Spherical, monodisperse, functional bridged polysilsesquioxane nanoparticles

Multimodal Polysilsesquioxane Nanoparticles for Combinatorial Therapy and Gene Delivery in Triple-Negative Breast Cancer

Multifunctional hybrid nanoparticles are being developed to carry a wide variety of therapeutic and imaging agents for multiple biomedical applications. Polysilsesquioxane (PSilQ) nanoparticles are a promising hybrid platform with numerous advantages to be used as a delivery system. In this report, we demonstrate the ability of a stimuli-responsive PSilQ-based platform to transport and deliver simultaneously protoporphyrin IX, curcumin, and RNA interference inducers inside human cells. This multimodal delivery system shows a synergistic performance for the combined phototherapy and chemotherapy of triple-negative breast cancer and can be used for efficient transfection of therapeutic nucleic acids. The current work represents the first report of using the PSilQ platform for the combined phototherapy and chemotherapy and gene delivery.

Degradability and Clearance of Silicon, Organosilica, Silsesquioxane, Silica Mixed Oxide, and Mesoporous Silica Nanoparticles

The biorelated degradability and clearance of siliceous nanomaterials have been questioned worldwide, since they are crucial prerequisites for the successful translation in clinics. Typically, the degradability and biocompatibility of mesoporous silica nanoparticles (MSNs) have been an ongoing discussion in research circles. The reason for such a concern is that approved pharmaceutical products must not accumulate in the human body, to prevent severe and unpredictable side-effects. Here, the biorelated degradability and clearance of silicon and silica nanoparticles (NPs) are comprehensively summarized. The influence of the size, morphology, surface area, pore size, and surface functional groups, to name a few, on the degradability of silicon and silica NPs is described. The noncovalent organic doping of silica and the covalent incorporation of either hydrolytically stable or redox- and enzymatically cleavable silsesquioxanes is then described for organosilica, bridged silsesquioxane (BS), and periodic mesoporous organosilica (PMO) NPs. Inorganically doped silica particles such as calcium-, iron-, manganese-, and zirconium-doped NPs, also have radically different hydrolytic stabilities. To conclude, the degradability and clearance timelines of various siliceous nanomaterials are compared and it is highlighted that researchers can select a specific nanomaterial in this large family according to the targeted applications and the required clearance kinetics.

Organosilica hybrid nanomaterials with a high organic content: syntheses and applications of silsesquioxanes

Organic-inorganic hybrid materials garner properties from their organic and inorganic matrices as well as synergistic features, and therefore have recently attracted much attention at the nanoscale. Non-porous organosilica hybrid nanomaterials with a high organic content such as silsesquioxanes (R-SiO_1.5, with R organic groups) and bridged silsesquioxanes (O_1.5Si-R-SiO_1.5) are especially attractive hybrids since they provide 20 to 80 weight percent of organic functional groups in addition to the known chemistry and stability of silica. In the organosilica family, silsesquioxanes (R-SiO_1.5) stand between silicas (SiO₂) and silicones (R₂SiO), and are variously called organosilicas, ormosil (organically-modified silica), polysilsesquioxanes and silica hybrids. Herein, we comprehensively review non-porous silsesquioxane and bridged silsesquioxane nanomaterials and their applications in nanomedicine, electro-optics, and catalysis.

Redox-Responsive Porphyrin-Based Polysilsesquioxane Nanoparticles for Photodynamic Therapy of Cancer Cells

The development of stimulus-responsive photosensitizer delivery systems that carry a high payload of photosensitizers is of great importance in photodynamic therapy. In this study, redox-responsive polysilsesquioxane nanoparticles (PSilQNPs) built by a reverse microemulsion approach using 5,10,15,20-tetrakis(carboxyphenyl) porphyrin (TCPP) silane derivatives as building blocks, were successfully fabricated. The structural properties of TCPP-PSilQNPs were characterized by dynamic light scattering (DLS)/ζ-potential, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The photophysical properties were determined by UV-vis and fluorescence spectroscopy. The quantity of singlet oxygen generated in solution was measured using 1,3-diphenylisobenzofuran. The redox-responsive release of TCPP molecules was successfully demonstrated in solution in the presence of a reducing agent. The internalization of TCPP-PSilQNPs in cancer cells was investigated using laser scanning confocal microscopy. Phototoxicity experiments in vitro showed that the redox-responsive TCPP-PSilQNPs exhibited an improved phototherapeutic effect on cervical cancer cells compared to a non-responsive TCPP-PSilQNP control material.

Photoresponsive Bridged Silsesquioxane Nanoparticles with Tunable Morphology for Light-Triggered Plasmid DNA Delivery

Bridged silsesquioxane nanocomposites with tunable morphologies incorporating o-nitrophenylene-ammonium bridges are described. The systematic screening of the sol-gel parameters allowed the material to reach the nanoscale with controlled dense and hollow structures of 100-200 nm. The hybrid composition of silsesquioxanes with 50% organic content homogeneously distributed in the nanomaterials endowed them with photoresponsive properties. Light irradiation was performed to reverse the surface charge of nanoparticles from +46 to -39 mV via a photoreaction of the organic fragments within the particles, as confirmed by spectroscopic monitorings. Furthermore, such nanoparticles were applied for the first time for the on-demand delivery of plasmid DNA in HeLa cancer cells via light actuation.

Enhanced two-photon fluorescence imaging and therapy of cancer cells via Gold@bridged silsesquioxane nanoparticles

A two-photon photosensitizer with four triethoxysilyl groups is synthesized through the click reaction. This photosensitizer allows the design of bridged silsesquioxane (BS) nanoparticles through a sol-gel process; moreover, gold core BS shells or BS nanoparticles decorated with gold nanospheres are synthesized. An enhancement of the two-photon properties is noted with gold and the nanoparticles are efficient for two-photon imaging and two-photon photodynamic therapy of cancer cells.

Synthesis of disulfide-based biodegradable bridged silsesquioxane nanoparticles for two-photon imaging and therapy of cancer cells

Biodegradable bridged silsesquioxane nanoparticles for two-photon imaging and therapy of cancer cells are described.

Biodegradable polysilsesquioxane nanoparticles as efficient contrast agents for magnetic resonance imaging

Polysilsesquioxane (PSQ) nanoparticles are crosslinked homopolymers formed by condensation of functionalized trialkoxysilanes, and provide an interesting platform for developing biologically and biomedically relevant nanomaterials. In this work, the design and synthesis of biodegradable PSQ particles with extremely high payloads of paramagnetic Gd(III) centers is explored, for use as efficient contrast agents for magnetic resonance imaging (MRI). Two new bis(trialkoxysilyl) derivatives of Gd(III) diethylenetriamine pentaacetate (Gd-DTPA) containing disulfide linkages are synthesized and used to form biodegradable Gd-PSQ particles by base-catalyzed condensation reactions in reverse microemulsions. The Gd-PSQ particles, PSQ-1 and PSQ-2, carry 53.8 wt% and 49.3 wt% of Gd-DTPA derivatives, respectively. In addition, the surface carboxy groups on the PSQ-2 particles can be modified with polyethylene glycol (PEG) and the anisamide (AA) ligand to enhance biocompatibility and cell uptake, respectively. The Gd-PSQ particles are readily degradable to release the constituent Gd(III) chelates in the presence of endogenous reducing agents such as cysteine and glutathione. The MR relaxivities of the Gd-PSQ particles are determined using a 3T MR scanner, with r1 values ranging from 5.9 to 17.8 mMs(-1) on a per-Gd basis. Finally, the high sensitivity of the Gd-PSQ particles as T1 -weighted MR contrast agents is demonstrated with in vitro MR imaging of human lung and pancreatic cancer cells. The enhanced efficiency of the anisamide-functionalized PSQ-2 particles as a contrast agent is corroborated by both confocal laser scanning microscopy imaging and ICP-MS analysis of Gd content in vitro.

Nonporous Silica Nanoparticles for Nanomedicine Application

Nanomedicine, the use of nanotechnology for biomedical applications, has potential to change the landscape of the diagnosis and therapy of many diseases. In the past several decades, the advancement in nanotechnology and material science has resulted in a large number of organic and inorganic nanomedicine platforms. Silica nanoparticles (NPs), which exhibit many unique properties, offer a promising drug delivery platform to realize the potential of nanomedicine. Mesoporous silica NPs have been extensively reviewed previously. Here we review the current state of the development and application of nonporous silica NPs for drug delivery and molecular imaging.

A facile strategy for in situ core-template-functionalizing siliceous hollow nanospheres for guest species entrapment

The shell wall-functionalized siliceous hollow nanospheres (SHNs) with functional molecules represent an important class of nanocarriers for a rich range of potential applications. Herein, a self-templated approach has been developed for the synthesis of in situ functionalized SHNs, in which the biocompatible long-chain polycarboxylates (i.e., polyacrylate, polyaspartate, gelatin) provide the framework for silica precursor deposition by simply controlling chain conformation with divalent metal ions (i.e., Ca2+, Sr2+), without the intervention of any external templates. Metal ions play crucial roles in the formation of organic vesicle templates by modulating the long chains of polymers and preventing them from separation by washing process. We also show that, by in situ functionalizing the shell wall of SHNs, it is capable of entrapping nearly an eightfold quantity of vitamin Bc in comparison to the bare bulk silica nanospheres. These results confirm the feasibility of guest species entrapment in the functionalized shell wall, and SHNs are effective carriers of guest (bio-)molecules potentially for a variety of biomedical applications. By rationally choosing the functional (self-templating) molecules, this concept may represent a general strategy for the production of functionalized silica hollow structures.

High-contrast solid-state electrochromic devices of viologen-bridged polysilsesquioxane nanoparticles fabricated by layer-by-layer assembly

Water-soluble silsesquioxane nanoparticles (NPs) incorporating viologen groups (PXV; 1,1'-bis[3-(trimethoxysilyl)propyl]-4,4'-bipyridinium iodide) have been synthesized by sol-gel polymerization. The electrochromic properties of the bulk film fabricated by layer-by-layer (LbL) assembly have been examined, along with their incorporation into solid-state devices. The orange LbL films show high thermal stability and exhibit a maximum UV-vis absorption at 550 nm. Electrochromic switching of the NPs in liquid electrolyte as well as in the solid state was evaluated by a kinetic study via measurement of the change in transmission (% T) at the maximum contrast. Cyclic voltammograms of the PXV NP LbL films exhibit a reversible reduction at -0.6 V vs Ag/AgCl in a 0.1 M NaClO4(aq) solution, revealing good electrochromic stability, with a color change from orange to dark purple-blue at applied potentials ranging from -0.7 to -1.3 V. Cathodically coloring PXV NP solid-state devices exhibit a switching time of a few seconds between the purple-blue reduced state and the orange oxidized state, showing a contrast of 50% at 550 nm and a coloration efficiency of 205 cm2/C. Their solubility and fairly fast electrochromic switching ( approximately 3 s) at low switching voltages (between 0 and 3.0 V), along with their stability under atmospheric conditions, make PXV NPs good candidates for electrochromic displays.

One-step synthesis of highly monodisperse hybrid silica spheres in aqueous solution

An effective and reproducible method of preparing highly monodisperse organic-inorganic hybrid silica spheres was studied. One process, one precursor (organosilane) and one solvent (water) were used in our experiments. The size of hybrid silica spheres could be adjusted from 360 to 770 nm with relative standard deviation below 2% by controlling the concentration of the organosilane precursor and the ammonia catalyst. The increasing of the precursor concentration increases the particle size while the catalyst concentration has a reverse effect on the particle size. The concept of homogeneous nucleation and growth processes are introduced to explain the formation mechanism and the effect of reaction conditions. The scanning electron microscopy (SEM) images illustrate the copiousness in quantity and the uniformity in size/shape of the particles that could be routinely accomplished in this synthesis. Fourier transform infrared (FT-IR) and (29)Si nuclear magnetic resonance (NMR) spectra confirm the structure of vinyl hybrid silica spheres, where the vinyl group (-CH=CH(2)) exists and connects to the silicon atom. This method has also been extended to design and prepare other organic-inorganic hybrid materials especially in monodisperse surface-modified silica spheres.