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Surface-functionalized silica nanoparticles can deliver DNA 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 and drugs 9 , 10 , 11 , 12 , 13 , 14 , 15 into animal cells and tissues. However, their use in plants is limited by the cell wall present in plant cells. Here we show a honeycomb mesoporous silica nanoparticle (MSN) system with 3-nm pores that can transport DNA and chemicals into isolated plant cells and intact leaves. We loaded the MSN with the gene and its chemical inducer and capped the ends with gold nanoparticles to keep the molecules from leaching out. Uncapping the gold nanoparticles released the chemicals and triggered gene expression in the plants under controlled-release conditions. Further developments such as pore enlargement and multifunctionalization of these MSNs may offer new possibilities in target-specific delivery of proteins, nucleotides and chemicals in plant biotechnology.

The delivery of proteins instead of DNA into plant cells allows for a transient presence of the protein or enzyme that can be useful for biochemical analysis or genome modifications. This may be of particular interest for genome editing, because it can avoid DNA (transgene) integration into the genome and generate precisely modified \"nontransgenic\" plants. In this work, we explore direct protein delivery to plant cells using mesoporous silica nanoparticles (MSNs) as carriers to deliver Cre recombinase protein into maize (Zea mays) cells. Cre protein was loaded inside the pores of gold-plated MSNs, and these particles were delivered by the biolistic method to plant cells harboring loxP sites flanking a selection gene and a reporter gene. Cre protein was released inside the cell, leading to recombination of the loxP sites and elimination of both genes. Visual selection was used to select recombination events from which fertile plants were regenerated. Up to 20% of bombarded embryos produced calli with the recombined loxP sites under our experimental conditions. This direct and reproducible technology offers an alternative for DNA-free genome-editing technologies in which MSNs can be tailored to accommodate the desired enzyme and to reach the desired tissue through the biolistic method.

A biosensor has been developed based on induced wavelength shifts in the Fabry-Perot fringes in the visible-light reflection spectrum of appropriately derivatized thin films of porous silicon semiconductors. Binding of molecules induced changes in the refractive index of the porous silicon. The validity and sensitivity of the system are demonstrated for small organic molecules (biotin and digoxigenin), 16-nucleotide DNA oligomers, and proteins (streptavidin and antibodies) at pico- and femtomolar analyte concentrations. The sensor is also highly effective for detecting single and multilayered molecular assemblies.

This review details the recent advancements in the design of mesoporous silica nanomaterials for controlled release drug, gene and neurotransmitter delivery applications. The high surface area (>900 m /g), tunable pore diameter (2-20 nm) and uniform mesoporous structure (hexagonal channels or cubic pores) of the mesoporous silicas offer a unique advantage for loading and releasing large quantities of biomedical agents. Recent breakthroughs in controlling the particle size and shape of these materials have greatly improved the biocompatibility and the cellular uptake efficiency. The strategy of using various removable capping moieties, such as photo- or redox-responsive organic groups, inorganic nanoparticles, dendrimers and polymers, to encapsulate guest biomolecules inside the porous matrices further enables the utilization of these surface-functionalized mesoporous silica nanomaterials for stimuli-responsive controlled release and . In addition to the reviewed studies, many new and exciting applications of these novel materials will soon be realized.

A series of core/shell, iron oxide nanoparticle embedded magnetic mesoporous silica nanoparticle materials with radial (MMSN‐r) and hexagonal (MMSN‐h) porous structures are synthesized and their capacity to load and release the anticancer drugs, 9‐aminoacridine (9AA) and camptothecin (CPT) are investigated. Although effective release of 9AA is observed for nonfunctionalized MMSN, its release from the phenylethyl‐functionalized hexagonal MMSN material (Ph‐MMSN‐h) was hindered. Conversely, the loading and release of CPT is promoted by the presence of the phenylethyl functionality inside the mesopores of MMSN, whereas very low release of CPT was observed from nonfunctionalized MMSN material. Controlled‐release properties of the drug‐loaded magnetic materials were confirmed by viability studies on Chinese hamster ovarian (CHO) cells, which revealed efficient cytotoxic activity of CPT‐loaded Ph‐MMSN‐h and 9AA‐loaded MMSN‐h materials. In addition, it was demonstrated that applying an external magnetic field to induce agitation of the drug leaded materials promoted the release of anticancer drugs from the magnetic materials. It is envisioned that the MMSN materials could be effectively applied for externally controlled, selective drug delivery to tumor tissues. A series of core/shell magnetic mesoporous silica nanoparticle (MMSN) materials were prepared. The loading and release of anticancer drugs, 9‐aminoacridine (9AA) and camptothecin (CPT), as well as cytotoxic activity of drug loaded materials, is influenced by the presence of phenylethyl functionalization inside the MMSN mesopores (see figure). An externally applied magnetic field accelerates the drug release from the materials.

The unique structural features of mesoporous silica nanoparticles (MSN) have made them very useful in biological applications, such as gene therapy and drug delivery. Flow cytometry, confocal microscopy, and electron microscopy have been used for observing the endocytosis of MSN. However, flow cytometry cannot directly observe the process of endocytosis. Confocal microscopy requires fluorescence labeling of the cells. Electron microscopy can only utilize fixed cells. In the present work, we demonstrate for the first time that differential interference contrast (DIC) microscopy can be used to observe the entire endocytosis process of MSN into living human lung cancer cells (A549) without fluorescence staining. There are three physical observables that characterize the locations of MSN and the stages of the endocytosis process: motion, shape, and vertical position. When it was outside the cell, the MSN underwent significant Brownian motion in the cell growth medium. When it was trapped on the cell membrane, the motion of the MSN was greatly limited. After the MSN had entered the cell, it resumed motion at a much slower speed because the cytoplasm is more viscous than the cell growth medium and the cellular cytoskeleton networks act as obstacles. Moreover, there were shape changes around the MSN due to the formation of a vesicle after the MSN had been trapped on the cell membrane and prior to entry into the cell. Finally, by coupling a motorized vertical stage to the DIC microscope, we recorded the location of the MSN in three dimensions. Such accurate 3D particle tracking ability in living cells is essential for studies of selectively targeted drug delivery based on endocytosis.

A series of urea- and thiourea-functionalized mesoporous silica nanoparticles (MSN) was synthesized. These materials exhibited a superior catalytic reactivity for Diels–Alder reaction than their homogeneous analogues. The reactivity enhancement was attributed to the site isolation effect induced by the heterogenization of individual catalytic group. The surface hydrogen bonding between the organic catalysts and silanols also improved the catalytic reactivity.

A series of calcium containing silicate mixed oxide materials has been developed for biodiesel production. It has been shown that these materials can catalyze transesterification reactions from feedstocks with various fatty acid contents. However, their reaction kinetics for biodiesel synthesis was very slow compared to that of homogeneous-catalyst-catalyzed reactions. Herein, we report fast-reacting solid catalysts for biodiesel production. Two types of materials have been developed: a non-porous and an anionic-surfactant-templated catalysts. Compared to previously reported transesterification reaction by mesoporous calcium containing silicate catalysts, the reaction rates from both families were much faster. In addition, both the preparation time of catalysts and the cost of preparation were significantly reduced. Details in material synthesis and its effect on catalysis are discussed.

Non-toxicity in multifunctional inorganic nanoparticles is rare. However, with careful engineering of silicon-based nanoparticles they can be used in vivo as imaging and drug-delivery agents and later degraded and cleared without toxic effects.