Recent Trends in Morphology-Controlled Synthesis and Application of Mesoporous Silica Nanoparticles

Resource utilization of waste solar photovoltaic panels for preparation of microporous silicon nanoparticles

With the exponential growth of global photovoltaic (PV) installed capacity, the quantity of discarded PV modules continues to rise. This study innovatively explored the sustainable recovery and utilization of raw materials from discarded solar panels, focusing on the transformation of recycled silicon into microporous silica nanoparticles (MSN). Low toxic organic solvent ethyl acetate (EA) was for the first time utilized to reduce the viscosity of ethylene-vinyl acetate (EVA) and facilitated its removal. A simple combination of nitric acid (HNO3) and sodium hydroxide (NaOH) at low temperatures (225 min HNO3 etching at room temperature followed by 40 min NaOH etching at 70 °C) completely removed the deep blue anti-reflective coating SiNx and successfully removed metallic impurities such as silver (Ag), aluminum (Al). Removal efficiencies for Ag and Al electrodes both reached 99 %, with recovery rates of 92 % and 99 % for Ag and Al, respectively. The recycled Ag and Si had a purity of 99 % and 93.2 %, respectively. The recycled pure Si was then dissolved in a NaOH solution to prepare a sodium silicate (Na2SiO3) solution. Under acidic conditions, the non-ionic surfactant Triton X-100 and cationic surfactant cetyltrimethylammonium bromide (CTAB) were used to transform the Na2SiO3 solution to the MSN. The specific surface area of the MSN measured by BET was 855.30 m2/g, with a pore size of 1.85 nm and a pore volume of 0.3963 cm3/g. This study highlights the innovative utilization of recovered silicon to fabricate advanced microporous materials, paving the way for high-value applications and promoting a sustainable photovoltaic industry.

Plant‐Derived Phytochemicals and Their Nanoformulations for Inducing Programed Cell Death in Cancer

Phytochemicals are a diverse class of compounds found in various plant‐based foods and beverages that have displayed the capacity to exert powerful anticancer effects through the induction of programed cell death (PCD) in malignancies. PCD is a sophisticated process that maintains in upholding tissue homeostasis and eliminating injured or neoplastic cells. Phytochemicals have shown the potential to induce PCD in malignant cells through various mechanisms, including modulation of cell signaling pathways, regulation of reactive oxygen species (ROS), and interaction with critical targets in cells such as DNA. Moreover, recent studies have suggested that nanomaterials loaded with phytochemicals may enhance cell death in tumors, which can also stimulate antitumor immunity. In this review, a comprehensive overview of the current understanding of the anticancer effects of phytochemicals and their potential as a promising approach to cancer therapy, is provided. The impacts of phytochemicals such as resveratrol, curcumin, apigenin, quercetin, and some approved plant‐derived drugs, such as taxanes on the regulation of some types of PCD, including apoptosis, pyroptosis, anoikis, autophagic cell death, ferroptosis, and necroptosis, are discussed. The underlying mechanisms and the potential of nanomaterials loaded with phytochemicals to enhance PCD in tumors are also explained.

Advances in hybridized nanoarchitectures for improved oro-dental health

On a global note, oral health plays a critical role in improving the overall human health. In this vein, dental-related issues with dentin exposure often facilitate the risk of developing various oral-related diseases in gums and teeth. Several oral-based ailments include gums-associated (gingivitis or periodontitis), tooth-based (dental caries, root infection, enamel erosion, and edentulous or total tooth loss), as well as miscellaneous diseases in the buccal or oral cavity (bad breath, mouth sores, and oral cancer). Although established conventional treatment modalities have been available to improve oral health, these therapeutic options suffer from several limitations, such as fail to eradicate bacterial biofilms, deprived regeneration of dental pulp cells, and poor remineralization of teeth, resulting in dental emergencies. To this end, the advent of nanotechnology has resulted in the development of various innovative nanoarchitectured composites from diverse sources. This review presents a comprehensive overview of different nanoarchitectured composites for improving overall oral health. Initially, we emphasize various oral-related diseases, providing detailed pathological circumstances and their effects on human health along with deficiencies of the conventional therapeutic modalities. Further, the importance of various nanostructured components is emphasized, highlighting their predominant actions in solving crucial dental issues, such as anti-bacterial, remineralization, and tissue regeneration abilities. In addition to an emphasis on the synthesis of different nanostructures, various nano-therapeutic solutions from diverse sources are discussed, including natural (plant, animal, and marine)-based components and other synthetic (organic- and inorganic-) architectures, as well as their composites for improving oral health. Finally, we summarize the article with an interesting outlook on overcoming the challenges of translating these innovative platforms to clinics.

Modification of Silica with Sucrose and Ammonium Fluoride Agents: A Facile Route to Prepare Supports of Iridium Catalysts for Hydrogenation Reaction

Mesoporous silica materials were synthesized using inexpensive and environmentally friendly sucrose as a porogeneous agent. It was found that the presence of sucrose and the products of its chemical transformation during synthesis (e.g., furfural polymer) significantly affected the structure of the obtained porous silica. The influence of synthesis conditions (pH, temperature, time) on the textural properties of the final materials was determined. Samples obtained in an acidic medium, at pH = 1, and treated at room temperature, yielded products with a large surface area and a narrow pore size distribution in the range of 2-5 nm, while the synthesis at pH = 8 allowed for the formation of mesoporous systems with pores in the range of 14-20 nm. To generate acidity, the silicas were modified with an ammonium fluoride solution and then used as supports for iridium catalysts in a hydrogenation reaction, with toluene as a model hydrocarbon. The influence of parameters such as specific surface area, support acidity, and iridium dispersion on catalytic activity was determined. It was shown that modification with sucrose improved the porous structure, and NH4F modification generated acidity. These parameters favored better reducibility and dispersion of the active phase, resulting in higher activity of the catalysts in the studied hydrogenation reaction.

Ultrasonic Preparation of Nano-CaCO3 Templates and Hollow Mesoporous SiO2 Nanoparticles for Voriconazole Loading

CaCO3 nanoparticles (nano-CaCO3) as nano-templates were prepared using CaCl2 and Na2CO3 solutions under controlled sonication (19.5 kHz). Using the same ultrasonic device, subsequently, hollow mesoporous silica nanoparticles (HMSNs) were obtained by the hard template of nano-CaCO3. HMSNs were selected as carriers for the antifungal drug voriconazole (VOR) loading to overcome poor water solubility. Three-dimensional CaCO3 nanosheets HMSNs were obtained under gentle sonication. Three-dimensional CaCO3 nanosheets of 24.5 nm (hydrodynamic diameter) were obtained under 17.6 W for 3 min. HMSNs were synthesized by double-template method with nano-CaCO3 as the hard template. Transmission electron microscopy measurements showed that the prepared HMSNs possess hollow structures with particle size between 110 and 120 nm. Nitrogen physisorption at -196 °C revealed that the HMSNs had high surface area (401.57 m2/g), high pore volume (0.11 cm3/g), and uniform pore size (2.22 nm) that facilitated the effective encapsulation of VOR in the HMSNs. The loading capacity of VOR (wt%) on the HMSNs was 7.96%, and the total VOR release amount of VOR-HMSNs material was 71.40% at 480 min. The kinetic model confirmed that the release mechanism of HMSNs nanoparticles followed Fickian diffusion at pH = 7.4 and 37 °C. Moreover, the cumulative VOR release at 42 °C (86.05%) was higher than that at 37 °C (71.40%). The cumulative release amount of VOR from the VOR-HMSNs material was 92.37% at pH = 5.8 at the same temperature. Both nano-CaCO3 templates and HMSNs were prepared by sonication at 19.5 kHz. The as-prepared HMSNs can effectively encapsulate VOR and released drug by Fickian diffusion.

Synthesis of Mesoporous Silica Sol with Low Refractive Properties for Increasing Transmittance

Currently, coating with anti-reflective materials is an attractive approach to improve the quality of screen-based displays. In this study, mesoporous silica particles were systematically synthesized as a function of surfactant (i.e., CTAC-cetyltrimethylammonium chloride) concentration to serve as main coating fillers possessing low refractive indices. Precisely changing the amount of the CTAC surfactant, silica sol with an average diameter of 50 nm exhibits distinctively different specific surface areas, pore size, and pore volume. Prior to the preparation of final coating solutions containing these silica particle fillers, the percentage of solid content was optimized on a glass slide. The use of 50 wt% solid content exhibited the highest transmittance of light. Among various content levels of silica sol, the use of 3.5 wt% of silica particles in the solid content displayed the highest transmittance (i.e., best anti-reflectiveness). Under the almost identical coating layers prepared with the fixed amount of silica particles possessing different surface areas, pore size, and pore volume, it appears that the largest pore volume played the most important role in improving the anti-reflective properties. Experimentally understanding the key feature of low-refractive filler materials under the optimized conditions could provide a clear view to develop highly effective anti-reflective materials for various display applications.

Kinetic detection of hydrogen peroxide in single horseradish peroxidase-concentrated silica particle using confocal fluorescence microspectroscopic measurement

In the present study, we propose a scheme for detecting H2O2 by using horseradish peroxidase (HRP) adsorbed onto single silica particles and fluorescence microspectroscopy. When the silica particles were immersed in an HRP solution, the HRP concentration in the silica particles increased by a factor of 690 compared to that in the bulk aqueous solution because HRP was adsorbed on the silica surface. When a single particle containing HRP was added to a mixed solution of H2O2 and Amplex Red, fluorescence from resorufin, which was produced by the reaction of HRP, H2O2, and Amplex Red, was observed. The fluorescence from the resorufin in the particles increased after a single particle was added to the solution, and the release of resorufin was observed. As the concentration of H2O2 (CH2O2) decreased, the time it takes for fluorescence intensity to reach its maximum was shorter. The detection limit for H2O2 in the present system was 980 nM. The reaction behavior of a single silica particle was evaluated using a spherical diffusion model, which explains the approximate concentration change of resorufin in the silica particle. The proposed method has the advantages of simple sample preparation and detection, low sample consumption, and a short detection time.

Filled Elastomers: Mechanistic and Physics-Driven Modeling and Applications as Smart Materials

Elastomers are made of chain-like molecules to form networks that can sustain large deformation. Rubbers are thermosetting elastomers that are obtained from irreversible curing reactions. Curing reactions create permanent bonds between the molecular chains. On the other hand, thermoplastic elastomers do not need curing reactions. Incorporation of appropriated filler particles, as has been practiced for decades, can significantly enhance mechanical properties of elastomers. However, there are fundamental questions about polymer matrix composites (PMCs) that still elude complete understanding. This is because the macroscopic properties of PMCs depend not only on the overall volume fraction (ϕ) of the filler particles, but also on their spatial distribution (i.e., primary, secondary, and tertiary structure). This work aims at reviewing how the mechanical properties of PMCs are related to the microstructure of filler particles and to the interaction between filler particles and polymer matrices. Overall, soft rubbery matrices dictate the elasticity/hyperelasticity of the PMCs while the reinforcement involves polymer-particle interactions that can significantly influence the mechanical properties of the polymer matrix interface. For ϕ values higher than a threshold, percolation of the filler particles can lead to significant reinforcement. While viscoelastic behavior may be attributed to the soft rubbery component, inelastic behaviors like the Mullins and Payne effects are highly correlated to the microstructures of the polymer matrix and the filler particles, as well as that of the polymer-particle interface. Additionally, the incorporation of specific filler particles within intelligently designed polymer systems has been shown to yield a variety of functional and responsive materials, commonly termed smart materials. We review three types of smart PMCs, i.e., magnetoelastic (M-), shape-memory (SM-), and self-healing (SH-) PMCs, and discuss the constitutive models for these smart materials.

Silica nanoparticles in medicine: overcoming pathologies through advanced drug delivery, diagnostics, and therapeutic strategies

Over the last decades, silica nanoparticles (SiNPs) have been studied for their applications in biomedicine as an alternative used for conventional diagnostics and treatments. Since their properties can be modified and adjusted for the desired use, they have many different potential applications in medicine: they can be used in diagnosis because of their ability to be loaded with dyes and their increased selectivity and sensitivity, which can improve the quality of the diagnostic process. SiNPs can be functionalized by targeting ligands or molecules to detect certain cellular processes or biomarkers with better precision. Targeted delivery is another fundamental use of SiNPs. They could be used as drug delivery systems (DDS) since their structure allows the loading of therapeutic agents or other compounds, and studies have demonstrated their biocompatibility. When SiNPs are used as DDS, the drug's toxicity and the off-target effects are reduced significantly, and they can be used to treat conditions like cancer and neurological diseases and even aid in regenerative processes, such as wound healing or bone repair. However, safety concerns must be considered before SiNPs can be used extensively in clinical practice because NPs can cause toxicity in certain conditions and accumulate at undesired locations. Therefore, an overview of the potential applications that SiNPs could have in medicine, as well as their safety concerns, will be covered in this review paper.

Multifunctional Nanoparticles with Superparamagnetic Mn(II) Ferrite and Luminescent Gold Nanoclusters for Multimodal Imaging

Gold nanoclusters (AuNCs) with fluorescence in the Near Infrared (NIR) by both one- and two-photon electronic excitation were incorporated in mesoporous silica nanoparticles (MSNs) using a novel one-pot synthesis procedure where the condensation polymerization of alkoxysilane monomers in the presence of the AuNCs and a surfactant produced hybrid MSNs of 49 nm diameter. This method was further developed to prepare 30 nm diameter nanocomposite particles with simultaneous NIR fluorescence and superparamagnetic properties, with a core composed of superparamagnetic manganese (II) ferrite nanoparticles (MnFe2O4) coated with a thin silica layer, and a shell of mesoporous silica decorated with AuNCs. The nanocomposite particles feature NIR-photoluminescence with 0.6% quantum yield and large Stokes shift (290 nm), and superparamagnetic response at 300 K, with a saturation magnetization of 13.4 emu g-1. The conjugation of NIR photoluminescence and superparamagnetic properties in the biocompatible nanocomposite has high potential for application in multimodal bioimaging.

Synthesis and characterization of CeO2 and SiO2 nanoparticles and their effect on growth parameters and the antioxidant defense system in Vigna mungo L. Hepper

Engineered nanoparticles (NPs) have recently attracted a lot of attention after being tested in various agricultural plants. This paper reports the green synthesis of CeO2 NPs and SiO2 NPs from leaf extracts of Nyctanthes arbor-tristis. The physical characteristics of the produced nanoparticles were then determined using UV-visible spectroscopy, transmission electron microscopy (TEM), fluorescence spectroscopy, and Fourier transform infrared spectroscopy (FTIR). Furthermore, the interaction effects of cerium oxide NPs (C1, C2, and C3) and silicon dioxide NPs (S1, S2, and S3) at 10 mg/L on blackgram (Vigna mungo L.) were evaluated. CeO2 and SiO2 NPs treatments enhanced the growth performance of the plants by causing a decrease in superoxide radical (SOR) and H2O2 via improving antioxidant enzymes. These findings imply that the size and shape of CeO2 and SiO2 NPs provide defense against oxidative damage to the blackgram.

Recent Advances on Porous Siliceous Materials Derived from Waste

In recent years, significant efforts have been made in view of a transition from a linear to a circular economy, where the value of products, materials, resources, and waste is maintained as long as possible in the economy. The re-utilization of industrial and agricultural waste into value-added products, such as nanostructured siliceous materials, has become a challenging topic as an effective strategy in waste management and a sustainable model aimed to limit the use of landfill, conserve natural resources, and reduce the use of harmful substances. In light of these considerations, nanoporous silica has attracted attention in various applications owing to the tunable pore dimensions, high specific surface areas, tailorable structure, and facile post-functionalization. In this review, recent progress on the synthesis of siliceous materials from different types of waste is presented, analyzing the factors influencing the size and morphology of the final product, alongside different synthetic methods used to impart specific porosity. Applications in the fields of wastewater/gas treatment and catalysis are discussed, focusing on process feasibility in large-scale productions.

Recent Developments on the Catalytic and Biosensing Applications of Porous Nanomaterials

Nanoscopic materials have demonstrated a versatile role in almost every emerging field of research. Nanomaterials have come to be one of the most important fields of advanced research today due to its controllable particle size in the nanoscale range, capacity to adopt diverse forms and morphologies, high surface area, and involvement of transition and non-transition metals. With the introduction of porosity, nanomaterials have become a more promising candidate than their bulk counterparts in catalysis, biomedicine, drug delivery, and other areas. This review intends to compile a self-contained set of papers related to new synthesis methods and versatile applications of porous nanomaterials that can give a realistic picture of current state-of-the-art research, especially for catalysis and sensor area. Especially, we cover various surface functionalization strategies by improving accessibility and mass transfer limitation of catalytic applications for wide variety of materials, including organic and inorganic materials (metals/metal oxides) with covalent porous organic (COFs) and inorganic (silica/carbon) frameworks, constituting solid backgrounds on porous materials.

Hantzsch reaction using copper nitrate hydroxide-containing mesoporous silica nanoparticle with C3N4 framework as a novel powerful and reusable catalyst

Copper nitrate hydroxide (CNH)-containing mesoporous silica nanoparticle (MSN) with g-C₃N₄ framework (MSN/C₃N₄/CNH) was fabricated via a four-step hydrothermal synthesis method. Functionalized MSN-based C₃N₄ was prepared, decorated with CNH, and identified by different physicochemical techniques such as FT-IR, XRD, SEM, EDX, and STA analyses. Then, MSN/C₃N₄/CNH composite was utilized as a robust catalyst for the fast fabrication of biologically active polyhydroquinoline derivatives with high yields between 88 and 97% via Hantzsch reaction under mild reaction conditions and short reaction time (within 15 min) owing to synergistic influence of Lewis acid and base sites. Moreover, MSN/C₃N₄/CNH can be straightforwardly recovered and used up to six reaction cycles without a conspicuous decrease in efficiency.

Synthesis of nanostructured silica particles for controlled release of ascorbic acid: Microstructure features and In Vitro scratch wound assay

To date, the long term stability of ascorbic acid (AA) under physiological conditions represents a major issue for wound healing and tissue regeneration applications. In this study, ascorbyl phosphate (AP) was loaded into silica nanoparticles (SiNPs) through a simple one-step procedure, in which spherical shaped porous SiNPs were obtained via hydrolysis/condensation of tetraethylorthosilicate (TEOS) in the presence of bicarbonate salt and ammonia. The as-prepared SiNPs were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and Fourier Transformer Infrared Spectrophotometer (FTIR). Incorporation of bicarbonate salt resulted in the formation of spherical SiNPs with an average diameter of 460 ± 89 nm, while further increase of bicarbonate salt led to the formation of silica sheet-like structures. The AP-loaded SiNPs exhibited high loading efficiency from 92.3- 81.5%, according to AP content and sustained release over 3 days. According to cell viability assay, the obtained AP-enriched SiNPS showed no toxicity and supportive effect to the proliferation of human skin fibroblast cells (HSF) at a concentration less than 200 μg/mL. Moreover, it was observed that the wound closure percentage (%) after 24 h was also shown to increase to 74.1 ± 3.1% for 20AP-loaded SiNPs compared to control samples (50.1 ± 1.8%). The obtained results clearly demonstrated that the developed SiNPs formulation exhibits optimal microstructure features to maintain a sustained release of AA at wound bed for the healing of skin tissue, including acute and chronic wounds. This article is protected by copyright. All rights reserved.

Green preparation and characterization of AGC-ZM-2022 as a novel mesoporous silica material using palmitic acid as a natural template

In this research project, the preparation of a novel mesoporous silica compound (AGC-ZM-2022) using a fatty acid as a template has been reported for the first time. This mesoporous silica compound was designed using palmitic acid as a template, which is one of the most common saturated fatty acids found in animals, plants, and microorganisms. AGC-ZM-2022 mesoporous silica was prepared using tetraethylorthosilicate as a silica source and palmitic acid as a template (instead of traditional templates) through the sol-gel method. The physical properties and structure of AGC-ZM-2022 were studied by FT-IR, SEM, XRD, TEM, and BET techniques.

Nanosphere Structures Using Various Materials: A Strategy for Signal Amplification for Virus Sensing

Nanomaterials have been explored in the sensing research field in the last decades. Mainly, 3D nanomaterials have played a vital role in advancing biomedical applications, and less attention was given to their application in the field of biosensors for pathogenic virus detection. The versatility and tunability of a wide range of nanomaterials contributed to the development of a rapid, portable biosensor platform. In this review, we discuss 3D nanospheres, one of the classes of nanostructured materials with a homogeneous and dense matrix wherein a guest substance is carried within the matrix or on its surface. This review is segmented based on the type of nanosphere and their elaborative application in various sensing techniques. We emphasize the concept of signal amplification strategies using different nanosphere structures constructed from a polymer, carbon, silica, and metal-organic framework (MOF) for rendering high-level sensitivity of virus detection. We also briefly elaborate on some challenges related to the further development of nanosphere-based biosensors, including the toxicity issue of the used nanomaterial and the commercialization hurdle.

Long-Term Refrigerated Storage of Beef Using an Active Edible Film Reinforced with Mesoporous Silica Nanoparticles Containing Oregano Essential Oil (Lippia graveolens Kunth)

Beef is a fundamental part of the human diet, but it is highly susceptible to microbiological and physicochemical deterioration which decrease its shelf life. This work aimed to formulate an active edible film (AEF) incorporated with amino-functionalized mesoporous silica nanoparticles (A-MSN) loaded with Mexican oregano (Lippia graveolens Kunth) essential oil (OEO) and to evaluate its effect as a coating on fresh beef quality during refrigerated storage. The AEF was based on amaranth protein isolate (API) and chitosan (CH) (4:1, w/w), to which OEO emulsified or encapsulated in A-MSN was added. The tensile strength (36.91 ± 1.37 MPa), Young's modulus (1354.80 ± 64.6 MPa), and elongation (4.71%) parameters of AEF made it comparable with synthetic films. The antimicrobial activity of AEF against E. coli O157:H7 was improved by adding 9% (w/w) encapsulated OEO, and interactions of glycerol and A-MSN with the polymeric matrix were observed by FT-IR spectroscopy. In fresh beef, after 42 days, AEF reduced the population growth (Log CFU/cm², relative to uncoated fresh beef) of Brochothrix thermosphacta (5.5), Escherichia coli (3.5), Pseudomonas spp. (2.8), and aerobic mesophilic bacteria (6.8). After 21 days, odor acceptability of coated fresh beef was improved, thus, enlarging the shelf life of the beef and demonstrating the preservation capacity of this film.

Visible-Light-Driven CO2 Reduction into Methanol Utilizing Sol-Gel-Prepared CeO2-Coupled Bi2O3 Nanocomposite Heterojunctions

Carbon dioxide (CO2) photoreduction into renewable fuels over semiconductor photocatalysts has emerged as a green and sustainable alternative for energy production. Consequently, tremendous efforts are being performed to develop robust and sustainable photocatalysts. Therefore, visible-light active nanocomposite photocatalysts composed of 5.0–20.0 wt.% bismuth oxide (Bi2O3) and cerium oxide (CeO2) were synthesized by a sol-gel-based process. The prepared nanocomposites were evaluated for the promoted photocatalytic reduction of CO2 into methanol (CH3OH). Various characterizations of the obtained photocatalysts exposed an outstanding development of crystalline structure, morphology, and surface texture due to the presence of Bi2O3. Moreover, the absorbance of light in the visible regime was improved with enhanced charge separation, as revealed by the exploration of optical response, photoluminescence, and photocurrent measurements. The overall bandgap calculations revealed a reduction to 2.75 eV for 15% Bi2O3/CeO2 compared to 2.93 eV for pure CeO2. Moreover, the adjusted 2.8 g L−1 dose of 15% Bi2O3/CeO2 selectively produced 1300 μmol g−1 CH3OH after 9 h of visible light irradiation. This photocatalyst also exhibits bearable reusability five times. The improved progression of 15% Bi2O3/CeO2 is denoted by significant charge separation as well as enhanced mobility. This study suggests the application of metal oxide-based heterojunctions for renewable fuel production under visible light.

New Mesoporous Silica Materials Loaded with Polyphenols: Caffeic Acid, Ferulic Acid and p-Coumaric Acid as Dietary Supplements for Oral Administration

In this study, two types of mesoporous silica with different pore structures and volumes were synthesized by the soft-templating method. The two types of mesoporous silica, type MCM-41 and MCM-48, were loaded with three polyphenols-caffeic acid, p-coumaric acid and trans-ferulic acid-in the same ratio of mesoporous silica:polyphenol (1:0.4 w/w). The materials obtained were characterized from a morphological and structural point of view through different analysis techniques. Through X-ray diffraction (XRD), the crystallization plane and the ordered structure of the mesoporous silica were observed. The difference between the two types of materials containing MCM-41 and MCM-48 was observed through the different morphologies of the silica particles through scanning electron microscopy (SEM) and also through the Brunauer-Emmet-Teller (BET) analysis, that the surface areas and volumes of pores was different between the two types of mesoporous silica, and, after loading with polyphenols, the values were reduced. The characteristic bands of silica and of polyphenols were easily observed by Fourier-transform infrared spectroscopy (FTIR), and, through thermogravimetric analysis (TGA), the residual mass was determined and the estimated amount of polyphenol in the materials and the efficient loading of mesoporous silica with polyphenols could be determined. The in vitro study was performed in two types of simulated biological fluids with different pH-simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). The obtained materials could be used in various biomedical applications as systems with controlled release of natural polyphenols and the most suitable application could be as food supplements especially when a mixture of such materials is used or when the polyphenols are co-loaded within the mesoporous silica.

Comparative Study between Two Simple Synthesis Methods for Obtaining Green Gold Nanoparticles Decorating Silica Particles with Antibacterial Activity

The SiO₂ particles system is one of the most common ways to protect colloidal metal systems, such as gold nanoparticles, from aggregation and activity loss due to their high chemical stability and low reactivity. In this study, silica green gold nanoparticles (AuNPs synthesized with mullein extract) were fabricated using two different sol-gel methods. The nanoparticles were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Fourier Transformed Infrared (FTIR), and the antibacterial activity against pathogens (Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella enterica). Synthesis-1 nanoparticles had a kidney-shaped form and uniform distribution, while synthesis-2 nanoparticles had a spherical and non-uniform form. Characterization showed that temperature is an important factor in the distribution of AuNPs in silica; a decrease allowed the formation of Janus-type, and an increase showed a higher concentration of gold in energy-dispersive spectroscopy (EDS) analysis. Overall, similar bands of the two synthesis silica nanoparticles were observed in FTIR, while XRD spectra showed differences in the preferential growth in AuNPs depending on the synthesis. Higher antibacterial activity was observed against S. aureus, which was followed by L. monocytogenes. No differences were observed in the antibacterial activity between the two different sol-gel methods.

Recent advances in biobased and biodegradable polymer nanocomposites, nanoparticles, and natural antioxidants for antibacterial and antioxidant food packaging applications

Inorganic nanoparticles (NPs) and natural antioxidant compounds are an emerging trend in the food industry. Incorporating these substances in biobased and biodegradable matrices as polysaccharides (e.g., starch, cellulose, and chitosan) and proteins has highlighted the potential in active food packaging applications due to more significant antimicrobial, antioxidant, UV blocking, oxygen scavenging, water vapor permeability effects, and low environmental impact. In recent years, the migration of metal NPs and metal oxides in food contact packaging and their toxicological potential have raised concerns about the safety of the nanomaterials. In this review, we provide a comprehensive overview of the main biobased and biodegradable polymer nanocomposites, inorganic NPs, natural antioxidants, and their potential use in active food packaging. The intrinsic properties of NPs and natural antioxidant actives in packaging materials are evaluated to extend shelf-life, safety, and food quality. Toxicological and safety aspects of inorganic NPs are highlighted to understand the current controversy on applying some nanomaterials in food packaging. The synergism of inorganic NPs and plant-derived natural antioxidant actives (e.g., vitamins, polyphenols, and carotenoids) and essential oils (EOs) potentiated the antibacterial and antioxidant properties of biodegradable nanocomposite films. Biodegradable packaging films based on green NPs-this is biosynthesized from plant extracts-showed suitable mechanical and barrier properties and had a lower environmental impact and offered efficient food protection. Furthermore, AgNPs and TiO₂ NPs released metal ions from packaging into contents insufficiently to cause harm to human cells, which could be helpful to understanding critical gaps and provide progress in the packaging field.

Peptides to Overcome the Limitations of Current Anticancer and Antimicrobial Nanotherapies

Biomedical research devotes a huge effort to the development of efficient non-viral nanovectors (NV) to improve the effectiveness of standard therapies. NVs should be stable, sustainable and biocompatible and enable controlled and targeted delivery of drugs. With the aim to foster the advancements of such devices, this review reports some recent results applicable to treat two types of pathologies, cancer and microbial infections, aiming to provide guidance in the overall design of personalized nanomedicines and highlight the key role played by peptides in this field. Additionally, future challenges and potential perspectives are illustrated, in the hope of accelerating the translational advances of nanomedicine.

Tunable synthesis of dendritic fibrous nano silica using 1-pentanol-water microemulsion at low oil to water ratio

Dendritic fibrous nanosilica (DFNS) is a suitable nano-carrier for loading pesticides with radially oriented pores and a large surface area. The microemulsion method is standard method to prepare DFNS, and 1-pentanol is taken to replace cyclohexane as an oil solvent due to its high stability and nontoxic property. The results showed that the volume ratio of 1-pentanol (oil) to water (O/W) and the molar ratio of hexadecyltrimethylammonium bromide (CTAB) to tetraethylorthosilicate (TEOS) had effected on morphology and adsorption properties of DFNS in the water-CTAB-1-pentanol-ethanol-trimethylbenzene (TMB) microemulsion system. DFNS with bicontinuous concentric lamellar morphologies can be synthesized in this microemulsion at the meager O/W volume ratio (0.025-0.045). It features a tight mesoporous structure with a thin dendritic fibrous in 0.03 to 0.04 O/W volume ratio. The particle sizes, surface areas, and porosity of DFNS were positively correlated with the addition of the silica precursor TEOS. The size of DFNS increased from 123 to about 220 nm with the CTAB/TEOS molar ratio decreasing from 0.119 to 0.050. When the molar ratio of CTAB to TEOS  = 0.119, DFNS has a smaller particle size (123 nm) with a larger surface area and abundant honeycomb mesopores; the low O/W volume ratio strategy provides theoretical support for the industrialization development of DFNS and nano-pesticides, which plays a profound role in promoting the sustainable development of pesticide reduction, efficiency and green agriculture.

Formulation and Biological Evaluation of Mesoporous Silica Nanoparticles Loaded with Combinations of Sortase A Inhibitors and Antimicrobial Peptides

This study aimed to develop synergistic therapies to treat superbug infections through the encapsulation of sortase A inhibitors (SrtAIs; trans-chalcone (TC), curcumin (CUR), quercetin (QC), or berberine chloride (BR)) into MCM-41 mesoporous silica nanoparticles (MSNs) or a phosphonate-modified analogue (MCM-41-PO₃⁻) to overcome their poor aqueous solubility. A resazurin-modified minimum inhibitory concentration (MIC) and checkerboard assays, to measure SrtAI synergy in combination with leading antimicrobial peptides (AMPs; pexiganan (PEX), indolicidin (INDO), and [I5, R8] mastoparan (MASTO)), were determined against methicillin-sensitive (MSSA) and methicillin-resistant (MRSA) Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The results demonstrated that the MCM-41 and MCM-41-PO₃⁻ formulations significantly improved the aqueous solubility of each SrtAI. The MICs for SrtAI/MCM-41-PO₃⁻ formulations were lower compared to the SrtAI/MCM-41 formulations against tested bacterial strains, except for the cases of BR/MCM-41 and QC/MCM-41 against P. aeruginosa. Furthermore, the following combinations demonstrated synergy: PEX with TC/MCM-41 (against all strains) or TC/MCM-41-PO₃⁻ (against all strains except P. aeruginosa); PEX with BR/MCM-41 or BR/MCM-41-PO₃⁻ (against MSSA and MRSA); INDO with QC/MCM-41 or QC/MCM-41-PO₃⁻ (against MRSA); and MASTO with CUR/MCM-41 (against E. coli). These combinations also reduced each components’ toxicity against human embryonic kidney cells. In conclusion, MCM-41 MSNs provide a platform to enhance SrtAI solubility and demonstrated antimicrobial synergy with AMPs and reduced toxicity, providing novel superbug treatment opportunities.

Inorganic Nanoparticles in Bone Healing Applications

Modern biomedicine aims to develop integrated solutions that use medical, biotechnological, materials science, and engineering concepts to create functional alternatives for the specific, selective, and accurate management of medical conditions. In the particular case of tissue engineering, designing a model that simulates all tissue qualities and fulfills all tissue requirements is a continuous challenge in the field of bone regeneration. The therapeutic protocols used for bone healing applications are limited by the hierarchical nature and extensive vascularization of osseous tissue, especially in large bone lesions. In this regard, nanotechnology paves the way for a new era in bone treatment, repair and regeneration, by enabling the fabrication of complex nanostructures that are similar to those found in the natural bone and which exhibit multifunctional bioactivity. This review aims to lay out the tremendous outcomes of using inorganic nanoparticles in bone healing applications, including bone repair and regeneration, and modern therapeutic strategies for bone-related pathologies.

Multifunctional Mesoporous Silica Nanoparticles for Oral Drug Delivery

Nanotechnology has transformed engineering designs across a wide spectrum of materials and applications. Mesoporous Silica Nanoparticles (MSNs) are one of the new fabrications of nanostructures as medication delivery systems. MSNs have pore sizes varying from 2 to 50 nm, making them ideal for a variety of biological applications. They offer unique characteristics such as a tunable surface area, well-defined surface properties, and the ability to improve drug pharmacokinetic characteristics. Moreover, they have the potential to reduce adverse effects by delivering a precise dose of medications to a specific spot rather than the more frequent systemic delivery, which diffuses across tissues and organs. In addition, the vast number of pores allow drug incorporation and transportation of drugs to various sites making MSNs a feasible platform for orally administered drugs. Though the oral route is the most suitable and convenient platform for drug delivery, conventional oral drug delivery systems are associated with several limitations. Surpassing gastrointestinal barriers and the low oral bioavailability of poorly soluble medicines pose a major challenge in the pharmaceutical industry. This review provides insights into the role of MSNs and its mechanism as an oral drug delivery system.

Mesoporous Silica Nanoparticles in Chemical Detection: From Small Species to Large Bio-Molecules

A recompilation of applications of mesoporous silica nanoparticles in sensing from the last five years is presented. Its high potential, especially as hybrid materials combined with organic or bio-molecules, is shown. Adding to the multiplying effect of loading high amounts of the transducer into the pores, the selectivity attained by the interaction of the analyte with the layer decorating the material is described. Examples of the different methodologies are presented.

Kidney-Protector Lipidic Cilastatin Derivatives as Structure-Directing Agents for the Synthesis of Mesoporous Silica Nanoparticles for Drug Delivery

Mesoporous silica nanomaterials have emerged as promising vehicles in controlled drug delivery systems due to their ability to selectively transport, protect, and release pharmaceuticals in a controlled and sustained manner. One drawback of these drug delivery systems is their preparation procedure that usually requires several steps including the removal of the structure-directing agent (surfactant) and the later loading of the drug into the porous structure. Herein, we describe the preparation of mesoporous silica nanoparticles, as drug delivery systems from structure-directing agents based on the kidney-protector drug cilastatin in a simple, fast, and one-step process. The concept of drug-structure-directing agent (DSDA) allows the use of lipidic derivatives of cilastatin to direct the successful formation of mesoporous silica nanoparticles (MSNs). The inherent pharmacological activity of the surfactant DSDA cilastatin-based template permits that the MSNs can be directly employed as drug delivery nanocarriers, without the need of extra steps. MSNs thus synthesized have shown good sphericity and remarkable textural properties. The size of the nanoparticles can be adjusted by simply selecting the stirring speed, time, and aging temperature during the synthesis procedure. Moreover, the release experiments performed on these materials afforded a slow and sustained drug release over several days, which illustrates the MSNs potential utility as drug delivery system for the cilastatin cargo kidney protector. While most nanotechnology strategies focused on combating the different illnesses this methodology emphasizes on reducing the kidney toxicity associated to cancer chemotherapy.

High Surface Area Mesoporous Silica Nanoparticles with Tunable Size in the Sub-Micrometer Regime: Insights on the Size and Porosity Control Mechanisms

Mesoporous silica nanostructures (MSNs) attract high interest due to their unique and tunable physical chemical features, including high specific surface area and large pore volume, that hold a great potential in a variety of fields, i.e., adsorption, catalysis, and biomedicine. An essential feature for biomedical application of MSNs is limiting MSN size in the sub-micrometer regime to control uptake and cell viability. However, careful size tuning in such a regime remains still challenging. We aim to tackling this issue by developing two synthetic procedures for MSN size modulation, performed in homogenous aqueous/ethanol solution or two-phase aqueous/ethyl acetate system. Both approaches make use of tetraethyl orthosilicate as precursor, in the presence of cetyltrimethylammonium bromide, as structure-directing agent, and NaOH, as base-catalyst. NaOH catalyzed syntheses usually require high temperature (>80 °C) and large reaction medium volume to trigger MSN formation and limit aggregation. Here, a successful modulation of MSNs size from 40 up to 150 nm is demonstrated to be achieved by purposely balancing synthesis conditions, being able, in addition, to keep reaction temperature not higher than 50 °C (30 °C and 50 °C, respectively) and reaction mixture volume low. Through a comprehensive and in-depth systematic morphological and structural investigation, the mechanism and kinetics that sustain the control of MSNs size in such low dimensional regime are defined, highlighting that modulation of size and pores of the structures are mainly mediated by base concentration, reaction time and temperature and ageing, for the homogenous phase approach, and by temperature for the two-phase synthesis. Finally, an in vitro study is performed on bEnd.3 cells to investigate on the cytotoxicity of the MNSs.

Surface Energy of Curved Surface Based on Lennard-Jones Potential

Although various phenomena have confirmed that surface geometry has an impact on surface energy at micro/nano scales, determining the surface energy on micro/nano curved surfaces remains a challenge. In this paper, based on Lennard-Jones (L-J) pair potential, we study the geometrical effect on surface energy with the homogenization hypothesis. The surface energy is expressed as a function of local principle curvatures. The accuracy of curvature-based surface energy is confirmed by comparing surface energy on flat surface with experimental results. Furthermore, the surface energy for spherical geometry is investigated and verified by the numerical experiment with errors within 5%. The results show that (i) the surface energy will decrease on a convex surface and increase on a concave surface with the increasing of scales, and tend to the value on flat surface; (ii) the effect of curvatures will be obvious and exceed 5% when spherical radius becomes smaller than 5 nm; (iii) the surface energy varies with curvatures on sinusoidal surfaces, and the normalized surface energy relates with the ratio of wave height to wavelength. The curvature-based surface energy offers new insights into the geometrical and scales effect at micro/nano scales, which provides a theoretical direction for designing NEMS/MEMS.