Silica-based nanoparticles for biomedical applications

Formation of intraneuronal iron deposits following local release from nanostructured silica injected into rat brain parenchyma

Nanostructured materials with controllable properties have been used to cage and release various types of compounds. In the present study, iron-loaded nanostructured sol-gel SiO2-Fe materials were prepared and injected into the rat brain to develop a method for gradual iron delivery into the neurons with the aims to avoid acute iron toxicity and develop an animal model of gradual, metal-induced neurodegeneration. Nanoparticles were prepared by the traditional method of hydrolysis and condensation reactions of tetraethyl orthosilicate at room temperature and subsequent heat treatment at 200 °C. FeSO4 was added in situ during the silica preparation. The resulting materials were characterized by UV-VIS and infrared spectroscopies, X-ray diffraction, and N2 adsorption-desorption. An in vitro ferrous sulfate release test was carried out in artificial cerebrospinal fluid as the release medium showing successful ferrous sulfate loading on nanostructured silica and sustained iron release during the test time of 10 h. Male Wistar rats administered with SiO2-Fe nanoparticles in the substantia nigra pars compacta (SNpc) showed significant intraneuronal increase of iron, in contrast to the animals administered with FeSO4 that showed severe neuronal loss, 72 h post-treatment. Both treatments induced lipid fluorescent product formation in the ventral midbrain, in contrast to iron-free SiO2 and PBS-only injection controls. Circling behavior was evaluated six days after the intranigral microinjection, considered as a behavioral end-point of brain damage. The apomorphine-induced ipsilateral turns in the treated animals presented significant differences in relation to the control groups, with FeSO4 administration leading to a dramatic phenotype, compared to a milder impact in SiO2-Fe administrated animals. Thus, the use of SiO2-Fe nanoparticles represents a slow iron release system useful to model the gradual iron-accumulation process observed in the SNpc of patients with idiopathic Parkinson's disease.

Nanoparticle-Assisted Liquid Crystal Droplet Sensors Enable Analysis of Low-Concentration Species in Aqueous Medium

We introduce nanoparticle-assisted liquid crystal (LC) droplet-based sensors that allow determination of low-level concentrations of aqueous soluble species. The silica nanoparticles functionalized with mixed monolayers composed of two distinct groups, hydrophobic alkane tail- and charged group-terminated silanes, facilitated ternary physical interactions between the model analytes (methylene blue (MB) or methyl orange (MO)) and the nematic mesogens 5CB (4-cyano-4'-pentylbiphenyl), and the interfacial species of the nanoparticle. The response of the LC droplets was measured upon nanoparticle adsorption as a function of analyte concentration, which was characterized by the optical determination of the configuration distributions of the LC droplets. We highlight the importance of the charging and the composition of the nanoparticle interfaces for analytical purposes that allow accurate determination of the concentration of the analytes on the order of 0.01 ppb. Such a low concentration corresponds to a low interfacial coverage of nanoparticles, indicating the promisingly high sensitivity of the sensor platform to target analytes. Distinct from the past examples of the LC-based sensors, the nanoparticle-assisted LC sensors allow detection of the species that do not directly cause an ordering transition at the LC-water interfaces, which allow a broader range of analytical targets. The sensor platform that we report herein can be easily tunable for a range of target molecules and will find use in the determination of a wide range of micropollutants in aqueous environments.

Enterosorbents in complex therapy of food allergies: a focus on digestive disorders and systemic toxicity in children

The review analyzes mechanisms and concomitant factors in developing IgE-associated allergic diseases provoked by food allergens and discusses clinical symptoms and current approaches for the treatment of food allergies. The expediency of using enterosorbents in complex therapy of food allergies and skin and respiratory manifestations associated with gastroenterological disorders is substantiated. The review summarizes the experience of using enterosorbents in post-Soviet countries to detoxify the human body. In this regard, special attention is paid to the enterosorbent White Coal (Carbowhite) based on silicon dioxide produced by the Ukrainian company OmniFarma.

Engineering nanoparticle toolkits for mRNA delivery

The concept of using mRNA to produce its own medicine in situ in the body makes it an ideal drug candidate, holding great potential to revolutionize the way we approach medicine. The unique characteristics of mRNA, as well as its customizable biomedical functions, call for the rational design of delivery systems to protect and transport mRNA molecules. In this review, a nanoparticle toolkit is presented for the development of mRNA-based therapeutics from a drug delivery perspective. Nano-delivery systems derived from either natural systems or chemical synthesis, in the nature of organic or inorganic materials, are summarised. Delivery strategies in controlling the tissue targeting and mRNA release, as well as the role of nanoparticles in building and boosting the activity of mRNA drugs, have also been introduced. In the end, our insights into the clinical and translational development of mRNA nano-drugs are presented.

Silica nanoparticles induce ovarian granulosa cell apoptosis via activation of the PERK-ATF4-CHOP-ERO1α pathway-mediated IP3R1-dependent calcium mobilization

Ambient particulate matters (PMs) have adverse effects in human and animal female reproductive health. Silica nanoparticles (SNPs), as a major component of PMs, can induce follicular atresia via the promotion of ovarian granulosa cell apoptosis. However, the molecular mechanisms of apoptosis induced by SNPs are not very clear. This work focuses on revealing the mechanisms of ER stress on SNP-induced apoptosis. Our results showed that spherical Stöber SNPs (110 nm, 25.0 mg/kg b.w.) induced follicular atresia via the promotion of granulosa cell apoptosis by intratracheal instillation in vivo; meanwhile, SNPs decreased the viability and increase apoptosis in granulosa cells in vitro. SNPs were taken up and accumulated in the vesicles of granulosa cells. Additionally, our results found that SNPs increased calcium ion (Ca2+) concentration in granulosa cell cytoplasm. Furthermore, SNPs activated ER stress via an increase in the PERK and ATF6 pathway-related protein levels and IP3R1-dependent calcium mobilization via an increase in IP3R1 level. In addition, 4-PBA restored IP3R1-dependent calcium mobilization and decreased apoptosis via the inhibition of ER stress. The ATF4-C/EBP homologous protein (CHOP)-ER oxidoreductase 1 alpha (ERO1α) pathway regulated SNP-induced IP3R1-dependent calcium mobilization and cell apoptosis via ATF4, CHOP, and ERO1α depletion in ovarian granulosa cells. Herein, we demonstrate that ER stress cooperated in SNP-induced ovarian toxicity via activation of IP3R1-mediated calcium mobilization, leading to apoptosis, in which the PERK-ATF4-CHOP-ERO1α pathway plays an essential role in ovarian granulosa cells.

MicroRNA-based therapeutics for inflammatory disorders of the microbiota-gut-brain axis

An emerging but less explored shared pathophysiology across microbiota-gut-brain axis disorders is aberrant miRNA expression, which may represent novel therapeutic targets. miRNAs are small, endogenous non-coding RNAs that are important transcriptional repressors of gene expression. Most importantly, they regulate the integrity of the intestinal epithelial and blood-brain barriers and serve as an important communication channel between the gut microbiome and the host. A well-defined understanding of the mode of action, therapeutic strategies and delivery mechanisms of miRNAs is pivotal in translating the clinical applications of miRNA-based therapeutics. Accumulating evidence links disorders of the microbiota-gut-brain axis with a compromised gut-blood-brain-barrier, causing gut contents such as immune cells and microbiota to enter the bloodstream leading to low-grade systemic inflammation. This has the potential to affect all organs, including the brain, causing central inflammation and the development of neurodegenerative and neuropsychiatric diseases. In this review, we have examined in detail miRNA biogenesis, strategies for therapeutic application, delivery mechanisms, as well as their pathophysiology and clinical applications in inflammatory gut-brain disorders. The research data in this review was drawn from the following databases: PubMed, Google Scholar, and Clinicaltrials.gov. With increasing evidence of the pathophysiological importance for miRNAs in microbiota-gut-brain axis disorders, therapeutic targeting of cross-regulated miRNAs in these disorders displays potentially transformative and translational potential. Further preclinical research and human clinical trials are required to further advance this area of research.

Survival, growth, behavior, hematology and serum biochemistry of mice under different concentrations of orally administered amorphous silica nanoparticle

Silica nanoparticles (SiNPs) are used extensively in consumer products and biomedical research basically due to ease of production and low cost. However, insufficient literature is reported regarding the toxicity and biocompatibility of SiNPs. The present study aimed to investigate the potential role of amorphous SiNPs on survival, growth, behavioral alterations, hematology and serum biochemistry of mice at four concentrations (control, 50, 100 and 150 mg/kg/day) of an oral supplementation for a period of 3 months. Signs of toxicity (lethargy, nausea, coma, tremors, vomiting and diarrhea, etc.) were noted at 9:00 am and 9:00 pm (twice a day) and the body weight of each of these mice was measured every week. The data were subjected to mean, standard deviation (S.D). Moreover, One-Way Analysis of Variance (ANOVA) and Dunnett's test were applied for analysis of statistical significance between groups by using SPSS software, version 20. All the mice survived with minor alterations in behavior and no significant weight changes were observed during the stipulated time period. Complete blood count (CBC) analysis indicated non-significant (P ≥ 0.05) systemic dysfunctions of organ systems. However, there was elevation in the level of AST and ALT in the analysis of serum biochemistry, while the values of all other examined parameters were not-significant (P ≥ 0.05). The study concluded that orally administered large silica nanoparticles up to the dose level of 150 mg/kg/day are nontoxic for the in vivo use in mice.

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.

Adsorption Dynamics of Surface-Modified Silica Nanoparticles at Solid-Liquid Interfaces

Understanding the adsorption dynamics of nanoparticles at solid-liquid interfaces is of paramount importance to engineer nanoparticles for a variety of applications. The nanoparticle surface chemistry is significant for controlling the adsorption dynamics. This study aimed to experimentally examine the adsorption of surface-modified round-shaped silica nanoparticles (with an average diameter of 12 nm), grafted with hydrophobic (propyl chains) and/or hydrophilic (polyethylene glycol chains) agents, at an aqueous solution-silica interface with spherical soda-lime glass beads (diameter of 3 mm) being used as adsorbents. While no measurable adsorption was observed for solely hydrophobic or hydrophilic nanoparticles, a considerable level of adsorption was detected for nanoparticles comprising both hydrophobic and hydrophilic agents. Various kinetic models were employed to model the adsorption dynamics of the responsive nanoparticles. The results demonstrated that the mixed diffusion-kinetics models could predict the dynamics better than the adsorption diffusion models, indicating that the dynamics is controlled by a combination of liquid film diffusion, intra-particle diffusion, and mass action. Additionally, the adsorption of the surface-modified silica nanoparticles onto a mineral silica surface was examined using molecular dynamics simulations. The interaction energy for nanoparticles comprising both hydrophobic and hydrophilic agents was evaluated to be more favorable than that of solely hydrophobic or hydrophilic nanoparticles.

Dye-sensitized lanthanide containing nanoparticles for luminescence based applications

Due to their exceptional luminescent properties, lanthanide (Ln) complexes represent a unique palette of probes in the spectroscopic toolkit. Their extremely weak brightness due to forbidden Ln electronic transitions can be overcome by indirect dye-sensitization from the antenna effect brought by organic ligands. Despite the improvement brought by the antenna effect, (bio)analytical applications with discrete Ln complexes as luminescent markers still suffers from low sensitivity as they are limited by the complex brightness. Thus, there is a need to develop nano-objects that cumulate the spectroscopic properties of multiple Ln ions. This review firstly gives a brief introduction of the spectral properties of lanthanides both in complexes and in nanoparticles (NPs). Then, the research progress of the design of Ln-doped inorganic NPs with capping antennas, Ln-complex encapsulated NPs and Ln-complex surface functionalized NPs is presented along with a summary of the various photosensitizing ligands and of the spectroscopic properties (excited-state lifetime, brightness, quantum yield). The review also emphasizes the problems and limitations encountered over the years and the solutions provided to address them. Finally, a comparison of the advantages and drawbacks of the three types of NP is provided as well as a conclusion about the remaining challenges both in the design of brighter NPs and in the luminescence based applications.

Synthesis of Cellular Silica Using Microbubbles as Templates

In this work, cellular silica was synthesized by using microbubbles as templates, which contain a mixture of argon and silicon tetrafluoride (SiF₄). The latter is generated from decomposition of hexafluorosilicic acid (H₂SiF₆) at ambient conditions. The specific surface area of cellular silica can be as high as 130 m²/g, the size of the cavity is hundreds-of-nanometers, and the thickness of the cavity wall is around 30 nm. The cavity size, apparent packing density, and porosity of cellular silica strongly depend on the nature of the aqueous solutions; the cavity size appears to be negatively proportional to the surface tension, but thickness of cavity walls seems to be weakly affected by the aqueous properties. An attempt was made to introduce aluminum atoms in situ in the second-coordination sphere of Si atoms and/or load aluminum into the silica structure. Cellular silica with large pores facilitate the transfer of large molecules, including polymers and enzymes; thus, it could find applications in (bio)catalysis, sorption, controlled release and separations.

Amorphous silica nanoparticles caused lung injury through the induction of epithelial apoptosis via ROS/Ca2+/DRP1-mediated mitochondrial fission signaling

The adverse effects of amorphous silica nanoparticles (SiNPs) exposure on the respiratory system were increasingly recognized, however, its potential pathogenesis still remains not fully elucidated. So, this study aimed to explore its effects on pulmonary injury, and to investigate related mechanisms. Histological investigations illustrated SiNPs triggered the lung injury, mainly manifested as alveolar structure destruction, collagen deposition, and mitochondrial ultrastructural injury. In particular, SiNPs greatly enhanced pulmonary ROS and TUNEL positive rate in lungs, both of which were positively correlated with lung impairments. Further, the underlying mechanisms were investigated in cultured human bronchial epithelial cells (16HBE). Consistent with the in vivo findings, SiNPs caused the impairments on mitochondrial structure, as well as the activation of ROS generation and oxidative injury. Upon SiNPs stimuli, mitochondrial respiration was greatly inhibited, while Ca2+ overload in cytosol and mitochondria owing to ER calcium release was noticed, resulting in mitochondrial-dependent epithelial apoptosis. More importantly, mitochondrial dynamics was imbalanced toward a fission type, as evidenced by upregulated DRP1 and its phosphorylation at Ser616 (DRP1s616), while downregulated DRP1s637, and also MFN1, MFN2. Mechanistic investigations revealed that the activation of ROS/Ca2+ signaling promoted DRP1-mediated mitochondrial fission by SiNPs, forming a vicious cycle, and ultimately contributing to apoptosis in 16HBE. In summary, our results disclosed SiNPs caused pulmonary injury through the induction of epithelial apoptosis via a ROS/Ca2+/DRP1-mediated mitochondrial fission axis.

Comparative Study on Nanotoxicity in Human Primary and Cancer Cells

Nanomaterial toxicity tests using normal and cancer cells may yield markedly different results. Here, nanomaterial toxicity between cancer and primary human cells was compared to determine the basic cell line selection criteria for nanomaterial toxicity analyses. Specifically, we exposed two cancer (A549 and HepG2) and two normal cell lines (NHBE and HH) cell lines to SiO₂ nanoparticles (NPs) and evaluated the cytotoxicity (MTS assay), cell death mode, and intracellular NP retention. MTS assay results revealed higher sensitivity of HH cells to SiO₂ NPs than HepG2 cells, while no difference was observed between NHBE and A549 cells. In addition, SiO₂ NPs primarily induced necrosis in all the cell lines. Moreover, we evaluated NP accumulation by treating the cell lines with fluorescein-isothiocyanate-labeled SiO₂ NPs. After 48 h of treatment, less than 10% of A549 and HepG2 cells and more than 30% of NHBE and HH cells contained the labeled NPs. Collectively, our results suggest that cell viability, death mode, and intracellular compound accumulation could be assessed using cancer cells. However, the outcomes of certain investigations, such as intracellular NP retention, may differ between cancer and normal cells.

Nanoparticle-based strategies to target HIV-infected cells

Antiretroviral drugs employed for the treatment of human immunodeficiency virus (HIV) infections have remained largely ineffective due to their poor bioavailability, numerous adverse effects, modest uptake in infected cells, undesirable drug-drug interactions, the necessity for long-term drug therapy, and lack of access to tissues and reservoirs. Nanotechnology-based interventions could serve to overcome several of these disadvantages and thereby improve the therapeutic efficacy of antiretrovirals while reducing the morbidity and mortality due to the disease. However, attempts to use nanocarriers for the delivery of anti-retroviral drugs have started gaining momentum only in the past decade. This review explores in-depth the various nanocarriers that have been employed for the treatment of HIV infections highlighting their merits and possible demerits.

Silica nanoparticles cause spermatogenesis dysfunction in mice via inducing cell cycle arrest and apoptosis

The widespread use of silica nanoparticles (SiNPs) has increased the risk of human exposure, which raised concerns about their adverse effects on human health, especially the reproductive system. Previous studies have shown that SiNPs could cause damage to reproductive organs, but the specific mechanism is still unclear. In this study, to investigate the underlying mechanism of male reproductive toxicity induced by SiNPs, 40 male mice at the age of 8 weeks were divided into two groups and then intraperitoneally injected with vehicle control or 10 mg/kg SiNPs per day for one week. The results showed that SiNPs could damage testicular structure, perturb spermatogenesis and reduce serum testosterone levels, leading to a decrease in sperm quality and quantity. In addition, the ROS level in the testis of exposed mice was significantly increased, followed by imbalance of the oxidative redox status. Further study revealed that exposure to SiNPs led to cell cycle arrest and apoptosis, as shown by downregulation of the expression of positive cell cycle regulators and the activation of TNF-α/TNFR Ⅰ-mediated apoptotic pathway. The results demonstrated that SiNPs could cause testicles injure via inducing oxidative stress and DNA damage which led to cell cycle arrest and apoptosis, and thereby resulting in spermatogenic dysfunction.

Organic building blocks at inorganic nanomaterial interfaces

This tutorial review presents our perspective on designing organic molecules for the functionalization of inorganic nanomaterial surfaces, through the model of an "anchor-functionality" paradigm. This "anchor-functionality" paradigm is a streamlined design strategy developed from a comprehensive range of materials (e.g., lead halide perovskites, II-VI semiconductors, III-V semiconductors, metal oxides, diamonds, carbon dots, silicon, etc.) and applications (e.g., light-emitting diodes, photovoltaics, lasers, photonic cavities, photocatalysis, fluorescence imaging, photo dynamic therapy, drug delivery, etc.). The structure of this organic interface modifier comprises two key components: anchor groups binding to inorganic surfaces and functional groups that optimize their performance in specific applications. To help readers better understand and utilize this approach, the roles of different anchor groups and different functional groups are discussed and explained through their interactions with inorganic materials and external environments.

Exploring the role of mesoporous silica nanoparticle in the development of novel drug delivery systems

The biocompatible nature of mesoporous silica nanoparticles (MSN) attracted researchers' attention to deliver therapeutic agents in the treatment of various diseases, where their porous nature, high drug loading efficiency, and suitability to functionalize with a specific ligand of MSN helped to obtain the desired outcome. The application of MSN has been extended to deliver small chemicals to large-sized peptides or proteins to fight against complex diseases. Recently, formulation researches with MSN have been progressed for various non-conventional drug delivery systems, including liposome, microsphere, oro-dispersible film, 3D-printed formulation, and microneedle. Low bulk density, retaining mesoporous structure during downstream processing, and lack of sufficient in vivo studies are some of the important issues towards the success of mesoporous silica-based advanced drug delivery systems. The present review has aimed to evaluate the application of MSN in advanced drug delivery systems to critically analyze the role of MSN in the respective formulation over other functionalized polymers. Finally, an outlook on the future direction of MSN-based advanced drug delivery systems has been drawn against the existing challenges with this platform.

Advances in endocrine toxicity of nanomaterials and mechanism in hormone secretion disorders

The size of nanoparticles is about 1-100 nm. People are exposed to nanoparticles in environmental pollutants from ancient times to the present. With the maturity of nanotechnology in the past two decades, the production of manufactured nanomaterials is rapidly increasing and they are used in a wide range of aerospace, medicine, food, and industrial applications. However, both natural and manufactured nanomaterials have been proved to pose a threat to diverse organs and systems. The endocrine system is critical to maintaining homeostasis. Endocrine disorders are associated with many diseases, including cancer, reduced fertility, and metabolic diseases. Therefore, we review the literatures dealing with the endocrine toxicity of nanomaterial. This review provides an exhaustive description of toxic effects of several common nanomaterials in the endocrine system; more involved are reproductive endocrinology. Then physicochemical factors that determine the endocrine toxicity of nanomaterials are discussed. Furthermore, oxidative stress, changes in steroid production and metabolic enzymes, organelle disruption, and alterations in signal pathways are introduced as potential mechanisms that may cause changes in hormone levels. Finally, we suggest that a risk assessment of endocrine toxicity based on standard procedures and consideration of endocrine disrupting effects of nanomaterials in the field and its environmental and population effects could be future research directions for endocrine toxicity of nanomaterials.

Magnetite-Silica Core/Shell Nanostructures: From Surface Functionalization towards Biomedical Applications—A Review

The interconnection of nanotechnology and medicine could lead to improved materials, offering a better quality of life and new opportunities for biomedical applications, moving from research to clinical applications. Magnetite nanoparticles are interesting magnetic nanomaterials because of the property-depending methods chosen for their synthesis. Magnetite nanoparticles can be coated with various materials, resulting in “core/shell” magnetic structures with tunable properties. To synthesize promising materials with promising implications for biomedical applications, the researchers functionalized magnetite nanoparticles with silica and, thanks to the presence of silanol groups, the functionality, biocompatibility, and hydrophilicity were improved. This review highlights the most important synthesis methods for silica-coated with magnetite nanoparticles. From the presented methods, the most used was the Stöber method; there are also other syntheses presented in the review, such as co-precipitation, sol-gel, thermal decomposition, and the hydrothermal method. The second part of the review presents the main applications of magnetite-silica core/shell nanostructures. Magnetite-silica core/shell nanostructures have promising biomedical applications in magnetic resonance imaging (MRI) as a contrast agent, hyperthermia, drug delivery systems, and selective cancer therapy but also in developing magnetic micro devices.

Tumor vasculature-targeting nanomedicines

Uncontrolled tumor growth and subsequent distant metastasis are highly dependent on an adequate nutrient supply from tumor blood vessels, which have relatively different pathophysiological characteristics from those of normal vasculature. Obviously, strategies targeting tumor vasculature, such as anti-angiogenic drugs and vascular disrupting agents, are attractive methods for cancer therapy. However, the off-target effects and high dose administration of these drug regimens critically restrict their clinical applications. In recent years, nanomedicines focused on tumor vasculature have been shown to be superior to traditional therapeutic methods and do not induce side effects. This review will first highlight the recent development of tumor vasculature-targeting nanomedicines from the following four aspects: 1) angiogenesis-inhibiting nanomedicines (AINs); 2) vasculature-disrupting nanomedicines (VDNs); 3) vasculature infarction nanomedicines (VINs); and 4) vasculature-regulating nanomedicines (VRNs). Furthermore, the design principles, limitations, and future directions are also discussed. STATEMENT OF SIGNIFICANCE: Based on the essential roles of tumor blood vessels, the therapeutic strategies targeting tumor vasculature have exhibited good clinical therapeutic outcomes. However, poor patient adherence to free drug administration limits their clinical usage. Nanomedicines have great potential to overcome the abovementioned obstacle. This review summarizes the tumor-vasculature targeting nanomedicines from four aspects: 1) angiogenesis-inhibiting nanomedicines (AINs); 2) vasculature-disrupting nanomedicines (VDNs); 3) vasculature infarction nanomedicines (VINs); and 4) vasculature regulating nanomedicines (VRNs). In addition, this review provides perspectives on this research field.

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).

Discovery, Optimization, and Clinical Application of Natural Antimicrobial Peptides

Antimicrobial peptides (AMPs) are widespread in multicellular organisms. These structurally diverse molecules are produced as the first line of defense against pathogens such as bacteria, viruses, fungi, and parasites. Also known as host defense peptides in higher eukaryotic organisms, AMPs display immunomodulatory and anticancer activities. During the last 30 years, technological advances have boosted the research on antimicrobial peptides, which have also attracted great interest as an alternative to tackling the antimicrobial resistance scenario mainly provoked by some bacterial and fungal pathogens. However, the introduction of natural AMPs in clinical trials faces challenges such as proteolytic digestion, short half-lives, and cytotoxicity upon systemic and oral application. Therefore, some strategies have been implemented to improve the properties of AMPs aiming to be used as effective therapeutic agents. In the present review, we summarize the discovery path of AMPs, focusing on preclinical development, recent advances in chemical optimization and peptide delivery systems, and their introduction into the market.

Effect of combined exposure to silica nanoparticles and cadmium chloride on female zebrafish ovaries

Silica nanoparticles (SiNPs) and cadmium chloride (CdCl2) are two important environmental pollutants. In previous research, found that SiNPs in zebrafish larvae can amplify the cardiovascular damage caused by cadmium. Whether SiNPs in the ovaries can amplify the adverse effects of cadmium on the zebrafish ovaries is worth studying problem. In this study, sexually mature female zebrafish were used as model organisms and exposed to 1 μmol/L CdCl2 and/or 25 μg/mL SiNPs for 30 days. The results showed that the structure and function of ovaries in the sole and combined exposure groups changed significantly, resulting in reduced ovarian quality, decreased number of mature oocytes, and the development of malformed offspring. A deep-sequencing analysis showed that organisms' lipid metabolism and transportation, estrogen metabolism, and response to the maturation, meiosis, and vitellogenin synthesis of oocytes were significantly affected by single exposure or combined exposure. These findings provide further insights into the harm of cooperation of CdCl2 and/or SiNPs to the aquatic ecosystems.

Probing TGF-β1-induced cytoskeletal rearrangement by fluorescent-labeled silica nanoparticle uptake assay

Cytoskeletal proteins are essential in maintaining cell morphology, proliferation, and viability as well as internalizing molecules in phagocytic and non-phagocytic cells. Orderly aligned cytoskeletons are disturbed by a range of biological processes, such as the epithelial–mesenchymal transition, which is observed in cancer metastasis. Although many biological methods have been developed to detect cytoskeletal rearrangement, simple and quantitative in vitro approaches are still in great demand. Herein, we applied a flow cytometry-based nanoparticle uptake assay to measure the degree of cytoskeletal rearrangement induced by transforming growth factor β1 (TGF-β1). For the assay, silica nanoparticles, selected for their high biocompatibility, were fluorescent-labeled to facilitate quantification with flow cytometry. Human keratinocyte HaCaT cells were treated with different concentrations of TGF-β1 and then exposed to FITC-labeled silica nanoparticles. Increasing concentrations of TGF-β1 induced gradual changes in cytoskeletal rearrangement, as confirmed by conventional assays. The level of nanoparticle uptake increased by TGF-β1 treatment in a dose-dependent manner, indicating that our nanoparticle uptake assay can be used as a quick and non-destructive approach to measure cytoskeletal rearrangement.

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Fluorescent-labeled silica nanoparticles are used to quantify the level of cytoskeletal rearrangement of HaCaT cells following TGF-β1 treatment as measured by flow cytometry.

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Increasing concentrations of TGF-β1 stimulated cytoskeletal rearrangement of HaCaT cells which in turn increased cellular nanoparticle uptake.

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The nanoparticle uptake assay is a useful tool in semi-quantifying phenotypical changes in epidermal keratinocyte HaCaT cells by TGF-β1, which could help the understanding of the epithelial–mesenchymal transition.

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.

Dental Implant Nano-Engineering: Advances, Limitations and Future Directions

Titanium (Ti) and its alloys offer favorable biocompatibility, mechanical properties and corrosion resistance, which makes them an ideal material choice for dental implants. However, the long-term success of Ti-based dental implants may be challenged due to implant-related infections and inadequate osseointegration. With the development of nanotechnology, nanoscale modifications and the application of nanomaterials have become key areas of focus for research on dental implants. Surface modifications and the use of various coatings, as well as the development of the controlled release of antibiotics or proteins, have improved the osseointegration and soft-tissue integration of dental implants, as well as their antibacterial and immunomodulatory functions. This review introduces recent nano-engineering technologies and materials used in topographical modifications and surface coatings of Ti-based dental implants. These advances are discussed and detailed, including an evaluation of the evidence of their biocompatibility, toxicity, antimicrobial activities and in-vivo performances. The comparison between these attempts at nano-engineering reveals that there are still research gaps that must be addressed towards their clinical translation. For instance, customized three-dimensional printing technology and stimuli-responsive, multi-functional and time-programmable implant surfaces holds great promise to advance this field. Furthermore, long-term in vivo studies under physiological conditions are required to ensure the clinical application of nanomaterial-modified dental implants.

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.

Emergence of nano silica for oil and gas well cementing: application, challenges, and future scope

Nanotechnology has opened up a plethora of opportunities and has acquired extreme importance in a myriad of fields to produce enhanced materials. Their special properties make them sustainable for industrial purposes. One of the most crucial processes in the petroleum and geothermal industries is cementing. Various classes of Portland cement are used according to API classifications. The conventional Portland cement fails to perform its function at high pressure and high temperature (HPHT) conditions. Hence, various admixtures are used to improve its properties. HPHT conditions not only have a bad impact on Portland cement by affecting its rheological properties but also reduce its strength, porosity, and permeability. So, additives like nano silica are used to improve its properties. Better compressive strength, low porosity and permeability, higher yield stress, and reduced setting time are some of the major properties that improve by the use of nano silica. This paper discusses in detail the different types of cement, cementing processes, failure of Portland cement, and effect of nano silica as an admixture on the compressive strength, rheology, porosity, and permeability of the cement. Furthermore, the upcoming challenges in cementing are discussed along with future potential in this field.

Melatonin-Loaded Nanocarriers: New Horizons for Therapeutic Applications

The use of nanosized particles has emerged to facilitate selective applications in medicine. Drug-delivery systems represent novel opportunities to provide stricter, focused, and fine-tuned therapy, enhancing the therapeutic efficacy of chemical agents at the molecular level while reducing their toxic effects. Melatonin (N-acetyl-5-methoxytriptamine) is a small indoleamine secreted essentially by the pineal gland during darkness, but also produced by most cells in a non-circadian manner from which it is not released into the blood. Although the therapeutic promise of melatonin is indisputable, aspects regarding optimal dosage, biotransformation and metabolism, route and time of administration, and targeted therapy remain to be examined for proper treatment results. Recently, prolonged release of melatonin has shown greater efficacy and safety when combined with a nanostructured formulation. This review summarizes the role of melatonin incorporated into different nanocarriers (e.g., lipid-based vesicles, polymeric vesicles, non-ionic surfactant-based vesicles, charge carriers in graphene, electro spun nanofibers, silica-based carriers, metallic and non-metallic nanocomposites) as drug delivery system platforms or multilevel determinations in various in vivo and in vitro experimental conditions. Melatonin incorporated into nanosized materials exhibits superior effectiveness in multiple diseases and pathological processes than does free melatonin; thus, such information has functional significance for clinical intervention.

Polythiolactone-Decorated Silica Particles: A Versatile Approach for Surface Functionalization, Catalysis and Encapsulation

The surface chemistry of colloidal silica has tremendous effects on its properties and applications. Commonly the design of silica particles is based on their de novo synthesis followed by surface functionalization leading to tailormade properties for a specific purpose. Here, the design of robust "precursor" polymer-decorated silica nano- and microparticles is demonstrated, which allows for easy post-modification by polymer embedded thiolactone chemistry. To obtain this organic-inorganic hybrid material, silica particles (SiO2 P) were functionalized via surface-initiated atom transfer radical polymerization (SI-ATRP) with poly(2-hydroxyethyl acrylate) (PHEA)-poly(thiolactone acrylamide (PThlAm) co-polymer brushes. Exploiting the versatility of thiolactone post-modification, a system was developed that could be used in three exemplary applications: 1) the straightforward molecular post-functionalization to tune the surface polarity, and therefore the dispersibility in various solvents; 2) the immobilization of metal nanoparticles into the polymer brushes via the in situ formation of free thiols that preserved catalytic activity in a model reaction; 3) the formation of redox-responsive, permeable polymer capsules by crosslinking the thiolactone moieties with cystamine dihydrochloride (CDH) followed by dissolution of the silica core.

Toward Point-of-Care Diagnostics to Monitor MMP-9 and TNF-α Levels in Inflammatory Bowel Disease

We have investigated the association of matrix metallopeptidase 9 (MMP-9) and tumor necrosis factor α (TNF-α) levels with colitis severity using an established IL10-/- mouse model, which reflects the severity of inflammation in humans with inflammatory bowel disease (IBD). We found that MMP-9 and TNF-α correlated with colitis severity. In parallel, we developed assays to detect fecal MMP-9 and serum TNF-α using "cap and release" mesoporous silica nanoparticles (MSNs). MMP-9 peptide substrates as "caps" were attached to dye-loaded MSNs. The introduction of MMP-9 resulted in substrate cleavage and subsequent dye release, which was rapidly detected using a fluorometer. For TNF-α, an anti-TNF antibody was used as the "cap". The introduction of TNF-α antigen leads to the release of the dyes because the antigen binds more strongly to the antibody cap. The MSN-based assays can detect MMP-9 and TNF-α effectively, although signal amplification is required to meet clinical sensitivity.

Are Biogenic and Pyrogenic Mesoporous SiO2 Nanoparticles Safe for Normal Cells?

Silicon dioxide, in the form of nanoparticles, possesses unique physicochemical properties (size, shape, and a large surface to volume ratio). Therefore, it is one of the most promising materials used in biomedicine. In this paper, we compare the biological effects of both mesoporous silica nanoparticles extracted from Urtica dioica L. and pyrogenic material. Both SEM and TEM investigations confirmed the size range of tested nanoparticles was between 6 and 20 nanometers and their amorphous structure. The cytotoxic activity of the compounds and intracellular ROS were determined in relation to cells HMEC-1 and erythrocytes. The cytotoxic effects of SiO₂ NPs were determined after exposure to different concentrations and three periods of incubation. The same effects for endothelial cells were tested under the same range of concentrations but after 2 and 24 h of exposure to erythrocytes. The cell viability was measured using spectrophotometric and fluorimetric assays, and the impact of the nanoparticles on the level of intracellular ROS. The obtained results indicated that bioSiO₂ NPs, present higher toxicity than pyrogenic NPs and have a higher influence on ROS production. Mesoporous silica nanoparticles show good hemocompatibility but after a 24 h incubation of erythrocytes with silica, the increase in hemolysis process, the decrease in osmotic resistance of red blood cells, and shape of erythrocytes changed were observed.

PEG-Coated Large Mesoporous Silicas as Smart Platform for Protein Delivery and Their Use in a Collagen-Based Formulation for 3D Printing

Silica-based mesoporous systems have gained great interest in drug delivery applications due to their excellent biocompatibility and high loading capability. However, these materials face challenges in terms of pore-size limitations since they are characterized by nanopores ranging between 6-8 nm and thus unsuitable to host large molecular weight molecules such as proteins, enzymes and growth factors (GFs). In this work, for an application in the field of bone regeneration, large-pore mesoporous silicas (LPMSs) were developed to vehicle large biomolecules and release them under a pH stimulus. Considering bone remodeling, the proposed pH-triggered mechanism aims to mimic the release of GFs encased in the bone matrix due to bone resorption by osteoclasts (OCs) and the associated pH drop. To this aim, LPMSs were prepared by using 1,3,5-trimethyl benzene (TMB) as a swelling agent and the synthesis solution was hydrothermally treated and the influence of different process temperatures and durations on the resulting mesostructure was investigated. The synthesized particles exhibited a cage-like mesoporous structure with accessible pores of diameter up to 23 nm. LPMSs produced at 140 °C for 24 h showed the best compromise in terms of specific surface area, pores size and shape and hence, were selected for further experiments. Horseradish peroxidase (HRP) was used as model protein to evaluate the ability of the LPMSs to adsorb and release large biomolecules. After HRP-loading, LPMSs were coated with a pH-responsive polymer, poly(ethylene glycol) (PEG), allowing the release of the incorporated biomolecules in response to a pH decrease, in an attempt to mimic GFs release in bone under the acidic pH generated by the resorption activity of OCs. The reported results proved that PEG-coated carriers released HRP more quickly in an acidic environment, due to the protonation of PEG at low pH that catalyzes polymer hydrolysis reaction. Our findings indicate that LPMSs could be used as carriers to deliver large biomolecules and prove the effectiveness of PEG as pH-responsive coating. Finally, as proof of concept, a collagen-based suspension was obtained by incorporating PEG-coated LPMS carriers into a type I collagen matrix with the aim of designing a hybrid formulation for 3D-printing of bone scaffolds.

Recent Advances in miRNA Delivery Systems

MicroRNAs (miRNAs) represent a family of short non-coding regulatory RNA molecules that are produced in a tissue and time-specific manner to orchestrate gene expression post-transcription. MiRNAs hybridize to target mRNA(s) to induce translation repression or mRNA degradation. Functional studies have demonstrated that miRNAs are engaged in virtually every physiological process and, consequently, miRNA dysregulations have been linked to multiple human pathologies. Thus, miRNA mimics and anti-miRNAs that restore miRNA expression or downregulate aberrantly expressed miRNAs, respectively, are highly sought-after therapeutic strategies for effective manipulation of miRNA levels. In this regard, carrier vehicles that facilitate proficient and safe delivery of miRNA-based therapeutics are fundamental to the clinical success of these pharmaceuticals. Here, we highlight the strengths and weaknesses of current state-of-the-art viral and non-viral miRNA delivery systems and provide perspective on how these tools can be exploited to improve the outcomes of miRNA-based therapeutics.

Silica-Based Nanoparticles as Drug Delivery Vehicles for Prostate Cancer Treatment

Prostate cancer (PCa) is one of the most commonly diagnosed cancers and is the fifth common cause of cancer-related mortality in men. Current methods for PCa treatment are insufficient owing to the challenges related to the non-specificity, instability and side effects caused by the drugs and therapy agents. These drawbacks can be mitigated by the design of a suitable drug delivery system that can ensure targeted delivery and minimise side effects. Silica based nanoparticles (SBNPs) have emerged as one of the most versatile materials for drug delivery due to their tunable porosities, high surface area and tremendous capacity to load various sizes and chemistry of drugs. This review gives a brief overview of the diagnosis and current treatment strategies for PCa outlining their existing challenges. It critically analyzes the design, development and application of pure, modified and hybrid SBNPs based drug delivery systems in the treatment of PCa, their advantages and limitations.

Direct preparation of porous cellulose microspheres via a self-growth process on bamboo fibers and their functionalization for specific adsorption of histidine-rich proteins

The traditional preparation of cellulose microspheres always involves tedious synthetic procedures (e.g., dissolution, emulsification and regeneration) and inevitable organic solvents, which undergoes both high production cost and environmental contamination. To overcome these issues, a feasible and green synthesis strategy is proposed to construct porous cellulose microspheres (PCMs) via one-step spontaneous formation relying on sodium periodate oxidation of pure bamboo fibers. By this strategy, a cluster of robust cellulose microspheres grow up on the surface of bamboo fibers in aqueous phase through amorphous oxidized cellulose self-assembly accumulation and then drop out when their sizes increase to about 15 µm. After being immobilized with Cu(II), the prepared cellulose microspheres serve as metal affinity adsorbent for proteins adsorption, showing high adsorption capacity, good selectivity and excellent reusability for bovine hemoglobin (BHb). Together with green and easy synthesis, the novel cellulose microspheres show a promising alternative to commercially available adsorbent support.

Tailoring of silica-based nanoporous pod by spermidine multi-activity

Ubiquitous in nature, polyamines (PAs) are a class of low-molecular aliphatic amines critically involved in cell growth, survival and differentiation. The polycation behavior is validated as a successful strategy in delivery systems to enhance oligonucleotide loading and cellular uptake. In this study, the chemical features and the functional roles of the PA spermidine are synergistically exploited in the synthesis and bioactive functionalization of SiO2-based structures. Inspired by biosilicification, the role of spermidine is assessed both as catalyst and template in a biomimetic one-pot synthesis of dense silica-based particles (SPs) and as a competitive agent in an interfacial reassembly strategy, to empty out SPs and generate spermidine-decorated hollow silica nanoporous pods (spd-SNPs). Spermidine bioactivity is then employed for targeting tumor cell over-expressed polyamine transport system (PTS) and for effective delivery of functional miRNA into melanoma cells. Spermidine decoration promotes spd-SNP cell internalization mediated by PTS and along with hollow structure enhances oligonucleotide loading. Accordingly, the functional delivery of the tumor suppressor miR-34a 3p resulted in intracellular accumulation of histone-complexed DNA fragments associated with apoptosis. Overall, the results highlight the potential of spd-SNP as a multi-agent anticancer therapy.

Ascorbic Acid-PEI Carbon Dots with Osteogenic Effects as miR-2861 Carriers to Effectively Enhance Bone Regeneration

Nucleic acid transfer has shown significant potential in the treatment of bone damage because of its long lasting local effect and lower cost. Nonviral vectors, such as nanomaterials, with higher biocompatibility are increasedly applied in the study of bone defect repair. Carbon dots with various reactive groups on the surface not only provide a unique surface to carry therapeutic genes, but also some carbon dots have been reported to promote osteogenic differentiation. The bone regeneration effect of carbon dots in vivo, however, is rarely investigated. MiR-2861 has revealed osteogenic differentiation effects. In the current study, we created ascorbic acid-PEI carbon dots (CD), which were able to carry miR-2861, by the microwave-assisted pyrolysis method. Results demonstrated that CD had excellent fluorescence stability leading to good fluorescence imaging in vitro and in vivo. CD was efficiently internalized into bone marrow stromal cells (BMSCs) through the clathrin-mediated endocytosis pathway and distributed in the mitochondria, endoplasmic reticulum, lysosome, and nucleus. Results from alkaline phosphatase staining, alizarin red staining, and reverse transcription real-time PCR (RT-QPCR) showed that our CD indeed had osteogenic effects in vitro. Flow cytometry data indicated that CD could efficiently deliver miR-2861 into BMSCs in vitro, and CD carrying miR-2861 (CD@miR) had the strongest osteogenic effects. Analyses of hematology, serum biochemistry, and histology showed that CD and CD@miR did not have cytotoxicity and had higher biocompatibility in vivo. Most interestingly, CD and miR-2861 in the CD@miR could act synergistically to promote osteogenic differentiation in vitro and new bone regeneration in vivo remarkably. Our results clearly indicate that the osteogenic CD delivering osteogenic therapeutic gene, miR-2861, can obtain much stronger bone regeneration ability, suggesting that our CD has great potential in future clinical application.

The Effects of Single Nucleotide Polymorphisms in Cancer RNAi Therapies

Simple Summary

Despite the recent progress in RNAi delivery of siRNA-based therapeutics for cancer therapy, the presence of single nucleotide polymorphisms (SNPs) in the general population could dramatically reduce the effectiveness of RNAi therapy. Their ubiquitous presence can also lead to unpredictable and adverse side effects. Because both SNPs and somatic mosaicisms have also been implicated in a number of human diseases including cancer, however, these specific changes offer the ability to selectively and efficiently target cancer cells. Here, we discuss how SNPs influence the development and success of novel anticancer RNAi therapies.

Abstract

Tremendous progress in RNAi delivery methods and design has allowed for the effective development of siRNA-based therapeutics that are currently under clinical investigation for various cancer treatments. This approach has the potential to revolutionize cancer therapy by providing the ability to specifically downregulate or upregulate the mRNA of any protein of interest. This exquisite specificity, unfortunately, also has a downside. Genetic variations in the human population are common because of the presence of single nucleotide polymorphisms (SNPs). SNPs lead to synonymous and non-synonymous changes and they occur once in every 300 base pairs in both coding and non-coding regions in the human genome. Much less common are the somatic mosaicism variations associated with genetically distinct populations of cells within an individual that is derived from postzygotic mutations. These heterogeneities in the population can affect the RNAi’s efficacy or more problematically, which can lead to unpredictable and sometimes adverse side effects. From a more positive viewpoint, both SNPs and somatic mosaicisms have also been implicated in human diseases, including cancer, and these specific changes could offer the ability to effectively and, more importantly, selectively target the cancer cells. In this review, we discuss how SNPs in the human population can influence the development and success of novel anticancer RNAi therapies and the importance of why SNPs should be carefully considered.

Comprehensive Survey on Nanobiomaterials for Bone Tissue Engineering Applications

One of the most important ideas ever produced by the application of materials science to the medical field is the notion of biomaterials. The nanostructured biomaterials play a crucial role in the development of new treatment strategies including not only the replacement of tissues and organs, but also repair and regeneration. They are designed to interact with damaged or injured tissues to induce regeneration, or as a forest for the production of laboratory tissues, so they must be micro-environmentally sensitive. The existing materials have many limitations, including impaired cell attachment, proliferation, and toxicity. Nanotechnology may open new avenues to bone tissue engineering by forming new assemblies similar in size and shape to the existing hierarchical bone structure. Organic and inorganic nanobiomaterials are increasingly used for bone tissue engineering applications because they may allow to overcome some of the current restrictions entailed by bone regeneration methods. This review covers the applications of different organic and inorganic nanobiomaterials in the field of hard tissue engineering.

Increased Uptake of Silica Nanoparticles in Inflamed Macrophages but Not upon Co-Exposure to Micron-Sized Particles

Silica nanoparticles (NPs) are widely used in various industrial and biomedical applications. Little is known about the cellular uptake of co-exposed silica particles, as can be expected in our daily life. In addition, an inflamed microenvironment might affect a NP’s uptake and a cell’s physiological response. Herein, prestimulated mouse J774A.1 macrophages with bacterial lipopolysaccharide were post-exposed to micron- and nanosized silica particles, either alone or together, i.e., simultaneously or sequentially, for different time points. The results indicated a morphological change and increased expression of tumor necrosis factor alpha in lipopolysaccharide prestimulated cells, suggesting a M1-polarization phenotype. Confocal laser scanning microscopy revealed the intracellular accumulation and uptake of both particle types for all exposure conditions. A flow cytometry analysis showed an increased particle uptake in lipopolysaccharide prestimulated macrophages. However, no differences were observed in particle uptakes between single- and co-exposure conditions. We did not observe any colocalization between the two silica (SiO₂) particles. However, there was a positive colocalization between lysosomes and nanosized silica but only a few colocalized events with micro-sized silica particles. This suggests differential intracellular localizations of silica particles in macrophages and a possible activation of distinct endocytic pathways. The results demonstrate that the cellular uptake of NPs is modulated in inflamed macrophages but not in the presence of micron-sized particles.

Functionalization of Magnetic Nanoparticles by Folate as Potential MRI Contrast Agent for Breast Cancer Diagnostics

In recent years, the intrinsic magnetic properties of magnetic nanoparticles (MNPs) have made them one of the most promising candidates for magnetic resonance imaging (MRI). This study aims to evaluate the effect of different coating agents (with and without targeting agents) on the magnetic property of MNPs. In detail, iron oxide nanoparticles (IONPs) were prepared by the polyol method. The nanoparticles were then divided into two groups, one of which was coated with silica (SiO2) and hyperbranched polyglycerol (HPG) (SPION@SiO2@HPG); the other was covered by HPG alone (SPION@HPG). In the following section, folic acid (FA), as a targeting agent, was attached on the surface of nanoparticles. Physicochemical properties of nanostructures were characterized using Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and a vibrating sample magnetometer (VSM). TEM results showed that SPION@HPG was monodispersed with the average size of about 20 nm, while SPION@SiO2@HPG had a size of about 25 nm. Moreover, HPG coated nanoparticles had much lower magnetic saturation than the silica coated ones. The MR signal intensity of the nanostructures showed a relation between increasing the nanoparticle concentrations inside the MCF-7 cells and decreasing the signal related to the T2 relaxation time. The comparison of coating showed that SPION@SiO2@HPG (with/without a targeting agent) had significantly higher r2 value in comparison to Fe3O4@HPG. Based on the results of this study, the Fe3O4@SiO2@HPG-FA nanoparticles have shown the best magnetic properties, and can be considered promising contrast agents for magnetic resonance imaging applications.

Advancing bioinks for 3D bioprinting using reactive fillers: A review

The growing demand for personalized implants and tissue scaffolds requires advanced biomaterials and processing strategies for the fabrication of three-dimensional (3D) structures mimicking the complexity of the extracellular matrix. During the last years, biofabrication approaches like 3D printing of cell-laden (soft) hydrogels have been gaining increasing attention to design such 3D functional environments which resemble natural tissues (and organs). However, often these polymeric hydrogels show poor stability and low printing fidelity and hence various approaches in terms of multi-material mixtures are being developed to enhance pre- and post-printing features as well as cytocompatibility and post-printing cellular development. Additionally, bioactive properties improve the binding to the surrounding (host) tissue at the implantation site. In this review we focus on the state-of-the-art of a particular type of heterogeneous bioinks, which are composed of polymeric hydrogels incorporating inorganic bioactive fillers. Such systems include isotropic and anisotropic silicates like bioactive glasses and nanoclays or calcium-phosphates like hydroxyapatite (HAp), which provide in-situ crosslinking effects and add extra functionality to the matrix, for example mineralization capability. The present review paper discusses in detail such bioactive composite bioink systems based on the available literature, revealing that a great variety has been developed with substantially improved bioprinting characteristics, in comparison to the pure hydrogel counterparts, and enabling high viability of printed cells. The analysis of the results of the published studies demonstrates that bioactive fillers are a promising addition to hydrogels to print stable 3D constructs for regeneration of tissues. Progress and challenges of the development and applications of such composite bioink approaches are discussed and avenues for future research in the field are presented. STATEMENT OF SIGNIFICANCE: Biofabrication, involving the processing of biocompatible hydrogels including cells (bioinks), is being increasingly applied for developing complex tissue and organ mimicking structures. A variety of multi-material bioinks is being investigated to bioprint 3D constructs showing shape stability and long-term biological performance. Composite hydrogel bioinks incorporating inorganic bioreactive fillers for 3D bioprinting are the subject of this review paper. Results reported in the literature highlight the effect of bioactive fillers on bioink properties, printability and on cell behavior during and after printing and provide important information for optimizing the design of future bioinks for biofabrication, exploiting the extra functionalities provided by inorganic fillers. Further functionalization with drugs/growth factors can target enhanced printability and local drug release for more specialized biomedical therapies.