In vivo biodistribution and pharmacokinetics of silica nanoparticles as a function of geometry, porosity and surface characteristics

The Promise and Potential of Metal-Organic Frameworks and Covalent Organic Frameworks in Vaccine Nanotechnology

The immune system's complexity and ongoing evolutionary struggle against deleterious pathogens underscore the value of vaccination technologies, which have been bolstering human immunity for over two centuries. Despite noteworthy advancements over these 200 years, three areas remain recalcitrant to improvement owing to the environmental instability of the biomolecules used in vaccines─the challenges of formulating them into controlled release systems, their need for constant refrigeration to avoid loss of efficacy, and the requirement that they be delivered via needle owing to gastrointestinal incompatibility. Nanotechnology, particularly metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), has emerged as a promising avenue for confronting these challenges, presenting a new frontier in vaccine development. Although these materials have been widely explored in the context of drug delivery, imaging, and cancer immunotherapy, their role in immunology and vaccine-related applications is a recent yet rapidly developing field. This review seeks to elucidate the prospective use of MOFs and COFs for biomaterial stabilization, eliminating the necessity for cold chains, enhancing antigen potency as adjuvants, and potentializing needle-free delivery of vaccines. It provides an expansive and critical viewpoint on this rapidly evolving field of research and emphasizes the vital contribution of chemists in driving further advancements.

In vitro and in vivo toxicity of thiolated and PEGylated organosilica nanoparticles

This study comprises the comprehensive toxicological assessment of thiolated organosilica nanoparticles (NPs) synthesised from 3-mercaptopropyltrimethoxysilane (MPTS). We investigated the influence of three different types of nanoparticles synthesised from 3-mercaptopropyltrimethoxysilane: the starting thiolated silica (Si-NP-SH) and their derivatives prepared by surface PEGylation with PEG 750 (Si-NP-PEG750) and 5000 Da (Si-NP-PEG5000) on biological subjects from in vitro to in vivo experiments to explore the possible applications of those nanoparticles in biomedical research. As a result of this study, we generated a comprehensive understanding of the toxicological properties of these nanoparticles, including their cytotoxicity in different cell lines, hemolytic properties, in vitro localisation, mucosal irritation properties and biodistribution in BALB/c mice. Our findings indicate that all three types of nanoparticles can be considered safe and have promising prospects for use in biomedical applications. Nanoparticles did not affect the viability of HPF, MCF7, HEK293 and A549 cell lines at low concentrations (up to 100 µg/mL); moreover, they did not cause organ damage to BALB/c mice at concentrations of 10 mg/kg. The outcomes of this study enhance our understanding of the impact of organosilica nanoparticles on health and the environment, which is vital for developing silica nanoparticle-based drug delivery systems and provides opportunities to expand the applications of organosilica nanoparticles.

Biosynthesis and biocompatibility evaluation of zinc oxide nanoparticles prepared using Priestia megaterium bacteria

The current study aimed to find an effective, simple, ecological, and nontoxic method for bacterial green synthesis of zinc oxide nanoparticles (ZnONPs) using the bacterial strain Priestia megaterium BASMA 2022 (OP572246). The biosynthesis was confirmed by the change in color of the cell-free supernatant added to the zinc nitrate from yellow to pale brown. The Priestia megaterium zinc oxide nanoparticles (Pm/ZnONPs) were characterized using UV-Vis spectroscopy, high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and zeta potential. The Pm/ZnONPs characterization showed that they have a size ranging between 5.77 and 13.9 nm with a semi-sphere shape that is coated with a protein-carbohydrate complex. An EDX analysis of the Pm/ZnONPs revealed the presence of the shield matrix, which was composed of carbon, nitrogen, oxygen, chlorine, potassium, sodium, aluminum, sulfur, and zinc. The results of the FTIR analysis showed that the reduction and stabilization of the zinc salt solution were caused by the presence of O-H alcohols and phenols, O=C=O stretching of carbon dioxide, N=C=S stretching of isothiocyanate, and N-H bending of amine functional groups. The produced ZnONPs had good stability with a charge of - 16.2 mV, as evidenced by zeta potential analysis. The MTT assay revealed IC50 values of 8.42% and 200%, respectively, for the human A375 skin melanoma and human bone marrow 2M-302 cell lines. These findings revealed that the obtained Pm/ZnONPs have the biocompatibility to be applied in the pharmaceutical and biomedical sectors.

Antimicrobial peptide-conjugated phage-mimicking nanoparticles exhibit potent bactericidal action against Streptococcus pyogenes in murine wound infection models

Streptococcus pyogenes is a causative agent for strep throat, impetigo, and more invasive diseases. The main reason for the treatment failure of streptococcal infections is increased antibiotic resistance. In recent years, infectious diseases caused by pyogenic streptococci resistant to multiple antibiotics have been rising with a significant impact on public health and the veterinary industry. The development of antibiotic resistance and the resulting emergence of multidrug-resistant bacteria have become primary threats to the public health system, commonly leading to nosocomial infections. Many researchers have turned their focus to developing alternative classes of antibacterial agent based on various nanomaterials. We have developed an antibiotic-free nanoparticle system inspired by naturally occurring bacteriophages to fight antibiotic-resistant bacteria. Our phage-mimicking nanoparticles (PhaNPs) display structural mimicry of protein-turret distribution on the head structure of bacteriophages. By mimicking phages, we can take advantage of their evolutionary constant shape and high antibacterial activity while avoiding the immune reactions of the human body experienced by biologically derived phages. We describe the synthesis of hierarchically arranged core-shell nanoparticles, with a silica core conjugated with silver-coated gold nanospheres to which we have chemisorbed the synthetic antimicrobial peptide Syn-71 on the PhaNPs surface, and increased the rapidity of the antibacterial activity of the nanoparticles (PhaNP@Syn71). The antibacterial effect of the PhaNP@Syn71 was tested in vitro and in vivo in mouse wound infection models. In vitro, results showed a dose-dependent complete inhibition of bacterial growth (>99.99%). Cytocompatibility testing on HaCaT human skin keratinocytes showed minimal cytotoxicity of PhaNP@Syn71, being comparable to the vehicle cytotoxicity levels even at higher concentrations, thus proving that our design is biocompatible with human cells. There was a minimum cutoff dosage above which there was no evolution of resistance after prolonged exposure to sub-MIC dosages of PhaNP@Syn71. Application of PhaNP@Syn71 to a mouse wound infection model exhibited high biocompatibility in vivo while showing immediate stabilization of the wound size, and infection free wound healing. Our results suggest the robust utility of antimicrobial peptide-conjugated phage-mimicking nanoparticles as a highly effective antibacterial system that can combat bacterial infections consistently while avoiding the emergence of resistant bacterial strains.

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.

Targeted Delivery of the Pan-Inflammasome Inhibitor MM01 as an Alternative Approach to Acute Lung Injury Therapy

Acute lung injury (ALI) is a severe pulmonary disorder responsible for high percentage of mortality and morbidity in intensive care unit patients. Current treatments are ineffective, so the development of efficient and specific therapies is an unmet medical need. The activation of NLPR3 inflammasome during ALI produces the release of proinflammatory factors and pyroptosis, a proinflammatory form of cell death that contributes to lung damage spreading. Herein, it is demonstrated that modulating inflammasome activation through inhibition of ASC oligomerization by the recently described MM01 compound can be an alternative pharmacotherapy against ALI. Besides, the added efficacy of using a drug delivery nanosystem designed to target the inflamed lungs is determined. The MM01 drug is incorporated into mesoporous silica nanoparticles capped with a peptide (TNFR-MM01-MSNs) to target tumor necrosis factor receptor-1 (TNFR-1) to proinflammatory macrophages. The prepared nanoparticles can deliver the cargo in a controlled manner after the preferential uptake by proinflammatory macrophages and exhibit anti-inflammatory activity. Finally, the therapeutic effect of MM01 free or nanoparticulated to inhibit inflammatory response and lung injury is successfully demonstrated in lipopolysaccharide-mouse model of ALI. The results suggest the potential of pan-inflammasome inhibitors as candidates for ALI therapy and the use of nanoparticles for targeted lung delivery.

Nanoparticles systemically biodistribute to regenerating skeletal muscle in DMD

Skeletal muscle disease severity can often progress asymmetrically across muscle groups and heterogeneously within tissues. An example is Duchenne Muscular Dystrophy (DMD) in which lack of dystrophin results in devastating skeletal muscle wasting in some muscles whereas others are spared or undergo hypertrophy. An efficient, non-invasive approach to identify sites of asymmetry and degenerative lesions could enable better patient monitoring and therapeutic targeting of disease. In this study, we utilized a versatile intravenously injectable mesoporous silica nanoparticle (MSNP) based nanocarrier system to explore mechanisms of biodistribution in skeletal muscle of mdx mouse models of DMD including wildtype, dystrophic, and severely dystrophic mice. Moreover, MSNPs could be imaged in live mice and whole muscle tissues enabling investigation of how biodistribution is altered by different types of muscle pathology such as inflammation or fibrosis. We found MSNPs were tenfold more likely to aggregate within select mdx muscles relative to wild type, such as gastrocnemius and quadriceps. This was accompanied by decreased biodistribution in off-target organs. We found the greatest factor affecting preferential delivery was the regenerative state of the dystrophic skeletal muscle with the highest MSNP abundance coinciding with the regions showing the highest level of embryonic myosin staining and intramuscular macrophage uptake. To demonstrate, muscle regeneration regulated MSNP distribution, we experimentally induced regeneration using barium chloride which resulted in a threefold increase of intravenously injected MSNPs to sites of regeneration 7 days after injury. These discoveries provide the first evidence that nanoparticles have selective biodistribution to skeletal muscle in DMD to areas of active regeneration and that nanoparticles could enable diagnostic and selective drug delivery in DMD skeletal muscle.

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.

Metal-based nanomaterials and nanocomposites as promising frontier in cancer chemotherapy

Cancer is a disease associated with complex pathology and one of the most prevalent and leading reasons for mortality in the world. Current chemotherapy has challenges with cytotoxicity, selectivity, multidrug resistance, and the formation of stemlike cells. Nanomaterials (NMs) have unique properties that make them useful for various diagnostic and therapeutic purposes in cancer research. NMs can be engineered to target cancer cells for early detection and can deliver drugs directly to cancer cells, reducing side effects and improving treatment efficacy. Several of NMs can also be used for photothermal therapy to destroy cancer cells or enhance immune response to cancer by delivering immune-stimulating molecules to immune cells or modulating the tumor microenvironment. NMs are being modified to overcome issues, such as toxicity, lack of selectivity, increase drug capacity, and bioavailability, for a wide spectrum of cancer therapies. To improve targeted drug delivery using nano-carriers, noteworthy research is required. Several metal-based NMs have been studied with the expectation of finding a cure for cancer treatment. In this review, the current development and the potential of plant and metal-based NMs with their effects on size and shape have been discussed along with their more effective usage in cancer diagnosis and treatment.

Enhancing Targeted Therapy in Breast Cancer by Ultrasound-Responsive Nanocarriers

Currently, the response to cancer treatments is highly variable, and severe side effects and toxicity are experienced by patients receiving high doses of chemotherapy, such as those diagnosed with triple-negative breast cancer. The main goal of researchers and clinicians is to develop new effective treatments that will be able to specifically target and kill tumor cells by employing the minimum doses of drugs exerting a therapeutic effect. Despite the development of new formulations that overall can increase the drugs’ pharmacokinetics, and that are specifically designed to bind overexpressed molecules on cancer cells and achieve active targeting of the tumor, the desired clinical outcome has not been reached yet. In this review, we will discuss the current classification and standard of care for breast cancer, the application of nanomedicine, and ultrasound-responsive biocompatible carriers (micro/nanobubbles, liposomes, micelles, polymeric nanoparticles, and nanodroplets/nanoemulsions) employed in preclinical studies to target and enhance the delivery of drugs and genes to breast cancer.

Current status of silica-based nanoparticles as therapeutics and its potential as therapies against viruses

In the past decade, interest in nanoparticles for clinical indications has been steadily gaining traction. Most recently, Lipid Nanoparticles (LNP) have been used successfully to construct the SARS-CoV-2 mRNA vaccines for rapid pandemic response. Similarly, silica is another nanomaterial which holds much potential to create nanomedicines against pathogens of interest. One major advantage of silica-based nanoparticles is its crystalline and highly ordered structure, which can be specifically tuned to achieve the desired properties needed for clinical applications. Increasingly, clinical research has shown the potential of silica nanoparticles not only as an antiviral, but also its ability as a delivery system for antiviral small molecules and vaccines against viruses. Silica has an excellent biosafety profile and has been tested in several early phase clinical trials since 2012, demonstrating good tolerability and minimal reported side effects. In this review, we discuss the clinical development of silica nanoparticles to date and identify the gaps and potential pitfalls in its path to clinical translation.

Natural Biopolymers as Smart Coating Materials of Mesoporous Silica Nanoparticles for Drug Delivery

In recent years, the functionalization of mesoporous silica nanoparticles (MSNs) with different types of responsive pore gatekeepers have shown great potential for the formulation of drug delivery systems (DDS) with minimal premature leakage and site-specific controlled release. New nanotechnological approaches have been developed with the objective of utilizing natural biopolymers as smart materials in drug delivery applications. Natural biopolymers are sensitive to various physicochemical and biological stimuli and are endowed with intrinsic biodegradability, biocompatibility, and low immunogenicity. Their use as biocompatible smart coatings has extensively been investigated in the last few years. This review summarizes the MSNs coating procedures with natural polysaccharides and protein-based biopolymers, focusing on their application as responsive materials to endogenous stimuli. Biopolymer-coated MSNs, which conjugate the nanocarrier features of mesoporous silica with the biocompatibility and controlled delivery provided by natural coatings, have shown promising therapeutic outcomes and the potential to emerge as valuable candidates for the selective treatment of various diseases.

Novel Antitumor Agents Based on Fluorescent Benzofurazan Derivatives and Mesoporous Silica

Two novel fluorescent mesoporous silica-based hybrid materials were obtained through the covalent grafting of [4-hydrazinyl-7-nitrobenz-[2,1,3-d]-oxadiazole (NBDH) and N¹-(7-nitrobenzo[c][1,2,5]-oxadiazol-4-yl) benzene-1,2-diamine (NBD-PD), respectively, inside the channels of mesoporous silica SBA-15. The presence of fluorescent organic compounds (nitrobenzofurazan derivatives) was confirmed by infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), thermal analysis (TG), and fluorescence spectroscopy. The nitrogen physisorption analysis showed that the nitrobenzofurazan derivatives were distributed uniformly on the internal surface of SBA-15, the immobilization process having a negligible effect on the structure of the support. Their antioxidant activity was studied by measuring the ability to reduce free radicals DPPH (free radical scavenging activity), in order to formulate potential applications of the materials obtained. Cytotoxicity of the newly synthesized materials, SBA-NBDH and SBA-NBD-PD, was evaluated on human B16 melanoma cells. The morphology of these cells, internalization and localization of the investigated materials in melanoma and fibroblast cells were examined through fluorescence imaging. The viability of B16 (3D) spheroids after treatment with SBA-NBDH and SBA-NBD-PD was evaluated using MTS assay. The results showed that both materials induced a selective antiproliferative effect, reducing to various degrees the viability of melanoma cells. The observed effect was enhanced with increasing concentration. SBA-NBD-PD exhibited a higher antitumor effect compared to SBA-NBDH starting with a concentration of 125 µg/mL. In both cases, a significantly more pronounced antiproliferative effect on tumor cells compared to normal cells was observed. The viability of B16 spheroids dropped by 40% after treatment with SBA-NBDH and SBA-NBD-PD at 500 µg/mL concentration, indicating a clear cytotoxic effect of the tested compounds. These results suggest that both newly synthesized biomaterials could be promising antitumor agents for applications in cancer therapy.

Bioevaluation of magnetic mesoporous silica rods: cytotoxicity, cell uptake and biodistribution in zebrafish and rodents

Mesoporous silica nanoparticles (MSN) characterized by large surface area, pore volume, tunable chemistry, and biocompatibility have been widely studied in nanomedicine as imaging and therapeutic carriers. Most of these studies focused on spherical particles. In contrast, mesoporous silica rods (MSR) that are more challenging to prepare have been less investigated in terms of toxicity, cellular uptake, or biodistribution. Interestingly, previous studies showed that silica rods penetrate fibrous tissues or mucus layers more efficiently than their spherical counterparts. Recently, we reported the synthesis of MSR with distinct aspect ratios and validated their use in multiple imaging modalities by loading the pores with maghemite nanocrystals and functionalizing the silica surface with green and red fluorophores. Herein, based on an initial hypothesis of high liver accumulation of the MSR and a future vision that they could be used for early diagnosis or therapy in fibrotic liver diseases; the cytotoxicity and cellular uptake of MSR were assessed in zebrafish liver (ZFL) cells and the in vivo safety and biodistribution was investigated via fluorescence molecular imaging (FMI) and magnetic resonance imaging (MRI) employing zebrafish larvae and rodents. The selection of these animal models was prompted by the well-established fatty diet protocols inducing fibrotic liver in zebrafish or rodents that serve to investigate highly prevalent liver conditions such as non-alcoholic fatty liver disease (NAFLD). Our study demonstrated that magnetic MSR do not cause cytotoxicity in ZFL cells regardless of the rods' length and surface charge (for concentrations up to 50 μg ml-1, 6 h) and that MSR are taken up by the ZFL cells in large amounts despite their length of ∼1 μm. In zebrafish larvae, it was observed that they could be safely exposed to high MSR concentrations (up to 1 mg ml-1 for 96 h) and that the rods pass through the liver without causing toxicity. The high accumulation of MSR in rodents' livers at short post-injection times (20% of the administered dose) was confirmed by both FMI and MRI, highlighting the utility of the MSR for liver imaging by both techniques. Our results could open new avenues for the use of rod-shaped silica particles in the diagnosis of pathological liver conditions.

The role of imaging in targeted delivery of nanomedicine for cancer therapy

Nanomedicines overcome the pharmacokinetic limitations of traditional drug formulations and have promising prospect in cancer treatment. However, nanomedicine delivery in vivo is still facing challenges from the complex physiological environment. For the purpose of effective tumor therapy, they should be designed to guarantee the five features principle, including long blood circulation, efficient tumor accumulation, deep matrix penetration, enhanced cell internalization and accurate drug release. To ensure the excellent performance of the designed nanomedicine, it would be better to monitor the drug delivery process as well as the therapeutic effects by real-time imaging. In this review, we summarize strategies in developing nanomedicines for efficiently meeting the five features of drug delivery, and the role of several imaging modalities (fluorescent imaging (FL), magnetic resonance imaging (MRI), computed tomography (CT), photoacoustic imaging (PAI), positron emission tomography (PET), and electron microscopy) in tracing drug delivery and therapeutic effect in vivo based on five features principle.

Recent advances in mesoporous silica nanoparticle-based targeted drug-delivery systems for cancer therapy

Targeted drug-delivery systems are a growing research topic in tumor treatment. In recent years, mesoporous silica nanoparticles (MSNs) have been extensively studied and applied in noninvasive and biocompatible drug-delivery systems for tumor therapy due to their outstanding advantages, which include high surface area, large pore volume, tunable pore size, easy surface modification and stable framework. The advances in the application of MSNs for anticancer drug targeting are covered and highlighted in this review, and the challenges and prospects of MSN-based targeted drug-delivery systems are discussed. This review provides new insights for researchers interested in targeted drug-delivery systems against cancer.

M. de Rosales R, Da Silva I, Sobilo J, Lerondel S, Tóth É, Djanashvili K. On the Versatility of Nanozeolite Linde Type L for Biomedical Applications: Zirconium-89 Radiolabeling and In Vivo Positron Emission Tomography Study

Porous materials, such as zeolites, have great potential for biomedical applications, thanks to their ability to accommodate positively charged metal-ions and their facile surface functionalization. Although the latter aspect is important to endow the nanoparticles with chemical/colloidal stability and desired biological properties, the possibility for simple ion-exchange enables easy switching between imaging modalities and/or combination with therapy, depending on the envisioned application. In this study, the nanozeolite Linde type L (LTL) with already confirmed magnetic resonance imaging properties, generated by the paramagnetic gadolinium (GdIII) in the inner cavities, was successfully radiolabeled with a positron emission tomography (PET)-tracer zirconium-89 (89Zr). Thereby, exploiting 89Zr-chloride resulted in a slightly higher radiolabeling in the inner cavities compared to the commonly used 89Zr-oxalate, which apparently remained on the surface of LTL. Intravenous injection of PEGylated 89Zr/GdIII-LTL in healthy mice allowed for PET-computed tomography evaluation, revealing initial lung uptake followed by gradual migration of LTL to the liver and spleen. Ex vivo biodistribution confirmed the in vivo stability and integrity of the proposed multimodal probe by demonstrating the original metal/Si ratio being preserved in the organs. These findings reveal beneficial biological behavior of the nanozeolite LTL and hence open the door for follow-up theranostic studies by exploiting the immense variety of metal-based radioisotopes.

Engineering mesoporous silica nanoparticles for drug delivery: where are we after two decades?

The present review details a chronological description of the events that took place during the development of mesoporous materials, their different synthetic routes and their use as drug delivery systems. The outstanding textural properties of these materials quickly inspired their translation to the nanoscale dimension leading to mesoporous silica nanoparticles (MSNs). The different aspects of introducing pharmaceutical agents into the pores of these nanocarriers, together with their possible biodistribution and clearance routes, would be described here. The development of smart nanocarriers that are able to release a high local concentration of the therapeutic cargo on-demand after the application of certain stimuli would be reviewed here, together with their ability to deliver the therapeutic cargo to precise locations in the body. The huge progress in the design and development of MSNs for biomedical applications, including the potential treatment of different diseases, during the last 20 years will be collated here, together with the required work that still needs to be done to achieve the clinical translation of these materials. This review was conceived to stand out from past reports since it aims to tell the story of the development of mesoporous materials and their use as drug delivery systems by some of the story makers, who could be considered to be among the pioneers in this area.

End-Sealing of Peptide Nanotubes by Cationic Amphiphilic Polypeptides and Their Salt-Responsive Accordion-like Opening and Closing Behavior

One strategy to prepare phase-separated co-assembly is to use the existing assembly as a platform to architect structures. For this purpose, the edge of a sheet or tube-shaped molecular assembly, which is less hydrophilic than the bulk region can become a starting point to build assembly units to realize more complex structures. In this study, we succeeded in preparing rod-shaped nanocapsules with previously unachieved sealing efficiency (>99%) by fine-tuning the properties of cationic amphiphilic polypeptides to seal the ends of neutral charge nanotubes. In addition, we demonstrated the nanocapsule's reversible responsiveness to salt. In high salt concentrations, a decrease in electrostatic repulsion between cationic polypeptides caused tearing and shrinking of the nanocapsule's sealing dome, which resulted in an opened nanotube. On the other hand, when salt was removed, the electrostatic repulsion among the cationic peptides localizing on the edge of opened nanocapsules was recovered, and the sealing membrane swelled up like an accordion to create a distance between the peptides, resulting in the restoration of the seal.

Integrative Metabolomics, Proteomics and Transcriptomics Analysis Reveals Liver Toxicity of Mesoporous Silica Nanoparticles

As pharmaceutical excipients, mesoporous silica nanoparticles (MSNs) have attracted considerable concern based on potential risks to the public. The impact of MSNs on biochemical metabolism is poorly understood, and few studies have compared the effects of MSNs administered via different routes. To evaluate the hepatotoxicity of MSNs, metabolomics, proteomics and transcriptomic analyses were performed in mice after intravenous (20 mg/kg/d) or oral ad-ministration (200 mg/kg/d) of MSNs for 10 days. Intravenous injection induced significant hepatic injury based on pathological inspection and increased the levels of AST/ALT and the inflammatory factors IL-6, IL-1β and TNF-a. Omics data suggested intravenous administration of MSNs perturbed the following metabolites: succinate, hypoxanthine, GSSG, NADP+, NADPH and 6-phosphogluconic acid. In addition, increases in GPX, SOD3, G6PD, HK, and PFK at proteomic and transcriptomic levels suggested elevation of glycolysis and pentose phosphate pathway, synthesis of glutathione and nucleotides, and antioxidative pathway activity, whereas oxidative phosphorylation, TCA and mitochondrial energy metabolism were reduced. On the other hand, oral administration of MSNs disturbed inflammatory factors and metabolites of ribose-5-phosphate, 6-phosphogluconate, GSSG, and NADP+ associated with the pentose phosphate pathway, glutathione synthesis and oxidative stress albeit to a lesser extent than intravenous injection despite the administration of a ten-fold greater dose. Overall, systematic biological data suggested that intravenous injection of nanoparticles of pharmaceutical excipients substantially affected hepatic metabolism function and induced oxidative stress and inflammation, whereas oral administration exhibited milder effects compared with intravenous injection.

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.

Biocompatible N-acetyl-nanoconstruct alleviates lipopolysaccharide-induced acute lung injury in vivo

Oxidative stress plays important roles in inflammatory responses during acute lung injury (ALI). Recently, nanoconstruct (Nano)-based drug-delivery systems have shown promise in many models of inflammation. In this study, we evaluated the anti-inflammatory effects of N-acetylcysteine (NAC) loaded in a biocompatible Nano using a rat model of ALI. We synthesized a Nano with a good NAC-releasing capacity using porous silica Nano, which was used to produce Nano/NAC complexes. For in vivo experiments, Sprague–Dawley rats were intraperitoneally administered NAC or Nano/NAC 30 min after intratracheal instillation of lipopolysaccharide. After 6 h, bronchoalveolar lavage fluids and lung tissues were collected. The anti-oxidative effect of the Nano/NAC complex was confirmed by demonstrating reduced levels of reactive oxygen species after treatment with the Nano/NAC in vitro. In vivo experiments also showed that the Nano/NAC treatment may protect against LPS‐induced ALI thorough anti‐oxidative and anti‐inflammatory effects, which may be attributed to the inactivation of the NF‐κB and MAPK pathways. In addition, the effects of Nano/NAC treatment were shown to be superior to those of NAC alone. We suggest the therapeutic potential of Nano/NAC treatment as an anti‐inflammatory agent against ALI. Furthermore, our study can provide basic data for developing nanotechnology-based pharmacotherapeutics for ALI.

Chitosan oligosaccharide modified liposomes enhance lung cancer delivery of paclitaxel

Lung cancer is one of the leading causes of cancer-related death worldwide. Various therapeutic failed in the effective treatment of the lung cancer due to their limited accumulation and exposure in tumors. In order to promote the chemotherapeutics delivery to lung tumor, we introduced chitosan oligosaccharide (CSO) modification on the liposomes. CSO conjugated Pluronic P123 polymers with different CSO grafting amounts, called as CP50 and CP20, were synthesized and used to prepare CSO modified liposomes (CP50-LSs and CP20-LSs). CP50-LSs and CP20-LSs displayed significantly enhanced cellular uptake in A549 cells in vitro as well as superior tumor accumulation in vivo compared with non-CSO modified liposomes (P-LSs). This phenomenon was related to the increased affinity between CSO modified liposomes and tumor cells following massive adsorption of collagen, which was highly expressed in lung tumors. In the A549 tumor-bearing mouse model, intravenous injection of paclitaxel (PTX)-loaded CP50-LSs every 3 days for 21 days resulted in optimal antitumor therapeutic performance with an inhibition rate of 86.4%. These results reveal that CSO modification provides promising applicability for nanomedicine design in the lung cancer treatment.

Biosafety of mesoporous silica nanoparticles: a combined experimental and literature study

Mesoporous silica (MS) particles have been explored for various healthcare applications, but universal data about their safety and/or toxicity are yet to be well-established for clinical purposes. Information about general toxicity of hollow MS (HMS) particles and about immunotoxicity of MS particles are significantly lacked. Therefore, acute toxicity and immunotoxicity of HMS particles were experimentally evaluated. A systematic and objective literature study was parallelly performed to analyze the published in vivo toxicity of MS particles. Lethal acute toxicity of MS particles is likely to arise from their physical action after intravenous and intraperitoneal administrations, and only rarely observed after subcutaneous administration. No clear relationship was identified between physicochemical properties of MS particles and lethality as well as maximum tolerated dose with some exceptions. At sub-lethal doses, MS particles tend to accumulate mainly in lung, liver, and spleen. The HMS particles showed lower inflammation-inducing ability than polyinosinic-polycytidylic acid and almost the same allergy-inducing ability as Alum. Finally, the universal lowest observed adverse effect levels were determined as 0.45, 0.81, and 4.1 mg/kg (human equivalent dose) for intravenous, intraperitoneal, and subcutaneous administration of MS particles, respectively. These results could be helpful for determining an appropriate MS particle dose in clinical study.

Targeted-lung delivery of dexamethasone using gated mesoporous silica nanoparticles. A new therapeutic approach for acute lung injury treatment

Acute lung injury (ALI) is a critical inflammatory syndrome, characterized by increased diffuse inflammation and severe lung damage, which represents a clinical concern due to the high morbidity and mortality in critical patients. In last years, there has been a need to develop more effective treatments for ALI, and targeted drug delivery to inflamed lungs has become an attractive research field. Here, we present a nanodevice based on mesoporous silica nanoparticles loaded with dexamethasone (a glucocorticoid extensively used for ALI treatment) and capped with a peptide that targets the TNFR1 receptor expressed in pro-inflammatory macrophages (TNFR-Dex-MSNs) and avoids cargo leakage. TNFR-Dex-MSNs nanoparticles are preferentially internalized by pro-inflammatory macrophages, which overexpressed the TNFR1 receptor, with the subsequent cargo release upon the enzymatic hydrolysis of the capping peptide in lysosomes. Moreover, TNFR-Dex-MSNs are able to reduce the levels of TNF-α and IL-1β cytokines in activated pro-inflammatory M1 macrophages. The anti-inflammatory effect of TNFR-Dex-MSNs is also tested in an in vivo ALI mice model. The administered nanodevice (intravenously by tail vein injection) accumulated in the injured lungs and the controlled dexamethasone release reduces markedly the inflammatory response (TNF-α IL-6 and IL-1β levels). The attenuation in lung damage, after treatment with TNFR-Dex-MSNs, is also confirmed by histopathological studies. Besides, the targeted-lung dexamethasone delivery results in a decrease of dexamethasone derived side-effects, suggesting that targeted nanoparticles can be used for therapy in ALI and could help to overcome the clinical limitations of current treatments.

An Update on Mesoporous Silica Nanoparticle Applications in Nanomedicine

The efficient and safe delivery of therapeutic drugs, proteins, and nucleic acids are essential for meaningful therapeutic benefits. The field of nanomedicine shows promising implications in the development of therapeutics by delivering diagnostic and therapeutic compounds. Nanomedicine development has led to significant advances in the design and engineering of nanocarrier systems with supra-molecular structures. Smart mesoporous silica nanoparticles (MSNs), with excellent biocompatibility, tunable physicochemical properties, and site-specific functionalization, offer efficient and high loading capacity as well as robust and targeted delivery of a variety of payloads in a controlled fashion. Such unique nanocarriers should have great potential for challenging biomedical applications, such as tissue engineering, bioimaging techniques, stem cell research, and cancer therapies. However, in vivo applications of these nanocarriers should be further validated before clinical translation. To this end, this review begins with a brief introduction of MSNs properties, targeted drug delivery, and controlled release with a particular emphasis on their most recent diagnostic and therapeutic applications.

Cytotoxicity of mesoporous silica modified by amino and carboxyl groups on vascular endothelial cells

Mesoporous silica is widely used because of its unique and excellent properties, especially it can be used as a drug carrier and gene carrier in the biomedical field. After the mesoporous silica is put into clinical use, it is more likely to be exposed in human body. Therefore, the effect of mesoporous silica on human body cannot be ignored. The injury of vascular endothelial cells is a prerequisite for the occurrence of many cardiovascular diseases. As a drug and gene carrier, mesoporous silica increases its contact with vascular endothelial cells, so its toxic effect on cardiovascular system cannot be ignored. In this study, amino (NH₂ ) and carboxyl (COOH) were modified on mesoporous silica SBA-15 by post-grafting. The results showed that it still maintained the one-dimensional hexagonal mesoporous structure of SBA-15 and had typical mesoporous structure. Then human umbilical vein endothelial cells (HUVECs) were infected with SBA-15, NH₂ -SBA-15, and COOH-SBA-15. The results showed that the functionalized mesoporous silica SBA-15 had cytotoxicity to HUVECs and damaged the cell membrane, but compared with the unmodified mesoporous silica SBA-15 the cytotoxicity of functionalized mesoporous silica SBA-15 was lower and the toxicity of carboxyl modified group was the lowest. By comparing the cell inhibition rate and the expression level of lactate dehydrogenate and reactive oxygen species induced by the three materials, oxidative damage and cell membrane damage may be two mechanisms of cytotoxicity. Mesoporous silica SBA-15 has an effect on cardiovascular system by inducing the high expression of nitric oxide, intercellular adhesive molecule-1 and vascular cell adhesive molecule-1 in HUVECs. In summary, our results show that mesoporous silica is toxic to vascular endothelial cells.

Biomedical application of mesoporous silica nanoparticles as delivery systems: a biological safety perspective

The application of mesoporous silica nanoparticles (MSNs) as drug delivery systems to deliver drugs, proteins, and genes has expanded considerably in recent years, using in vitro and animal studies. For future translation to clinical applications, the biological safety aspects of MSNs must be considered carefully. This paper reviews the biosafety of MSNs, examining key issues such as biocompatibility, effects on immune cells and erythrocytes, biodistribution, biodegradation and clearance, and how these vary depending on the effects of the physical and chemical properties of MSNs such as particle size, porosity, morphology, surface charge, and chemical modifications. The future use of MSNs as a delivery system must extend beyond what has been learnt thus far using rodent animal models to encompass larger animals.

Adverse effects of amorphous silica nanoparticles: Focus on human cardiovascular health

Amorphous silica nanoparticle (SiNPs) has tremendous potential for a host of applications, while its mass production, broad application and environmental release inevitably increase the risk of human exposure. SiNPs could enter into the human body through different routes such as inhalation, ingestion, skin contact and even injection for medical applications. The cardiovascular system is gradually recognized as one of the primary sites for engineered NPs exerting adverse effects. Accumulating epidemiological or experimental evidence support the association between SiNPs exposure and adverse cardiovascular effects. However, this topic is still in its infancy, and the literature shows high inter-study variability and even contradictory results. New challenges still present in the safety evaluation of SiNPs, and its toxicological mechanisms are poorly understood. Here, scientific papers related to cardiovascular studies of SiNPs in vivo and in vitro were selected, and the updated particle-caused cardiovascular toxicity and potential mechanisms were summarized. Moreover, the understanding of how factors primarily including exposure dose, route of administration, particle size and surface properties, influence the interaction between SiNPs and cardiovascular system was discussed. In particular, the adverse outcome pathway (AOP) framework by which SiNPs cause deleterious effects in the cardiovascular system was described, aiming to provide useful information necessary for the regulatory decision and to guide a safer application of nanotechnology.

Global Proteomics to Study Silica Nanoparticle-Induced Cytotoxicity and Its Mechanisms in HepG2 Cells

Silica nanoparticles (SiO₂ NPs) are commonly used in medical and pharmaceutical fields. Research into the cytotoxicity and overall proteomic changes occurring during initial exposure to SiO₂ NPs is limited. We investigated the mechanism of toxicity in human liver cells according to exposure time [0, 4, 10, and 16 h (h)] to SiO₂ NPs through proteomic analysis using mass spectrometry. SiO₂ NP-induced cytotoxicity through various pathways in HepG2 cells. Interestingly, when cells were exposed to SiO₂ NPs for 4 h, the morphology of the cells remained intact, while the expression of proteins involved in mRNA splicing, cell cycle, and mitochondrial function was significantly downregulated. These results show that the toxicity of the nanoparticles affects protein expression even if there is no change in cell morphology at the beginning of exposure to SiO₂ NPs. The levels of reactive oxygen species changed significantly after 10 h of exposure to SiO₂ NPs, and the expression of proteins associated with oxidative phosphorylation, as well as the immune system, was upregulated. Eventually, these changes in protein expression induced HepG2 cell death. This study provides insights into cytotoxicity evaluation at early stages of exposure to SiO₂ NPs through in vitro experiments.

Short-Term Oral Administration of Mesoporous Silica Nanoparticles Potentially Induced Colon Inflammation in Rats Through Alteration of Gut Microbiota

PURPOSE

Mesoporous silica (MSNs) have attracted considerable attention for its application in the field of drug delivery and biomedicine due to its high surface area, large pore volume, and low toxicity. Recently, numerous studies revealed that gut microbiota is of critical relevance to host health. However, the toxicological studies of MSNs were mainly based on the degradation, biodistribution, and excretion in mammalian after oral administration for now. Here in this study, we explored the impacts of oral administration of three kinds of MSNs on gut microbiota in rats to assess its potential toxicity.

METHODS

Forty rats were divided into four groups: control group; Mobil Composition of Matter No. 41 type mesoporous silica (MCM-41) group; Santa Barbara Amorphous-15 type mesoporous silica (SBA-15) group, and biodegradable dendritic center-radial mesoporous silica nanoparticle (DMSN) group. Fecal samples were collected 3 days and 7 days after the intake of MSNs and analyzed with high throughput sequencing. Gastric tissues in rats were obtained after dissection for the histological study.

RESULTS

Three different MSNs (MCM-41, SBA-15, and DMSN) were successfully prepared in this study. The pore size of three MSNs was calculated similarly as (3.54 ± 0.15) nm, (3.48 ± 0.21) nm, and (3.45 ± 0.17) nm according to the BET & BJH model, respectively, while the particle size of MCM-41, SBA-15 and DMSN was around 209.2 nm, 1349.56 nm, and 244.4 nm, respectively. In the gene analysis of 16S rRNA, no significant changes in the diversity and richness were found between groups, while Verrucomicrobia decreased and Candidatus Saccharibacteria increased in MCM-41 treated groups. Meanwhile, no inflammatory and erosion symptoms were observed in the morphological analysis of the colons, except the MCM-41 treated group.

CONCLUSION

Three different MSNs, MCM-41, SBA-15, and DMSN were successfully prepared, and this study firstly suggested the impact of MSNs on the gut microbiota, and further revealing the potential pro-inflammatory effects of oral administration of MCM-41 was possibly through the changing of gut microbiota.

Delivery of Natural Agents by Means of Mesoporous Silica Nanospheres as a Promising Anticancer Strategy

Natural prodrugs derived from different natural origins (e.g., medicinal plants, microbes, animals) have a long history in traditional medicine. They exhibit a broad range of pharmacological activities, including anticancer effects in vitro and in vivo. They have potential as safe, cost-effective treatments with few side effects, but are lacking in solubility, bioavailability, specific targeting and have short half-lives. These are barriers to clinical application. Nanomedicine has the potential to offer solutions to circumvent these limitations and allow the use of natural pro-drugs in cancer therapy. Mesoporous silica nanoparticles (MSNs) of various morphology have attracted considerable attention in the search for targeted drug delivery systems. MSNs are characterized by chemical stability, easy synthesis and functionalization, large surface area, tunable pore sizes and volumes, good biocompatibility, controlled drug release under different conditions, and high drug-loading capacity, enabling multifunctional purposes. In vivo pre-clinical evaluations, a significant majority of results indicate the safety profile of MSNs if they are synthesized in an optimized way. Here, we present an overview of synthesis methods, possible surface functionalization, cellular uptake, biodistribution, toxicity, loading strategies, delivery designs with controlled release, and cancer targeting and discuss the future of anticancer nanotechnology-based natural prodrug delivery systems.

Characterization of the Biodistribution of a Silica Vesicle Nanovaccine Carrying a Rhipicephalus (Boophilus) microplus Protective Antigen With in vivo Live Animal Imaging

Development of veterinary subunit vaccines comes with a spectrum of challenges, such as the choice of adjuvant, antigen delivery vehicle, and optimization of dosing strategy. Over the years, our laboratory has largely focused on investigating silica vesicles (SVs) for developing effective veterinary vaccines for multiple targets. Rhipicephalus microplus (cattle tick) are known to have a high impact on cattle health and the livestock industry in the tropical and subtropical regions. Development of vaccine using Bm86 antigen against R. microplus has emerged as an attractive alternative to control ticks. In this study, we have investigated the biodistribution of SV in a live animal model, as well as further explored the SV ability for vaccine development. Rhodamine-labeled SV-140-C₁₈ (Rho-SV-140-C₁₈) vesicles were used to adsorb the Cy5-labeled R. microplus Bm86 antigen (Cy5-Bm86) to enable detection and characterization of the biodistribution of SV as well as antigen in vivo in a small animal model for up to 28 days using optical fluorescence imaging. We tracked the in vivo biodistribution of SVs and Bm86 antigen at different timepoints (days 3, 8, 13, and 28) in BALB/c mice. The biodistribution analysis by live imaging as well as by measuring the fluorescent intensity of harvested organs over the duration of the experiment (28 days) showed greater accumulation of SVs at the site of injection. The Bm86 antigen biodistribution was traced in lymph nodes, kidney, and liver, contributing to our understanding how this delivery platform successfully elicits antibody responses in the groups administered antigen in combination with SV. Selected tissues (skin, lymph nodes, spleen, kidney, liver, and lungs) were examined for any cellular abnormalities by histological analysis. No adverse effect or any other abnormalities were observed in the tissues.

Microwave assisted synthesis of Fe3O4 stabilized ZrO2 nanoparticles - Free radical scavenging, radiolabeling and biodistribution in rabbits

AIMS

In vivo biodistribution of radio labeled ZrO₂ nanoparticles is addressed for better imaging, therapy and diagnosis. Nanoparticles are synthesized by microwave assisted sol-gel technique using Fe₃O₄ as a stabilizer. Antioxidant assay, hemolytic activity in human blood and biodistribution in rabbits was explored to study the therapeutical as well as in vivo targeted diagnostic applications of as synthesized nanoparticles.

MAIN METHODS

Fe₃O₄ stabilized zirconia nanoparticles are synthesized using microwave assisted sol-gel method. Microwave (MW) powers are varied in the range of 100 to 1000 W. As synthesized nanoparticles are evaluated using different characterizations such as X-ray diffractometer, scanning electron microscope, Raman spectroscopy, impedance analyzer, Vickers micro hardness indenter, FTIR, and UV-Vis spectroscopy. In vitro activity of synthesized nanoparticles is checked in freshly extracted human blood serum. To study biodistribution of Fe₃O₄ stabilized zirconia nanoparticles in rabbit, technetium-99 m was used for labeling purpose. The labeling efficacy and stability of labeled nanoparticles are also measured with instant thin layer chromatography (ITLC) method. Intravenous injection of ^99mTc-Fe₃O₄ stabilized zirconia nanoparticles (0.2 ml), containing 110 MBq of radioactivity, is performed to study the biodistribution; nanoparticles are injected into the ear vein of animal (rabbit).

KEY FINDINGS

Zirconia (ZrO₂) nanoparticles (NPs) are stabilized using Fe₃O₄ that were prepared by means of microwave assisted sol-gel method. Crystallite size (~20 nm) agrees well with the values required to stabilize tetragonal zirconia (t-ZrO₂). Volume shrinkage results in high value of hardness (~1369). Dielectric constant values, compatible for biomedical application, are observed for tetragonally stabilized samples. Low value of hemolytic response is observed for Fe₃O₄ stabilized ZrO₂ NPs. ^99mTc radio labeled ZrO₂ NPs proved to be potential candidate to study biodistribution. Biodistribution studies show stability of radiolabeled NPs in the original suspension as well as in blood serum. CT scan of rabbit is performed for several times to check the biodistribution of NPs with time and survival of rabbit. Results suggest that these NPs can also be used as targeted nanoparticles as well as variants of drug payload carrier.

SIGNIFICANCE

Results signify that Fe₃O₄ stabilized ZrO₂ nanoparticles synthesized by microwave assisted sol-gel method may be considered as "all-rounder" nanoplatform and are safe enough to be used in diagnostic as well as therapeutic purposes.

Distinct Proteins in Protein Corona of Nanoparticles Represent a Promising Venue for Endogenous Targeting - Part II: In vitro and in vivo Kinetics Study

Introduction

Nanoparticles (NPs), upon introduction to the biological systems, become wrapped by serum and cellular proteins constituting the protein corona (PC). This PC contributes largely to the NPs’ interaction with the biological systems and their subsequent functions. On the one hand, PC can decrease the efficiency of targeting by directing the NPs to the reticuloendothelial system (RES) or by masking the active targeting moieties and decreasing their ability to bind to their target receptors. On the other hand, some components of PC have offered hopes for achieving endogenous targeting.

Methods

In this study, we aimed at the investigation of the role of the PC in determining the behavior of cRGDyk peptide-unconjugated and -conjugated NPs (uNPs and cNPs) exhibiting different physicochemical properties and their interaction with melanoma on in vitro and in vivo levels. Mathematical modeling has been utilized to understand the kinetics of the interaction of NPs with the tumor cells and different organs, respectively.

Results

Endocytosis and exocytosis were reported to occur simultaneously for the utilized NPs. The balance was largely dependent on the NPs’ physicochemical properties and the role of the PC. In addition, distinct proteins present in the PC (illustrated in the results of the PC analysis in part I) have also determined the patterns of the NPs’ distribution in different organs and tissues of the vascular system, the RES system and the target tumot tissue. Vitronectin (VN) was found to mediate higher accumulation in integrin receptor-expressing melanoma cells, while complement 3 protein (C3) and clusterin (CLU), as an opsonin and dysopsonin, respectively, regulated the balance between the RES uptake and blood circulation.

Discussion

PC, if properly modulated by tuning NPs’ physicochemical properties, can serve as a potential venue for optimum utilization of NPs in cancer therapy.

Ladder-like targeted and gated doxorubicin delivery using bivalent aptamer in vitro and in vivo

Regarding side effects of commonly used chemotherapeutic drugs on normal tissues, researchers introduced smart delivery and on-demand release systems. Herein, we applied a bivalent aptamer composed of ATP and AS1411 aptamers for separate targeting and gating of mesoporous silica nanoparticles in a ladder like structure with one bifunctional molecule. First part of the apatmer, AS1411, direct the delivery system to the desired site while the second part, ATP aptamer, opens the pores and release the drug just after penetrance to the cytoplasm ensuring delivery of DOX into the tumor cells. This approach faced the previous challenge of coincident targeting and gating with one aptamer. Our results demonstrated that the proposed nano-system remarkably accumulated in cancer tissue and released the drug in a sustained pattern in cancer cells. It was notably effective for inducing apoptosis in cancer cells and tumor growth inhibition without any significant side effect on normal cells and organs. Moreover, Si-cs-DOX-AAapt improved the mice survival time compared with free doxorubicin and there was no significant change in weight of mice administered with the targeted formulation. This report may open new insight for providing smart delivery systems for successful cancer treatment by introducing separate gating and targeting property by a bivalent aptamer to increase the control over drug release.

Targeted rod-shaped mesoporous silica nanoparticles for the co-delivery of camptothecin and survivin shRNA in to colon adenocarcinoma in vitro and in vivo

Simultaneous drug and gene delivery to cancer cells has been introduced to provide advantages of the synergistic effects of gene to sensitize the cancer cells to chemotherapeutic agent. In the current study, nucleolin-targeted co-delivery system, based on PEGylated rod-shaped mesoporous silica NPs was developed as a biocompatible nanocarrier for simultaneous delivery of camptothecin and survivin shRNA-expressing plasmid (iSur-DNA) to colon adenocarcinoma. The structural characterization including hydrodynamic radius and morphological characteristics of the prepared system demonstrated the mesoporous rod-shaped structure of the prepared system with 100-150 nm diameter. Camptothecin was loaded into the rod-shaped MSN NPs with encapsulation efficiency of 32%. At the next stage, the prepared camptothecin-loaded system was PEGylated and then iSur-DNA was condensed with C/P ratio of 6 to form PEG@MSNR-CPT/Sur. Then, the prepared camptothecin-iSur-DNA loaded PEGylated rod-shaped mesoporous silica NPs were tagged with AS1411 DNA aptamer (Apt-PEG@MSNR-CPT/Sur) in order to provide selective therapy against colorectal adenocarcinoma. The obtained results showed that the prepared platform controlled the release of anticancer drug, camptothecin. The experimental results indicated potent synergistic effect of iSur-pDNA and CPT in in vitro cytotoxicity, apoptosis induction and in vivo antitumor effect. In addition, tagging the system with AS1411 DNA aptamer facilitated drug uptake into nucleolin positive colorectal cancer cells leading to higher cellular toxicity and apoptosis induction in C26 cells compared to nucleolin-negative CHO cell line. Apt-PEG@MSNR-CPT/Sur system significantly supressed tumor growth rate in C26 tumor bearing mice while improving survival rate and pharmacokinetics of the platform in comparison with PEG@MSNR-CPT and PEG@MSNR-CPT/Sur. It could be concluded that the developed nucelolin targeted nanomedicine for co-delivery of camptothecin and iSur-DNA could serve as a versatile nanotherapeutic system against colorectal cancer.

Tracing the In Vivo Fate of Nanoparticles with a "Non-Self" Biological Identity

Nanoparticles can acquire a biomolecular corona with a species-specific biological identity. However, "non-self" incompatibility of recipient biological systems is often not considered, for example, when rodents are used as a model organism for preclinical studies of biomolecule-inspired nanomedicines. Using zebrafish embryos as an emerging model for nanobioimaging, here we unravel the in vivo fate of intravenously injected 70 nm SiO₂ nanoparticles with a protein corona preformed from fetal bovine serum (FBS), representing a non-self biological identity. Strikingly rapid sequestration and endolysosomal acidification of nanoparticles with the preformed FBS corona were observed in scavenger endothelial cells within minutes after injection. This led to loss of blood vessel integrity and to inflammatory activation of macrophages over the course of several hours. As unmodified nanoparticles or the equivalent dose of FBS proteins alone failed to induce the observed pathophysiology, this signifies how the corona enriched with a differential repertoire of proteins can determine the fate of the nanoparticles in vivo. Our findings thus reveal the adverse outcome triggered by incompatible protein coronas and indicate a potential pitfall in the use of mismatched species combinations during nanomedicine development.

Silica-Based Nanoparticles for Biomedical Applications: From Nanocarriers to Biomodulators

Silica-based nanoparticles (SNPs) are a classic type of material employed in biomedical applications because of their excellent biocompatibility and tailorable physiochemical properties. Typically, SNPs are designed as nanocarriers for therapeutics delivery, which can address a number of intrinsic drawbacks of therapeutics, including limited bioavailability, short circulation lifetime, and unfavorable biodistribution. To improve the delivery efficiency and spatiotemporal precision, tremendous efforts have been devoted to engineering the physiochemical properties of SNPs, including particle size, morphology, and mesostructure, as well as conjugating targeting ligands and/or "gatekeepers" to endow improved cell selectivity and on demand release profiles. Despite significant progress, the biologically inert nature of the bare silica framework has largely restricted the functionalities of SNPs, rendering conventional SNPs mainly as nanocarriers for targeted delivery and controlled release. To meet the requirements of next generation nanomedicines with improved efficacy and precision, new insights on the relationship between the physiochemical properties of SNPs and their biological behavior are highly valuable. Meanwhile, a conceptual shift from a simple spatiotemporal control mechanism to a more sophisticated biochemistry and signaling pathway modulation would be of great importance.In this Account, an overview of our recent contribution to the field is presented, wherein SNPs with rationally designed nanostructures and nanochemistry are applied as nanocarriers (defined as "nanomaterials being used as a transport module for another substance" according to Wikipedia) and/or biomodulators (defined as "any material that modifies a biological response" according to Wiktionary). This Account encompasses two main sections. In the first section, we focus on the conventional nanocarriers concept with new insights on the design principles of the nanostructures. We present examples to demonstrate the engineering of pore geometry, surface topology, and asymmetry of nanoparticles to achieve enhanced drug, gene, and protein delivery efficiency. The contribution of surface roughness of SNPs on improving the cellular uptake efficiency, adhesion property, and DNA transfection capacity is particularly highlighted. In the second section, we discuss novel SNPs designed as biomodulators to regulate intracellular microenvironment and cell signaling, such as the oxidative stress and glutathione levels for improving the anticancer efficacy of therapeutics and mRNA transfection in specific cell lines. The interplay between the nanoparticles, biological system, and drugs is discussed. We further discuss how to engineer the composition of SNPs to modulate metal hemostasis to realize inherent anticancer activity. Two typical examples, including modulating copper signaling for tumor vasculature targeted therapy and controlling iron signaling for macrophage polarization based immunotherapy, are presented to highlight the unique advantages of SNPs as nanosized therapeutics in comparison to molecular drugs. Moreover, utilizing these two examples, we showcase the possibility of designing SNPs with intrinsic pharmaceutical activity to indirectly control tumor growth without inducing significant cytotoxicity, thus alleviating the biosafety concerns of nanomedicines. At the end of this Account, we discuss our personal perspectives on the promises, opportunities, and issues in engineered SNPs as nanocarriers as well as their transition toward biomodulators. With a major focus on the latter scenario, the current status and possible future directions are outlined.

One-year chronic toxicity evaluation of single dose intravenously administered silica nanoparticles in mice and their Ex vivo human hemocompatibility

Chronic toxicity evaluations of nanotechnology-based drugs are essential to support initiation of clinical trials. Ideally such evaluations should address the dosing strategy in human applications and provide sufficient information for long-term usage. Herein, we investigated one-year toxicity of non-surface modified silica nanoparticles (SNPs) with variations in size and porosity (Stöber SNPs 46 ± 4.9 and 432.0 ± 18.7 nm and mesoporous SNPs 466.0 ± 86.0 nm) upon single dose intravenous administration to female and male BALB/c mice (10 animal/sex/group) along with their human blood compatibility. Our evidence of clinical observation and blood parameters showed no significant changes in body weight, cell blood count, nor plasma biomarker indices. No significant changes were noted in post necropsy examination of internal organs and organ-to-body weight ratio. However, microscopic examination revealed significant amount of liver inflammation and aggregates of histocytes with neutrophils within the spleen suggesting an ongoing or resolving injury. The fast accumulation of these plain SNPs in the liver and spleen upon IV administration and the duration needed for their clearance caused these injuries. There were also subtle changes which were attributed to prior infarctions or resolved intravascular thrombosis and included calcifications in pulmonary vessels, focal cardiac fibrosis with calcifications, and focal renal injury. Most of the pathologic lesions were observed when large, non-porous SNPs were administered. Statistically significant chronic toxicity was not observed for the small non-porous particles and for the mesoporous particles. This one-year post-exposure evaluation indicate that female and male BALB/c mice need up to one year to recover from acute tissue toxic effects of silica nanoparticles upon single dose intravenous administration at their 10-day maximum tolerated dose. Further, ex vivo testing with human blood and plasma revealed no hemolysis or complement activation following incubation with these silica nanoparticles. These results can inform the potential utility of silica nanoparticles in biomedical applications such as controlled drug delivery where intravenous injection of the particles is intended.

Multimodal Decorations of Mesoporous Silica Nanoparticles for Improved Cancer Therapy

The presence of leaky vasculature and the lack of lymphatic drainage of small structures by the solid tumors formulate nanoparticles as promising delivery vehicles in cancer therapy. In particular, among various nanoparticles, the mesoporous silica nanoparticles (MSN) exhibit numerous outstanding features, including mechanical thermal and chemical stability, huge surface area and ordered porous interior to store different anti-cancer therapeutics with high loading capacity and tunable release mechanisms. Furthermore, one can easily decorate the surface of MSN by attaching ligands for active targeting specifically to the cancer region exploiting overexpressed receptors. The controlled release of drugs to the disease site without any leakage to healthy tissues can be achieved by employing environment responsive gatekeepers for the end-capping of MSN. To achieve precise cancer chemotherapy, the most desired delivery system should possess high loading efficiency, site-specificity and capacity of controlled release. In this review we will focus on multimodal decorations of MSN, which is the most demanding ongoing approach related to MSN application in cancer therapy. Herein, we will report about the recently tried efforts for multimodal modifications of MSN, exploiting both the active targeting and stimuli responsive behavior simultaneously, along with individual targeted delivery and stimuli responsive cancer therapy using MSN.

Targeting of Hepatic Macrophages by Therapeutic Nanoparticles

Hepatic macrophage populations include different types of cells with plastic properties that can differentiate into diverse phenotypes to modulate their properties in response to different stimuli. They often regulate the activity of other cells and play an important role in many hepatic diseases. In response to those pathological situations, they are activated, releasing cytokines and chemokines; they may attract circulating monocytes and exert functions that can aggravate the symptoms or drive reparation processes. As a result, liver macrophages are potential therapeutic targets that can be oriented toward a variety of aims, with emergent nanotechnology platforms potentially offering new perspectives for macrophage vectorization. Macrophages play an essential role in the final destination of nanoparticles (NPs) in the organism, as they are involved in their uptake and trafficking in vivo. Different types of delivery nanosystems for macrophage recognition and targeting, such as liposomes, solid-lipid, polymeric, or metallic nanoparticles, have been developed. Passive targeting promotes the accumulation of the NPs in the liver due to their anatomical and physiological features. This process is modulated by NP characteristics such as size, charge, and surface modifications. Active targeting approaches with specific ligands may also be used to reach liver macrophages. In order to design new systems, the NP recognition mechanism of macrophages must be understood, taking into account that variations in local microenvironment may change the phenotype of macrophages in a way that will affect the uptake and toxicity of NPs. This kind of information may be applied to diseases where macrophages play a pathogenic role, such as metabolic disorders, infections, or cancer. The kinetics of nanoparticles strongly affects their therapeutic efficacy when administered in vivo. Release kinetics could predict the behavior of nanosystems targeting macrophages and be applied to improve their characteristics. PBPK models have been developed to characterize nanoparticle biodistribution in organs of the reticuloendothelial system (RES) such as liver or spleen. Another controversial issue is the possible toxicity of non-degradable nanoparticles, which in many cases accumulate in high percentages in macrophage clearance organs such as the liver, spleen, and kidney.

Differential Nanoparticle Sequestration by Macrophages and Scavenger Endothelial Cells Visualized in Vivo in Real-Time and at Ultrastructural Resolution

Despite the common knowledge that the reticuloendothelial system is largely responsible for blood clearance of systemically administered nanoparticles, the sequestration mechanism remains a "black box". Using transgenic zebrafish embryos with cell type-specific fluorescent reporters and fluorescently labeled model nanoparticles (70 nm SiO₂), we here demonstrate simultaneous three-color in vivo imaging of intravenously injected nanoparticles, macrophages, and scavenger endothelial cells (SECs). The trafficking processes were further revealed at ultrastructural resolution by transmission electron microscopy. We also find, using a correlative light-electron microscopy approach, that macrophages rapidly sequester nanoparticles via membrane adhesion and endocytosis (including macropinocytosis) within minutes after injection. In contrast, SECs trap single nanoparticles via scavenger receptor-mediated endocytosis, resulting in gradual sequestration with a time scale of hours. Inhibition of the scavenger receptors prevented SECs from accumulating nanoparticles but enhanced uptake in macrophages, indicating the competitive nature of nanoparticle clearance in vivo. To directly quantify the relative contributions of the two cell types to overall nanoparticle sequestration, the differential sequestration kinetics was studied within the first 30 min post-injection. This revealed a much higher and increasing relative contribution of SECs, as they by far outnumber macrophages in zebrafish embryos, suggesting the importance of the macrophage:SECs ratio in a given tissue. Further characterizing macrophages on their efficiency in nanoparticle clearance, we show that inflammatory stimuli diminish the uptake of nanoparticles per cell. Our study demonstrates the strength of transgenic zebrafish embryos for intravital real-time and ultrastructural imaging of nanomaterials that may provide mechanistic insights into nanoparticle clearance in rodent models and humans.

Biodegradable Mesoporous Silica Achieved via Carbon Nanodots-Incorporated Framework Swelling for Debris-Mediated Photothermal Synergistic Immunotherapy

Incorporating carbon nanodots (CDs) into mesoporous silica framework for extensive biomedicine, especially for the desirable cancer immunotherapy, is considered to be an unexplored challenge. Herein, a hydrogen bond/electrostatic-assisted co-assembly strategy was smartly exploited to uniformly incorporate polymer-coated CDs into ordered framework of mesoporous silica nanoparticles (CD@MSNs). The obtained CD@MSN was not only biodegradable via the framework-incorporated CD-induced swelling but also capable of gathering dispersive CDs with enhanced photothermal effect and elevated targeting accumulation, which therefore can achieve photothermal imaging-guided photothermal therapy (PTT) in vitro and in vivo. Interestingly, benefiting from the biodegraded debris, it was found that CD@MSN-mediated PTT can synergistically achieve immune-mediated inhibition of tumor metastasis via stimulating the proliferation and activation of natural killer cells and macrophages with simultaneously up-regulating the secretion of corresponding cytokines (IFN-γ and Granzyme B). This work proposed an unusual synthesis of biodegradable mesoporous silica and provided an innovative insight into the biodegradable nanoparticles-associated anticancer immunity.

Nanotherapeutics interfere with cellular redox homeostasis for highly improved photodynamic therapy

Redox homeostasis inside malignant cells is a defense mechanism against the reactive oxygen species (ROS)-induced therapy means, but little importance has been paid to this innate barrier. The present study intends to make cancer cells more sensitive to the ROS-induced therapy by disturbing cellular redox homeostasis. To verify this concept, a porous metal-organic framework (MOF) serves not only as the photodynamic therapy (PDT) agent but also as the carrier to transport alkaloid piperlongumine (PL), a thioredoxin reductase (TrxR) inhibitor used to disturb cellular redox homeostasis. The PL-loaded MOF was further coated with cancer cell membranes to gain homologous tumor-targeting capability. Inside tumor cells, the released PL can effectively block the TrxR-mediated ROS elimination pathway. The resultant data show that compared to traditional PDT alone, the combination of PDT and TrxR inhibition causes profound promotions in cellular ROS level by about 1.6 times, in cytotoxicity by about 2 times, and in cellular apoptosis/necrosis rate by about 3 times. Consequently, this strategy based on the interference with cellular redox homeostasis has demonstrated high potency to improve the anticancer PDT performance, adumbrating a new way to boost the power of ROS-induced therapy.

Subchronic toxicity of silica nanoparticles as a function of size and porosity

Despite increasing reports of using silica nanoparticles (SNPs) for controlled drug delivery applications, their long-term toxicity profile following intravenous administration remains unexplored. Herein, we investigated the acute (10-day) and subchronic (60-day and 180-day) toxicity of nonporous SNPs of approximately 50 nm (Stöber SNPs50) and approximately 500 nm in diameter (Stöber SNPs500), and mesoporous SNPs of approximately 500 nm in diameter (MSNPs500) upon single-dose intravenous injection into male and female immune-competent inbred BALB/c mice. The Maximum Tolerated Dose (MTD) of the particles was determined 10 days post-injection. The MTD of SNPs was administered and toxicity evaluated over 60 and 180 days. Results demonstrate that Stöber SNPs50 exhibit systemic toxicity with MTD of 103 ± 11 mg.kg-1 for female and 100 ± 6 mg.kg-1 for male mice, respectively. Toxicity was alleviated by increasing the size of the particles (Stöber SNPs500). MTD values of 303 ± 4 mg.kg-1 for female and 300 ± 13 mg.kg-1 for male were observed for Stöber SNPs500. Mesoporous SNPs500 showed considerable systemic sex-related toxicity, with MTDs ranging from 40 ± 2 mg.kg-1 to 95 ± 2 mg.kg-1 for male and female mice, respectively. Studies of SNPs showed blood toxicity as a function of physiochemical properties such as significant differences in the mean corpuscular hemoglobin (MCHC) and platelet number at day 10 and white blood cell count at day 60. Histological examination also showed size-, porosity- and time-dependent tissue toxicity. Stöber SNPs500 caused major toxic effects such as lung thrombosis, cardiac wall fibrosis and calcifications, brain infarctions with necrotizing inflammatory response, infiltrate, retinal injuries with calcification and focal gliosis, renal parenchymal damage and liver lobular inflammation dependent on the dose and time of exposure. However, tissue toxicity and accumulation of SNPs in liver observed at day 10 was greater than at day 60 and much greater than at day 180. In contrast, a dramatic increase in cytokine levels was observed at day 60. Despite the relatively high doses, SNPs did not cause subchronic toxicity at day 180 after single-dose intravenous injection. However, they showed distinct differences in the 60 day in vivo subchronic toxicity and inflammation profile as a function of surface area and size.