Toxicity of silica nanoparticles depends on size, dose, and cell type

Design rules applied to silver nanoparticles synthesis: A practical example of machine learning application

The synthesis of silver nanoparticles with controlled physicochemical properties is essential for governing their intended functionalities and safety profiles. However, synthesis process involves multiple parameters that could influence the resulting properties. This challenge could be addressed with the development of predictive models that forecast endpoints based on key synthesis parameters. In this study, we manually extracted synthesis-related data from the literature and leveraged various machine learning algorithms. Data extraction included parameters such as reactant concentrations, experimental conditions, as well as physicochemical properties. The antibacterial efficiencies and toxicological profiles of the synthesized nanoparticles were also extracted. In a second step, based on data completeness, we employed regression algorithms to establish relationships between synthesis parameters and desired endpoints and to build predictive models. The models for core size and antibacterial efficiency were trained and validated using a cross-validation approach. Finally, the features' impact was evaluated via Shapley values to provide insights into the contribution of features to the predictions. Factors such as synthesis duration, scale of synthesis and the choice of capping agents emerged as the most significant predictors. This study demonstrated the potential of machine learning to aid in the rational design of synthesis process and paves the way for the safe-by-design principles development by providing insights into the optimization of the synthesis process to achieve the desired properties. Finally, this study provides a valuable dataset compiled from literature sources with significant time and effort from multiple researchers. Access to such datasets notably aids computational advances in the field of nanotechnology.

Antibiofilm activity of mesoporous silica nanoparticles against the biofilm associated infections

In pharmaceutical industries, various chemical carriers are present which are used for drug delivery to the correct target sites. The most popular and upcoming drug delivery carriers are mesoporous silica nanoparticles (MSN). The main reason for its popularity is its ability to be specific and optimize the drug delivery process in a controlled manner. Nowadays, MSNs are widely used to eradicate various microbial infections, especially the ones related to biofilms. Biofilms are sessile groups of cells that live by forming a consortium and exhibit antibacterial resistance (AMR). They exhibit AMR by extracellular polymeric substances (EPS) and various quorum sensing (QS) signaling molecules. Usually, bacterial and fungal cells are capable of forming biofilms. These biofilms are pathogenic. In the majority of the cases, biofilms cause nosocomial diseases. This review will focus on the antibiofilm activities of MSN, its mechanism of target-specific drug delivery, and its ability to disrupt the bacterial biofilms inhibiting the infection. The review will also discuss various mechanisms for the delivery of pharmaceutical molecules by the MSNs to inhibit the bacterial biofilms, and lastly, we will talk about the different types of MSNs and their antibiofilm activities.

Fullerene C60 Conjugate with Folic Acid and Polyvinylpyrrolidone for Targeted Delivery to Tumor Cells

The use of targeted drug delivery systems, including those based on selective absorption by certain receptors on the surface of the target cell, can lead to a decrease in the minimum effective dose and the accompanying toxicity of the drug, as well as an increase in therapeutic efficacy. A fullerene C60 conjugate (FA-PVP-C60) with polyvinylpyrrolidone (PVP) as a biocompatible spacer and folic acid (FA) as a targeting ligand for tumor cells with increased expression of folate receptors (FR) was obtained. Using 13C NMR spectroscopy, FT-IR, UV-Vis spectrometry, fluorometry and thermal analysis, the formation of the conjugate was confirmed and the nature of the binding of its components was established. The average particle sizes of the conjugate in aqueous solutions and cell culture medium were determined using dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA). The FA-PVP-C60 showed antiradical activity against •DPPH, •OH and O2•-, but at the same time, it was shown to generate 1O2. It was found that the conjugate in the studied concentration range (up to 200 μg/mL) is non-toxic in vitro and does not affect the cell cycle. To confirm the ability of the conjugate to selectively accumulate through folate-mediated endocytosis, its uptake into cells was analyzed by flow cytometry and confocal microscopy. It was shown that the conjugate is less absorbed by A549 cells with low FR expression than by HeLa, which has a high level of expression of this receptor.

Surface Modification of Mesoporous Silica Nanoparticles for Application in Targeted Delivery Systems of Antitumour Drugs

The problem of tumour therapy has attracted the attention of many researchers for many decades. One of the promising strategies for the development of new dosage forms to improve oncology treatment efficacy and minimise side effects is the development of nanoparticle-based targeted transport systems for anticancer drugs. Among inorganic nanoparticles, mesoporous silica deserves special attention due to its outstanding surface properties and drug-loading capability. This review analyses the various factors affecting the cytotoxicity, cellular uptake, and biocompatibility of mesoporous silica nanoparticles (MSNs), constituting a key aspect in the development of safe and effective drug delivery systems. Special attention is paid to technological approaches to chemically modifying MSNs to alter their surface properties. The stimuli that regulate drug release from nanoparticles are also discussed, contributing to the effective control of the delivery process in the body. The findings emphasise the importance of modifying MSNs with different surface functional groups, bio-recognisable molecules, and polymers for their potential use in anticancer drug delivery systems.

State of the Art of Silica Nanoparticles: An Overview on Biodistribution and Preclinical Toxicity Studies

Over the past few years, nanoparticles have drawn particular attention in designing and developing drug delivery systems due to their distinctive advantages like improved pharmacokinetics, reduced toxicity, and specificity. Along with other successful nanosystems, silica nanoparticles (SNPs) have shown promising effects for therapeutic and diagnostic purposes. These nanoparticles are of great significance owing to their modifiable surface with various ligands, tunable particle size, and large surface area. The rate and extent of degradation and clearance of SNPs depend on factors such as size, shape, porosity, and surface modification, which directly lead to varying toxic mechanisms. Despite SNPs' enormous potential for clinical and pharmaceutical applications, safety concerns have hindered their translation into the clinic. This review discusses the biodistribution, toxicity, and clearance of SNPs and the formulation-related factors that ultimately influence clinical efficacy and safety for treatment. A holistic view of SNP safety will be beneficial for developing an enabling SNP-based drug product.

Applications of nanomaterials in anti-VEGF treatment for ophthalmic diseases

Angiogenesis has been determined to be essential in the occurrence and metastasis of diabetic retinopathy (DR), age-related macular degeneration (AMD), retinal vein occlusion (RVO), choroidal neovascularization (CNV), retinopathy of prematurity (ROP), tumor, etc. However, the clinical use of anti-vascular endothelial growth factors (VEGF) drugs is currently limited due to its high cost, potential side effects, and need for repeated injections. In recent years, nanotechnology has shown promising results in inhibiting neovascularization and reducing reactive oxygen species (ROS) or inflammatory factors. Some nanomaterials can also act as vehicles for drug delivery, such as lipid nanoparticles and PLGA. The process of angiogenesis and its molecular mechanism are discussed in this article. At the same time, this study aims to systematically review the research progress of nanotechnology and offer more treatment options for neovascularization-related diseases in clinical ophthalmology.

Toxicity prediction of nanoparticles using machine learning approaches

Nanoparticle toxicity analysis is critical for evaluating the safety of nanomaterials due to their potential harm to the biological system. However, traditional experimental methods for evaluating nanoparticle toxicity are expensive and time-consuming. As an alternative approach, machine learning offers a solution for predicting cellular responses to nanoparticles. This study focuses on developing ML models for nanoparticle toxicity prediction. The training dataset used for building these models includes the physicochemical properties of nanoparticles, exposure conditions, and cellular responses of different cell lines. The impact of each parameter on cell death was assessed using the Gini index. Five classifiers, namely Decision Tree, Random Forest, Support Vector Machine, Naïve Bayes, and Artificial Neural Network, were employed to predict toxicity. The models' performance was compared based on accuracy, sensitivity, specificity, area under the curve, F measure, K-fold validation, and classification error. The Gini index indicated that cell line, exposure dose, and tissue are the most influential factors in cell death. Among the models tested, Random Forest exhibited the highest performance in the given dataset. Other models demonstrated lower performance compared to Random Forest. Researchers can utilize the Random Forest model to predict nanoparticle toxicity, resulting in cost and time savings for toxicity analysis.

Prospects and hazards of silica nanoparticles: Biological impacts and implicated mechanisms

With the thrive of nanotechnology, silica nanoparticles (SiNPs) have been extensively adopted in the agriculture, food, cosmetic, and even biomedical industries. Due to the mass production and use, SiNPs inevitably entered the environment, resulting in ecological toxicity and even posing a threat to human health. Although considerable investigations have been conducted to assess the toxicity of SiNPs, the correlation between SiNPs exposure and consequent health risks remains ambiguous. Since the biological impacts of SiNPs can differ from their design and application, the toxicity assessment for SiNPs may be extremely difficult. This review discussed the application of SiNPs in different fields, especially their biomedical use, and documented their potential release pathways into the environment. Meanwhile, the current process of assessing SiNPs-related toxicity on various model organisms and cell lines was also detailed, thus estimating the health threats posed by SiNPs exposure. Finally, the potential toxic mechanisms of SiNPs were also elaborated based on results obtained from both in vivo and in vitro trials. This review generally summarizes the biological effects of SiNPs, which will build up a comprehensive perspective of the application and toxicity of SiNPs.

Synthesis and Characterization of Silica, Silver-Silica, and Zinc Oxide-Silica Nanoparticles for Evaluation of Blood Biochemistry, Oxidative Stress, and Hepatotoxicity in Albino Rats

Evaluation of nanoparticles (NPs) for biomedical applications has received a lot of attention for detailed study on pharmacokinetics prior to clinical application. In this study, pure C-SiO₂ (crystalline silica) NPs and SiO₂ nanocomposites with silver (Ag) and zinc oxide (ZnO) were prepared by utilizing different synthesis routes such as sol-gel and co-precipitation techniques. The prepared NPs showed highly crystalline nature as confirmed by X-ray diffraction analysis where average crystallite sizes of 35, 16, and 57 nm for C-SiO₂, Ag-SiO₂, and ZnO-SiO₂ NPs, respectively, were calculated. Fourier transform infrared analysis confirmed the presence of functional groups related to the chemicals and procedures used for sample preparation. Due to agglomeration of the prepared NPs, the scanning electron microscope images showed large particle sizes when compared to their crystalline sizes. The optical properties of the prepared NPs such as absorption were obtained with UV-Vis spectroscopy. For in vivo biological evaluation, albino rats, both male and female, kept in different groups were exposed to NPs with 500 μg/kg dose. Hematological, serum biochemistry, histo-architecture, oxidative stress biomarkers, and antioxidant parameters in liver tissues along with various biomarkers for the evaluation of erythrocytes were estimated. The results on hemato-biochemistry, histopathological ailments, and oxidative stress parameters exhibited 95% alteration in the liver and erythrocytes of C-SiO₂ NPs-treated rats while 75 and 60% alteration in the liver tissues of rats due to exposure to Ag-SiO₂ and ZnO-SiO₂ NPs, respectively, when compared with the albino rats of the control (untreated) group. Therefore, the current study showed that the prepared NPs had adverse effects on the liver and erythrocytes causing hepatotoxicity in the albino rats in respective order C-SiO₂ > Ag SiO₂ > ZnO-SiO₂. As the C-SiO₂ NPs appeared to be the most toxic, it has been concluded that coating SiO₂ on Ag and ZnO reduced their toxicological impact on albino rats. Consequently, it is suggested that Ag-SiO₂ and ZnO-SiO₂ NPs are more biocompatible than C-SiO₂ NPs.

Hydrogeochemical factors controlling the occurrence of chronic kidney disease of unknown etiology (CKDu)

Chronic kidney disease of unknown etiology (CKDu) has posed a serious threat to human health around the world. The link between the prevalence of CKDu and groundwater geochemistry is not well understood. To identify the potential geogenic risk factors, we collected 52 groundwater samples related to CKDu (CKDu groundwater) and 18 groundwater samples related to non-CKDu (non-CKDu groundwater) from the typical CKDu prevailing areas in Sri Lanka. Results demonstrated that CKDu groundwater had significantly higher Si (average 30.1 mg/L, p < 0.05) and F^- (average 0.80 mg/L, p < 0.05) concentrations than those of non-CKDu groundwater (average 21.0 and 0.45 mg/L, respectively), indicating that Si and F^- were the potential risk factors causing CKDu. The principal hydrogeochemical process controlling local groundwater chemistry was chemical weathering of silicates in Precambrian metamorphic rocks. Groundwater samples were mostly undersaturated with respect to amorphous silica and clay minerals such as talc and sepiolite, which was conducive to silicate weathering and elevated Si concentrations in groundwater. Decreased Ca²⁺ being facilitated by calcite precipitation and cation exchange between Ca²⁺ and Na⁺ favored fluorite dissolution and thus led to high groundwater F^- concentrations. Competitive adsorption between [Formula: see text] and F^- also enhanced the release of F^- from solid surfaces. This study highlights the CKDu potential risk factors regarding groundwater geochemistry and their enrichment factors, which helps in preventing the prevalence of CKDu.

Toxicity and Impact of Silica Nanoparticles on the Configuration of Gut Microbiota in Immunodeficient Mice

Nanoparticles (NPs), having exceptional physicochemical and electrical characteristics with lower toxicity, have evolved as dynamic drug delivery carriers in living organisms. Potentially, the intragastric gavage of silica nanoparticles (SiNPs) affects gut microbiota profiles in immunodeficient mice. In this study, the impact of SiNPs of variable size and dosage was investigated in cyclophosphamide (Cy)-induced immunodeficient mice, specifically on their immune functions and gut microbiota, through physicochemical and metagenomic analysis. SiNPs of different sizes and doses were gavaged to Cy-induced immunodeficient mice for 12 days at an interval of 24 h to investigate their effects on immunological functions and the gut microbiome of mice. Our results showed that SiNPs had no significant toxicological effects on the cellular and hematological activities of immunodeficient mice. Furthermore, after the administration of different levels of SiNPs, no immune dysfunction was found in the immunosuppressed mice groups. However, gut-microbial studies and comparisons of characteristic bacterial diversity and compositions demonstrated that SiNPs significantly affect the abundance of different bacterial communities. LEfSe analysis revealed that SiNPs significantly increased the abundance of Lactobacillus, Sphingomonas, Sutterella, Akkermansia, and Prevotella, and potentially reduced Ruminococcus and Allobaculum. Thus, SiNPs significantly regulate and modify the configuration of the gut microbiota in immunodeficient mice. These dynamic variations in the intestinal bacterial community, abundance, and diversity provide new insight into the regulation and administration of silica-based NPs. This would be helpful for the further demonstration of the mechanism of action and prediction of the potential effects of SiNPs.

Magnesium Supplementation Alleviates the Toxic Effects of Silica Nanoparticles on the Kidneys, Liver, and Adrenal Glands in Rats

Concerns regarding the possible hazards to human health have been raised by the growing usage of silica nanoparticles (SiNPs) in a variety of applications, including industrial, agricultural, and medical applications. This in vivo subchronic study was conducted to assess the following: (1) the toxicity of orally administered SiNPs on the liver, kidneys, and adrenal glands; (2) the relationship between SiNPs exposure and oxidative stress; and (3) the role of magnesium in mitigating these toxic effects. A total of 24 Sprague Dawley male adult rats were divided equally into four groups, as follows: control group, magnesium (Mg) group (50 mg/kg/d), SiNPs group (100 mg/kg/d), and SiNPs+ Mg group. Rats were treated with SiNPs by oral gavage for 90 days. The liver transaminases, serum creatinine, and cortisol levels were evaluated. The tissue malondialdehyde (MDA) and reduced glutathione (GSH) levels were measured. Additionally, the weight of the organs and the histopathological changes were examined. Our results demonstrated that SiNPs exposure caused increased weight in the kidneys and adrenal glands. Exposure to SiNPs was also associated with significant alterations in liver transaminases, serum creatinine, cortisol, MDA, and GSH. Additionally, histopathological changes were significantly reported in the liver, kidneys, and adrenal glands of SiNPs-treated rats. Notably, when we compared the control group with the treated groups with SiNPs and Mg, the results revealed that magnesium could mitigate SiNPs-induced biochemical and histopathologic changes, confirming its effective role as an antioxidant that reduced the accumulation of SiNPs in tissues, and that it returns the levels of liver transaminases, serum creatinine, cortisol, MDA, and GSH to almost normal values.

Toxicity evaluation of silica nanoparticles for delivery applications

Silica nanoparticles (SiNPs) are being explored as nanocarriers for therapeutics delivery, which can address a number of intrinsic drawbacks of therapeutics. To translate laboratory innovation into clinical application, their potential toxicity has been of great concern. This review attempts to comprehensively summarize the existing literature on the toxicity assessment of SiNPs. The current data suggest that the composition of SiNPs, their physicochemical properties, their administration route, their frequency and duration of administration, and the sex of animal models are related to their tissue and blood toxicity, immunotoxicity, and genotoxicity. However, the correlation between in vitro and in vivo toxicity has not been well established, mainly because both the in vitro and the in vivo-dosed quantities are unrealistic. This article also discusses important factors to consider in the toxicology of SiNPs and current approaches to reducing their toxicity. The aim is to give readers a better understanding of the toxicology of silica nanoparticles and to help identify key gaps in knowledge and techniques.

Gold Nanoparticles Reduce Food Sensation in Caenorhabditis elegans via the Voltage-Gated Channel EGL-19

Introduction

The increasing use of gold nanoparticles (Au NPs) in the medical field has raised concerns about the potential adverse effect of Au NPs exposure. However, it is difficult to assess the health risks of Au NPs exposure at the individual organ level using current measurement techniques.

Methods

The physical and chemical properties of Au NPs were characterized by transmission electron microscope (TEM), Fourier transform infrared (FTIR), and zeta sizer. The RNA-seq data of Au NPs-exposed worms were analyzed. The food intake was measured by liquid culture and Pharyngeal pumping rate. The function of the smell and taste neurons was evaluated by the chemotaxis and avoidance assay. The activation of ASE neurons was analyzed by calcium imaging. The gene expression of ins-22 and egl-19 was obtained from the C. elegans single cell RNA-seq databases.

Results

Our data analysis indicated that 62.8% of the significantly altered genes were functional in the nervous system. Notably, developmental stage analysis demonstrated that exposure to Au NPs interfered with animal development by regulating foraging behavior. Also, our chemotaxis results showed that exposure to Au NPs reduced the sensation of C. elegans to NaCl, which was consistent with the decrease in calcium transit of ASEL. Further studies confirmed that the reduced calcium transit was dependent on voltage-gated calcium channel EGL-19. The neuropeptide INS-22 was partially involved in Au NPs-induced NaCl sensation defect. Therefore, we proposed that Au NPs reduced the calcium transit in the ASEL neuron through egl-19-dependent calcium channels. It was partially regulated by the DAF-16 targeting neuropeptide INS-22.

Discussion

Our results demonstrate that Au NPs affect food sensation by reducing the calcium transit in ASEL neurons, which further leads to reduced pharynx pumping and feeding defects. The toxicology studies of Au NPs from worms have great potential to guide the usage of Au NPs in the medical field such as targeted drug delivery.

Structural parameters of nanoparticles affecting their toxicity for biomedical applications: a review

Rapidly growing interest in using nanoparticles (NPs) for biomedical applications has increased concerns about their safety and toxicity. In comparison with bulk materials, NPs are more chemically active and toxic due to the greater surface area and small size. Understanding the NPs' mechanism of toxicity, together with the factors influencing their behavior in biological environments, can help researchers to design NPs with reduced side effects and improved performance. After overviewing the classification and properties of NPs, this review article discusses their biomedical applications in molecular imaging and cell therapy, gene transfer, tissue engineering, targeted drug delivery, Anti-SARS-CoV-2 vaccines, cancer treatment, wound healing, and anti-bacterial applications. There are different mechanisms of toxicity of NPs, and their toxicity and behaviors depend on various factors, which are elaborated on in this article. More specifically, the mechanism of toxicity and their interactions with living components are discussed by considering the impact of different physiochemical parameters such as size, shape, structure, agglomeration state, surface charge, wettability, dose, and substance type. The toxicity of polymeric, silica-based, carbon-based, and metallic-based NPs (including plasmonic alloy NPs) have been considered separately.

Versatile nanodiamond-based tools for therapeutics and bioimaging

Nanodiamonds (NDs) are a remarkable class of carbon-based nanoparticles in nanomedicine which have recently become a hot topic of research due to their unique features including functionalization versatility, tunable opto-magnetic properties, chemical stability, minimal cytotoxicity, high affinity to biomolecules and biocompatibility. These attractive features make NDs versatile tools for a wide range of biologically relevant applications. In this feature article, we discuss the opto-magnetic properties of negatively charged nitrogen vacancy (NV^-) centres in NDs as fluorescence probes. We further discuss the frequently used chemical methods for surface chemistry modification of NDs which are relevant for biomedical applications. The in vitro and in vivo biocompatibility of modified NDs is also highlighted. Subsequently, we give an overview of recent state-of-the-art biomedical applications of NDs as versatile tools for bioimaging and detection, and as targeting nanocarriers for chemotherapy, photodynamic therapy, gene therapy, antimicrobial and antiviral therapy, and bone tissue engineering. Finally, we pinpoint the main challenges for NDs in biomedical applications which lie ahead and discuss perspectives on future directions in advancing the field for practical applications and clinical translations.

Nanoparticles and phototherapy combination as therapeutic alternative in prostate cancer: A scoping review

Prostate cancer (CaP) is one of the most common types of cancers worldwide. Despite the existing surgical techniques, prostatectomy patients may experience tumor recurrence. In addition, castration-resistant cancers pose a challenge, especially given their lack of response to standard care. Thus, the development of more efficient therapies has become a field of great interest, and photothermal therapy (PTT) and photodynamic therapy (PDT) are promising alternatives, given their high capacity to cause cell injury and consequent tumor ablation. Phototherapy, along with chemotherapy, has also been shown to be more effective than pharmacotherapy alone. Free molecules used as photosensitizers are rapidly cleared from the body, do not accumulate in the tumor, and are primarily hydrophobic and require toxic solvents. Thus, the use of nanoparticles can be an effective strategy, given their ability to carry or bind to different molecules, protecting them from degradation and allowing their association with other surface ligands, which favors permeation and retention at the tumor site. Despite this, there is still a gap in the literature regarding the use of phototherapy in association with nanotechnology for the treatment of CaP. In this scoping review, it was found that most of the particles studied could act synergistically through PDT and PTT. In addition, fluorescent quenchers can act as diagnostic and therapeutic tools. However, future clinical studies should be performed to confirm the benefits and safety of the combination of nanoparticles and phototherapy for CaP.

Ameliorative Effects of some Natural Antioxidants against Blood and Cardiovascular Toxicity of Oral Subchronic Exposure to Silicon Dioxide, Aluminum Oxide, or Zinc Oxide Nanoparticles in Wistar Rats

The present study determines the possible protective role of fig fruit extract with olive oil and date palm fruit extract (FOD) in decreasing the oral subchronic blood and cardiovascular toxicity of SiO₂NPs, Al₂O₃NPs, or ZnONPs. The present study used 80 male Wistar rats (8 groups, n = 10) distributed according to the treatment. The FOD treatments were used at their recommended antioxidant doses. All nanoparticles (NPs) were given orally and daily at doses of 100 mg/kg for 75 days. The oral administration of different NPs alone led to dramatic, oxidative stress, inflammatory markers, blood coagulation, endothelial dysfunction markers, myocardial enzymes, hematological parameters, lipid profile, and histopathological features compared with the control group. The FOD-NP-treated groups recorded significantly ameliorated blood and cardiovascular toxicity hazards compared to the groups administered with the NPs alone. In conclusion, the administration of FOD provides considerable chemopreventive and ameliorative effects against NP toxicity.

Ultrasmall silica nanoparticles in translational biomedical research: Overview and outlook

The exemplary progress of silica nanotechnology has attracted extensive attention across a range of biomedical applications such as diagnostics and imaging, drug delivery, and therapy of cancer and other diseases. Ultrasmall silica nanoparticles (USNs) have emerged as a particularly promising class demonstrating unique properties that are especially suitable for and have shown great promise in translational and clinical biomedical research. In this review, we discuss synthetic strategies that allow precise engineering of USNs with excellent control over size and surface chemistry, functionalization, and pharmacokinetic and toxicological profiles. We summarize the current state-of-the-art in the biomedical applications of USNs with a particular focus on select clinical studies. Finally, we illustrate long-standing challenges in the translation of inorganic nanotechnology, particularly in the context of ultrasmall nanomedicines, and provide our perspectives on potential solutions and future opportunities in accelerating the translation and widespread adoption of USN technology in biomedical research.

Cytotoxic effects of crystalline silica in form of micro and nanoparticles on the human lung cell line A549

Airborne crystalline silica (SiO₂) particles are one of the most common pollutants in stone industries. Limited studies have investigated the health effects of crystalline SiO₂ nanoparticles. Hence, the objective of this study was to study the cytotoxicity of SiO₂ in nano and micron sizes. A mineral quartz sample in the range of 0.2-0.8 mm sizes was purchased. These particles were ground at about 5 and 0.1 microns. Human cell line A549 was exposed to micro and nanometer particles at concentrations of 10, 50, 100, and 250 μg/ml for 24 and 72 h. Subsequently, the cytotoxicity of exposed cells was investigated by measuring cell survival, ROS generation, mitochondrial permeability, and intracellular glutathione content. The results showed that crystalline SiO₂ nano and microparticles decreased cell survival, increased ROS generation, damaged the mitochondrial membrane, and lowered the antioxidant content of these cells in a concentration- and time-dependent manner. The toxicity of crystalline SiO₂ microparticles at concentrations ≤50 μg/mL was greater than for nanoparticles, which was the opposite at concentrations ≥100 μg/mL. Exposure time and concentration were crucial factors for the cytotoxicity of exposed A549 cells to crystalline SiO₂ particles, which can affect the severity of the effect of particle size. Due to the limitation of exposure concentration and test durations in this study, further studies on the parameters of nanoparticle toxicity and underlying mechanisms could advance our knowledge.

Cell surface biotinylation to identify the receptors involved in nanoparticle uptake into endothelial cells

Targeted drug delivery requires -among others- specific interaction of nanocarriers with cell surface receptors enabling efficient internalization into the targeted cells. Thus, identification of receptors allowing efficient nanocarrier uptake is essential to improve the design of targeted nanomedicines. Here we used methods based on cell surface biotinylation to identify cell surface receptors mediating nanoparticle uptake by cells. We used human brain and liver endothelial cells as representative examples of cells typically showing very low and very high nanoparticle uptake, respectively. Amino-modified and carboxylated silica were used as model nanoparticles usually associated with high and low uptake into cells, respectively, and carrying different coronas after exposure in full human plasma. Using cell surface biotinylation of live cells and receptor pull-down assays, we compared the receptors internalized in control untreated cells and those internalized upon exposure to nanoparticles. In this way, we identified receptors associated with (high) nanoparticle uptake. The candidate receptors were further validated by decorating the nanoparticles with an artificial corona consisting of the respective receptor ligands. We found that a vitronectin corona can be used to target integrin receptors and strongly enhances nanoparticle uptake in brain and liver endothelial cells. The increased uptake was maintained in the presence of serum, suggesting that the vitronectin-corona could resist interaction and competition with serum. Furthermore, plasminogen-coated nanoparticles promoted uptake in endothelial cells of the liver, but not of the brain. The presented approach using reversible biotinylation of cell surface receptors in live cells allows for receptor-based targeting of nanocarriers that are instrumental in nanoparticle uptake, which can be exploited for targeted drug delivery. STATEMENT OF SIGNIFICANCE: In order to deliver drugs to their site of action, drug-loaded nanocarriers can be targeted to cell receptors enabling efficient uptake into target cells. Thus, methods to identify nanocarrier receptors are invaluable. Here we used reversible biotinylation of live cells and receptor pull-down approaches for receptor identification. By comparative analysis of the individual receptors internalized in untreated cells and cells exposed to nanoparticles, we identified receptors enabling high nanoparticle uptake into liver and brain endothelial cells. Their role was confirmed by decorating nanoparticles with an artificial corona composed of the receptor ligands. In conclusion, live cell reversible biotinylation of cell surface proteins is a powerful tool for the identification of potential receptors for receptor-based targeting of nanocarriers.

Chiral-engineered supraparticles: Emerging tools for drug delivery

The handedness of chiral-engineered supraparticles (CE-SPs) influences their interactions with cells and proteins, as evidenced by the increased penetration of breast, cervical, and myeloma cell membranes by d-chirality-coordinated SPs. Quartz crystal dissipation and isothermal titration calorimetry have been used to investigate such chiral-specific interactions. d-SPs are more thermodynamically stable compared with l-SPs in terms of their adhesion. Proteases and other endogenous proteins can be shielded by the opposite chirality of d-SPs, resulting in longer half-lives. Incorporating nanosystems with d-chirality increases uptake by cancer cells and prolongs in vivo stability, demonstrating the importance of chirality in biomaterials. Thus, as we discuss here, chiral nanosystems could enhance drug delivery systems, tumor markers, and biosensors, among other biomaterial-based technologies, by allowing for better control over their features.

Silica-Based Nanomaterials for Diabetes Mellitus Treatment

Diabetes mellitus, a chronic metabolic disease with an alarming global prevalence, is associated with several serious health threats, including cardiovascular diseases. Current diabetes treatments have several limitations and disadvantages, creating the need for new effective formulations to combat this disease and its associated complications. This motivated the development of therapeutic strategies to overcome some of these limitations, such as low therapeutic drug bioavailability or poor compliance of patients with current therapeutic methodologies. Taking advantage of silica nanoparticle characteristics such as tuneable particle and pore size, surface chemistry and biocompatibility, silica-based nanocarriers have been developed with the potential to treat diabetes and regulate blood glucose concentration. This review discusses the main topics in the field, such as oral administration of insulin, glucose-responsive devices and innovative administration routes.

The Study of Nanosized Silicate-Substituted Hydroxyapatites Co-Doped with Sr2+ and Zn2+ Ions Related to Their Influence on Biological Activities

Nanosized silicate-substituted hydroxyapatites, characterized by the general formula Ca_9.8-x-nSr_nZn_x(PO₄)_6-y(SiO₄)_y(OH)₂ (where: n = 0.2 [mol%]; x = 0.5-3.5 [mol%]; y = 4-5 [mol%]), co-doped with Zn²⁺ and Sr²⁺ ions, were synthesized with the help of a microwave-assisted hydrothermal technique. The structural properties were determined using XRD (X-ray powder diffraction) and Fourier-transformed infrared spectroscopy (FT-IR). The morphology, size and shape of biomaterials were detected using scanning electron microscopy techniques (SEM). The reference strains of Klebsiella pneumoniae, Escherichia coli and Pseudomonas aeruginosa were used to assess bacterial survivability and the impact on biofilm formation in the presence of nanosilicate-substituted strontium-hydroxyapatites. Safety evaluation was also performed using the standard cytotoxicity test (MTT) and hemolysis assay. Moreover, the mutagenic potential of the materials was assessed (Ames test). The obtained results suggest the dose-dependent antibacterial activity of nanomaterials, especially observed for samples doped with 3.5 mol% Zn²⁺ ions. Moreover, the modification with five SiO₄ groups enhanced the antibacterial effect; however, a rise in the toxicity was observed as well. No harmful activity was detected in the hemolysis assay as well as in the mutagenic assay (Ames test).

From Synthetic Route of Silica Nanoparticles to Theranostic Applications

The advancements in nanotechnology have quickly developed a new subject with vast applications of nanostructured materials in medicine and pharmaceuticals. The enormous surface-to-volume ratio, ease of surface modification, outstanding biocompatibility, and, in the case of mesoporous nanoparticles, the tunable pore size make the silica nanoparticles (SNPs) a promising candidate for nano-based medical applications. The preparation of SNPs and their contemporary usage as drug carriers, contrast agents for imaging, carrier of photosensitizers (PS) in photodynamic, as well as photothermal treatments are intensely discussed in this review. Furthermore, the potential harmful responses of silica nanoparticles are reviewed using data obtained from in vitro and in vivo experiments conducted by several studies. Moreover, we showcase the engineering of SNPs for the theranostic applications that can address several intrinsic limitations of conventional therapeutics and diagnostics. In the end, a personal perspective was outlined to state SNPs’ current status and future directions, focusing on SNPs’ significant potentiality and opportunities.

Fluorescent silica nanoparticles as an internal marker in fruit flies and their effects on survivorship and fertility

Tracking and differentiating small insects at the individual levels requires appropriate marking materials because of their small size. This study proposes and investigates the use of fluorescent silica nanoparticles (FSNPs) as an internal marker owing to their good optical properties and biocompatibility. FSNPs were prepared using the water-in-oil reverse microemulsion technique with Rubpy dye as a fluorophore. The obtained particles were spherical, monodispersed in nanosize and exhibited bright orange luminescence under ultraviolet (UV) light. Internal marking was accomplished in fruit flies (Drosophila melanogaster) through feeding. The result shows that the fruit flies exhibit bright luminescence in their abdomen when exposed to UV light. The marking persistence duration of FSNPs in the fruit fly bodies is longer than those of other fluorescent dyes. Fruit flies fed with FSNPs have a longer lifespan than those fed with Rubpy dye. There was no difference in fertility and negative geotaxis response among the treatment and control groups. These findings demonstrate that FSNPs can be used as an internal marker in fruit flies, and are possibly applied with other small insects with a translucent abdomen.

Biocompatibility and Connectivity of Semiconductor Nanostructures for Cardiac Tissue Engineering Applications

Nano- or microdevices, enabling simultaneous, long-term, multisite, cellular recording and stimulation from many excitable cells, are expected to make a strategic turn in basic and applied cardiology (particularly tissue engineering) and neuroscience. We propose an innovative approach aiming to elicit bioelectrical information from the cell membrane using an integrated circuit (IC) bearing a coating of nanowires on the chip surface. Nanowires grow directly on the backend of the ICs, thus allowing on-site amplification of bioelectric signals with uniform and controlled morphology and growth of the NWs on templates. To implement this technology, we evaluated the biocompatibility of silicon and zinc oxide nanowires (NWs), used as a seeding substrate for cells in culture, on two different primary cell lines. Human cardiac stromal cells were used to evaluate the effects of ZnO NWs of different lengths on cell behavior, morphology and growth, while BV-2 microglial-like cells and GH4-C1 neuroendocrine-like cell lines were used to evaluate cell membrane–NW interaction and contact when cultured on Si NWs. As the optimization of the contact between integrated microelectronics circuits and cellular membranes represents a long-standing issue, our technological approach may lay the basis for a new era of devices exploiting the microelectronics’ sensitivity and “smartness” to both improve investigation of biological systems and to develop suitable NW-based systems available for tissue engineering and regenerative medicine.

Luminescence Nanomaterials for Biosensing Applications

Due to their capabilities of immobilizing more bioreceptor parts with reduced volumes, nanomaterials have emerged as potential tools for increasing sensitivity to specific molecules. Furthermore, carbon nanotube, gold nanoparticles, polymer nanoparticles, semiconductor quantum dots, graphene, nano-diamonds and graphene are among the nanomaterials that are under investigation. Due to the fast development of such a field of research, review summarises the classification of biosensors using main receptors, and designing biosensors. Numerous studies have concentrated on the manipulation of Persistent luminescence nanoparticles (PLNPs) in biosensing, cell tracking, bioimaging, and cancer therapy due to the effective removal of the autofluorescence interferences from tissues and the ultra-long near-infrared afterglow emission. As luminescence has a unique optical property, it can be detected without constant external illumination, preventing autofluorescence and light dispersion through tissues. These successes sparked an increasing curiosity in creating novel PLNP kinds with desired superior properties and multiple purposes. In this review, we emphasize the most recent developments in biosensing, imaging, and image-guided therapy while summarizing the research on synthesis methods, bio applications, bio membrane modification and bio-safety of PLNPs. Finally, the remaining issues and difficulties are examined together with prospective future developments in the field of biomedical applications.

A toxicological profile of silica nanoparticles

Humans are regularly exposed to silica nanoparticles in environmental and occupational contexts, and these exposures have been implicated in the onset of adverse health effects. Existing reviews on silica nanoparticle toxicity are few and not comprehensive. There are natural and synthetic sources by which crystalline and amorphous silica nanoparticles are produced. These processes influence physiochemical properties, which are factors that can dictate toxicological effects. Toxicological assessment includes exposure scenario (e.g. environmental, occupational), route of exposure, toxicokinetics, and toxicodynamics. Broader considerations include pathology, risk assessment, regulation, and treatment after injury. This review aims to consolidate the most relevant and up-to-date research in these areas to provide an exhaustive toxicological profile of silica nanoparticles.

Comprehensive Review on the Degradation Chemistry and Toxicity Studies of Functional Materials

In recent decades there has been growing interest of material chemists in the successful development of functional materials for drug delivery, tissue engineering, imaging, diagnosis, theranostic, and other biomedical applications with advanced nanotechnology tools. The efficacy and safety of functional materials are determined by their pharmacological, toxicological, and immunogenic effects. It is essential to consider all degradation pathways of functional materials and to assess plausible intermediates and final products for quality control. This review provides a brief insight into chemical degradation mechanisms of functional materials like oxidation, photodegradation, and physical and enzymatic degradation. The intermediates and products of degradation were confirmed with analytical methods such as proton nuclear magnetic resonance (¹H NMR), gel permeation chromatography (GPC), UV-vis spectroscopy (UV-vis), infrared spectroscopy (IR), differential scanning calorimetry (DSC), mass spectroscopy, and other sophisticated analytical methods. These analytical methods are also used for regulatory, quality control, and stability purposes in industry. The assessment of degradation is important to predetermine the behavior of functional materials in specific storage conditions and can be relevant to their behavior during in vivo applications. Another important aspect is the evaluation of the toxicity of functional materials. Toxicity can be accessed with various methods using in vitro, in vivo, ex vivo, and in silico models. In vitro cell culture methods are used to determine mitochondrial damage, reactive oxygen species, stress responses, and cellular toxicity. In vitro cellular toxicity can be measured by MTT assay, LDH leakage assay, and hemolysis. In vivo studies are performed using various animal models involving zebrafish, rodents (mice and rats), and nonhuman primates. Ex vivo studies are also used for efficacy and toxicity determinations of functional materials like ex vivo potency assay and precision-cut liver slice (PCLS) models. The in silico tools with computational simulations like quantitative structure-activity relationships (QSAR), pharmacokinetics (PK) and pharmacodynamics (PD), dose and time response, and quantitative cationic-activity relationships ((Q)CARs) are used for prediction of the toxicity of functional materials. In this review, we studied the principle methods used for degradation studies, different degradation pathways, and mechanisms of functional material degradation with prototype examples. We discuss toxicity assessments with different toxicity approaches used for estimation of the safety and efficacy of functional materials.

Heterogeneous Rate Constant for Amorphous Silica Nanoparticle Adsorption on Phospholipid Monolayers

The interaction of amorphous silica nanoparticles with phospholipid monolayers and bilayers has received a great deal of interest in recent years and is of importance for assessing potential cellular toxicity of such species, whether natural or synthesized for the purpose of nanomedical drug delivery and other applications. This present communication studies the rate of silica nanoparticle adsorption on to phospholipid monolayers in order to extract a heterogeneous rate constant from the data. This rate constant relates to the initial rate of growth of an adsorbed layer of nanoparticles as SiO₂ on a unit area of the monolayer surface from unit concentration in dispersion. Experiments were carried out using the system of dioleoyl phosphatidylcholine (DOPC) monolayers deposited on Pt/Hg electrodes in a flow cell. Additional studies were carried out on the interaction of soluble silica with these layers. Results show that the rate constant is effectively constant with respect to silica nanoparticle size. This is interpreted as indicating that the interaction of hydrated SiO₂ molecular species with phospholipid polar groups is the molecular initiating event (MIE) defined as the initial interaction of the silica particle surface with the phospholipid layer surface promoting the adsorption of silica nanoparticles on DOPC. The conclusion is consistent with the observed significant interaction of soluble SiO₂ with the DOPC layer and the established properties of the silica-water interface.

Ultrasmall iron oxide nanoparticles cause significant toxicity by specifically inducing acute oxidative stress to multiple organs

Background

Iron oxide nanoparticles have been approved by food and drug administration for clinical application as magnetic resonance imaging (MRI) and are considered to be a biocompatible material. Large iron oxide nanoparticles are usually used as transversal (T₂) contrast agents to exhibit dark contrast in MRI. In contrast, ultrasmall iron oxide nanoparticles (USPIONs) (several nanometers) showed remarkable advantage in longitudinal (T₁)-weighted MRI due to the brighten effect. The study of the toxicity mainly focuses on particles with size of tens to hundreds of nanometers, while little is known about the toxicity of USPIONs.

Results

We fabricated Fe₃O₄ nanoparticles with diameters of 2.3, 4.2, and 9.3 nm and evaluated their toxicity in mice by intravenous injection. The results indicate that ultrasmall iron oxide nanoparticles with small size (2.3 and 4.2 nm) were highly toxic and were lethal at a dosage of 100 mg/kg. In contrast, no obvious toxicity was observed for iron oxide nanoparticles with size of 9.3 nm. The toxicity of small nanoparticles (2.3 and 4.2 nm) could be reduced when the total dose was split into 4 doses with each interval for 5 min. To study the toxicology, we synthesized different-sized SiO₂ and gold nanoparticles. No significant toxicity was observed for ultrasmall SiO₂ and gold nanoparticles in the mice. Hence, the toxicity of the ultrasmall Fe₃O₄ nanoparticles should be attributed to both the iron element and size. In the in vitro experiments, all the ultrasmall nanoparticles (< 5 nm) of Fe₃O₄, SiO₂, and gold induced the generation of the reactive oxygen species (ROS) efficiently, while no obvious ROS was observed in larger nanoparticles groups. However, the ·OH was only detected in Fe₃O₄ group instead of SiO₂ and gold groups. After intravenous injection, significantly elevated ·OH level was observed in heart, serum, and multiple organs. Among these organs, heart showed highest ·OH level due to the high distribution of ultrasmall Fe₃O₄ nanoparticles, leading to the acute cardiac failure and death.

Conclusion

Ultrasmall Fe₃O₄ nanoparticles (2.3 and 4.2 nm) showed high toxicity in vivo due to the distinctive capability in inducing the generation of ·OH in multiple organs, especially in heart. The toxicity was related to both the iron element and size. These findings provide novel insight into the toxicology of ultrasmall Fe₃O₄ nanoparticles, and also highlight the need of comprehensive evaluation for their clinic application.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00465-y.

Mesoporous Silica-Coated Gold Nanoparticles for Multimodal Imaging and Reactive Oxygen Species Sensing of Stem Cells

Stem cell (SC)-based therapies hold the potential to revolutionize therapeutics by enhancing the body's natural repair processes. Currently, there are only three SC therapies with marketing authorization within the European Union. To optimize outcomes, it is important to understand the biodistribution and behavior of transplanted SCs in vivo. A variety of imaging agents have been developed to trace SCs; however, they mostly lack the ability to simultaneously monitor the SC function and biodistribution at high resolutions. Here, we report the synthesis and application of a nanoparticle (NP) construct consisting of a gold NP core coated with rhodamine B isothiocyanate (RITC)-doped mesoporous silica (AuMS). The MS layer further contained a thiol-modified internal surface and an amine-modified external surface for dye conjugation. Highly fluorescent AuMS of three different sizes were successfully synthesized. The NPs were non-toxic and efficiently taken up by limbal epithelial SCs (LESCs). We further showed that we can functionalize AuMS with a reactive oxygen species (ROS)-sensitive fluorescent dye using two methods, loading the probe into the mesopores, with or without additional capping by a lipid bilayer, and by covalent attachment to surface and/or mesoporous-functionalized thiol groups. All four formulations displayed a ROS concentration-dependent increase in fluorescence. Further, in an ex vivo SC transplantation model, a combination of optical coherence tomography and fluorescence microscopy was used to synergistically identify AuMS-labeled LESC distribution at micrometer resolution. Our AuMS constructs allow for multimodal imaging and simultaneous ROS sensing of SCs and represent a promising tool for in vivo SC tracing.

Mechanistic study of silica nanoparticles on the size-dependent retinal toxicity in vitro and in vivo

Background

Silica nanoparticles (SiO₂ NPs) are extensively applied in the biomedical field. The increasing medical application of SiO₂ NPs has raised concerns about their safety. However, studies on SiO₂ NP-induced retinal toxicity are lacking.

Methods

We investigated the retinal toxicity of SiO₂ NPs with different sizes (15 and 50 nm) in vitro and in vivo along with the underlying mechanisms. The cytotoxicity of SiO₂ NPs with different sizes was assessed in R28 human retinal precursor cells by determining the ATP content and LDH release. The cell morphologies and nanoparticle distributions in the cells were analyzed by phase-contrast microscopy and transmission electron microscopy, respectively. The mitochondrial membrane potential was examined by confocal laser scanning microscopy. The retinal toxicity induced by SiO₂ NPs in vivo was examined by immunohistochemical analysis. To further investigate the mechanism of retinal toxicity induced by SiO₂ NPs, reactive oxygen species (ROS) generation, glial cell activation and inflammation were monitored.

Results

The 15-nm SiO₂ NPs were found to have higher cytotoxicity than the larger NPs. Notably, the 15-nm SiO₂ NPs induced retinal toxicity in vivo, as demonstrated by increased cell death in the retina, TUNEL-stained retinal cells, retinal ganglion cell degeneration, glial cell activation, and inflammation. In addition, The SiO₂ NPs caused oxidative stress, as demonstrated by the increase in the ROS indicator H₂DCF-DA. Furthermore, the pretreatment of R28 cells with N-acetylcysteine, an ROS scavenger, attenuated the ROS production and cytotoxicity induced by SiO₂ NPs.

Conclusions

These results provide evidence that SiO₂ NPs induce size-dependent retinal toxicity and suggest that glial cell activation and ROS generation contribute to this toxicity.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01326-8.

The Formulation, Development and Application of Oil Dispersants

Oil spills in open waters pose a significant threat to marine life. The application of dispersant as an oil-spill response is a promising approach to minimize the environmental burden caused by these accidental events. Dispersants have been accepted and applied by many countries around the world as a countermeasure in responding to oil spills due to their great success and advancements in recent years. This review covers different approaches for design and development of chemical formulas of oil dispersants with the aim to improve dispersing efficiencies, followed by formulating non-chemical dispersants, which are more environmentally friendly approaches. The encouraging properties motivate scientific communities to research and develop these non-chemical-based dispersants. In general, this review intends to offer a multi-perspective overall picture of progress made in recent years to develop and apply different dispersants suitable for combating oil spills.

Pickering foams and parameters influencing their characteristics

Pickering foams are available in many applications and have been continually gaining interest in the last two decades. Pickering foams are multifaceted, and their characteristics are highly dependent on many factors, such as particle size, charge, hydrophobicity and concentration as well as the charge and concentration of surfactants and salts available in the system. A literature review of these individual studies at first might seem confusing and somewhat contradictory, particularly in multi-component systems with particles and surfactants with different charges in the presence of salts. This paper provides a comprehensive overview of particle-stabilized foams, also known as Pickering foams and froths. Underlying mechanisms of foam stabilization by particles with different morphology, surface chemistry, size and type are reviewed and clarified. This paper also outlines the role of salts and different factors such as pH, temperature and gas type on Pickering foams. Further, we highlight recent developments in Pickering foams in different applications such as food, mining, oil and gas, and wastewater treatment industries, where Pickering foams are abundant. We conclude this overview by presenting important research avenues based on the gaps identified here. The focus of this review is limited to Pickering foams of surfactants with added salts and does not include studies on polymers, proteins, or other macromolecules.

High Doses of Silica Nanoparticles Obtained by Microemulsion and Green Routes Compromise Human Alveolar Cells Morphology and Stiffness Differently

Among all the inorganic nanomaterials used in commercial products, industry, and medicine, the amorphous silica nanoparticles (SiO2 NPs) appeared to be often tolerated in living organisms. However, despite several toxicity studies, some concerns about the exposure to high doses of SiO2 NPs with different sizes were raised. Then, we used the microemulsion method to obtain stable SiO2 NPs having different sizes (110 nm, 50 nm, and 25 nm). In addition, a new one-pot green synthetic route using leaves extract of Laurus nobilis was performed, obtaining monodispersed ultrasmall SiO2 NPs without the use of dangerous chemicals. The NPs achieved by microemulsion were further functionalized with amino groups making the NPs surface positively charged. Then, high doses of SiO2 NPs (1 mg/mL and 3 mg/mL) achieved from the two routes, having different sizes and surface charges, were used to assess their impact on human alveolar cells (A549), being the best cell model mimicking the inhalation route. Cell viability and caspase-3 induction were analyzed as well as the cellular uptake, obtaining that the smallest (25 nm) and positive-charged NPs were more able to induce cytotoxicity, reaching values of about 60% of cell death. Surprisingly, cells incubated with green SiO2 NPs did not show strong toxicity, and 70% of them remained vital. This result was unusual for ultrasmall nanoobjects, generally highly toxic. The actin reorganization, nuclear morphology alteration, and cell membrane elasticity analyses confirmed the trend achieved from the biological assays. The obtained data demonstrate that the increase in cellular softness, i.e., the decrease in Young’s modulus, could be associated with the smaller and positive NPs, recording values of about 3 kPa. On the contrary, green NPs triggered a slight decrease of stiffness values (c.a. 6 kPa) compared to the untreated cells (c.a. 8 kPa). As the softer cells were implicated in cancer progression and metastasization, this evidence strongly supported the idea of a link between the cell elasticity and physicochemical properties of NPs that, in turn, influenced the interaction with the cell membrane. Thus, the green SiO2 NPs compromised cells to a lesser extent than the other SiO2 NPs types. In this scenario, the elasticity evaluation could be an interesting tool to understand the toxicity of NPs with the aim of predicting some pathological phenomena associated with their exposure.

Applications and Biocompatibility of Mesoporous Silica Nanocarriers in the Field of Medicine

Mesoporous silica nanocarrier (MSN) preparations have a wide range of medical applications. Studying the biocompatibility of MSN is an important part of clinical transformation. Scientists have developed different types of mesoporous silica nanocarriers (MSNs) for different applications to realize the great potential of MSNs in the field of biomedicine, especially in tumor treatment. MSNs have achieved good results in diagnostic bioimaging, tissue engineering, cancer treatment, vaccine development, biomaterial application and diagnostics. MSNs can improve the therapeutic efficiency of drugs, introduce new drug delivery strategies, and provide advantages that traditional drugs lack. It is necessary not only to innovate MSNs but also to comprehensively understand their biological distribution. In this review, we summarize the various medical uses of MSN preparations and explore the factors that affect their distribution and biocompatibility in the body based on metabolism. Designing more reasonable therapeutic nanomedicine is an important task for the further development of the potential clinical applications of MSNs.

Magnetic Nanostructures: Rational Design and Fabrication Strategies toward Diverse Applications

In recent years, the continuous development of magnetic nanostructures (MNSs) has tremendously promoted both fundamental scientific research and technological applications. Different from the bulk magnet, the systematic engineering on MNSs has brought a great breakthrough in some emerging fields such as the construction of MNSs, the magnetism exploration of multidimensional MNSs, and their potential translational applications. In this review, we give a detailed description of the synthetic strategies of MNSs based on the fundamental features and application potential of MNSs and discuss the recent progress of MNSs in the fields of nanomedicines, advanced nanobiotechnology, catalysis, and electromagnetic wave adsorption (EMWA), aiming to provide guidance for fabrication strategies of MNSs toward diverse applications.

Verteporfin-Loaded Mesoporous Silica Nanoparticles' Topical Applications Inhibit Mouse Melanoma Lymphangiogenesis and Micrometastasis In Vivo

Photodynamic therapy (PDT) has been pointed out as a candidate for improving melanoma treatment. Nanotechnology application in PDT has increased its efficacy by reducing side effects. Herein, mesoporous silica nanoparticles (MSNs) conjugated with verteporfin (Ver-MSNs), in use with PDT, were administered in mice to evaluate their efficacy on lymphoangiogenesis and micrometastasis in melanoma. Melanoma was induced in mice by the subcutaneous injection of B16-F10 cells. The mice were transcutaneously treated with MSNs, Ver-MSNs, or glycerol and exposed to red light. The treatment was carried out four times until day 20. Lymphangiogenesis and micrometastasis were identified by the immunohistochemical method. Lymphoangiogenesis was halved by MSN treatment compared with the control animals, whereas the Ver-MSN treatment almost abolished it. A similar reduction was also observed in lung micrometastasis. PDT with topically administrated Ver-MSNs reduced melanoma lymphoangiogenesis and lung micrometastasis, as well as tumor mass and angiogenesis, and therefore their use could be an innovative and useful tool in melanoma clinical therapy.

Photothermally responsive Pickering emulsions stabilised by polydopamine nanobowls

Pickering emulsions with stimuli responsive properties have attracted mounting research attention owing to their potential for on-demand destabilisation of emulsions. However, a combination of biocompatibility and long-term stability are essential to efficiently apply such systems in biomedical applications, and this remains a significant challenge. To address current limitations, here we report the formation of photothermally responsive oil-in-water (o/w) Pickering emulsions fabricated using biocompatible stabilisers and showing prolonged stability. For the first time, we explore polydopamine (PDA) bowl-shaped mesoporous nanoparticles (PDA nanobowls) as a Pickering stabiliser without any surface modification or other stabiliser present. As-prepared PDA nanobowl-stabilised Pickering emulsions are shown to be pH responsive, and more significantly show high photothermal efficiency under near-infrared illumination due the incorporation of PDA into the system, which has remarkable photothermal response. These biocompatible, photothermally responsive o/w Pickering emulsion systems show potential in controlled drug release applications stimulated by NIR illumination.

Submicron silica particles have cytotoxicities on hepatocellular carcinoma, non-small cell lung cancer and breast cancer by unified regulating the XLOC_001659/miR-98-5p/MAP3K2-mediated pathway

The cytotoxicities of silica (SiO₂s) particles against cancers are still controversial. In this study, the purchased submicron silica particles (SM-SiO₂s) were identified by transmission electron microscopy and energy dispersive spectrometer, and it showed potent cytotoxicities on hepatocellular carcinoma (HCC), non-small cell lung cancer (NSCLC) and breast cancer (BC), which ranked the top in the incidence among the tumor types. Through the microarray assay on long noncoding RNAs (lncRNAs) from the SM-SiO₂s-treated HCC, NSCLC and BC cells, followed by Venn analysis, we found that a series of lncRNAs were significantly regulated by SM-SiO₂s, among of which XLOC_001659 was mostly decreased. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) assay confirmed that XLOC_001659 could be decreased in all the SM-SiO₂s-treated HCC, NSCLC and BC cells, coupled to inhibited cell proliferation. Further, XLOC_001659 was recognized as a miR-98-5p sponge and therefore modulates the "pro-inflammatory tumor promoter" MAP3K2 expressions. The XLOC_001659/miR-98-5p/MAP3K2 axis uniformly mediated the regulation of SM-SiO₂s on proliferation of HCC, NSCLC and BC cells. Further clinical experiments demonstrated that XLOC_001659 was negatively correlated with miR-98-5p level and positively correlated with MAP3K2 level, and XLOC_001659/miR-98-5p/MAP3K2 axis was significantly associated with progressions and prognosis in HCC, NSCLC and BC patients. These results provide a new clue for the anti-tumor mechanism of SM-SiO₂s and a new way for drug development by using SM-SiO2s.

Effects of Nonporous Silica Nanoparticles on Human Trabecular Meshwork Cells

PRECIS

Silica nanoparticles (SiNPs), which are potential drug carriers for glaucoma treatment, may induce mild dose-dependent cytotoxicity but not so severe as to compromise a mammalian target of rapamycin (mTOR) pathway in immortalized trabecular meshwork (TM) cells.

PURPOSE

Nanoparticle-based ophthalmic drug delivery is a promising field of drug development. In this study, we evaluated the effect of nonporous SiNPs on human TM cells.

METHODS

TM cells were exposed to different concentrations (0 to 100 µg/mL) of SiNPs (50, 100, and 150 nm) for up to 48 hours. Transmission electron microscopy confirmed the intracellular distribution of SiNPs. Cellular viability assay, reactive oxygen species generation, autophagy, and activation of the mTOR pathway were evaluated. Histologic analysis of the TM structure was performed after intracameral injection of SiNPs (0.05 mL of 200 µg/mL concentration) in rabbits.

RESULTS

SiNPs were taken up by TM cells and localized in the cytoplasm. Neither nuclear entry nor mitochondrial damage was observed. SiNPs induced a mild but dose-dependent increase of lactate dehydrogenase. However, neither increase of intracellular reactive oxygen species levels nor apoptosis was observed after SiNPs exposure. Significant coactivation of autophagy and the mTOR pathway were observed with exposure to SiNPs. Aqueous plexus structure was well maintained without inflammation in rabbits after SiNPs exposure.

CONCLUSIONS

SiNPs induce mild and dose-dependent cytotoxicity in TM cells. However, the toxicity level is not enough to compromise the mTOR pathway of TM cells and histologic structure of the aqueous plexus tissue.

Characterization and Cytotoxicity Comparison of Silver- and Silica-Based Nanostructures

Core-shell structures are the most common type of composite material nanostructures due to their multifunctional properties. Silver nanoparticles show broad antimicrobial activity, but the safety of their utilization still remains an issue to tackle. In many applications, the silver core is coated with inorganic shell to reduce the metal toxicity. This article presents the synthesis of various materials based on silver and silica nanoparticles, including SiO2@Ag, Ag@SiO2, and sandwich nanostructures-Ag@SiO2@Ag-and the morphology of these nanomaterials based on transmission electron microscopy (TEM), UV-Vis spectroscopy, and FT-IR spectroscopy. Moreover, we conducted the angle measurements due to the strong relationship between the level of surface wettability and cell adhesion efficiency. The main aim of the study was to determine the cytotoxicity of the obtained materials against two types of human skin cells-keratinocytes (HaCaT) and fibroblasts (HDF). We found that among all the obtained structures, SiO2@Ag and Ag@SiO2 showed the lowest cell toxicity and very high half-maximal inhibitory concentration. Moreover, the measurements of the contact angle showed that Ag@SiO2 nanostructures were different from other materials due to their superhydrophilic nature. The novel approach presented here shows the promise of implementing core-shell type nanomaterials in skin-applied cosmetic or medical products.

Size-Dependent Cytotoxicity and Reactive Oxygen Species of Cerium Oxide Nanoparticles in Human Retinal Pigment Epithelia Cells

Purpose

The use of cerium oxide nanoparticles (CeO₂ NPs), a lanthanide element oxide and bivalent compound, has been growing continuously in industry and biomedicine. Due to their wide application, the potential human health problems of CeO₂ NPs have attracted attention, but studies on the toxicity of this compound to human eyes are lacking. This study investigated the cytotoxicity and reactive oxygen species (ROS) of CeO₂ NPs in human retinal pigment epithelial cells (ARPE-19 cells).

Methods

Using the transmission electron microscope (TEM), the size distribution and shape of CeO₂ NPs were characterized. To explore the effect of CeO₂ NP size on ophthalmic toxicity in vitro, three sizes (15, 30 and 45 nm) of CeO₂ NPs were investigated using ATP content measurement, LDH release measurement and cell proliferation assay in ARPE-19 cells. ROS values and mitochondrial membrane potential depolarization were evaluated by H₂DCF-DA staining and JC-1 staining. Morphology changes were detected using a phase-contrast microscope.

Results

The cytotoxicity of 15 nm CeO₂ NPs was found to be the highest and hence was further explored. Treatment with 15 nm CeO₂ NPs caused the morphology of ARPE-19 cells to change in a dose- and time-dependent manner. Moreover, the treatment induced excessive ROS generation and mitochondrial membrane potential depolarization. In addition, cytotoxicity was attenuated by the application of a ROS scavenger N-acetyl-L- cysteine (NAC).

Conclusion

CeO₂ NPs induced cytotoxicity in ARPE-19 cells and excessive production of ROS and decreasing mitochondrial membrane potential. The Overproduction of ROS partially contributes to CeO₂ NP-induced cytotoxicity.

Chemically induced hypoxia by dimethyloxalylglycine (DMOG)-loaded nanoporous silica nanoparticles supports endothelial tube formation by sustained VEGF release from adipose tissue-derived stem cells

Inadequate vascularization leading to insufficient oxygen and nutrient supply in deeper layers of bioartificial tissues remains a limitation in current tissue engineering approaches to which pre-vascularization offers a promising solution. Hypoxia triggering pre-vascularization by enhanced vascular endothelial growth factor (VEGF) expression can be induced chemically by dimethyloxalylglycine (DMOG). Nanoporous silica nanoparticles (NPSNPs, or mesoporous silica nanoparticles, MSNs) enable sustained delivery of molecules and potentially release DMOG allowing a durable capillarization of a construct. Here we evaluated the effects of soluble DMOG and DMOG-loaded NPSNPs on VEGF secretion of adipose tissue-derived stem cells (ASC) and on tube formation by human umbilical vein endothelial cells (HUVEC)-ASC co-cultures. Repeated doses of 100 µM and 500 µM soluble DMOG on ASC resulted in 3- to 7-fold increased VEGF levels on day 9 (P < 0.0001). Same doses of DMOG-NPSNPs enhanced VEGF secretion 7.7-fold (P < 0.0001) which could be maintained until day 12 with 500 µM DMOG-NPSNPs. In fibrin-based tube formation assays, 100 µM DMOG-NPSNPs had inhibitory effects whereas 50 µM significantly increased tube length, area and number of junctions transiently for 4 days. Thus, DMOG-NPSNPs supported endothelial tube formation by upregulated VEGF secretion from ASC and thus display a promising tool for pre-vascularization of tissue-engineered constructs. Further studies will evaluate their effect in hydrogels under perfusion.

Comprehensive review on ultrasound-responsive theranostic nanomaterials: mechanisms, structures and medical applications

The field of theranostics has been rapidly growing in recent years and nanotechnology has played a major role in this growth. Nanomaterials can be constructed to respond to a variety of different stimuli which can be internal (enzyme activity, redox potential, pH changes, temperature changes) or external (light, heat, magnetic fields, ultrasound). Theranostic nanomaterials can respond by producing an imaging signal and/or a therapeutic effect, which frequently involves cell death. Since ultrasound (US) is already well established as a clinical imaging modality, it is attractive to combine it with rationally designed nanoparticles for theranostics. The mechanisms of US interactions include cavitation microbubbles (MBs), acoustic droplet vaporization, acoustic radiation force, localized thermal effects, reactive oxygen species generation, sonoluminescence, and sonoporation. These effects can result in the release of encapsulated drugs or genes at the site of interest as well as cell death and considerable image enhancement. The present review discusses US-responsive theranostic nanomaterials under the following categories: MBs, micelles, liposomes (conventional and echogenic), niosomes, nanoemulsions, polymeric nanoparticles, chitosan nanocapsules, dendrimers, hydrogels, nanogels, gold nanoparticles, titania nanostructures, carbon nanostructures, mesoporous silica nanoparticles, fuel-free nano/micromotors.

Fecal microbiota transplantation attenuates nano-plastics induced toxicity in Caenorhabditis elegans

Current studies simply focus on the toxicity of nano-plastics, while the correlation between their toxicity and bio-distribution, as well as intestinal microorganisms is still blank. Therefore, we systematically evaluated the toxicity based on the accumulation characteristics of nano-plastics in C. elegans. Meanwhile, for the first time, human fecal microbiota was transplanted into the gut of C. elegans and found that nano-plastics can through the intestinal barrier to the whole body after oral intake and can't be drastically excreted until die, thus causing toxic effects; while human fecal microbiota transplantation can significantly improve the living state via activating PMK-1/SKN-1 pathway to promote the production of intracellular glutathione, and exogenous glutathione addition can also markedly protect nematodes against nano-plastics induced toxicity. Our results not only provide a fully understand between the accumulation characteristic and health risk of nano-plastics, but also take C. elegans and intestinal flora into the field of toxicity evolution of nanomaterials.