Search Results (49)

Mesoporous ZnO/ZnCo₂O₄ nanocomposites with excellent gas-sensing performance were synthesized using the Ostwald ripening method. The as-prepared ZnO/ZnCo₂O₄ comprised aggregated monodisperse nanoparticles, and the nanoparticle size grew with increasing thermal treatment temperature. Increasing the calcination temperature did not significantly change the overall size of the ZnO/ZnCo₂O₄ nanocomposites, but the pore size and specific surface area were noticeably affected. The gas-sensing results showed that ZnO/ZnCo₂O₄ composites calcined at 500 °C exhibited the highest response to H₂S at 200 °C, with a detection limit of 500 ppb. The ZnO/ZnCo₂O₄ composites also exhibited remarkable selectivity, response/recovery speed, and stability. Their excellent gas-sensing performance might be attributed to their porous structure, large specific surface area, and the heterogeneous interface between ZnO and ZnCo₂O₄. This work not only represents a new example of the Ostwald ripening-based formation of inorganic hollow structures in a template-free aqueous solution but also provides a novel and efficient sensing material for the detection of H₂S gas. Full article

β-cypermethrin (BCP) is a broad-spectrum insecticide known for its rapid efficacy. However, it is highly toxic to non-target organisms such as bees and fish, and its effectiveness is limited by a short duration of action. Improving the release profile of BCP is essential for reducing its environmental toxicity while preserving its effectiveness. In this study, hollow mesoporous silica nanoparticles (HMSNs) were synthesized using a self-templating method, and BCP-loaded HMSNs were prepared through physical adsorption. The structural and physicochemical properties of the nanoparticles were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption–desorption analysis, Fourier transform infrared (FT-IR) spectroscopy, dynamic light scattering (DLS), and thermogravimetric analysis (TGA). The BCP release profile was assessed using the dialysis bag method. The results showed that the synthesized nanoparticles exhibited uniform morphology, thin shells, and large internal cavities. The HMSNs had a pore size of 3.09 nm, a specific surface area of 1318 m²·g⁻¹, a pore volume of 1.52 cm³·g⁻¹, and an average particle size of 183 nm. TEM, FT-IR, and TGA analyses confirmed the successful incorporation of BCP into the HMSNs, achieving a drug loading efficiency of 32.53%. The BCP-loaded nanoparticles exhibited sustained-release properties, with an initial burst followed by gradual release, extending efficacy for 30 days. Safety evaluations revealed minimal toxicity to maize seedlings, confirming the biocompatibility of the nanoparticles. These findings indicate that BCP-loaded HMSNs can enhance the efficacy of BCP while reducing its environmental toxicity, providing a biocompatible and environmentally friendly solution for pest control. Full article

Solar-driven catalytic oxidation processes for the removal of toxic gaseous pollutants have attracted considerable scientific attention, and there is a strong desire to improve the mass transfer, photogenerated charge separation, and O₂ activation by regulating the structure of the photocatalyst. Initially, functionalized graphene–TiO₂ mesoporous hollow nanofibers have been controllably fabricated by a coaxial electrospinning technique, in which functionalized graphene is controllably prepared through a sequential diazonium functionalization and silane modification and ensures its uniform distribution among TiO₂ nanoparticles (NPs). Subsequently, the ultrafine Ag NPs are primarily anchored onto the surface of graphene by an in situ frozen photodeposition strategy, producing Ag/functionalized graphene–TiO₂ mesoporous hollow nanofibers (Ag/SiG-TO MPHNFs). The optimal Ag/SiG-TO MPHNFs exhibit 3.9-fold and 4.6-fold enhancements in CO photooxidation compared with TO MPHNFs and P25 TiO₂, respectively. The enhanced photoactivity can be attributed to three factors: the creation of the mesoporous hollow structure accelerates mass transfer, the incorporation of graphene facilitates the transfer of photogenerated electrons from TiO₂ to graphene, and the anchoring of Ag NPs improves O₂ activation. Full article

Converting carbon dioxide (CO₂) into solar fuels through photocatalysis represents an appealing approach to tackling the escalating energy crisis and mitigating the greenhouse effect. In this study, using melamine–formaldehyde (MF) nanospheres as a nitrogen source, a N element was simultaneously doped into the TiO₂ nanoparticle structure supported by carbon hollow spheres using a one-step carbonization method to form a heterojunction N-CHS@N-TiO₂ (marked as (N-(CHS@TiO₂)). The composite showed superior photocatalytic activity in reducing CO₂ compared with TiO₂ and N-CHS: after 6 h of visible light irradiation, the CO yield was 4.3 times that of N-CHS and TiO₂; 6 h of UV irradiation later, the CO yield reached 2.6 times that of TiO₂ and 7 times that of N-CHS. The substantial enhancement in photocatalytic activity was attributed to the nitrogen simultaneously doped carbon hollow spheres and TiO₂, mesoporous structure, small average TiO₂ crystal size, large surface areas, and the heterostructure formed by N-CHS and N-TiO₂. The UV-vis diffuse reflectance spectra (DRS) exhibit a significant improvement in light absorption, attributed to the visible-light-active carbon hollow sphere and the N element doping, thereby enhancing solar energy utilization. Full article

Androgenetic alopecia (AGA) is caused by the impact of dihydrotestosterone (DHT) on hair follicles, leading to progressive hair loss in men and women. In this study, we developed caffeine-loaded hollow mesoporous silica nanoparticles coated with ultradeformable liposomes (ULp-Caf@HMSNs) to enhance caffeine delivery to hair follicles. Caffeine, known to inhibit DHT formation, faces challenges in skin penetration due to its hydrophilic nature. We investigated caffeine encapsulated in liposomes, hollow mesoporous silica nanoparticles (HMSNs), and ultradeformable liposome-coated HMSNs to optimize drug delivery and release. For ultradeformable liposomes (ULs), the amount of polysorbate 20 and polysorbate 80 was varied. TEM images confirmed the mesoporous shell and hollow core structure of HMSNs, with a shell thickness of 25–35 nm and a hollow space of 80–100 nm. SEM and TEM analysis showed particle sizes ranging from 140–160 nm. Thermal stability tests showed that HMSNs coated with ULs exhibited a Td₁₀ value of 325 °C and 70% residue ash, indicating good thermal stability. Caffeine release experiments indicated that the highest release occurred in caffeine-loaded HMSNs without a liposome coating. In contrast, systems incorporating ULp-Caf@HMSNs exhibited slower release rates, attributable to the dual encapsulation mechanism. Confocal laser scanning microscopy revealed that ULs-coated particles penetrated deeper into the skin than non-liposome particles. MTT assays confirmed the non-cytotoxicity of all HMSN concentrations to human follicle dermal papilla cells (HFDPCs). ULp-Caf@HMSNs promoted better cell viability than pure caffeine or caffeine-loaded HMSNs, highlighting enhanced biocompatibility without increased toxicity. Additionally, ULp-Caf@HMSNs effectively reduced ROS levels in DHT-damaged HFDPCs, suggesting they are promising alternatives to minoxidil for promoting hair follicle growth and reducing hair loss without increasing oxidative stress. This system shows promise for treating AGA. Full article

In agriculture, soil-borne fungal pathogens, especially Fusarium oxysporum strains, are posing a serious threat to efforts to achieve global food security. In the search for safer agrochemicals, silica nanoparticles (SiO₂NPs) have recently been proposed as a new tool to alleviate pathogen damage including Fusarium wilt. Hollow mesoporous silica nanoparticles (HMSNs), a unique class of SiO₂NPs, have been widely accepted as desirable carriers for pesticides. However, their roles in enhancing disease resistance in plants and the specific mechanism remain unknown. In this study, three sizes of HMSNs (19, 96, and 406 nm as HMSNs-19, HMSNs-96, and HMSNs-406, respectively) were synthesized and characterized to determine their effects on seed germination, seedling growth, and Fusarium oxysporum f. sp. phaseoli (FOP) suppression. The three HMSNs exhibited no side effects on cowpea seed germination and seedling growth at concentrations ranging from 100 to 1500 mg/L. The inhibitory effects of the three HMSNs on FOP mycelial growth were very weak, showing inhibition ratios of less than 20% even at 2000 mg/L. Foliar application of HMSNs, however, was demonstrated to reduce the FOP severity in cowpea roots in a size- and concentration-dependent manner. The three HMSNs at a low concentration of 100 mg/L, as well as HMSNs-19 at a high concentration of 1000 mg/L, were observed to have little effect on alleviating the disease incidence. HMSNs-406 were most effective at a concentration of 1000 mg/L, showing an up to 40.00% decline in the disease severity with significant growth-promoting effects on cowpea plants. Moreover, foliar application of HMSNs-406 (1000 mg/L) increased the salicylic acid (SA) content in cowpea roots by 4.3-fold, as well as the expression levels of SA marker genes of PR-1 (by 1.97-fold) and PR-5 (by 9.38-fold), and its receptor gene of NPR-1 (by 1.62-fold), as compared with the FOP infected control plants. Meanwhile, another resistance-related gene of PAL was also upregulated by 8.54-fold. Three defense-responsive enzymes of POD, PAL, and PPO were also involved in the HMSNs-enhanced disease resistance in cowpea roots, with varying degrees of reduction in activity. These results provide substantial evidence that HMSNs exert their Fusarium wilt suppression in cowpea plants by activating SA-dependent SAR (systemic acquired resistance) responses rather than directly suppressing FOP growth. Overall, for the first time, our results indicate a new role of HMSNs as a potent resistance inducer to serve as a low-cost, highly efficient, safe and sustainable alternative for plant disease protection. Full article

Despite recent clinical successes in cancer immunotherapy, it remains difficult to initiate a long-term anti-tumor effect. Therefore, repeated administrations of immune-activating agents are generally required in most cases. Herein, we propose an adjuvant particle size tuning strategy to initiate a long-term anti-tumor effect by one-shot vaccination. This strategy is based on the size-dependent immunostimulation mechanism of mesoporous silica particles. Hollow mesoporous silica (HMS) nanoparticles enhance the antigen uptake with dendritic cells around the immunization site in vivo. In contrast, hierarchically porous silica (HPS) microparticles prolong cancer antigen retention and release in vivo. The size tuning of the mesoporous silica adjuvant prepared by combining both nanoparticles and microparticles demonstrates the immunological properties of both components and has a long-term anti-tumor effect after one-shot vaccination. One-shot vaccination with HMS-HPS-ovalbumin (OVA)-Poly IC (PIC, a TLR3 agonist) increases CD4⁺ T cell, CD8⁺ T cell, and CD86⁺ cell populations in draining lymph nodes even 4 months after vaccination, as well as effector memory CD8⁺ T cell and tumor-specific tetramer⁺CD8⁺ T cell populations in splenocytes. The increases in the numbers of effector memory CD8⁺ T cells and tumor-specific tetramer⁺CD8⁺ T cells indicate that the one-shot vaccination with HMS-HPS-OVA-PIC achieved the longest survival time after a challenge with E.G7-OVA cells among all groups. The size tuning of the mesoporous silica adjuvant shows promise for one-shot vaccination that mimics multiple clinical vaccinations in future cancer immunoadjuvant development. This study may have important implications in the long-term vaccine design of one-shot vaccinations. Full article

Nanotechnology-enabled pesticide delivery systems have been widely studied and show great prospects in modern agriculture. Nanodelivery systems not only achieve the controlled release of agrochemicals but also possess many unique characteristics. This study presents the development of a pH-responsive pesticide nanoformulation utilizing hollow mesoporous silica nanoparticles (HMSNs) as a nanocarrier. The nanocarrier was loaded with the photosensitive pesticide prochloraz (Pro) and then combined with ZnO quantum dots (ZnO QDs) through electrostatic interactions. ZnO QDs serve as both the pH-responsive gatekeeper and the enhancer of the pesticide. The results demonstrate that the prepared nanopesticide exhibits high loading efficiency (24.96%) for Pro. Compared with Pro technical, the degradation rate of Pro loaded in HMSNs@Pro@ZnO QDs was reduced by 26.4% after 24 h ultraviolet (UV) exposure, indicating clearly improved photostability. In a weak acidic environment (pH 5.0), the accumulated release of the nanopesticide after 48 h was 2.67-fold higher than that in a neutral environment. This indicates the excellent pH-responsive characteristic of the nanopesticide. The tracking experiments revealed that HMSNs can be absorbed by rice leaves and subsequently transported to other tissues, indicating their potential for effective systemic distribution and targeted delivery. Furthermore, the bioactivity assays confirmed the fungicidal efficacy of the nanopesticide against rice blast disease. Therefore, the constructed nanopesticide holds great prospect in nanoenabled agriculture, offering a novel strategy to enhance pesticide utilization. Full article

The lignin-based mesoporous hollow carbon@MnO₂ nanosphere composites (L-C-NSs@MnO₂) were fabricated by using lignosulfonate as the carbon source. The nanostructured MnO₂ particles with a diameter of 10~20 nm were uniformly coated onto the surfaces of the hollow carbon nanospheres. The obtained L-C-NSs@MnO₂ nanosphere composite showed a prolonged cycling lifespan and excellent rate performance when utilized as an anode for LIBs. The L-C-NSs@MnO₂ nanocomposite (24.6 wt% of MnO₂) showed a specific discharge capacity of 478 mAh g⁻¹ after 500 discharge/charge cycles, and the capacity contribution of MnO₂ in the L-C-NSs@MnO₂ nanocomposite was estimated ca. 1268.8 mAh g⁻¹, corresponding to 103.2% of the theoretical capacity of MnO₂ (1230 mAh g⁻¹). Moreover, the capacity degradation rate was ca. 0.026% per cycle after long-term and high-rate Li⁺ insertion/extraction processes. The three-dimensional lignin-based carbon nanospheres played a crucial part in buffering the volumetric expansion and agglomeration of MnO₂ nanoparticles during the discharge/charge processes. Furthermore, the large specific surface areas and mesoporous structure properties of the hollow carbon nanospheres significantly facilitate the fast transport of the lithium-ion and electrons, improving the electrochemical activities of the L-C-NSs@MnO₂ electrodes. The presented work shows that the combination of specific structured lignin-based carbon nanoarchitecture with MnO₂ provides a brand-new thought for the designation and synthesis of high-performance materials for energy-related applications. Full article

Mixed matrix membranes (MMMs) have shown great potential in pervaporation (PV). As for many novel membrane materials however, lab-scale testing often involves synthetic feed solutions composed of mixed pure components, overlooking the possibly complex interactions and effects caused by the numerous other components in a real PV feed. This work studies the performance of MMMs with two different types of fillers, a core-shell material consisting of ZIF-8 coated on mesoporous silica and a hollow sphere of silicalite-1, in the PV of a real fermented wheat/hay straw hydrolysate broth for the production of bio-ethanol. All membranes, including a reference unfilled PDMS, show a declining permeability over time. Interestingly, the unfilled PDMS membrane maintains a stable separation factor, whereas the filled PDMS membranes rapidly lose selectivity to levels below that of the reference PDMS membrane. A membrane autopsy using XRD and SEM-EDX revealed an almost complete degradation of the crystalline ZIF-8 in the MMMs. Reference experiments with ZIF-8 nanoparticles in the fermentation broth demonstrated the influence of the broth on the ZIF-8 particles. However, the observed effects from the membrane autopsy could not exactly be replicated, likely due to distinct differences in conditions between the in-situ pervaporation process and the ex-situ reference experiments. These findings raise significant questions regarding the potential applicability of MOF-filled MMMs in real-feed pervaporation processes and, potentially, in harsh condition membrane separations in general. This study clearly confirms the importance of testing membranes in realistic conditions. Full article

High activity of a catalyst and its thermal stability over a lifetime are essential for catalytic applications, including catalytic gas sensors. Highly porous materials are attractive to support metal catalysts because they can carry a large quantity of well-dispersed metal nanoparticles, which are well-accessible for reactants. The present work investigates the long-term stability of mesoporous Co₃O₄-supported Au–Pd catalyst (Au–Pd@meso-Co₃O₄), with a metal loading of 7.5 wt% and catalytically active mesoporous Co₃O₄ (meso-Co₃O₄) for use in catalytic gas sensors. Both catalysts were characterized concerning their sensor response towards different concentrations of methane and propane (0.05–1%) at operating temperatures ranging from 200 °C to 400 °C for a duration of 400 h. The initially high sensor response of Au–Pd@meso-Co₃O₄ to methane and propane decreased significantly after a long-term operation, while the sensor response of meso-Co₃O₄ without metallic catalyst was less affected. Electron microscopy studies revealed that the hollow mesoporous structure of the Co₃O₄ support is lost in the presence of Au–Pd particles. Additionally, Ostwald ripening of Au–Pd nanoparticles was observed. The morphology of pure meso-Co₃O₄ was less altered. The low thermodynamical stability of mesoporous structure and low phase transformation temperature of Co₃O₄, as well as high metal loading, are parameters influencing the accelerated sintering and deactivation of Au–Pd@meso-Co₃O₄ catalyst. Despite its high catalytic activity, Au–Pd@meso-Co₃O₄ is not long-term stable at increased operating temperatures and is thus not well-suited for gas sensors. Full article

TiO₂ and core–shell SiO₂@TiO₂ nanoparticles were synthesized by sol-gel process at different calcination temperatures. Mesoporous hollow TiO₂ composites were prepared by etching SiO₂ from SiO₂@TiO₂ nanoparticles with alkali solution. X-ray diffraction (XRD), Scanning electron microscope (SEM),Transmission electron microscope (TEM), and N₂ adsorption–desorption isotherms, and Roman and Diffuse reflectance spectroscopy (DRS) were employed to characterize the synthesized materials. The effects of different calcination temperatures on the morphology, crystallinity, phase composition, and photocatalytic activity of the prepared materials were investigated in detail. It was found that the calcination temperature altered the phase structure, crystallinity, morphology, specific surface area, and porous structure. Additionally, it was verified that SiO₂ could inhibit the transfer of TiO₂ from anatase phase to rutile phase under high temperature calcination (850 °C). The hollow TiO₂ calcined at 850 °C showed the highest photocatalytic efficiency of 97.5% for phenol degradation under UV irradiation. Full article

In this study, we synthesized hollow mesoporous silica nanoparticles (HMSNs) coated with polydopamine (PDA) and a D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS)-modified hybrid lipid membrane (denoted as HMSNs-PDA@liposome-TPGS) to load doxorubicin (DOX), which achieved the integration of chemotherapy and photothermal therapy (PTT). Dynamic light scattering (DLS), transmission electron microscopy (TEM), N₂ adsorption/desorption, Fourier transform infrared spectrometry (FT-IR), and small-angle X-ray scattering (SAXS) were used to show the successful fabrication of the nanocarrier. Simultaneously, in vitro drug release experiments showed the pH/NIR-laser-triggered DOX release profiles, which could enhance the synergistic therapeutic anticancer effect. Hemolysis tests, non-specific protein adsorption tests, and in vivo pharmacokinetics studies exhibited that the HMSNs-PDA@liposome-TPGS had a prolonged blood circulation time and greater hemocompatibility compared with HMSNs-PDA. Cellular uptake experiments demonstrated that HMSNs-PDA@liposome-TPGS had a high cellular uptake efficiency. In vitro and in vivo antitumor efficiency evaluations showed that the HMSNs-PDA@liposome-TPGS + NIR group had a desirable inhibitory activity on tumor growth. In conclusion, HMSNs-PDA@liposome-TPGS successfully achieved the synergistic combination of chemotherapy and photothermal therapy, and is expected to become one of the candidates for the combination of photothermal therapy and chemotherapy antitumor strategies. Full article

Silica nanoparticles (SNPs) have shown promise in biomedical applications such as drug delivery and imaging due to their versatile synthetic methods, tunable physicochemical properties, and ability to load both hydrophilic and hydrophobic cargo with high efficiency. To improve the utility of these nanostructures, there is a need to control the degradation profile relative to specific microenvironments. The design of such nanostructures for controlled combination drug delivery would benefit from minimizing degradation and cargo release in circulation while increasing intracellular biodegradation. Herein, we fabricated two types of layer-by-layer hollow mesoporous SNPs (HMSNPs) containing two and three layers with variations in disulfide precursor ratios. These disulfide bonds are redox-sensitive, resulting in a controllable degradation profile relative to the number of disulfide bonds present. Particles were characterized for morphology, size and size distribution, atomic composition, pore structure, and surface area. No difference was observed between in vitro cytotoxicity profiles of the fabricated nanoparticles at 24 h in the concentration range below 100 µg mL⁻¹. The degradation profiles of particles were evaluated in simulated body fluid in the presence of glutathione. The results demonstrate that the composition and number of layers influence degradation rates, and particles containing a higher number of disulfide bridges were more responsive to enzymatic degradation. These results indicate the potential utility of layer-by-layer HMSNPs for delivery applications where tunable degradation is desired. Full article

Controlling the particle size as well as porosity and shape of silica nanoparticles is always a big challenge while tuning their properties. Here, we designed a cost-effective, novel, green synthetic method for the preparation of perforated hollow mesoporous silica nanoparticles (PHMS-1) using a very minute amount of cationic surfactant in o/w-type (castor oil in water) emulsion at room temperature. The grafting of Al(III) through post-synthetic modification onto this silica framework (PHMS-2, Si/Al ~20 atomic percentage) makes this a very efficient solid acid catalyst for the conversion of monosaccharides to 5-HMF. Brunauer–Emmett–Teller (BET) surface area for the pure silica and Al-doped mesoporous silica nanoparticles (MSNs) were found to be 866 and 660 m²g⁻¹, respectively. Powder XRD, BET and TEM images confirm the mesoporosity of these materials. Again, the perforated hollow morphology was investigated using scanning electron microscopic analysis. Al-doped hollow MSNs were tested for acid catalytic-biomass conversion reactions. Our results show that PHMS-2 has much higher catalytic efficiency than contemporary aluminosilicate frameworks (83.7% of 5-HMF yield in 25 min at 160 °C for fructose under microwave irradiation). Full article