Due to the fact that the conventional bioceramic microspheres lack target function, novel litchi-like porous microspheres composed of a core of CaCO₃ and a tunable magnetic-hydroxyapatite (HA) shell were successfully prepared in this study. Antitumor drug, doxorubicin (DOX), was effectively loaded on the HA microspheres which possess magnetic targeting function. In addition, the HA shell, which had favorable biocompatibility and pH response characteristics, could be used to control release of loaded DOX from the litchi-like superparamagnetic microspheres in a simulated acidic tumor cell environment, effectively killing tumor cells and reducing toxic side effects to normal cells. The smart design presented in this study, which incorporates a tunable superparamagnetic shell and a controlled architecture, allows the sensitive release of drugs for efficient antitumor activity.

Dendritic fibrous nano-silica (DFNS), especially the sphere-shaped with three-dimensional (3D) center- radial channels and hierarchical pores, possess higher specific surface areas, larger pore volumes, higher pore permeability, more accessible internal spaces, etc. Guest substances (e.g., ultrasmall nanoparticles) can be loaded onto and transported in the radial nanochannels, or can even react with the chemically active sites in these nanochannels. As a result, DFNS can serve as promising platforms to construct novel nanocatalysts, adsorbent materials, and delivery systems for genes, proteins or drugs. A majority of investigations about DFNS have demonstrated that silica nanospheres with this special topography have inherent superiorities over traditional mesoporous MCM-41 or SBA-15, and can be perfect alternatives. Nevertheless, reviews on DFNS are limited, and there still exist plenty of issues that need to be probed into. Therefore, this comprehensive review provides a critical survey on DFNS’ structural characteristics, commonly used structural models, novel structures, real-time applications, etc. We sincerely expect that this paper could give material scientists and chemists certain inspiration to accelerate DFNS family’s booming evolution.

With polyoxyethylene-polyoxypropylene-polyoxyethylene (P123) as template, 1,3,5-trimethylbenzene (TMB) as swelling agent and tetramethoxysilane (TEOS) as silica source, mesocellular foam (MCF) with three dimensional (3D) cage-like mesopores linked by windows was successfully synthesized by hydrothermal method. N₂ isothermal adsorption characterization indicated that the largest pore size was 17.3 nm, and the other structural parameters as window size, specific surface area and pore volume were 8.2 nm, 770.3 m²/g, 2.3 cm³/g, respectively. MCF was employed as carrier for adsorption of DhaA which is an enzyme for sulfur mustard decontamination. The effect of pH to saturated adsorption capacity of DhaA in MCF was studied and the results showed that the largest loading amount of DhaA was achieved at pH 6.5. The adsorption kinetics followed Elovich kinetic model very well, and rate-determining step of this adsorption process was intraparticle diffusion. Adsorption isotherm curve of DhaA matched Sips model. The catalytic activity and conformation of DhaA changed obviously after being adsorbed in MCF. The residual activity of DhaA was 12.4% after being adsorbed, and the intrinsic fluorescence spectrum was found red shift. From the experimental results it can be observed that the big pore size, large specific surface area, and 3D cage-like structure of MCF facilitated the adsorption of DhaA, The electrostatic repulsion between DhaA and MCF influenced the adsorption process, and the conformation change of DhaA was the major factor of the decreased catalytic activity.

Porous and hollow hydroxyapatite (HAP) microspheres were synthesized successfully in hydrothermal method utilizing poly(allylamine hydrochloride) (PAH) as the crystal growth regulator. Effects of reaction time and concentration of the polymer on the growth of final products were investigated. Uniform microspheres with dense pores can be synthesized by controlling the PAH concentration (0.3-0.5 g/L) after 12 h hydrothermal reaction at 150℃. Formation of hollow microspheres includes different stages of early precursor microstructures, heterogeneous nucleation and phase transformations. At different stages, the cationic polyelectrolyte PAH plays an important role in regulating growth of hollow microspheres. Ibuprofen (IBU) was chosen as a typical model drug to study the drug loading and the desorption ability. The results show that porous and hollow microspheres have relatively high drug loading capacity (413.65 mg/g). Drug release of the microspheres is favorably pH-responsive, which may have close relationship with the surface properties of HAP nanorods. Date from this study suggest that the porous microspheres will have potential application as the targeted-drug carrier in the biomedicine field.

Silicon oxycarbide (SiOC) ultrafine fibers with uniform distribution were prepared via electrospinning of polycarbosilane (PCS)/polystyrene followed by oxidation and pyrolysis at 1100℃. The diameter of SiOC fibers ranged from 500 to 900 nm through adjusting PCS concentration. The average tensile strength of SiOC fiber mat was 8.88 MPa. The obtained SiOC fibers also displayed outstanding thermal stability and chemical resistance, making them promising materials as smart filters and catalyst supports in harsh environment.

Polymers, as substrate of composite material on the surface of spacecraft, have such advantages as light mass and high strength. Atomic oxygen (AO) is one of the highest content particles of low earth orbit, and high-energy high-flux AO bombardment causes the polymers’ surface erosion and mass loss at different degree, resulting in polymers degradation. Thus, AO is one of major threats in space environment that reduces reliability of space devices and shortens their working life span. This review summarized current global protection technologies from AO in recent years. Among them, surface chemical modification method with advantages of body-modification and protection coating, providing organic/inorganic composite with modified layer through comprehensive protection performance. This review discussed the method to explore the AO protection reaction mechanism by computational simulation. Computational simulation combined with experiments may reveal nature of the protection, facilitate future researches on AO protection, and provide guidance for fabrication surface polymer materials used in domestic parts of the aerospace craft, especially the large-scale flexible space solar cell array