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

Characterizing Lipid-Coated Mesoporous Silica Nanoparticles as CD169-Binding Delivery System for Rilpivirine and Cabotegravir

Herein, lipid-coated mesoporous silica nanoparticles (LMSN) are investigated as biomimetic delivery vehicle for two antiretroviral compounds (ARVs), rilpivirine (RPV) and cabotegravir (CAB). Monosialodihexosylganglioside (GM3) is incorporated into the membrane to facilitate LMSN binding to CD169 (Siglec-1)-expressing myeloid cells, that are predominantly expressed in secondary lymphoid tissues in vivo. It is demonstrated that in addition to providing CD169-binding functionalities, the lipid membrane around the silica core provides stealth properties that dampen the inflammatory cytokine response to ARVs-loaded LMSN in human monocyte-derived macrophages. Quantification of RPV and CAB releases from nanoparticles, and assessment of antiviral potency to human immunodeficiency virus (HIV-1) infection in vitro reveals that RPV and CAB co-formulated into LMSN retain optimal antiviral potency for 90 days, even upon storage at room temperature, making LMSN an attractive nanoplatform, immune to cold chain requirements. These findings suggest that GM3-LMSN equip the mesoporous silica nanoparticle (MSN) core with lipid-derived properties for surface passivation and lipid-mediated binding that are of high interest for achieving an effective delivery of ARVs to tissue reservoirs of HIV-1 replication.

Reproductive toxicity investigation of silica nanoparticles in male pubertal mice

Silica nanoparticles (SiNPs), one of the most produced nanoparticles (NPs) in the world, are used in all aspects of life. The increased application of SiNPs, especially in medicine, has raised considerable concern regarding their toxicological impact. Previous studies have shown that SiNPs can pass through the reproductive barrier and cause reproductive organ dysfunction by destroying Sertoli cells, Leydig cells, and germ cells. However, little is known about the mechanism of SiNPs-induced reproductive toxicity. In the present study, 5-week-old male mice were intraperitoneally administered SiNPs per day for 1 week at a dose of 0.2 mg per mouse. The results showed that SiNPs could cause damage to the structure of the testis and the epididymis and change the reproductive organ coefficients, leading to decreases of 56.1% and 55.3% in the rates of sperm concentration and motility and an increase of 168.8% in the rate of sperm abnormality. Moreover, the serum testosterone level obviously decreased from 18.77 to 5.23 µg/ml after exposure, and the transcription statuses of some key genes involved in the synthesis and transport of testosterone in the testis were also affected. Additional experiments showed that SiNPs exposure during puberty induced oxidative stress and an inflammatory response, as shown by the changed activity of superoxide dismutase (SOD), increased contents of malondialdehyde (MDA), and excess expression of proinflammatory factors, including TNF-α and IL-1β. Furthermore, the administration of SiNPs caused DNA damage and cell apoptosis, which were presented by the increased apoptotic cells in the sections of testis and epididymis and activation of the TNF-α/TNFR I-mediated pro-apoptotic pathway. In conclusion, these results indicate that SiNPs exposure during puberty significantly damaged the structure and function of the testis and epididymis by inducing oxidative stress and cell apoptosis. This study provides novel insight into SiNPs-induced reproductive toxicity during puberty, which warrants a more careful assessment of SiNPs before their application in juvenile supplies.

Induction of Cartilage Regeneration by Nanoparticles Loaded with Dentin Matrix Extracted Proteins

Due to the limited self-repair capacity of articular cartilage, tissue engineering has good application prospects for cartilage regeneration. Dentin contains several key growth factors involved in cartilage regeneration. However, it remains unknown whether dentin matrix extracted proteins (DMEP) can be utilized as a complex growth-factor mixture to induce cartilage regeneration. In this work, we extracted DMEP from human dentin and improved the content and activity of chondrogenic-related growth factors in DMEP by alkaline conditioning. Afterwards, mesoporous silica nanoparticles (MSNs) with particular physical and chemical properties were composed to selectively load and sustain the release of proteins in DMEP. MSN-DMEP promoted chondrogenic differentiation of rat bone marrow-derived mesenchymal stem cells with fewer growth factors than exogenously added transforming growth factor-β1 (TGF-β1). Therefore, MSN-DMEP may serve as a promising candidate for cartilage regeneration as an alternative to expensive synthetic growth factors.

Real-Time and In Situ Monitoring of the Synthesis of Silica Nanoparticles

The real-time and in situ monitoring of the synthesis of nanomaterials (NMs) remains a challenging task, which is of pivotal importance by assisting fundamental studies (e.g., synthesis kinetics and colloidal phenomena) and providing optimized quality control. In fact, the lack of reproducibility in the synthesis of NMs is a bottleneck against the translation of nanotechnologies into the market toward daily practice. Here, we address an impedimetric millifluidic sensor with data processing by machine learning (ML) as a sensing platform to monitor silica nanoparticles (SiO₂NPs) over a 24 h synthesis from a single measurement. The SiO₂NPs were selected as a model NM because of their extensive applications. Impressively, simple ML-fitted descriptors were capable of overcoming interferences derived from SiO₂NP adsorption over the signals of polarizable Au interdigitate electrodes to assure the determination of the size and concentration of nanoparticles over synthesis while meeting the trade-off between accuracy and speed/simplicity of computation. The root-mean-square errors were calculated as ∼2.0 nm (size) and 2.6 × 10¹⁰ nanoparticles mL^-1 (concentration). Further, the robustness of the ML size descriptor was successfully challenged in data obtained along independent syntheses using different devices, with the global average accuracy being 103.7 ± 1.9%. Our work advances the developments required to transform a closed flow system basically encompassing the reactional flask and an impedimetric sensor into a scalable and user-friendly platform to assess the in situ synthesis of SiO₂NPs. Since the sensor presents a universal response principle, the method is expected to enable the monitoring of other NMs. Such a platform may help to pave the way for translating "sense-act" systems into practice use in nanotechnology.

Fabrication of Brønsted acidic ionic liquids functionalized organosilica nanospheres for microwave-assisted fructose valorization

A series of Brønsted acidic ionic liquids (BAILs) functionalized hollow organosilica nanospheres ([C_3/4Im][OTs/OTf]-Si(Et)Si, C_3/4 = Pr/BuSO₃H) were synthesized by two steps. The process involved the preparation of hollow nanosphere supports via a toluene-swollen sol-gel co-condensation of 1,2-bis(trimethoxysilyl)ethane and 3-chloropropyltriethoxysilane in the presence of F127, and followed by a successive quaternary ammonization and protonation with imidazole, 1,3-propane/1,4-butane sultone and trifluoromethane sulfonic acid/p-toluenesulfonic acid. The adjustable acid property, hollow inner diameter (5-15 nm) and shell thickness (5-9 nm) of [C_3/4Im][OTs/OTf]-Si(Et)Si are achieved by introducing different organic acids and controlling toluene concentration, respectively. The [C_3/4Im][OTs/OTf]-Si(Et)Si were applied in selective conversion of fructose to 5-hydroxymethylfurfural (HMF) and 5-ethoxymethylfurfural (EMF) under microwave heating. Under the optimized conditions, the [C₄Im][OTs]-Si(Et)Si3.0 nanospheres with the largest inner diameter and the smallest shell thickness exhibit the highest HMF yield (79.4%, 15 min) in fructose dehydration. And the [C₃Im][OTf]-Si(Et)Si0.5 nanospheres with the highest acid strength possess the highest EMF yield (70.4%, 30 min) in fructose ethanolysis. The high Brønsted acid-site density and acid strength of [C_3/4Im][OTs/OTf]-Si(Et)Si catalysts accompanied by high microwave heating energy lead to excellent dehydration/ethanolysis activity. The product selectivity strongly depended on the BAILs structures and morphological characteristics of the catalyst. More importantly, the [C_3/4Im][OTs/OTf]-Si(Et)Si can be reused three times without changes in leaching of BAILs, due to strong covalent bond between BAILs and silicon/carbon framework. This work will provide a simple strategy of chemically bonded BAILs on suitable supports as efficient solid acids, and an approach of combining morphology-controlled solid acids with microwave-heating for catalytic conversion of biomass/derivatives to fuels and value-added chemicals.

Mesoporous Silica-Based Nanoparticles as Non-Viral Gene Delivery Platform for Treating Retinitis Pigmentosa

BACKGROUND

Gene therapy is a therapeutic possibility for retinitis pigmentosa (RP), in which therapeutic transgenes are currently delivered to the retina by adeno-associated viral vectors (AAVs). Although their safety and efficacy have been demonstrated in both clinical and preclinical settings, AAVs present some technical handicaps, such as limited cargo capacity and possible immunogenicity in repetitive doses. The development of alternative, non-viral delivery platforms like nanoparticles is of great interest to extend the application of gene therapy for RP.

METHODS

Amino-functionalized mesoporous silica-based nanoparticles (N-MSiNPs) were synthesized, physico-chemically characterized, and evaluated as gene delivery systems for human cells in vitro and for retinal cells in vivo. Transgene expression was evaluated by WB and immunofluorescence. The safety evaluation of mice subjected to subretinal injection was assessed by ophthalmological tests (electroretinogram, funduscopy, tomography, and optokinetic test).

RESULTS

N-MSiNPs delivered transgenes to human cells in vitro and to retinal cells in vivo. No adverse effects were detected for the integrity of the retinal tissue or the visual function of treated eyes. N-MSiNPs were able to deliver a therapeutic transgene candidate for RP, PRPF31, both in vitro and in vivo.

CONCLUSIONS

N-MSiNPs are safe for retinal delivery and thus a potential alternative to viral vectors.

Albumin-Embellished Arsenic Trioxide-Loaded Polymeric Nanoparticles Enhance Tumor Accumulation and Anticancer Efficacy via Transcytosis for Hepatocellular Carcinoma Therapy

Arsenic trioxide (ATO) has efficient anticancer effect on hepatocellular carcinoma (HCC) in clinical trials, but its off-target distribution and side effects have limited its use. Here, we demonstrate an albumin-embellished ATO-loaded polyethylene glycol-polycaprolactone-polyethyleneimine (PEG-PCL-PEI) nanoparticle (AATONP) to enhance the tumor distribution and intratumor drug release of ATO for HCC therapy. AATONP is prepared by surface embellishment with albumin on the cationic ATO-loaded PEG-PCL-PEI nanoparticles (CATONP). Albumin embellishment can reduce the cationic material's hemolytic toxicity in blood cells while maintaining the rapid internalization and lysosome escape abilities of the positively charged CATONP. AATONP provides sustained and low pH-responsive drug release, facilitating the targeted drug release in the intratumor acidic microenvironment. Moreover, AATONP can significantly improve the circulation time and tumor distribution of ATO via albumin-mediated transcytosis in HCC tumor-bearing mice. Compared with free ATO and the clinically used nanomedicine Genexol/PM, AATONP shows potent antitumor activity against a human HCC xenograft mouse model, leading to a higher tumor inhibition rate of 89.4% in HCC therapy. In conclusion, this work presents an efficient strategy to achieve tumor accumulation and the intratumor drug release of ATO for HCC therapy. An albumin-embellished arsenic trioxide (ATO)-loaded polyethylene glycol-polycaprolactone-polyethyleneimine nanoparticle (AATONP) is designed to enhance tumor distribution and intratumor drug release of ATO for hepatocellular carcinoma therapy. AATONP can achieve enhanced tumor distribution via albumin-mediated transcytosis and exhibit intratumor drug release of ATO via tumor acidic microenvironment-response, leading to potent antitumor activity.

“Pincer movement”: Reversing cisplatin resistance based on simultaneous glutathione depletion and glutathione S-transferases inhibition by redox-responsive degradable organosilica hybrid nanoparticles

The therapeutic efficacy of cisplatin has been restricted by drug resistance of cancers. Intracellular glutathione (GSH) detoxification of cisplatin under the catalysis of glutathione S-transferases (GST) plays important roles in the development of cisplatin resistance. Herein, a strategy of “pincer movement” based on simultaneous GSH depletion and GST inhibition is proposed to enhance cisplatin-based chemotherapy. Specifically, a redox-responsive nanomedicine based on disulfide-bridged degradable organosilica hybrid nanoparticles is developed and loaded with cisplatin and ethacrynic acid (EA), a GST inhibitor. Responding to high level of intracellular GSH, the hybrid nanoparticles can be gradually degraded due to the break of disulfide bonds, which further promotes drug release. Meanwhile, the disulfide-mediated GSH depletion and EA-induced GST inhibition cooperatively prevent cellular detoxification of cisplatin and reverse drug resistance. Moreover, the nanomedicine is integrated into microneedles for intralesional drug delivery against cisplatin-resistant melanoma. The in vivo results show that the nanomedicine-loaded microneedles can achieve significant GSH depletion, GST inhibition, and consequent tumor growth suppression. Overall, this research provides a promising strategy for the construction of new-type nanomedicines to overcome cisplatin resistance, which extends the biomedical application of organosilica hybrid nanomaterials and enables more efficient chemotherapy against drug-resistant cancers.

Mesoporous Biodegradable Magnesium Phosphate-Citrate Nanocarriers Amplify Methotrexate Anticancer Activity in HeLa Cells

We present the synthesis of amorphous, mesoporous, colloidal magnesium phosphate-citrate nanoparticles (MPCs) from biogenic precursors, resulting in a biocompatible and biodegradable nanocarrier that amplifies the action of the anticancer drug methotrexate (MTX). Synthesis conditions were gradually tuned to investigate the influence of the chelating agent citric acid on the colloidal stability and the mesoporosity of the obtained nanoparticles. With optimized synthesis conditions, a large BET surface area of 560 m²/g was achieved. We demonstrate the potential of these biocompatible and biodegradable mesoporous MPCs as a drug delivery system. Lipid-coated MPCs were used to load the fluorescent dye calcein and the chemotherapeutic agent MTX into the mesopores. In vitro experiments show very low premature release of the cargo but efficient stimuli-responsive release in an environment of pH 5.5, in which MPCs degrade. Lipid-coated MPCs are taken up by cancer cells and are nontoxic up to concentrations of 100 μg/mL. When loaded with MTX serving as a representative model drug for in vitro studies, MPCs induced efficient cell death with an IC₅₀ value of 1.1 μg/mL. Compared to free MTX, its delivery with MPCs enhances its efficiency by an order of magnitude. In summary, we have developed a biodegradable nanomaterial synthesized from biocompatible precursors that are neither toxic by themselves nor in the form of nanoparticles. With these features, MPCs may be applied as drug delivery systems and have the potential to reduce the side effects of current chemotherapies.

Multifunctional Role of Silica in Pharmaceutical Formulations

Due to the high surface area, adjustable surface and pore structures, and excellent biocompatibility, nano- and micro-sized silica have certainly attracted the attention of many researchers in the medical fields. This review focuses on the multifunctional roles of silica in different pharmaceutical formulations including solid preparations, liquid drugs, and advanced drug delivery systems. For traditional solid preparations, it can improve compactibility and flowability, promote disintegration, adjust hygroscopicity, and prevent excessive adhesion. As for liquid drugs and preparations, like volatile oil, ethers, vitamins, and self-emulsifying drug delivery systems, silica with adjustable pore structures is a good adsorbent for solidification. Also, silica with various particle sizes, surface characteristics, pore structure, and surface modification controlled by different synthesis methods has gained wide attention owing to its unparalleled advantages for drug delivery and disease diagnosis. We also collate the latest pharmaceutical applications of silica sorted out by formulations. Finally, we point out the thorny issues for application and survey future trends pertaining to silica in an effort to provide a comprehensive overview of its future development in the medical fields. Graphical Abstract.

Single-step acid-catalyzed synthesis of luminescent colloidal organosilica nanobeads

We present a single-step, room-temperature synthesis of fluorescent organosilica nanobeads (FOS NBs). The FOS NBs were synthesized under aqueous conditions using (3-aminopropyl)triethoxysilane (APTES) as the silicon source in the presence of L-ascorbic acid (L-AA). In the APTES/L-AA/water ternary phase, the hydrolysis and condensation reaction of APTES occurred under acidic conditions to form spherical FOS NBs with an average diameter of 426.8 nm. FOS NBs exhibit excellent colloidal stability in aqueous media. The formation of FOS NBs was complete within a 10 min reaction time, which indicates potential for large-scale mass-production synthesis of luminescent colloidal NBs. The FOS NBs exhibited blue photoluminescence (PL) under UV excitation in the absence of an additional high temperature calcination process or with the incorporation of any fluorophores. This phenomenon is attributed to the presence of carbon-containing defects, which act as luminescent centers formed by the reaction between amino groups in the APTES and L-ascorbic acid reductant. Finally, the results of a cytotoxicity test and cellular uptake experiments revealed that the FOS NBs showed potential as optical contrast agents for bioimaging.

Identification of Molecular Fragments in Equilibrium with Polysiloxane Ultrasmall Nanoparticles

During recent decades, ultrasmall inorganic nanoparticles have attracted considerable interest due to their favorable biodistribution, pharmacokinetics and theranostic properties. In particular, AGuIX nanoparticles made of polysiloxane and gadolinium chelates were successfully translated to the clinics. In an aqueous medium, these nanoparticles are in dynamic equilibrium with polysiloxane fragments due to the hydrolysis of Si-O-Si bonds. Thanks to high-performance liquid chromatography coupled with electrospray ionization mass spectrometry, all these fragments were separated and identified.

The Landscape of Nanovectors for Modulation in Cancer Immunotherapy

Immunotherapy represents a promising strategy for the treatment of cancer, which functions via the reprogramming and activation of antitumor immunity. However, adverse events resulting from immunotherapy that are related to the low specificity of tumor cell-targeting represent a limitation of immunotherapy's efficacy. The potential of nanotechnologies is represented by the possibilities of immunotherapeutical agents being carried by nanoparticles with various material types, shapes, sizes, coated ligands, associated loading methods, hydrophilicities, elasticities, and biocompatibilities. In this review, the principal types of nanovectors (nanopharmaceutics and bioinspired nanoparticles) are summarized along with the shortcomings in nanoparticle delivery and the main factors that modulate efficacy (the EPR effect, protein coronas, and microbiota). The mechanisms by which nanovectors can target cancer cells, the tumor immune microenvironment (TIME), and the peripheral immune system are also presented. A possible mathematical model for the cellular communication mechanisms related to exosomes as nanocarriers is proposed.

Role of Silica Nanoparticles in Abiotic and Biotic Stress Tolerance in Plants: A Review

The demand for agricultural crops continues to escalate with the rapid growth of the population. However, extreme climates, pests and diseases, and environmental pollution pose a huge threat to agricultural food production. Silica nanoparticles (SNPs) are beneficial for plant growth and production and can be used as nanopesticides, nanoherbicides, and nanofertilizers in agriculture. This article provides a review of the absorption and transportation of SNPs in plants, as well as their role and mechanisms in promoting plant growth and enhancing plant resistance against biotic and abiotic stresses. In general, SNPs induce plant resistance against stress factors by strengthening the physical barrier, improving plant photosynthesis, activating defensive enzyme activity, increasing anti-stress compounds, and activating the expression of defense-related genes. The effect of SNPs on plants stress is related to the physical and chemical properties (e.g., particle size and surface charge) of SNPs, soil, and stress type. Future research needs to focus on the “SNPs–plant–soil–microorganism” system by using omics and the in-depth study of the molecular mechanisms of SNPs-mediated plant resistance.

Calcium phosphate and silicate-based nanoparticles: history and emerging trends

Bulk calcium phosphates and silicate-based bioglasses have been extensively studied since the early 1970s due to their unique capacity to bind to host bone, which led to their clinical translation and commercialization in the 1980s. Since the mid-1990s, researchers have synthesized nanoscale calcium phosphate and silicate-based particles of increased specific surface area, chemical reactivity and solubility which offer specific advantages as compared to their bulk counterparts. This review provides a critical perspective on the history and emerging trends of these two classes of ceramic nanoparticles. Their synthesis and functional properties in terms of particle composition, size, shape, charge, dispersion, and toxicity are discussed as a function of relevant processing parameters. Specifically, emerging trends such as the influence of ion doping and mesoporosity on the biological and pharmaceutical performance of these nanoparticles are reviewed in more detail. Finally, a broad comparative overview is provided on the physicochemical properties and applicability of calcium phosphate and silicate-based nanoparticles within the fields of i) local delivery of therapeutic agents, ii) functionalization of biomaterial scaffolds or implant coatings, and iii) bio-imaging applications.

An update on microneedle-based systems for diabetes

Diabetes is one of the most serious chronic diseases today. Patients with diabetes need frequent insulin injections or blood sampling to monitor blood glucose levels. The microneedles are a painless transdermal drug delivery system, which has great advantages in achieving self-management. There have been a lot of researches on microneedles used in diabetes treatment. Microneedle-based treatment of diabetes has also changed from a simple and reliable system to a complex and efficient system. This review introduces microfluidic, glucose response, and other contents based on microneedles, and some challenges in the development of microneedles.

Self-Delivery Ternary Bioregulators for Photodynamic Amplified Immunotherapy by Tumor Microenvironment Reprogramming

Abnormal metabolism of cancer cells results in complex tumor microenvironments (TME), which play a dominant role in tumor metastasis. Herein, self-delivery ternary bioregulators (designated as TerBio) are constructed for photodynamic amplified immunotherapy against colorectal cancer by TME reprogramming. Specifically, carrier-free TerBio are prepared by the self-assembly of chlorine e6, SB505124 (SB), and lonidamine (Lon), which exhibit improved tumor accumulation, tumor penetration, and cellular uptake behaviors. Interestingly, TerBio-mediated photodynamic therapy (PDT) could not only inhibit the primary tumor growth but also induce immunogenic cell death of tumors to activate the cascade immune response. Furthermore, TerBio are capable of TME reprograming by SB-triggered transforming growth factor (TGF)-β blockage and Lon-induced lactic acid efflux inhibition. As a consequence, TerBio significantly suppresses distant and metastatic tumor growth by PDT-amplified immunotherapy. This study might advance the development of self-delivery nanomedicine against malignant tumor growth and metastasis.

One-Pot Bifunctionalization of Silica Nanoparticles Conjugated with Bioorthogonal Linkers: Application in Dual-modal Imaging

Covalent surface modification of silica nanoparticles (SNPs) offers great potential for the development of multimodal nanomaterials for biomedical applications. Herein, we report the synthesis of covalently conjugated bifunctional SNPs and...

Bioorthogonal Disassembly of Tetrazine Bearing Supramolecular Assemblies Inside Living Cells

Supramolecular assemblies are an emerging class of nanomaterials for drug delivery systems (DDS), while their unintended retention in the biological milieu remains largely unsolved. To realize the prompt clearance of supramolecular assemblies, the bioorthogonal reaction to disassemble and clear the supramolecular assemblies within living cells is investigated here. A series of tetrazine-capped assembly precursors which can self-assemble into nanofibers and hydrogels upon enzymatic dephosphorylation are designed. Such an enzyme-instructed supramolecular assembly process can perform intracellularly. The time-dependent accumulation of assemblies elicits oxidative stress and induces cellular toxicity. Tetrazine-bearing assemblies react with trans-cyclooctene derivatives, which lead to the disruption of π-π stacking and induce disassembly. In this way, the intracellular self-assemblies disassemble and are deprived of potency. This bioorthogonal disassembly strategy leverages the biosafety aspect in developing nanomaterials for DDSs.

Efficiency of mesoporous silica/carboxymethyl β-glucan as a fungicide nano-delivery system for improving chlorothalonil bioactivity and reduce biotoxicity

Understanding the lethal effects of pesticides nano formulations on the targeted organisms (pathogens) and the non-targeted organisms (fish, earthworms, etc) is essential in assessing the probable impact of new technologies on agriculture and environment. Here we evaluated the bioactivity and the biotoxicity of new type of fungicide smart-delivery formulation based on conjugating carboxymethylated-β-glucans on the mesoporous silica nanoparticles (MSNs) surface after loading chlorothalonil (CHT) fungicide in the MSNs pores. The obtained formulation has been characterized with FE-SEM, and HR-TEM. The CHT loading efficiency has been measured with TGA. The bioactivity of the obtained formulation (CHT@MSNs-β-glucans) has been tested against four pathogens, fusarium head blight (Fusarium graminearum), sheath rot (Sarocladium oryzae), rice sheath blight (Rhizoctonia solani), and soyabean anthracnose (Colletotrichum truncatum) compared with CHT WP 75% commercial formulation (CHT-WP) and technical CHT. The environmental biotoxicity of CHT@MSNs-β-glucans compared with CHT-WP has been tested toward earthworm (Eisenia fetida) and zebra fish (Danio rerio). The results showed that CHT@MSNs-β-glucans has an excellent bioactivity against the subjected pathogens with better inhabiting effects than CHT-WP. CHT@MSNs-β-glucans toxicity to Eisenia fetida was found 2.25 times lower than CHT-WP toxicity. The LC₅₀ of CHT@MSNs-β-glucans to zebra fish after the first 24h was 2.93 times higher than CHT-WP. After 96h of treatment, the LC₅₀ of CHT@MSNs-β-glucans was 2.66 times higher than CHT-WP. This work highlighted the necessity to increase the mandatory bioassays of nano formulations with the major non-target organisms in the environmental risk assessment of new pesticide formulations.

Silica-encapsulated DNA tracers for measuring aerosol distribution dynamics in real-world settings

Aerosolized particles play a significant role in human health and environmental risk management. The global importance of aerosol-related hazards, such as the circulation of pathogens and high levels of air pollutants, have led to a surging demand for suitable surrogate tracers to investigate the complex dynamics of airborne particles in real-world scenarios. In this study, we propose a novel approach using silica particles with encapsulated DNA (SPED) as a tracing agent for measuring aerosol distribution indoors. In a series of experiments with a portable setup, SPED were successfully aerosolized, recaptured, and quantified using quantitative polymerase chain reaction (qPCR). Position dependency and ventilation effects within a confined space could be shown in a quantitative fashion achieving detection limits below 0.1 ng particles per m³ of sampled air. In conclusion, SPED show promise for a flexible, cost-effective, and low-impact characterization of aerosol dynamics in a wide range of settings.

Chronology of Global Success: 20 Years of Prof Vallet-Regí Solving Questions

Twenty years ago, a group of bold scientists led by Prof Vallet-Regí suggested for the first time the use of mesoporous materials as potential drug delivery systems. Without knowing it; these pioneers unleashed the beast of creativity around the world because that original idea has been the inspiration of hundreds of scientific groups for the design of many versatile delivery systems based on mesoporous materials. Because the dream is not the destination, it is the journey, the present review aims to summarise the chain of events that catapulted a small and young research team from the grassroots of academia to the elite of the Biomedical Engineering field.

Recent advanced development of metal-loaded mesoporous organosilicas as catalytic nanoreactors

Ordered periodic mesoporous organosilicas have been widely applied in adsorption/separation/sensor technologies and the fields of biomedicine/biotechnology as well as catalysis. Crucially, surface modification with functional groups and metal complexes or nanoparticle loading has ensured high efficacy and efficiency. This review will highlight the current state of design and catalytic application of transition metal-loaded mesoporous organosilica nanoreactors. It will outline prominent synthesis approaches for the grafting of metal complexes, metal salt adsorption and in situ preparation of metal nanoparticles, and summarize the catalytic performance of the resulting mesoporous organosilica hybrid materials. Finally, the potential prospects and challenges of metal-loaded mesoporous organosilica nanoreactors are addressed.

Stable Encapsulation of Methylene Blue in Polysulfide Organosilica Colloids for Fluorescent Tracking of Nanoparticle Uptake in Cells

Methylene blue (MB), a century-old drug and a fluorescent dye, has a long history of diverse applications, both in drug therapy and as a tissue-staining agent. However, MB is inherently unstable when exposed to light and reducing agents. In this study, we aim to prepare and characterize polysulfide-based organosilica colloidal particles for efficient, stable, and protective encapsulation of MB. Disulfide- and tetrasulfide-containing organosilane congeners were used as organosilica precursors for direct synthesis of organosilica colloids based on the silica ouzo effect. MB was spontaneously entrapped into the colloidal particles during the particle formation process. The following properties of the colloidal MB were evaluated: particle size, surface charge, atomic distribution, encapsulation efficiency, MB release, photodynamic activity, thiol and ascorbate reactivity, and cytotoxicity. The DLS measurements show that the size of colloidal MB is tunable in a range of 100 nm to 1 μm. SEM images reveal spherical particles with composition-dependent particle sizes of 70-120 nm (coefficient of variation: 15-18%). MB was encapsulated in the colloidal particles with a maximal efficiency of 95%. The release of MB from the colloids was <1% at 4 h and <3.5% at 48 h. The colloidal particles show much reduced photodynamic activity, low reactivity toward reducing agents, and low cytotoxicity. Accordingly, the colloidal MB was proposed and further investigated as a fluorescent particle tracer for the study of cell-nanoparticle interactions. In conclusion, MB can be efficiently and stably loaded into polysulfide organosilica colloidal particles using a simple and convenient physical route.

Nanoparticle delivery of recombinant IL-2 (BALLkine-2) achieves durable tumor control with less systemic adverse effects in cancer immunotherapy

Recent strategies in cancer immunotherapy based on interleukin-2 (IL-2) are generally focused on reducing regulatory T cell (Treg) development by modifying IL-2 receptor alpha (IL-2Rα) domain. However, the clinical utility of high-dose IL-2 treatment is mainly limited by severe systemic toxicity. We find that peritumorally injectable 'BALLkine-2', recombinant human IL-2 (rIL-2) loaded porous nanoparticle, dramatically reduces systemic side effects of rIL-2 by minimizing systemic IL-2 exposure. Notably, in cynomolgus monkeys, subcutaneous (SC)-injection of BALLkine-2 not only dramatically reduces systemic circulation of rIL-2 in the blood, but also increases half-life of IL-2 compared to IV- or SC-injection of free rIL-2. Peritumorally-injected BALLkine-2 enhances intratumoral lymphocyte infiltration without inducing Treg development and more effectively synergizes with PD-1 blockade than high-dose rIL-2 administration in B16F10 melanoma model. BALLkine-2 could be a highly potent therapeutic option due to higher anti-tumor efficacy with lower and fewer doses and reduced systemic toxicity compared to systemic rIL-2.

Recent developments in mesoporous polydopamine-derived nanoplatforms for cancer theranostics

Polydopamine (PDA), which is derived from marine mussels, has excellent potential in early diagnosis of diseases and targeted drug delivery owing to its good biocompatibility, biodegradability, and photothermal conversion. However, when used as a solid nanoparticle, the application of traditional PDA is restricted because of the low drug-loading and encapsulation efficiencies of hydrophobic drugs. Nevertheless, the emergence of mesoporous materials broaden our horizon. Mesoporous polydopamine (MPDA) has the characteristics of a porous structure, simple preparation process, low cost, high specific surface area, high light-to-heat conversion efficiency, and excellent biocompatibility, and therefore has gained considerable interest. This review provides an overview of the preparation methods and the latest applications of MPDA-based nanodrug delivery systems (chemotherapy combined with radiotherapy, photothermal therapy combined with chemotherapy, photothermal therapy combined with immunotherapy, photothermal therapy combined with photodynamic/chemodynamic therapy, and cancer theranostics). This review is expected to shed light on the multi-strategy antitumor therapy applications of MPDA-based nanodrug delivery systems.

Redox-Responsive Molecularly Imprinted Nanoparticles for Targeted Intracellular Delivery of Protein toward Cancer Therapy

Although protein therapeutics is of significance in therapeutic intervention of cancers, controlled delivery of therapeutic proteins still faces substantial challenges including susceptibility to degradation and denaturation and poor membrane permeability. Herein, we report a sialic acid (SA)-imprinted biodegradable silica nanoparticles (BS-NPs)-based protein delivery strategy for targeted cancer therapy. Cytotoxic ribonuclease A (RNase A) was effectively caged in the matrix of disulfide-hybridized silica NPs (encapsulation efficiency of ∼64%), which were further functionalized with cancer targeting capability via surface imprinting with SA as imprinting template. Such nanovectors could not only maintain high stability in physiological conditions but also permit redox-triggered biodegradation for both concomitant release of the loaded therapeutic cargo and in vivo clearance. In vitro experiments confirmed that the SA-imprinted RNase A@BS-NPs could selectively target SA-overexpressed tumor cells, promote cells uptake, and subsequently be cleaved by intracellular glutathione (GSH), resulting in rapid release kinetics and enhanced cell cytotoxicity. In vivo experiments further confirmed that the SA-imprinted RNase A@BS-NPs had specific tumor-targeting ability and high therapeutic efficacy of RNase A in xenograft tumor model. Due to the specific targeting and traceless GSH-stimulated intracellular protein release, the SA-imprinted BS-NPs provided a promising platform for the delivery of biomacromolecules in cancer therapy.

Mesoporous Silica Nanoparticle-Based Imaging Agents for Hepatocellular Carcinoma Detection

Hepatocellular carcinoma (HCC) is characterized by poor prognosis and high mortality. The treatment of HCC is closely related to the stage, and the early-stage of HCC patients usually accompanies a more long-term survival rate after clinical treatment. Hence, there are critical needs to develop effective imaging agents with superior diagnostic precision for HCC detection at an early stage. Recently, mesoporous silica nanoparticles (MSNs) based imaging agents have gained extensive attentions in HCC detection, which can serve as a multifunctional nanoplatform with controllable size and facile surface functionalization. This perspective summarizes recent advances in MSNs based imaging agents for HCC detection by the incorporation of several clinical imaging modalities. Multi-modal imaging system has been developed for higher spatial resolution and sensitivity. Even though some limitations and challenges need to be overcome, we envision the development of novel MSNs based imaging agents will offer great potential applications in clinical HCC detection.

Bioinspired Silicification of mRNA-Loaded Polyion Complexes for Macrophage-Targeted mRNA Delivery

In vitro transcribed messenger RNA (mRNA) delivery to macrophages is a promising therapeutic modality for inflammatory diseases because it can modulate the immunological activity of macrophages. However, efficient macrophage-targeted mRNA delivery remains challenging. Herein, we fabricated silica-coated polyion complexes (PICs), termed SilPICs, via bioinspired silicification for stable encapsulation of mRNA and scavenger receptor (SR)-mediated macrophage targeting. Silica coating was readily performed by simply mixing mRNA-loaded PICs with tetramethyl orthosilicate in aqueous media at 25 °C. The silica shell formation was verified by a slight increase in size (∼18 nm), a conversion of ζ-potential from positive (+22 mV) to negative (-23 mV), the peak appearance derived from silanol groups and siloxane bonds in the IR spectra, and elemental analyses by scanning transmission electron microscopy-energy-dispersive X-ray spectrometry (STEM-EDS). The silica shell efficiently protected the mRNA payload from enzymatic degradation in a fetal bovine serum-containing medium. Meanwhile, the reversibility of the silica shell allowed mRNA release from SilPICs after silica dissolution into silicic acids under diluted conditions. Furthermore, SilPICs elicited 20-fold higher mRNA transfection efficiency in the macrophage cell line RAW264.7 compared to noncoated PICs, presumably due to the facilitated cellular internalization by the silica shell. These enhancements were compromised in the RAW264.7 cells incubated with dextran sulfate and poly(inosinic acid) as inhibitors of SR type A1 and were not observed in cultured CT26 colon cancer cells, which are SR-negative cells. Collectively, SilPIC is a promising mRNA delivery vehicle with both mRNA protectability and macrophage targetability.

A Modular Biomaterial Scaffold-Based Vaccine Elicits Durable Adaptive Immunity to Subunit SARS-CoV-2 Antigens

The coronavirus disease 2019 (COVID-19) pandemic demonstrates the importance of generating safe and efficacious vaccines that can be rapidly deployed against emerging pathogens. Subunit vaccines are considered among the safest, but proteins used in these typically lack strong immunogenicity, leading to poor immune responses. Here, a biomaterial COVID-19 vaccine based on a mesoporous silica rods (MSRs) platform is described. MSRs loaded with granulocyte-macrophage colony-stimulating factor (GM-CSF), the toll-like receptor 4 (TLR-4) agonist monophosphoryl lipid A (MPLA), and SARS-CoV-2 viral protein antigens slowly release their cargo and form subcutaneous scaffolds that locally recruit and activate antigen-presenting cells (APCs) for the generation of adaptive immunity. MSR-based vaccines generate robust and durable cellular and humoral responses against SARS-CoV-2 antigens, including the poorly immunogenic receptor binding domain (RBD) of the spike (S) protein. Persistent antibodies over the course of 8 months are found in all vaccine configurations tested and robust in vitro viral neutralization is observed both in a prime-boost and a single-dose regimen. These vaccines can be fully formulated ahead of time or stored lyophilized and reconstituted with an antigen mixture moments before injection, which can facilitate its rapid deployment against emerging SARS-CoV-2 variants or new pathogens. Together, the data show a promising COVID-19 vaccine candidate and a generally adaptable vaccine platform against infectious pathogens.

MoS2-based nanocomposites for cancer diagnosis and therapy

Molybdenum is a trace dietary element necessary for the survival of humans. Some molybdenum-bearing enzymes are involved in key metabolic activities in the human body (such as xanthine oxidase, aldehyde oxidase and sulfite oxidase). Many molybdenum-based compounds have been widely used in biomedical research. Especially, MoS2-nanomaterials have attracted more attention in cancer diagnosis and treatment recently because of their unique physical and chemical properties. MoS2 can adsorb various biomolecules and drug molecules via covalent or non-covalent interactions because it is easy to modify and possess a high specific surface area, improving its tumor targeting and colloidal stability, as well as accuracy and sensitivity for detecting specific biomarkers. At the same time, in the near-infrared (NIR) window, MoS2 has excellent optical absorption and prominent photothermal conversion efficiency, which can achieve NIR-based phototherapy and NIR-responsive controlled drug-release. Significantly, the modified MoS2-nanocomposite can specifically respond to the tumor microenvironment, leading to drug accumulation in the tumor site increased, reducing its side effects on non-cancerous tissues, and improved therapeutic effect. In this review, we introduced the latest developments of MoS2-nanocomposites in cancer diagnosis and therapy, mainly focusing on biosensors, bioimaging, chemotherapy, phototherapy, microwave hyperthermia, and combination therapy. Furthermore, we also discuss the current challenges and prospects of MoS2-nanocomposites in cancer treatment.

Evaluation of the Effect of Inactivated Transmissible Gastroenteritis Virus Vaccine with Nano Silicon on the Phenotype and Function of Porcine Dendritic Cells

A transmissible gastroenteritis virus (TGEV) is a porcine enteropathogenic coronavirus, causing acute swine enteric disease especially in suckling piglets. Mesoporous silica nanoparticles (MSNs) are safe vaccine adjuvant, which could enhance immune responses. Our previous research confirmed that nano silicon had immune-enhancing effects with inactivated TGEV vaccine. In this study, we further clarified the immune-enhancing mechanism of the inactivated TGEV vaccine with MSNs on porcine dendritic cells (DCs). Our results indicated that the inactivated TGEV vaccine with MSNs strongly enhanced the activation of the DCs. Expressions of TLR3, TLR5, TLR7, TLR9, and TLR10, cytokines IFN-α, IL-1β, IL-6, IL-12, and TNF-α, cytokine receptor CCR-7 of immature DCs were characterized and showed themselves to be significantly higher in the inactivated TGEV vaccine with the MSN group. In summary, the inactivated TGEV vaccine with MSNs has effects on the phenotype and function of porcine DCs, which helps to better understand the immune-enhancing mechanism.

Atypical Renal Clearance of Nanoparticles Larger Than the Kidney Filtration Threshold

In recent years, several publications reported that nanoparticles larger than the kidney filtration threshold were found intact in the urine after being injected into laboratory mice. This theoretically should not be possible, as it is widely known that the kidneys prevent molecules larger than 6–8 nm from escaping into the urine. This is interesting because it implies that some nanoparticles can overcome the size limit for renal clearance. What kinds of nanoparticles can “bypass” the glomerular filtration barrier and cross into the urine? What physical and chemical characteristics are essential for nanoparticles to have this ability? And what are the biomolecular and cellular mechanisms that are involved? This review attempts to answer those questions and summarize known reports of renal-clearable large nanoparticles.

Charge-reversal biodegradable MSNs for tumor synergetic chemo/photothermal and visualized therapy

Given the difficulties of biodegradation of mesoporous silica nanoparticles (NPs), enrichment and penetration of tumor sites, and real-time monitoring of the treatment process, we developed a kind of mannose-doping doxorubicin-loading mesoporous silica nanoparticle (MSN-Man-DOX) and coated by polydopamine-Gd³⁺ (PDAGd) metal-phenolic networks, as well as modified by poly (2-Ethyl-2-Oxazoline) (PEOz), constructing a novel nanomedicine MSN-Man-DOX@PDA-Gd-PEOz. Its pH-responsive charge reversal, photothermal, biodegradation, drug release, and magnetic resonance imaging (MRI) properties were evaluated in vitro. Cellular uptake, tumor penetration, lysosomal escape properties, as well as cell safety and toxicity of the nanoplatform were investigated through cell experiments. Finally, the MRI, organ distribution, photothermal condition, and comprehensive anti-tumor therapy in vivo were evaluated comprehensively through animal experiments. Research results showed that MSN-Man-DOX@PDA-Gd-PEOz had outstanding tumor enrichment and penetration abilities, which can produce excellent treatment effects through the synergistic effect of chemotherapy and photothermal therapy (PTT) with the function of magnetic resonance imaging contrast agent for disease monitoring. Besides, after finishing the therapeutic effect MSN-Man-DOX@PDA-Gd-PEOz can be biodegraded, so it had a good prospect of clinical application.

Functionalized silica nanoparticles: classification, synthetic approaches and recent advances in adsorption applications

Nanotechnology is rapidly sweeping through all the vital fields of science and technology such as electronics, aerospace, defense, medicine, and catalysis. It involves the design, synthesis, characterization, and applications of materials and devices on the nanometer scale. At the nanoscale, physical and chemical properties differ from the properties of the individual atoms and molecules of bulk matter. In particular, the design and development of silica nanomaterials have captivated the attention of several researchers worldwide. The applications of hybrid silicas are still limited by the lack of control on the morphology and particle size. The ability to control both the size and morphology of the materials and to obtain nano-sized silica particles has broadened the spectrum of applications of mesoporous organosilicas and/or has improved their performances. On the other hand, adsorption is a widely used technique for the separation and removal of pollutants (metal ions, dyes, organics,...) from wastewater. Silica nanoparticles have specific advantages over other materials for adsorption applications due to their unique structural characteristics: a stable structure, a high specific surface area, an adjustable pore structure, the presence of silanol groups on the surface which allow easy modification, less environmental harm, simple synthesis, low cost, etc. Silica nanoparticles are potential adsorbents for pollutants. We present herein an overview of the different types of silica nanoparticles going from the definitions to properties, synthetic approaches and the mention of potential applications. We focus mainly on the recent advances in the adsorption of different target substances (metal ions, dyes and other organics).

Antibacterial Activity and Iron Release of Organic-Inorganic Hybrid Biomaterials Synthesized via the Sol-Gel Route

The aim of this work was the synthesis of hybrid materials of iron (II)-based therapeutic systems via the sol-gel method. Increasing amounts of polyethylene glycol (PEG 6, 12, 24, 50 wt%) were added to SiO2/Fe20 wt% to modulate the release kinetics of the drug from the systems. Fourier-transform infrared (FTIR) spectroscopy was used to study the interactions between different components in the hybrid materials. The release kinetics in a simulated body fluid (SBF) were investigated, and the amount of Fe2+ released was detected via ultraviolet-visible spectroscopy (UV-Vis) after reaction with ortho-phenanthroline. Furthermore, biological characterization was carried out. The bioactivity of the synthesized hybrid materials was evaluated via the formation of a layer of hydroxyapatite on the surface of samples soaked in SBF using spectroscopy. Finally, the potential antibacterial properties of seven different materials against two different bacteria—E. coli and S. aureus—were investigated.

Droplet Formation and Growth Mechanisms in Reaction-Induced Spontaneous Emulsification of 3-(Trimethoxysilyl) Propyl Methacrylate

Spontaneous emulsification of 3-(trimethoxysilyl) propyl methacrylate (TPM) can produce complex and active colloids, nanoparticles, or monodisperse Pickering emulsions. Despite the applicability of TPM in particle synthesis, the nucleation and growth mechanisms of TPM emulsions are still poorly understood. We investigate droplet formation and growth of TPM in aqueous solutions under quiescent conditions. Our results show that in the absence of stirring the mechanisms of diffusion and stranding likely drive the spontaneous emulsification of TPM through the formation of co-soluble species during hydrolysis. In addition, turbidity and dynamic light scattering experiments show that the pH modulates the growth mechanism. At pH 10.1, the droplets grow via Ostwald ripening, while at pH 11.5, the droplets grow via monomer addition. Adding surfactants [Tween, sodium dodecyl sulfate (SDS), or cetyltrimethylammonium bromide] leads to <100 nm droplets that are kinetically stable. The growth of Tween droplets occurs through addition of TPM species while the number density of droplets is kept constant. In addition, in the presence of the ionic surfactant SDS, electrostatic repulsion between the solubilized TPM species and SDS leads to a significant increase in the number density of droplets as well as additional nucleation events. Finally, imaging of the solubilization of TPM in capillaries shows that in the absence of a surfactant, TPM hydrolysis is likely the rate-limiting step for emulsification, whereas the presence of silica particles in the aqueous phase likely acts as a catalyst of TPM hydrolysis. Our experiments highlight the importance of diffusion and solubilization of TPM species in the aqueous phase in the nucleation and growth of droplets.

Biodegradable Small-Scale Swimmers for Biomedical Applications

Most forms of biomatter are ephemeral, which means they transform or deteriorate after a certain time. From this perspective, implantable healthcare devices designed for temporary treatments should exhibit the ability to degrade and either blend in with healthy tissues, or be cleared from the body with minimal disruption after accomplishing their designated tasks. This topic is currently being investigated in the field of biomedical micro- and nanoswimmers. These tiny devices have the ability to move through fluids by converting physical or chemical energy into motion. Several architectures of these devices have been designed to mimic the motion strategies of nature's motile microorganisms and cells. Due to their motion abilities, these devices have been proposed as minimally invasive tools for precision healthcare applications. Hence, a natural progression in this field is to produce motile structures that can adopt, or even surpass, similar transient features as biological systems. The fate of small-scale swimmers after accomplishing their therapeutic mission is critical for the successful translation of small-scale swimmers' technologies into clinical applications. In this review, recent research efforts are summarized on the topic of biodegradable micro- and nanoswimmers for biomedical applications, with a focus on targeted therapeutic delivery.

Application of Non-Viral Vectors in Drug Delivery and Gene Therapy

Vectors and carriers play an indispensable role in gene therapy and drug delivery. Non-viral vectors are widely developed and applied in clinical practice due to their low immunogenicity, good biocompatibility, easy synthesis and modification, and low cost of production. This review summarized a variety of non-viral vectors and carriers including polymers, liposomes, gold nanoparticles, mesoporous silica nanoparticles and carbon nanotubes from the aspects of physicochemical characteristics, synthesis methods, functional modifications, and research applications. Notably, non-viral vectors can enhance the absorption of cargos, prolong the circulation time, improve therapeutic effects, and provide targeted delivery. Additional studies focused on recent innovation of novel synthesis techniques for vector materials. We also elaborated on the problems and future research directions in the development of non-viral vectors, which provided a theoretical basis for their broad applications.

Nonresonant CARS Imaging of Porous and Solid Silicon Nanoparticles in Human Cells

Coherent anti-Stokes Raman scattering (CARS), a nonlinear optical method for rapid visualization of biological objects, represents a progressive tool in biology and medicine to explore cells and tissue structures in living systems and biopsies. In this study, we report efficient nonresonant CARS imaging of silicon nanoparticles (SiNPs) in human cells as a proof of concept. As both bulk and porous silicon exhibit a high third-order nonlinear susceptibility, χ⁽³⁾, which is responsible for the CARS intensity, it is possible to visualize the SiNPs without specific labels. Porous and solid SiNPs were obtained from layers of porous and nonporous silicon nanowires and mesoporous silicon. Electron microscopy and Raman spectroscopy showed that porous SiNPs consisted of ∼3 nm silicon nanocrystals (nc-Si) and pores, whereas solid nanoparticles comprised ∼30 nm nc-Si. All types of SiNPs were nontoxic at concentrations up to 500 μg/mL after 24 h of incubation with cells. We demonstrated that although nc-Si possesses a distinguished narrow Raman band of about 520 cm^-1, it is possible to detect a high CARS signal from SiNPs in the epi-direction even in a nonresonant regime. 3D CARS images showed that all types of studied SiNPs were visualized as bright spots inside the cytoplasm of cells after 3-6 h of incubation because of the contrast provided by the high third-order nonlinear susceptibility of SiNPs, which is 1 × 10⁴ to 1 × 10⁵ times higher than that of water and typical biological media. Overall, CARS microscopy can provide localization of SiNPs within biological structures at the cellular level and can be a powerful tool for in vitro monitoring of silicon-based drug delivery systems or use SiNPs as labels to monitor various bioprocesses inside living cells.

Highly Sensitive Fluorescent pH Microsensors Based on the Ratiometric Dye Pyranine Immobilized on Silica Microparticles

Pyranine (HPTS) is a remarkably interesting pH-sensitive dye that has been used for plenty of applications. Its high quantum yield and extremely sensitive ratiometric fluorescence against pH change makes it a very favorable for pH-sensing applications and the development of pH nano-/microsensors. However, its strong negative charge and lack of easily modifiable functional groups makes it difficult to use with charged substrates such as silica. This study reports a methodology for noncovalent HPTS immobilization on silica microparticles that considers the retention of pH sensitivity as well as the long-term stability of the pH microsensors. The study emphasizes the importance of surface charge for governing the sensitivity of the immobilized HPTS dye molecules on silica microparticles. The importance of the immobilization methodology, which preserves the sensitivity and stability of the microsensors, is also assessed.

Enhanced Cancer Starvation Therapy Based on Glucose Oxidase/3-Methyladenine-Loaded Dendritic Mesoporous OrganoSilicon Nanoparticles

Cell autophagy is a well-known phenomenon in cancer, which limits the efficacy of cancer therapy, especially cancer starvation therapy. Glucose oxidase (GOx), which is considered as an attractive starvation reagent for cancer therapy, can effectively catalyze the conversion of glucose into gluconic acid and hydrogen peroxide (H2O2) in the presence of O2. However, tumor cells adapt to survive by inducing autophagy, limiting the therapy effect. Therefore, anti-cell adaptation via autophagy inhibition could be used as a troubleshooting method to enhance tumor starvation therapy. Herein, we introduce an anti-cell adaptation strategy based on dendritic mesoporous organosilica nanoparticles (DMONs) loaded with GOx and 3-methyladenine (3-MA) (an autophagy inhibition agent) to yield DMON@GOx/3-MA. This formulation can inhibit cell adaptative autophagy after starvation therapy. Our in vitro and in vivo results demonstrate that autophagy inhibition enhances the efficacy of starvation therapy, leading to tumor growth suppression. This anti-cell adaptation strategy will provide a new way to enhance the efficacy of starvation cancer therapy.

Endogenous dual stimuli-activated NO generation in the conventional outflow pathway for precision glaucoma therapy

High intraocular pressure (IOP) has been regarded as a predominant risk factor for glaucoma. Nitric oxide (NO) is shown to lower IOP, but the magnitude and duration of IOP reduction are not satisfying due to the poor cornea penetration of NO drugs and limited NO generation in the trabecular meshwork (TM)/Schlemm's canal (SC) area. Herein, we introduce deep cornea penetrating biodegradable hollow mesoporous organosilica (HOS) nanocapsules for the efficient co-delivery of hydrophobic JS-K (J_R) and hydrophilic l-Arginine (L_O). The resulting HOS-J_RL_O can be reduced and oxidized by the ascorbic acid (AA) and catalysis of endothelial nitric oxide synthase (eNOS) in the TM/SC microenvironment to release NO for inducing appreciable IOP reduction in various glaucoma mouse models. In addition to developing an endogenous stimuli-responsive NO nanotherapeutic, this study is also expected to establish a versatile, non-invasive, and efficacious treatment paradigm for precision glaucoma therapy.