Effects of the presence or absence of a protein corona on silica nanoparticle uptake and impact on cells

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.

Mesoporous Bioactive Glasses in Cancer Diagnosis and Therapy: Stimuli-Responsive, Toxicity, Immunogenicity, and Clinical Translation

Cancer is one of the top life-threatening dangers to the human survival, accounting for over 10 million deaths per year. Bioactive glasses have developed dramatically since their discovery 50 years ago, with applications that include therapeutics as well as diagnostics. A new system within the bioactive glass family, mesoporous bioactive glasses (MBGs), has evolved into a multifunctional platform, thanks to MBGs easy-to-functionalize nature and tailorable textural properties-surface area, pore size, and pore volume. Although MBGs have yet to meet their potential in tumor treatment and imaging in practice, recently research has shed light on the distinguished MBGs capabilities as promising theranostic systems for cancer imaging and therapy. This review presents research progress in the field of MBG applications in cancer diagnosis and therapy, including synthesis of MBGs, mechanistic overview of MBGs application in tumor diagnosis and drug monitoring, applications of MBGs in cancer therapy ( particularly, targeted delivery and stimuli-responsive nanoplatforms), and immunological profile of MBG-based nanodevices in reference to the development of novel cancer therapeutics.

Advances in genotoxicity of titanium dioxide nanoparticles in vivo and in vitro

Titanium dioxide nanoparticles (TiO₂ NPs) are currently one of the most widely used nanomaterials. Due to an increasing scope of applications, the exposure of humans to TiO₂ NP is inevitable, such as entering the body through the mouth with food additives or drugs, invading the damaged skin with cosmetics, and entering the body through the respiratory tract during the process of production and handling. Compared with TiO₂ coarse particles, TiO₂ NPs have stronger conductivity, reaction activity, photocatalysis, and permeability, which may lead to greater toxicity to organisms. Given that TiO₂ was classified as a category 2B carcinogen (possibly carcinogenic to humans), the genotoxicity of TiO₂ NPs has become the focus of attention. There have been a series of previous studies investigating the potential genotoxicity of TiO₂ NPs, but the existing research results are still controversial and difficult to conclude. More than half of studies have shown that TiO₂ NPs can cause genotoxicity, suggesting that TiO₂ NPs are likely to be genotoxic to humans. And the genotoxicity of TiO₂ NPs is closely related to the exposure concentration, mode and time, and experimental cells/animals as well as its physicochemical properties (crystal type, size, and shape). This review summarized the latest research progress of related genotoxic effects through in vivo studies and in vitro cell tests, hoping to provide ideas for the evaluation of TiO₂ NPs genotoxicity.

Ecotoxicological read-across models for predicting acute toxicity of freshly dispersed versus medium-aged NMs to Daphnia magna

Nanoinformatics models to predict the toxicity/ecotoxicity of nanomaterials (NMs) are urgently needed to support commercialization of nanotechnologies and allow grouping of NMs based on their physico-chemical and/or (eco)toxicological properties, to facilitate read-across of knowledge from data-rich NMs to data-poor ones. Here we present the first ecotoxicological read-across models for predicting NMs ecotoxicity, which were developed in accordance with ECHA's recommended strategy for grouping of NMs as a means to explore in silico the effects of a panel of freshly dispersed versus environmentally aged (in various media) Ag and TiO₂ NMs on the freshwater zooplankton Daphnia magna, a keystone species used in regulatory testing. The dataset used to develop the models consisted of dose-response data from 11 NMs (5 TiO₂ NMs of identical cores with different coatings, and 6 Ag NMs with different capping agents/coatings) each dispersed in three different media (a high hardness medium (HH Combo) and two representative river waters containing different amounts of natural organic matter (NOM) and having different ionic strengths), generated in accordance with the OECD 202 immobilization test. The experimental hypotheses being tested were (1) that the presence of NOM in the medium would reduce the toxicity of the NMs by forming an ecological corona, and (2) that environmental ageing of NMs reduces their toxicity compared to the freshly dispersed NMs irrespective of the medium composition (salt only or NOM-containing). As per the ECHA guidance, the NMs were grouped into two categories - freshly dispersed and 2-year-aged and explored in silico to identify the most important features driving the toxicity in each group. The final predictive models have been validated according to the OECD criteria and a QSAR model report form (QMRF) report included in the supplementary information to support adoption of the models for regulatory purposes.

Supramolecular organization and biological interaction of squalenoyl siRNA nanoparticles

Small interfering RNAs (siRNA) are attractive and powerful tools to inhibit the expression of a targeted gene. However, their extreme hydrophilicities combined with a negative charge and short plasma half-life counteract their use as therapeutics. Previously, we chemically linked siRNA to squalene (SQ) which self-assembled as nanoparticles (NPs) with pharmacological efficiency in cancers and recently in a hereditary neuropathy. In order to understand the siRNA-SQ NP assembly and fate once intravenously injected, the present study detailed characterization of siRNA-SQ NP structure and its interaction with serum components. From SAXS and SANS analysis, we propose that the siRNA-SQ bioconjugate self-assembled as 11-nm diameter supramolecular assemblies, which are connected one to another to form spherical nanoparticles of around 130-nm diameter. The siRNA-SQ NPs were stable in biological media and interacted with serum components, notably with albumin and LDL. The high specificity of siRNA to decrease or normalize gene expression and the high colloidal stability when encapsulated into squalene nanoparticles offer promising targeted therapy with wide applications for pathologies with gene expression dysregulation.

Bibliometric landscape of the researches on protein corona of nanoparticles

Unclear biological fate hampers the clinical translation of nanoparticles for biomedical uses. In recent years, it is documented that the formation of protein corona upon nanoparticles is a critical factor leading to the ambiguous biological fate. Efforts have been made to explore the protein corona forming behaviors on nanoparticles, and rearrangement of the relevant studies will help to understand the current trend of such a topic. In this work, the publications about protein corona of nanoparticles in Science Citation Index Expanded database of Web of Science from 2007 to 2020 (1417 in total) were analyzed in detail, and the bibliometrics landscape of them was showcased. The basic bibliometrics characteristics were summarized to provide an overall understanding. Citation analysis was performed to scrutinize the peer interests of these papers. The research hotspots in the field were evaluated, based on which some feasible topics for future studies were proposed. In general, the results demonstrated that protein corona of nanoparticles was a prospective research area, and had attracted global research interests. It was believed that this work could comprehensively highlight the bibliometrics landscape, inspire further exploitation on protein corona of nanoparticles, and ultimately promote the clinical translation of nanoparticles.

Modulating Osteoimmune Responses by Mesoporous Silica Nanoparticles

The immune response plays an important role in biomaterial-mediated osteogenesis. Nanomaterials may influence immune responses and thereby alter bone regeneration. Mesoporous silica nanoparticles (MSNs) have received much attention for drug delivery and bone regeneration. Recently, immunomodulatory effects of MSNs on osteogenesis have been reported. In this Review, we summarize the osteoimmunomodulation of MSNs, including the effects of MSN characteristics on immune cells and osteogenesis. Impacts of MSNs on immune cells vary according to nanoparticle properties, including surface topography and charge, particle size, and ion release. MSNs with suitable doses can inhibit inflammation and create an immune microenvironment beneficial for bone regeneration by activating immune cells and stimulating cytokine release. Further work is needed to explore and clarify the underlying mechanisms, including crosstalk between various types of immune cells and how to design MSNs to create a suitable immune environment for osteogenesis.

Correlating Corona Composition and Cell Uptake to Identify Proteins Affecting Nanoparticle Entry into Endothelial Cells

The formation of the biomolecule corona on the surface of nanoparticles upon exposure to biological fluids critically influences nanocarrier performance in drug delivery. It has been shown that in some cases corona proteins can mediate specific nanoparticle interactions with cell receptors. Within this context, in order to identify corona proteins affecting nanoparticle uptake, in this work, correlation analysis is performed between the corona composition of a panel of silica nanoparticles of different sizes and surface functionalities and their uptake in four endothelial cell types derived from different organs. In this way, proteins that correlate with increased or decreased uptake were identified, and their effects were validated by studying the uptake of nanoparticles coated with a single protein corona and competition studies in brain and liver endothelium. The results showed that precoating nanoparticles with histidine-rich glycoprotein (HRG) alone strongly decreased uptake in both liver and brain endothelium. Furthermore, our results suggested the involvement of the transferrin receptor in nanoparticle uptake in liver endothelium and redirection of the nanoparticles to other receptors with higher uptake efficiency when the transferrin receptor was blocked by free transferrin. These data suggested that changes in the cell microenvironment can also affect nanoparticle uptake and may lead to a different interaction site with nanoparticles, affecting their uptake efficiency. Overall, correlating the composition of the protein corona and nanoparticle uptake by cells allows for the identification of corona molecules that can be used to increase as well as to reduce nanoparticle uptake by cells.

Serum apolipoprotein A-I depletion is causative to silica nanoparticles-induced cardiovascular damage

The rapid development of nanotechnology has greatly benefited modern science and engineering and also led to an increased environmental exposure to nanoparticles (NPs). While recent research has established a correlation between the exposure of NPs and cardiovascular diseases, the intrinsic mechanisms of such a connection remain unclear. Inhaled NPs can penetrate the air-blood barrier from the lung to systemic circulation, thereby intruding the cardiovascular system and generating cardiotoxic effects. In this study, on-site cardiovascular damage was observed in mice upon respiratory exposure of silica nanoparticles (SiNPs), and the corresponding mechanism was investigated by focusing on the interaction of SiNPs and their encountered biomacromolecules en route. SiNPs were found to collect a significant amount of apolipoprotein A-I (Apo A-I) from the blood, in particular when the SiNPs were preadsorbed with pulmonary surfactants. While the adsorbed Apo A-I ameliorated the cytotoxic and proinflammatory effects of SiNPs, the protein was eliminated from the blood upon clearance of the NPs. However, supplementation of Apo A-I mimic peptide mitigated the atherosclerotic lesion induced by SiNPs. In addition, we found a further declined plasma Apo A-I level in clinical silicosis patients than coronary heart disease patients, suggesting clearance of SiNPs sequestered Apo A-I to compromise the coronal protein's regular biological functions. Together, this study has provided evidence that the protein corona of SiNPs acquired in the blood depletes Apo A-I, a biomarker for prediction of cardiovascular diseases, which gives rise to unexpected toxic effects of the nanoparticles.

Role of proteins in the biosynthesis and functioning of metallic nanoparticles

Proteins are known to play important roles in the biosynthesis of metallic nanoparticles (NPs), which are biological substitutes for conventionally used chemical capping and stabilizing agents. When a pristine nanoparticle comes in contact with a biological media or system, a bimolecular layer is formed on the surface of the nanoparticle and is primarily composed of proteins. The role of proteins in the biosynthesis and further uptake, translocation, and bio-recognition of nanoparticles is documented in the literature. But, a complete understanding has not been achieved concerning the mechanism for protein-mediated nanoparticle biosynthesis and the role proteins play in the interaction and recognition of nanoparticles, aiding its uptake and assimilation into the biological system. This review critically evaluates the knowledge and gaps in the protein-mediated biosynthesis of nanoparticles. In particular, we review the role of proteins in multiple facets of metallic nanoparticle biosynthesis, the interaction of proteins with metallic nanoparticles for recognition and interaction with cells, and the toxic potential of protein-nanoparticle complexes when presented to the cell.

Formation and biological effects of protein corona for food-related nanoparticles

The rapid development of nanoscience and nanoengineering provides new perspectives on the composition of food materials, and has great potential for food biology research and applications. The use of nanoparticle additives and the discovery of endogenous nanoparticles in food make it important to elucidate in vivo safety of nanomaterials. Nanoparticles will spontaneously adsorb proteins during transporting in blood and a protein corona can be formed on the nanoparticle surface inside the human body. Protein corona affects the physicochemical properties of nanoparticles and the structure and function of proteins, which in turn affects a series of biological reactions. This article reviewed basic information about protein corona of food-related nanoparticles, elucidated the influence of protein corona on nanoparticles properties and protein structure and function, and discussed the effect of protein corona on nanoparticles in vivo. The effects of protein corona on nanoparticles transport, cellular uptake, cytotoxicity, and immune response were reviewed, and the reasons for these effects were also discussed. Finally, future research perspectives for food protein corona were proposed. Protein corona gives food nanoparticles a new identity, which makes proteins bound to nanoparticles undergo structural transformations that affect their recognition by receptors in vivo. It can have positive or negative impacts on cellular uptake and toxicity of nanoparticles and even trigger immune responses. Understanding the effects of protein corona have potential in evaluating the fate of the food-related nanoparticles, providing physicochemical and biological information about the interaction between proteins and foodborne nanoparticles. The review article will help to evaluate the safety of protein coronas formed on nanoparticles in food, and may provide fundamental information for understanding and controlling nanotoxicity.

Targeting the Inside of Cells with Biologicals: Chemicals as a Delivery Strategy

Delivering macromolecules into the cytosol or nucleus is possible in vitro for DNA, RNA and proteins, but translation for clinical use has been limited. Therapeutic delivery of macromolecules into cells requires overcoming substantially higher barriers compared to the use of small molecule drugs or proteins in the extracellular space. Breakthroughs like DNA delivery for approved gene therapies and RNA delivery for silencing of genes (patisiran, ONPATTRO^®, Alnylam Pharmaceuticals, Cambridge, MA, USA) or for vaccination such as the RNA-based coronavirus disease 2019 (COVID-19) vaccines demonstrated the feasibility of using macromolecules inside cells for therapy. Chemical carriers are part of the reason why these novel RNA-based therapeutics possess sufficient efficacy for their clinical application. A clear advantage of synthetic chemicals as carriers for macromolecule delivery is their favourable properties with respect to production and storage compared to more bioinspired vehicles like viral vectors or more complex drugs like cellular therapies. If biologicals can be applied to intracellular targets, the druggable space is substantially broadened by circumventing the limited utility of small molecules for blocking protein–protein interactions and the limitation of protein-based drugs to the extracellular space. An in depth understanding of the macromolecular cargo types, carrier types and the cell biology of delivery is crucial for optimal application and further development of biologicals inside cells. Basic mechanistic principles of the molecular and cell biological aspects of cytosolic/nuclear delivery of macromolecules, with particular consideration of protein delivery, are reviewed here. The efficiency of macromolecule delivery and applications in research and therapy are highlighted.

Sources of variability in nanoparticle uptake by cells

Understanding how nano-sized objects are taken up by cells is important for applications within medicine (nanomedicine), as well as to avoid unforeseen hazard due to nanotechnology (nanosafety). Even within the same cell population, one typically observes a large cell-to-cell variability in nanoparticle uptake, raising the question of the underlying cause(s). Here we investigate cell-to-cell variability in polystyrene nanoparticle uptake by HeLa cells, with generalisations of the results to silica nanoparticles and liposomes, as well as to A549 and primary human umbilical vein endothelial cells. We show that uptake of nanoparticles is correlated with cell size within a cell population, thereby reproducing and generalising previous reports highlighting the role of cell size in nanoparticle uptake. By repeatedly isolating (using fluorescence-activated cell sorting) the cells that take up the most and least nanoparticles, respectively, and performing RNA sequencing on these cells separately, we examine the underlying gene expression that contributes to high and low polystyrene nanoparticle accumulation in HeLa cells. We can thereby show that cell size is not the sole driver of cell-to-cell variability, but that other cellular characteristics also play a role. In contrast to cell size, these characteristics are more specific to the object (nanoparticle or protein) being taken up, but are nevertheless highly heterogeneous, complicating their detailed identification. Overall, our results highlight the complexity underlying the cellular features that determine nanoparticle uptake propensity.

Bridging the academic-industrial gap: application of an oxygen and pH sensor-integrated lab-on-a-chip in nanotoxicology

Translation of advanced cell-based assays exhibiting a higher degree of automation, miniaturization, and integration of complementary sensing functions is mainly limited by the development of industrial-relevant prototypes that can be readily produced in larger volumes. Despite the increasing number of academic publications in recent years, the manufacturability of these microfluidic cell cultures systems is largely ignored, thus severely restricting their implementation in routine toxicological applications. We have developed a dual-sensor integrated microfluidic cell analysis platform using industrial specifications, materials, and fabrication methods to conduct risk assessment studies of engineered nanoparticles to overcome this academic-industrial gap. Non-invasive and time-resolved monitoring of cellular oxygen uptake and metabolic activity (pH) in the absence and presence of nanoparticle exposure is accomplished by integrating optical sensor spots into a cyclic olefin copolymer (COC)-based microfluidic platform. Results of our nanotoxicological study, including two physiological cell barriers that are essential in the protection from exogenous factors, the intestine (Caco-2) and the vasculature (HUVECs) showed that the assessment of the cells' total energy metabolism is ideally suited to rapidly detect cytotoxicities. Additional viability assay verification using state-of-the-art dye exclusion assays for nanotoxicology demonstrated the similarity and comparability of our results, thus highlighting the benefits of employing a compact and cost-efficient microfluidic dual-sensor platform as a pre-screening tool in nanomaterial risk assessment and as a rapid quality control measure in medium to high-throughput settings.

Plasmonic-Assisted Thermocyclizations in Living Cells Using Metal-Organic Framework Based Nanoreactors

We describe a microporous plasmonic nanoreactor to carry out designed near-infrared (NIR)-driven photothermal cyclizations inside living cells. As a proof of concept, we chose an intramolecular cyclization that is based on the nucleophilic attack of a pyridine onto an electrophilic carbon, a process that requires high activation energies and is typically achieved in bulk solution by heating at ∼90 °C. The core-shell nanoreactor (NR) has been designed to include a gold nanostar core, which is embedded within a metal-organic framework (MOF) based on a polymer-stabilized zeolitic imidazole framework-8 (ZIF-8). Once accumulated inside living cells, the MOF-based cloak of NRs allows an efficient diffusion of reactants into the plasmonic chamber, where they undergo the transformation upon near-IR illumination. The photothermal-driven reaction enables the intracellular generation of cyclic fluorescent products that can be tracked using fluorescence microscopy. The strategy may find different type of applications, such as for the spatio-temporal activation of prodrugs.

Mechanisms of Silver Nanoparticle Uptake by Embryonic Zebrafish Cells

Evaluation of the uptake pathways in cells during exposure to nanoparticles (NPs) is key for risk assessment and the development of safer nanomaterials, as the internalisation and fate of NPs is linked to their toxicity and mode of action. Here, we determined the uptake mechanisms activated during the internalisation of 10, 30, and 100 nm AgNPs by embryonic zebrafish cells (ZF4). The uptake results demonstrated an NP size- and time-dependent uptake, showing the highest total silver uptake for the smallest AgNP (10 nm) at the lowest exposure concentration (2.5 μg/mL) after 2 h, while after 24 h, the highest exposure concentration (10 μg/mL) of the 10 nm AgNPs revealed the highest cellular load at 8 pg/cell. Inhibition of the caveolae, clathrin, and macropinocytosis endocytic pathways by pharmaceutical inhibitors (genistein, chlorpromazine, and wortmannin respectively) revealed that uptake was mainly via macropinocytosis for the 10 nm AgNPs and via the caveolae-mediated pathway for the 30 and 100 nm AgNPs. The induction of autophagy was also strongly related to the NP size, showing the highest percentage of induction for the 10 nm (around 3%) compared to naive cells, suggesting that autophagy can be activated along with endocytosis to deal with exposure to NPs. TEM imaging revealed the distribution of NPs across the cytoplasm inside intracellular vesicles. An increase in Early Endosome formation (EE) was observed for the 30 and 100 nm sizes, whereas the 10 nm AgNPs disrupted the activity of EE. The data supports the establishment of adverse outcome pathways by increasing knowledge on the link between a molecular initiating event such as receptor-mediated endocytosis and an adverse outcome, as well as supporting the reduction of animal testing by using alternative testing models, such as fish cell lines.

Data-Driven Modeling of the Cellular Pharmacokinetics of Degradable Chitosan-Based Nanoparticles

Nanoparticle drug delivery vehicles introduce multiple pharmacokinetic processes, with the delivery, accumulation, and stability of the therapeutic molecule influenced by nanoscale processes. Therefore, considering the complexity of the multiple interactions, the use of data-driven models has critical importance in understanding the interplay between controlling processes. We demonstrate data simulation techniques to reproduce the time-dependent dose of trimethyl chitosan nanoparticles in an ND7/23 neuronal cell line, used as an in vitro model of native peripheral sensory neurons. Derived analytical expressions of the mean dose per cell accurately capture the pharmacokinetics by including a declining delivery rate and an intracellular particle degradation process. Comparison with experiment indicates a supply time constant, τ = 2 h. and a degradation rate constant, b = 0.71 h⁻¹. Modeling the dose heterogeneity uses simulated data distributions, with time dependence incorporated by transforming data-bin values. The simulations mimic the dynamic nature of cell-to-cell dose variation and explain the observed trend of increasing numbers of high-dose cells at early time points, followed by a shift in distribution peak to lower dose between 4 to 8 h and a static dose profile beyond 8 h.

Fate of CdSe/ZnS quantum dots in cells: Endocytosis, translocation and exocytosis

Semiconductor quantum dots (QDs) have been extensively explored for extensive bioapplications, yet their cellular fate, especially exocytosis, has not been thoroughly investigated. Herein, we systematically investigated the whole cellular process from the endocytosis, intercellular trafficking, to the exocytosis of a typical QD, core/shell CdSe/ZnS QD. Using confocal laser scanning microscopy and flow cytometry, and after carefully eliminating the effect of cell division, we found that the QDs were internalized by HeLa cells with a time-, dose-, and serum-dependent manner. The cellular uptake was inhibited by serum, but eventually peaked after 4-6 h incubation with or without serum. The primary endocytosis pathway was clathrin-mediated, and actin- and microtubule-dependent in the medium with serum, while the caveolae-mediated endocytosis and macropinocytosis were more important for the QDs in the serum-free medium. Inside cells, most QDs distributed in lysosomes, and some entered mitochondria, endoplasmic reticulum, and Golgi apparatus. The translocation of the QDs from other organelles to Golgi apparatus was observed. The exocytosis of QDs was faster than the endocytosis, reaching the maximum in about one hour after cultured in fresh culture medium, with around 60% of the internalized QDs remained undischarged. The exocytosis process was energy- and actin-dependent, and the lysosome exocytosis and endoplasmic reticulum/Golgi pathway were the main routes. This study provides a full picture of behavior and fate of QDs in cells, which may facilitate the design of ideal QDs applied in biomedical and other fields.

Nanosystems and exosomes as future approaches in treating multiple sclerosis

Multiple sclerosis (MS) is an immune-mediated demyelinating disease of the central nervous system which leads to neurological dysfunctions and severe disabilities. MS pathology is characterised by damage of the blood-brain barrier and infiltration of autoreactive T cells that overactivate glial cells, thereby initiating neuroinflammation accompanied by the formation of demyelinating plaques and neurodegeneration. Clinical deficits in this multifactorial disease depend on the progression of myelin loss, the stage of inflammation, the status of axons and the activity of oligodendrocyte precursor cells (OPCs). Despite significant progress in the treatment of MS, current therapies remain limited and new approaches are highly desirable. Nanosystems based on liposomes and nanoparticles are among some of the more noteworthy therapeutic strategies being investigated. Applications of nanosystems alone or as drug carriers in animal models of MS have been found to successfully alleviate the symptoms of the disease and exert anti-inflammatory potential. Exosomes are a specific type of nanosystem based on nanometre-sized extracellular vesicles released by different cells which exhibit important healing features. Exosomes contain an array of anti-inflammatory and neuroprotective agents which may contribute to modulation of the immune system as well as promoting remyelination and tissue repair. In this review, opportunities to use nanosystems against progression of MS will be discussed in context of cell-specific pathologies associated with MS.

The need for robust characterization of nanomaterials for nanomedicine applications

Robust and precise characterization of the interactions between nanoengineered materials and biosystems is vital for the development of safe, efficient diagnostic and therapeutic nanomedicines. This comment discusses the key aspects of nanoparticle characteristics affecting the interpretation of nano-bio interface data.

In Planta Nanosensors: Understanding Biocorona Formation for Functional Design

Climate change and population growth are straining agricultural output. To counter these changes and meet the growing demand for food and energy, the monitoring and engineering of crops are becoming increasingly necessary. Nanoparticle-based sensors have emerged in recent years as new tools to advance agricultural practices. As these nanoparticle-based sensors enter and travel through the complex biofluids within plants, biomolecules including proteins, metabolites, lipids, and carbohydrates adsorb onto the nanoparticle surfaces, forming a coating known as the "bio-corona". Understanding these nanoparticle-biomolecule interactions that govern nanosensor function in plants will be essential to successfully develop and translate nanoparticle-based sensors into broader agricultural practice.

Dopamine Receptor-Mediated Binding and Cellular Uptake of Polydopamine-Coated Nanoparticles

Polydopamine (PDA)-coated nanoparticles (NPs) are emerging carriers of therapeutic agents for nanomedicine applications due to their biocompatibility and abundant entry to various cell types, yet it remains unknown whether their cellular entry engages cell-surface receptors. As monomeric dopamine (DA) is an endogenous ligand of dopamine receptor and raw ingredient of PDA, we elucidate the interaction between polyethylene glycol-stabilized, PDA-coated gold NPs (Au@PDA@PEG NPs) and dopamine receptors, particularly D2 (D2DR). After proving the binding of Au@PDA@PEG NPs to recombinant and cellular D2DR, we employ antibody blocking, gene knockdown, and gene overexpression to establish the role of D2DR in the cellular uptake of Au@PDA@PEG NPs in vitro. By preparing a series of PEG-coated AuNPs that contain different structural analogues of DA (Au@PEG-X NPs), we demonstrate that catechol and amine groups collectively enhance the binding of NPs to D2DR and their cellular uptake. By intravenously injecting Au@PDA@PEG NPs to Balb/c mice, we reveal their in vivo binding to D2DR in the liver by competitive inhibition and immunohistochemistry together with their preferential association to D2DR-rich resident Kupffer cells by flow cytometry, a result consistent with the profuse expression of D2DR by resident Kupffer cells. Catechol and amine groups jointly contribute to the preferential association of NPs to D2DR-rich Kupffer cells. Our data highlight the importance of D2DR expression and DA-related functional groups in mediating the cell-nano interactions of PDA-based nanomedicines.

Nanotargeting of Resistant Infections with a Special Emphasis on the Biofilm Landscape

Bacterial resistance to antimicrobial compounds is a growing concern in medical and public health circles. Overcoming the adaptable and duplicative resistance mechanisms of bacteria requires chemistry-based approaches. Engineered nanoparticles (NPs) now offer unique advantages toward this effort. However, most in situ infections (in humans) occur as attached biofilms enveloped in a protective surrounding matrix of extracellular polymers, where survival of microbial cells is enhanced. This presents special considerations in the design and deployment of antimicrobials. Here, we review recent efforts to combat resistant bacterial strains using NPs and, then, explore how NP surfaces may be specifically engineered to enhance the potency and delivery of antimicrobial compounds. Special NP-engineering challenges in the design of NPs must be overcome to penetrate the inherent protective barriers of the biofilm and to successfully deliver antimicrobials to bacterial cells. Future challenges are discussed in the development of new antibiotics and their mechanisms of action and targeted delivery via NPs.

Citrate-Coated Superparamagnetic Iron Oxide Nanoparticles Enable a Stable Non-Spilling Loading of T Cells and Their Magnetic Accumulation

T cell infiltration into a tumor is associated with a good clinical prognosis of the patient and adoptive T cell therapy can increase anti-tumor immune responses. However, immune cells are often excluded from tumor infiltration and can lack activation due to the immune-suppressive tumor microenvironment. To make T cells controllable by external forces, we loaded primary human CD3+ T cells with citrate-coated superparamagnetic iron oxide nanoparticles (SPIONs). Since the efficacy of magnetic targeting depends on the amount of SPION loading, we investigated how experimental conditions influence nanoparticle uptake and viability of cells. We found that loading in the presence of serum improved both the colloidal stability of SPIONs and viability of T cells, whereas stimulation with CD3/CD28/CD2 and IL-2 did not influence nanoparticle uptake. Furthermore, SPION loading did not impair cytokine secretion after polyclonal stimulation. We finally achieved 1.4 pg iron loading per cell, which was both located intracellularly in vesicles and bound to the plasma membrane. Importantly, nanoparticles did not spill over to non-loaded cells. Since SPION-loading enabled efficient magnetic accumulation of T cells in vitro under dynamic conditions, we conclude that this might be a good starting point for the investigation of in vivo delivery of immune cells.

Effect of amino acid composition of elastin-like polypeptide nanoparticles on nonspecific protein adsorption, macrophage cell viability and phagocytosis

Development of elastin-like polypeptide (ELP) biomaterials is widespread, but information critical for clinical deployment is limited, with biocompatibility studies focused on a narrow cross-section of ELP sequences. Macrophages can impair biomaterial systems by degrading or isolating the biomaterial and by activating additional immune functions. Their phagocytic response will reveal early immune biocompatibility of ELP nanoparticles (NPs). This study examines that response, induced by the adsorbed protein corona, as a function of ELP guest amino acid, chain length and NP diameter. The breadth of proteins adsorbed to ELP NPs varied, with valine-containing ELP NPs adsorbing fewer types of proteins than leucine-containing constructs. Particle diameter was also a factor, with smaller leucine-containing ELP NPs adsorbing the broadest range of proteins. Macrophage viability was unaffected by the ELP NPs, and their phagocytic capabilities were unimpeded except when incubated with a 500 nm valine-containing 40-mer. This NP significantly decreased the phagocytic capacity of macrophages relative to the control and to a corresponding 500 nm leucine-containing 40-mer. NP size and the proportion of opsonin to dysopsonin proteins likely influenced this outcome. These results suggest that certain combinations of ELP sequence and particle size can result in an adsorbed protein corona, which may hinder macrophage function.

Interaction of nanoplastics with extracellular polymeric substances (EPS) in the aquatic environment: A special reference to eco-corona formation and associated impacts

Nanoplastics (NPs) are plastic particles with sizes ranging between 1 and 1000 nm, exhibiting exceptional qualities such as large surface area, lightweight, durability; therefore, are widely used in cosmetics, paints, electronics, etc. NPs are inevitability released into the aquatic environment where they tend to interact with both, the extracellular polymeric substances (EPS) and other fractions of natural organic matter (NOM), respectively secreted by organisms (e.g., DNA, proteins, and carbohydrates) and degradation byproducts of organic materials (e.g., humic acid and fulvic acid) fluxed into the water bodies. These biomolecules robustly encapsulate NPs to develop an eco-corona layer that alters not only the physicochemical properties but also the fate, bioreactivity, and ecological impacts of NPs. Therefore, this review summarized the documented studies highlighting the eco-corona formation on NPs and associated ecological implications in the aquatic environment. After presenting the precise background information on the occurrence of NPs and EPS in the aquatic environment, we demonstrated the basic difference between eco-corona and bio-corona formation. The reviewed studies showed that the eco-corona formed on NPs have varying sizes and composition, mainly depending on the properties of parent biomolecules, characteristics of NPs, and physicochemical parameters of the aquatic environment. Further, the potential methods for characterization and quantification of eco-corona and its composition have been also highlighted. Moreover, the ecological implications (both toxic and non-toxic) of eco-corona formation on NPs in marine and freshwater environments have been also summarized. Last but not the least, challenges and future research directions are also given, e.g., conducting field studies on eco-corona formation in the aquatic environment, optimizing methods for its characterization and quantification, and considering eco-corona concept in the future toxicity studies on NPs. Finally, understanding eco-corona formation will be critical to unveil the complex NP interactions occurring in natural aquatic systems.

A Focus on "Bio" in Bio-Nanoscience: The Impact of Biological Factors on Nanomaterial Interactions

Bio-nanoscience research encompasses studies on the interactions of nanomaterials with biological structures or what is commonly referred to as the biointerface. Fundamental studies on the influence of nanomaterial properties, including size, shape, composition, and charge, on the interaction with the biointerface have been central in bio-nanoscience to assess nanomaterial efficacy and safety for a range of biomedical applications. However, the state of the cells, tissues, or biological models can also influence the behavior of nanomaterials at the biointerface and their intracellular processing. Focusing on the "bio" in bio-nano, this review discusses the impact of biological properties at the cellular, tissue, and whole organism level that influences nanomaterial behavior, including cell type, cell cycle, tumor physiology, and disease states. Understanding how the biological factors can be addressed or exploited to enhance nanomaterial accumulation and uptake can guide the design of better and suitable models to improve the outcomes of materials in nanomedicine.

Interplay between nanomedicine and protein corona

Nanomedicine is recognized as a promising agent for diverse biomedical applications; however, its safety and efficiency in clinical practice remains to be enhanced. A priority issue is the protein corona (PC), which imparts unique biological identities to prototype and determines the actual biological functions in biological fluids. Decades of work has already illuminated abundant considerations that influence the composition of the protein corona. Thereinto, the physical assets of nanomedicines (e.g., size and shape, surface properties, nanomaterials) and the biological environment collectively play fundamental roles in shaping the PC, including the types and quantities of plasma proteins. The properties of nanomedicines are dependent on certain factors. This review aims to explore the applications of nanomedicines by regulating their interplay with PC.

Eco-Interactions of Engineered Nanomaterials in the Marine Environment: Towards an Eco-Design Framework

Marine nano-ecotoxicology has emerged with the purpose to assess the environmental risks associated with engineered nanomaterials (ENMs) among contaminants of emerging concerns entering the marine environment. ENMs’ massive production and integration in everyday life applications, associated with their peculiar physical chemical features, including high biological reactivity, have imposed a pressing need to shed light on risk for humans and the environment. Environmental safety assessment, known as ecosafety, has thus become mandatory with the perspective to develop a more holistic exposure scenario and understand biological effects. Here, we review the current knowledge on behavior and impact of ENMs which end up in the marine environment. A focus on titanium dioxide (n-TiO₂) and silver nanoparticles (AgNPs), among metal-based ENMs massively used in commercial products, and polymeric NPs as polystyrene (PS), largely adopted as proxy for nanoplastics, is made. ENMs eco-interactions with chemical molecules including (bio)natural ones and anthropogenic pollutants, forming eco- and bio-coronas and link with their uptake and toxicity in marine organisms are discussed. An ecologically based design strategy (eco-design) is proposed to support the development of new ENMs, including those for environmental applications (e.g., nanoremediation), by balancing their effectiveness with no associated risk for marine organisms and humans.

Toward the Specificity of Bare Nanomaterial Surfaces for Protein Corona Formation

Aiming at creating smart nanomaterials for biomedical applications, nanotechnology aspires to develop a new generation of nanomaterials with the ability to recognize different biological components in a complex environment. It is common opinion that nanomaterials must be coated with organic or inorganic layers as a mandatory prerequisite for applications in biological systems. Thus, it is the nanomaterial surface coating that predominantly controls the nanomaterial fate in the biological environment. In the last decades, interdisciplinary studies involving not only life sciences, but all branches of scientific research, provided hints for obtaining uncoated inorganic materials able to interact with biological systems with high complexity and selectivity. Herein, the fragmentary literature on the interactions between bare abiotic materials and biological components is reviewed. Moreover, the most relevant examples of selective binding and the conceptualization of the general principles behind recognition mechanisms were provided. Nanoparticle features, such as crystalline facets, density and distribution of surface chemical groups, and surface roughness and topography were encompassed for deepening the comprehension of the general concept of recognition patterns.

Biodegradable and biocompatible graphene-based scaffolds for functional neural tissue engineering: A strategy approach using dental pulp stem cells and biomaterials

Neural tissue engineering aims to restore the function of nervous system tissues using biocompatible cell-seeded scaffolds. Graphene-based scaffolds combined with stem cells deserve special attention to enhance tissue regeneration in a controlled manner. However, it is believed that minor changes in scaffold biomaterial composition, internal porous structure, and physicochemical properties can impact cellular growth and adhesion. The current work aims to investigate in vitro biological effects of three-dimensional (3D) graphene oxide (GO)/sodium alginate (GOSA) and reduced GOSA (RGOSA) scaffolds on dental pulp stem cells (DPSCs) in terms of cell viability and cytotoxicity. Herein, the effects of the 3D scaffolds, coating conditions, and serum supplementation on DPSCs functions are explored extensively. Biodegradation analysis revealed that the addition of GO enhanced the degradation rate of composite scaffolds. Compared to the 2D surface, the cell viability of 3D scaffolds was higher (p < 0.0001), highlighting the optimal initial cell adhesion to the scaffold surface and cell migration through pores. Moreover, the cytotoxicity study indicated that the incorporation of graphene supported higher DPSCs viability. It is also shown that when the mean pore size of the scaffold increases, DPSCs activity decreases. In terms of coating conditions, poly- l-lysine was the most robust coating reagent that improved cell-scaffold adherence and DPSCs metabolism activity. The cytotoxicity of GO-based scaffolds showed that DPSCs can be seeded in serum-free media without cytotoxic effects. This is critical for human translation as cellular transplants are typically serum-free. These findings suggest that proposed 3D GO-based scaffolds have favorable effects on the biological responses of DPSCs.

Dynamic interactions and intracellular fate of label-free, thin graphene oxide sheets within mammalian cells: role of lateral sheet size

Graphene oxide (GO) holds great potential for biomedical applications, however fundamental understanding of the way it interacts with biological systems is still lacking even though it is essential for successful clinical translation. In this study, we exploit intrinsic fluorescent properties of thin GO sheets to establish the relationship between lateral dimensions of the material, its cellular uptake mechanisms and intracellular fate over time. Label-free GO with distinct lateral dimensions, small (s-GO) and ultra-small (us-GO) were thoroughly characterised both in water and in biologically relevant cell culture medium. Interactions of the material with a range of non-phagocytic mammalian cell lines (BEAS-2B, NIH/3T3, HaCaT, 293T) were studied using a combination of complementary analytical techniques (confocal microscopy, flow cytometry and TEM). The uptake mechanism was initially interrogated using a range of pharmaceutical inhibitors and validated using polystyrene beads of different diameters (0.1 and 1 μm). Subsequently, RNA-Seq was used to follow the changes in the uptake mechanism used to internalize s-GO flakes over time. Regardless of lateral dimensions, both types of GO were found to interact with the plasma membrane and to be internalized by a panel of cell lines studied. However, s-GO was internalized mainly via macropinocytosis while us-GO was mainly internalized via clathrin- and caveolae-mediated endocytosis. Importantly, we report the shift from macropinocytosis to clathrin-dependent endocytosis in the uptake of s-GO at 24 h, mediated by upregulation of mTORC1/2 pathway. Finally, we show that both s-GO and us-GO terminate in lysosomal compartments for up to 48 h. Our results offer an insight into the mechanism of interaction of GO with non-phagocytic cell lines over time that can be exploited for the design of biomedically-applicable 2D transport systems.

SPIONs and magnetic hybrid materials: Synthesis, toxicology and biomedical applications

In the past decades, a wide variety of different superparamagnetic iron oxide nanoparticles (SPIONs) have been synthesized. Due to their unique properties, such as big surface-to-volume ratio, superparamagnetism and comparatively low toxicity, they are principally well suited for many different technical and biomedical applications. Meanwhile, there are a numerous synthesis methods for SPIONs, but high requirements for biocompatibility have so far delayed a successful translation into the clinic. Moreover, depending on the planned application, such as for imaging, magnetic drug targeting, hyperthermia or for hybrid materials intended for regenerative medicine, specific physicochemical and biological properties are inevitable. Since a summary of all existing SPION systems, their properties and application is far too extensive, this review reports on selected methods for SPION synthesis, their biocompatibility and biomedical applications.

Cellular interactions with polystyrene nanoplastics-The role of particle size and protein corona

Plastic waste is ubiquitously spread across the world and its smaller analogs-microplastics and nanoplastics-raise particular health concerns. While biological impacts of microplastics and nanoplastics have been actively studied, the chemical and biological bases for the adverse effects are sought after. This work explores contributory factors by combining results from in vitro and model mammalian membrane experimentation to assess the outcome of cell/nanoplastic interactions in molecular detail, inspecting the individual contribution of nanoplastics and different types of protein coronae. The in vitro study showed mild cytotoxicity and cellular uptake of polystyrene (PS) nanoplastics, with no clear trend based on nanoplastic size (20 and 200 nm) or surface charge. In contrast, a nanoplastic size-dependency on bilayer disruption was observed in the model system. This suggests that membrane disruption resulting from direct interaction with PS nanoplastics has little correlation with cytotoxicity. Furthermore, the level of bilayer disruption was found to be limited to the hydrophilic headgroup, indicating that transmembrane diffusion was an unlikely pathway for cellular uptake-endocytosis is the viable mechanism. In rare cases, small PS nanoplastics (20 nm) were found in the vicinity of chromosomes without a nuclear membrane surrounding them; however, this was not observed for larger PS nanoplastics (200 nm). We hypothesize that the nanoplastics can interact with chromosomes prior to nuclear membrane formation. Overall, precoating PS particles with protein coronae reduced the cytotoxicity, irrespective of the corona type. When comparing the two types, the extent of reduction was more apparent with soft than hard corona.

Effects of Protein Source on Liposome Uptake by Cells: Corona Composition and Impact of the Excess Free Proteins

Corona formation in biological fluids strongly affects nanomedicine interactions with cells. However, relatively less is known on additional effects from the free proteins in solution. Within this context, this study aims to gain a better understanding of nanomaterial-cell interactions in different biological fluids and, more specifically, to disentangle effects due to corona composition and those from the free proteins in solution. To this aim, the uptake of liposomes in medium with bovine and human serum are compared. Uptake efficiency in the two media differs strongly, as also corona composition. However, in contrast with similar studies on other nanomaterials, despite the very different corona, when the two corona-coated liposomes are exposed to cells in serum free medium, their uptake is comparable. Thus, in this case, the observed differences in uptake depend primarily on the presence and source of the free proteins. Similar results are obtained when testing the liposomes on different human cells, as well as in murine cells and in the presence of murine serum. Overall, these results show that the protein source affects nanomedicine uptake not only due to effects on corona composition, but also due to the presence and composition of the free proteins in solution.

Effect of Protein Corona on Mitochondrial Targeting Ability and Cytotoxicity of Triphenylphosphonium Conjugated with Polyglycerol-Functionalized Nanodiamond

Functionalization of nanoparticles (NPs) with targeting moieties has a high potential to advance precision nanomedicine. However, the targeting moieties on a NP surface are known to be masked by a protein corona in biofluids, lowering the targeting efficiency. Although it has been demonstrated at the cellular level, little is known about the influence of the protein corona on the subcellular targeting. Herein, we adopted triphenylphosphonium (TPP) as a mitochondrial targeting moiety and investigated the effects of protein coronas from fetal bovine serum and human plasma on its targeting ability and cytotoxicity. Specifically, we introduced TPP in low (l) and high (h) densities on the surface of nanodiamond (ND) functionalized with polyglycerol (PG). Despite the "corona-free" PG interface, we found that the TPP moiety attracted proteins to form a corona layer with clear linearity between the TPP density and the protein amount. By performing investigations on human cervix epithelium (HeLa) and human lung epithelial carcinoma (A549) cells, we further demonstrated that (1) the protein corona alleviated the cytotoxicity of both ND-PG-TPP-l and -h, (2) a smaller amount of proteins on the surface of ND-PG-TPP-l did not affect its mitochondrial targeting ability, and (3) a larger amount of proteins on the surface of ND-PG-TPP-h diminished its targeting specificity by restricting the NDs inside the endosome and lysosome compartments. Our findings will provide in-depth insights into the design of NPs with active targeting moiety for more precise and safer delivery at the subcellular level.

Artificial Protein Coronas Enable Controlled Interaction with Corneal Epithelial Cells: New Opportunities for Ocular Drug Delivery

Topical administration is the most convenient route for ocular drug delivery, but only a minor fraction is retained in the precorneal pocket. To overcome this limitation, numerous drug delivery systems (DDS) have been developed. The protein corona (PC) is the layer of biomolecules (e.g., proteins, sugars, lipids, etc.) that forms around DDS in physiological environments by non-covalent interaction. The PC changes the DDS physical-chemical properties, providing them with a completely novel biological identity. The specific involvement of PC in ocular drug delivery has not been addressed so far. To fulfill this gap, here we explored the interaction between a library of four cationic liposome-DNA complexes (lipoplexes) and mucin (MUC), one of the main components of the tear film. We demonstrate that MUC binds to the lipoplex surface shifting both their size and surface charge and reducing their absorption by primary corneal epithelial cells. To surpass such restrictions, we coated lipoplexes with two different artificial PCs made of Fibronectin (FBN) and Val-Gly-Asp (VGA) tripeptide that are recognized by receptors expressed on the ocular surface. Both these functionalizations remarkedly boosted internalization in corneal epithelial cells with respect to pristine (i.e., uncoated) lipoplexes. This opens the gateway for the exploitation of artificial protein corona in targeted ocular delivery, which will significantly influence the development of novel nanomaterials.

Inorganic material based macrophage regulation for cancer therapy: basic concepts and recent advances

Macrophages with the M1 phenotype are a type of immune cell with exciting prospects for cancer therapy; however, when these macrophages infiltrate into tumours, many of them are induced by the tumour microenvironment to transform into the M2 type, which can enable tumour defence against external therapeutic strategies, assisting in tumour development. Macrophages have strong plasticity and functional heterogeneity, and their phenotypic transformation is complex and still poorly understood in relation to cancer therapy. Recent material advances in inorganic nanomaterials, especially inorganic elements in vivo, have accelerated the development of macrophage regulation-based cancer treatments. This review summarizes the basics of recent research on macrophage phenotype transformation and discusses the current challenges in macrophage type regulation. Then, the current achievements involving inorganic material-based macrophage regulation and the related anticancer effects of induced macrophages and their extracellular secretions are reviewed systematically. Importantly, inorganic nanomaterial-based macrophage phenotype regulation is flexible and can be adapted for different types of cancer therapies, presenting a possible novel approach for the generation of immune materials for cancer therapy.

Protein nanoparticles in drug delivery: animal protein, plant proteins and protein cages, albumin nanoparticles

In this article, we will describe the properties of albumin and its biological functions, types of sources that can be used to produce albumin nanoparticles, methods of producing albumin nanoparticles, its therapeutic applications and the importance of albumin nanoparticles in the production of pharmaceutical formulations. In view of the increasing use of Abraxane and its approval for use in the treatment of several types of cancer and during the final stages of clinical trials for other cancers, to evaluate it and compare its effectiveness with conventional non formulations of chemotherapy Paclitaxel is paid. In this article, we will examine the role and importance of animal proteins in Nano medicine and the various benefits of these biomolecules for the preparation of drug delivery carriers and the characteristics of plant protein Nano carriers and protein Nano cages and their potentials in diagnosis and treatment. Finally, the advantages and disadvantages of protein nanoparticles are mentioned, as well as the methods of production of albumin nanoparticles, its therapeutic applications and the importance of albumin nanoparticles in the production of pharmaceutical formulations.

Binding-Mediated Formation of Ribonucleoprotein Corona for Efficient Delivery and Control of CRISPR/Cas9

Protein coronae formed with nanoparticles confer several useful properties. However, the non-specific nature of protein corona formation makes it difficult to deliver specific proteins for therapeutic applications. Herein, we report on the construction of a new type of protein corona, termed binding-mediated protein corona. This new corona enables the efficient and controllable delivery of functional proteins, which is otherwise challenging for conventional protein coronae. We show the design and delivery of the ribonucleoprotein corona for the CRISPR/Cas9 system. Successful gene editing in human cell lines (Hela and HEK293) demonstrates the efficient delivery, high stability, low cytotoxicity, and well-controlled activity of the Cas9-guide RNA ribonucleoprotein. The binding-mediated protein corona strategy opens up new opportunities for therapeutic protein delivery.

Understanding nanoparticle endocytosis to improve targeting strategies in nanomedicine

Nanoparticles (NPs) have attracted considerable attention in various fields, such as cosmetics, the food industry, material design, and nanomedicine. In particular, the fast-moving field of nanomedicine takes advantage of features of NPs for the detection and treatment of different types of cancer, fibrosis, inflammation, arthritis as well as neurodegenerative and gastrointestinal diseases. To this end, a detailed understanding of the NP uptake mechanisms by cells and intracellular localization is essential for safe and efficient therapeutic applications. In the first part of this review, we describe the several endocytic pathways involved in the internalization of NPs and we discuss the impact of the physicochemical properties of NPs on this process. In addition, the potential challenges of using various inhibitors, endocytic markers and genetic approaches to study endocytosis are addressed along with the principal (semi) quantification methods of NP uptake. The second part focuses on synthetic and bio-inspired substances, which can stimulate or decrease the cellular uptake of NPs. This approach could be interesting in nanomedicine where a high accumulation of drugs in the target cells is desirable and clearance by immune cells is to be avoided. This review contributes to an improved understanding of NP endocytic pathways and reveals potential substances, which can be used in nanomedicine to improve NP delivery.

Impact of bovine serum albumin - A protein corona on toxicity of ZnO NPs in environmental model systems of plant, bacteria, algae and crustaceans

Zinc oxide nanoparticles (ZnO NPs) are widely applied in industrial, household and medical areas that lead to its discharge and accumulation in ecosystem. Here, the toxic effect of ZnO NPs in presence and absence of bovine serum albumin (BSA) was analyzed. The difference in toxicity of bare ZnO and BSA interacted ZnO was studied with different environmental models. P. aeruginosa and S. aureus were used as model bacterial systems. Toxicity against bacteria was determined by employing plate count method. C. pyrenoidsa was used as algal system for evaluating toxicity and it was determined by chlorophyll estimation assay. Daphnia sp. was chosen as crustacean system model. A. cepa root cells were chosen as plant model. ZnO NPs increased the ROS formation, lipid peroxidation and oxidative stress and it reduced in the presence of BSA. The cytotoxicity, chromosomal aberrations and micronuclei (MN) index of A. cepa were increased after ZnO NPs treatment. Same time the toxic effect was decreased in case of BSA coated ZnO NPs. The NPs toxic potential on the organisms decreased in the order of P. aeruginosa (LC₅₀-0.092 mg/L) > S. aureus (LC₅₀-0.33 mg/L) > Daphnia sp (LC₅₀-0.35 mg/L) > C. pyrenoidosa (LC₅₀-8.17 mg/L). LC₅₀ in presence of BSA was determined to be 18.45, 26.24, 17.27 and 53.97 mg/L for P. aeruginosa, S. aureus, Daphnia sp and C. pyrenoidosa respectively. Therefore, the report suggests that BSA stabilized ZnO NPs could be more amenable towards applications in biotechnology and bioengineering.

Protein-nanoparticle interactions and a new insight

The study of protein-nanoparticle interactions provides knowledge about the bio-reactivity of nanoparticles, and creates a database of nanoparticles for applications in nanomedicine, nanodiagnosis, and nanotherapy. The problem arises when nanoparticles come in contact with physiological fluids such as plasma or serum, wherein they interact with the proteins (or other biomolecules). This interaction leads to the coating of proteins on the nanoparticle surface, mostly due to the electrostatic interaction, called 'corona'. These proteins are usually partially unfolded. The protein corona can deter nanoparticles from their targeted functionalities, such as drug/DNA delivery at the site and fluorescence tagging of diseased tissues. The protein corona also has many repercussions on cellular intake, inflammation, accumulation, degradation, and clearance of the nanoparticles from the body depending on the exposed part of the proteins. Hence, the protein-nanoparticle interaction and the configuration of the bound-proteins on the nanosurface need thorough investigation and understanding. Several techniques such as DLS and zeta potential measurement, UV-vis spectroscopy, fluorescence spectroscopy, circular dichroism, FTIR, and DSC provide valuable information in the protein-nanoparticle interaction study. Besides, theoretical simulations also provide additional understanding. Despite a lot of research publications, the fundamental question remained unresolved. Can we aim for the application of functional nanoparticles in medicine? A new insight, given by us, in this article assumes a reasonable solution to this crucial question.

Toxic effect and mechanism of ultrafine carbon black on mouse primary splenocytes and two digestive enzymes

This paper investigated the toxic effect and mechanism of ultrafine carbon black (UFCB) on splenocytes and enzymes in the digestive system. It was found that the toxicity of UFCB to splenocytes was dose-dependent. UFCB with a low concentration (<15 μg/mL) had no significant effect on splenocytes while UFCB with high concentration (>15 μg/mL) induced significant oxidative damage with increased content of reactive oxygen species (ROS) (134%) and malonaldehyde (MDA) (222.3%) along with the decreased activity of superoxide dismutase (SOD) (55.63%) and catalase (CAT) (87.73%). Analysis combined cellular and molecular levels indicated that UFCB induced splenocyte toxicity through oxidative stress. The interactions of UFCB with two important digestive enzymes, α-amylase and lipase, were also studied respectively. Results showed that the interaction of UFCB and the two enzymes altered the particle size and fluorescence intensity in both experimental systems. The formation of protein corona also resulted in the contraction of the polypeptide skeleton in both enzymes, which further inhibited their activity. Our work provided basic data on the toxicity of UFCB in the spleen and digestive system and fills the gap in the study of UFPs toxicity. CAPSULE: UFCB induced splenocyte toxicity and enzyme dysfunction through oxidative stress and protein corona formation respectively.

Unfolded Protein Corona Surrounding Nanotubes Influence the Innate and Adaptive Immune System

The plasma proteins around nanoparticles (NPs) form an outer protein corona, significantly influencing the subsequent immune response. However, it was uncertain whether the protein corona around NPs influences immune response. This study clarified that the immune response mediated by the protein corona is greatly dependent on the type of plasma proteins surrounding the NPs. Structural changes in the unfolded protein corona elevated reactive oxygen species (ROS) levels and induced major proinflammatory cytokine release in both murine and human macrophage cell lines. In contrast, negligible structural changes in the protein corona provoke neither ROS production nor proinflammatory cytokine release. Furthermore, in vivo analysis confirms that a stimulated immune response by an unfolded protein corona triggers selective activation of innate and adaptive immunity in the spleen. Specifically, neutrophils, natural killer cells, and CD8+ T cells are overpopulated by unfolded protein corona structures surrounding nanotubes, whereas innate and adaptive immunologic responses are not triggered by a normal protein corona. In conclusion, highly unfolded protein corona structures are strongly correlated with subsequent activation of proinflammatory cytokines and innate immune responses; thus, the protein corona can be used in immune-enhancing therapy.

Hard and Soft Protein Corona of Nanomaterials: Analysis and Relevance

Upon contact with a biological milieu, nanomaterials tend to interact with biomolecules present in the media, especially proteins, leading to the formation of the so-called "protein corona". As a result of these nanomaterial-protein interactions, the bio-identity of the nanomaterial is altered, which is translated into modifications of its behavior, fate, and pharmacological profile. For biomedical applications, it is fundamental to understand the biological behavior of nanomaterials prior to any clinical translation. For these reasons, during the last decade, numerous publications have been focused on the investigation of the protein corona of many different types of nanomaterials. Interestingly, it has been demonstrated that the structure of the protein corona can be divided into hard and soft corona, depending on the affinity of the proteins for the nanoparticle surface. In the present document, we explore the differences between these two protein coronas, review the analysis techniques used for their assessment, and reflect on their relevance for medical purposes.