Mesoporous Silica Nanomaterials Research Articles

Bone‐Targeting and Multishelled Oral Eldecalcitol Nanoparticles Improve Osteoporosis by Reconstruction of Osteogenic‐Osteoclastic Homeostasis

AbstractCurrent treatment of postmenopausal osteoporosis (PMOP) focuses on systemic administration of medication, neglecting to proactively modulate the local microenvironment of skeletal system for superior therapeutic performance. Eldecalcitol (ED‐71), a novel drug for treating osteoporosis, still requires research to overcome high‐frequency delivery and low‐utilization. Here, a bone‐targeting and multishelled nanoparticles are developed for step‐wise release of ED‐71. The nanoparticles are achieved by using the chitosan/alginate outer layer as protective barrier against gastric acid, pectin middle layer as adhesive agent that improved intestinal penetration, and ethylene diamine tetraacetic acid‐grafted mesoporous silica nanomaterials core as bone‐targeting nanocarriers. After oral administration, the ED‐71‐loaded nanoparticles (ME‐ED‐71@PCA) promotes osteogenic differentiation of bone marrow mesenchymal stem cells by reducing intracellular oxidative stress, and inhibits the osteoclast differentiation. ME‐ED‐71@PCA improves bone mass in ovariectomized‐mice by promoting osteogenesis and inhibiting osteoclastogenesis, and the efficacy is more pronounced than ED‐71 alone. ME‐ED‐71@PCA exhibits satisfactory therapeutic performance due to its step‐wise drug release and bone‐targeting compared to ED‐71 administration, providing a new approach to re‐establish bone metabolic homeostasis in PMOP.

Multifunctional Nanocarrier for Synergistic Treatment of Alzheimer's Disease by Inhibiting β-Amyloid Aggregation and Scavenging Reactive Oxygen Species.

The excessive depositions of β-amyloid (Aβ) and abnormal level of reactive oxygen species (ROS) are considered as the important pathogenic factors of Alzheimer's disease (AD). Strategies targeting only one of them have no obvious effects in clinic. In this study, a multifunctional nanocarrier CICe@M-K that crosses the blood-brain barrier (BBB) efficiently was developed for inhibiting Aβ aggregation and scavenging ROS synchronously. Antioxidant curcumin (Cur) and photosensitizer IR780 were loaded in mesoporous silica nanomaterials (MSNs). Their surfaces were grafted with cerium oxide nanoparticles (CeO2 NPs) and a short peptide K (CKLVFFAED). Living imaging showed that CICe@M-K was mainly distributed in the brain, liver, and kidneys, indicating CICe@M-K crossed BBB efficiently and accumulated in brain. After the irradiation of 808 nm laser, Cur was continuously released. Both of Cur and the peptide K can recognize and bind to Aβ through multiple interaction including π-π stacking interaction, hydrophobic interaction, and hydrogen bond, inhibiting Aβ aggregation. On the other hand, Cur and CeO2 NPs cooperate to relieve the oxidative stress in the brains by scavenging ROS. In vivo assays showed that the CICe@M-K could diminish Aβ depositions, alleviate oxidative stress, and improve cognitive ability of the APP/PS1 AD mouse model, which demonstrated that CICe@M-K is a potential agent for AD treatment.

Hard tissue formation in pulpotomized primary teeth in dogs with nanomaterials MCM-48 and MCM-48/hydroxyapatite: an in vivo animal study

BackgroundThis animal study sought to evaluate two novel nanomaterials for pulpotomy of primary teeth and assess the short-term pulpal response and hard tissue formation in dogs. The results were compared with mineral trioxide aggregate (MTA).MethodsThis in vivo animal study on dogs evaluated 48 primary premolar teeth of 4 mongrel female dogs the age of 6–8 weeks, randomly divided into four groups (n = 12). The teeth underwent complete pulpotomy under general anesthesia. The pulp tissue was capped with MCM-48, MCM-48/Hydroxyapatite (HA), MTA (positive control), and gutta-percha (negative control), and the teeth were restored with intermediate restorative material (IRM) paste and amalgam. After 4–6 weeks, the teeth were extracted and histologically analyzed to assess the pulpal response to the pulpotomy agent.ResultsThe data were analyzed using the Kruskal‒Wallis, Fisher’s exact, Spearman’s, and Mann‒Whitney tests. The four groups were not significantly different regarding the severity of inflammation (P = 0.53), extent of inflammation (P = 0.72), necrosis (P = 0.361), severity of edema (P = 0.52), extent of edema (P = 0.06), or connective tissue formation (P = 0.064). A significant correlation was noted between the severity and extent of inflammation (r = 0.954, P < 0.001). The four groups were significantly different regarding the frequency of bone formation (P = 0.012), extent of connective tissue formation (P = 0.047), severity of congestion (P = 0.02), and extent of congestion (P = 0.01). No bone formation was noted in the gutta-percha group. The type of newly formed bone was not significantly different among the three experimental groups (P = 0.320).ConclusionMCM-48 and MCM-48/HA are bioactive nanomaterials that may serve as alternatives for pulpotomy of primary teeth due to their ability to induce hard tissue formation. The MCM-48 and MCM-48/HA mesoporous silica nanomaterials have the potential to induce osteogenesis and tertiary (reparative) dentin formation.

Mesoporous Silica Nanomaterials Targeted Delivery of PDK Inhibitor and shRNA Dual Therapy for Osteosarcoma Inhibitory Activity and Mechanism

Mesoporous Silica Nanomaterials Targeted Delivery of PDK Inhibitor and shRNA Dual Therapy for Osteosarcoma Inhibitory Activity and Mechanism

Exploring the Synergy between Nano-Formulated Linezolid and Polymyxin B as a Gram-Negative Effective Antibiotic Delivery System Based on Mesoporous Silica Nanoparticles.

Antimicrobial resistance is a current silent pandemic that needs new types of antimicrobial agents different from the classic antibiotics that are known to lose efficiency over time. Encapsulation of antibiotics inside nano-delivery systems could be a promising, effective strategy that is able to delay the capability of pathogens to develop resistance mechanisms against antimicrobials. These systems can be adapted to deliver already discovered antibiotics to specific infection sites in a more successful way. Herein, mesoporous silica nanomaterials are used for an efficient delivery of a linezolid gram-positive antibiotic that acts synergistically with gram-negative antimicrobial polymyxin B. For this purpose, linezolid is encapsulated in the pores of the mesoporous silica, whose outer surface is coated with a polymyxin B membrane disruptor. The nanomaterial showed a good controlled-release performance in the presence of lipopolysaccharide, found in bacteria cell membranes, and the complete bacteria E. coli DH5α. The performed studies demonstrate that when the novel formulation is near bacteria, polymyxin B interacts with the cell membrane, thereby promoting its permeation. After this step, linezolid can easily penetrate the bacteria and act with efficacy to kill the microorganism. The nano-delivery system presents a highly increased antimicrobial efficacy against gram-negative bacteria, where the use of free linezolid is not effective, with a fractional inhibitory concentration index of 0.0063 for E. coli. Moreover, enhanced toxicity against gram-positive bacteria was confirmed thanks to the combination of both antibiotics in the same nanoparticles. Although this new nanomaterial should be further studied to reach clinical practice, the obtained results pave the way to the development of new nanoformulations which could help in the fight against bacterial infections.

Intra-articular injection of stigmasterol-loaded nanoparticles reduce pain and inhibit the inflammation and joint destruction in osteoarthritis rat model: A pilot study.

Stigmasterol, a plant-derived sterol, sharing structural similarity with cholesterol, has demonstrated anti-osteoarthritis (OA) properties, attributed to its antioxidant and anti-inflammatory capabilities. Given that OA often arises in weight bearing or overused joints, prolonged localized treatment effectively targets inflammatory aspects of the disease. This research explored the impact of stigmasterol-loaded nanoparticles delivered via intra-articular injections in an OA rat model. Employing mesoporous silica nanomaterials (MSNs) combined with β-cyclodextrin (β-CD) as a vehicle, stigmasterol was loaded in conjunction with tannic acid, forming stigmasterol/β-CD-MSNs to facilitate a sustained stigmasterol release. The study employed RAW 264.7 cells to examine the in vitro cytotoxicity and anti-inflammatory effect of stigmasterol/β-CD-MSNs. For in vivo experimentation, we used healthy control rats and monosodium iodoacetate (MIA)-induced OA rats, separated into five groups, varying the injection substances. In vitro findings indicated that stigmasterol/β-CD-MSNs suppressed the mRNA expression of key pro-inflammatory mediators such as interleukin-6, tumor necrosis factor-α, and matrix metalloproteinase-3 in a dose-dependent manner. In vivo experiments revealed a substantial decrease in the mRNA levels of pro-inflammatory factors in the stigmasterol(50µg)/β-CD-MSN group compared to the others. Macroscopic, radiographic, and histological evaluations established that intra-articular injections of stigmasterol/β-CD-MSNs inhibited cartilage degeneration and subchondral bone deterioration. Therefore, in a chemically induced OA rat model, intra-articular stigmasterol delivery was associated with reduction in both local and systemic inflammatory responses, alongside a slowdown in joint degradation and arthritic progression.

Physicochemical and textural properties of amino-functionalised mesoporous silica nanomaterials from different silica sources

A series of MCM-41 nanomaterials that could serve various scientific applications was synthesised from two silica sources, tetraethyl ortho silicate and sodium silicate. Calcination and solvent extraction were employed as surfactant removal methods, while surface functionalisation was done via co-condensation and post-grafting methods. The synthesised nanomaterials were characterised, and their physicochemical properties were compared using X-ray powder diffraction (XRD), Brunauer Emmett Teller (BET) analysis, Fourier Transform Infra-red spectroscopy (FTIR), Thermogravimetric analysis (TGA), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The results showed that the surfactant removal and surface functionalisation methods affected the synthesised nanomaterials' 2θ values, d-spacing, and unit cell parameters. However, surfactant removal methods did not affect the morphology of amino-functionalised nanomaterials. Mesoporous silica nanomaterials of specific surface areas (884.0–17.1 m2/g), pore volumes (1.0–0.1 cm3/g), pore size diameters (7.2–1.5 nm), and less orderly mesoporous structures were produced with co-condensation and amino functionalisation using both silica sources. These methods can produce mesoporous silica nanostructures with different morphologies for wastewater remediation, catalysis, bio-catalysis, drug delivery, CO2 capture, indoor air cleaning, bioanalytical sample preparation, and pervaporation membrane improvement.

Molecular Characterization of Mesoporous Silica (Un)loading by Gemcitabine and Ibuprofen – An Interplay of Salt-Bridges and Hydrogen Bonds

The molecular mechanisms of mesoporous silica nanomaterial (MSN) loading by gemcitabine and ibuprofen molecules, respectively, are elucidated as functions of pore geometry. Based on a small series of MSN archetypes, we use molecular dynamics simulations to systematically explore molecule-by-molecule loading of the carrier material. Apart from predicting the maximum active pharmaceutical ingredient (API) loading capacity, more detailed statistical analysis of the incorporation energy reveals dedicated profiles stemming from the interplay of guest-MSN salt-bridges/hydrogen bonding in concave and convex domains of the silica surfaces - which outcompete interactions among the drug molecules. Only after full coverage of the silica surface, we find secondary layer growth stabilized by guest-guest interactions exclusively. Based on molecular models, we thus outline a two-step type profile for drug release from MSN networks. Subject to the MSN structure, we find 50–75 % of the API within amorphous domains in the inner regions of the pores – from which drug release is provided at constant dissociation energy. In turn, the remaining 50–25 % of drug molecules are drastically hindered from dissociation.

Atrazine Degradation Using Immobilized Triazine Hydrolase from Arthrobacter aurescens TC1 in Mesoporous Silica Nanomaterials.

Triazine hydrolase fromArthrobacter aurescens TC1 (TrzN) was successfully immobilized on mesoporous silica nanomaterials (MSNs) for the first time. For both nonfunctionalized MSNs and MSNs functionalized with Zn(II), three pore sizes were evaluated for their ability to immobilize wild-type TrzN: Mobile composition of matter no. 41 (small, 3 nm pores), mesoporous silica nanoparticle material with 10 nm pore diameter (MSN-10) (medium, 6-12 nm pores), and pore-expanded MSN-10 (large, 15-30 nm pores). Of these six TrzN:MSN biomaterials, it was shown that TrzN:MSN-10 was the most active (3.8 ± 0.4 × 10-5 U/mg) toward the hydrolysis of a 50 μM atrazine solution at 25 °C. The TrzN:MSN-10 biomaterial was then coated in chitosan (TrzN:MSN-10:Chit) as chitosan has been shown to increase stability in extreme conditions such as low/high pH, heat shock, and the presence of organic solvents. TrzN:MSN-10:Chit was shown to be a superior TrzN biomaterial to TrzN:MSN-10 as it exhibited higher activity under all storage conditions, in the presence of 20% MeOH, at low and high pH values, and at elevated temperatures up to 80 °C. Finally, the TrzN:MSN-10:Chit biomaterial was shown to be fully active in river water, which establishes it as a functional biomaterial under actual field conditions. A combination of these data indicate that the TrzN:MSN-10:Chit biomaterial exhibited the best overall catalytic profile making it a promising biocatalyst for the bioremediation of atrazine.

Lactoferrin-Anchored Tannylated Mesoporous Silica Nanomaterials-Induced Bone Fusion in a Rat Model of Lumbar Spinal Fusion.

Lactoferrin (LF) is a potent antiviral, anti-inflammatory, and antibacterial agent found in cow and human colostrum which acts as an osteogenic growth factor. This study aimed to investigate whether LF-anchored tannylated mesoporous silica nanomaterials (TA-MSN-LF) function as a bone fusion material in a rat model. In this study, we created TA-MSN-LF and measured the effects of low (1 μg) and high (100 μg) TA-MSN-LF concentrations in a spinal fusion animal model. Rats were assigned to four groups in this study: defect, MSN, TA-MSN-LF-low (1 μg/mL), and TA-MSN-LF-high (100 μg/mL). Eight weeks after surgery, a greater amount of radiological fusion was identified in the TA-MSN-LF groups than in the other groups. Hematoxylin and eosin staining showed that new bone fusion was induced in the TA-MSN-LF groups. Additionally, osteocalcin, a marker of bone formation, was detected by immunohistochemistry, and its intensity was induced in the TA-MSN-LF groups. The formation of new vessels was induced in the TA-MSN-LF-high group. We also confirmed an increase in the serum osteocalcin level and the mRNA expression of osteocalcin and osteopontin in the TA-MSN-LF groups. TA-MSN-LF showed effective bone fusion and angiogenesis in rats. We suggest that TA-MSN-LF is a potent material for spinal bone fusion.

Synthesis of novel metal silica nanoparticles exhibiting antimicrobial potential and applications to combat periodontitis

Periodontitis is a severe form of gum disease caused by bacterial plaque that affects millions of people and has substantial worldwide health and economic implications. However, current clinical antiseptic and antimicrobial drug therapies are insufficient because they frequently have numerous side effects and contribute to widespread bacterial resistance. Recently, nanotechnology has shown promise in the synthesis of novel periodontal therapeutic materials. Nanoparticles are quickly replacing antibiotics in the treatment of bacterial infections, and their potential application in dentistry is immense. The alarming increases in antimicrobial resistance further emphasize the importance of exploring and utilizing nanotechnology in the fight against tooth diseases particularly periodontitis. We developed 16 different combinations of mesoporous silica nanomaterials in this study by ageing, drying, and calcining them with 11 different metals including silver, zinc, copper, gold, palladium, ruthenium, platinum, nickel, cerium, aluminium, and zirconium. The antibacterial properties of metal-doped silica were evaluated using four distinct susceptibility tests. The agar well diffusion antibacterial activity test, which measured the susceptibility of the microbes being tested, as well as the antibacterial efficacy of mesoporous silica with different silica/metal ratios, were among these studies. The growth kinetics experiment was used to investigate the efficacy of various metal-doped silica nanoparticles on microbial growth. To detect growth inhibitory effects, the colony-forming unit assay was used. Finally, MIC and MBC tests were performed to observe the inhibition of microbial biofilm formation. Our findings show that silver- and zinc-doped silica nanoparticles synthesized using the sol-gel method can be effective antimicrobial agents against periodontitis-causing microbes. This study represents the pioneering work reporting the antimicrobial properties of metal-loaded TUD-1 mesoporous silica, which could be useful in the fight against other infectious diseases too.

Epoxy composite coating with excellent anti-corrosion and self-healing properties based on mesoporous silica nano-containers

Anti-corrosion coating containing smart nano-containers loaded with inhibitors played an increasingly important role in extending the coating lifetime and slowing down metal corrosion. Whereas, the low loading capacity of the inhibitors in the nano-container limits its applications. In this work, mesoporous silica (SiO2) nano-materials with large pore diameter were prepared and designed as the nano-containers loaded by 2-amino-5-mercapto-1,3,4-thiadiazole (AMT) inhibitors. The prepared nano-containers not only achieved acid-responsive release ability but also greatly increased the loading capacity of the inhibitors. The results showed that the loading capacity of the AMT inhibitors reached 36% and the release amount of them from the SiO2-based nano-containers increased as the gradually decreased pH value of the system. When the pH was 3, 5 and 7, the release amount of the AMT inhibitors was 92.3%, 73.6% and 50.2%, respectively, indicating that the strong acidic system could exacerbate the metal damage, whereas the increasing release amount of the inhibitors could effectively slow down the metal corrosion. The experiments about the release process of the inhibitors from the nano-container ensured that the epoxy composite coating doped by the above-mentioned nano-containers could exhibit self-healing function under different acidic conditions. In addition, the prepared epoxy composite coating (EP/AMT@MSN-PAA) showed an increasing Rct value with the immersion time (that varied from 3105 Ω·cm2 to 4509 Ω·cm2 when the immersion time lasted from 0 h to 48 h). Compared to the blank epoxy coating (EP), the Rct value significantly decreased from 2876 Ω·cm2 to 658 Ω·cm2 with the time, which indicated that the epoxy composite coating had wonderful anti-corrosion performance and excellent self-healing function in harsh environments.

Strategies for enhanced bioavailability of oxime reactivators in the central nervous system.

Oxime reactivators of acetylcholinesterase are commonly used to treat highly toxic organophosphate poisoning. They are effective nucleophiles that can restore the catalytic activity of acetylcholinesterase; however, their main limitation is the difficulty in crossing the blood-brain barrier (BBB) because of their strongly hydrophilic nature. Various approaches to overcome this limitation and enhance the bioavailability of oxime reactivators in the CNS have been evaluated; these include structural modifications, conjugation with molecules that have transporters in the BBB, bypassing the BBB through intranasal delivery, and inhibition of BBB efflux transporters. A promising approach is the use of nanoparticles (NPs) as the delivery systems. Studies using mesoporous silica nanomaterials, poly (L-lysine)-graft-poly(ethylene oxide) NPs, metallic organic frameworks, poly(lactic-co-glycolic acid) NPs, human serum albumin NPs, liposomes, solid lipid NPs, and cucurbiturils, have shown promising results. Some NPs are considered as nanoreactors for organophosphate detoxification; these combine bioscavengers with encapsulated oximes. This study provides an overview and critical discussion of the strategies used to enhance the bioavailability of oxime reactivators in the central nervous system.

Fabrication of Magnetic Silica Nanomaterials and Their Effects on Algal Harvesting

Harmful algal blooms are a global problem in water environments, and their explosive growth endangers the health of aquatic ecosystems. Magnetic nanomaterials for the harvesting of microalgae have received a lot of attention because of their high efficiency, low cost, and ease of operation. In this study, magnetic mesoporous silica nanomaterials were prepared using Fe3O4 as a carrier and harvesting on Chlorella sp. HQ. It was found that silica coated with magnetic Fe3O4 microspheres has good dispersion. The harvesting of Chlorella sp. HQ via magnetic mesoporous silica could be maintained over a wide pH range (4 to 12). After the removal of organic components from the surface of the material, the magnetic mesoporous silica obtained a better porous structure. The ethanol reflux method was more beneficial than the calcination method in maintaining the stable structure of the material, thus improving the harvesting efficiency of the material for the microalgae Chlorella sp. HQ by a maximum of 17.8% (65.9% to 83.7%). When the molar ratio of active agent cetyltrimethylammonium bromide (CTAB) and stabilizer polyvinylpyrrolidone (PVP) was 1: 0.092 at pH 4 and algal concentration of 0.5 g/L, the materials showed the maximum harvesting efficiency of Chlorella sp. HQ was 84.2%.

Delivery of chiral D-cysteine by pH-responsive mesoporous silica nanoparticles for effective bacterial inhibition

Efficient and highly controllable antibacterial effects, as well as good biocompatibility, are required for antibacterial materials to overcome multi-drug resistance in bacteria. Herein, mesoporous silica nanomaterials (MSNs) carriers with a particle mean size of 60 nm and pore size of 7.9 nm were prepared, which was followed by loading with D-cysteine (D-Cys) and modified with Polyethyleneimine (PEI) molecules on the outer surface (named as D@MSNs-P). The prepared D@MSNs-P showed a good pH response in the range of 5–7, and the rate of antibacterial agent D-Cys released from nanocarriers was much faster at lower pH (pH 5) than that at higher pH (pH 6–7), which favors the rapid control of the pathogenic bacteria. In a working pH (pH 5), D@MSNs-P exhibited broad-spectrum antibacterial activities against Escherichia coli, Staphylococcus aureus, Salmonella enteritidis, and Listeria monocytogenes with the highest antibacterial efficiency of 99.9%, 99.8%, 98.1%, and 96.2%, respectively, which is much higher than that of pure D-Cys, pure MSNs, D@MSNs, and PEI group. The outstanding antibacterial activity of D@MSNs-P was attributed to the synergistic effect of the unique structure of MSNs and chiral D-Cys molecules. In addition, the prepared D@MSNs-P has no cytotoxicity to HepG2 cells (Human hepatoma cells) at the concentration of 0.4–12.8 mg/mL and even can promote cell proliferation at high concentrations. Our results open a new door for designing the most promising nanomaterials for pH response release and controllable antimicrobial.

Folic acid functionalised mesoporous core-shell silica nanoparticles loaded with carboplatin for lung cancer therapy

The development of versatile mesoporous silica nanomaterials (MSNSs) with suitable textural properties is essential for the targeted and precise delivery of therapeutic drugs for the treatment of various diseases. Especially, loading of highly toxic platinum-based drugs is essential to reduce their toxic side effects. However, loading platinum-based drugs such as carboplatin in high quantity in porous materials is extremely challenging owing to the high hydrophobicity and lack of functional groups for interacting with surfaces of MSNS. In this study, we report a facile synthesis of core-shell MSNS by employing a unique combination of triple surfactants - pluronic P123, cetyltrimethylammonium bromide (CTAB) and fluorocarbon-4 (FC-4) for targeted delivery of the carboplatin for the treatment of lung cancer. The highly hydrophobic FC-4 plays a vital role in tuning the self-assembly and thereby controls the size, morphology, textural properties and uniform pore size distribution of the MSNS. The optimised MSNS with the size range of 300–320 nm, uniform size distribution, high surface area and ordered structure was successfully synthesised. A high drug loading of 26.7% was achieved on both bare and amine functionalised MSNS with a steady release of up to 60% and 37%, respectively, in PBS. The targeting efficiency of the folic acid functionalised particles was established by confocal microscopy, which showed higher cellular uptake of these particles in A549 cells. The high carboplatin loading and targeting ability resulted in high cytotoxicity from the folic acid functionalised and drug-loaded MSNS samples in PC9 cells compared to non-targeted and bare MSNS samples. Overall, this study proposes a new single-step synthesis of core-shell MSNS with high drug loading capacity that can be used to deliver drugs in treating different types of cancers.

Multifunctional immunosensors based on mesoporous silica nanomaterials as efficient sensing platforms in biomedical and food safety analysis: A review of current status and emerging applications

Over the last few years, the progress of biosensing has revolutionized the dynamic domain of medical and food safety analysis. Among various factors, the role of materials and nanomaterials in terms of development biosensors is undeniable. Mesoporous silica nanomaterials as an inseparable and vital part of novel analytical approaches can improve their properties. Elaborately, the unique physiochemical properties including great surface area, tunable nanometer-scale pore sizes and ease of substrate modification can make these materials excellent candidates for biosensing. In addition, adding antibodies to the structure of biosensors based on mesoporous silica nanomaterials can boon the selectivity and sensitivity of these biosensing platforms. To illustrate, the specificity and sensitivity of the antigen-antibody interaction improved the feature of these types of biosensors for selective quantification of numerous targets including viruses, biomarkers, bacterial infections cells and bacteria. In this study, we attempted to review the latest advancement of immunoassays based on mesoporous silica nanomaterials which operate according to electrochemical, optical and electrochemiluminescence techniques in the field of food safety and biomedical analysis. In addition, this study can open new windows for exploiting competent sensing methods as laboratory tools by addressing the current challenges and future perspectives. To elaborate, these sensing approaches should evolve for point-of-care analysis and be designed outside of controlled environments using real-life samples with minimal user involvement.

Utilizing Imine Bonds to Create a Self-Gated Mesoporous Silica Material with Controlled Release and Antimicrobial Properties.

In recent years, silica nanomaterials have been widely studied as carriers in the field of antibacterial activity in food. Therefore, it is a promising but challenging proposition to construct responsive antibacterial materials with food safety and controllable release capabilities using silica nanomaterials. In this paper, a pH-responsive self-gated antibacterial material is reported, which uses mesoporous silica nanomaterials as a carrier and achieves self-gating of the antibacterial agent through pH-sensitive imine bonds. This is the first study in the field of food antibacterial materials to achieve self-gating through the chemical bond of the antibacterial material itself. The prepared antibacterial material can effectively sense changes in pH values caused by the growth of foodborne pathogens and choose whether to release antibacterial substances and at what rate. The development of this antibacterial material does not introduce other components, ensuring food safety. In addition, carrying mesoporous silica nanomaterials can also effectively enhance the inhibitory ability of the active substance.

Chiral Skeletons of Mesoporous Silica Nanospheres to Mitigate Alzheimer's β-Amyloid Aggregation.

Chiral mesoporous silica (mSiO2) nanomaterials have gained significant attention during the past two decades. Most of them show a topologically characteristic helix; however, little attention has been paid to the molecular-scale chirality of mSiO2 frameworks. Herein, we report a chiral amide-gel-directed synthesis strategy for the fabrication of chiral mSiO2 nanospheres with molecular-scale-like chirality in the silicate skeletons. The functionalization of micelles with the chiral amide gels via electrostatic interactions realizes the growth of molecular configuration chiral silica sols. Subsequent modular self-assembly results in the formation of dendritic large mesoporous silica nanospheres with molecular chirality of the silica frameworks. As a result, the resultant chiral mSiO2 nanospheres show abundant large mesopores (∼10.1 nm), high pore volumes (∼1.8 cm3·g-1), high surface areas (∼525 m2·g-1), and evident CD activity. The successful transfer of the chirality from the chiral amide gels to composited micelles and further to asymmetric silica polymeric frameworks based on modular self-assembly leads to the presence of molecular chirality in the final products. The chiral mSiO2 frameworks display a good chiral stability after a high-temperature calcination (even up to 1000 °C). The chiral mSiO2 can impart a notable decline in β-amyloid protein (Aβ42) aggregation formation up to 79%, leading to significant mitigation of Aβ42-induced cytotoxicity on the human neuroblastoma line SH-ST5Y cells in vitro. This finding opens a new avenue to construct the molecular chirality configuration in nanomaterials for optical and biomedical applications.

Repurposing Anthelmintics: Rafoxanide- and Copper-Functionalized SBA-15 Carriers against Methicillin-Resistant Staphylococcus aureus.

The development of materials that can more efficiently administer antimicrobial agents in a controlled manner is urgently needed due to the rise in microbial resistance to traditional antibiotics. While new classes of antibiotics are developed and put into widespread usage, existing, inexpensive compounds can be repurposed to fight bacterial infections. Here, we present the synthesis of amine-functionalized SBA-15 mesoporous silica nanomaterials with physisorbed rafoxanide (RFX), a commonly used salicylanilide anthelmintic, and anchored Cu(II) ions that exhibit enhanced antimicrobial efficacy against the pathogenic bacterium Staphylococcus aureus. The synthesized nanomaterials are structurally characterized by a combination of physicochemical, thermal, and optical methods. Additionally, release studies are carried out in vitro to determine the effects of pH and the synthetic sequence used to produce the materials on Cu(II) ion release. Our results indicate that SBA-15 mesoporous silica nanocarriers loaded with Cu(II) and RFX exhibit 10 times as much bactericidal action against wild-type S. aureus as the nanocarrier loaded with only RFX. Furthermore, the synthetic sequence used to produce the nanomaterials could significantly affect (enhance) their bactericidal efficacy.