Biological and environmental surface interactions of nanomaterials: characterization, modeling, and prediction

Development of multiplex gold nanoparticles biosensors for ultrasensitive detection and genotyping of equine herpes viruses

Gold nanoparticles (GNPs) biosensors can detect low viral loads and differentiate between viruses types, enabling early diagnosis and effective disease management. In the present study, we developed GNPs biosensors with two different capping agent, citrate-GNPs biosensors and polyvinylpyrrolidone (PVP)-GNPs biosensors for detection of EHV-1 and EHV-4 in multiplex real time PCR (rPCR). Citrate-GNPs and PVP-GNPs biosensors can detect dilution 1010 of EHV-1 with mean Cycle threshold (Ct) 11.7 and 9.6, respectively and one copy as limit of detection, while citrate-GNPs and PVP-GNPs biosensors can detect dilution 1010 of EHV-4 with mean Ct 10.5 and 9.2, respectively and one copy as limit of detection. These findings were confirmed by testing 87 different clinical samples, 4 more samples were positive with multiplex GNPs biosensors rPCR than multiplex rPCR. Multiplex citrate-GNPs and PVP-GNPs biosensors for EHV-1 and EHV-4 are a significant breakthrough in the diagnosis of these virus types. These biosensors offer high sensitivity and specificity, allowing for the accurate detection of the target viruses at very low concentrations and improve the early detection of EHV-1 and EHV-4, leading to faster control of infected animals to prevent the spread of these viruses.

Exploring the Biomedical Applications of Biosynthesized Silver Nanoparticles Using Perilla frutescens Flavonoid Extract: Antibacterial, Antioxidant, and Cell Toxicity Properties against Colon Cancer Cells

The present study reports the biomimetic synthesis of silver nanoparticles (AgNPs) using a simple, cost effective and eco-friendly method. In this method, the flavonoid extract of Perilla frutescens (PFFE) was used as a bioreduction agent for the reduction of metallic silver into nanosilver, called P. frutescens flavonoid extract silver nanoparticles (PFFE-AgNPs). The Ultraviolet-Visible (UV-Vis) spectrum showed a characteristic absorption peak at 440 nm that confirmed the synthesis of PFFE-AgNPs. A Fourier transform infrared spectroscopic (FTIR) analysis of the PFFE-AgNPs revealed that flavonoids are involved in the bioreduction and capping processes. X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns confirmed the face-centered cubic (FCC) crystal structure of PFFE-AgNPs. A transmission electron microscopic (TEM) analysis indicated that the synthesized PFFE-AgNPs are 20 to 70 nm in size with spherical morphology and without any aggregation. Dynamic light scattering (DLS) studies showed that the average hydrodynamic size was 44 nm. A polydispersity index (PDI) of 0.321 denotes the monodispersed nature of PFFE-AgNPs. Further, a highly negative surface charge or zeta potential value (-30 mV) indicates the repulsion, non-aggregation, and stability of PFFE-AgNPs. PFFE-AgNPs showed cytotoxic effects against cancer cell lines, including human colon carcinoma (COLO205) and mouse melanoma (B16F10), with IC50 concentrations of 59.57 and 69.33 μg/mL, respectively. PFFE-AgNPs showed a significant inhibition of both Gram-positive (Listeria monocytogens and Enterococcus faecalis) and Gram-negative (Salmonella typhi and Acinetobacter baumannii) bacteria pathogens. PFFE-AgNPs exhibited in vitro antioxidant activity by quenching 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydrogen peroxide (H2O2) free radicals with IC50 values of 72.81 and 92.48 µg/mL, respectively. In this study, we also explained the plausible mechanisms of the biosynthesis, anticancer, and antibacterial effects of PFFE-AgNPs. Overall, these findings suggest that PFFE-AgNPs have potential as a multi-functional nanomaterial for biomedical applications, particularly in cancer therapy and infection control. However, it is important to note that further research is needed to determine the safety and efficacy of these nanoparticles in vivo, as well as to explore their potential in other areas of medicine.

Predicted Adsorption Affinity for Enteric Microbial Metabolites to Metal and Carbon Nanomaterials

Ingested nanomaterials are exposed to many metabolites that are produced, modified, or regulated by members of the enteric microbiota. The adsorption of these metabolites potentially affects the identity, fate, and biodistribution of nanomaterials passing the gastrointestinal tract. Here, we explore these interactions using in silico methods, focusing on a concise overview of 170 unique enteric microbial metabolites which we compiled from the literature. First, we construct quantitative structure–activity relationship (QSAR) models to predict their adsorption affinity to 13 metal nanomaterials, 5 carbon nanotubes, and 1 fullerene. The models could be applied to predict log k values for 60 metabolites and were particularly applicable to ‘phenolic, benzoyl and phenyl derivatives’, ‘tryptophan precursors and metabolites’, ‘short-chain fatty acids’, and ‘choline metabolites’. The correlations of these predictions to biological surface adsorption index descriptors indicated that hydrophobicity-driven interactions contribute most to the overall adsorption affinity, while hydrogen-bond interactions and polarity/polarizability-driven interactions differentiate the affinity to metal and carbon nanomaterials. Next, we use molecular dynamics (MD) simulations to obtain direct molecular information for a selection of vitamins that could not be assessed quantitatively using QSAR models. This showed how large and flexible metabolites can gain stability on the nanomaterial surface via conformational changes. Additionally, unconstrained MD simulations provided excellent support for the main interaction types identified by QSAR analysis. Combined, these results enable assessing the adsorption affinity for many enteric microbial metabolites quantitatively and support the qualitative assessment of an even larger set of complex and biologically relevant microbial metabolites to carbon and metal nanomaterials.

In vivo protein corona on nanoparticles: does the control of all material parameters orient the biological behavior?

Nanomaterials have a huge potential in research fields from nanomedicine to medical devices. However, surface modifications of nanoparticles (NPs) and thus of their physicochemical properties failed to predict their biological behavior. This requires investigating the "missing link" at the nano-bio interface. The protein corona (PC), the set of proteins binding to the NPs surface, plays a critical role in particle recognition by the innate immune system. Still, in vitro incubation offers a limited understanding of biological interactions and fails to explain the in vivo fate. To date, several reports explained the impact of PC in vitro but its applications in the clinical field have been very limited. Furthermore, PC is often considered as a biological barrier reducing the targeting efficiency of nano vehicles. But the protein binding can actually be controlled by altering PC both in vitro and in vivo. Analyzing PC in vivo could accordingly provide a deep understanding of its biological effect and speed up the transfer to clinical applications. This review demonstrates the need for clarifications on the effect of PC in vivo and the control of its behavior by changing its physicochemical properties. It unfolds the recent in vivo developments to understand mechanisms and challenges at the nano-bio interface. Finally, it reports recent advances in the in vivo PC to overcome and control the limitations of the in vitro PC by employing PC as a boosting resource to prolong the NPs half-life, to improve their formulations and thereby to increase its use for biomedical applications.

Effects of the surface polarity of nanomaterials on their interaction with complement protein gC1q

There are increasing studies about the biocompatibility of nanomaterials (NMs) as their applications in biomedicine become more widespread. The biocompatibility of NMs involves the recognition by the immune system including complement protein gC1q. In this work, the interaction of graphene oxide (GO) and self-assembled monolayer (SAM)-coated gold (111) surface with gC1q was studied by molecular dynamics (MD) simulations. The impacts of surface polarity of GO on its interaction with gC1q and the possible immune response were discussed by comparing the binding behavior of gC1q to the GO sheets with different oxidation degrees (i.e., C5O1(OH)1 and C20O1(OH)1). We find the ghB module of gC1q tends to bind to GO sheet (C5O1(OH)1) with strong surface polarity, as the ghB module forms more hydrogen bonds with this GO sheet. On the other hand, the ghC module of gC1q tends to bind to GO (C20O1(OH)1) with weak surface polarity, as the ghC module tends to form pi-pi stacking and stronger hydrophobic interaction with this GO sheet. Similar phenomena are also found in the adsorption of gC1q with SAM: ghC prefers to bind to hydrophobic CH3-SAM, and ghB prefers to bind to charged COO-SAM. The different binding modules of gC1q may result in different activation levels of complement system. Our findings suggest that the surface polarity of NMs regulates the interaction of NMs with gC1q and the subsequent immune response. In other words, the biocompatibility of NMs may be regulated by adjusting their surface polarity.

Dosimetry in vitro - exploring the sensitivity of deposited dose predictions vs. affinity, polydispersity, freeze-thawing, and analytical methods

Dose-response by in vitro testing is only valid if the fraction of the particle dose that deposits onto adherent cells is known. Modeling tools such as the 'distorted grid' (DG) code are common practices to predict that fraction. As another challenge, workflow efficiency depends on parallelized sample preparation, for which freeze-thaw protocols have been explored earlier, but not their implications on dosimetry. Here we assess the sensitivity of the DG code toward freeze-thaw protocols and variations in user-defined parameters, including the estimation of particle-cell affinity and determination of agglomerate size, which we measure by DLS or AUC. We challenge the sensitivity by materials of varying composition, surface functionalization, and size (TiO₂, CeO₂, BaSO₄, 2x Ag, 3x SiO₂). We found that the average effective density is robust, but the dose predictions by different approaches varied typically 2-fold and up to 10-fold; this uncertainty translates directly into the uncertainty of no-effect-concentrations. The use of standardized dispersion protocols increases the uncertainty in doses. The choice of a measurement method and minor details of the particle size distribution strongly influence the modeled dosimetry. Uncertainty is high for very well dispersed nanomaterials; since then, the assumed affinity of particles to cells has a decisive influence. Against this background, the modulation of deposited dose by freeze-thaw protocols is a minor factor that can be controlled by aligning the protocols of sample preparation. However, even then, the uncertainty of deposited doses must be considered when comparing the in vitro toxicity of different nanomaterials.

FTIR microspectroscopy revealed biochemical changes in liver and kidneys as a result of exposure to low dose of iron oxide nanoparticles

Iron oxide nanoparticles (IONPs) have biomedical and biotechnological applications in magnetic imaging, drug-delivery, magnetic separation and purification. The biocompatibility of such particles may be improved by covering them with coating. In presented paper the biochemical anomalies of liver and kidney occurring in animals exposed to d-mannitol-coated iron(III) oxide nanoparticles (M-IONPs) were examined with Fourier transform infrared (FTIR) microspectroscopy. The dose of IONPs used in the study was significantly lower than those used so far in other research. Liver and kidney tissue sections were analysed by chemical mapping of infrared absorption bands originating from proteins, lipids, compounds containing phosphate groups, cholesterol and cholesterol esters. Changes in content and/or structure of the selected biomolecules were evaluated by comparison of the results obtained for animals treated with M-IONPs with those from control group. Biochemical analysis of liver samples demonstrated a few M-IONPs induced anomalies in the organ, mostly concerning the relative content of the selected compounds. The biomolecular changes, following exposition to nanoparticles, were much more intense within the kidney tissue. Biochemical aberrations found in the organ samples indicated at increase of tissue density, anomalies in fatty acids structure as well as changes in relative content of lipids and proteins. The simultaneous accumulation of lipids, phosphate groups as well as cholesterol and cholesterol esters in kidneys of rats exposed to IONPs may indicate that the particles stimulated formation of lipid droplets within the organ.

Meta-Analysis of Nanoparticle Delivery to Tumors Using a Physiologically Based Pharmacokinetic Modeling and Simulation Approach

Numerous studies have engineered nanoparticles with different physicochemical properties to enhance the delivery efficiency to solid tumors, yet the mean and median delivery efficiencies are only 1.48% and 0.70% of the injected dose (%ID), respectively, according to a study using a nonphysiologically based modeling approach based on published data from 2005 to 2015. In this study, we used physiologically based pharmacokinetic (PBPK) models to analyze 376 data sets covering a wide range of nanomedicines published from 2005 to 2018 and found mean and median delivery efficiencies at the last sampling time point of 2.23% and 0.76%ID, respectively. Also, the mean and median delivery efficiencies were 2.24% and 0.76%ID at 24 h and were decreased to 1.23% and 0.35%ID at 168 h, respectively, after intravenous administration. While these delivery efficiencies appear to be higher than previous findings, they are still quite low and represent a critical barrier in the clinical translation of nanomedicines. We explored the potential causes of this poor delivery efficiency using the more mechanistic PBPK perspective applied to a subset of gold nanoparticles and found that low delivery efficiency was associated with low distribution and permeability coefficients at the tumor site (P < 0.01). We also demonstrate how PBPK modeling and simulation can be used as an effective tool to investigate tumor delivery efficiency of nanomedicines.

Oriented Immobilization on Gold Nanoparticles of a Recombinant Therapeutic Zymogen

Direct immobilization of functional proteins on gold nanoparticles (AuNPs) affects their structure and function. Changes may vary widely and range from strong inhibition to the enhancement of protein function. More often though the outcome of direct protein immobilization results in protein misfolding and the loss of protein activity. Additional complications arise when the protein being immobilized is a zymogen which requires and relies on additional protein-protein interactions to exert its function. Here we describe molecular design of a glutathione-S-transferase-Staphylokinase fusion protein (GST-SAK) and its conjugation to AuNPs. The multivalent AuNP-(GST-SAK)n complexes generated show plasminogen activation activity in vitro. The methods described are transferable and could be adapted for conjugation and functional analysis of other plasminogen activators, thrombolytic preparations or other functional enzymes.

An analytical approach for quantifying the influence of nanoparticle polydispersity on cellular delivered dose

Nanoparticles provide a promising approach for the targeted delivery of therapeutic, diagnostic and imaging agents in the body. However, it is not yet fully understood how the physico-chemical properties of the nanoparticles influence cellular association and uptake. Cellular association experiments are routinely performed in an effort to determine how nanoparticle properties impact the rate of nanoparticle–cell association. To compare experiments in a meaningful manner, the association data must be normalized by the amount of nanoparticles that arrive at the cells, a measure referred to as the delivered dose. The delivered dose is calculated from a model of nanoparticle transport through fluid. A standard assumption is that all nanoparticles within the population are monodisperse, namely the nanoparticles have the same physico-chemical properties. We present a semi-analytic solution to a modified model of nanoparticle transport that allows for the nanoparticle population to be polydisperse. This solution allows us to efficiently analyse the influence of polydispersity on the delivered dose. Combining characterization data obtained from a range of commonly used nanoparticles and our model, we find that the delivered dose changes by more than a factor of 2 if realistic amounts of polydispersity are considered.

SF-1 mediates reproductive toxicity induced by Cerium oxide nanoparticles in male mice

Background

Cerium oxide nanoparticles (CeO₂ NPs) have potential application for use in biomedical and in various consumer products. However, it is largely unclear whether CeO₂ NPs have effects on male reproductive function.

Methods

In this study, male mice were examined for toxicity, if any, following chronic oral administration of CeO₂ NPs for 32 days. In each animal, epididymides were examined for sperm motility and DNA integrity. Bloods were tested for testosterone levels. Testicular tissues were collected to determine the element Ce content, the daily sperm production (DSP), marker enzymes such as ACP, G6PD, γ-GT and SDH, mRNA expression levels of steroidogenesis genes Star, P450scc, P450c17, 3β-Hsd, and 17β-Hsd, as well as steroidogenic factor-1 (SF-1) gene/protein levels.

Results

The results showed that CeO₂ NPs (20 mg/kg and 40 mg/kg) increased the element Ce content in testis, the testis histopathological patterns and sperm DNA damage whereas decreased the testis weight, DSP and sperm motility. There were also remarkable reduction in testosterone levels and marker enzymes activities, down-regulated mRNA expression levels of several steroidogenesis genes such as Star, P450scc, P450c17, 3β-Hsd, and 17β-Hsd, as well as altered gene and protein expressions of SF-1.

Conclusion

These results reveal the male reproductive toxicity of chronic exposure of CeO₂ NPs in mice, hinting that the utilization of CeO₂ NPs need to be carefully evaluated about their potential reproductive toxicity on the human health.

Electronic supplementary material

The online version of this article (10.1186/s12951-019-0474-2) contains supplementary material, which is available to authorized users.

Physiologically based mathematical models of nanomaterials for regulatory toxicology: A review

The development of physiologically based (PB) models to support safety assessments in the field of nanotechnology has grown steadily during the last decade. This review reports on the availability of PB models for toxicokinetic (TK) and toxicodynamic (TD) processes, including in vitro and in vivo dosimetry models applied to manufactured nanomaterials (MNs). In addition to reporting on the state-of-the-art in the scientific literature concerning the availability of physiologically based kinetic (PBK) models, we evaluate their relevance for regulatory applications, mainly considering the EU REACH regulation. First, we performed a literature search to identify all available PBK models. Then, we systematically reported the content of the identified papers in a tailored template to build a consistent inventory, thereby supporting model comparison. We also described model availability for physiologically based dynamic (PBD) and in vitro and in vivo dosimetry models according to the same template. For completeness, a number of classical toxicokinetic (CTK) models were also included in the inventory. The review describes the PBK model landscape applied to MNs on the basis of the type of MNs covered by the models, their stated applicability domain, the type of (nano-specific) inputs required, and the type of outputs generated. We identify the main assumptions made during model development that may influence the uncertainty in the final assessment, and we assess the REACH relevance of the available models within each model category. Finally, we compare the state of PB model acceptance for chemicals and for MNs. In general, PB model acceptance is limited by the absence of standardised reporting formats, psychological factors such as the complexity of the models, and technical considerations such as lack of blood:tissue partitioning data for model calibration/validation.

Nanotechnology and multipotent adult progenitor cells in Reparative Medicine: therapeutic perspectives

The biology of stem cells is one of the most dynamic and promising fields of the biological sciences, since it is the basis for the development of organisms. Its biological complexity demands efforts from several lines of research aimed mainly at its therapeutic use. Nanotechnology has been emerging as a new field of study, which shows great potential in the treatment of various diseases. This new area of health has been called “Nanomedicine” or “Bionanotechnology”, which can be applied in Medicine by transport and drug delivery systems, robotic tools to be used in diagnostic and surgical processes, nanobiomaterials, gene therapies, nanobiomedical devices, among others. Because stem cells and Nanotechnology are two areas of extremely promising science, a new field of study, called “stem cell Nanotechnology”, has gradually emerged. In this, Nanotechnology is used to help the stem cells apply their therapeutic potential in the treatment, cure, and repair of the damaged tissues, in an effective and safe way. In this way, stem cell Nanotechnology has generated great interest, since it may result in significant contributions to Regenerative Medicine and tissue engineering. The present work aims to present the state-of-the-art regarding its therapeutic use in Human Medicine.

Minimum information reporting in bio-nano experimental literature

Studying the interactions between nanoengineered materials and biological systems plays a vital role in the development of biological applications of nanotechnology and the improvement of our fundamental understanding of the bio-nano interface. A significant barrier to progress in this multidisciplinary area is the variability of published literature with regards to characterizations performed and experimental details reported. Here, we suggest a 'minimum information standard' for experimental literature investigating bio-nano interactions. This standard consists of specific components to be reported, divided into three categories: material characterization, biological characterization and details of experimental protocols. Our intention is for these proposed standards to improve reproducibility, increase quantitative comparisons of bio-nano materials, and facilitate meta analyses and in silico modelling.

Gold nanoparticles with patterned surface monolayers for nanomedicine: current perspectives

Molecular self-assembly is a topic attracting intense scientific interest. Various strategies have been developed for construction of molecular aggregates with rationally designed properties, geometries, and dimensions that promise to provide solutions to both theoretical and practical problems in areas such as drug delivery, medical diagnostics, and biosensors, to name but a few. In this respect, gold nanoparticles covered with self-assembled monolayers presenting nanoscale surface patterns-typically patched, striped or Janus-like domains-represent an emerging field. These systems are particularly intriguing for use in bio-nanotechnology applications, as presence of such monolayers with three-dimensional (3D) morphology provides nanoparticles with surface-dependent properties that, in turn, affect their biological behavior. Comprehensive understanding of the physicochemical interactions occurring at the interface between these versatile nanomaterials and biological systems is therefore crucial to fully exploit their potential. This review aims to explore the current state of development of such patterned, self-assembled monolayer-protected gold nanoparticles, through step-by-step analysis of their conceptual design, synthetic procedures, predicted and determined surface characteristics, interactions with and performance in biological environments, and experimental and computational methods currently employed for their investigation.

NanoEHS beyond Toxicity - Focusing on Biocorona

The first phase of environmental health and safety of nanomaterials (nanoEHS) studies has been mainly focused on evidence-based investigations that probe the impact of nanoparticles, nanomaterials and nano-enabled products on biological and ecological systems. The integration of multiple disciplines, including colloidal science, nanomaterial science, chemistry, toxicology/immunology and environmental science, is necessary to understand the implications of nanotechnology for both human health and the environment. While strides have been made in connecting the physicochemical properties of nanomaterials with their hazard potential in tiered models, fundamental understanding of nano-biomolecular interactions and their implications for nanoEHS is largely absent from the literature. Research on nano-biomolecular interactions within the context of natural systems not only provides important clues for deciphering nanotoxicity and nanoparticle-induced pathology, but also presents vast new opportunities for screening beneficial material properties and designing greener products from bottom up. This review highlights new opportunities concerning nano-biomolecular interactions beyond the scope of toxicity.