Novel mesoporous silica nanoparticles of peculiar shapes were synthesized, from which hierarchically porous silica coatings were fabricated on glass substrates via layer-by-layer (LbL) assembly, followed by calcination. These porous silica coatings were highly transparent and superhydrophilic. The maximum transmittance reached as high as 94%, whereas that of the glass substrate is 91%. The time for a droplet to spread lower than 5 degrees decreased to as short as 0.25 s. After the coating surface was treated with a low surface energy material, the surface became superhydrophobic (water contract angle >150 degrees) with a very low sliding angle of <1 degree. Compared with MCM-41-type mesoporous silica nanoparticles, the coatings fabricated using the novel mesoporous silica nanoparticles possess much better self-cleaning property. We used scanning (SEM) and transmission (TEM) electron microscopy to observe the morphology and structure of nanoparticles and surfaces. Transmission spectra and their change with time were characterized by UV-vis spectrophotometer. We studied the surface wettability by a contact angle/interface system. The influence of mesopores on the transmittance and wetting properties of coatings was discussed on the basis of experimental observations.

Over the past few years, silica‐based nanotheranostics have demonstrated their great potential for nano/biomedical applications. However, the uncontrollable and difficult degradability of their pure silica framework and long‐time in vivo retention still cause severe and unpredictable toxicity risks. Therefore, it is highly desirable to design and synthesize materials with safer framework structures and compositions. To this aim, the introduction of disulfide bonds into the silica framework can not only maintain high stability in physiological conditions, but also achieve a stimuli‐responsive biodegradation triggered by intracellular reducing microenvironment in living cells, especially in cancer cells. Once nanotheranostics with disulfide (i.e., thioether)‐bridged silsesquioxane framework are taken up by tumor cells via passive or active targeting, the disulfide bonds in the hybrid silica matrix can be cleaved by a high concentration of intracellular glutathione, enabling redox‐triggered biodegradation of the nanosystems for both concomitant release of the loaded therapeutic cargo and in vivo clearance. It is envisioned that such hybrid materials comprised of disulfide‐bridged silsesquioxane frameworks can become promising responsive and biodegradable nanotheranostics. This review summarizes the recent advances in the synthesis of hybrid organosilicas with disulfide‐bridged silsesquioxane frameworks, and discuss their redox‐triggered biodegradation behaviors combined with their biocompatibility and nanobiomedical applications.

Silica-titania core-shell nanoparticles of 30, 40, 50, 55, 75, and 110 nm were prepared from tetraethyl orthosilicate (TEOS) and tetraisopropyl titanate (TIPT). After calcination, the amorphous titania shell transformed into anatase nanoparticles, and the silica-titania core-shell nanoparticles became raspberry-like nanoparticles. These nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and UV-vis spectroscopy. Hierarchically structured antireflective and self-cleaning particulate coatings were fabricated on glass substrates via layer-by-layer (LbL) assembly using silica-titania core-shell nanoparticles and silica nanoparticles as building blocks followed by calcination. The maximum transmittance of coated glass substrates reached as high as ca. 97%, while that of the glass substrates is only ca. 91%. The morphologies of the coatings were observed by SEM and atom force microscopy (AFM). Such hierarchically structured raspberry-like SiO2-TiO2 nanoparticle coatings had superhydrophilic and antifogging properties. The coatings also showed photocatalytic activity toward organic pollutants and thus a self-cleaning property.

Silica coatings with hierarchical structures were prepared on glass substrates via layer-by-layer assembly using hierarchically mesoporous silica nanoparticles as building block. These coatings demonstrated excellent superhydrophilic properties. After hydrophobic modification, the obtained coatings exhibited hydrophobic properties in the measurements of water contact angles by employing contact-mode and drip-mode, respectively. Water droplet of large volume (15 muL) had a smaller sliding angle than that of small volume (3 muL) when using the contact-mode due to the role of gravity despite the existence of large adhesive force between water droplet and the coating surface, while very small sliding angles were noted when using the drip-mode because of the existence of kinetic energy. The transmittance of fabricated coatings was enhanced and reduced, respectively, in the long and short wavelength ranges as compared with blank slide glass.