of broad interest in photonics, for timed drug release, enzyme stabilization, separation and filtration technologies, catalysis, etc. Although the pore geometry and mechanism of pore formation of such particles has been widely investigated at the nanoscale, their pore geometry and its formation mechanism at a larger (extended) scale is still under debate. The extended geometry of nanochannels is paramount for all aforementioned applications because it defines accessibility of nanochannels, and subsequently, kinetics of interaction of the nanochannel content with the particle surrounding. Here we present both experimental and theoretical investigation of the extended geometry and its formation mechanism in colloidal multi-micron mesoporous silica particles. We demonstrate that disordered (and consequently, well accessible) nanochannels in the initially formed colloidal particles gradually align and form extended self-sealed channels. This knowledge allows to control the percentage of disordered versus self-sealed nanochannels, which defines accessibility of nanochannels in such particles. We further show that the observed aligning the channels is in agreement with theory; it is thermodynamically favored as it decreases the Gibbs free energy of the particles. Besides the practical use of the obtained results, developing a fundamental understanding of the mechanisms of morphogenesis of complex geometry of nanopores will open doors to efficient and controllable synthesis that will, in turn, further fuel the practical utilization of these particles

Control and formation mechanism of extended nanochannel geometry in colloidal mesoporous silica particles

International audienceA large class of colloidal multi-micron mesoporous silica particles have well-defined cylindrical nanopores, nanochannels which self-assembled in the templated sol-gel process. These particles are of broad interest in photonics, for timed drug release, enzyme stabilization, separation and filtration technologies, catalysis, etc. Although the pore geometry and mechanism of pore formation of such particles has been widely investigated at the nanoscale, their pore geometry and its formation mechanism at a larger (extended) scale is still under debate. The extended geometry of nanochannels is paramount for all aforementioned applications because it defines accessibility of nanochannels, and subsequently, kinetics of interaction of the nanochannel content with the particle surrounding. Here we present both experimental and theoretical investigation of the extended geometry and its formation mechanism in colloidal multi-micron mesoporous silica particles. We demonstrate that disordered (and consequently, well accessible) nanochannels in the initially formed colloidal particles gradually align and form extended self-sealed channels. This knowledge allows to control the percentage of disordered versus self-sealed nanochannels, which defines accessibility of nanochannels in such particles. We further show that the observed aligning the channels is in agreement with theory; it is thermodynamically favored as it decreases the Gibbs free energy of the particles. Besides the practical use of the obtained results, developing a fundamental understanding of the mechanisms of morphogenesis of complex geometry of nanopores will open doors to efficient and controllable synthesis that will, in turn, further fuel the practical utilization of these particles