Bridge over troubled waters: understanding the synthetic and biological identities of engineered nanomaterials

Assessing gut barrier integrity and reproductive performance following pre-mating oral administration of solid-lipid-nanoparticles designed for drug delivery

Solid lipid nanoparticles (SLNs) have gained interest as drug delivery carriers due to their efficient cellular internalization and increased therapeutic effect of the loaded drug, with minimal side effects. Although recently several studies have shown the possibility to administer SLNs during pregnancy to vehicle mRNA to the placenta, data about the effect of premating exposure to SLNs on pregnancy outcome are scant. Considering that assumption of drug-delivering nanocarriers in reproductive age may potentially affect women's reproductive health, the aim of the present study was to evaluate whether repeated oral administration of SLNs to female mice prior to mating would influence key pregnancy outcomes. For this purpose, SLNs melatonin loaded (SLN + mlt) or unloaded were orally administered to CD1 female mice at two different dosages-low (7.5 mg/kg) and high (750 mg/kg) -three times a week for 6 weeks. Females mice were mated and pregnancy was monitored from conception to delivery. All the assessed pregnancy parameters, including time to pregnancy, pregnancy duration, litter size, and the presence of any gross anomalies in the pups, and maternal key biochemical parameters were not significantly affected by SLN administration. Embryonic development was also evaluated and no effects on the number of implantation sites, fetus numbers, incidence of fetal resorptions, and measurements of crown-rump length, as well as fetal and placental weights, were observed in the treated mothers. The impact of SLNs on maternal intestinal barrier integrity and inflammation was assessed both in vivo in mice and in vitro using an intestinal epithelial barrier model by qRT-PCR. Results showed that unloaded SLNs, but not the SLN + mlt, affected intestinal barrier integrity. Although variation in the expression of inflammatory cytokines was recorded, this did not reflect in significant histological alterations and the integrity of the intestinal barrier was maintained. The in vitro model further confirmed the biocompatibility of SLNs, showing that both loaded and unloaded SLNs did not affect the integrity of the simulated intestinal epithelial barrier. In conclusion, these data suggest that administering SLNs, as a drug delivery vehicle, prior to conception does not affect either maternal health or fetal development, posing no risk to future pregnancy.

Epigenetic frontiers: miRNAs, long non-coding RNAs and nanomaterials are pioneering to cancer therapy

Cancer has arisen from both genetic mutations and epigenetic changes, making epigenetics a crucial area of research for innovative cancer prevention and treatment strategies. This dual perspective has propelled epigenetics into the forefront of cancer research. This review highlights the important roles of DNA methylation, histone modifications and non-coding RNAs (ncRNAs), particularly microRNAs (miRNAs) and long non-coding RNAs, which are key regulators of cancer-related gene expression. It explores the potential of epigenetic-based therapies to revolutionize patient outcomes by selectively modulating specific epigenetic markers involved in tumorigenesis. The review examines promising epigenetic biomarkers for early cancer detection and prognosis. It also highlights recent progress in oligonucleotide-based therapies, including antisense oligonucleotides (ASOs) and antimiRs, to precisely modulate epigenetic processes. Furthermore, the concept of epigenetic editing is discussed, providing insight into the future role of precision medicine for cancer patients. The integration of nanomedicine into cancer therapy has been explored and offers innovative approaches to improve therapeutic efficacy. This comprehensive review of recent advances in epigenetic-based cancer therapy seeks to advance the field of precision oncology, ultimately culminating in improved patient outcomes in the fight against cancer.

Affinity Constants of Bovine Serum Albumin for 5 nm Gold Nanoparticles (AuNPs) with ω-Functionalized Thiol Monolayers Determined by Fluorescence Spectroscopy

A detailed understanding of the binding of serum proteins to small (dcore <10 nm) nanoparticles (NPs) is essential for the mediation of protein corona formation in next generation nanotherapeutics. While a number of studies have investigated the details of protein adsorption on large functionalized NPs, small NPs (with a particle surface area comparable in size to the protein) have not received extensive study. This study determined the affinity constant (Ka) of BSA when binding to three different functionalized 5 nm gold nanoparticles (AuNPs). AuNPs were synthesized using three ω-functionalized thiols (mercaptoethoxy-ethoxy-ethanol (MEEE), mercaptohexanoic acid (MHA), and mercaptopentyltrimethylammonium chloride (MPTMA)), giving rise to particles with three different surface charges. The binding affinity of bovine serum albumin (BSA) to the different AuNP surfaces was investigated using UV-visible absorbance spectroscopy, dynamic light scattering (DLS), and fluorescence quenching titrations. Fluorescence titrations indicated that the affinity of BSA was actually highest for small AuNPs with a negative surface charge (MHA-AuNPs). Interestingly, the positively charged MPTMA-AuNPs showed the lowest Ka for BSA, indicating that electrostatic interactions are likely not the primary driving force in binding of BSA to these small AuNPs. Ka values at 25 °C for MHA, MEEE, and MPTMA-AuNPs were 5.2 ± 0.2 × 107, 3.7 ± 0.2 × 107, and 3.3 ± 0.16 × 107 M-1 in water, respectively. Fluorescence quenching titrations performed in 100 mM NaCl resulted in lower Ka values for the charged AuNPs, while the Ka value for the MEEE-AuNPs remained unchanged. Measurement of the hydrodynamic diameter (Dh) by dynamic light scattering (DLS) suggests that adsorption of 1-2 BSA molecules is sufficient to saturate the AuNP surface. DLS and negative-stain TEM images indicate that, despite the lower observed Ka values, the binding of MPTMA-AuNPs to BSA likely induces significant protein misfolding and may lead to extensive BSA aggregation at specific BSA:AuNP molar ratios.

Magnetic Nanostructures and Stem Cells for Regenerative Medicine, Application in Liver Diseases

The term "liver disease" refers to any hepatic condition that leads to tissue damage or altered hepatic function and can be induced by virus infections, autoimmunity, inherited genetic mutations, high consumption of alcohol or drugs, fat accumulation, and cancer. Some types of liver diseases are becoming more frequent worldwide. This can be related to increasing rates of obesity in developed countries, diet changes, higher alcohol intake, and even the coronavirus disease 2019 (COVID-19) pandemic was associated with increased liver disease-related deaths. Although the liver can regenerate, in cases of chronic damage or extensive fibrosis, the recovery of tissue mass is impossible, and a liver transplant is indicated. Because of reduced organ availability, it is necessary to search for alternative bioengineered solutions aiming for a cure or increased life expectancy while a transplant is not possible. Therefore, several groups were studying the possibility of stem cells transplantation as a therapeutic alternative since it is a promising strategy in regenerative medicine for treating various diseases. At the same time, nanotechnological advances can contribute to specifically targeting transplanted cells to injured sites using magnetic nanoparticles. In this review, we summarize multiple magnetic nanostructure-based strategies that are promising for treating liver diseases.

Changes of physico-chemical properties of nano-biomaterials by digestion fluids affect the physiological properties of epithelial intestinal cells and barrier models

Background

The widespread use of nano-biomaterials (NBMs) has increased the chance of human exposure. Although ingestion is one of the major routes of exposure to NBMs, it is not thoroughly studied to date. NBMs are expected to be dramatically modified following the transit into the oral-gastric-intestinal (OGI) tract. How these transformations affect their interaction with intestinal cells is still poorly understood. NBMs of different chemical nature—lipid-surfactant nanoparticles (LSNPs), carbon nanoparticles (CNPs), surface modified Fe₃O₄ nanoparticles (FNPs) and hydroxyapatite nanoparticles (HNPs)—were treated in a simulated human digestive system (SHDS) and then characterised. The biological effects of SHDS-treated and untreated NBMs were evaluated on primary (HCoEpiC) and immortalised (Caco-2, HCT116) epithelial intestinal cells and on an intestinal barrier model.

Results

The application of the in vitro SDHS modified the biocompatibility of NBMs on gastrointestinal cells. The differences between SHDS-treated and untreated NBMs could be attributed to the irreversible modification of the NBMs in the SHDS. Aggregation was detected for all NBMs regardless of their chemical nature, while pH- or enzyme-mediated partial degradation was detected for hydroxyapatite or polymer-coated iron oxide nanoparticles and lipid nanoparticles, respectively. The formation of a bio-corona, which contains proteases, was also demonstrated on all the analysed NBMs. In viability assays, undifferentiated primary cells were more sensitive than immortalised cells to digested NBMs, but neither pristine nor treated NBMs affected the intestinal barrier viability and permeability. SHDS-treated NBMs up-regulated the tight junction genes (claudin 3 and 5, occludin, zonula occludens 1) in intestinal barrier, with different patterns between each NBM, and increase the expression of both pro- and anti-inflammatory cytokines (IL-1β, TNF-α, IL-22, IL-10). Notably, none of these NBMs showed any significant genotoxic effect.

Conclusions

Overall, the results add a piece of evidence on the importance of applying validated in vitro SHDS models for the assessment of NBM intestinal toxicity/biocompatibility. We propose the association of chemical and microscopic characterization, SHDS and in vitro tests on both immortalised and primary cells as a robust screening pipeline useful to monitor the changes in the physico-chemical properties of ingested NBMs and their effects on intestinal cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00491-w.

Understanding the immunological interactions of engineered nanomaterials: Role of the bio-corona

Engineered nanomaterials are a broad class of materials with the potential for breakthrough applications in many sectors of society not least in medicine. Consequently, safety assessment of nanomaterials and nano-enabled products with respect to human health and the environment is of key importance. To this end, the biological interactions of nanoscale materials must be understood. Here, the dual "identities" of nanomaterials, namely, the material-intrinsic properties or synthetic identity and the acquired, context-dependent properties or biological identity, are discussed in relation to nanomaterial interactions with the immune system, our main defense against foreign intrusion. Specifically, we address whether macrophages and other innate immune cells respond to the synthetic identity or the biological identity of nanomaterials, that is, the surface adsorbed proteins and/or other biomolecules known as the bio-corona, or both? This article is categorized under: Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials.

Delivery of Oligonucleotide Therapeutics: Chemical Modifications, Lipid Nanoparticles, and Extracellular Vesicles

Oligonucleotides (ONs) comprise a rapidly growing class of therapeutics. In recent years, the list of FDA-approved ON therapies has rapidly expanded. ONs are small (15-30 bp) nucleotide-based therapeutics which are capable of targeting DNA and RNA as well as other biomolecules. ONs can be subdivided into several classes based on their chemical modifications and on the mechanisms of their target interactions. Historically, the largest hindrance to the widespread usage of ON therapeutics has been their inability to effectively internalize into cells and escape from endosomes to reach their molecular targets in the cytosol or nucleus. While cell uptake has been improved, "endosomal escape" remains a significant problem. There are a range of approaches to overcome this, and in this review, we focus on three: altering the chemical structure of the ONs, formulating synthetic, lipid-based nanoparticles to encapsulate the ONs, or biologically loading the ONs into extracellular vesicles. This review provides a background to the design and mode of action of existing FDA-approved ONs. It presents the most common ON classifications and chemical modifications from a fundamental scientific perspective and provides a roadmap of the cellular uptake pathways by which ONs are trafficked. Finally, this review delves into each of the above-mentioned approaches to ON delivery, highlighting the scientific principles behind each and covering recent advances.

The Extracellular Matrix in Pancreatic Cancer: Description of a Complex Network and Promising Therapeutic Options

The stroma is a relevant player in driving and supporting the progression of pancreatic ductal adenocarcinoma (PDAC), and a large body of evidence highlights its role in hindering the efficacy of current therapies. In fact, the dense extracellular matrix (ECM) characterizing this tumor acts as a natural physical barrier, impairing drug penetration. Consequently, all of the approaches combining stroma-targeting and anticancer therapy constitute an appealing option for improving drug penetration. Several strategies have been adopted in order to target the PDAC stroma, such as the depletion of ECM components and the targeting of cancer-associated fibroblasts (CAFs), which are responsible for the increased matrix deposition in cancer. Additionally, the leaky and collapsing blood vessels characterizing the tumor might be normalized, thus restoring blood perfusion and allowing drug penetration. Even though many stroma-targeting strategies have reported disappointing results in clinical trials, the ECM offers a wide range of potential therapeutic targets that are now being investigated. The dense ECM might be bypassed by implementing nanoparticle-based systems or by using mesenchymal stem cells as drug carriers. The present review aims to provide an overview of the principal mechanisms involved in the ECM remodeling and of new promising therapeutic strategies for PDAC.

The effect of short silica fibers (0.3 μm 3.2 μm) on macrophages

Silica fibers with a dimension of 0.3 μm ∙ 3.2 μm² nm were prepared by a modified Stöber synthesis as model particles. The particles were characterized by scanning electron microscopy, elemental analysis, thermogravimetry and X-ray powder diffraction. Their uptake by macrophages (THP-1 cells and NR8383 cells) was studied by confocal laser scanning microscopy and scanning electron microscopy. The uptake by cells was very high, but the silica fibers were not harmful to NR8383 cells in concentrations up to 100 μg mL^-1. Only above 100 μg mL^-1, significant cell toxic effects were observed, probably induced by a high dose of particles that had sedimented on the cells and led to the adverse effects. The chemotactic response as assessed by the particle-induced migration assay (PICMA) was weak in comparison to a control of agglomerated silica particles. The as-prepared fibers were fully X-ray amorphous but crystallized to β-cristobalite after heating to 1000 °C and converted to α-cristobalite upon cooling to ambient temperature. The fibers had sintered to larger aggregates but retained their elongated primary shape. The particle cytotoxicity towards THP-1 cells was not significantly enhanced by the crystallization.

Drug Delivery With Carbon-Based Nanomaterials as Versatile Nanocarriers: Progress and Prospects

With growing interest, a large number of researches have been conducted on carbon-based nanomaterials (CBNs). However, their uses are limited due to comprehensive potential environmental and human health effects. It is often confusing for researchers to make an informed choice regarding the versatile carbon-based nanocarrier system and its potential applications. This review has highlighted emerging applications and cutting-edge progress of CBNs in drug delivery. Some critical factors like enzymatic degradation, surface modification, biological interactions, and bio-corona have been discussed here. These factors will help to fabricate CBNs for effective drug delivery. This review also addresses recent advancements in carbon-based target specific and release controlled drug delivery to improve disease treatment. The scientific community has turned their research efforts into the development of novel production methods of CBNs to make their production more attractive to the industrial sector. Due to the nanosize and diversified physical properties, these CBNs have demonstrated distinct biological interaction. Thus long-term preclinical toxicity study is recommended before finally translating to clinical application.

Interplay between extracellular polymeric substances (EPS) from a marine diatom and model nanoplastic through eco-corona formation

The occurrence of nanoplastics in oceans' surface waters is no more a hypothesis and it could severely affect marine organisms from different trophic levels. Nanoscale particles interaction with dissolved natural organic matter (NOM) significantly influence their behaviour and consequently bioavailability and toxicity to marine species. Extracellular polymeric substances (EPS) are among the main components of the NOM pool in seawater yet have been so far little investigated for their effect in altering the physical-chemical properties of nanosized objects. Here we employed EPS from marine diatom Phaeodactylum tricornutum to study the evolution of an eco-corona formation upon incubation with 60 nm carboxylated polystyrene nanoparticles (PS-COOH NPs), as proxy for nanoplastics in seawater. EPS significantly reduced PS-COOH NPs aggregation rate compared to biomolecule free natural seawater (NSW) and caused the formation of complexes constituted by both carbohydrate and protein components. Size Exclusion Chromatography (SEC) revealed four main distinct groups of peaks, spanning from high (>100 kDa) to low molecular weight (20 kDa) molecules, characterized by a high chemical heterogeneity. The lowering of the chromatographic signals detected after EPS incubation with PS-COOH NPs, mainly in the eluates at high molecular weight, suggests that an important fraction of EPS remained adsorbed on PS-COOH NPs. In agreement, SDS-PAGE analysis of proteins adsorbed on PS-COOH showed the occurrence of an eco-corona formed by proteins in the range of molecular weight 30-100 kDa. No toxicity to diatoms was observed upon PS-COOH exposure (72 h, 1-100 mg L^-1) even by adding a further source of exogenous EPS during exposure. Moreover, the addition of EPS reduced ROS production, even when cells were incubated with PS-COOH NPs at 10 and 50 mg L^-1, suggesting an antioxidant scavenging activity of EPS.

The Intrinsic Biological Identities of Iron Oxide Nanoparticles and Their Coatings: Unexplored Territory for Combinatorial Therapies

Over the last 20 years, iron oxide nanoparticles (IONPs) have been the subject of increasing investigation due to their potential use as theranostic agents. Their unique physical properties (physical identity), ample possibilities for surface modifications (synthetic identity), and the complex dynamics of their interaction with biological systems (biological identity) make IONPs a unique and fruitful resource for developing magnetic field-based therapeutic and diagnostic approaches to the treatment of diseases such as cancer. Like all nanomaterials, IONPs also interact with different cell types in vivo, a characteristic that ultimately determines their activity over the short and long term. Cells of the mononuclear phagocytic system (macrophages), dendritic cells (DCs), and endothelial cells (ECs) are engaged in the bulk of IONP encounters in the organism, and also determine IONP biodistribution. Therefore, the biological effects that IONPs trigger in these cells (biological identity) are of utmost importance to better understand and refine the efficacy of IONP-based theranostics. In the present review, which is focused on anti-cancer therapy, we discuss recent findings on the biological identities of IONPs, particularly as concerns their interactions with myeloid, endothelial, and tumor cells. Furthermore, we thoroughly discuss current understandings of the basic molecular mechanisms and complex interactions that govern IONP biological identity, and how these traits could be used as a stepping stone for future research.

Zinc Oxide Nanowires Exposure Induces a Distinct Inflammatory Response via CCL11-Mediated Eosinophil Recruitment

High aspect ratio zinc oxide nanowires (ZnONWs) have become one of the most important products in nanotechnology. The wide range applications of ZnONWs have heightened the need for evaluating the risks and biological consequences to these particles. In this study, we investigated inflammatory pathways activated by ZnONWs in cultured cells as well as the consequences of systemic exposure in mouse models. Confocal microscopy showed rapid phagocytic uptake of FITC-ZnONWs by macrophages. Exposure of macrophages or lung epithelial cells to ZnONWs induced the production of CCL2 and CCL11. Moreover, ZnONWs exposure induced both IL-6 and TNF-α production only in macrophages but not in LKR13 cells. Intratracheal instillation of ZnONWs in C57BL/6 mice induced a significant increase in the total numbers of immune cells in the broncho alveolar lavage fluid (BALFs) 2 days after instillation. Macrophages and eosinophils were the predominant cellular infiltrates of ZnONWs exposed mouse lungs. Similar cellular infiltrates were also observed in a mouse air-pouch model. Pro-inflammatory cytokines IL-6 and TNF-α as well as chemokines CCL11, and CCL2 were increased both in BALFs and air-pouch lavage fluids. These results suggest that exposure to ZnONWs may induce distinct inflammatory responses through phagocytic uptake and formation of soluble Zn²⁺ ions.

Overview of the blood compatibility of nanomedicines: A trend analysis of in vitro and in vivo studies

As nanomedicines have the potential to address many currently unmet medical needs, the early identification of regulatory requirements that could hamper a smooth translation of nanomedicines from the laboratory environment to clinical applications is of utmost importance. The blood system is especially relevant as many nanomedicinal products that are currently under development are designed for intravenous administration and cells of the blood system will be among the first biological systems exposed to the injected nanomedicine. This review collects and summarizes the current knowledge related to the blood compatibility of nanomedicines and nanomaterials with a potential use in biomedical applications. Different types of nanomedicines were analyzed for their toxicity to the blood system, and the role of their physicochemical properties was further elucidated. Trends were identified related to: (a) the nature of the most frequently occurring blood incompatibilities such as thrombogenicity and complement activation, (b) the contribution of physicochemical properties to these blood incompatibilities, and (c) the similarities between data retrieved from in vivo and in vitro studies. Finally, we provide an overview of available standards that allow evaluating the compatibility of a material with the blood system. This article is categorized under: Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials Therapeutic Approaches and Drug Discovery > Emerging Technologies Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine.

Usefulness of fish cell lines for the initial characterization of toxicity and cellular fate of graphene-related materials (carbon nanofibers and graphene oxide)

Graphene-related materials (GRMs) are one of the most attractive materials from an application perspective, consequently their release into aquatic environments is highly likely. In the present work, the potential of fish hepatocytes (topminnow fish hepatoma cell line, PLHC-1) and macrophages (carp leukocyte cell line, CLC) to study the toxicity and intracellular fate of helical-ribbon carbon nanofibers (CNFs) and graphene oxide (GO) used in a variety of intermediate industrial products was evaluated, allowing a first ranking of GRMs according to their cytotoxicity. Cells were exposed to a concentration range of 0-200 μg ml^-1 of GRMs for 24 and 72 h and cell viability was assessed by measuring mitochondrial activity (AlamarBlue assay), plasma membrane integrity (5-carboxyfluorescein diacetate-acetoxymethyl ester assay) and lysosomal function (neutral red uptake assay). Results showed that both the cell type and the choice of endpoint determined the toxicity of GRMs. In both cell lines, CNFs appeared to have higher toxicity than GO and the highest degree of graphitization in fibers was associated with lower toxicity. Transmission electron microscopy revealed that CNFs were taken up into membrane-bound compartments of PLHC-1 cells in a size-independent manner, whereas in CLC, longer CNFs were encountered free in the cytoplasm and only the shorter CNFs were localized in membrane-surrounded vesicles. GO sheets were present within vesicles as well as free in the cytoplasm of both cell types. These findings contribute to the understanding of the toxicity and behaviour of these GRMs in living systems, therefore aiding in designing safer materials for the environment.

How Entanglement of Different Physicochemical Properties Complicates the Prediction of in Vitro and in Vivo Interactions of Gold Nanoparticles

The physicochemical properties of a set of 21 different gold nanoparticles (spherical and rod-shaped nanoparticles (NPs) of different diameters with three different surface coatings) were studied. Protein corona formation, in vitro uptake, effect on cell viability and proliferation, and in vivo biodistribution of these NPs were determined. The relation of the results of the different NPs was analyzed by hierarchical cluster analysis, which will tell which NPs have the most similar physicochemical properties and biological effects, without having to specify individual physicochemical parameters. The results show that the physicochemical properties of gold nanoparticles (Au NPs) are mainly accounted for by their hydrodynamic diameter and their zeta-potential. The formation of the protein corona is determined by the pH-dependence of their zeta-potential. While several reports found that in vitro uptake and in vivo biodistribution of NPs are correlated to individual physicochemical parameters, e. g., size, shape, or surface chemistry, such direct dependence in the investigated multidimensional set of NPs was not found in our study. This most likely is due to entanglement of the different parameters, which complicates the prediction of the biological effect of NPs in case multiple physicochemical properties are simultaneously varied. The in vitro uptake and in vivo biodistribution of NPs seem to be not directly driven by the protein corona, but the physicochemical properties determine as well the corona as they influence in vitro/ in vivo behaviors, and thus the effect of the protein corona would be rather indirect.

Nanomedicine: Principles, Properties, and Regulatory Issues

Several scientific areas have benefited significantly from the introduction of nanotechnology and the respective evolution. This is especially noteworthy in the development of new drug substances and products. This review focuses on the introduction of nanomedicines in the pharmaceutical market, and all the controversy associated to basic concepts related to these nanosystems, and the numerous methodologies applied for enhanced knowledge. Due to the properties conferred by the nanoscale, the challenges for nanotechnology implementation, specifically in the pharmaceutical development of new drug products and respective regulatory issues are critically discussed, mainly focused on the European Union context. Finally, issues pertaining to the current applications and future developments are presented.

Dynamic analysis of the interactions between Si/SiO2 quantum dots and biomolecules for improving applications based on nano-bio interfaces

Due to their outstanding properties, quantum dots (QDs) received a growing interest in the biomedical field, but it is of major importance to investigate and to understand their interaction with the biomolecules. We examined the stability of silicon QDs and the time evolution of QDs – protein corona formation in various biological media (bovine serum albumin, cell culture medium without or supplemented with 10% fetal bovine serum-FBS). Changes in the secondary structure of BSA were also investigated over time. Hydrodynamic size and zeta potential measurements showed an evolution in time indicating the nanoparticle-protein interaction. The protein corona formation was also dependent on time, albumin adsorption reaching the peak level after 1 hour. The silicon QDs adsorbed an important amount of FBS proteins from the first 5 minutes of incubation that was maintained for the next 8 hours, and diminished afterwards. Under protein-free conditions the QDs induced cell membrane damage in a time-dependent manner, however the presence of serum proteins attenuated their hemolytic activity and maintained the integrity of phosphatidylcholine layer. This study provides useful insights regarding the dynamics of BSA adsorption and interaction of silicon QDs with proteins and lipids, in order to understand the role of QDs biocorona.

Nanoparticle impact on innate immune cell pattern-recognition receptors and inflammasomes activation

Nanotechnology-based strategies can dramatically impact the treatment, prevention and diagnosis of a wide range of diseases. Despite the unprecedented success achieved with the use of nanomaterials to address unmet biomedical needs and their particular suitability for the effective application of a personalized medicine, the clinical translation of those nanoparticulate systems has still been impaired by the limited understanding on their interaction with complex biological systems. As a result, unexpected effects due to unpredicted interactions at biomaterial and biological interfaces have been underlying the biosafety concerns raised by the use of nanomaterials. This review explores the current knowledge on how nanoparticle (NP) physicochemical and surface properties determine their interactions with innate immune cells, with particular attention on the activation of pattern-recognition receptors and inflammasome. A critical perspective will additionally address the impact of biological systems on the effect of NP on immune cell activity at the molecular level. We will discuss how the understanding of the NP-innate immune cell interactions can significantly add into the clinical translation by guiding the design of nanomedicines with particular effect on targeted cells, thus improving their clinical efficacy while minimizing undesired but predictable toxicological effects.

Protein bio-corona: critical issue in immune nanotoxicology

With the expansion of the nanomedicine field, the knowledge focusing on the behavior of nanoparticles in the biological milieu has rapidly escalated. Upon introduction to a complex biological system, nanomaterials dynamically interact with all the encountered biomolecules and form the protein "bio-corona." The decoration with these surface biomolecules endows nanoparticles with new properties. The present review will address updates of the protein bio-corona characteristics as influenced by nanoparticle's physicochemical properties and by the particularities of the encountered biological milieu. Undeniably, bio-corona generation influences the efficacy of the nanodrug and guides the actions of innate and adaptive immunity. Exploiting the dynamic process of protein bio-corona development in combination with the new engineered horizons of drugs linked to nanoparticles could lead to innovative functional nanotherapies. Therefore, bio-medical nanotechnologies should focus on the interactions of nanoparticles with the immune system for both safety and efficacy reasons.

Stealth Immune Properties of Graphene Oxide Enabled by Surface-Bound Complement Factor H

With mounting evidence that nanomaterials can trigger adverse innate immune responses such as complement activation, there is increasing attention to the development of strategies that mask the complement-activating properties of nanomaterials. The current gold standard to reduce complement activation of nanomaterials is the covalent attachment of polymer coatings on nanomaterial surfaces, even though this strategy provides only moderate protection against complement activation. Akin to protein coronas that form on nanomaterial surfaces in physiological fluids, noncovalent strategies based on protein adsorption would offer a simplified, biomimetic approach to mitigate complement activation. Herein, we demonstrate that precoating graphene-based nanomaterials with purified, natural proteins enables regulatory control of nanomaterial-triggered complement activation. When the graphene-based nanomaterials were coated with complement factor H, nearly complete protection (>90% reduction) against complement activation (a "stealth effect") was achieved. By contrast, coating the nanomaterials with a passivating layer of bovine or human serum albumins achieved moderate protection (∼40% reduction), whereas immunoglobulin G amplified complement activation by several-fold. Taken together, our results demonstrate that surface-bound factor H, as well as serum albumins, can prevent graphene oxide-triggered complement activation, thereby offering a facile approach to inhibit complement activation completely down to naturally occurring levels.

Quantitative uptake of colloidal particles by cell cultures

The use of nanotechnologies involving nano- and microparticles has increased tremendously in the recent past. There are various beneficial characteristics that make particles attractive for a wide range of technologies. However, colloidal particles on the other hand can potentially be harmful for humans and environment. Today, complete understanding of the interaction of colloidal particles with biological systems still remains a challenge. Indeed, their uptake, effects, and final cell cycle including their life span fate and degradation in biological systems are not fully understood. This is mainly due to the complexity of multiple parameters which need to be taken in consideration to perform the nanosafety research. Therefore, we will provide an overview of the common denominators and ideas to achieve universal metrics to assess their safety. The review discusses aspects including how biological media could change the physicochemical properties of colloids, how colloids are endocytosed by cells, how to distinguish between internalized versus membrane-attached colloids, possible correlation of cellular uptake of colloids with their physicochemical properties, and how the colloidal stability of colloids may vary upon cell internalization. In conclusion three main statements are given. First, in typically exposure scenarios only part of the colloids associated with cells are internalized while a significant part remain outside cells attached to their membrane. For quantitative uptake studies false positive counts in the form of only adherent but not internalized colloids have to be avoided. pH sensitive fluorophores attached to the colloids, which can discriminate between acidic endosomal/lysosomal and neutral extracellular environment around colloids offer a possible solution. Second, the metrics selected for uptake studies is of utmost importance. Counting the internalized colloids by number or by volume may lead to significantly different results. Third, colloids may change their physicochemical properties along their life cycle, and appropriate characterization is required during the different stages.

Nanoparticle transport across the placental barrier: pushing the field forward!

The human placenta is a multifunctional organ constituting the barrier between maternal and fetal tissues. Nanoparticles can cross the placental barrier, and there is increasing evidence that the extent of transfer is dependent on particle characteristics and functionalization. While translocated particles may pose risks to the growing fetus particles may also be engineered to enable new particle-based therapies in pregnancy. In both cases, a comprehensive understanding of nanoparticle uptake, accumulation and translocation is indispensable and requires predictive placental transfer models. We examine and evaluate the current literature to draw first conclusions on the possibility to steer translocation of nanoparticles. In addition, we discuss if current placental models are suitable for nanoparticle transfer studies and suggest strategies to improve their predictability.

Biological interactions of carbon-based nanomaterials: From coronation to degradation

Carbon-based nanomaterials including carbon nanotubes, graphene oxide, fullerenes and nanodiamonds are potential candidates for various applications in medicine such as drug delivery and imaging. However, the successful translation of nanomaterials for biomedical applications is predicated on a detailed understanding of the biological interactions of these materials. Indeed, the potential impact of the so-called bio-corona of proteins, lipids, and other biomolecules on the fate of nanomaterials in the body should not be ignored. Enzymatic degradation of carbon-based nanomaterials by immune-competent cells serves as a special case of bio-corona interactions with important implications for the medical use of such nanomaterials. In the present review, we highlight emerging biomedical applications of carbon-based nanomaterials. We also discuss recent studies on nanomaterial 'coronation' and how this impacts on biodistribution and targeting along with studies on the enzymatic degradation of carbon-based nanomaterials, and the role of surface modification of nanomaterials for these biological interactions.

FROM THE CLINICAL EDITOR

Advances in technology have produced many carbon-based nanomaterials. These are increasingly being investigated for the use in diagnostics and therapeutics. Nonetheless, there remains a knowledge gap in terms of the understanding of the biological interactions of these materials. In this paper, the authors provided a comprehensive review on the recent biomedical applications and the interactions of various carbon-based nanomaterials.

Stromal barriers and strategies for the delivery of nanomedicine to desmoplastic tumors

Nanoparticle based delivery formulations have become a leading delivery strategy for cancer imaging and therapy. The success of nanoparticle-based therapy relies heavily on their ability to utilize the enhanced permeability and retention (EPR) effect and active targeting moieties to their advantage. However, these methods often fail to enable a uniform NP distribution across the tumor, and lead to insufficient local concentrations of drug. Oftentimes, this heterogeneous drug distribution is one of the primary reasons for suboptimal treatment efficacy in NP delivery platforms. Herein, we seek to examine the biophysical causes of heterogeneous NP distribution in stroma-rich desmoplastic tumors; namely the abnormal tumor vasculature, deregulated extracellular matrix and high interstitial hypertension associated with these tumors. It is suggested that these factors help explain the discrepancy between promising outlooks for many NP formulations in preclinical studies, but suboptimal clinical outcomes for most FDA approved nanoformulations. Furthermore, examination into the role of the physicochemical properties of NPs on successful drug delivery was conducted in this review. In light of the many formidable barriers against successful NP drug delivery, we provided possible approaches to mitigate delivery issues from the perspective of stromal remodeling and NP design. In all, this review seeks to provide guidelines for optimizing nanoparticle-based cancer drug delivery through both modified nanoparticle design and alleviation of biological barriers to successful therapy.

Nanoparticle dosage-a nontrivial task of utmost importance for quantitative nanosafety research

For a detailed and correct understanding of effects of colloidal nanoparticles exposed to organisms, a correlation of such effects to the physicochemical properties of the nanoparticles is a necessity. Such correlation is complex by the fact that many physicochemical parameters such as size, shape, surface charge, and colloidal stability are interlinked, and nontrivial to experimentally determine. This review aims to give an overview regarding such correlations. Particular focus will be given on the role of determining nanoparticle concentrations, which is the basis for most quantitative toxicity evaluations. A comparison of mass versus particle number concentrations is given, and their respective differences are highlighted. WIREs Nanomed Nanobiotechnol 2016, 8:479-492. doi: 10.1002/wnan.1378 For further resources related to this article, please visit the WIREs website.

Impact and effectiveness of risk mitigation strategies on the insurability of nanomaterial production: evidences from industrial case studies

Workers involved in producing nanomaterials or using nanomaterials in manufacturing plants are likely to have earlier and higher exposure to manufactured/engineered nanomaterials (ENM) than the general population. This is because both the volume handled and the probability of the effluence of 'free' nanoparticles from the handled volume are much higher during a production process than at any other stage in the lifecycle of nanomaterials and nanotechnology-enabled products. Risk assessment (RA) techniques using control banding (CB) as a framework for risk transfer represents a robust theory but further progress on implementing the model is required so that risk can be transferred to insurance companies. Following a review of RA in general and hazard measurement in particular, we subject a Structural Alert Scheme methodology to three industrial case studies using ZrO2 , TiO2 , and multi-walled carbon nanotubes (MWCNT). The materials are tested in a pristine state and in a remediated (coated) state, and the respective emission and hazard rates are tested alongside the material performance as originally designed. To our knowledge, this is the first such implementation of a CB RA in conjunction with an ENM performance test and offers both manufacturers and underwriters an insight into future applications.

Nanomedicine delivery: does protein corona route to the target or off road?

Nanomedicine aims to find novel solutions for urgent biomedical needs. Despite this, one of the most challenging hurdles that nanomedicine faces is to successfully target therapeutic nanoparticles to cells of interest in vivo. As for any biomaterials, once in vivo, nanoparticles can interact with plasma biomolecules, forming new entities for which the name protein coronas (PCs) have been coined. The PC can influence the in vivo biological fate of a nanoparticle. Thus for guaranteeing the desired function of an engineered nanomaterial in vivo, it is crucial to dissect its PC in terms of formation and evolution within the body. In this contribution we will review the 'good' and 'bad' sides of the PC, starting from the scientific aspects to the technological applications.

Of drug administration, war and oïkos: mediating cancer with nanomedicines

This paper focuses on nano-enabled drug delivery systems (NDDS) in the context of cancer medicine. It regards NDDS as relational objects whose modes of existence are defined by their relationships with a complex biocultural environment that includes both the biological processes of our bodies and the values representations and metaphors our societies associate with cancer and cancer therapy. Within this framework the abundant use of war metaphors in NDDS --from 'smart bombs' to 'magic nano-bullets'--is discussed from various angles: in terms of therapeutic efficacy, it limits the potential of the technique by preventing the inclusion of the (patho)biological environment in the nanomedicine's mode of action. In terms of development opportunities, the military strategy of active specific targeting faces cost and complexity bottlenecks. In terms of ethical values, it favors the questionable image of cancer patients as 'fighters'. On the basis of these criticisms different metaphorical frameworks are suggested, in particular that of oïkos, whereby nanomedicine is reframed as a kind of domestic economy addressing the system-environment relationships of embodied processes with further imagination and care.

Proteomics Analysis Reveals Distinct Corona Composition on Magnetic Nanoparticles with Different Surface Coatings: Implications for Interactions with Primary Human Macrophages

Superparamagnetic iron oxide nanoparticles (SPIONs) have emerged as promising contrast agents for magnetic resonance imaging. The influence of different surface coatings on the biocompatibility of SPIONs has been addressed, but the potential impact of the so-called corona of adsorbed proteins on the surface of SPIONs on their biological behavior is less well studied. Here, we determined the composition of the plasma protein corona on silica-coated versus dextran-coated SPIONs using mass spectrometry-based proteomics approaches. Notably, gene ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed distinct protein corona compositions for the two different SPIONs. Relaxivity of silica-coated SPIONs was modulated by the presence of a protein corona. Moreover, the viability of primary human monocyte-derived macrophages was influenced by the protein corona on silica-coated, but not dextran-coated SPIONs, and the protein corona promoted cellular uptake of silica-coated SPIONs, but did not affect internalization of dextran-coated SPIONs.

The One Year Fate of Iron Oxide Coated Gold Nanoparticles in Mice

Safe implementation of nanotechnology and nanomedicine requires an in-depth understanding of the life cycle of nanoparticles in the body. Here, we investigate the long-term fate of gold/iron oxide heterostructures after intravenous injection in mice. We show these heterostructures degrade in vivo and that the magnetic and optical properties change during the degradation process. These particles eventually eliminate from the body. The comparison of two different coating shells for heterostructures, amphiphilic polymer or polyethylene glycol, reveals the long lasting impact of initial surface properties on the nanocrystal degradability and on the kinetics of elimination of magnetic iron and gold from liver and spleen. Modulation of nanoparticles reactivity to the biological environment by the choice of materials and surface functionalization may provide new directions in the design of multifunctional nanomedicines with predictable fate.

Keeping it real: The importance of material characterization in nanotoxicology

Nanomaterials are small and the small size and corresponding large surface area of nanomaterials confers specific properties, making these materials desirable for various applications, not least in medicine. However, it is pertinent to ask whether size is the only property that matters for the desirable or detrimental effects of nanomaterials? Indeed, it is important to know not only what the material looks like, but also what it is made of, as well as how the material interacts with its biological surroundings. It has been suggested that guidelines should be implemented on the types of information required in terms of physicochemical characterization of nanomaterials for toxicological studies in order to improve the quality and relevance of the published results. This is certainly a key issue, but it is important to keep in mind that material characterization should be fit-for-purpose, that is, the information gathered should be relevant for the end-points being studied.

Nanotechnology in the war against cancer: new arms against an old enemy – a clinical view

ABSTRACT 

Clinical oncology is facing a paradigm shift. A new treatment philosophy is emerging and new targets are appearing that require new active agents. The medical use of nanotechnology – nanomedicine – holds several promising possibilities in the war against cancer. Some of these include: new formats for old drugs, that is, increasing efficacy while diminishing side effects; and new administration routes – that is, dermal, oral and pulmonary. In this overview, we describe some nanoparticles and their medical uses as well as highlight advantages of nanoparticles compared with conventional pharmaceuticals. We also point to some of the many technical challenges and potential risks with using nanotechnology for oncological applications.

Silicon-based quantum dots induce inflammation in human lung cells and disrupt extracellular matrix homeostasis

Quantum dots (QDs) are nanocrystalline semiconductor materials that have been tested for biological applications such as cancer therapy, cellular imaging and drug delivery, despite the serious lack of information of their effects on mammalian cells. The present study aimed to evaluate the potential of Si/SiO2 QDs to induce an inflammatory response in MRC-5 human lung fibroblasts. Cells were exposed to different concentrations of Si/SiO2 QDs (25-200 μg·mL(-1)) for 24, 48, 72 and 96 h. The results obtained showed that uptake of QDs was dependent on biocorona formation and the stability of nanoparticles in various biological media (minimum essential medium without or with 10% fetal bovine serum). The cell membrane damage indicated by the increase in lactate dehydrogenase release after exposure to QDs was dose- and time-dependent. The level of lysosomes increased proportionally with the concentration of QDs, whereas an accumulation of autophagosomes was also observed. Cellular morphology was affected, as shown by the disruption of actin filaments. The enhanced release of nitric oxide and the increase in interleukin-6 and interleukin-8 protein expression suggested that nanoparticles triggered an inflammatory response in MRC-5 cells. QDs decreased the protein expression and enzymatic activity of matrix metalloproteinase (MMP)-2 and MMP-9 and also MMP-1 caseinase activity, whereas the protein levels of MMP-1 and tissue inhibitor of metalloproteinase-1 increased. The present study reveals for the first time that silicon-based QDs are able to generate inflammation in lung cells and cause an imbalance in extracellular matrix turnover through a differential regulation of MMPs and tissue inhibitor of metalloproteinase-1 protein expression.

Next-generation sequencing reveals low-dose effects of cationic dendrimers in primary human bronchial epithelial cells

Gene expression profiling has developed rapidly in recent years with the advent of deep sequencing technologies such as RNA sequencing (RNA Seq) and could be harnessed to predict and define mechanisms of toxicity of chemicals and nanomaterials. However, the full potential of these technologies in (nano)toxicology is yet to be realized. Here, we show that systems biology approaches can uncover mechanisms underlying cellular responses to nanomaterials. Using RNA Seq and computational approaches, we found that cationic poly(amidoamine) dendrimers (PAMAM-NH2) are capable of triggering down-regulation of cell-cycle-related genes in primary human bronchial epithelial cells at doses that do not elicit acute cytotoxicity, as demonstrated using conventional cell viability assays, while gene transcription was not affected by neutral PAMAM-OH dendrimers. The PAMAMs were internalized in an active manner by lung cells and localized mainly in lysosomes; amine-terminated dendrimers were internalized more efficiently when compared to the hydroxyl-terminated dendrimers. Upstream regulator analysis implicated NF-κB as a putative transcriptional regulator, and subsequent cell-based assays confirmed that PAMAM-NH2 caused NF-κB-dependent cell cycle arrest. However, PAMAM-NH2 did not affect cell cycle progression in the human A549 adenocarcinoma cell line. These results demonstrate the feasibility of applying systems biology approaches to predict cellular responses to nanomaterials and highlight the importance of using relevant (primary) cell models.

A secretomics analysis reveals major differences in the macrophage responses towards different types of carbon nanotubes

Certain types of carbon nanotubes (CNT) can evoke inflammation, fibrosis and mesothelioma in vivo, raising concerns about their potential health effects. It has been recently postulated that NLRP3 inflammasome activation is important in the CNT-induced toxicity. However, more comprehensive studies of the protein secretion induced by CNT can provide new information about their possible pathogenic mechanisms. Here, we studied protein secretion from human macrophages with a proteomic approach in an unbiased way. Human monocyte-derived macrophages (MDM) were exposed to tangled or rigid, long multi-walled CNT (MWCNT) or crocidolite asbestos for 6 h. The growth media was concentrated and secreted proteins were analyzed using 2D-DIGE and DeCyder software. Subsequently, significantly up- or down-regulated protein spots were in-gel digested and identified with an LC-MS/MS approach. Bioinformatics analysis was performed to reveal the different patterns of protein secretion induced by these materials. The results show that both long rigid MWCNT and asbestos elicited ample and highly similar protein secretion. In contrast, exposure to long tangled MWCNT induced weaker protein secretion with a more distinct profile. Secretion of lysosomal proteins followed the exposure to all materials, suggesting lysosomal damage. However, only long rigid MWCNT was associated with apoptosis. This analysis suggests that the CNT toxicity in human MDM is mediated via vigorous secretion of inflammation-related proteins and apoptosis. This study provides new insights into the mechanisms of toxicity of high aspect ratio nanomaterials and indicates that not all types of CNT are as hazardous as asbestos fibers.

In vitro interaction of colloidal nanoparticles with mammalian cells: What have we learned thus far?

The interfacing of colloidal nanoparticles with mammalian cells is now well into its second decade. In this review our goal is to highlight the more generally accepted concepts that we have gleaned from nearly twenty years of research. While details of these complex interactions strongly depend, amongst others, upon the specific properties of the nanoparticles used, the cell type, and their environmental conditions, a number of fundamental principles exist, which are outlined in this review.

[Life cycle of magnetic nanoparticles in the organism]

The use of nanomaterials drastically increases and yet their behavior in living organisms remains poorly examined. At the same time a better comprehension of the interactions between nanoparticles and the biological environment would allow us to limit potential nanoparticle-based toxicity and fully exploit nanoparticles medical applications. In this perspective, it is high time we develop methods to detect, quantify and follow the evolution of nanoparticles in the complex biological environment, spanning all relevant scales from the nanometer up to the tissue level. In this work we follow the life cycle of magnetic nanoparticles in vivo, focusing on their transformations over time from administration to elimination. As opposed to traditional nano-toxicological approaches, we herein take the nanoparticle perspective and try to establish how biological environment might impact the particles properties and their fate (interaction with proteins, cell confinement, degradation...) from their initial state to a series of changes a nanoparticle might undergo on its journey throughout the organism.

Mechanism-based genotoxicity screening of metal oxide nanoparticles using the ToxTracker panel of reporter cell lines

BACKGROUND

The rapid expansion of manufacturing and use of nano-sized materials fuels the demand for fast and reliable assays to identify their potential hazardous properties and underlying mechanisms. The ToxTracker assay is a recently developed mechanism-based reporter assay based on mouse embryonic stem (mES) cells that uses GFP-tagged biomarkers for detection of DNA damage, oxidative stress and general cellular stress upon exposure. Here, we evaluated the ability of the ToxTracker assay to identify the hazardous properties and underlying mechanisms of a panel of metal oxide- and silver nanoparticles (NPs) as well as additional non-metallic materials (diesel, carbon nanotubes and quartz).

METHODS

The metal oxide- and silver nanoparticles were characterized in terms of agglomeration and ion release in cell medium (using photon cross correlation spectroscopy and inductively coupled plasma with optical emission spectroscopy, respectively) as well as acellular ROS production (DCFH-DA assay). Cellular uptake was investigated by means of transmission electron microscopy. GFP reporter induction and cytotoxicity of the NPs was simultaneously determined using flow cytometry, and genotoxicity was further tested using conventional assays (comet assay, γ-H2AX and RAD51 foci formation).

RESULTS

We show that the reporter cells were able to take up nanoparticles and, furthermore, that exposure to CuO, NiO and ZnO nanoparticles as well as to quartz resulted in activation of the oxidative stress reporter, although only at high cytotoxicity for ZnO. NiO NPs activated additionally a p53-associated cellular stress response, indicating additional reactive properties. Conventional assays for genotoxicity assessment confirmed the response observed in the ToxTracker assay. We show for CuO NPs that the induction of oxidative stress is likely the consequence of released Cu ions whereas the effect by NiO was related to the particles per se. The DNA replication stress-induced reporter, which is most strongly associated with carcinogenicity, was not activated by any of the tested nanoparticles.

CONCLUSIONS

We conclude that the ToxTracker reporter system can be used as a rapid mechanism-based tool for the identification of hazardous properties of metal oxide NPs. Furthermore, genotoxicity of metal oxide NPs seems to occur mainly via oxidative stress rather than direct DNA binding with subsequent replication stress.

Targeted uptake of folic acid-functionalized iron oxide nanoparticles by ovarian cancer cells in the presence but not in the absence of serum

Targeted delivery of nanoparticles to cells or tissues of interest is arguably the "holy grail" of nanomedicine. Using primary human macrophages and ovarian cancer cells, we evaluated the biocompatibility and specific targeting of folic acid (FA)-conjugated iron oxide nanoparticles with organic [poly(ethylene glycol), PEG] or inorganic (SiO2) intermediate surface coatings. Reduction of folate receptor-α expression using specific siRNA resulted in a significant decrease in cellular uptake of the SiO2-coated nanoparticles, but did not affect uptake of PEG-coated nanoparticles. Notably, specific (i.e. FA-dependent) uptake was observed only in the presence of serum proteins. The strategy presented here for receptor-mediated uptake of nanoparticles with pre-defined surface chemistry may enable targeting of nanoparticles for therapeutic and imaging applications. From the clinical editor: In this study the receptor specific uptake of folic acid-functionalized iron oxide nanoparticles was determined in ovarian cancer cells. It was found that the presence of serum proteins is an absolute requirement for the uptake of these nanoparticles. The described strategy for receptor-mediated uptake of nanoparticles with pre-defined surface chemistry may enable a better targeting of nanoparticles for additional therapeutic and imaging applications.