Mesoporous Silica Nanospheres Research Articles

One‐Step Synthesis of Thiol‐Functional Mesoporous Silica Nanospheres and Selective Removal of Cationic Dyes

AbstractThe surface characteristics of nanoparticles have a huge impact on adsorption effects. In this paper, thiol‐functional mesoporous silica nanospheres (MSNs−SH) are successfully prepared through simple one‐step hydrolysis and co‐condensation of tetraethyl orthosilicate and (3‐mercaptopropyl) triethoxysilane with hexadecyltrimethylammonium bromide and sulfobetaine 12 as dual‐template. The obtained MSNs−SH have high surface area (1260 m2 g−1), accessible mesopores (2.2 nm), great pore volume (1.7 cm3 g−1), and uniform adjustable diameter (90 nm). Furthermore, the diameter and pore‐size of MSNs−SH can be controlled via adjusting the ethanol content in the synthesis system. MSNs−SH exhibit a fast adsorption kinetics, marked adsorption capacity of cationic rhodamine B (RB 534.2 mg g−1), and remarkable selective adsorption for cationic dyes. Theoretical analysis reveals the adsorption behavior of RB on MSNs−SH follows the Langmuir isotherm models and pseudo‐second‐order kinetic. Additionally, the thermodynamic results indicate that the adsorption process is a spontaneous process driven by temperature. The results demonstrate that MSNs−SH are greatly potential for effectively removing cationic dyes from wastewater, with the advantages of simple preparation, high adsorption performance and perfect selectivity.

Chemoenzymatic cascade conversion of methyl parathion to 4-aminophenol with immobilized organophosphate hydrolase onto Cu-MOF-loaded mesoporous silica

Organophosphates (OPs), essential pesticide ingredients, are highly toxic and environmentally problematic. OPs can be efficiently hydrolyzed by the enzyme organophosphorus hydrolase (OPH). However, the resulting p-nitrophenol (4-NP) is still toxic, and its chemical reduction to p-aminophenol (4-AP) can be environmentally friendly and increase economic value. We constructed a chemical-enzymatic cascade catalyst system for methyl parathion (MP) using OPH and a copper-based metal-organic framework (HKUST-1) with 4-NP reduction catalytic activity. The nano-HKUST-1 was first loaded into aminated mesoporous silica nanospheres (MSN-NH2) to construct HKUST-1@MSN-NH2, and then OPH was immobilized into the HKUST-1@MSN-NH2 pores by a covalent method to obtain OPH@HKUST-1@MSN-NH2. The resulting composite catalyst, OPH@HKUST-1@MSN-NH2, achieved chemoenzymatic cascade catalysis of MP hydrolysis to 4-NP and subsequent reduction to 4-AP. The composite nano-biocatalyst has good catalytic performance and reusability, which can rapidly convert entirely 50 μM MP to 4-AP in 8 min at a dosage of 30 mM NaBH4. Still, it has 77% activity after 10 cycles and a stable material structure. The present study provides a strategy for constructing a chemoenzymatic cascade catalytic system, and the obtained composite nano catalysts achieve the continuous degradation and resourceful conversion of organophosphorus pollutants, which has specific practical application value.

Sol-gel synthesis, physicochemical characteristics and in vitro pH-responsive metformin drug release of uniformly polydopamine coated mesoporous silica nanospheres

A recent attention has been paid to the repurposing potential of metformin drug for cancer chemotherapy. Herein, pH-responsive metformin drug delivery nanocarriers were achieved using sol-gel synthesized mesoporous silica nanospheres (MSN) uniformly coated with polydopamine (PDA) shell. The PDA coating shell around the MSN surface was in situ formed through oxidative self-polymerization of dopamine monomers in an alkaline solution at room temperature. The microstructure, structural and textural characteristics of PDA@MSN were examined and compared to uncoated MSN. Furthermore, PDA coated metformin (MET) drug-loaded MSN were used to study the pH-responsive MET drug release behaviour under neutral and acidic conditions. The in vitro release test showed that the PDA coating shell not only protects MET drug leakage under normal physiological conditions (pH 7.4) but also allows for its controlled/sustained release in acidic conditions (pH 4.5 and pH 5.5) which closely mimic the intracellular acidity (pH 4.5–5.5) of endosomes/lysosomes formed around drug-loaded nanocarriers after their endocytosis by cancer cells.

Mesoporous collapsing encapsulated carbon dots: Direct evidence for the effect of multiple-confined interactions of silica on efficient long-lived phosphorescence

Coupling with a matrix is the common strategy to improve the phosphorescence performance of carbon dots (CDs). However, there is a lack of clear and direct evidence about the formation mechanism of the inner relationship between CDs and matrix, and the specific effect of matrix on the phosphorescence performance. Mesoporous silica nanospheres (MSNs) were used as the research model to provide the direct evidence of the dense structure formation process and to construct a quantum chemical theoretical computational model of the effect of dense matrix on phosphorescence performance. Due to the multiple domain-limiting effects of rigid Si-C covalent bonds and SiO2 dense structure, the calcined-carbonized polymer dots-mesoporous silica nanospheres (C-CPDs-MSNs) can exhibit thermally activated delayed fluorescence (TADF) by tuning the HOMO-LUMO gap and enriching the electrons in the surface region. With a long lifetime of 3.07 s, the composite can also maintain stable phosphorescence performance under harsh conditions and has been successfully applied in multilevel information encryption, fingerprint identification, and cellular imaging. This work provides the direct evidence for the process of dense SiO2 structure enhancing the phosphorescence performance of CDs and offers a general strategy and method for the design and preparation of efficient and practical CDs-based phosphorescent materials.

Imidazolium based Ionic liquid Anchored over Dendritic Mesoporous Silica Nanospheres possessing a Magnetic Core as an Efficient and Recyclable Base Catalyst

AbstractIn this study, Magnetic core‐shell dendritic mesoporous silica nanospheres immobilized with imidazolium‐based di‐cationic ionic liquid (Fe3O4@SiO2@DSiO2‐Im‐IL) possessing a large surface area and numerous active site for adsorption of various molecules to carry out organic transformations have been successfully developed. The synthesized nanocatalyst was found to be easily recyclable by applying external magnetic force. The structure, morphology, thermal stability, and magnetic behavior of the synthesized magnetic nanocatalyst were confirmed by different physiochemical techniques like FT‐IR, P‐XRD, FE‐SEM, TGA, VSM, BET, and TEM analysis. The efficiency of the developed heterogeneous nanocatalyst has been investigated for the green synthesis of numerous benzopyran derivatives by employing different aldehydes and active methylene compounds. The catalyst exhibits marvellous activity and efficiency in terms of high product yield, less catalyst use, and wide substrate scope even at room temperature. Finally, after the successful formation of the product, the catalyst was regenerated by utilizing an external magnetic field. The catalyst has been reused multiple times without any noteworthy loss in its activity which confirms the stability of the developed catalyst. The preparation of the catalyst is cost‐effective, and shows atom economy with the utilization of green solvent and without any waste production, which authenticates that it could be a greener pathway for the synthesis of the benzopyran derivatives.

Synthesis of graphene quantum dots inside a nanoreactor for fluorescence detection of dopamine

A label-free fluorescence sensor for selective detection of dopamine (DA) was developed by using graphene quantum dots (GQDs) as fluorescence probes. The GQDs were prepared via a top-down acid vapor oxidation strategy, in which a hollow carbon @ mesoporous silica nanosphere (h-C@mesoSiO2) serves as nanoreactor and only 1 mL of HNO3 was used as scissors for quickly cleaving the thin carbon layer in the nanospace of h-C@mesoSiO2. The method not only effectively avoids a tedious separation process but also endows GQDs with uniform size and good dispersion. And the as-prepared GQDs display good linear fluorescence response to DA in the range of 0.24–5.86 mM with a low detection limit of 12.7 nM. The proposed sensor shows high selectivity and satisfying recovery for DA detection in human urine. The good specificity toward DA may be due to a) the carboxyl groups on the surface of GQDs can interact with the amine functional groups in DA through electrostatic interactions and b) this specificity is further enhanced by the π–π interaction between GQDs and DA. Importantly, the work not only provides an avenue for the controllable synthesis of GQDs, but also expands the application of GQDs prepared by top-down method to DA sensor.

Controlled synthesis of sulfhydryl-dendritic mesoporous silica nanospheres for ultrafast extraction and sensitive analysis of organochlorine herbicides containing amide groups

The distinctive morphology of dendritic mesoporous silica nanoparticles (DMSN) has recently attracted considerable attention in scientific community. However, synthesis of DMSN with well-defined structure and uniform size for ultrafast extraction of trace herbicide residues from environmental and food samples remains to be a compelling challenge. In this study, sulfhydryl functionalized dendritic mesoporous silica (SH-DMSN) was synthesized and the SH-DMSN showcases monodisperse microspheres with flower shape and precisely tailored and controllable pore sizes. This distinctive structural configuration accelerates mass transfer within the silica layer, resulting in heightened adsorption efficiencies. Furthermore, the particle sizes (455, 765, and 808) of the adsorbent can be meticulously fine-tuned by introducing distinct templates. Specifically, when the particle size is 765 nm, the optimized SH-DMSN exhibits a substantial specific surface area (691.32 m²/g), outstanding adsorption efficiencies (>90 %), remarkably swift adsorption and desorption kinetics (2 min and 3 min, respectively), and exceptional stability. The superior adsorption capabilities of this novel adsorbent, ranging from 481.65 to 1021.7 µg/g for organochlorine herbicides containing amide groups, can be attributed to the interplay of S-π interactions, halogen bonding, and electrostatic attraction interaction. These interactions involve the lone pair electrons of sulfhydryl and silanol groups with the π-electrons, halogen atoms and amide groups in herbicide molecules. This study not only offers a new perspective on advancing the practical utilization of dendritic mesoporous silica but also provides a pragmatic strategy for the separation and analysis of herbicides in diverse sample matrices.

Microcapsules of mesoporous silica and cyclodextrin modified loaded with nonanal and decanal for effective control of Sitotroga cerealella in grain storage environments.

The Angoumois grain moth, Sitotroga cerealella, is a destructive pest of maize, wheat, and rice, causing economic losses and threatening food security. This study aimed to develop and characterize microcapsules of mesoporous silica nanospheres (MSN) and cyclodextrin-modified mesoporous silica nanospheres (CDMSN) containing two aldehydes, nonanal and decanal, found in plant essential oils, to assess their attractiveness to S. cerealella populations. Microcapsules with 2:1 ratio of nonanal and decanal exhibited an average encapsulation efficiency of 39.82% for MSN loaded with nonanal and decanal (MSN-ND) and 46.10% for CDMSN loaded with nonanal and decanal (CDMSN-ND). They have an elliptical shape with particle sizes of 115 nm for MSN and 175 nm for CDMSN. Gas chromatography-mass spectrometry analysis revealed in vitro release of nonanal in MSN at 96.24% and decanal at 96.42% by the 36th day. CDMSN showed releases of 93.83% for nonanal and 93.74% for decanal by the 50th day. CDMSN-ND attracted adult S. cerealella for 43 days, while MSN-ND remained effective for 29 days. In mass trapping assays in simulated grain warehouse, both MSN-ND and CDMSN-ND trapped over 50% of the adult population within 7 days, significantly reducing grain infestation rates below 10% by inhibiting F1 adult emergence. At temperatures ranging from 20 °C to 35 °C, both microcapsules exhibited significant and effective attraction rates for S. cerealella. Stored wheat seeds treated with CDMSN and CDMSN-ND over 1 year showed no significant differences in key germination parameters. Microencapsulated nonanal and decanal offer a promising, sustainable approach for controlling S. cerealella infestation in stored grains, contributing to global food security. © 2024 Society of Chemical Industry.

Robust enzyme-iron oxide nanoparticle composites entrapped in mesoporous silica nanospheres and their properties

Effective preservation of enzyme activity is required for using immobilized enzymes to catalyze reactions. To this end, the co-immobilization of an enzyme and nanoparticles in a nanosphere system using a reverse microemulsion is proposed. Iron oxide nanoparticles (MNPs) and carboxyl esterase (CE) were encapsulated in spherical mesoporous silica nanospheres. After immobilization, the encapsulated CE retained approximately 10.9% of the specific activity of free CE for the hydrolysis reaction. Regarding its stability during storage, the immobilized CE retained 52% and 30% of its initial activity after 30 days at 25 °C and under rigorous incubation conditions, respectively. Utilizing this magnetically separable property enabled the immobilized CE to be recycled 13 times through easy magnetic separation. The encapsulation of CE in silica nanospheres improved the efficiency of the enzymatic reactions by reducing the mass transfer limitation without any structural changes upon immobilization. This is the first demonstration of the co-encapsulation of MNPs and enzymes in mesoporous silica nanospheres to form stabilized and immobilized enzyme systems for biocatalytic applications.

Construction of a PEGDA/chitosan hydrogel incorporating mineralized copper-doped mesoporous silica nanospheres for accelerated bone regeneration

Hydrogels, integrating diverse biocompatible materials, have emerged as promising candidates for bone repair applications. This study presents a double network hydrogel designed for bone tissue engineering, combining poly(ethylene glycol) diacrylate (PEGDA) and chitosan (CS) crosslinked through UV polymerization and ionic crosslinking. Concurrently, copper-doped mesoporous silica nanospheres (Cu-MSNs) were synthesized using a one-pot method. Cu-MSNs underwent additional modification through in-situ biomineralization, resulting in the formation of an apatite layer. Polydopamine was employed to facilitate the deposition of Calcium (Ca) and Phosphate (P) ions on the surface of Cu-MSNs (Cu-MSNs/PDA@CaP). Composite hydrogels were created by integrating varied concentrations of Cu-MSNs/PDA@CaP (25, 50, 100, 150, 200 μg/mL). Characterization unveiled distinctive interconnected porous structures within the composite hydrogel, showcasing a notable 169.6 % enhancement in compressive stress (elevating from 89.01 to 240.19 kPa) compared to pure PEGDA. In vitro biocompatibility experiments illustrated that the composite hydrogel maintained elevated cell viability (up to 106.6 %) and facilitated rapid cell proliferation over 7 days. The hydrogel demonstrated a substantial 57.58 % rise in ALP expression and a surprising 235.27 % increase in ARS staining. Moreover, it significantly enhanced the expression of crucial osteogenic genes, such as run-related transcription factors 2 (RUNX2), collagen 1a1 (Col1a1), and secreted phosphoprotein 1 (Spp1), establishing it as a promising scaffold for bone regeneration. This study shows how Cu-MSNs/PDA@CaP were successfully integrated into a double network hydrogel, resulting in a composite material with good biological responses. Due to its improved characteristics, this composite hydrogel holds the potential for advancing bone regeneration procedures.

Tuning adsorption capacities of hybrid mesoporous silica nanospheres and adsorption mechanism study for sulfamethoxazole and diclofenac removal from water

The functionalization of mesoporous silica nanospheres and mesoporous hybrid core–shell magnetic silica nanospheres has been carried out through post-synthetic procedures, and these materials have been tested as adsorbents for the removal of sulfamethoxazole (SMX) and diclofenac (DF) from water. The effects of the silica material and the types of functionalities anchored on the silica surface have been investigated. Additionally, the unreacted silanol groups on the silica surface have been capped with hydrophobic trimethylsilyl groups to modify the hydrophilic-hydrophobic properties of the materials. The materials have been characterized by textural, spectroscopic, and microscopic techniques. The maximum adsorption capacity and kinetics of adsorption were determined using adsorption and kinetic theoretical models. The experimental results indicate that both the surface area and the presence of specific functionalities on the silica surface, including zwitterionic groups like hydroxide choline and methyl p-toluene sulfonate choline, have a significant impact on the material's adsorption capacity. The adsorption studies revealed that the highest adsorption capacity (qt) for DF (80.7 mg L-1) and SMX (27.2 mg L-1) was achieved with PTS-Chol-MSN, which consists of mesoporous silica nanospheres possessing a larger surface area, unprotected silanol groups and the methyl p-toluene sulfonate choline functionality on its surface. The mechanism of drug adsorption involves physical and chemical adsorptions with the presence of H-bonding and π-π stacking interactions.

PH-responsive upconversion mesoporous silica nanospheres for combined multimodal diagnostic imaging and targeted photodynamic and photothermal cancer therapy

pH-responsive upconversion mesoporous silica nanospheres for combined multimodal diagnostic imaging and targeted photodynamic and photothermal cancer therapy

Immobilizing Pd nanoparticles on amine-functionalized yolk-shell mesoporous silica nanospheres for efficient H2 production from formic acid dehydrogenation

Ultrafine Pd nanoparticles (NPs), immobilized within amine-functionalized yolk-shell mesoporous silica nanospheres (YSMSNs), have been elaborately prepared to facilitate the highly effective formic acid (FA) dehydrogenation. The optimized Pd/YSMSNs-NH2(10–3, 10 wt% Pd loading and 3 mL of amine treatment on YSMSNs), displays the extraordinary turnover frequency (TOF, 9108 h-1) and stability at 343 K, achieving 100% FA conversion and H2 selectivity, which is higher than other documented heterogeneous catalysts. The radially oriented pore channels can facilitate the mass transfer of reactants. The amine groups on the YSMSNs-NH2 effectively promote the cleavage of the O-H bond within FA. Furthermore, the ultrafine size of the Pd NPs and their high dispersion on the YSMSNs-NH2 provide a wealth of active sites for catalysis. Lastly, the metal-support interaction (MSI) between the Pd NPs and YSMSNs-NH2 further enhances the catalytic performance. This work provides a new strategy into developing effective silica-based heterogeneous catalysts for FA dehydrogenation.

Lignin/mesoporous hollow silica nanosphere thin film nanocomposite loose nanofiltration membrane for dye/salt separation

It has been still expected to explore a green and low-cost raw material for fabricating high performance loose nanofiltration (LNF) membrane with high permeance and dye/salt selectivity. In this report, aminated mesoporous hollow silica (AHS) nanospheres are first synthesized. Then, a lignin-based LNF membrane is fabricated employing aminated lignin as raw material, trimesoyl chloride as a crosslinker, and AHS nanospheres as nano additives by interfacial polymerization. It shows excellent pure water permeance, high dye rejection, and salt permeation. After being modified with L-arginine, the PWP (49.9 LMH bar−1) and salt permeation are further improved. Simultaneously, the dye rejections are kept at a high level. The AHS nanospheres provided abundant water/salt diffusion channels for the lignin-based separation layer. The hollow structure of the nanospheres decreases the diffusion resistance of the water and salt. Moreover, the membrane shows satisfactory structural and separation performance stability during immersion in acid and/or alkaline solutions. After being treated with 5500 ppm h chlorination strength, it still exhibits excellent BBR/NaCl selectivity accompanied by a small permeance increase. Furthermore, the membrane shows excellent fouling resistances, satisfactory bactericidal (92.5 %) and bacterial anti-adhesion properties. The membrane shows excellent performance stability in a long-term (80 h) dye/salt separation process.

Octadecyl-fibrous mesoporous silica nanospheres coated 96-blade thin-film microextraction for high-throughput analysis of phthalic acid esters in food and migration from food packages

A high-throughput sample pre-treatment method combined with high-performance liquid chromatography (HPLC) was developed to analyze phthalates (PAEs) in food and food contact package samples. Thin film microextraction (TFME) in 96-blade format was used to pre-treat 96 samples simultaneously. Octadecyl groups functionalized fibrous mesoporous silica nanospheres, namely C18-FMSNs, were synthesized and used as TFME coating material. The coating was fabricated by spraying a slurry of C18-FMSNs and polyacrylontrile (PAN) mixture with a commercial portable spraypen. The prepared C18-FMSNs/PAN coatings exhibited good reproducibility, repeatability and reusability. The optimized TFME conditions for PAEs consisted of extraction at pH 4.0 for 50 min, and desorption by methanol/acetonitrile (25/75, V/V) for 40 min. The pretreatment time for each sample was approximately 1.3 min. This TFME-HPLC method showed good linearity for eight PAEs within the concentration range of 0.5–1000 ng mL−1, with the coefficients higher than 0.9972. The limits of detection and quantification were 0.096–0.26 ng mL−1 and 0.32–0.86 ng mL−1, respectively. The intra-day and inter-day RSD % were below 6.6 % and 8.4 %, respectively, indicating good precision. The PAEs analysis in real samples showed that dibutyl phthalate (DBP) of 2.3 ± 0.3 ng mL−1 and di-(2-ethylhexyl) phthalate (DEHP) of 5.5 ± 0.8 ng mL−1 in boxed milk, dimethyl phthalate (DMP) of 12.6 ± 0.8 ng mL−1, DBP of 3.2 ± 0.4 ng mL−1and DEHP of 14.3 ± 0.7 ng mL−1 in the simulated water migration of plastic box, as well as DMP of 19.0 ± 0.6 ng mL−1, DBP of 25.6 ± 0.9 ng mL−1 and DEHP of 49.5 ± 2.8 ng mL−1 in the simulated ethanol migration of plastic box were determined, respectively. In addition, the detection of PAEs in all the real samples showed good recovery ranging from 85.6 to 110 % and lower RSDs % (<7.2 %).

Development of dual-channel fluorescent mesoporous SiO2 nanosphere-coated yttrium aluminum garnet composites for sensitive detection of latent fingerprints.

In this study, we investigated the detection of latent fingerprints (LFPs) using green light- and near-infrared (NIR) light-induced up/down-conversion dual-channel composites. Upconverted yttrium aluminium garnet (YAG) was prepared using a citric acid-assisted sol-gel method. After loading rhodamine 6G (RhD-6) into mesoporous silica nanospheres (MSNs), the MSNs-RhD-6 composites were coated with the as-synthesised YAG via electrostatic adsorption using the layer-by-layer method, demonstrating reversible switching between yellow and green light waves under 525 nm green light or 980 nm laser excitation. To evaluate the effectiveness of YAG-MSNs-RhD-6 powder in criminal investigations, we conducted simulations for different fingerprint scenarios. The results indicated that even after prolonged aging (up to 20 days), exposure to water, or high-temperature baking, the fingerprints remained clearly visible in the images. The detection of LFPs on various substrate surfaces exhibited high contrast, with the details of the fingerprints easily observable even after appropriate magnification. This study opens a new path for green light- and near-infrared light-induced up/down-conversion dual-channel composites for optical applications.

Enhanced Selective Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol over Silica-Coated Pt-CoxOy Hybrid Nanoparticles.

Selective hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL) is difficult due to the intrinsic difficulty with thermodynamically easier hydrogenation of C═C bonds. In this work, Pt-CoxOy hybrid nanoparticles encapsulated in mesoporous silica nanospheres (Pt-CoxOy@mSiO2) were synthesized by a sol-gel method, which showed greatly improved COL selectivity for hydrogenation of CAL. At 80 °C and 1.0 MPa of H2, Pt-CoxOy@mSiO2 achieved a CAL conversion of 98.7% with a COL selectivity of 93.5%. In contrast, Pt@mSiO2 yields 3-phenylpropanol (HCOL) as the major product with HCOL selectivity of 67.2%, while PtCo@mSiO2 yields 3-phenylpropionaldehyde with selectivity of 51.8% under the same conditions. The enhanced catalytic performance of Pt-CoxOy@mSiO2 for hydrogenation of CAL to COL is ascribed to the Pt surface electron deficiency induced by metal-oxide interaction, and the protection of active NPs by silica shells results in good catalytic stability.

CO2 hydrogenation to methanol over PdZn catalysts on bimetallic modified dendritic mesoporous silica nanospheres

Catalysts with the CeTi bimetallic modified dendritic mesoporous silica nanospheres (CTD) as supports, and the PdZn as active metal phase, PdZn/CTD catalysts with higher Pd metal dispersion and more oxygen vacancies were synthesized for efficient CO2 hydrogenation to methanol (MeOH). The modification of PdZn/CTD using CeTi metals can increase the dispersion of PdZn and improve the Ce3+/Ce4+ ratios. Higher active metal dispersion of PdZn/CTD catalyst is conducive to more H2 adsorption and to the expose of activation sites. Higher Ce3+/Ce4+ ratio of PdZn/CTD is beneficial to generate more oxygen vacancies, which can adsorb and activate CO2 molecules efficiently. The optimized PdZn/CTD catalysts exhibit superior CO2 conversion (33.6 %), MeOH selectivity (32.9 %), MeOH yield (11.1 %), TOF value (22.5 h−1), space–time yield (STY) (4.44 molMeOH kg-1 h−1) and 100 h long-term stability. Besides, through in-situ DRIFTS, HCOO* and CH3O* species are found to be the primary intermediates of the CO2 hydrogenation to MeOH reaction over the PdZn/CTD catalysts.

PH-Responsive Upconversion Mesoporous Silica Nanospheres for Combined Multimodal Diagnostic Imaging and Targeted Photodynamic and Photothermal Cancer Therapy.

Photodynamic therapy (PDT) and photothermal therapy (PTT) have gained considerable attention as potential alternatives to conventional cancer treatments. However, these approaches remain limited by low solubility, poor stability, and inefficient targeting of many common photosensitizers (PSs) and photothermal agents (PTAs). To overcome the aforementioned limitations, we engineered biocompatible and biodegradable tumor-targeted upconversion nanospheres with imaging capabilities. The multifunctional nanospheres consist of a sodium yttrium fluoride core doped with lanthanides (ytterbium, erbium, and gadolinium) and the PTA bismuth selenide (NaYF4:Yb/Er/Gd,Bi2Se3) enveloped in a mesoporous silica shell that encapsulates a PS, chlorin e6 (Ce6), within its pores. NaYF4:Yb/Er converts deeply penetrating near-infrared (NIR) light to visible light, which excites Ce6 to generate cytotoxic reactive oxygen species (ROS), while Bi2Se3 efficiently converts absorbed NIR light to heat. Additionally, Gd enables magnetic resonance imaging of the nanospheres. The mesoporous silica shell is coated with DPPC/cholesterol/DSPE-PEG to retain the encapsulated Ce6 and prevent serum protein adsorption and macrophage recognition that hinder tumor targeting. Finally, the coat is conjugated to the acidity-triggered rational membrane (ATRAM) peptide, which promotes specific and efficient internalization into malignant cells in the mildly acidic microenvironment of tumors. The nanospheres facilitated tumor magnetic resonance and thermal and fluorescence imaging and exhibited potent NIR laser light-induced anticancer effects in vitro and in vivo via combined ROS production and localized hyperthermia, with negligible toxicity to healthy tissue, hence markedly extending survival. Our results demonstrate that the ATRAM-functionalized, lipid/PEG-coated upconversion mesoporous silica nanospheres (ALUMSNs) offer multimodal diagnostic imaging and targeted combinatorial cancer therapy.

Dendritic micro-mesoporous composites via nano-assembly strategy towards high-efficiency catalysts for hydrodesulfurization of dibenzothiophenes

Based on the three-dimensional center-radial framework structure of dendritic mesoporous silica nanospheres (DMSNs), a unique type of hierarchical micro-mesoporous composite material, namely, Beta-DMSNs (BD) was prepared through a nano-assembly method, which was utilized as superior supports for high-efficiency catalysts (NiMo/BD) for hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The controllable introduction of Beta nanocrystals endows the NiMo/BD catalysts with more acidic and catalytic active sites, and shows no influence on the dendritic morphology of the mesoporous supports, resulting in the remarkable HDS performance of NiMo/BD catalysts. Owing to the dendritic open channels, high surface area, abundant acidic sites and highly dispersed MoS2 active phases, the optimized NiMo/BD exhibited superior HDS activities of 99.1% and 98.3% for DBT and 4,6-DMDBT, respectively, with the optimal reaction rate constant of 3.0 × 10−7 mol g−1 s−1 and 2.4 × 10−7 mol g−1 s−1, and with the turnover frequency of 5.9 × 10−4 s−1 and 4.8 × 10−4 s−1. Besides, the enhanced Brønsted acid and the synergistic effect of Brønsted & Lewis acid contributed to the superior isomerization selectivity for 4,6-DMDBT, which was conducive to its HDS.