Biomolecular coronas provide the biological identity of nanosized materials

mRNA lipid nanoparticle phase transition

Crucial for mRNA-based vaccines are the composition, structure, and properties of lipid nanoparticles (LNPs) as their delivery vehicle. Using all-atom molecular dynamics simulations as a computational microscope, we provide an atomistic view of the structure of the Comirnaty vaccine LNP, its molecular organization, physicochemical properties, and insight in its pH-driven phase transition enabling mRNA release at atomistic resolution. At physiological pH, our simulations suggest an oil-like LNP core that is composed of the aminolipid ALC-0315 and cholesterol (ratio 72:28). It is surrounded by a lipid monolayer formed by distearoylphosphatidylcholine, ALC-0315, PEGylated lipids, and cholesterol at a ratio of 22:9:6:63. Protonated aminolipids enveloping mRNA formed inverted micellar structures that provide a shielding and likely protection from environmental factors. In contrast, at low pH, the Comirnaty lipid composition instead spontaneously formed lipid bilayers that display a high degree of elasticity. These pH-dependent lipid phases suggest that a change in pH of the environment upon LNP transfer to the endosome likely acts as trigger for cargo release from the LNP core by turning aminolipids inside out, thereby destabilizing both the LNP shell and the endosomal membrane.

Red Blood Cell Membrane-Camouflaged Gold Nanoparticles for Treatment of Melanoma

Background

Patients with melanoma have poor response and low long-term survival to conventional cisplatin (CP). Recently, biomimetic nanoparticles have played a significant role in tumor therapy. The purpose of this study was to mechanistically evaluate the effect of red blood cell membrane camouflaged gold nanoparticles loaded with CP (RBCm@AuNPs-CP) on enhancing chemotherapy in melanoma.

Methods

Treated B16-F10 cells with RBCm@AuNPs-CP, the antimelanoma effect in vitro was explored by detecting cell viability, apoptosis rate, level of reactive oxygen species (ROS), and singlet oxygen. RBCm@AuNPs-CP was injected into the melanoma-bearing mice via tail vein, and the target-ability, therapeutic effect, and toxicity were detected in melanoma tumor-bearing mice.

Results

RBCm@AuNPs-CP had an antiproliferation and apoptosis-inducing effect on B16-F10 cells, which might be mediated by oxidative stress of ROS, and its effect was significantly enhanced compared with the CP treatment group. In vivo experiments suggested the same outcome, with better target-ability of RBCm@AuNPs-CP.

Conclusion

The erythrocyte camouflage nanosystem RBCm@AuNPs-CP exhibited well passive tumor target-ability and promoted apoptosis of melanocytes by inducing ROS. RBCm@AuNPs-CP as a novel safe and effective targeted drug delivery system may provide a promising choice for the treatment of melanoma.

Surface charge influences protein corona, cell uptake and biological effects of carbon dots

Carbon dots are emerging nanoparticles (NPs) with tremendous applications, especially in the biomedical field. Herein is reported the first quantitative proteomic analysis of the protein corona formed on CDs with different surface charge properties. Four CDs were synthesized from citric acid and various amine group-containing passivation reagents, resulting in cationic NPs with increasing zeta (ζ)-potential and density of positive charges. After CD contact with serum, we show that protein corona identity is influenced by CD surface charge properties, which in turn impacts CD uptake and viability loss in macrophages. In particular, CDs with high ζ-potential (>+30 mV) and charge density (>2 μmol mg^-1) are the most highly internalized, and their cell uptake is strongly correlated with a corona enriched in vitronectin, fibulin, fetuin, adiponectin and alpha-glycoprotein. On the contrary, CDs with a lower ζ-potential (+11 mV) and charge density (0.01 μmol mg^-1) are poorly internalized, while having a corona with a very different protein signature characterized by a high abundance of apolipoproteins (APOA1, APOB and APOC), albumin and hemoglobin. These data illustrate how corona characterization may contribute to a better understanding of CD cellular fate and biological effects, and provide useful information for the development of CDs for biomedical applications.

Multi-Omics Analysis Reveals the Unexpected Immune Regulatory Effects of Arsenene Nanosheets in Tumor Microenvironment

Arsenene, a two-dimensional (2D) monoelemental layered nanosheet composed of arsenic, was recently reported to feature outstanding anticancer activities. However, the specific biological mechanism of action remains unknown. In this work, we extensively analyzed the mechanism of arsenene in vivo and in vitro and discovered the unexpected immune regulatory capability of arsenene for the first time. Analysis of cell phenotypes in tumor microenvironment by single-cell RNA sequencing revealed that arsenene remodeled the tumor microenvironment by recruiting a high proportion of anticancer immune cells to eliminate the tumor. Mechanistically, arsenene significantly activated T cell receptor signaling pathways to produce antitumor immune cells while inhibiting DNA replication and TCA cycle pathways of tumor cells in vivo. Further proteomic analysis on tumor cells revealed that arsenene induced reactive oxygen species production and oxidative stress damage by targeting thioredoxin TXNL1. The overloaded reactive oxygen species (ROS) further triggered endoplasmic reticulum stress responses to release damage-associated molecular patterns (DAMPs) and "eat-me" signals from dying tumor cells, leading to the activation of antigen-presenting processes to induce the subsequent effector tumor-specific CD8⁺ T cell immune responses. This unexpected discovery indicated for the first time that 2D inorganic nanomaterials could effectively activate direct anticancer immune responses, suggesting arsenene as a promising candidate nanomedicine for future cancer immunotherapy.

Protein Desorption Kinetics Depends on the Timescale of Observation

The presence of so-called reversible and irreversible protein adsorption on solid surfaces is well documented in the literature and represents the basis for the development of nanoparticles and implant materials to control interactions in physiological environments. Here, using a series of complementary single-molecule tracking approaches appropriate for different timescales, we show that protein desorption kinetics is much more complex than the traditional reversible-irreversible binary picture. Instead, we find that the surface residence time distribution of adsorbed proteins transitions from power law to exponential behavior when measured over a large range of timescales (10^-2-10⁶ s). A comparison with macroscopic results obtained using a quartz crystal microbalance suggested that macroscopic measurements have generally failed to observe such nonequilibrium phenomena because they are obscured by ensemble-averaging effects. These findings provide new insights into the complex phenomena associated with protein adsorption and desorption.

Chirality-Dependent Dynamic Evolution of the Protein Corona on the Surface of Quantum Dots

Elucidating the biological behavior of engineered nanoparticles, for example, the protein corona, is important for the development of safe and efficient nanomedicine, but our current understanding is still limited due to its highly dynamic nature and lack of adequate analytical tools. In the present work, we demonstrate the establishment of a fluorescence resonance energy transfer (FRET)-based platform for monitoring the dynamic evolution behavior of the protein corona in complex biological media. With human serum albumin and lysozyme as the model serum proteins, the protein exchange process of the preformed corona on the surface of chiral quantum dots (QDs) upon feeding either individual protein or human serum was monitored in situ by FRET. Important parameters characterizing the evolution process of protein corona could be obtained upon quantitative analysis of FRET data. Further combining real-time FRET monitoring with gel electrophoresis experiments revealed that the nature of the protein initially adsorbed on the surface of QDs significantly affects the subsequent dynamic exchange behavior of the protein corona. Furthermore, our results also revealed that only a limited proportion of proteins are involved in the protein exchange, and the exchange process exhibits a significant dependence on the surface chirality of QDs. This work demonstrates the feasibility of FRET as a powerful tool to exploit the dynamic evolution process of the protein corona, which can provide theoretical guidance for further design of advanced nanomaterials for biomedical applications.

Novel Antibacterial, Cytotoxic and Catalytic Activities of Silver Nanoparticles Synthesized from Acidophilic Actinobacterial SL19 with Evidence for Protein as Coating Biomolecule

Silver nanoparticles (AgNPs) have potential applications in medicine, photocatalysis, agriculture, and cosmetic fields due to their unique physicochemical properties and strong antimicrobial activity. Here, AgNPs were synthesized using actinobacterial SL19 strain, isolated from acidic forest soil in Poland, and confirmed by UV-vis and FTIR spectroscopy, TEM, and zeta potential analysis. The AgNPs were polydispersed, stable, spherical, and small, with an average size of 23 nm. The FTIR study revealed the presence of bonds characteristic of proteins that cover nanoparticles. These proteins were then studied by using liquid chromatography with tandem mass spectrometry (LC-MS/ MS) and identified with the highest similarity to hypothetical protein and porin with molecular masses equal to 41 and 38 kDa, respectively. Our AgNPs exhibited remarkable antibacterial activity against Escherichia coli and Pseudomonas aeruginosa. The combined, synergistic action of these synthesized AgNPs with commercial antibiotics (ampicillin, kanamycin, streptomycin, and tetracycline) enabled dose reductions in both components and increased their antimicrobial efficacy, especially in the case of streptomycin and tetracycline. Furthermore, the in vitro activity of the AgNPs on human cancer cell lines (MCF-7, A375, A549, and HepG2) showed cancer-specific sensitivity, while the genotoxic activity was evaluated by Ames assay, which revealed a lack of mutagenicity on the part of nanoparticles in Salmonella Typhimurium TA98 strain. We also studied the impact of the AgNPs on the catalytic and photocatalytic degradation of methyl orange (MO). The decomposition of MO was observed by a decrease in intensity of absorbance within time. The results of our study proved the easy, fast, and efficient synthesis of AgNPs using acidophilic actinomycete SL19 strain and demonstrated the remarkable potential of these AgNPs as anticancer and antibacterial agents. However, the properties and activity of such particles can vary by biosynthesized batch.

Solution properties of spherical gold nanoparticles with grafted DNA chains from simulation and theory

There has been a rapidly growing interest in the use of functionalized Au nanoparticles (NPs) as platforms in multiple applications in medicine and manufacturing. The sensing and targeting characteristics of these NPs, and the realization of precisely organized structures in manufacturing applications using such NPs, depend on the control of their surface functionalization. NP functionalization typically takes the form of polymer grafted layers, and a detailed knowledge of the chemical and structural properties of these layers is required to molecularly engineer the particle characteristics for specific applications. However, the prediction and experimental determination of these properties to enable the rational engineering of these particles is a persistent problem in the development of this class of materials. To address this situation, molecular dynamic simulations were performed based on a previously established coarse-grained single-stranded DNA (ssDNA) model to determine basic solution properties of model ssDNA-grafted NP-layers under a wide range of conditions. In particular, we emphasize the calculation of the hydrodynamic radius for ssDNA-grafted Au NPs as a function of structural parameters such as ssDNA length, NP core size, and surface coverage. We also numerically estimate the radius of gyration and the intrinsic viscosity of these NPs, which in combination with hydrodynamic radius estimates, provide valuable information about the fluctuating structure of the grafted polymer layers. We may then understand the origin of the commonly reported variation in effective NP "size" by different measurement methods, and then exploit this information in connection to material design and characterization in connection with the ever-growing number of applications utilizing polymer-grafted NPs.

Lipoprotein interactions with water-soluble NIR-II emitting aza-BODIPYs boost the fluorescence signal and favor selective tumor targeting

Following intravenous administration, the interaction of fluorescent exogenous molecules with circulating endogenous transporters can influence their photophysical properties as well as their fate and distribution, and possibly their recognition by different cell types. This type of interaction can be used to optimize the drug delivery but also the imaging properties of a compound of interest. In this study, we investigated the behavior of SWIR-WAZABY-01 fluorophore, a water-soluble aza-BODIPY dye emitting in the NIR-II region, both in vitro and in vivo. While the fluorescence emission of SWIR-WAZABY-01 was weak in aqueous solutions, it was intensely magnified in plasma (∼ ×30). Further analyses using lipoprotein gel electrophoresis and ultracentrifugation revealed interactions between SWIR-WAZABY-01 and plasma lipoproteins in vitro and ex vivo, in particular with LDL. The tumor uptake mechanism of SWIR-WAZABY-01 was investigated based on the presence of low-density lipoprotein (LDL) receptors and passive tumor uptake. Overall, we found that SWIR-WAZABY-01 interacts with lipoproteins enhancing their NIR-II fluorescence emission, and driving the tumor accumulation with regards to the expression of lipoprotein receptors (LDLR, SR-BI). Moreover, SWIR-WAZABY-01, by exploiting endogenous lipoproteins, arises as a new, potent and relevant tool to efficiently label LDL involved in pathologies.

Role of Nanomaterials in COVID-19 Prevention, Diagnostics, Therapeutics, and Vaccine Development

Facing the deadly pandemic caused by the SARS-CoV-2 virus all over the globe, it is crucial to devote efforts to fighting and preventing this infectious virus. Nanomaterials have gained much attention after the approval of lipid nanoparticle-based COVID-19 vaccines by the United States Food and Drug Administration (USFDA). In light of increasing demands for utilizing nanomaterials in the management of COVID-19, this comprehensive review focuses on the role of nanomaterials in the prevention, diagnostics, therapeutics, and vaccine development of COVID-19. First, we highlight the variety of nanomaterials usage in the prevention of COVID-19. We discuss the advantages of nanomaterials as well as their uses in the production of diagnostic tools and treatment methods. Finally, we review the role of nanomaterials in COVID-19 vaccine development. This review offers direction for creating products based on nanomaterials to combat COVID-19.

Stem cell membrane-coated abiotic nanomaterials for biomedical applications

Nanoscale materials have been extensively employed for diagnostic and therapeutic purposes. However, the developed nanosystems still suffer from some limitations, namely the rapid elimination by the immune system, lack of targeting to specific cells, and insufficient biocompatibility. Therefore, novel strategies based upon a biomimetic approach have received attention to improving the pharmacokinetics and safety profile of nanosystems. One promising strategy is the application of a biomimetic coating consisting of cell membranes derived from different cell types onto nanoparticle cores. Stem cells have been investigated to develop targeted nanodevices owing to their excellent intrinsic tissue-specific homing features, protecting them from the immune system to reach the sites of inflammation. This targeting ability is conferred by a surface repertoire of stem cell-associated biomolecules. Such nanoscopical materials offer sustained circulation and boosted drug accumulation at target sites, augmenting therapeutic efficacy and safety. Additionally, the coating of nanoparticles with cell membranes acts as a camouflage mechanism to increase their circulation time. The current review explores the particular features of stem cell membrane coating as multifunctional biomimetic surface functionalization agents to camouflage nanoparticle cores. Biomedical applications of engineered stem cell membrane-coated nanoparticles, challenges in clinical translation, and their future prospects are addressed.

The Yin and Yang of the protein corona on the delivery journey of nanoparticles

Nanoparticles-based drug delivery systems have attracted significant attention in biomedical fields because they can deliver loaded cargoes to the target site in a controlled manner. However, tremendous challenges must still be overcome to reach the expected targeting and therapeutic efficacy in vivo. These challenges mainly arise because the interaction between nanoparticles and biological systems is complex and dynamic and is influenced by the physicochemical properties of the nanoparticles and the heterogeneity of biological systems. Importantly, once the nanoparticles are injected into the blood, a protein corona will inevitably form on the surface. The protein corona creates a new biological identity which plays a vital role in mediating the bio-nano interaction and determining the ultimate results. Thus, it is essential to understand how the protein corona affects the delivery journey of nanoparticles in vivo and what we can do to exploit the protein corona for better delivery efficiency. In this review, we first summarize the fundamental impact of the protein corona on the delivery journey of nanoparticles. Next, we emphasize the strategies that have been developed for tailoring and exploiting the protein corona to improve the transportation behavior of nanoparticles in vivo. Finally, we highlight what we need to do as a next step towards better understanding and exploitation of the protein corona. We hope these insights into the "Yin and Yang" effect of the protein corona will have profound implications for understanding the role of the protein corona in a wide range of nanoparticles.

In situ analysis of nanoparticle soft corona and dynamic evolution

How soft corona, the protein corona’s outer layer, contributes to biological identity of nanomaterials is largely because capturing protein composition of the soft corona in situ remains challenging. We herein develop an in situ Fishing method that can monitor the dynamic formation of protein corona on ultra-small chiral Cu₂S nanoparticles (NPs) allowing us to directly separate and identify the corona protein composition. Our method detects spatiotemporal processes in the evolution of hard and soft coronas on chiral NPs, revealing subtle differences in NP − protein interactions even within several minutes. This study highlights the importance of in situ and dynamic analysis of soft/hard corona, provides insights into the role of soft corona in mediating biological responses of NPs, and offers a universal strategy to characterize soft corona to guide the rational design of biomedical nanomaterials.

Characterizing the soft protein corona on nanoparticles i.e. the outer layer of the corona, remains a longstanding challenge. Here, the authors develop an in situ method to monitor the dynamic processes of multilayered corona formation and evolution that offers a universal strategy to characterize the soft corona proteome.

Harnessing Protein Corona for Biomimetic Nanomedicine Design

Nanoparticles (NPs) are usually treated as multifunctional agents combining several therapeutical applications, like imaging and targeting delivery. However, clinical translation is still largely hindered by several factors, and the rapidly formed protein corona on the surface of NPs is one of them. The formation of protein corona is complicated and irreversible in the biological environment, and protein corona will redefine the “biological identity” of NPs, which will alter the following biological events and therapeutic efficacy. Current understanding of protein corona is still limited and incomplete, and in many cases, protein corona has adverse impacts on nanomedicine, for instance, losing targeting ability, activating the immune response, and rapid clearance. Due to the considerable role of protein corona in NPs’ biological fate, harnessing protein corona to achieve some therapeutic effects through various methods like biomimetic approaches is now treated as a promising way to meet the current challenges in nanomedicine such as poor pharmacokinetic properties, off-target effect, and immunogenicity. This review will first introduce the current understanding of protein corona and summarize the investigation process and technologies. Second, the strategies of harnessing protein corona with biomimetic approaches for nanomedicine design are reviewed. Finally, we discuss the challenges and future outlooks of biomimetic approaches to tune protein corona in nanomedicine.

Absorption, distribution, metabolism, excretion and toxicity of microplastics in the human body and health implications

Microplastics (MPs; <5 mm) in the biosphere draws public concern about their potential health impacts. Humans are potentially exposed to MPs via ingestion, inhalation, and dermal contact. Ingestion and inhalation are the two major exposure pathways. An adult may consume approximately 5.1 × 10³ items from table salts and up to 4.1 × 10⁴ items via drinking water annually. Meanwhile, MP inhalation intake ranges from 0.9 × 10⁴ to 7.9 × 10⁴ items per year. The intake of MPs would be further distributed in different tissues and organs of humans depending on their sizes. The excretion has been discussed with the possible clearance ways (e.g., urine and feces). The review summarized the absorption, distribution, metabolic toxicity and excretion of MPs together with the attached chemicals. Moreover, the potential implications on humans are also discussed from in vitro and in vivo studies, and connecting the relationship between the physicochemical properties and the potential risks. This review will contribute to a better understanding of MPs as culprits and/or vectors linking to potential human health hazards, which will help outline the promising areas for further revealing the possible toxicity pathways.

Inhibition of Mitochondrial Biosynthesis Using a "Right-Side-Out" Membrane-Camouflaged Micelle to Facilitate the Therapeutic Effects of Shikonin on Triple-Negative Breast Cancer

The mitochondria represent a potential target for the treatment of triple-negative breast cancer (TNBC) and shikonin (SK) has shown remarkable therapeutic effects on TNBC. Herein, it is found that SK possesses potent inhibitory effects on mitochondrial biogenesis via targeting polymerase gamma (POLG). However, its application is restricted by its poor aqueous solubility and stability, and therefore, a biomimetic micelle to aid with tumor lesion accumulation and mitochondria-targeted delivery of SK is designed. A folic acid (FA) conjugated polyethylene glycol derivative (FA-PEG-FA) is inserted onto the external membranes of red blood cells (FP-RBCm) to prepare a "right-side-out" RBCm-camouflaged cationic micelle (ThTM/SK@FP-RBCm). Both FP-RBCm coating and a triphenylphosphine (TPP) moiety on the periphery of micelles contribute to tumor lesion distribution, receptor-mediated cellular uptake, and electrostatic attraction-dependent mitochondrial targeting, thereby maximizing inhibitory effects on mitochondrial biosynthesis in TNBC cells. Intravenous administration of ThTM/SK@FP-RBCm leads to profound inhibition of tumor growth and lung metastasis in a TNBC mouse model with no obvious toxicity. This work highlights the mitochondria-targeted delivery of SK using a "right-side-out" membrane-camouflaged micelle for the inhibition of mitochondrial biogenesis and enhanced therapeutic effects on TNBC.

Cytotoxicity and Genotoxicity of Polystyrene Micro- and Nanoplastics with Different Size and Surface Modification in A549 Cells

Background

Micro- and nano-sized plastics (MPs and NPs) have become an environmental issue of global concern due to their small size, strong bio-permeability and high specific surface area. However, few studies have assessed the effect of polystyrene MPs and NPs on human lung cells. In this research, we evaluated the cytotoxicity and genotoxicity of polystyrene (PS) MPs and NPs with different sizes (2 μm and 80 nm) and surface modification (carboxy and amino functionalized polystyrene, pristine polystyrene) in A549 cells.

Methods

The zeta potential and hydrodynamic particle size of five types of PS plastic solutions were measured by dynamic light scattering, and their morphology and degree of aggregation were observed by scanning electron microscopy. After incubation of the PS plastics with A549 cells, the uptake and toxicity of the cells were assessed by fluorescence microscopy, laser scanning confocal microscopy, flow cytometry, MTT, micronucleus formation assay, and reactive oxygen species.

Results

The cytotoxicity and genotoxicity of A549 cells caused by nano-level PS is more serious than that of micro-level. Compared with unmodified PS-NPs, more surface-functionalized PS-NPs were found inside the cells, especially the accumulation of PS-NH₂. Cell viability and the induction of micronuclei (MN) are appreciably impacted in a dose-dependent way. Compared with pristine PS-NPs, functionalized PS-NPs showed stronger cell viability inhibitory ability, and induced more MN scores.

Conclusion

This study shows that the intrinsic size properties and surface modification of PS plastics, the interaction between PS plastics and the receiving medium, intracellular accumulation are critical factors for evaluating the toxicological influences of PS plastics on humans.

Selective detection of tartaric acid using amino acid interlinked silver nanoparticles as a colorimetric probe

A variety of biomolecules with different functional groups play critical roles in almost all the processes occurring in living cells. Interaction of metallic nanoparticles (NPs) with various biomolecules generates a layer of molecules on their surface, and this biomolecular rich layer formed on the NP surface is described as a "biomolecular corona". The physicochemical properties of the NPs, including size, adsorption affinity, and charge on the particles' surfaces are the major factors influencing the characteristics of this corona. The formation of various biomolecular corona has been studied well, whereas the amino acid corona is relatively new by exploring their stability. In the present study, a novel formation of an amino acid corona with a fundamental interaction mechanism for a selective detection procedure using a colorimetric platform has been proposed. Herein, amino acid-coated silver NPs (AgNPs) have been used as a template with spectroscopic (steady state UV-Vis, FTIR) and imaging (HR-TEM, DLS) techniques. Our findings demonstrated that among different amino acid coronas, glutathione (GSH) stabilized AgNPs show a rapid reaction with tartaric acid. The extent and thermodynamics of the formed complex between the GSH/AgNPs and tartaric acid have also been studied and this suggested that the complex formed is spontaneous and energy releasing in nature.

In Situ Characterization of the Protein Corona of Nanoparticles In Vitro and In Vivo

A new theoretical framework that enables the use of differential dynamic microscopy (DDM) in fluorescence imaging mode to quantify in situ protein adsorption onto nanoparticles (NP) while simultaneously monitoring for NP aggregation is proposed. This methodology is used to elucidate the thermodynamic and kinetic properties of the protein corona (PC) in vitro and in vivo. The results show that protein adsorption triggers particle aggregation over a wide concentration range and that the formed aggregate structures can be quantified using the proposed methodology. Protein affinity for polystyrene (PS) NPs is observed to be dependent on particle concentration. For complex protein mixtures, this methodology identifies that the PC composition changes with the dilution of serum proteins, demonstrating a Vroman effect never quantitatively assessed in situ on NPs. Finally, DDM allows monitoring of the evolution of the PC in vivo. This results show that the PC composition evolves significantly over time in zebrafish larvae, confirming the inherently dynamic nature of the PC. The performance of the developed methodology allows to obtain quantitative insights into nano-bio interactions in a vast array of physiologically relevant conditions that will serve to further improve the design of nanomedicine.

Circulating tumor cell isolation for cancer diagnosis and prognosis

Circulating tumor cells (CTCs) are tumor cells that shed from the primary tumor and intravasate into the peripheral blood circulation system responsible for metastasis. Sensitive detection of CTCs from clinical samples can serve as an effective tool in cancer diagnosis and prognosis through liquid biopsy. Current CTC detection technologies mainly reply on the biomarker-mediated platforms including magnetic beads, microfluidic chips or size-sensitive microfiltration which can compromise detection sensitivity due to tumor heterogeneity. A more sensitive, biomarker independent CTCs isolation technique has been recently developed with the surface-charged superparamagnetic nanoprobe capable of different EMT subpopulation CTC capture from 1 mL clinical blood. In this review, this new strategy is compared with the conventional techniques on biomarker specificity, impact of protein corona, effect of glycolysis on cell surface charge, and accurate CTC identification. Correlations between CTC enumeration and molecular profiling in clinical blood and cancer prognosis are provided for clinical cancer management.

A label-free technique to quantify and visualize gold nanoparticle accumulation at the single-cell level

Despite their wide bioapplications, potential health risks of gold nanoparticles (AuNPs) remain unclear. As a determinant of their risks, AuNP accumulation within a cell population is subject to cell-to-cell heterogeneity. Methods to simultaneously quantify and visualize intracellular AuNPs at the single-cell level are, however, lacking. Here we developed a novel label-free technique, based on hyperspectral imaging with enhanced darkfield microscopy (HSI-DFM), to visualize and quantify AuNP accumulation at the single-cell level. The identification ability of the hyperspectral libraries derived from extra- and intracellular AuNPs was compared. The spectral number in the libraries was optimized to maximize their identification ability while minimizing the identification time. In addition, a filtration method was established to merge spectral libraries from different cell lines based on their similarity. The intracellularly accumulated AuNPs as determined by HSI-DFM well correlated with those detected by inductively coupled plasma mass spectrometry. This validation allowed us to calculate the intracellular concentration of AuNPs at the single-cell level and to monitor the accumulation kinetics of AuNPs in living cells. The label-free method developed herein can be applied to other types of AuNPs differing in their physicochemical properties as well as other NPs, as long as they are detectable by HSI-DFM.

Unveiling adsorption generality in polymeric macromolecules

Unveiling a general law for adsorption within macromolecules sets an important step forward in the design of nanomaterials with tunable and controllable properties. Reaching such a generalised control would have an important outcome in a plethora of possible fields, from biomedical applications up to materials science. In fact, the definition of classes regrouping adsorbing macromolecules with different geometrical or chemical properties would enormously simplify the design of controllable adsorbing materials, especially when geometrical or chemical constraints are set by the particular application. In this work we derive, through a combination of Scaling Theories and Molecular Dynamics Simulations, a general law for adsorption of spherical non-deformable colloidal nanoparticles within polymeric macromolecules of different geometries. Starting from the case of adsorption of a single colloid within macromolecular systems, we extend the results to the case in which finite adsorption takes place. We then derive simple predictions linking the adsorption potential to general properties of classes of macromolecules, and introduce a set of measurable quantities that can be exploited as an indirect measurement for loading.

Biocorona modulates the inflammatory response induced by gold nanoparticles in human epidermal keratinocytes

The functional activities of gold nanoparticles (AuNPs) on biological systems depend on their physical-chemical properties and their surface functionalizations. Within a biological environment and depending on their surface characteristics, NPs can adsorb biomolecules (mostly proteins) present in the microenvironment, thereby forming a dynamic biomolecular corona on the surface. The presence of this biocorona changes the physical-chemical and functional properties of the NPs and how it interacts with cells. Here, we show that primary human epidermal keratinocytes (HEK) exposed in culture to branched polyethyleneimine (BPEI)-AuNPs, but not to lipoic acid (LA)-AuNPs, show potent particle uptake, decreased viability and enhanced production of inflammatory factors, while the presence of a human plasma-derived biocorona decreased NPs uptake and rescued cells from BPEI-AuNP-induced cell death. The mechanistic study revealed that the intracellular oxidative level greatly increased after the BPEI-AuNPs treatment, and the transcriptomic analysis showed that the dominant modulated pathways were related to oxidative stress and an antioxidant response. The stress level measured by flow cytometry also showed a significant decrease in the presence of a biocorona. Further anaylsis discovered that nuclear factor erythroid-2 related factor (Nrf2), a major regulator of anti-oxidant and anti-inflammatory gene, as the key factor related to the AuNPs induced oxidative stress and inflammation. This study provides futher understanding into the mechanisms on how NPs-induced cellular stress and reveals the protective effects of a biocorona on inflammatory responses in HEK at the molecular level, which provides important insights into the biological responses of AuNPs and their biocorona.

Concentration and composition of the protein corona as a function of incubation time and serum concentration: an automated approach to the protein corona

Nanoparticles in contact with proteins form a "corona" of proteins adsorbed on the nanoparticle surface. Subsequent biological responses are then mediated by the adsorbed proteins rather than the bare nanoparticles. The use of nanoparticles as nanomedicines and biosensors would be greatly improved if researchers were able to predict which specific proteins will adsorb on a nanoparticle surface. We use a recently developed automated workflow with a liquid handling robot and low-cost proteomics to determine the concentration and composition of the protein corona formed on carboxylate-modified iron oxide nanoparticles (200 nm) as a function of incubation time and serum concentration. We measure the concentration of the resulting protein corona with a colorimetric assay and the composition of the corona with proteomics, reporting both abundance and enrichment relative to the fetal bovine serum (FBS) proteins used to form the corona. Incubation time was found to be an important parameter for corona concentration and composition at high (100% FBS) incubation concentrations, with only a slight effect at low (10%) FBS concentrations. In addition to these findings, we describe two methodological advances to help reduce the cost associated with protein corona experiments. We have automated the digest step necessary for proteomics and measured the variability between triplicate samples at each stage of the proteomics experiments. Overall, these results demonstrate the importance of understanding the multiple parameters that influence corona formation, provide new tools for corona characterization, and advance bioanalytical research in nanomaterials.

Lipid nanoparticle-based mRNA vaccines in cancers: Current advances and future prospects

Messenger RNA (mRNA) vaccines constitute an emerging therapeutic method with the advantages of high safety and efficiency as well as easy synthesis; thus, they have been widely used in various human diseases, especially in malignant cancers. However, the mRNA vaccine technology has some limitations, such as instability and low transitive efficiency in vivo, which greatly restrict its application. The development of nanotechnology in the biomedical field offers new strategies and prospects for the early diagnosis and treatment of human cancers. Recent studies have demonstrated that Lipid nanoparticle (LNP)-based mRNA vaccines can address the poor preservation and targeted inaccuracy of mRNA vaccines. As an emerging cancer therapy, mRNA vaccines potentially have broad future applications. Unlike other treatments, cancer mRNA vaccines provide specific, safe, and tolerable treatments. Preclinical studies have used personalized vaccines to demonstrate the anti-tumor effect of mRNA vaccines in the treatment of various solid tumors, including colorectal and lung cancer, using these in a new era of therapeutic cancer vaccines. In this review, we have summarized the latest applications and progress of LNP-based mRNA vaccines in cancers, and discussed the prospects and limitations of these fields, thereby providing novel strategies for the targeted therapy of cancers.

Multicolor Super-Resolution Microscopy of Protein Corona on Single Nanoparticles

Nanoparticles represent a promising class of material for nanomedicine and molecular biosensing. The formation of a protein corona due to nonspecific particle-protein interactions is a determining factor for the biological fate of nanoparticles in vivo and strongly impacts the performance of nanoparticles when used as biosensors. Nonspecific interactions are usually highly heterogeneous, yet little is known about the heterogeneity of the protein corona that may lead to inter- and intraparticle differences in composition and protein distribution. Here, we present a super-resolution microscopic approach to study the protein corona on single silica nanoparticles and subsequent cellular interactions using multicolor stimulated emission depletion (STED) microscopy. We demonstrate that STED resolves structural features of protein corona on single particles including the distribution on the particle surface and the degree of protein internalization in porous particles. Using multicolor measurements of multiple labeled protein species, we determine the composition of the protein corona at the single-particle level. We quantify particle-to-particle differences in the composition and find that the composition is considerably influenced by the particle geometry. In a subsequent cellular uptake measurement, we demonstrate multicolor STED of protein corona on single particles internalized by cells. Our study shows that STED microscopy opens the window toward mechanistic understanding of protein coronas and aids in the rational design of nanoparticles as nanomedicines and biosensors.

Advanced Light Source Analytical Techniques for Exploring the Biological Behavior and Fate of Nanomedicines

Exploration of the biological behavior and fate of nanoparticles, as affected by the nanomaterial-biology (nano-bio) interaction, has become progressively critical for guiding the rational design and optimization of nanomedicines to minimize adverse effects, support clinical translation, and aid in evaluation by regulatory agencies. Because of the complexity of the biological environment and the dynamic variations in the bioactivity of nanomedicines, in-situ, label-free analysis of the transport and transformation of nanomedicines has remained a challenge. Recent improvements in optics, detectors, and light sources have allowed the expansion of advanced light source (ALS) analytical technologies to dig into the underexplored behavior and fate of nanomedicines in vivo. It is increasingly important to further develop ALS-based analytical technologies with higher spatial and temporal resolution, multimodal data fusion, and intelligent prediction abilities to fully unlock the potential of nanomedicines. In this Outlook, we focus on several selected ALS analytical technologies, including imaging and spectroscopy, and provide an overview of the emerging opportunities for their applications in the exploration of the biological behavior and fate of nanomedicines. We also discuss the challenges and limitations faced by current approaches and tools and the expectations for the future development of advanced light sources and technologies. Improved ALS imaging and spectroscopy techniques will accelerate a profound understanding of the biological behavior of new nanomedicines. Such advancements are expected to inspire new insights into nanomedicine research and promote the development of ALS capabilities and methods more suitable for nanomedicine evaluation with the goal of clinical translation.

Chiral FA Conjugated CdTe/CdS Quantum Dots for Selective Cancer Ablation

Inducing apoptosis in cancer cells is considered a potential therapeutic mechanism underlying cancers. Here, chiral folic acid (FA) conjugated Cys-CdTe/CdS quantum dots (QDs) conjugated with a cancer-targeting ligand were fabricated to induce apoptosis in vivo. Ligand-induced chirality mechanism for FA-Cys-CdTe/CdS QDs was discussed, which is verified by density functional theory (DFT) simulation. Interestingly, we found that the circular dichroism (CD) signals of chiral QDs can effectively distinguish breast cancer cells from normal cells, where a sharp decrease in CD signal and absorption intensity can be seen. Notably, chiral FA-Cys-CdTe/CdS QDs showed significant apoptosis-inducing ability after the release of mitochondrial apoptotic factors. Furthermore, in vivo experiments showed that chiral FA-Cys-CdTe/CdS QDs provide an efficient cancer ablation through the apoptosis process with negligible toxicity, demonstrating their great potential utility in targeted anticancer agent for future clinic application.

Anti-PEG Antibodies Boosted in Humans by SARS-CoV-2 Lipid Nanoparticle mRNA Vaccine

Humans commonly have low level antibodies to poly(ethylene) glycol (PEG) due to environmental exposure. Lipid nanoparticle (LNP) mRNA vaccines for SARS-CoV-2 contain small amounts of PEG, but it is not known whether PEG antibodies are enhanced by vaccination and what their impact is on particle-immune cell interactions in human blood. We studied plasma from 130 adults receiving either the BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) mRNA vaccines or no SARS-CoV-2 vaccine for PEG-specific antibodies. Anti-PEG IgG was commonly detected prior to vaccination and was significantly boosted a mean of 13.1-fold (range 1.0-70.9) following mRNA-1273 vaccination and a mean of 1.78-fold (range 0.68-16.6) following BNT162b2 vaccination. Anti-PEG IgM increased 68.5-fold (range 0.9-377.1) and 2.64-fold (0.76-12.84) following mRNA-1273 and BNT162b2 vaccination, respectively. The rise in PEG-specific antibodies following mRNA-1273 vaccination was associated with a significant increase in the association of clinically relevant PEGylated LNPs with blood phagocytes ex vivo. PEG antibodies did not impact the SARS-CoV-2 specific neutralizing antibody response to vaccination. However, the elevated levels of vaccine-induced anti-PEG antibodies correlated with increased systemic reactogenicity following two doses of vaccination. We conclude that PEG-specific antibodies can be boosted by LNP mRNA vaccination and that the rise in PEG-specific antibodies is associated with systemic reactogenicity and an increase of PEG particle-leukocyte association in human blood. The longer-term clinical impact of the increase in PEG-specific antibodies induced by lipid nanoparticle mRNA vaccines should be monitored. It may be useful to identify suitable alternatives to PEG for developing next-generation LNP vaccines to overcome PEG immunogenicity in the future.

Importance of Standardizing Analytical Characterization Methodology for Improved Reliability of the Nanomedicine Literature

Understanding the interaction between biological structures and nanoscale technologies, dubbed the nano-bio interface, is required for successful development of safe and efficient nanomedicine products. The lack of a universal reporting system and decentralized methodologies for nanomaterial characterization have resulted in a low degree of reliability and reproducibility in the nanomedicine literature. As such, there is a strong need to establish a characterization system to support the reproducibility of nanoscience data particularly for studies seeking clinical translation. Here, we discuss the existing key standards for addressing robust characterization of nanomaterials based on their intended use in medical devices or as pharmaceuticals. We also discuss the challenges surrounding implementation of such standard protocols and their implication for translation of nanotechnology into clinical practice. We, however, emphasize that practical implementation of standard protocols in experimental laboratories requires long-term planning through integration of stakeholders including institutions and funding agencies.

Aquatic organisms modulate the bioreactivity of engineered nanoparticles: focus on biomolecular corona

The increased use of nanoparticle (NP)-enabled materials in everyday-life products have raised concerns about their environmental implications and safety. This motivated the extensive research in nanoecotoxicology showing the possibility that NPs could cause harm to the aquatic organisms if present at high concentrations. By contrast, studies dealing with influence that organisms could exert on the fate and thus effects of NPs are still very rare. Drawing on the existing up-to-date knowledge we critically discuss the formation of biomolecular corona as one of the mechanisms by which organisms exerted control on the NPs fate in the aquatic and biotic environments. We focused the formation of corona by exogeneous and endogenous biomolecules and illustrated the discussion with the specific example of phytoplankton and aquatic invertebrate species. We highlighted the necessity to incorporate the concept of biomolecular corona within more general framework considering the feedback of aquatic organisms and the control they exert in shaping the fate and impact of NPs in the aquatic and biological environment. In our view such broader perspective will contribute to get novel insights into the drivers of environmental transformations of NPs and their mechanisms, which are important in environmental risk assessment.

Amphotericin B-PEG Conjugates of ZnO Nanoparticles: Enhancement Antifungal Activity with Minimal Toxicity

Amphotericin B (AMB) is commonly used to treat life-threatening systemic fungal infections. AMB formulations that are more efficient and less nephrotoxic are currently unmet needs. In the current study, new ZnO-PEGylated AMB (ZnO-AMB-PEG) nanoparticles (NPs) were synthesized and their antifungal effects on the Candida spp. were investigated. The size and zeta potential values of AMB-PEG and ZnO-AMB-PEG NPs were 216.2 ± 26.9 to 662.3 ± 24.7 nm and −11.8 ± 2.02 to −14.2 ± 0.94 mV, respectively. The FTIR, XRD, and EDX spectra indicated that the PEG-enclosed AMB was capped by ZnO, and SEM images revealed the ZnO distribution on the surface NPs. In comparison to ZnO-AMB NPs and free AMB against C.albicans and C.neoformans, ZnO-AMB-PEG NPs significantly reduced the MIC and MFC. After a week of single and multiple dosage, the toxicity was investigated utilizing in vitro blood hemolysis, in vivo nephrotoxicity, and hepatic functions. ZnO-AMB-PEG significantly lowered WBC count and hematocrit concentrations when compared to AMB and ZnO-AMB. RBC count and hemoglobulin content, on the other hand, were unaltered. ZnO-AMB-PEG considerably lowered creatinine and blood urea nitrogen (BUN) levels when compared to AMB and ZnO-AMB. The difference in liver function indicators was determined to be minor by all formulae. These findings imply that ZnO-AMB-PEG could be utilized in the clinic with little nephrotoxicity, although more research is needed to determine the formulation’s in vivo efficacy.

Navigations of the targeting pathway of nanomedicines towards tumor

INTRODUCTION

Nanomedicines (NMs) have emerged as a promising approach for revolutionizing cancer treatment outcomes, mainly due to their benefits in the tumor targeted delivery of therapeutics. The preferential accumulation of NMs in tumor has been widely verified by macroscopical technologies. Accordingly, several classic and emerging targeting mechanisms have been proposed to support the tumor-specific delivery of NMs. The targeting mechanism has been a topic of intensive interest and controversy in the field of NMs development. Especially, the mechanisms by which NMs target tumor remain elusive.

AREA COVERED

This topical review mainly discussed the evolution of the targeting mechanisms, crucial issues associated with each mechanism, and confused debates among the mechanisms. The targeting mechanisms of tumor-specific NMs discussed here include the enhanced permeability and retention (EPR) effect, protein corona-mediated targeting delivery, circulating cell mediated transportation, and transcytosis.

EXPERT OPINION

It is of great significance for ultimate clinical translation to have more comprehensive considerations on the mechanism driving the pathway of NMs toward tumors. Our thoughts in this review are expected to provide comprehensive understanding on the mechanisms and elicit thorough explorations on new mechanism to renovate the knowledge framework of NMs delivery.

Biomolecular Corona Stability in Association with Plasma Cholesterol Level

Biomolecular corona is spontaneously formed on the surface of nanoparticles (NPs) when they are in contact with biological fluids. It plays an important role in the colloidal stability of NPs, which is of importance for most of their medical applications and toxicity assessment. While typical studies use either blood plasma or serum from a pooled biobank, it is unclear whether differences in the media, such as cholesterol level or protein concentration, might affect the NP colloidal stability and corona composition. In this study, the silica corona was prepared at particularly low plasma concentrations (3%, v/v–1.98 mg/mL) to identify the critical roles of the protein mass/NP surface ratio and the level of plasma cholesterol on the corona protein pattern and particle stability. While depending on the plasma dilution factor, the corona protein composition could be controlled by keeping the protein/NP constant. The NP colloidal stability was found to strongly correlate with the level of cholesterol in human plasma, particularly due to the high enrichment of high-density lipoprotein (HDL) and low-density lipoprotein (LDL) in the corona. A cohort study on plasma samples from individuals with known cholesterol levels was performed to highlight that association, which could be relevant for all corona systems enriched with the LDL.

Recent advances in erythrocyte membrane-camouflaged nanoparticles for the delivery of anti-cancer therapeutics

INTRODUCTION

Red blood cell (or erythrocyte) membrane-camouflaged nanoparticles (RBC-NPs) not only have a superior circulation life and do not induce accelerated blood clearance, but also possess special functions, which offers great potential in cancer therapy.

AREAS COVERED

This review focuses on the recent advances of RBC-NPs for delivering various agents to treat cancers in light of their vital role in improving drug delivery. Meanwhile, the construction and in vivo behavior of RBC-NPs are discussed to provide an in-depth understanding of the basis of RBC-NPs for improved cancer drug delivery.

EXPERT OPINION

Although RBC-NPs are quite prospective in delivering anti-cancer therapeutics, they are still in their infancy stage and many challenges need to be overcome for successful translation into the clinic. The preparation and modification of RBC membranes, the optimization of coating methods, the scale-up production and the quality control of RBC-NPs, and the drug loading and release should be carefully considered in the clinical translation of RBC-NPs for cancer therapy.

Engineering a Nano/Biointerface for Cell and Organ-Selective Drug Delivery

The field of nanomedicine has rapidly grown in the past decades. Although a few nanomedicines are available in the market for clinical use, it is still challenging to develop nanomedicine targeting tissues beyond the liver. It has been recognized that even though the nanoparticles are modified with targeting ligands, the formation of a protein corona on the surface of nanoparticles in the biological fluids results in limited progress in nanoparticle-based drug delivery to specific cells or tissues. In this Perspective, we will discuss the role of surface properties in determining the formation of the protein corona and summarize the recent progress in engineering the nano/bio interface for protein-corona-mediated cell- and organ-selective drug delivery. Moreover, current challenges in the field and insights into designing new strategies for targeting drug delivery with a better understanding of the protein corona will be discussed.

Complement-Opsonized NIR-IIb Emissive Immunotracers for Dynamically Monitoring Neutrophils in Inflammation-Related Diseases

Real-time monitoring of neutrophil dynamics is crucial for timely diagnosis and effective treatment of inflammation-related diseases, which requires a reliable tracer for in vivo tracking of neutrophils. However, immunotracers for neutrophils are extremely limited because of the difficulty in labeling the cells. Inspired by the natural biological function of the complement system, a strategy of enhancing the complement C3 opsonization of lanthanide-doped nanoparticles (LnNPs) by modulating their surface chemistry, thus developing a near infrared-IIb emissive nanotracer for neutrophils, is reported herein. Four kinds of surface-modified LnNPs are fabricated, among which phospholipids DOPG-modified LnNPs (LnNPs@PG) with weak antifouling ability and hydroxyl groups adsorb more complement C3 proteins and form covalent linkages with C3b active fragments under inflammation conditions, inducing enhanced complement C3 opsonization. Therefore, LnNPs@PG with enhanced complement C3 opsonization are capable of efficiently labeling inflammation-stimulated neutrophils in vivo through complement-receptors-mediated phagocytosis and achieve dynamic monitoring neutrophils during cutaneous wound healing and cerebral ischemia/reperfusion.

Polyglycerol and Poly(ethylene glycol) exhibit different effects on pharmacokinetics and antibody generation when grafted to nanoparticle surfaces

Poly(ethylene glycol) (PEG) is widely employed for passivating nanoparticle (NP) surfaces to prolong blood circulation and enhance localization of NPs to target tissue. However, the immune response of PEGylated NPs-including anti-PEG antibody generation, accelerated blood clearance (ABC), and loss of delivery efficacy-is of some concern, especially for treatments that require repeat administrations. Although polyglycerol (PG), which has the same ethylene oxide backbone as PEG, has received attention as an alternative to PEG for NP coatings, the pharmacokinetic and immunogenic impact of PG has not been studied systematically. Here, linear PG, hyperbranched PG (hPG), and PEG-coated polylactide (PLA) NPs with varying surface densities were studied in parallel to determine the pharmacokinetics and immunogenicity of PG and hPG grafting, in comparison with PEG. We found that linear PG imparted the NPs a stealth property comparable to PEG, while hPG-grafted NPs needed a higher surface density to achieve the same pharmacokinetic impact. While linear PG-grafted NPs induced anti-PEG antibody production in mice, they exhibited minimal accelerated blood clearance (ABC) effects due to the poor interaction with anti-PEG immunoglobulin M (IgM). Further, we observed no anti-polymer IgM responses or ABC effects for hPG-grafted NPs.

Deploying Gold Nanomaterials in Combating Multi-Drug-Resistant Bacteria

Antibiotic resistance has become a serious threat to human health due to the overuse of antibiotics. Different antibiotics are being developed to treat resistant bacteria, but the development cycle of antibiotics is hard to keep up with the high incidence of antibiotic resistance. Recent advances in antimicrobial nanomaterials have made nanotechnology a powerful solution to this dilemma. Among these nanomaterials, gold nanomaterials have excellent antibacterial efficacy and biosafety, making them alternatives to antibiotics. This review presents strategies that use gold nanomaterials to combat drug-resistant bacteria. We focus on the influence of physicochemical factors such as surface chemistry, size, and shape of gold nanomaterials on their antimicrobial properties and describe the antimicrobial applications of gold nanomaterials in medical devices. Finally, the existing challenges and future directions are discussed.

Repulsive Interactions of Eco-corona-Covered Microplastic Particles Quantitatively Follow Modeling of Polymer Brushes

The environmental fate and toxicity of microplastic particles are dominated by their surface properties. In the environment, an adsorbed layer of biomolecules and natural organic matter forms the so-called eco-corona. A quantitative description of how this eco-corona changes the particles' colloidal interactions is still missing. Here, we demonstrate with colloidal probe-atomic force microscopy that eco-corona formation on microplastic particles introduces a compressible film on the surface, which changes the mechanical behavior. We measure single particle-particle interactions and find a pronounced increase of long-range repulsive interactions upon eco-corona formation. These force-separation characteristics follow the Alexander-de Gennes (AdG) polymer brush model under certain conditions. We further compare the obtained fitting parameters to known systems like polyelectrolyte multilayers and propose these as model systems for the eco-corona. Our results show that concepts of fundamental polymer physics, like the AdG model, also help in understanding more complex systems like biomolecules adsorbed to surfaces, i.e., the eco-corona.

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

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

Quantifying impacts of titanium dioxide nanoparticles on natural assemblages of riverine phytobenthos and phytoplankton in an outdoor setting

Impacts of widespread release of engineered titanium dioxide nanoparticles (nTiO₂) on freshwater phytoplankton and phytobenthic assemblages in the field, represents a significant knowledge gap. Using outdoor experiments, we quantified impacts of nTiO₂ on phytoplankton and periphyton from UK rivers, applied at levels representative of environmentally realistic concentrations (0.05 mg/L) and hot spots of accumulation (5.0 mg/L). Addition of nTiO₂ to river water led to rapid temporal size changes in homoagglomerates and many heteroaggregates of nTiO₂ with cells in the phytoplankton, including green algae, pennate and centric diatoms, increasing settlement of some cells. Changes in phytoplankton composition were evident after 72-h resulting from a significant decline in the relative abundance of very small phytoplankton cells (1-3 μm), often accompanied by increases in centric diatoms at both concentrations. Significant changes detected in the composition of the phytobenthos after 12 days, following nTiO₂ treatments, were not evident when using benthic diatoms alone after 56 days. A lack of inhibition in the maximum quantum yield (Fv/Fm) in phytobenthos after 72-h exposures contrasted with a significant inhibition in Fv/Fm in 75% of phytoplankton samples, the highest recorded in Rutile nTiO₂ exposures at both concentrations of nTiO₂. After 12 days, strong positive stimulatory responses were recorded in the maximum relative electron transport rate (rETR_max) and the maximum non-photochemical coefficient (NPQ_max), in phytoplankton and phytobenthos samples exposed to the higher Anatase nTiO₂ concentration, were not measured in Rutile exposed biota. Collectively, these results indicate that the Rutile phase of nTiO₂ has more negative impacts on freshwater algae than the Anatase form, at specific time scales, and phytoplankton may be more impacted by nTiO₂ than phytobenthos. We caution that repeated release of nTiO₂, could lead to significant changes in riverine algal biomass and species composition, dependent on the phase and concentration of nTiO₂.

Biological Impacts of Reduced Graphene Oxide Affected by Protein Corona Formation

Applications of reduced graphene oxide (rGO) in many different areas have been gradually increasing owing to its unique physicochemical characteristics, demanding more understanding of their biological impacts. Herein, we assessed the toxicological effects of rGO in mammary epithelial cells. Because the as-synthesized rGO was dissolved in sodium cholate to maintain a stable aqueous dispersion, we hypothesize that changing the cholate concentration in the dispersion may alter the surface property of rGO and subsequently affect its cellular toxicity. Thus, four types of rGO were prepared and compared: rGO dispersed in 4 and 2 mg/mL sodium cholate, labeled as rGO and concentrated-rGO (c-rGO), respectively, and rGO and c-rGO coated with a protein corona through 1 h incubation in culture media, correspondingly named pro-rGO and pro-c-rGO. Notably, c-rGO and pro-c-rGO exhibited higher toxicity than rGO and pro-rGO and also caused higher reactive oxygen species production, more lipid membrane peroxidation, and more significant disruption of mitochondrial-based ATP synthesis. In all toxicological assessments, pro-c-rGO induced more severe adverse impacts than c-rGO. Further examination of the material surface, protein adsorption, and cellular uptake showed that the surface of c-rGO was coated with a lower content of surfactant and adsorbed more proteins, which may result in the higher cellular uptake observed with pro-c-rGO than pro-rGO. Several proteins involved in cellular redox mediation were also more enriched in pro-c-rGO. These results support the strong correlation between dispersant coating and corona formation and their subsequent cellular impacts. Future studies in this direction could reveal a deeper understanding of the correlation and the specific cellular pathways involved and help gain knowledge on how the toxicity of rGO could be modulated through surface modification, guiding the sustainable applications of rGO.

Nanoparticle elasticity affects systemic circulation lifetime by modulating adsorption of apolipoprotein A-I in corona formation

Nanoparticle elasticity is crucial in nanoparticles' physiological fate, but how this occurs is largely unknown. Using core-shell nanoparticles with a same PEGylated lipid bilayer shell yet cores differing in elasticity (45 kPa - 760 MPa) as models, we isolate the effects of nanoparticle elasticity from those of other physiochemical parameters and, using mouse models, observe a non-monotonic relationship of systemic circulation lifetime versus nanoparticle elasticity. Incubating our nanoparticles in mouse plasma provides protein coronas varying non-monotonically in composition depending on nanoparticle elasticity. Particularly, apolipoprotein A-I (ApoA1) is the only protein whose relative abundance in corona strongly correlates with our nanoparticles' blood clearance lifetime. Notably, similar results are observed when above nanoparticles' PEGylated lipid bilayer shell is changed to be non-PEGylated. This work unveils the mechanisms by which nanoparticle elasticity affects nanoparticles' physiological fate and suggests nanoparticle elasticity as a readily tunable parameter in future rational exploiting of protein corona.

Thermodynamic and Kinetic Binding Behaviors of Human Serum Albumin to Silver Nanoparticles

A nanoparticle, under biological milieu, is inclined to be combined with various biomolecules, particularly protein, generating an interfacial corona which provides a new biological identity. Herein, the binding interaction between silver nanoparticles (AgNPs) and human serum albumin (HSA) was studied with transmission electron microscopy (TEM), circular dichroism (CD), and multiple spectroscopic techniques. Due to the ground state complex formed mainly through hydrophobic interactions, the fluorescence titration method proved that intrinsic fluorescence for HSA was probably statically quenched by AgNPs. The complete thermodynamic parameters were derived, indicating that the interaction between HSA and AgNPs is an entropy-driven process. Additionally, synchronous fluorescence and CD spectrum results suggested the conformational variation it has upon binding to AgNPs and the α-helix content has HSA visibly decreased. The kinetic experiments proved the double hysteresis effect has in HSA’s binding to the AgNPs surface. Moreover, the binding has between HSA and AgNPs follows the pseudo-second-order kinetic characteristic and fits the Freundlich model for multilayer adsorption. These results facilitate the comprehension about NPs’ underlying biological effects under a physiological environment and promote the secure applications of NPs biologically and medically.

Protein corona alters the mechanisms of interaction between silica nanoparticles and lipid vesicles

The use of nanoparticles (NPs) for biomedical applications implies their delivery into the organism where they encounter biological fluids. In such biological fluids, proteins and other biomolecules adhere to the surface of the NPs forming a biomolecular corona that can alter significantly the behaviour of the nanomaterials. Here, we investigate the impact of a bovine serum albumin corona on interactions between silica nanoparticles (SNPs) of two different sizes and giant lipid vesicles. The formation of the protein corona leads to a significant increase of the hydrodynamic size of the SNPs. Confocal microscopy imaging shows that the protein corona alters the morphological response of vesicles to SNPs. In addition, Laurdan spectral imaging show that the protein corona weakens the effect of SNPs on the lipid packing in the GUV membrane. Our results demonstrate that a protein corona can change the interaction mechanism between nanoparticles and lipid membranes.