Identification of Receptor Binding to the Biomolecular Corona of Nanoparticles

Sensing with Molecularly Imprinted Membranes on Two-Dimensional Solid-Supported Substrates

Molecularly imprinted membranes (MIMs) have been a focal research interest since 1990, representing a breakthrough in the integration of target molecules into membrane structures for cutting-edge sensing applications. This paper traces the developmental history of MIMs, elucidating the diverse methodologies employed in their preparation and characterization on two-dimensional solid-supported substrates. We then explore the principles and diverse applications of MIMs, particularly in the context of emerging technologies encompassing electrochemistry, surface-enhanced Raman scattering (SERS), surface plasmon resonance (SPR), and the quartz crystal microbalance (QCM). Furthermore, we shed light on the unique features of ion-sensitive field-effect transistor (ISFET) biosensors that rely on MIMs, with the notable advancements and challenges of point-of-care biochemical sensors highlighted. By providing a comprehensive overview of the latest innovations and future trajectories, this paper aims to inspire further exploration and progress in the field of MIM-driven sensing technologies.

Preadsorbed Chymotrypsin Modulated the Composition of Protein Corona and Immunological Response

It is well-known that proteins after administration into biological environments adsorb on the surface of nanoparticles (NPs). The biological identity could be determined by protein corona, but whether and how the preadsorbed molecules impact the composition of the corona and immunological response have rarely been reported. Here, the effects of preadsorbed chymotrypsin (Chy) on forming protein corona and subsequent immunological response are reported. We find that preadsorbed Chy on the surface of AuNPs results in a protein corona with enriched immunoglobulins and reduced human serum albumin protein, which further affect the polarization of macrophages into specific phenotypes. Our study suggests that the protein surrounding the nanoparticles could affect the protein corona and immunological response, which may direct the preparation of multifunctional nanomedicine for future studies.

Genome-wide forward genetic screening to identify receptors and proteins mediating nanoparticle uptake and intracellular processing

Understanding how cells process nanoparticles is crucial to optimize nanomedicine efficacy. However, characterizing cellular pathways is challenging, especially if non-canonical mechanisms are involved. In this Article a genome-wide forward genetic screening based on insertional mutagenesis is applied to discover receptors and proteins involved in the intracellular accumulation (uptake and intracellular processing) of silica nanoparticles. The nanoparticles are covered by a human serum corona known to target the low-density lipoprotein receptor (LDLR). By sorting cells with reduced nanoparticle accumulation and deep sequencing after each sorting, 80 enriched genes are identified. We find that, as well as LDLR, the scavenger receptor SCARB1 also mediates nanoparticle accumulation. Additionally, heparan sulfate acts as a specific nanoparticle receptor, and its role varies depending on cell and nanoparticle type. Furthermore, some of the identified targets affect nanoparticle trafficking to the lysosomes. These results show the potential of genetic screening to characterize nanoparticle pathways. Additionally, they indicate that corona-coated nanoparticles are internalized via multiple receptors.

A Nanoplasmonic Assay for Point-of-Care Detection of Mannose-Binding Lectin in Human Serum

Mannose-binding lectin (MBL) activates the complement system lectin pathway and subsequent inflammatory mechanisms. The incidence and outcome of many human diseases, such as brain ischemia and infections, are associated with and influenced by the activity and serum concentrations of MBL in body fluids. To quantify MBL levels, tests based on ELISA are used, requiring several incubation and washing steps and lengthy turnaround times. Here, we aimed to develop a nanoplasmonic assay for direct MBL detection in human serum at the point of care. Our assay is based on gold nanorods (GNRs) functionalized with mannose (Man-GNRs) via an amphiphilic linker. We experimentally determined the effective amount of sugar linked to the nanorods' surface, resulting in an approximate grafting density of 4 molecules per nm2, and an average number of 11 to 13 MBL molecules binding to a single nanoparticle. The optimal Man-GNRs concentration to achieve the highest sensitivity in MBL detection was 15 μg·mL-1. The specificity of the assay for MBL detection both in simple buffer and in complex pooled human sera was confirmed. Our label-free biosensor is able to detect MBL concentrations as low as 160 ng·mL-1 within 15 min directly in human serum via a one-step reaction and by using a microplate reader. Hence, it forms the basis for a fast, noninvasive, point-of-care assay for diagnostic indications and monitoring of disease and therapy.

The biomolecular corona of nanomedicines: effects on nanomedicine outcomes and emerging opportunities

Upon administration, nanomedicines adsorb a corona of endogenous biomolecules on their surface, which can affect nanomedicine interactions with cells, targeting, and efficacy. While strategies to reduce protein binding are available, the high selectivity of the adsorbed corona is enabling novel applications, such as for biomarker discovery and rare protein identification. Additionally, the adsorbed molecules can promote interactions with specific cell receptors, thus conferring the nanomedicine new endogenous targeting capabilities. This has been reported for Onpattro, a lipid nanoparticle targeting the hepatocytes via apolipoproteins in its corona. Recently, selective organ-targeting (SORT) nanoparticles have been proposed, which exploit corona-mediated interactions to deliver nanoparticles outside the liver. Strategies for corona seeding and corona engineering are emerging to increase the selectivity of similar endogenous targeting mechanisms.

Sources of biases in the in vitro testing of nanomaterials: the role of the biomolecular corona

The biological fate of nanomaterials (NMs) is driven by specific interactions through which biomolecules, naturally adhering onto their surface, engage with cell membrane receptors and intracellular organelles. The molecular composition of this layer, called the biomolecular corona (BMC), depends on both the physical-chemical features of the NMs and the biological media in which the NMs are dispersed and cells grow. In this work, we demonstrate that the widespread use of 10% fetal bovine serum in an in vitro assay cannot recapitulate the complexity of in vivo systemic administration, with NMs being transported by the blood. For this purpose, we undertook a comparative journey involving proteomics, lipidomics, high throughput multiparametric in vitro screening, and single molecular feature analysis to investigate the molecular details behind this in vivo/in vitro bias. Our work indirectly highlights the need to introduce novel, more physiological-like media closer in composition to human plasma to produce realistic in vitro screening data for NMs. We also aim to set the basis to reduce this in vitro-in vivo mismatch, which currently limits the formulation of NMs for clinical settings.

Biomolecular Corona of Gold Nanoparticles: The Urgent Need for Strong Roots to Grow Strong Branches

Gold nanoparticles (GNPs) are largely employed in diagnostics/biosensors and are among the most investigated nanomaterials in biology/medicine. However, few GNP-based nanoformulations have received FDA approval to date, and promising in vitro studies have failed to translate to in vivo efficacy. One key factor is that biological fluids contain high concentrations of proteins, lipids, sugars, and metabolites, which can adsorb/interact with the GNP's surface, forming a layer called biomolecular corona (BMC). The BMC can mask prepared functionalities and target moieties, creating new surface chemistry and determining GNPs' biological fate. Here, the current knowledge is summarized on GNP-BMCs, analyzing the factors driving these interactions and the biological consequences. A partial fingerprint of GNP-BMC analyzing common patterns of composition in the literature is extrapolated. However, a red flag is also risen concerning the current lack of data availability and regulated form of knowledge on BMC. Nanomedicine is still in its infancy, and relying on recently developed analytical and informatic tools offers an unprecedented opportunity to make a leap forward. However, a restart through robust shared protocols and data sharing is necessary to obtain "stronger roots". This will create a path to exploiting BMC for human benefit, promoting the clinical translation of biomedical nanotools.

Surface Chemistry of Biologically Active Reducible Oxide Nanozymes

Reducible metal oxide nanozymes (rNZs) are a subject of intense recent interest due to their catalytic nature, ease of synthesis, and complex surface character. Such materials contain surface sites which facilitate enzyme-mimetic reactions via substrate coordination and redox cycling. Further, these surface reactive sites are shown to be highly sensitive to stresses within the nanomaterial lattice, the physicochemical environment, and to processing conditions occurring as part of their syntheses. When administered in vivo, a complex protein corona binds to the surface, redefining its biological identity and subsequent interactions within the biological system. Catalytic activities of rNZs each deliver a differing impact on protein corona formation, its composition, and in turn, their recognition, and internalization by host cells. Improving the understanding of the precise principles that dominate rNZ surface-biomolecule adsorption raises the question of whether designer rNZs can be engineered to prevent corona formation, or indeed to produce "custom" protein coronas applied either in vitro, and preadministration, or formed immediately upon their exposure to body fluids. Here, fundamental surface chemistry processes and their implications in rNZ material performance are considered. In particular, material structures which inform component adsorption from the application environment, including substrates for enzyme-mimetic reactions are discussed.

Nanotechnology's frontier in combatting infectious and inflammatory diseases: prevention and treatment

Inflammation-associated diseases encompass a range of infectious diseases and non-infectious inflammatory diseases, which continuously pose one of the most serious threats to human health, attributed to factors such as the emergence of new pathogens, increasing drug resistance, changes in living environments and lifestyles, and the aging population. Despite rapid advancements in mechanistic research and drug development for these diseases, current treatments often have limited efficacy and notable side effects, necessitating the development of more effective and targeted anti-inflammatory therapies. In recent years, the rapid development of nanotechnology has provided crucial technological support for the prevention, treatment, and detection of inflammation-associated diseases. Various types of nanoparticles (NPs) play significant roles, serving as vaccine vehicles to enhance immunogenicity and as drug carriers to improve targeting and bioavailability. NPs can also directly combat pathogens and inflammation. In addition, nanotechnology has facilitated the development of biosensors for pathogen detection and imaging techniques for inflammatory diseases. This review categorizes and characterizes different types of NPs, summarizes their applications in the prevention, treatment, and detection of infectious and inflammatory diseases. It also discusses the challenges associated with clinical translation in this field and explores the latest developments and prospects. In conclusion, nanotechnology opens up new possibilities for the comprehensive management of infectious and inflammatory diseases.

Impact of calcium ions at physiological concentrations on the adsorption behavior of proteins on silica nanoparticles

The adsorption of proteins on nanoparticles (NPs) largely decides the fate and bioeffects of NPs in vivo. However, bio-fluids are too complicated to directly study in them to reveal related mechanisms, and current studies on model systems often ignore some important biological factors, such as metal ions. Herein, we evaluate the effect of Ca2+ at physiological concentrations on the protein adsorption on negatively-charged silica NP (SNP50). It is found that Ca2+, as well as Mg2+ and several transition metal ions, significantly enhances the adsorption of negatively-charged proteins on SNP50. Moreover, the Ca2+-induced enhancement of protein adsorption leads to the reduced uptake of SNP50 by HeLa cells. A double-chelating mechanism is proposed for the enhanced adsorption of negatively-charged proteins by multivalent metal ions that can form 6 (or more) coordinate bonds, where the metal ions are chelated by both the surface groups of NPs and the surface residues of the adsorbed proteins. This mechanism is consistent with all experimental evidences from metal ions-induced changes of physicochemical properties of NPs to protein adsorption isotherms, and is validated with several model proteins as well as complicated serum. The findings highlight the importance of investigating the influences of physiological factors on the interaction between proteins and NPs.

Oligodendrocyte progenitor cell-specific delivery of lipid nanoparticles loaded with Olig2 synthetically modified messenger RNA for ischemic stroke therapy

The transcription factor Olig2 is highly expressed throughout oligodendroglial development and is needed for the differentiation of oligodendrocyte progenitor cells (OPCs) into oligodendrocytes and remyelination. Although Olig2 overexpression in OPCs is a possible therapeutic target for enhancing myelin repair in ischemic stroke, achieving Olig2 overexpression in vivo remains a formidable technological challenge. To address this challenge, we employed lipid nanoparticle (LNP)-mediated delivery of Olig2 synthetically modified messenger RNA (mRNA) as a viable method for in vivo Olih2 protein overexpression. Specifically, we developed CD140a-targeted LNPs loaded with Olig2 mRNA (C-Olig2) to achieve targeted Olig2 protein expression within PDGFRα+ OPCs, with the goal of promoting remyelination for ischemic stroke therapy. We show that C-Olig2 promotes the differentiation of PDGFRα+ OPCs derived from mouse neural stem cells into mature oligodendrocytes in vitro, suggesting that mRNA-mediated Olig2 overexpression is a rational approach to promote oligodendrocyte differentiation and remyelination. Furthermore, when C-Olig2 was administered to a murine model of ischemic stroke, it led to improvements in blood‒brain barrier (BBB) integrity, enhanced remyelination, and rescued learning and cognitive deficits. Our comprehensive analysis, which included bulk RNA sequencing (RNA-seq) and single-nucleus RNA-seq (snRNA-seq), revealed upregulated biological processes related to learning and memory in the brains of mice treated with C-Olig2 compared to those receiving empty LNPs (Mock). Collectively, our findings highlight the therapeutic potential of multifunctional nanomedicine targeting mRNA expression for ischemic stroke and suggest that this approach holds promise for addressing various brain diseases. STATEMENT OF SIGNIFICANCE: While Olig2 overexpression in OPCs represents a promising therapeutic avenue for enhancing remyelination in ischemic stroke, in vivo strategies for achieving Olig2 expression pose considerable technological challenges. The delivery of mRNA via lipid nanoparticles is considered aa viable approach for in vivo protein expression. In this study, we engineered CD140a-targeted LNPs loaded with Olig2 mRNA (C-Olig2) with the aim of achieving specific Olig2 overexpression in mouse OPCs. Our findings demonstrate that C-Olig2 promotes the differentiation of OPCs into oligodendrocytes in vitro, providing evidence that mRNA-mediated Olig2 overexpression is a rational strategy to foster remyelination. Furthermore, the intravenous administration of C-Olig2 into a murine model of ischemic stroke not only improved blood-brain barrier integrity but also enhanced remyelination and mitigated learning and cognitive deficits. These results underscore the promising therapeutic potential of multifunctional nanomedicine targeting mRNA expression in the context of ischemic stroke.

Nanostructured graphene oxide enriched with metallic nanoparticles as a biointerface to enhance cell adhesion through mechanosensory modifications

Nanostructuring is a process involving surface manipulation at the nanometric level, which improves the mechanical and biological properties of biomaterials. Specifically, it affects the mechanotransductive perception of the microenvironment of cells. Mechanical force conversion into an electrical or chemical signal contributes to the induction of a specific cellular response. The relationship between the cells and growth surface induces a biointerface-modifying cytophysiology and consequently a therapeutic effect. In this study, we present the fabrication of graphene oxide (GO)-based nanofilms decorated with metallic nanoparticles (NPs) as potential coatings for biomaterials. Our investigation showed the effect of decorating GO with metallic NPs for the modification of the physicochemical properties of nanostructures in the form of nanoflakes and nanofilms. A comprehensive biocompatibility screening panel revealed no disturbance in the metabolic activity of human fibroblasts (HFFF2) and bone marrow stroma cells (HS-5) cultivated on the GO nanofilms decorated with gold and copper NPs, whereas a significant cytotoxic effect of the GO nanocomplex decorated with silver NPs was demonstrated. The GO nanofilm decorated with gold NPs beneficially managed early cell adhesion as a result of the transient upregulation of α1β5 integrin expression, acceleration of cellspreading, and formation of elongated filopodia. Additionally, the cells, sensing the substrate derived from the nanocomplex enriched with gold NPs, showed reduced elasticity and altered levels of vimentin expression. In the future, GO nanocomplexes decorated with gold NPs can be incorporated in the structure of architecturally designed biomimetic biomaterials as biocompatible nanostructuring agents with proadhesive properties.

Differential cellular responses to FDA-approved nanomedicines: an exploration of albumin-based nanocarriers and liposomes in protein corona formation

Albumin nanoparticles (NPs) and PEGylated liposomes have garnered tremendous interest as therapeutic drug carriers due to their unique physicochemical properties. These unique properties also have significant effects on the composition and structure of the protein corona formed around these NPs in a biological environment. Herein, protein corona formation on albumin NPs and liposomes was simultaneously evaluated through in vitro and simulation studies. The sizes of both types of NPs increased with more negatively charged interfaces upon being introduced into fetal bovine serum. Gel electrophoresis and label-free quantitative proteomics were performed to identify proteins recruited to the hard corona, and fewer proteins were found in albumin NPs than in liposomes, which is in accordance with isothermal titration calorimetry. The cellular uptake efficiency of the two NPs significantly differed in different serum concentrations, which was further scrutinized by loading an anticancer compound into albumin NPs. The presence of the hard protein corona increased the cellular uptake of albumin NPs in comparison with liposomes. In our simulation study, a specific receptor present in the membrane was greatly attracted to the albumin-apolipoprotein E complex. Overall, this study not only evaluated protein corona formation on albumin NPs, but also made promising advancements toward albumin- and liposome-based therapeutic systems.

Multivariate Analysis of Protein-Nanoparticle Binding Data Reveals a Selective Effect of Nanoparticle Material on the Formation of Soft Corona

When nanoparticles are introduced into the bloodstream, plasma proteins accumulate at their surface, forming a protein corona. This corona affects the properties of intravenously administered nanomedicines. The firmly bound layer of plasma proteins in direct contact with the nanomaterial is called the "hard corona". There is also a "soft corona" of loosely associated proteins. While the hard corona has been extensively studied, the soft corona is less understood due to its inaccessibility to analytical techniques. Our study used dynamic light scattering to determine the dissociation constant and thickness of the protein corona formed in solutions of silica or gold nanoparticles mixed with serum albumin, transferrin or prothrombin. Multivariate analysis showed that the nanoparticle material had a greater impact on binding properties than the protein type. Serum albumin had a distinct binding pattern compared to the other proteins tested. This pilot study provides a blueprint for future investigations into the complexity of the soft protein corona, which is key to developing nanomedicines.

Protein Corona Formation on Lipid Nanoparticles Negatively Affects the NLRP3 Inflammasome Activation

The interaction between lipid nanoparticles (LNPs) and serum proteins, giving rise to a unique identification in the form of the protein corona, has been shown to be associated with novel recognition by cell receptors. The presence of the corona enveloping the nanoparticle strongly affects the interplay with immune cells. The immune responses mediated by protein corona can affect nanoparticle toxicity and targeting capabilities. But the intracellular signaling of LNPs after corona formation resulting in the change of nanoparticles' ability to provoke immune responses remains unclear. Therefore, a more systematic and delineated approach must be considered to present the correlation between corona complexes and the shift in nanoparticle immunogenicity. Here, we studied and reported the inhibiting effect of the absorbed proteins on the LNPs on the NLRP3 inflammasome activation, a key intracellular protein complex that modulates several inflammatory responses. Ionizable lipid as a component of LNP was observed to play an important role in modulating the activation of NLRP3 inflammasome in serum-free conditions. However, in the presence of serum proteins, the corona layer on LNPs caused a significant reduction in the inflammasome activation. Reduction in the lysosomal rupture after treatment with corona-LNPs significantly reduced inflammasome activation. Furthermore, a strong reduction of cellular uptake in macrophages after the corona formation was observed. On inspecting the uptake mechanisms in macrophages using transport inhibitors, lipid formulation was found to play a critical role in determining the endocytic pathways for the LNPs in macrophages. This study highlights the need to critically analyze the protein interactions with nanomaterials and their concomitant adaptability with immune cells to evaluate nano-bio surfaces and successfully design nanomaterials for biological applications.

The LDL receptor is regulated by membrane cholesterol as revealed by fluorescence fluctuation analysis

Membrane cholesterol-rich domains have been shown to be important for regulating a range of membrane protein activities. Low-density lipoprotein receptor (LDLR)-mediated internalization of cholesterol-rich LDL particles is tightly regulated by feedback mechanisms involving intracellular sterol sensors. Since LDLR plays a role in maintaining cellular cholesterol homeostasis, we explore the role that membrane domains may have in regulating LDLR activity. We expressed a fluorescent LDLR-mEGFP construct in HEK293T cells and imaged the unligated receptor or bound to an LDL/DiI fluorescent ligand using total internal reflection fluorescence microscopy. We studied the receptor's spatiotemporal dynamics using fluorescence fluctuation analysis methods. Image cross correlation spectroscopy reveals a lower LDL-to-LDLR binding fraction when membrane cholesterol concentrations are augmented using cholesterol esterase, and a higher binding fraction when the cells are treated with methyl-β-cyclodextrin) to lower membrane cholesterol. This suggests that LDLR's ability to metabolize LDL particles is negatively correlated to membrane cholesterol concentrations. We then tested if a change in activity is accompanied by a change in membrane localization. Image mean-square displacement analysis reveals that unligated LDLR-mEGFP and ligated LDLR-mEGFP/LDL-DiI constructs are transiently confined on the cell membrane, and the size of their confinement domains increases with augmented cholesterol concentrations. Receptor diffusion within the domains and their domain-escape probabilities decrease upon treatment with methyl-β-cyclodextrin, consistent with a change in receptor populations to more confined domains, likely clathrin-coated pits. We propose a feedback model to account for regulation of LDLR within the cell membrane: when membrane cholesterol concentrations are high, LDLR is sequestered in cholesterol-rich domains. These LDLR populations are attenuated in their efficacy to bind and internalize LDL. However, when membrane cholesterol levels drop, LDL has a higher binding affinity to its receptor and the LDLR transits to nascent clathrin-coated domains, where it diffuses at a slower rate while awaiting internalization.

Cholesterol modulates the physiological response to nanoparticles by changing the composition of protein corona

Nanoparticles (NPs) in biological fluids form a layer of biomolecules known as the protein corona. The protein corona has been shown to determine the biological identity and in vivo fate of NPs, but whether and how metabolites, especially disease-related small molecules, regulate the protein corona and subsequently impact NP fate in vivo is relatively poorly understood. Here we report on the effects of cholesterol on the generation of protein corona and subsequent effects. We find that high levels of cholesterol, as in hypercholesterolemia, result in a protein corona with enriched apolipoproteins and reduced complement proteins by altering the binding affinity of the proteins to the NPs. The cholesterol-mediated protein corona can induce stronger inflammatory responses to NPs in macrophages and promote the cellular uptake of NPs in hepatocytes by enhancing the recognition of lipoprotein receptors when compared with normal protein corona. The result of in vivo biodistribution assays shows that, compared with healthy mice, NPs in hypercholesterolemic mice were more likely to be delivered to the liver, spleen and brain, and less likely to be delivered to the lungs. Our findings reveal that the metabolome profile is an unexploited factor impacting the target efficacy and safety of nanomedicines, providing a way to develop personalized nanomedicines by harnessing disease-related metabolites.

Multiomics analysis of naturally efficacious lipid nanoparticle coronas reveals high-density lipoprotein is necessary for their function

In terms of lipid nanoparticle (LNP) engineering, the relationship between particle composition, delivery efficacy, and the composition of the biocoronas that form around LNPs, is poorly understood. To explore this we analyze naturally efficacious biocorona compositions using an unbiased screening workflow. First, LNPs are complexed with plasma samples, from individual lean or obese male rats, and then functionally evaluated in vitro. Then, a fast, automated, and miniaturized method retrieves the LNPs with intact biocoronas, and multiomics analysis of the LNP-corona complexes reveals the particle corona content arising from each individual plasma sample. We find that the most efficacious LNP-corona complexes were enriched with high-density lipoprotein (HDL) and, compared to the commonly used corona-biomarker Apolipoprotein E, corona HDL content was a superior predictor of in-vivo activity. Using technically challenging and clinically relevant lipid nanoparticles, these methods reveal a previously unreported role for HDL as a source of ApoE and, form a framework for improving LNP therapeutic efficacy by controlling corona composition.

Quartz Crystal Microbalance Method to Measure Nanoparticle-Receptor Interactions and Evaluate Nanoparticle Design Efficiency

Conjugation of biomolecules on the surface of nanoparticles (NPs) to achieve active targeting is widely investigated within the scientific community. However, while a basic framework of the physicochemical processes underpinning bionanoparticle recognition is now emerging, the precise evaluation of the interactions between engineered NPs and biological targets remains underdeveloped. Here, we show how the adaptation of a method currently used to evaluate molecular ligand-receptor interactions by quartz crystal microbalance (QCM) can be used to obtain concrete insights into interactions between different NP architectures and assemblies of receptors. Using a model bionanoparticle grafted with oriented apolipoprotein E (ApoE) fragments, we examine key aspects of bionanoparticle engineering for effective interactions with target receptors. We show that the QCM technique can be used to rapidly measure construct-receptor interactions across biologically relevant exchange times. We contrast random adsorption of the ligand at the surface of the NPs, resulting in no measurable interaction with target receptors, to grafted oriented constructs, which are strongly recognized even at lower graft densities. The effects of other basic parameters impacting the interaction such as ligand graft density, receptor immobilization density, and linker length were also efficiently evaluated with this technique. Dramatic changes in interaction outcomes with subtle alterations in these parameters highlight the general importance of measuring the interactions between engineered NPs and target receptors ex situ early on in the construct development process for the rational design of bionanoparticles.

Converting Nanotoxicity Data to Information Using Artificial Intelligence and Simulation

Decades of nanotoxicology research have generated extensive and diverse data sets. However, data is not equal to information. The question is how to extract critical information buried in vast data streams. Here we show that artificial intelligence (AI) and molecular simulation play key roles in transforming nanotoxicity data into critical information, i.e., constructing the quantitative nanostructure (physicochemical properties)-toxicity relationships, and elucidating the toxicity-related molecular mechanisms. For AI and molecular simulation to realize their full impacts in this mission, several obstacles must be overcome. These include the paucity of high-quality nanomaterials (NMs) and standardized nanotoxicity data, the lack of model-friendly databases, the scarcity of specific and universal nanodescriptors, and the inability to simulate NMs at realistic spatial and temporal scales. This review provides a comprehensive and representative, but not exhaustive, summary of the current capability gaps and tools required to fill these formidable gaps. Specifically, we discuss the applications of AI and molecular simulation, which can address the large-scale data challenge for nanotoxicology research. The need for model-friendly nanotoxicity databases, powerful nanodescriptors, new modeling approaches, molecular mechanism analysis, and design of the next-generation NMs are also critically discussed. Finally, we provide a perspective on future trends and challenges.

Nanoparticle-based immunotherapeutics: from the properties of nanocores to the differential effects of administration routes

The engagement with the immune system is one of the main cornerstones in the development of nanotechnologies for therapy and diagnostics. Recent advances have made possible the tuning of features like size, shape and biomolecular modifications that influence such interactions, however, the capabilities for immune modulation of nanoparticles are still not well defined and exploited. This review focuses on recent advances made in preclinical research for the application of nanoparticles to modulate immune responses, and the main features making them relevant for such applications. We review and discuss newest evidence in the field, which include in vivo experiments with an extensive physicochemical characterization as well as detailed study of the induced immune response. We emphasize the need of incorporating knowledge about immune response development and regulation in the design and application of nanoparticles, including the effect by parameters such as the administration route and the differential interactions with immune subsets.

Organismal response to micro(nano)plastics at environmentally relevant concentrations: Toxicity and the underlying mechanisms

The toxic effects of micro(nano)plastics are long-standing, flourishing and fadeless as a research topic because of its' underlying threats to the ecology and human health. Nevertheless, in most of the existing studies, some model organisms are exposed to micro(nano)plastics at a high concentration unlikely to occur in the real environment, and there is limited data available on the impact of micro(nano)plastics at environmentally relevant concentrations (ERC) on environmental organisms. To gain a better insight into micro(nano)plastic toxicity to the environmental organisms, here we integrate the related publications of micro(nano)plastic research at ERC in the past 10 years using a bibliometric analysis, and focus on the analysis of publication trends, research focuses, collaborations, and research status. In addition, we further analyze the 33 final filtered literature, and elucidate the organismal response to micro(nano)plastics at ERC from the perspective of in vivo toxic effects and mechanisms involved. This paper also puts forward some limitations of the current study and some suggestions for future research. Our study may be of great significance in further understanding the ecotoxicity of micro(nano)plastics.

Principles of Nanoparticle Delivery to Solid Tumors

The effective treatment of patients with cancer hinges on the delivery of therapeutics to a tumor site. Nanoparticles provide an essential transport system. We present 5 principles to consider when designing nanoparticles for cancer targeting: (a) Nanoparticles acquire biological identity in vivo, (b) organs compete for nanoparticles in circulation, (c) nanoparticles must enter solid tumors to target tumor components, (d) nanoparticles must navigate the tumor microenvironment for cellular or organelle targeting, and (e) size, shape, surface chemistry, and other physicochemical properties of nanoparticles influence their transport process to the target. This review article describes these principles and their application for engineering nanoparticle delivery systems to carry therapeutics to tumors or other disease targets.

Protein corona and exosomes: new challenges and prospects

Recent advances in extracellular vesicle (EVs) detection and isolation methods have led to the development of novel therapeutic modalities. Among different types of EVs, exosomes (Exos) can transfer different signaling biomolecules and exhibit several superior features compared to whole-cell-based therapies. Therapeutic factors are normally loaded into the Exo lumen or attached to their surface for improving the on-target delivery rate and regenerative outcomes. Despite these advantages, there are several limitations in the application of Exos in in vivo conditions. It was suggested that a set of proteins and other biological compounds are adsorbed around Exos in aqueous phases and constitute an external layer named protein corona (PC). Studies have shown that PC can affect the physicochemical properties of synthetic and natural nanoparticles (NPs) after introduction in biofluids. Likewise, PC is generated around EVs, especially Exos in in vivo conditions. This review article is a preliminary attempt to address the interfering effects of PC on Exo bioactivity and therapeutic effects. Video Abstract.

The protein corona from nanomedicine to environmental science

The protein corona spontaneously develops and evolves on the surface of nanoscale materials when they are exposed to biological environments, altering their physiochemical properties and affecting their subsequent interactions with biosystems. In this Review, we provide an overview of the current state of protein corona research in nanomedicine. We next discuss remaining challenges in the research methodology and characterization of the protein corona that slow the development of nanoparticle therapeutics and diagnostics, and we address how artificial intelligence can advance protein corona research as a complement to experimental research efforts. We then review emerging opportunities provided by the protein corona to address major issues in healthcare and environmental sciences. This Review details how mechanistic insights into nanoparticle protein corona formation can broadly address unmet clinical and environmental needs, as well as enhance the safety and efficacy of nanobiotechnology products.

Recent Progress in Proteins-Based Micelles as Drug Delivery Carriers

Proteins-derived polymeric micelles have gained attention and revolutionized the biomedical field. Proteins are considered a favorable choice for developing micelles because of their biocompatibility, harmlessness, greater blood circulation and solubilization of poorly soluble drugs. They exhibit great potential in drug delivery systems as capable of controlled loading, distribution and function of loaded agents to the targeted sites within the body. Protein micelles successfully cross biological barriers and can be incorporated into various formulation designs employed in biomedical applications. This review emphasizes the recent advances of protein-based polymeric micelles for drug delivery to targeted sites of various diseases. Most studied protein-based micelles such as soy, gelatin, casein and collagen are discussed in detail, and their applications are highlighted. Finally, the future perspectives and forthcoming challenges for protein-based polymeric micelles have been reviewed with anticipated further advances.

Single-Particle Functionality Imaging of Antibody-Conjugated Nanoparticles in Complex Media

The properties of nanoparticles (NPs) can change upon contact with serum components, occluding the NP surface by forming a biomolecular corona. It is believed that targeted NPs can lose their functionality due to this biological coating, thus losing specificity and selectivity toward target cells and leading to poor therapeutic efficiency. A better understanding of how the biomolecular corona affects NP ligand functionality is needed to maintain NP targeting capabilities. However, techniques that can quantify the functionality of NPs at a single-particle level in a complex medium are limited and often laborious in sample preparation, measurement, and analysis. In this work, the influence of serum exposure on the functionality of antibody-functionalized NPs was quantified using a straightforward total internal reflection fluorescence (TIRF) microscopy method and evaluated in cell uptake studies. The single-particle resolution of TIRF reveals the interparticle functionality heterogeneity and the substantial differences between NPs conjugated with covalent and noncovalent methods. Notably, only NPs covalently conjugated with a relatively high amount of antibodies maintain their functionality to a certain extent and still showed cell specificity and selectivity toward high receptor density cells after incubation in full serum. The presented study emphasizes the importance of single-particle functional characterization of NPs in complex media, contributing to the understanding and design of targeted NPs that retain their cell specificity and selectivity in biologically relevant conditions.

Cell surface biotinylation to identify the receptors involved in nanoparticle uptake into endothelial cells

Targeted drug delivery requires -among others- specific interaction of nanocarriers with cell surface receptors enabling efficient internalization into the targeted cells. Thus, identification of receptors allowing efficient nanocarrier uptake is essential to improve the design of targeted nanomedicines. Here we used methods based on cell surface biotinylation to identify cell surface receptors mediating nanoparticle uptake by cells. We used human brain and liver endothelial cells as representative examples of cells typically showing very low and very high nanoparticle uptake, respectively. Amino-modified and carboxylated silica were used as model nanoparticles usually associated with high and low uptake into cells, respectively, and carrying different coronas after exposure in full human plasma. Using cell surface biotinylation of live cells and receptor pull-down assays, we compared the receptors internalized in control untreated cells and those internalized upon exposure to nanoparticles. In this way, we identified receptors associated with (high) nanoparticle uptake. The candidate receptors were further validated by decorating the nanoparticles with an artificial corona consisting of the respective receptor ligands. We found that a vitronectin corona can be used to target integrin receptors and strongly enhances nanoparticle uptake in brain and liver endothelial cells. The increased uptake was maintained in the presence of serum, suggesting that the vitronectin-corona could resist interaction and competition with serum. Furthermore, plasminogen-coated nanoparticles promoted uptake in endothelial cells of the liver, but not of the brain. The presented approach using reversible biotinylation of cell surface receptors in live cells allows for receptor-based targeting of nanocarriers that are instrumental in nanoparticle uptake, which can be exploited for targeted drug delivery. STATEMENT OF SIGNIFICANCE: In order to deliver drugs to their site of action, drug-loaded nanocarriers can be targeted to cell receptors enabling efficient uptake into target cells. Thus, methods to identify nanocarrier receptors are invaluable. Here we used reversible biotinylation of live cells and receptor pull-down approaches for receptor identification. By comparative analysis of the individual receptors internalized in untreated cells and cells exposed to nanoparticles, we identified receptors enabling high nanoparticle uptake into liver and brain endothelial cells. Their role was confirmed by decorating nanoparticles with an artificial corona composed of the receptor ligands. In conclusion, live cell reversible biotinylation of cell surface proteins is a powerful tool for the identification of potential receptors for receptor-based targeting of nanocarriers.

The Impact of Nanobody Density on the Targeting Efficiency of PEGylated Liposomes

Nanoparticles (NPs) are commonly modified with tumor-targeting moieties that recognize proteins overexpressed on the extracellular membrane to increase their specific interaction with target cells. Nanobodies (Nbs), the variable domain of heavy chain-only antibodies, are a robust targeting ligand due to their small size, superior stability, and strong binding affinity. For the clinical translation of targeted Nb-NPs, it is essential to understand how the number of Nbs per NP impacts the receptor recognition on cells. To study this, Nbs targeting the hepatocyte growth factor receptor (MET-Nbs) were conjugated to PEGylated liposomes at a density from 20 to 800 per liposome and their targeting efficiency was evaluated in vitro. MET-targeted liposomes (MET-TLs) associated more profoundly with MET-expressing cells than non-targeted liposomes (NTLs). MET-TLs with approximately 150-300 Nbs per liposome exhibited the highest association and specificity towards MET-expressing cells and retained their targeting capacity when pre-incubated with proteins from different sources. Furthermore, a MET-Nb density above 300 Nbs per liposome increased the interaction of MET-TLs with phagocytic cells by 2-fold in ex vivo human blood compared to NTLs. Overall, this study demonstrates that adjusting the MET-Nb density can increase the specificity of NPs towards their intended cellular target and reduce NP interaction with phagocytic cells.

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.

Identifying cell receptors for the nanoparticle protein corona using genome screens

Nanotechnology provides platforms to deliver medical agents to specific cells. However, the nanoparticle's surface becomes covered with serum proteins in the blood after administration despite engineering efforts to protect it with targeting or blocking molecules. Here, we developed a strategy to identify the main interactions between nanoparticle-adsorbed proteins and a cell by integrating mass spectrometry with pooled genome screens and Search Tool for the Retrieval of Interacting Genes analysis. We found that the low-density lipoprotein (LDL) receptor was responsible for approximately 75% of serum-coated gold nanoparticle uptake in U-87 MG cells. Apolipoprotein B and complement C8 proteins on the nanoparticle mediated uptake through the LDL receptor. In vivo, nanoparticle accumulation correlated with LDL receptor expression in the organs of mice. A detailed understanding of how adsorbed serum proteins bind to cell receptors will lay the groundwork for controlling the delivery of nanoparticles at the molecular level to diseased tissues for therapeutic and diagnostic applications.

In vivo fate and intracellular trafficking of vaccine delivery systems

With the pandemic of severe acute respiratory syndrome coronavirus 2, vaccine delivery systems emerged as a core technology for global public health. Given that antigen processing takes place inside the cell, the intracellular delivery and trafficking of a vaccine antigen will contribute to vaccine efficiency. Investigations focusing on the in vivo behavior and intracellular transport of vaccines have improved our understanding of the mechanisms relevant to vaccine delivery systems and facilitated the design of novel potent vaccine platforms. In this review, we cover the intracellular trafficking and in vivo fate of vaccines administered via various routes and delivery systems. To improve immune responses, researchers have used various strategies to modulate vaccine platforms and intracellular trafficking. In addition to progress in vaccine trafficking studies, the challenges and future perspectives for designing next-generation vaccines are discussed.

Temperature, concentration, and surface modification influence the cellular uptake and the protein corona of polystyrene nanoparticles

The composition of the protein corona varies depending on several parameters and influences the cellular fate of the nanocarriers. Here, we investigated the influence of three key parameters (surface charge, temperature, and plasma concentration) on the formation and composition of the protein corona of polystyrene nanoparticles and ultimately on the cellular uptake of pre-coated nanoparticles. At a fixed temperature and concentration, the surface charge, and surfactant influence its composition. We observed that the composition of the corona formed at low temperatures (4°C) is different from that formed at physiological temperatures (37°C). At low plasma concentrations (up to 25%), the corona consists of more diverse proteins than at higher concentrations. Finally, we concluded that regardless of the nanoparticle formulation, the degree of uptake by model cancer and endothelial cells of the nanoparticles decreased when pre-coated at increasing temperature or plasma concentration. STATEMENT OF SIGNIFICANCE: Drug delivery through nanocarriers is an increasingly important concept in research and medicine. One problem in the application of nanocarriers in medicine is the protein corona that forms around the nanocarriers when they get in contact with protein-containing fluids. So far, several factors have been identified that influence the composition of the protein corona and thus the biological identity of the particles. However, lacking comparability remains between the studies because different concentrations or temperatures of the protein solutions are used. In this study we demonstrate how the incubation temperature or the concentration of plasma influences the protein corona and thus the cellular uptake of polystyrene nanoparticles.

Caveolin-initiated macropinocytosis is required for efficient silica nanoparticles' transcytosis across the alveolar epithelial barrier

Removal of particulate materials that would otherwise cumulate within the airspace and hinder the gas exchange is one of the central processes of maintaining lung homeostasis. While the importance of the particle uptake by alveolar macrophages and their expulsion via the airways mucociliary escalator is well established, very little is known about the alternative route for removing the particles via direct crossing the lung epithelium for transfer into the pulmonary lymph and bloodstream. This study dissected sequential mechanisms involved in nanoparticle transcytosis through the alveolar epithelial cell layer. By a combination of live cell, super resolution, and electron microscopy and RNA interference study, we have dissected temporal steps of nanoparticle transcytosis through alveolar epithelium. Our study revealed that caveolin is essential for the firm adhesion of the silica nanoparticle agglomerates to the apical membrane and their subsequent rapid internalization with the help of macropinocytic elements C-terminal-binding protein1 and Rabankyrin-5 but not dynamin. Actin, but not microtubules, played a major role in nanoparticle uptake and subsequent transportation. The compartments with nanoparticles were tethered to trans-Golgi network to be jointly transported along actin stress fibers across the cytoplasm, employing a myosin-dependent mechanism. The trans-Golgi nanoparticle transport machinery was positive to Rab6A, a marker linked to vesicle exocytosis. Exocytosis was primarily occurring at the basolateral plane of the alveolar epithelial cells. The high-proficiency novel caveolin and Rabankyrin-5 associated uptake and transcellular transport of nanoparticles across the AEC barrier supports its importance in clearance of amorphous silica and other types of non-inflammatory nanoparticles that are rapidly removed from the lungs following their inhalation.

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.

Chemical and Biophysical Signatures of the Protein Corona in Nanomedicine

An inconvenient hurdle in the practice of nanomedicine is the protein corona, a spontaneous collection of biomolecular species by nanoparticles in living systems. The protein corona is dynamic in composition and may entail improved water suspendability and compromised delivery and targeting to the nanoparticles. How much of this nonspecific protein ensemble is determined by the chemistry of the nanoparticle core and its surface functionalization, and how much of this entity is dictated by the biological environments that vary spatiotemporally in vivo? How do we "live with" and exploit the protein corona without significantly sacrificing the efficacy of nanomedicines in diagnosing and curing human diseases? This article discusses the chemical and biophysical signatures of the protein corona and ponders challenges ahead for the field of nanomedicine.

Mechanisms of Uptake and Membrane Curvature Generation for the Internalization of Silica Nanoparticles by Cells

Nanosized drug carriers enter cells via active mechanisms of endocytosis but the pathways involved are often not clarified. Cells possess several mechanisms to generate membrane curvature during uptake. However, the mechanisms of membrane curvature generation for nanoparticle uptake have not been explored so far. Here, we combined different methods to characterize how silica nanoparticles with a human serum corona enter cells. In these conditions, silica nanoparticles are internalized via the LDL receptor (LDLR). We demonstrate that despite the interaction with LDLR, uptake is not clathrin-mediated, as usually observed for this receptor. Additionally, silencing the expression of different proteins involved in clathrin-independent mechanisms and several BAR-domain proteins known to generate membrane curvature strongly reduces nanoparticle uptake. Thus, nanosized objects targeted to specific receptors, such as here LDLR, can enter cells via different mechanisms than their endogenous ligands. Additionally, nanoparticles may trigger alternative mechanisms of membrane curvature generation for their internalization.

Unique Properties of Surface-Functionalized Nanoparticles for Bio-Application: Functionalization Mechanisms and Importance in Application

This review tries to summarize the purpose of steadily developing surface-functionalized nanoparticles for various bio-applications and represents a fascinating and rapidly growing field of research. Due to their unique properties-such as novel optical, biodegradable, low-toxicity, biocompatibility, size, and highly catalytic features-these materials are considered superior, and it is thus vital to study these systems in a realistic and meaningful way. However, rapid aggregation, oxidation, and other problems are encountered with functionalized nanoparticles, inhibiting their subsequent utilization. Adequate surface modification of nanoparticles with organic and inorganic compounds results in improved physicochemical properties which can overcome these barriers. This review investigates and discusses the iron oxide nanoparticles, gold nanoparticles, platinum nanoparticles, silver nanoparticles, and silica-coated nanoparticles and how their unique properties after fabrication allow for their potential use in a wide range of bio-applications such as nano-based imaging, gene delivery, drug loading, and immunoassays. The different groups of nanoparticles and the advantages of surface functionalization and their applications are highlighted here. In recent years, surface-functionalized nanoparticles have become important materials for a broad range of bio-applications.

Nanoparticle and bioparticle deposition kinetics

Mechanisms and kinetic of particle deposition at solid surfaces leading to the formation of self-assembled layers of controlled structure and density were reviewed. In the first part theoretical aspects were briefly discussed, comprising limiting analytical solutions for the linear transport under flow and diffusion. Methods of the deposition kinetics analysis for non-linear regimes affected by surface blocking were also considered. Characteristic monolayer formation times under diffusion and flow for the nanoparticle size range were calculated. In the second part illustrative experimental results obtained for micro- and nanoparticles were discussed. Deposition at planar substrates was analyzed with emphasis focused on the stability of layers and the release kinetics of silver particles. Applicability of the quartz microbalance measurements (QCM) for quantitative studies of nanoparticle deposition kinetic was also discussed. Except for noble metal and polymer particles, representative results for virus deposition at abiotic surfaces were analyzed. Final part of the review was devoted to nanoparticle corona formation at polymer carrier particles investigated by combination of the concentration depletion, AFM, SEM and the in situ electrokinetic method. It is argued that the results obtained for colloid particles can be used as reliable reference systems for interpretation of protein and other bioparticle deposition, confirming the thesis that simple is universal.

Lipid Composition of the Cell Membrane Outer Leaflet Regulates Endocytosis of Nanomaterials through Alterations in Scavenger Receptor Activity

Understanding the principles that guide the uptake of engineered nanomaterials (ENMs) by cells is of interest in biomedical and occupational health research. While evidence has started to accumulate on the role of membrane proteins in ENM uptake, the role of membrane lipid chemistry in regulating ENM endocytosis has remained largely unexplored. Here, we have addressed this issue by altering the plasma membrane lipid composition directly in live cells using a methyl-α-cyclodextrin (MαCD)-catalyzed lipid exchange method. Our observations, in an alveolar epithelial cell line and using silica nanoparticles, reveal that the lipid composition of the plasma membrane outer leaflet plays a significant role in ENM endocytosis and the intracellular fate of ENMs, by affecting nonspecific ENM diffusion into the cell, changing membrane fluidity, and altering the activity of scavenger receptors (SRs) involved in active endocytosis. These results have implications for understanding ENM uptake in different subsets of cells, depending on cell membrane lipid composition.

Opsonin-Deficient Nucleoproteic Corona Endows UnPEGylated Liposomes with Stealth Properties In Vivo

For several decades, surface grafted polyethylene glycol (PEG) has been a go-to strategy for preserving the synthetic identity of liposomes in physiological milieu and preventing clearance by immune cells. However, the limited clinical translation of PEGylated liposomes is mainly due to the protein corona formation and the subsequent modification of liposomes' synthetic identity, which affects their interactions with immune cells and blood residency. Here we exploit the electric charge of DNA to generate unPEGylated liposome/DNA complexes that, upon exposure to human plasma, gets covered with an opsonin-deficient protein corona. The final product of the synthetic process is a biomimetic nanoparticle type covered by a proteonucleotidic corona, or "proteoDNAsome", which maintains its synthetic identity in vivo and is able to slip past the immune system more efficiently than PEGylated liposomes. Accumulation of proteoDNAsomes in the spleen and the liver was lower than that of PEGylated systems. Our work highlights the importance of generating stable biomolecular coronas in the development of stealth unPEGylated particles, thus providing a connection between the biological behavior of particles in vivo and their synthetic identity.

Designing Functional Bionanoconstructs for Effective In Vivo Targeting

The progress achieved over the last three decades in the field of bioconjugation has enabled the preparation of sophisticated nanomaterial–biomolecule conjugates, referred to herein as bionanoconstructs, for a multitude of applications including biosensing, diagnostics, and therapeutics. However, the development of bionanoconstructs for the active targeting of cells and cellular compartments, both in vitro and in vivo, is challenged by the lack of understanding of the mechanisms governing nanoscale recognition. In this review, we highlight fundamental obstacles in designing a successful bionanoconstruct, considering findings in the field of bionanointeractions. We argue that the biological recognition of bionanoconstructs is modulated not only by their molecular composition but also by the collective architecture presented upon their surface, and we discuss fundamental aspects of this surface architecture that are central to successful recognition, such as the mode of biomolecule conjugation and nanomaterial passivation. We also emphasize the need for thorough characterization of engineered bionanoconstructs and highlight the significance of population heterogeneity, which too presents a significant challenge in the interpretation of in vitro and in vivo results. Consideration of such issues together will better define the arena in which bioconjugation, in the future, will deliver functional and clinically relevant bionanoconstructs.

Revisiting the outstanding questions in cancer nanomedicine with a future outlook

The field of cancer nanomedicine has been fueled by the expectation of mitigating the inefficiencies and life-threatening side effects of conventional chemotherapy. Nanomedicine proposes to utilize the unique nanoscale properties of nanoparticles to address the most pressing questions in cancer treatment and diagnosis. The approval of nano-based products in the 1990s inspired scientific explorations in this direction. However, despite significant progress in the understanding of nanoscale properties, there are only very few success stories in terms of substantial increase in clinical efficacy and overall patient survival. All existing paradigms such as the concept of enhanced permeability and retention (EPR), the stealth effect and immunocompatibility of nanomedicine have been questioned in recent times. In this review we critically examine impediments posed by biological factors to the clinical success of nanomedicine. We put forth current observations on critical outstanding questions in nanomedicine. We also provide the promising side of cancer nanomedicine as we move forward in nanomedicine research. This would provide a future direction for research in nanomedicine and inspire ongoing investigations.

A Nanoscale Shape-Discovery Framework Supporting Systematic Investigations of Shape-Dependent Biological Effects and Immunomodulation

Since it is now possible to make, in a controlled fashion, an almost unlimited variety of nanostructure shapes, it is of increasing interest to understand the forms of biological control that nanoscale shape allows. However, a priori rational investigation of such a vast universe of shapes appears to present intractable fundamental and practical challenges. This has limited the useful systematic investigation of their biological interactions and the development of innovative nanoscale shape-dependent therapies. Here, we introduce a concept of biologically relevant inductive nanoscale shape discovery and evaluation that is ideally suited to, and will ultimately become, a vehicle for machine learning discovery. Combining the reproducibility and tunability of microfluidic flow nanochemistry syntheses, quantitative computational shape analysis, and iterative feedback from biological responses in vitro and in vivo, we show that these challenges can be mastered, allowing shape biology to be explored within accepted scientific and biomedical research paradigms. Early applications identify significant forms of shape-induced biological and adjuvant-like immunological control.

Nanophysical Mapping of Inflammasome Activation by Nanoparticles via Specific Cell Surface Recognition Events

Silica nanoparticles (SiNP) trigger a range of innate immune responses in relevant essential organs, such as the liver and the lungs. Inflammatory reactions, including NLRP3 inflammasome activation, have been linked to particulate materials; however, the molecular mechanisms and key actors remain elusive. Although many receptors, including several scavenger receptors, were suggested to participate in SiNP cellular uptake, mechanistic evidence of their role on innate immunity is lacking. Here we present an atomic force microscopy-based approach to physico-mechanically map the specific interaction occurring between nanoparticles and scavenger receptor A1 (SRA1) in vitro on living lung epithelial cells. We find that SiNP recognition by SRA1 on human macrophages plays a key role in mediating NLRP3 inflammasome activation, and we identify cellular mechanical changes as clear indicators of inflammasome activation in human macrophages, greatly advancing our knowledge on the interplay among nanomaterials and innate immunity.

Drug Targeting and Nanomedicine: Lessons Learned from Liver Targeting and Opportunities for Drug Innovation

Drug targeting and nanomedicine are different strategies for improving the delivery of drugs to their target. Several antibodies, immuno-drug conjugates and nanomedicines are already approved and used in clinics, demonstrating the potential of such approaches, including the recent examples of the DNA- and RNA-based vaccines against COVID-19 infections. Nevertheless, targeting remains a major challenge in drug delivery and different aspects of how these objects are processed at organism and cell level still remain unclear, hampering the further development of efficient targeted drugs. In this review, we compare properties and advantages of smaller targeted drug constructs on the one hand, and larger nanomedicines carrying higher drug payload on the other hand. With examples from ongoing research in our Department and experiences from drug delivery to liver fibrosis, we illustrate opportunities in drug targeting and nanomedicine and current challenges that the field needs to address in order to further improve their success.

On the mechanism of tissue-specific mRNA delivery by selective organ targeting nanoparticles

Lipid nanoparticles (LNPs) are a clinically mature technology for the delivery of genetic medicines but have limited therapeutic applications due to liver accumulation. Recently, our laboratory developed selective organ targeting (SORT) nanoparticles that expand the therapeutic applications of genetic medicines by enabling delivery of messenger RNA (mRNA) and gene editing systems to non-liver tissues. SORT nanoparticles include a supplemental SORT molecule whose chemical structure determines the LNP's tissue-specific activity. To understand how SORT nanoparticles surpass the delivery barrier of liver hepatocyte accumulation, we studied the mechanistic factors which define their organ-targeting properties. We discovered that the chemical nature of the added SORT molecule controlled biodistribution, global/apparent pK_a, and serum protein interactions of SORT nanoparticles. Additionally, we provide evidence for an endogenous targeting mechanism whereby organ targeting occurs via 1) desorption of poly(ethylene glycol) lipids from the LNP surface, 2) binding of distinct proteins to the nanoparticle surface because of recognition of exposed SORT molecules, and 3) subsequent interactions between surface-bound proteins and cognate receptors highly expressed in specific tissues. These findings establish a crucial link between the molecular composition of SORT nanoparticles and their unique and precise organ-targeting properties and suggest that the recruitment of specific proteins to a nanoparticle's surface can enable drug delivery beyond the liver.