A rapid and facile synthesis route to the monodisperse spherical MCM-48 mesoporous silica nanoparticles (MSN) with cubic Ia3̅d mesostructure is developed based on the modified Stöber method. The phase domain of MCM-48-type MSNs can be extended by controlling the stirring rate and molar ratios of silica source and surfactant. The formation of monodispersed spherical MCM-48-type MSNs is obtained using triblock copolymer Pluronic F127 as a particle size designer. The average size of monodisperse spherical MSN can be controlled within the range of 70−500 nm depending on the amount of F127. Moreover, the pore diameter of MSNs can be precisely controllable in pore diameters from 2.3 to 3.3 nm using different alkyl chain surfactants and simple posthydrothermal treatment. An investigation of MCM-48-type MSN materials using powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and nitrogen physisorption clearly reveals that MSNs show high specific surface area, high pore volumes, controllable morphological aspects, and tunable pore diameters. The MCM-48-type MSNs thus obtained are demonstrated as a good hard template for the preparation of other mesoporous nanoparticles, such as mesoporous metal oxides. The present discovery of the extended synthesis conditions and the binary surfactant system in MCM-48 synthesis offers reproducible and facile synthesis of the monodisperse spherical MCM-48 mesoporous silica nanoparticles with precise structural control, and thus has vast prospects for future applications of ultrafine mesostructured nanoparticle materials.

Photocatalytic formation of hydrocarbons using solar energy via artificial photosynthesis is a highly desirable renewable-energy source for replacing conventional fossil fuels. Using an l-cysteine-based hydrothermal process, here we synthesize a carbon-doped SnS2 (SnS2-C) metal dichalcogenide nanostructure, which exhibits a highly active and selective photocatalytic conversion of CO2 to hydrocarbons under visible-light. The interstitial carbon doping induced microstrain in the SnS2 lattice, resulting in different photophysical properties as compared with undoped SnS2. This SnS2-C photocatalyst significantly enhances the CO2 reduction activity under visible light, attaining a photochemical quantum efficiency of above 0.7%. The SnS2-C photocatalyst represents an important contribution towards high quantum efficiency artificial photosynthesis based on gas phase photocatalytic CO2 reduction under visible light, where the in situ carbon-doped SnS2 nanostructure improves the stability and the light harvesting and charge separation efficiency, and significantly enhances the photocatalytic activity.

A structurally ordered, CMK-1 type mesoporous carbon nanoparticle (MCN) material was successfully synthesized by using a MCM-48 type mesoporous silica nanoparticle as template. The structure of MCN was analyzed by a series of different techniques, including the scanning and transmission electron microscopy, powder X-ray diffraction, and N2 sorption analysis. To the best of our knowledge, no study has been reported prior to our investigation on the utilization of these structurally ordered mesoporous carbon nanoparticles for the delivery of membrane impermeable chemical agents inside of eukaryotic cells. The cellular uptake efficiency and biocompatibility of MCN with human cervical cancer cells (HeLa) were investigated. Our results show that the inhibitory concentration (IC50) value of MCN is very high (>50 μg/mL per million cells) indicating that MCN is fairly biocompatible in vitro. Also, a membrane impermeable fluorescence dye, Fura-2, was loaded to the mesoporous matrix of MCN. We demonstrated that the MCN material could indeed serve as a transmembrane carrier for delivering Fura-2 through the cell membrane to release these molecules inside of live HeLa cells. We envision that further developments of this MCN material will lead to a new generation of nanodevices for transmembrane delivery and intracellular release applications. Disciplines Chemistry CommentsReprinted (adapted) with permission from Nano Letters 8 (2008) Received July 6, 2008; Revised Manuscript Received September 17, 2008 ABSTRACT A structurally ordered, CMK-1 type mesoporous carbon nanoparticle (MCN) material was successfully synthesized by using a MCM-48 type mesoporous silica nanoparticle as template. The structure of MCN was analyzed by a series of different techniques, including the scanning and transmission electron microscopy, powder X-ray diffraction, and N 2 sorption analysis. To the best of our knowledge, no study has been reported prior to our investigation on the utilization of these structurally ordered mesoporous carbon nanoparticles for the delivery of membrane impermeable chemical agents inside of eukaryotic cells. The cellular uptake efficiency and biocompatibility of MCN with human cervical cancer cells (HeLa) were investigated. Our results show that the inhibitory concentration (IC 50 ) value of MCN is very high (>50 µg/mL per million cells) indicating that MCN is fairly biocompatible in vitro. Also, a membrane impermeable fluorescence dye, Fura-2, was loaded to the mesoporous matrix of MCN. We demonstrated that the MCN material could indeed serve as a transmembrane carrier for delivering Fura-2 through the cell membrane to release these molecules inside of live HeLa cells. We envision that further developments of this MCN material will lead to a new generation of nanodevices for transmembrane delivery and intracellular release applications.