Protein corona mitigates the cytotoxicity of graphene oxide by reducing its physical interaction with cell membrane

Understanding interactions between biomolecules and two-dimensional nanomaterials using in silico microscopes

Two-dimensional (2D) nanomaterials such as graphene are increasingly used in research and industry for various biomedical applications. Extensive experimental and theoretical studies have revealed that 2D nanomaterials are promising drug delivery vehicles, yet certain materials exhibit toxicity under biological conditions. So far, it is known that 2D nanomaterials possess strong adsorption propensities for biomolecules. To mitigate potential toxicity and retain favorable physical and chemical properties of 2D nanomaterials, it is necessary to explore the underlying mechanisms of interactions between biomolecules and nanomaterials for the subsequent design of biocompatible 2D nanomaterials for nanomedicine. The purpose of this review is to integrate experimental findings with theoretical observations and facilitate the study of 2D nanomaterial interaction with biomolecules at the molecular level. We discuss the current understanding and progress of 2D nanomaterial interaction with proteins, lipid membranes, and DNA based on molecular dynamics (MD) simulation. In this review, we focus on the 2D graphene nanosheet and briefly discuss other 2D nanomaterials. With the ever-growing computing power, we can image nanoscale processes using MD simulation that are otherwise not observable in experiment. We expect that molecular characterization of the complex behavior between 2D nanomaterials and biomolecules will help fulfill the goal of designing effective 2D nanomaterials as drug delivery platforms.

Impact of surface chemistry of ultrasmall superparamagnetic iron oxide nanoparticles on protein corona formation and endothelial cell uptake, toxicity, and barrier function

Ultrasmall superparamagnetic iron oxide nanoparticles (USPION) have been investigated for biomedical applications, including novel contrast agents, magnetic tracers for tumor imaging, targeted drug delivery vehicles, and magneto-mechanical actuators for hyperthermia and thrombolysis. Despite significant progress, recent clinical reports have raised concerns regarding USPION safety related to endothelial cell dysfunction; however, there is limited information on factors contributing to these clinical responses. The influence of USPION surface chemistry on nanoparticle interactions with proteins may impact endothelial cell function leading to adverse responses. Therefore, the goal of this study was to assess the effects of carboxyl-functionalized USPION (CU) or amine-functionalized USPION (AU) (∼30 nm diameter) on biological responses in human coronary artery endothelial cells. Increased protein adsorption was observed for AU compared to CU after exposure to serum proteins. Exposure to CU, but not AU, resulted in a concentration-dependent decrease in cell viability and perinuclear accumulation inside cytoplasmic vesicles. Internalization of CU was correlated with endothelial cell functional changes under non-cytotoxic conditions, as evidenced by a marked decreased expression of endothelial-specific adhesion proteins (e.g., VE-cadherin and PECAM-1) and increased endothelial permeability. Evaluation of downstream signaling indicated endothelial permeability is associated with actin cytoskeleton remodeling, possibly elicited by intracellular events involving reactive oxygen species, calcium ions, and the nanoparticle cellular uptake pathway. This study demonstrated that USPION surface chemistry significantly impacts protein adsorption and endothelial cell uptake, viability, and barrier function. This information will advance the current toxicological profile of USPION and improve development, safety assessment, and clinical outcomes of USPION-enabled medical products.

Biological interactions of ferromagnetic iron oxide-carbon nanohybrids with alveolar epithelial cells

Iron oxide nanoparticles (IONPs) have been largely investigated in a plethora of biological fields for their interesting physical-chemical properties, which make them suitable for application in cancer therapy, neuroscience, and imaging. Several encouraging results have been reported in these contexts. However, the possible toxic effects of some IONP formulations can limit their applicability. In this work, IONPs were synthesized with a carbon shell (IONP@C), providing enhanced stability both as colloidal dispersion and in the biological environment. We conducted a careful multiparametric evaluation of IONP@C biological interactions in vitro, providing them with an in vivo-like biological identity. Our hybrid nanoformulation showed no cytotoxic effects on a widely employed model of alveolar epithelial cells for a variety of concentrations and exposure times. The IONP@C were efficiently internalized and TEM analysis allowed the protective role of the carbon shell against intracellular degradation to be assessed. Intracellular redistribution of the IONP@C from the lysosomes to the lamellar bodies was also observed after 72 hours.

The Construction of a Self-assembled Coating with Chitosan-Grafted Reduced Graphene Oxide on Porous Calcium Polyphosphate Scaffolds for Bone Tissue Engineering

Bone regeneration in large bone defects remains one of the major challenges in orthopedic surgery. Calcium polyphosphate (CPP) scaffolds possess excellent biocompatibility and exhibits good bone ingrowth. However, the present CPP scaffolds lack enough osteoinductive activity to facilitate bone regeneration at bone defects that exceed the critical size threshold. To endow CPP scaffolds with improved osteoinductive activity for better bone regeneration, in this study, a self-assembled coating with chitosan-grafted reduced graphene oxide (CS-rGO) sheets was successfully constructed onto the surface of CPP scaffolds through strong electrostatic interaction and hydrogen bonds. Our results showed that the obtained CPP/CS-rGO composite scaffolds exhibited highly improved biomineralization and considerable antibacterial activity. More importantly, CPP/CS-rGO composite scaffolds could drive osteogenic differentiation of BMSCs and significantly up-regulate the expression of osteogenesis-related proteins in vitro. Meanwhile, the CS-rGO coating could inhibit aseptic loosening and improve interfacial osseointegration through stimulating BMSCs to secrete more OPG and lesser RANKL. Overall, the CS-rGO coating adjusts CPP scaffolds' biological environment interface and endows CPP scaffolds with more bioactivity.

Controllable Environment Protein Corona-Disguised Immunomagnetic Beads for High-Performance Circulating Tumor Cell Enrichment

The enrichment performance of immunomagnetic beads (IMBs) in blood samples is usually challenging due to the ungoverned, in situ-formed protein corona, as it generally leads to negative effects, such as impeded targeting capacity and unwanted nonspecific absorption. On the contrary, a controlled protein premodification of IMBs with diverse functional environment (blood) proteins endows the composites with a new biological identity and may improve the anti-nonspecific ability, resulting in promising isolation benefits for circulating tumor cell (CTC) enrichment and downstream analyses. Specifically, fetal bovine serum and the four most abundant blood proteins, including human serum albumin, fibrinogen, immunoglobulin, and transferrin, were separately applied in this work. Conclusively, the biological properties of the applied protein corona camouflage have a great influence on the capture performance of IMBs, and certain proteins can enhance the enrichment performance to a large extent. Promisingly, human serum albumin-camouflaged IMBs (HSA-PIMBs) achieved a capture efficiency of 84.0-90.0% and significantly minimized nonspecific absorbed leukocytes to 164-264 in blood samples (0.5 mL, 25-55 model CTCs). Furthermore, HSA-PIMBs isolated 62-505 CTCs and 13-31 leukocytes from the blood samples of five cancer patients. The novel environment camouflage strategy provides a new insight into protein corona utilization and may improve the performance of targeted nanomaterials in a complex biological environment.

Graphene oxide toxicity in W1118 flies

The risk of graphene oxide (GO) exposure to various species has been greatly amplified in recent years due to its booming production and applications in various fields. However, a deep understanding of the GO biosafety lags its wide applications. Herein, we used W¹¹¹⁸ flies as a model organism to study GO toxicity at relatively low concentrations. We found that GO exposure led to remarkable weight loss, delayed development, retarded motion, and shortened lifespan of these flies. On the other hand, the GO influence on their sex ratio and the total number of pupae and adults were insignificant. The toxicological effect of GO was shown to be related to its serious compromise of the nutrient absorption in flies due to the severe damages in midguts. These damages were then attributed to the excessive accumulation of reactive oxygen species (ROS), which triggers the oxidative stress. These findings reveal the underlying mechanisms of GO biotoxicities in fruit flies, which might provide a useful reference to assess the risks of these newly invented nanomaterials likely never encountered by various species before.

Artificial cell membrane camouflaged immunomagnetic nanoparticles for enhanced circulating tumor cells isolation

Precise and specific circulating tumor cells (CTCs) isolation is heavily interfered by blood cells and proteins. Though satisfactory results have been achieved by some cell membrane-derived platforms, following limitations have...

Interaction of Graphene Oxide Modified with Linear and Branched PEG with Monocytes Isolated from Human Blood

Multiple graphene-based therapeutics have recently been developed, however potential risks related to the interaction between nanomaterials and immune cells are still poorly understood. Therefore, studying the impact of graphene oxide on various populations of immune cells is of importance. In this work, we aimed to investigate the effects of PEGylated graphene oxide on monocytes isolated from human peripheral blood. Graphene oxide nanoparticles with lateral sizes of 100–200 nm and 1–5 μm were modified with linear and branched PEG (GO-PEG). Size, elemental composition, and structure of the resulting nanoparticles were characterized. We confirmed that PEG was successfully attached to the graphene oxide surface. The influence of GO-PEG on the production of reactive oxygen species (ROS), cytokines, phagocytosis, and viability of monocytes was studied. Uptake of GO-PEG by monocytes depends on PEG structure (linear or branched). Branched PEG decreased the number of GO-PEG nanoparticles per monocyte. The viability of monocytes was not altered by co-cultivation with GO-PEG. GO-PEG decreased the phagocytosis of Escherichia coli in a concentration-dependent manner. ROS formation by monocytes was determined by measuring luminol-, lucigenin-, and dichlorodihydrofluorescein-dependent luminescence. GO-PEG decreased luminescent signal probably due to inactivation of ROS, such as hydroxyl and superoxide radicals. Some types of GO-PEG stimulated secretion of IL-10 by monocytes, but this effect did not correlate with their size or PEG structure.

Potential interference of graphene nanosheets in immune response via disrupting the recognition of HLA-presented KK10 by TCR: a molecular dynamics simulation study

Graphene and its derivatives have emerged as a promising nanomaterial in biomedical applications. However, their impact on biosafety continues to be a concern in the field, particularly, their potential cytotoxicity to our immune system. In this study, we used all-atom molecular dynamics simulations to investigate the potential interference of graphene nanosheets in antigen presentation and recognition in immune response. For the illustrated human immunodeficiency virus (HIV) antigen peptide KK10, human leukocyte antigen (HLA), and T cell receptor (TCR) ternary complex, we found that the graphene nanosheet could disrupt the critical protein-protein interactions between TCR and peptide-HLA and impair the antigen recognition by TCR, leaving the antigen presentation unaffected. Moreover, the hydrophobic interaction and van der Waals potential energy collectively drive the spontaneous separation of TCR from the peptide-HLA complex by graphene nanosheets. Our findings demonstrated theoretically how the graphene nanosheet could interfere with the immune response and provided useful insights for reducing the risk of graphene-based nanomaterials in biomedical applications.

Promising Graphene-Based Nanomaterials and Their Biomedical Applications and Potential Risks: A Comprehensive Review

Graphene-based nanomaterials (GBNs) have been the subject of research focus in the scientific community because of their excellent physical, chemical, electrical, mechanical, thermal, and optical properties. Several studies have been conducted on GBNs, and they have provided a detailed review and summary of various applications. However, comprehensive comments on biomedical applications and potential risks and strategies to reduce toxicity are limited. In this review, we systematically summarized the following aspects of GBNs in order to fill the gaps: (1) the history, synthesis methods, structural characteristics, and surface modification; (2) the latest advances in biomedical applications (including drug/gene delivery, biosensors, bioimaging, tissue engineering, phototherapy, and antibacterial activity); and (3) biocompatibility, potential risks (toxicity in vivo/vitro and effects on human health and the environment), and strategies to reduce toxicity. Moreover, we have analyzed the challenges to be overcome in order to enhance application of GBNs in the biomedical field.

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.

Sulfur vacancies affect the environmental fate, corona formation, and microalgae toxicity of molybdenum disulfide nanoflakes

Sulfur vacancy (SV) defects have been engineered in two-dimensional (2D) transition metal dichalcogenides (TMDs) for high performance applications in various fields involving environmental protection. Understanding the influence of SVs on the environmental fate and toxicity of TMDs is critical for evaluating their risk. Our work discovered that SVs (with S/Mo ratios of 1.65 and 1.32) reduced the dispersibility and promoted aggregation of 2H phase molybdenum disulfide (2H-MoS₂, a hot TMD) in aqueous solution. The generation capability of •O₂^- and •OH was increased and the dissolution of 2H-MoS₂ was significantly accelerated after SVs formation. Different with pristine form, S-vacant 2H-MoS₂ preferentially harvested proteins (i.e., forming protein corona) involved in antioxidation, photosynthetic electron transport, and the cytoskeleton structure of microalgae. These proteins contain a higher relative number of thiol groups, which exhibited stronger affinity to S-vacant than pristine 2H-MoS₂, as elucidated by density functional theory calculations. Notably, SVs aggravated algal growth inhibition, oxidative damage, photosynthetic efficiency and cell membrane permeability reduction induced by 2H-MoS₂ due to increased free radical yield and the specific binding of functional proteins. Our findings provide insights into the roles of SVs on the risk of MoS₂ while highlighting the importance of rational design for TMDs application.

Polyelectrolyte Encapsulation and Confinement within Protein Cage-Inspired Nanocompartments

Protein cages are nanocompartments with a well-defined structure and monodisperse size. They are composed of several individual subunits and can be categorized as viral and non-viral protein cages. Native viral cages often exhibit a cationic interior, which binds the anionic nucleic acid genome through electrostatic interactions leading to efficient encapsulation. Non-viral cages can carry various cargo, ranging from small molecules to inorganic nanoparticles. Both cage types can be functionalized at targeted locations through genetic engineering or chemical modification to entrap materials through interactions that are inaccessible to wild-type cages. Moreover, the limited number of constitutional subunits ease the modification efforts, because a single modification on the subunit can lead to multiple functional sites on the cage surface. Increasing efforts have also been dedicated to the assembly of protein cage-mimicking structures or templated protein coatings. This review focuses on native and modified protein cages that have been used to encapsulate and package polyelectrolyte cargos and on the electrostatic interactions that are the driving force for the assembly of such structures. Selective encapsulation can protect the payload from the surroundings, shield the potential toxicity or even enhance the intended performance of the payload, which is appealing in drug or gene delivery and imaging.

Modulation of Cancer Cell Autophagic Responses by Graphene-Based Nanomaterials: Molecular Mechanisms and Therapeutic Implications

Simple Summary

Graphene-based nanomaterials (GNM) are one-to-several carbon atom-thick flakes of graphite with at least one lateral dimension <100 nm. The unique electronic structure, high surface-to-volume ratio, and relatively low toxicity make GNM potentially useful in cancer treatment. GNM such as graphene, graphene oxide, graphene quantum dots, and graphene nanofibers are able to induce autophagy in cancer cells. During autophagy the cell digests its own components in organelles called lysosomes, which can either kill cancer cells or promote their survival, as well as influence the immune response against the tumor. However, a deeper understanding of GNM-autophagy interaction at the mechanistic and functional level is needed before these findings could be exploited to increase GNM effectiveness as cancer therapeutics and drug delivery systems. In this review, we analyze molecular mechanisms of GNM-mediated autophagy modulation and its possible implications for the use of GNM in cancer therapy.

Abstract

Graphene-based nanomaterials (GNM) are plausible candidates for cancer therapeutics and drug delivery systems. Pure graphene and graphene oxide nanoparticles, as well as graphene quantum dots and graphene nanofibers, were all able to trigger autophagy in cancer cells through both transcriptional and post-transcriptional mechanisms involving oxidative/endoplasmic reticulum stress, AMP-activated protein kinase, mechanistic target of rapamycin, mitogen-activated protein kinase, and Toll-like receptor signaling. This was often coupled with lysosomal dysfunction and subsequent blockade of autophagic flux, which additionally increased the accumulation of autophagy mediators that participated in apoptotic, necrotic, or necroptotic death of cancer cells and influenced the immune response against the tumor. In this review, we analyze molecular mechanisms and structure–activity relationships of GNM-mediated autophagy modulation, its consequences for cancer cell survival/death and anti-tumor immune response, and the possible implications for the use of GNM in cancer therapy.

Understanding the interactions between inorganic-based nanomaterials and biological membranes

The interactions between inorganic-based nanomaterials (NMs) and biological membranes are among the most important phenomena for developing NM-based therapeutics and resolving nanotoxicology. Herein, we introduce the structural and functional effects of inorganic-based NMs on biological membranes, mainly the plasma membrane and the endomembrane system, with an emphasis on the interface, which involves highly complex networks between NMs and biomolecules (such as membrane proteins and lipids). Significant efforts have been devoted to categorizing and analyzing the interaction mechanisms in terms of the physicochemical characteristics and biological effects of NMs, which can directly or indirectly influence the effects of NMs on membranes. Importantly, we summarize that the biological membranes act as platforms and thereby mediate NMs-immune system contacts. In this overview, the existing challenges and potential applications in the areas are addressed. A strong understanding of the discussed concepts will promote therapeutic NM designs for drug delivery systems by leveraging the NMs-membrane interactions and their functions.

Surface Functionalization of Graphene-Based Materials: Biological Behavior, Toxicology, and Safe-By-Design Aspects

The increasing exploitation of graphene-based materials (GBMs) is driven by their unique properties and structures, which ignite the imagination of scientists and engineers. At the same time, the very properties that make them so useful for applications lead to growing concerns regarding their potential impacts on human health and the environment. Since GBMs are inert to reaction, various attempts of surface functionalization are made to make them reactive. Herein, surface functionalization of GBMs, including those intentionally designed for specific applications, as well as those unintentionally acquired (e.g., protein corona formation) from the environment and biota, are reviewed through the lenses of nanotoxicity and design of safe materials (safe-by-design). Uptake and toxicity of functionalized GBMs and the underlying mechanisms are discussed and linked with the surface functionalization. Computational tools that can predict the interaction of GBMs behavior with their toxicity are discussed. A concise framing of current knowledge and key features of GBMs to be controlled for safe and sustainable applications are provided for the community.

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.

Antipathogenic properties and applications of low-dimensional materials

A major health concern of the 21st century is the rise of multi-drug resistant pathogenic microbial species. Recent technological advancements have led to considerable opportunities for low-dimensional materials (LDMs) as potential next-generation antimicrobials. LDMs have demonstrated antimicrobial behaviour towards a variety of pathogenic bacterial and fungal cells, due to their unique physicochemical properties. This review provides a critical assessment of current LDMs that have exhibited antimicrobial behaviour and their mechanism of action. Future design considerations and constraints in deploying LDMs for antimicrobial applications are discussed. It is envisioned that this review will guide future design parameters for LDM-based antimicrobial applications.

Application of nanoparticles in bone tissue engineering; a review on the molecular mechanisms driving osteogenesis

The introduction of nanoparticles into bone tissue engineering strategies is beneficial to govern cell fate into osteogenesis and the regeneration of large bone defects. The present study explored the role of nanoparticles to advance osteogenesis with a focus on the cellular and molecular pathways involved. Pubmed, Pubmed Central, Embase, Scopus, and Science Direct databases were explored for those published articles relevant to the involvement of nanoparticles in osteogenic cellular pathways. As multifunctional compounds, nanoparticles contribute to scaffold-free and scaffold-based tissue engineering strategies to progress osteogenesis and bone regeneration. They regulate inflammatory responses and osteo/angio/osteoclastic signaling pathways to generate an osteogenic niche. Besides, nanoparticles interact with biomolecules, enhance their half-life and bioavailability. Nanoparticles are promising candidates to promote osteogenesis. However, the interaction of nanoparticles with the biological milieu is somewhat complicated, and more considerations are recommended on the employment of nanoparticles in clinical applications because of NP-induced toxicities.

Graphene Family Nanomaterials in Ocular Applications: Physicochemical Properties and Toxicity

Graphene family nanomaterials (GFNs) are rapidly emerging for ocular applications due to their outstanding physicochemical properties. Since the eyes are very sensitive organs and the contact between the eyes and GFNs in eye drops, contact lenses, intraocular drug delivery systems and biosensors and even the workers handling these nanomaterials is inevitable, it is necessary to investigate their ocular toxicities and physiological interactions with cells as well as their toxicity mechanisms. The toxicity of GFNs can be extremely affected by their physicochemical properties, including composition, size, surface chemistry, and oxidation level as well as dose and the time of exposure. Up to now, there are several studies on the in vitro and in vivo toxicity of GFNs; however, a comprehensive review on ocular toxicity and applications of GFNs is missing, and a knowledge about the health risks of eye exposure to the GFNs is predominantly unspecified. This review highlights the ocular applications of GFNs and systematically covers the most recent advances of GFNs' physicochemical properties, in vitro and in vivo ocular toxicity, and the possible toxicity mechanisms as well as provides some perspectives on the potential risks of GFNs in material development and biomedical applications.

Carbon-Based Nanomaterials: Promising Antiviral Agents to Combat COVID-19 in the Microbial-Resistant Era

Therapeutic options for the highly pathogenic human severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing the current pandemic coronavirus disease (COVID-19) are urgently needed. COVID-19 is associated with viral pneumonia and acute respiratory distress syndrome causing significant morbidity and mortality. The proposed treatments for COVID-19 have shown little or no effect in the clinic so far. Additionally, bacterial and fungal pathogens contribute to the SARS-CoV-2-mediated pneumonia disease complex. The antibiotic resistance in pneumonia treatment is increasing at an alarming rate. Therefore, carbon-based nanomaterials (CBNs), such as fullerene, carbon dots, graphene, and their derivatives constitute a promising alternative due to their wide-spectrum antimicrobial activity, biocompatibility, biodegradability, and capacity to induce tissue regeneration. Furthermore, the antimicrobial mode of action is mainly physical (e.g., membrane distortion), characterized by a low risk of antimicrobial resistance. In this Review, we evaluated the literature on the antiviral activity and broad-spectrum antimicrobial properties of CBNs. CBNs had antiviral activity against 13 enveloped positive-sense single-stranded RNA viruses, including SARS-CoV-2. CBNs with low or no toxicity to humans are promising therapeutics against the COVID-19 pneumonia complex with other viruses, bacteria, and fungi, including those that are multidrug-resistant.

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.

Molecular Modeling of Protein Corona Formation and Its Interactions with Nanoparticles and Cell Membranes for Nanomedicine Applications

The conformations and surface properties of nanoparticles have been modified to improve the efficiency of drug delivery. However, when nanoparticles flow through the bloodstream, they interact with various plasma proteins, leading to the formation of protein layers on the nanoparticle surface, called protein corona. Experiments have shown that protein corona modulates nanoparticle size, shape, and surface properties and, thus, influence the aggregation of nanoparticles and their interactions with cell membranes, which can increases or decreases the delivery efficiency. To complement these experimental findings and understand atomic-level phenomena that cannot be captured by experiments, molecular dynamics (MD) simulations have been performed for the past decade. Here, we aim to review the critical role of MD simulations to understand (1) the conformation, binding site, and strength of plasma proteins that are adsorbed onto nanoparticle surfaces, (2) the competitive adsorption and desorption of plasma proteins on nanoparticle surfaces, and (3) the interactions between protein-coated nanoparticles and cell membranes. MD simulations have successfully predicted the competitive binding and conformation of protein corona and its effect on the nanoparticle-nanoparticle and nanoparticle-membrane interactions. In particular, simulations have uncovered the mechanism regarding the competitive adsorption and desorption of plasma proteins, which helps to explain the Vroman effect. Overall, these findings indicate that simulations can now provide predications in excellent agreement with experimental observations as well as atomic-scale insights into protein corona formation and interactions.

Stealthiness and Hematocompatibility of Gold Nanoparticles with Pre-Formed Protein Corona

Studies have established that a serum protein corona pre-formed around gold nanorods (NRs) could be exploited for loading photosensitizers and chemotherapeutics to result in efficient cell kill in vitro with an extremely low dose. In this study, we further demonstrated that pre-forming a serum protein corona (PC) around citrate-capped NRs (NR-Cit) to form NR-PC conferred them stealth property and high hematocompatibility similar to the common strategy of PEGylating NRs, which would otherwise not be able to evade the immune system. Specifically, the NR-PC caused minimal complement activation with significantly lower formation of the terminal complement complex SC5b-9 measured in human serum containing NR-PC, and this resulted in low uptake by phagocytic U937 monocytes of 5.9% of the initial gold dose compared to 55.8% of NR-Cit. In addition, NR-PC exhibited very low hemolytic activity of less than 0.2% hemolysis with no observable effect on RBC morphology as opposed to 0.6% for NR-Cit at the same concentration of 1 nM NRs. Furthermore, we showed that the high hematocompatibility and stealth property of NR-PC were maintained even after the loading of small molecules, photosensitizer Chlorine e6 (Ce6), into the protein corona, thus further establishing the potential clinical relevance of exploiting the inevitably formed serum protein corona on nanoparticles as an effective delivery vector for small molecular therapeutics.

Lateral size of graphene oxide determines differential cellular uptake and cell death pathways in Kupffer cells, LSECs, and hepatocytes

As a representative two-dimensional (2D) nanomaterial, graphene oxide (GO) has shown high potential in many applications due to its large surface area, high flexibility, and excellent dispersibility in aqueous solutions. These properties make GO an ideal candidate for bio-imaging, drug delivery, and cancer therapy. When delivered to the body, GO has been shown to accumulate in the liver, the primary accumulation site of systemic delivery or secondary spread from other uptake sites, and induce liver toxicity. However, the contribution of the GO physicochemical properties and individual liver cell types to this toxicity is unclear due to property variations and diverse cell types in the liver. Herein, we compare the effects of GOs with small (GO-S) and large (GO-L) lateral sizes in three major cell types in liver, Kupffer cells (KCs), liver sinusoidal endothelial cells (LSECs), and hepatocytes. While GOs induced cytotoxicity in KCs, they induced significantly less toxicity in LSECs and hepatocytes. For KCs, we found that GOs were phagocytosed that triggered NADPH oxidase mediated plasma membrane lipid peroxidation, which leads to PLC activation, calcium flux, mitochondrial ROS generation, and NLRP3 inflammasome activation. The subsequent caspase-1 activation induced IL-1β production and GSDMD-mediated pyroptosis. These effects were lateral size-dependent with GO-L showing stronger effects than GO-S. Amongst the liver cell types, decreased cell association and the absence of lipid peroxidation resulted in low cytotoxicity in LSECs and hepatocytes. Using additional GO samples with different lateral sizes, surface functionalities, or thickness, we further confirmed the differential cytotoxic effects in liver cells and the major role of GO lateral size in KUP5 pyroptosis by correlation studies. These findings delineated the GO effects on cellular uptake and cell death pathways in liver cells, and provide valuable information to further evaluate GO effects on the liver for biomedical applications.

The Blanket Effect: How Turning the World Upside Down Reveals the Nature of Graphene Oxide Cytocompatibility

Extensive cytocompatibility testing of 2D nanocarbon materials including graphene oxide (GO) has been performed, but results remain contradictory. Literature has yet to account for settling-although sedimentation is visible to the eye and physics suggests that even individual graphenic flakes will settle. To investigate settling, a series of functional graphenic materials (FGMs) with differing oxidation levels, functionalities, and physical dimensions are synthesized. Though zeta potential indicates colloidal stability, significant gravitational settling of the FGMs is theoretically and experimentally demonstrated. By creating a setup to culture cells in traditional and inverted orientations in the same well, a "blanket effect" is demonstrated in which FGMs settle out of solution and cover cells at the bottom of the well, ultimately reducing viability. Inverted cells protected from the blanket effect are unaffected. Therefore, these results demonstrate that settling is a crucial factor that must be considered for FGM cytocompatibility experiments.

Effect of Protein Corona on Nanoparticle-Lipid Membrane Binding: The Binding Strength and Dynamics

All-atom molecular dynamics simulations of the 10 nm-sized anionic polystyrene (PS) particle complexed with plasma proteins (human serum albumin, immunoglobulin gamma-1 chain-C, and apolipoprotein A-I) adsorbed onto lipid bilayers [asymmetrically composed of extracellular (zwitterionic) and cytosolic (anionic) leaflets] are performed. Free energies calculated from umbrella sampling simulations show that proteins on the particle more weakly bind to the zwitterionic leaflet than do bare particles, in agreement with experiments showing the suppression of the particle-bilayer binding by protein corona. Proteins on the particle interact more strongly with the anionic leaflet than with the zwitterionic leaflet because of charge interactions between cationic protein residues and anionic lipid headgroups, to an extent dependent on various plasma proteins. In particular, hydrogen bonds between proteins and zwitterionic leaflets restrict the motion of lipids and thus reduce the lateral dynamics of bilayers, while the tight binding between proteins and anionic leaflets disrupts the helical structure of proteins and disorders lipids, leading to an increase in the lateral dynamics of bilayers. These findings help explain the experimental observation regarding the fact that the bilayer dynamics decreases when interacting with protein corona and suggest that the effect of protein corona on the binding strength and bilayer dynamics depends on protein types and bilayer charges.

Protein immobilization on graphene oxide or reduced graphene oxide surface and their applications: Influence over activity, structural and thermal stability of protein

Due to the essential role of biological macromolecules in our daily life; it is important to control the stability and activity of such macromolecules. Therefore, the most promising route for enhancement in stability and activity is immobilizing proteins on different support materials. Furthermore, large surface area and surface functional groups are the important features that are required for a better support system. These features of graphene oxide (GO) and reduced graphene oxide (RGO) makes them ideal support materials for protein immobilization. Studies show the successful formation of GO/RGO-protein complexes with enhancement in structural/thermal stability due to various interactions at the nano-bio interface and their utilization in various functional applications. The present review focuses on protein immobilization using GO/RGO as solid support materials. Moreover, we also emphasized on basic underlying mechanism and interactions (hydrophilic, hydrophobic, electrostatic, local protein-protein, hydrogen bonding and van der Walls) between protein and GO/RGO which influences structural stability and activity of enzymes/proteins. Furthermore, GO/RGO-protein complexes are utilized in various applications such as biosensors, bioimaging and theranostic agent, targeted drug delivery agents, and nanovectors for drug and protein delivery.

Nanoparticle-induced inflammation and fibrosis in ex vivo murine precision-cut liver slices and effects of nanoparticle exposure conditions

Chronic exposure and accumulation of persistent nanomaterials by cells have led to safety concerns on potential long-term effects induced by nanoparticles, including chronic inflammation and fibrosis. With this in mind, we used murine precision-cut liver tissue slices to test potential induction of inflammation and onset of fibrosis upon 72 h exposure to different nanomaterials (0–200 µg/ml). Tissue slices were chosen as an advanced ex vivo 3D model to better resemble the complexity of the in vivo tissue environment, with a focus on the liver where most nanomaterials accumulate. Effects on the onset of fibrosis and inflammation were investigated, with particular care in optimizing nanoparticle exposure conditions to tissue. Thus, we compared the effects induced on slices exposed to nanoparticles in the presence of excess free proteins (in situ), or after corona isolation. Slices exposed to daily-refreshed nanoparticle dispersions were used to test additional effects due to ageing of the dispersions. Exposure to amino-modified polystyrene nanoparticles in serum-free conditions led to strong inflammation, with stronger effects with daily-refreshed dispersions. Instead, no inflammation was observed when slices were exposed to the same nanoparticles in medium supplemented with serum to allow corona formation. Similarly, no clear signs of inflammation nor of onset of fibrosis were detected after exposure to silica, titania or carboxylated polystyrene in all conditions tested. Overall, these results show that liver slices can be used to test nanoparticle-induced inflammation in real tissue, and that the exposure conditions and ageing of the dispersions can strongly affect tissue responses to nanoparticles.

Graphene-Based Scaffolds for Regenerative Medicine

Leading-edge regenerative medicine can take advantage of improved knowledge of key roles played, both in stem cell fate determination and in cell growth/differentiation, by mechano-transduction and other physicochemical stimuli from the tissue environment. This prompted advanced nanomaterials research to provide tissue engineers with next-generation scaffolds consisting of smart nanocomposites and/or hydrogels with nanofillers, where balanced combinations of specific matrices and nanomaterials can mediate and finely tune such stimuli and cues. In this review, we focus on graphene-based nanomaterials as, in addition to modulating nanotopography, elastic modulus and viscoelastic features of the scaffold, they can also regulate its conductivity. This feature is crucial to the determination and differentiation of some cell lineages and is of special interest to neural regenerative medicine. Hereafter we depict relevant properties of such nanofillers, illustrate how problems related to their eventual cytotoxicity are solved via enhanced synthesis, purification and derivatization protocols, and finally provide examples of successful applications in regenerative medicine on a number of tissues.

Biological effects of formation of protein corona onto nanoparticles

Administration of nanomaterials based medicinal and drug carrier systems into systemic circulation brings about interaction of blood components e.g. albumin and globulin proteins with these nanosystems. These blood or serum proteins either get loosely attached over these nanocarriers and form soft protein corona or are tightly adsorbed over nanoparticles and hard protein corona formation occurs. Formation of protein corona has significant implications over a wide array of physicochemical and medicinal attributes. Almost all pharmacological, toxicological and carrier characteristics of nanoparticles get prominently touched by the protein corona formation. It is this interaction of nanoparticle protein corona that decides and influences fate of nanomaterials-based systems. In this article, authors reviewed several diverse aspects of protein corona formation and its implications on various possible outcomes in vivo and in vitro. A brief description regarding formation and types of protein corona has been included along with mechanisms and pharmacokinetic, pharmacological behavior and toxicological profiles of nanoparticles has been described. Finally, significance of protein corona in context of its in vivo and in vitro behavior, involvement of biomolecules at nanoparticle plasma interface and other interfaces and effects of protein corona on biocompatibility characteristics have also been touched upon.

Modeling better in vitro models for the prediction of nanoparticle toxicity: a review

Exposure to nanoparticles (NPs) is plausible in real life due to ambient particulate exposure or development of nanotechnologies, hence the evaluation of NP toxicity as well as mechanism-based studies are necessary. The in vitro models allow rapid testing of NP toxicity, but it is required that the developed in vitro models are reliable to reflect the toxicity of NPs. In this review, we discussed the principles to model better in vitro models to predict the toxicity of NPs based on our own experiences and works of literature. We suggested that in vitro nanotoxicological studies should consider (1) using normal cells because the commonly used cancer cell lines might not reflect the toxicity of NPs to normal tissues; (2) the possible influence of biological molecules to reflect the toxicity of NPs in a biological microenvironment; (3) the influence of pathophysiological conditions to mimic the responses of NPs under different in vivo conditions; and (4) developing advanced tissue-based models to reflect the responses of tissues/organs to NPs. It is our hope that this review may provide useful information for the future design of in vitro nanotoxicological studies.

Construction of a Mesoporous Polydopamine@GO/Cellulose Nanofibril Composite Hydrogel with an Encapsulation Structure for Controllable Drug Release and Toxicity Shielding

The development of intelligent and multifunctional hydrogels having photothermal properties, good mechanical properties, sustained drug release abilities with low burst release, antibacterial properties, and biocompatibility is highly desirable in the biomaterial field. Herein, mesoporous polydopamine (MPDA) nanoparticles wrapped with graphene oxide (GO) were physically cross-linked in cellulose nanofibril (CNF) hydrogel to obtain a novel MPDA@GO/CNF composite hydrogel for controllable drug release. MPDA nanoparticles exhibited a high drug loading ratio (up to 35 wt %) for tetracycline hydrochloride (TH). GO was used to encapsulate MPDA nanoparticles for extending the drug release time and reinforcing the physical strength of the obtained hydrogel. The mechanical strength of the as-fabricated MPDA@GO/CNF composite hydrogel was five times greater compared to that of the pure CNF hydrogel. Drug release experiments demonstrated that burst release behavior was significantly reduced by adding MPDA@GO. The drug release time of the MPDA@GO/CNF composite hydrogel was 3 times and 7.2 times longer than that of the polydopamine/CNF hydrogel and pure CNF hydrogel, respectively. The sustained and controlled drug release behaviors of the composite hydrogel were highly dependent on the proportion of MPDA and GO. Moreover, the rate of drug release could be accelerated by near-infrared (NIR) light irradiation and pH value change. The drug release kinetics of the as-prepared composite hydrogel was well described by the Korsmeyer-Peppas model, and the drug release mechanism of TH from the composite hydrogel was anomalous transport. Importantly, this carefully designed MPDA@GO/CNF composite hydrogel showed good biocompatibility through an in vitro cytotoxicity test. In particular, the toxicity of GO was well shielded by the CNF hydrogel. Therefore, this novel MPDA@GO/CNF composite hydrogel with an encapsulation structure for controllable drug release and toxicity shielding of GO could be used as a very promising controlled drug delivery carrier, which may have potential applications for chemical and physical therapies.

Graphene: An Antibacterial Agent or a Promoter of Bacterial Proliferation?

Graphene materials (GMs) are being investigated for multiple microbiological applications because of their unique physicochemical characteristics including high electrical conductivity, large specific surface area, and robust mechanical strength. In the last decade, studies on the interaction of GMs with bacterial cells appear conflicting. On one side, GMs have been developed to promote the proliferation of electroactive bacteria on the surface of electrodes in bioelectrochemical systems or to accelerate interspecies electron transfer during anaerobic digestion. On the other side, GMs with antibacterial properties have been synthesized to prevent biofilm formation on membranes for water treatment, on medical equipment, and on tissue engineering scaffolds. In this review, we discuss the mechanisms and factors determining the positive or negative impact of GMs on bacteria. Furthermore, we examine the bacterial growth-promoting and antibacterial applications of GMs and debate their practicability.

Engineering the surface of graphene oxide with bovine serum albumin for improved biocompatibility in Caenorhabditis elegans

Graphene oxide (GO) has been extensively studied for its potential biomedical applications. However, its potential risk associated with the interactions of GO in a biological system hampers its biomedical applications. Therefore, there is an urgent need to enhance the biocompatibility of GO. In the present study, we decorated the surface of GO with bovine serum albumin (GO-BSA) to mitigate the in vivo toxic properties of GO. An in vivo model Caenorhabditis elegans has been used to study the potential protective effect of BSA decoration in mitigating GO induced toxicity. The BSA decoration on the surface of GO prevents the acute and prolonged toxicity induced by GO in primary and secondary organs by maintaining normal intestinal permeability, defecation behavior, development, and reproduction. Notably, GO-BSA treatment at 0.5-100 mg L^-1 does not affect the intracellular redox status and lifespan of C. elegans. Reporter gene expression analysis revealed that exposure to GO-BSA (100 mg L^-1) did not significantly influence the nuclear accumulation and expression patterns of DAF-16/FOXO and SKN-1/Nrf2 transcription factors and their downstream target genes sod-3, hsp-16.2, ctl-1,2,3, gcs-1, and gst-4 when compared to exposure to pristine GO. Also, quantitative real-time PCR results showed that GO-BSA did not alter the expression of genes involved in regulating DNA damage checkpoints (cep-1, hus-1 and egl-1) and core signaling pathways of apoptosis (ced-4, ced-3 and ced-9), in contrast to GO treatment. All these findings will have an impact on the future development of safer nanomaterial formulations of graphene and graphene-based materials for environmental and biomedical applications.

Graphene oxide improves postoperative cognitive dysfunction by maximally alleviating amyloid beta burden in mice

Rationale: Graphene oxide (GO) based nanomaterials have shown potential for the diagnosis and treatment of amyloid-β (Aβ)-related diseases, mainly on Alzheimer's disease (AD). However, these nanomaterials have limitations. How GO is beneficial to eliminate Aβ burden, and its physiological function in Aβ-related diseases, still needs to be investigated. Moreover, postoperative cognitive dysfunction (POCD) is an Aβ-related common central nervous system complication, however, nanomedicine treatment is lacking.

Methods: To evaluate the effects of GO on Aβ levels, HEK293T-APP-GFP and SHSY5Y-APP-GFP cells are established. Intramedullary fixation surgery for tibial fractures under inhalation anesthesia is used to induce dysfunction of fear memory in mice. The fear memory of mice is assessed by fear conditioning test.

Results: GO treatment maximally alleviated Aβ levels by simultaneously reducing Aβ generation and enhancing its degradation through inhibiting β-cleavage of amyloid precursor protein (APP) and improving endosomal Aβ delivery to lysosomes, respectively. In postoperative mice, the hippocampal Aβ levels were significantly increased and hippocampal-dependent fear memory was impaired. However, GO administration significantly reduced hippocampal Aβ levels and improved the cognitive function of the postoperative mice.

Conclusion: GO improves fear memory of postoperative mice by maximally alleviating Aβ accumulation, providing new evidence for the application of GO-based nanomedicines in Aβ-related diseases.

Dual effect of 2D WS2 nanoparticles on the lysozyme conformation

In the present work we studied the effect of 2D WS₂ nanoparticles on the conformational changes in lysozyme protein at different pH values (2.0-11.5). The contributions of various structural conformations (α-helix, β-sheets parallel and antiparallel, unordered structure and side groups) were determined by decomposition of Amid I absorbance bands. The 2D WS₂ were shown to have different impact on secondary structure depending on pH of the solution and protein concentration. The amyloid fibril presence was confirmed with confocal microscopy enhanced by gold support, and fluorescent spectroscopy with amyloid-sensitive dye Thioflavin T. Our data show that WS₂ can both inhibit and stimulate amyloid formation. Additionally, we have also reported an unusual spectroscopic behavior displayed by lysozyme, indicated by narrowing of Amide I and Amide II bands at pH 2.5 and 3.5 when incubated with 2D WS2 nanoparticles.

Tuning the binding behaviors of a protein YAP65WW domain on graphenic nano-sheets with boron or nitrogen atom doping

In recent years, nanomaterials have attracted considerable research attention for biological and medical related applications due to their well-recognized physical and chemical properties. However, the deep understanding of the binding process at the protein-nanomaterial interface is essential to solve the concern of nano-toxicity. Here, we study the interactions between the recently reported graphenic nano-sheets, BC3 and C3N, and a prototypical protein (YAP65WW domain) via atomistic molecular dynamics simulations. Our simulations reveal that elemental doping is an effective way to tune the binding characteristics of YAP65WW with two nanomaterials. While YAP65WW can be attracted by two nanomaterials, the BC3 sheet is less able to disrupt the protein structure than C3N. From the energy point of view, this is because protein residues demonstrate a binding preference with the trend from electron rich nitrogen to electron deficient boron. Structural analyses of the bio-nano interface revealed the formation of an ordered water shell on the BC3 surface, which was compatible to the crystal pattern of BC3. When a protein binds with BC3, these interfacial water molecules protect the protein from being disrupted. We suggest that elemental doping is efficient to produce fruitful biological-effects of graphenic nanomaterials, which make it a prospective solution for the future design and fabrication of advanced nanomaterials with desired function.

Protein corona: Dr. Jekyll and Mr. Hyde of nanomedicine

Nanomedicine is an interdisciplinary field of research, comprising science, engineering, and medicine. Many are the clinical applications of nanomedicine, such as molecular imaging, medical diagnostics, targeted therapy, and image-guided surgery. Despite major advances during the past 20 years, many efforts must be done to understand the complex behavior of nanoparticles (NPs) under physiological conditions, the kinetic and thermodynamic principles, involved in the rational design of NP. Once administrated in physiological environment, NPs interact with biomolecules and they are surrounded by protein corona (PC) or biocorona. PC can trigger an immune response, affecting NPs toxicity and targeting capacity. This review aims to provide a detailed description of biocorona and of parameters that are able to control PC formation and composition. Indeed, the review provides an overview about the role of PC in the modulation of both cytotoxicity and immune response as well as in the control of targeting capacity.

Graphene oxide sheets and quantum dots inhibit α-synuclein amyloid formation by different mechanisms

Aggregation and amyloid formation of the 140-residue presynaptic and intrinsically disordered protein α-synuclein (α-syn) is a pathological hallmark of Parkinson's disease (PD). Understanding how α-syn forms amyloid fibrils, and investigations of agents that can prevent their formation is therefore important. We demonstrate herein that two types of graphene oxide nanoparticles (sheets and quantum dots) inhibit α-syn amyloid formation by different mechanisms mediated via differential interactions with both monomers and fibrils. We have used thioflavin-T fluorescence assays and kinetic analysis, circular dichroism, dynamic light scattering, fluorescence spectroscopy and atomic force microscopy to asses the kinetic nature and efficiency of this inhibitory effect. We show that the two types of graphene oxide nanoparticles alter the morphology of α-syn fibrils, disrupting their interfilament assembly and the resulting aggregates therefore consist of single protofilaments. Our results further show that graphene oxide sheets reduce the aggregation rate of α-syn primarily by sequestering of monomers, thereby preventing primary nucleation and elongation. Graphene quantum dots, on the other hand, interact less avidly with both monomers and fibrils. Their aggregation inhibitory effect is primarily related to adsorption of aggregated species and reduction of secondary processes, and they can thus not fully prevent aggregation. This fine-tuned and differential effect of graphene nanoparticles on amyloid formation shows that rational design of these nanomaterials has great potential in engineering materials that interact with specific molecular events in the amyloid fibril formation process. The findings also provide new insight into the molecular interplay between amyloidogenic proteins and graphene-based nanomaterials in general, and opens up their potential use as agents to manipulate fibril formation.

Polyelectrolyte stiffness on gold nanorods mediates cell membrane damage

Charge and surface chemistry of gold nanorods (AuNRs) are often considered the predictive factors for cell membrane damage. Unfortunately, extensive research on AuNR passivated with polyelectrolyte (PE) ligand shell (AuNR-PE) has hitherto left a vital knowledge gap between the mechanical stability of the ligand shell and the cytotoxicity of AuNR-PEs. Here, the agreement between unbiased coarse-grained molecular dynamics (CGMD) simulation and empirical outcomes on hemolysis of red blood cells by AuNR-PEs demonstrates for the first time, a direct impact of the mechanical stability of the PE shell passivating the AuNRs on the lipid membrane rupture. Such mechanical stability is ultimately modulated by the rigidity of the PE components. The CGMD simulation results also reveal the mechanism where the PE chain adsorbs near the surface of the lipid bilayer without penetrating the hydrophobic core of the bilayer, which allows the hydrophobic AuNR core to be in direct contact with the hydrophobic interior of the lipid bilayer, thereby perforating the lipid membrane to induce membrane damage.

Toxicity and mechanism of mesoporous silica nanoparticles in eyes

The study on the safety of nanomaterials in eyes is still in its early stages. In this study, we put our focus on the effect of one important nanoparticle feature - large surface area - to assess eye safety. To this end, mesoporous silica nanoparticles (MSiNPs) were for the first time employed as a model to evaluate their toxicity in eyes. The porosity of the MSiNPs endows them with a large surface area and the ability to attach to surrounding chemical or biological molecules, further enhancing their surface reactivity and toxic effects. Therefore, to better mimic MSiNP exposure in real environments, we also introduced other hazardous substances such as silver ions (Ag+) to the system and then investigated their synergistic nanotoxicity. Our results showed that the exposure to MSiNPs-Ag+ and even Ag+ at a safe dose, resulted in more significant toxicity than the MSiNPs alone, as evidenced from cell viability, apoptosis, reactive oxygen species (ROS) production, and DNA damage experiments. RNA-Sequencing analysis revealed that the mRNA surveillance signalling pathway plays a unique role in regulating MSiNPs-Ag+-induced cytotoxicity. Besides this, severe corneal damage and dry eye were observed in rat models upon exposure to MSiNPs-Ag+ compared to MSiNPs. Most importantly, we also proposed a protein corona-based therapy to treat MSiNP-induced corneal disease, where the corneal damage could be rescued by fetal bovine serum (FBS) treatment.

Antibacterial activity of graphene oxide nanosheet against multidrug resistant superbugs isolated from infected patients

Graphene oxide (GO) is a derivative of graphene nanosheet which is the most promising material of the decade in biomedical research. In particular, it has been known as an antimicrobial nanomaterial with good biocompatibility. In this study, we have synthesized and characterize GO and checked its antimicrobial property against different Gram-negative and Gram-positive multidrug drug resistant (MDR) hospital superbugs grown in solid agar-based nutrient plates with and without human serum through the utilization of agar well diffusion method, live/dead fluorescent staining and genotoxicity analysis. No significant changes in antibacterial activity were found in these two different conditions. We also compare the bactericidal capability of GO with some commonly administered antibiotics and in all cases the degree of inhibition is found to be higher. The data presented here are novel and show that GO is an effective bactericidal agent against different superbugs and can be used as a future antibacterial agent.

Comparative study of nanoparticle uptake and impact in murine lung, liver and kidney tissue slices

To determine responses to nanoparticles in a more comprehensive way, current efforts in nanosafety aim at combining the analysis of multiple endpoints and comparing outcomes in different models. To this end, here we used tissue slices from mice as 3D ex vivo models and performed for the first time a comparative study of uptake and impact in liver, lung, and kidney slices exposed under the same conditions to silica, carboxylated and amino-modified polystyrene. In all organs, only exposure to amino-modified polystyrene induced toxicity, with stronger effects in kidneys and lungs. Uptake and distribution studies by confocal microscopy confirmed nanoparticle uptake in all slices, and, in line with what observed in vivo, preferential accumulation in the macrophages. However, uptake levels in kidneys were minimal, despite the strong impact observed when exposed to the amino-modified polystyrene. On the contrary, nanoparticle uptake and accumulation in macrophages were particularly evident in lung slices. Thus, tissue digestion was used to recover all cells from lung slices at different exposure times and to determine by flow cytometry detailed uptake kinetics in lung macrophages and all other cells, confirming higher uptake by the macrophages. Finally, the expression levels of a panel of targets involved in inflammation and macrophage polarization were measured to determine potential effects induced in lung and liver tissue. Overall, this comparative study allowed us to determine uptake and impact of nanoparticles in real tissue and identify important differences in outcomes in the organs in which nanoparticles distribute.

Understanding the Nano-Bio Interactions and the Corresponding Biological Responses

Due to the increasing amount of work being put into the development of nanotechnology, the field of nanomaterials holds great promise for revolutionizing biomedicine. However, insufficient understanding of nanomaterial-biological microenvironment (nano-bio) interactions hinders the clinical translation of nanomedicine. Therefore, a systematic understanding of nano-bio interaction is needed for the intelligent design of safe and effective nanomaterials for biomedical applications. In this review, we summarize the latest experimental and theoretical developments in the fields of nano-bio interfaces and corresponding biological outcomes from the perspective of corona and redox reactions. We also show that nano-bio interaction can offer a variety of multifunctional platforms with a broad range of applications in the field of biomedicine. The potential challenges and opportunities in the study of nano-bio interfaces are also provided.

Graphene-based 2D constructs for enhanced fibroblast support

Complex skin wounds have always been a significant health and economic problem worldwide due to their elusive and sometimes poor or non-healing conditions. If not well-treated, such wounds may lead to amputation, infections, cancer, or even death. Thus, there is a need to efficiently generate multifunctional skin grafts that address a wide range of skin conditions, including non-healing wounds, and enable the regeneration of new skin tissue. Here, we propose studying pristine graphene and two of its oxygen-functionalized derivatives-high and low-oxygen graphene films-as potential substrates for skin cell proliferation and differentiation. Using BJ cells (human foreskin-derived fibroblasts) to represent basic skin cells, we show that the changes in surface properties of pristine graphene due to oxygen functionalization do not seem to statistically impact the normal proliferation and maturation of skin cells. Our results indicate that the pristine and oxidized graphenes presented relatively low cytotoxicity to BJ fibroblasts and, in fact, support their growth and bioactivity. Therefore, these graphene films could potentially be integrated into more complex skin regenerative systems to support skin regeneration. Because graphene's surface can be relatively easily functionalized with various chemical groups, this finding presents a major opportunity for the development of various composite materials that can act as active components in regenerative applications such as skin regeneration.

The interaction between nanoparticles-protein corona complex and cells and its toxic effect on cells

Once nanoparticles (NPs) contact with the biological fluids, the proteins immediately adsorb onto their surface, forming a layer called protein corona (PC), which bestows the biological identity on NPs. Importantly, the NPs-PC complex is the true identity of NPs in physiological environment. Based on the affinity and the binding and dissociation rate, PC is classified into soft protein corona, hard protein corona, and interfacial protein corona. Especially, the hard PC, a protein layer relatively stable and closer to their surface, plays particularly important role in the biological effects of the complex. However, the abundant corona proteins rarely correspond to the most abundant proteins found in biological fluids. The composition profile, formation and conformational change of PC can be affected by many factors. Here, the influence factors, not only the nature of NPs, but also surface chemistry and biological medium, are discussed. Likewise, the formed PC influences the interaction between NPs and cells, and the associated subsequent cellular uptake and cytotoxicity. The uncontrolled PC formation may induce undesirable and sometimes opposite results: increasing or inhibiting cellular uptake, hindering active targeting or contributing to passive targeting, mitigating or aggravating cytotoxicity, and stimulating or mitigating the immune response. In the present review, we discuss these aspects and hope to provide a valuable reference for controlling protein adsorption, predicting their behavior in vivo experiments and designing lower toxicity and enhanced targeting nanomedical materials for nanomedicine.

Effect of Protein Corona on The Transfection Efficiency of Lipid-Coated Graphene Oxide-Based Cell Transfection Reagents

Coating graphene oxide nanoflakes with cationic lipids leads to highly homogeneous nanoparticles (GOCL NPs) with optimised physicochemical properties for gene delivery applications. In view of in vivo applications, here we use dynamic light scattering, micro-electrophoresis and one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis to explore the bionano interactions between GOCL/DNA complexes (hereafter referred to as "grapholipoplexes") and human plasma. When exposed to increasing protein concentrations, grapholipoplexes get covered by a protein corona that evolves with protein concentration, leading to biocoronated complexes with modified physicochemical properties. Here, we show that the formation of a protein corona dramatically changes the interactions of grapholipoplexes with four cancer cell lines: two breast cancer cell lines (MDA-MB and MCF-7 cells), a malignant glioma cell line (U-87 MG) and an epithelial colorectal adenocarcinoma cell line (CACO-2). Luciferase assay clearly indicates a monotonous reduction of the transfection efficiency of biocoronated grapholipoplexes as a function of protein concentration. Finally, we report evidence that a protein corona formed at high protein concentrations (as those present in in vivo studies) promotes a higher capture of biocoronated grapholipoplexes within degradative intracellular compartments (e.g., lysosomes), with respect to their pristine counterparts. On the other hand, coronas formed at low protein concentrations (human plasma = 2.5%) lead to high transfection efficiency with no appreciable cytotoxicity. We conclude with a critical assessment of relevant perspectives for the development of novel biocoronated gene delivery systems.