Yannan Yang

Surfactant-Free Assembly of Mesoporous Carbon Hollow Spheres with Large Tunable Pore Sizes

Mesoporous carbon hollow spheres (MCHS) have wide applications, including catalysis, absorption, and energy storage/conversion. Herein, we report a one-pot, surfactant-free synthesis of MCHS using three molecules: resorcinol, formaldehyde, and tetrapropyl orthosilicate. The co-condensation process between the in situ generated silica primary particles and the polymer oligomers is regulated, leading to monodispersed MCHS with adjustable pore sizes from micropores to 13.9 nm. The resultant MCHS shows excellent performance for electrochemical double-layer capacitors with high capacitance (310 F g(-1) at 1 A g(-1)), excellent rate capability (157 F g(-1) at 50 A g(-1)), and outstanding cycling stability (98.6% capacity retention after 10 000 cycles at 10 A g(-1)). Our one-pot synthesis strategy is versatile and can be extended to fabricate metal oxide@mesoporous carbon yolk-shell structures in the absence of surfactant, paving the way toward designed synthesis of nanostructured mesoporous carbon composites for various applications.

Advances in silica based nanoparticles for targeted cancer therapy

UNLABELLED Targeted delivery of anticancer drug specifically to tumor site without damaging normal tissues has been the dream of all scientists fighting against cancer for decades. Recent breakthrough on nanotechnology based medicines has provided a possible tool to solve this puzzle. Among diverse nanomaterials that are under development and extensive study, silica based nanoparticles with vast advantages have attracted great attention. In this review, we concentrate on the recent progress using silica based nanoparticles, particularly mesoporous silica nanoparticles (MSNs), for targeted drug delivery applications. First, we discuss the passive targeting capability of silica based nanoparticles in relation to their physiochemical properties. Then, we focus on the recent advances of active targeting strategies involving tumor cell targeting, vascular targeting, nuclear targeting and multistage targeting, followed by an introduction to magnetic field directed targeting approach. We conclude with our personal perspectives on the remaining challenges and the possible future directions. FROM THE CLINICAL EDITOR Chemotherapy has been one of the mainstays of cancer treatment. The advances in nanotechnology has allowed the development of novel carrier systems for the delivery of anticancer drugs. Mesoporous silica has shown great promise in this respect. In this review article, the authors provided a comprehensive overview of the use of this nanoparticle in both passive, as well as active targeting in the field of oncology. The advantages of this particle were further discussed.

Biphasic Synthesis of Large‐Pore and Well‐Dispersed Benzene Bridged Mesoporous Organosilica Nanoparticles for Intracellular Protein Delivery

Large pore (4.6-7.6 nm) and well-dispersed benzene bridged mesoporous organosilica nanoparticles with uniform particle size of ≈50 nm are prepared via a biphasic approach. They can be directly used as nanocarriers without surface modification for the intracellular delivery of therapeutic proteins.

Silica Nanopollens Enhance Adhesion for Long-Term Bacterial Inhibition.

Natures creations with spiky topological features typically exhibit intriguing surface adhesive properties. From micrometer-sized pollen grains that can easily stick to hairy insects for pollination to nanoscale virus particles that are highly infectious toward host cells, multivalent interactions are formed taking advantage of rough surfaces. Herein, this nature-inspired concept is employed to develop novel drug delivery nanocarriers for antimicrobial applications. A facile new approach is developed to fabricate silica nanopollens (mesoporous silica nanospheres with rough surfaces), which show enhanced adhesion toward bacteria surfaces compared to their counterparts with smooth surfaces. Lysozyme, a natural antimicrobial enzyme, is loaded into silica nanopollens and shows sustained release behavior, potent antimicrobial activity, and long-term total bacterial inhibition up to 3 days toward Escherichia coli. The potent antibacterial activity of lysozyme-loaded silica nanopollens is further demonstrated ex vivo by using a small-intestine infection model. Our strategy provides a novel pathway in the rational design of nanocarriers for efficient drug delivery.

Core-Cone Structured Monodispersed Mesoporous Silica Nanoparticles with Ultra-large Cavity for Protein Delivery.

A new type of monodispersed mesoporous silica nanoparticles with a core-cone structure (MSN-CC) has been synthesized. The large cone-shaped pores are formed by silica lamellae closely packed encircling a spherical core, showing a structure similar to the flower dahlia. MSN-CC has a large pore size of 45 nm and a high pore volume of 2.59 cm(3) g(-1). MSN-CC demonstrates a high loading capacity of large proteins and successfully delivers active β-galactosidase into cells, showing their potential as efficient nanocarriers for the cellular delivery of proteins with large molecular weights.

Mesoporous Magnesium Oxide Hollow Spheres as Superior Arsenite Adsorbent: Synthesis and Adsorption Behavior

Arsenic contamination in natural water has posed a significant threat to global health due to its toxicity and carcinogenity. Adsorption technology is an easy and flexible method for arsenic removal with high efficiency. In this Article, we demonstrated the synthesis of mesoporous MgO hollow spheres (MgO-HS) and their application as high performance arsenite (As(III)) adsorbent. MgO-HS with uniform particle size (∼180 nm), high specific surface area (175 m(2) g(-1)), and distinguished mesopores (9.5 nm in size) have been prepared by hard-templating approach using mesoporous hollow carbon spheres as templates. An ultrahigh maximum As(III) adsorption capacity (Qmax) of 892 mg g(-1) was achieved in batch As(III) removal study. Adsorption kinetic study demonstrated that MgO-HS could enable As(III) adsorption 6 times faster as a commercial MgO adsorbent. The ultrahigh adsorption capacity and faster adsorption kinetics were attributed to the unique structure and morphology of MgO-HS that enabled fast transformation into a flower-like porous structure composed of ultrathin Mg(OH)2 nanosheets. This in situ formed structure provided abundant and highly accessible hydroxyl groups, which enhanced the adsorption performance toward As(III). The outstanding As(III) removal capability of MgO-HS showed their great promise as highly efficient adsorbents for As(III) sequestration from contaminated water.

Understanding the contribution of surface roughness and hydrophobic modification of silica nanoparticles to enhanced therapeutic protein delivery

Intracellular protein delivery holds great promise for cancer therapy. In this work, the individual and combined contribution of the surface roughness and hydrophobic modification (octadecyl-group) of silica nanoparticles has been studied in a number of events for cellular delivery of therapeutic proteins, including loading capacity, release behaviour, cellular uptake and endo/lysosomal escape. Both surface roughening and hydrophobic modification enhance the protein adsorption capacity and sustained release, while the contribution from the surface roughness is higher for loading capacity and hydrophobic modification is more effective for sustained protein release. Both structural parameters improve the cellular uptake performance; however the difference in the contribution is cell type-dependent. Only the hydrophobic modification shows a contribution to endo/lysosomal escape, independent of the surface topography. Octadecyl-functionalized rough silica nanoparticles thus show the best performance in therapeutic protein (RNase A) delivery, causing significant cell viability inhibition in different cancer cells among all groups under study.

Multi-shelled dendritic mesoporous organosilica hollow spheres: roles of composition and architecture in cancer immunotherapy

Developing potent adjuvants for the stimulation of robust immune response is central for effective cancer immunotherapy. Double-shelled dendritic mesoporous organosilica hollow spheres are an excellent adjuvant and provide superior immunity in cancer immunotherapy, and better than their counterparts either with a pure silica composition or a single-walled architecture. This study provides new insights in the rational design of effective nanostructured adjuvants for vaccine developments.

Small-sized and large-pore dendritic mesoporous silica nanoparticles enhance antimicrobial enzyme delivery

The abuse of antibiotics has led to the emergence of antibiotic resistant bacteria and high threats to human health. The search for safe and effective alternatives to traditional antibiotics is growing worldwide. In this article, we report the synthesis of large pore dendritic mesoporous silica nanoparticles (DMSNs) with controllable particle sizes and investigate the relationship between the particle size of DMSNs and their antibacterial enzyme delivery performance. The choice of dual-functional perfluorocarbon anions with both low surface tension and interaction with cationic surfactants enables the synthesis of DMSNs with tunable particle size and pore size. After loading with lysozyme, a naturally occurring antimicrobial enzyme, DMSNs with a large pore size of 22.4 nm and a small particle size of 79 nm show significantly better antibacterial activity compared to either DMSNs with a larger particle size (160 nm) or MSNs with a smaller pore size (2.4 nm) while the other parameter is similar. The optimized DMSNs loaded with lysozyme exhibit total inhibition towards Escherichia coli (E. coli) throughout five days. Our study provides new insights into the controllable synthesis of nano-carriers for antimicrobial protein delivery applications.

An approach to prepare polyethylenimine functionalized silica-based spheres with small size for siRNA delivery

A novel approach has been developed to prepare polyethylenimine functionalized hybrid silica spheres with a diameter of ∼10 nm, which show excellent delivery efficiency of siRNA into osteosarcoma cancer cells and human colon cancer cells with a significant cell inhibition comparable to commercial agents.