A novel scavenging tool for cancer biomarker discovery based on the blood-circulating nanoparticle protein corona

Concepts and Approaches to Reduce or Avoid Protein Corona Formation on Nanoparticles: Challenges and Opportunities

This review describes the formation of a protein corona (or its absence) on different classes of nanoparticles, its basic principles, and its consequences for nanomedicine. For this purpose, it describes general concepts to control (guide/minimize) the interaction between artificial nanoparticles and plasma proteins to reduce protein corona formation. Thereafter, methods for the qualitative or quantitative determination of protein corona formation are presented, as well as the properties of nanoparticle surfaces, which are relevant for protein corona prevention (or formation). Thereby especially the role of grafting density of hydrophilic polymers on the surface of the nanoparticle is discussed to prevent the formation of a protein corona. In this context also the potential of detergents (surfactants) for a temporary modification as well as grafting-to and grafting-from approaches for a permanent modification of the surface are discussed. The review concludes by highlighting several promising avenues. This includes (i) the use of nanoparticles without protein corona for active targeting, (ii) the use of synthetic nanoparticles without protein corona formation to address the immune system, (iii) the recollection of nanoparticles with a defined protein corona after in vivo application to sample the blood proteome and (iv) further concepts to reduce protein corona formation.

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.

Deep Plasma Proteome Profiling by Modulating Single Nanoparticle Protein Corona with Small Molecules

The protein corona, a dynamic biomolecular layer that forms on nanoparticle (NP) surfaces upon exposure to biological fluids is emerging as a valuable diagnostic tool for improving plasma proteome coverage analyzed by liquid chromatography-mass spectrometry (LC-MS/MS). Here, we show that spiking small molecules, including metabolites, lipids, vitamins, and nutrients, into plasma can induce diverse protein corona patterns on otherwise identical NPs, significantly enhancing the depth of plasma proteome profiling. The protein coronas on polystyrene NPs when exposed to plasma treated with an array of small molecules (n=10) allowed for detection of 1793 proteins marking an 8.25-fold increase in the number of quantified proteins compared to plasma alone (218 proteins) and a 2.63-fold increase relative to the untreated protein corona (681 proteins). Furthermore, we discovered that adding 1000 μg/ml phosphatidylcholine could singularly increase the number of unique proteins within the protein corona (897 proteins). This specific concentration of phosphatidylcholine selectively depleted the four most abundant plasma proteins, including albumin, thus reducing concentration dynamic range of plasma proteome and boosting LC-MS/MS sensitivity for detection of proteins with lower abundance. By employing an optimized data-independent acquisition (DIA) approach, the inclusion of phosphatidylcholine led to the detection of 1436 proteins in plasma. This significant achievement is made utilizing only a single NP type and one small molecule to analyze a single plasma sample, setting a new standard in proteomic depth of the plasma sample. Given the critical role of plasma proteomics in biomarker discovery and disease monitoring, we anticipate widespread adoption of this methodology for identification and clinical translation of proteomic biomarkers into FDA approved diagnostics.

Protein Corona Sensor Array Nanosystem for Detection of Coronary Artery Disease

Coronary artery disease (CAD) is the most common type of heart disease and represents the leading cause of death in both men and women worldwide. Early detection of CAD is crucial for decreasing mortality, prolonging survival, and improving patient quality of life. Herein, a non-invasive is described, nanoparticle-based diagnostic technology which takes advantages of proteomic changes in the nano-bio interface for CAD detection. Nanoparticles (NPs) exposed to biological fluids adsorb on their surface a layer of proteins, the "protein corona" (PC). Pathological changes that alter the plasma proteome can directly result in changes in the PC. By forming disease-specific PCs on six NPs with varying physicochemical properties, a PC-based sensor array is developed for detection of CAD using specific PC pattern recognition. While the PC of a single NP may not provide the required specificity, it is reasoned that multivariate PCs across NPs with different surface chemistries, can provide the desirable information to selectively discriminate the condition under investigation. The results suggest that such an approach can detect CAD with an accuracy of 92.84%, a sensitivity of 87.5%, and a specificity of 82.5%. These new findings demonstrate the potential of PC-based sensor array detection systems for clinical use.

A uniform data processing pipeline enables harmonized nanoparticle protein corona analysis across proteomics core facilities

Protein corona, a layer of biomolecules primarily comprising proteins, forms dynamically on nanoparticles in biological fluids and is crucial for predicting nanomedicine safety and efficacy. The protein composition of the corona layer is typically analyzed using liquid chromatography-mass spectrometry (LC-MS/MS). Our recent study, involving identical samples analyzed by 17 proteomics facilities, highlighted significant data variability, with only 1.8% of proteins consistently identified across these centers. Here, we implement an aggregated database search unifying parameters such as variable modifications, enzyme specificity, number of allowed missed cleavages and a stringent 1% false discovery rate at the protein and peptide levels. Such uniform search dramatically harmonizes the proteomics data, increasing the reproducibility and the percentage of consistency-identified unique proteins across distinct cores. Specifically, out of the 717 quantified proteins, 253 (35.3%) are shared among the top 5 facilities (and 16.2% among top 11 facilities). Furthermore, we note that reduction and alkylation are important steps in protein corona sample processing and as expected, omitting these steps reduces the number of total quantified peptides by around 20%. These findings underscore the need for standardized procedures in protein corona analysis, which is vital for advancing clinical applications of nanoscale biotechnologies.

Disease-specific protein corona formed in pathological intestine enhances the oral absorption of nanoparticles

Protein corona (PC) has been identified to impede the transportation of intravenously injected nanoparticles (NPs) from blood circulation to their targeted sites. However, how intestinal PC (IPC) affects the delivery of orally administered NPs are still needed to be elucidated. Here, we found that IPC exerted "positive effect" or "negative effect" depending on different pathological conditions in the gastrointestinal tract. We prepared polystyrene nanoparticles (PS) adsorbed with different IPC derived from the intestinal tract of healthy, diabetic, and colitis rats (H-IPC@PS, D-IPC@PS, C-IPC@PS). Proteomics analysis revealed that, compared with healthy IPC, the two disease-specific IPC consisted of a higher proportion of proteins that were closely correlated with transepithelial transport across the intestine. Consequently, both D-IPC@PS and C-IPC@PS mainly exploited the recycling endosome and ER-Golgi mediated secretory routes for intracellular trafficking, which increased the transcytosis from the epithelium. Together, disease-specific IPC endowed NPs with higher intestinal absorption. D-IPC@PS posed "positive effect" on intestinal absorption into blood circulation for diabetic therapy. Conversely, C-IPC@PS had "negative effect" on colitis treatment because of unfavorable absorption in the intestine before arriving colon. These results imply that different or even opposite strategies to modulate the disease-specific IPC need to be adopted for oral nanomedicine in the treatment of variable diseases.

The influence of protein corona on Graphene Oxide: implications for biomedical theranostics

Graphene-based nanomaterials have attracted significant attention in the field of nanomedicine due to their unique atomic arrangement which allows for manifold applications. However, their inherent high hydrophobicity poses challenges in biological systems, thereby limiting their usage in biomedical areas. To address this limitation, one approach involves introducing oxygen functional groups on graphene surfaces, resulting in the formation of graphene oxide (GO). This modification enables improved dispersion, enhanced stability, reduced toxicity, and tunable surface properties. In this review, we aim to explore the interactions between GO and the biological fluids in the context of theranostics, shedding light on the formation of the "protein corona" (PC) i.e., the protein-enriched layer that formed around nanosystems when exposed to blood. The presence of the PC alters the surface properties and biological identity of GO, thus influencing its behavior and performance in various applications. By investigating this phenomenon, we gain insights into the bio-nano interactions that occur and their biological implications for different intents such as nucleic acid and drug delivery, active cell targeting, and modulation of cell signalling pathways. Additionally, we discuss diagnostic applications utilizing biocoronated GO and personalized PC analysis, with a particular focus on the detection of cancer biomarkers. By exploring these cutting-edge advancements, this comprehensive review provides valuable insights into the rapidly evolving field of GO-based nanomedicine for theranostic applications.

Comprehensive and deep profiling of the plasma proteome with protein corona on zeolite NaY

Proteomic characterization of plasma is critical for the development of novel pharmacodynamic biomarkers. However, the vast dynamic range renders the profiling of proteomes extremely challenging. Here, we synthesized zeolite NaY and developed a simple and rapid method to achieve comprehensive and deep profiling of the plasma proteome using the plasma protein corona formed on zeolite NaY. Specifically, zeolite NaY and plasma were co-incubated to form plasma protein corona on zeolite NaY (NaY-PPC), followed by conventional protein identification using liquid chromatography-tandem mass spectrometry. NaY was able to significantly enhance the detection of low-abundance plasma proteins, minimizing the "masking" effect caused by high-abundance proteins. The relative abundance of middle- and low-abundance proteins increased substantially from 2.54% to 54.41%, and the top 20 high-abundance proteins decreased from 83.63% to 25.77%. Notably, our method can quantify approximately 4000 plasma proteins with sensitivity up to pg/mL, compared to only about 600 proteins identified from untreated plasma samples. A pilot study based on plasma samples from 30 lung adenocarcinoma patients and 15 healthy subjects demonstrated that our method could successfully distinguish between healthy and disease states. In summary, this work provides an advantageous tool for the exploration of plasma proteomics and its translational applications.

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.

Self-Therapeutic Nanomaterials: Applications in Biology and Medicine

Over past decades, nanotechnology has contributed to the biomedical field in areas including detection, diagnosis, and drug delivery via opto-electronic properties or enhancement of biological effects. Though generally considered inert delivery vehicles, a plethora of past and present evidence demonstrates that nanomaterials also exude unique intrinsic biological activity based on composition, shape, and surface functionalization. These intrinsic biological activities, termed self-therapeutic properties, take several forms, including mediation of cell-cell interactions, modulation of interactions between biomolecules, catalytic amplification of biochemical reactions, and alteration of biological signal transduction events. Moreover, study of biomolecule-nanomaterial interactions offers a promising avenue for uncovering the molecular mechanisms of biology and the evolution of disease. In this review, we observe the historical development, synthesis, and characterization of self-therapeutic nanomaterials. Next, we discuss nanomaterial interactions with biological systems, starting with administration and concluding with elimination. Finally, we apply this materials perspective to advances in intrinsic nanotherapies across the biomedical field, from cancer therapy to treatment of microbial infections and tissue regeneration. We conclude with a description of self-therapeutic nanomaterials in clinical trials and share our perspective on the direction of the field in upcoming years.

Synthesis of Surface-Functionalized Molybdenum Disulfide Nanomaterials for Efficient Adsorption and Deep Profiling of the Human Plasma Proteome by Data-Independent Acquisition

Blood is one of the most important clinical samples for protein biomarker discovery, as it provides rich physiological and pathological information and is easy to obtain with low invasiveness. However, the discovery of protein biomarkers in the blood by mass spectrometry (MS)-based proteomic strategies has been shown to be highly challenging due to the particularly large concentration range of proteins and the strong interference by the high-abundant proteins in the blood. Therefore, developing sensitive methods for low-abundant biomarker protein identification is a key issue that has received great attention. Here, we report the synthesis and characterization of surface-functionalized magnetic molybdenum disulfide (MoS₂) for the large-scale adsorption of low-abundant plasma proteins and deep profiling by MS. MoS₂ nanomaterials resulted in the coverage of more than 3400 proteins (including a single-peptide hit) in a single LC-MS analysis without peptide prefractionation using pooled plasma samples, which were five times more than those obtained by the direct analysis of the plasma proteome. A detection limit in the low ng L^-1 range was obtained, which is rare compared with previous reports.

Nanotechnology Meets Oncology: A Perspective on the Role of the Personalized Nanoparticle-Protein Corona in the Development of Technologies for Pancreatic Cancer Detection

In recent years nanotechnology has opened exciting opportunities in the struggle against cancer. In 2007 Dawson and coworkers demonstrated that nanomaterials exposed to biological fluids are coated with plasma proteins that form the so-called “protein corona”. A few years later our joint research team made of physicists, chemists, biotechnologists, surgeons, oncologists, and bioinformaticians introduced the concept of “personalized protein corona” and demonstrated that it is unique for each human condition. This concept paved the way for the development of nano-enabled blood (NEB) tests for the diagnosis of pancreatic ductal adenocarcinoma (PDAC). These studies gave an impetus to serious work in the field that came to maturity in the late 2010s. In this special issue, we provide the reader with a comprehensive overview of the most significant discoveries of our research team in the field of PDAC detection. We focus on the main achievements with an emphasis on the fundamental aspects of this arena and how they shaped the integration of different scientific backgrounds towards the development of advanced diagnostic technologies. We conclude the review by outlining future perspectives and opportunities to transform the NEB tests into a reliable clinical diagnostic technology for early diagnosis, follow-up, and management of PDAC patients.

Nano-omics: nanotechnology-based multidimensional harvesting of the blood-circulating cancerome

Over the past decade, the development of 'simple' blood tests that enable cancer screening, diagnosis or monitoring and facilitate the design of personalized therapies without the need for invasive tumour biopsy sampling has been a core ambition in cancer research. Data emerging from ongoing biomarker development efforts indicate that multiple markers, used individually or as part of a multimodal panel, are required to enhance the sensitivity and specificity of assays for early stage cancer detection. The discovery of cancer-associated molecular alterations that are reflected in blood at multiple dimensions (genome, epigenome, transcriptome, proteome and metabolome) and integration of the resultant multi-omics data have the potential to uncover novel biomarkers as well as to further elucidate the underlying molecular pathways. Herein, we review key advances in multi-omics liquid biopsy approaches and introduce the 'nano-omics' paradigm: the development and utilization of nanotechnology tools for the enrichment and subsequent omics analysis of the blood-circulating cancerome.

Squaric Ester-Based Nanogels Induce No Distinct Protein Corona but Entrap Plasma Proteins into their Porous Hydrogel Network

After intravenous administration of nanocarriers, plasma proteins may rapidly adsorb onto their surfaces. This process hampers the prediction of the nanocarriers' pharmacokinetics as it determines their physiological identity in a complex biological environment. Toward clinical translation it is therefore an essential prerequisite to investigate the nanocarriers' interaction with plasma proteins. Here, this work evaluates a highly "PEGylated" squaric ester-based nanogel with inherent prolonged blood circulation properties. After incubation with human blood plasma, the nanogels are isolated by asymmetrical flow-field flow fractionation. Multiangle light scattering measurements confirm the absence of significant size increases as well as aggregation upon plasma incubation. However, proteomic analyses by gel electrophoresis find minor absolute amounts of proteins (3 wt%), whereas label-free liquid chromatography mass spectrometry identify 65 enriched proteins. Interestingly, the relative abundance of these proteins is almost similar to their proportion in pure native plasma. Due to the nanogels' hydrated and porous network morphology, it is concluded that the detected proteins rather result from passive diffusion into the nanogel network than from specific interactions at the plasma particle interface. Consequently, these results do not indicate a classical surface protein corona but rather reflect the highly outer and inner stealth-like behavior of the porous hydrogel network.

Identification of the target protein of the metastatic colorectal cancer-specific aptamer W3 as a biomarker by aptamer-based target cells sorting and functional characterization

Metastasis is a leading cause of cancer-related deaths. Hence, the discovery of more reliable metastasis-related biomarkers is crucial to improve the survival rate of cancer patients. W3 is an aptamer previously produced by the subtractive cell-SELEX using metastatic colorectal cancer cells as target cells and non-metastatic cells as negative cells. In this study, we aimed to evaluate whether the target molecule of W3 can potentially act as a metastatic biomarker. First, we obtained two cell subpopulations with different expression levels of the target molecule by W3-based cell sorting. Subsequently, we demonstrated that W3^high cells have a higher metastatic potential than W3^low cells both in vitro and in vivo. Further, immunohistochemical analysis revealed that W3 target expression is positively associated with metastasis and poor prognosis of CRC patients. Using mass spectrometry (MS) combined with pull-down, we identified that Ephrin type-A receptor 2 (EphA2) is the target of W3. EphA2's potential as a metastatic predictor was demonstrated by capturing W3-positive circulating tumor cells from CRC patients using a W3 probe. Based on these results, we put forward a stratagem for cell-SELEX-based biomarker discovery: selecting an aptamer through subtractive cell-SELEX towards the phenotype of interest; evaluating the functional phenotype of the target molecule by aptamer-based target cell sorting and analysis of clinical samples; and identifying the aptamer's target molecule using MS and aptamer-based target enrichment. This stratagem not only shortens the time for the clinical application of aptamers but also enables a more targeted and efficient discovery of biomarkers.

Nanoparticle personalized biomolecular corona: implications of pre-existing conditions for immunomodulation and cancer

Nanoparticles (NPs) have demonstrated great promise as immunotherapies for applications ranging from cancer, autoimmunity, and infectious disease. Upon encountering biological fluids, NPs rapidly adsorb biomolecules, forming the "biomolecular corona" (BC), and the altered character of NPs due to their newly acquired biological identity can impact their in vivo fate. Recently, it has been shown that the NP-BC is person-specific, and even minute differences in the biomolecule composition can give rise to altered immune recognition, cellular interactions, pharmacokinetics, and biodistribution. Given the current rise in the development of NP-based therapeutics, it is of utmost importance to better understand how pre-existing conditions, that result in the formation of a personalized BC, can be leveraged to aid in the prediction of the therapeutic outcomes of NPs. In this minireview, we will discuss the formation of the BC, implications of the BC for NP-biological interactions, and its clinical importance in the context of immunomodulation and cancer therapeutics.

Nanotechnology Tools Enabling Biological Discovery

Over the years, the engineering aspect of nanotechnology has been significantly exploited. Medical intervention strategies have been developed by leveraging existing molecular biology knowledge and combining it with nanotechnology tools to improve outcomes. However, little attention has been paid to harnessing the strengths of nanotechnology as a biological discovery tool. Fundamental understanding of controlling dynamic biological processes at the subcellular level is key to developing personalized therapeutic and diagnostic interventions. Single-cell analyses using intravital microscopy, expansion microscopy, and microfluidic-based platforms have been helping to better understand cell heterogeneity in healthy and diseased cells, a major challenge in oncology. Also, single-cell analysis has revealed critical signaling pathways and biological intracellular components with key biological functions. The physical manipulation enabled by nanotools can allow real-time monitoring of biological changes at a single-cell level by sampling intracellular fluid from the same cell. The formation of intercellular highways by nanotube-like structures has important clinical implications such as metastasis development. The integration of nanomaterials into optical and molecular imaging techniques has rendered valuable morphological, structural, and biological information. Nanoscale imaging unravels mechanisms of temporality by enabling the visualization of nanoscale dynamics never observed or measured between individual cells with standard biological techniques. The exceptional sensitivity of nanozymes, artificial enzymes, make them perfect components of the next-generation mobile diagnostics devices. Here, we highlight these impactful cancer-related biological discoveries enabled by nanotechnology and producing a paradigm shift in cancer research and oncology.

The effect of drug loading and multiple administration on the protein corona formation and brain delivery property of PEG-PLA nanoparticles

The presence of protein corona on the surface of nanoparticles modulates their physiological interactions such as cellular association and targeting property. It has been shown that α-mangostin (αM)-loaded poly(ethylene glycol)-poly(l-lactide) (PEG-PLA) nanoparticles (NP-αM) specifically increased low density lipoprotein receptor (LDLR) expression in microglia and improved clearance of amyloid beta (Aβ) after multiple administration. However, how do the nanoparticles cross the blood‒brain barrier and access microglia remain unknown. Here, we studied the brain delivery property of PEG-PLA nanoparticles under different conditions, finding that the nanoparticles exhibited higher brain transport efficiency and microglia uptake efficiency after αM loading and multiple administration. To reveal the mechanism, we performed proteomic analysis to characterize the composition of protein corona formed under various conditions, finding that both drug loading and multiple dosing affect the composition of protein corona and subsequently influence the cellular uptake of nanoparticles in b.End3 and BV-2 cells. Complement proteins, immunoglobulins, RAB5A and CD36 were found to be enriched in the corona and associated with the process of nanoparticles uptake. Collectively, we bring a mechanistic understanding about the modulator role of protein corona on targeted drug delivery, and provide theoretical basis for engineering brain or microglia-specific targeted delivery system.

Current hurdles to the translation of nanomedicines from bench to the clinic

The field of nanomedicine has significantly influenced research areas such as drug delivery, diagnostics, theranostics, and regenerative medicine; however, the further development of this field will face significant challenges at the regulatory level if related guidance remains unclear and unconsolidated. This review describes those features and pathways crucial to the clinical translation of nanomedicine and highlights considerations for early-stage product development. These include identifying those critical quality attributes of the drug product essential for activity and safety, appropriate analytical methods (physical, chemical, biological) for characterization, important process parameters, and adequate pre-clinical models. Additional concerns include the evaluation of batch-to-batch consistency and considerations regarding scaling up that will ensure a successful reproducible manufacturing process. Furthermore, we advise close collaboration with regulatory agencies from the early stages of development to assure an aligned position to accelerate the development of future nanomedicines.

Physiology, pathology and the biomolecular corona: the confounding factors in nanomedicine design

The biomolecular corona that forms on nanomedicines in different physiological and pathological environments confers a new biological identity. How the recipient biological system's state can potentially affect nanomedicine corona formation, and how this can be modulated, remains obscure. With this perspective, this review summarizes the current knowledge about the content of biological fluids in various compartments and how they can be affected by pathological states, thus impacting biomolecular corona formation. The content of representative biological fluids is explored, and the urgency of integrating corona formation, as an essential component of nanomedicine designs for effective cargo delivery, is highlighted.

The impact of protein corona on the biological behavior of targeting nanomedicines

For successful translation of targeting nanomedicines from bench to bedside, it is vital to address their most common drawbacks namely rapid clearance and off-target accumulation. These complications evidently originate from a phenomenon called "protein corona (PC) formation" around the surface of targeting nanoparticles (NPs) which happens once they encounter the bloodstream and interact with plasma proteins with high collision frequency. This phenomenon endows the targeting nanomedicines with a different biological behavior followed by an unexpected fate, which is usually very different from what we commonly observe in vitro. In addition to the inherent physiochemical properties of NPs, the targeting ligands could also remarkably dictate the amount and type of adsorbed PC. As very limited studies have focused their attention on this particular factor, the present review is tasked to discuss the best simulated environment and latest characterization techniques applied to PC analysis. The effect of PC on the biological behavior of targeting NPs engineered with different targeting moieties is further discussed. Ultimately, the recent progresses in manipulation of nano-bio interfaces to achieve the most favorite therapeutic outcome are highlighted.

The nanotopography of SiO2 particles impacts the selectivity and 3D fold of bound allergens

A detailed description of the changes that occur during the formation of protein corona represents a fundamental question in nanoscience, given that it not only impacts the behaviour of nanoparticles but also affects the bound proteins. Relevant questions include whether proteins selectively bind particles, whether a specific orientation is preferred for binding, and whether particle binding leads to a modulation of their 3D fold. For allergens, it is important to answer these questions given that all these effects can modify the allergenic response of atopic individuals. These potential impacts on the bound allergen are closely related to the specific properties of the involved nanoparticles. One important property influencing the formation of protein corona is the nanotopography of the particles. Herein, we studied the effect of nanoparticle porosity on allergen binding using mesoporous and non-porous SiO₂ NPs. We investigated (i) the selectivity of allergen binding from a mixture such as crude pollen extract, (ii) whether allergen binding results in a preferred orientation, (iii) the influence of binding on the conformation of the allergen, and (iv) how the binding affects the allergenic response. Nanotopography was found to play a major role in the formation of protein corona, impacting the physicochemical and biological properties of the NP-bound allergen. The porosity of the surface of the SiO₂ nanoparticles resulted in a higher binding capacity with pronounced selectivity for (preferentially) binding the major birch pollen allergen Bet v 1. Furthermore, the binding of Bet v 1 to the mesoporous rather than the non-porous SiO₂ nanoparticles influenced the 3D fold of the protein, resulting in at least partial unfolding. Consequently, this conformational change influenced the allergenic response, as observed by mediator release assays employing the sera of patients and immune effector cells. For an in-depth understanding of the bio-nano interactions, the properties of the particles need to be considered not only regarding the identity and morphology of the material, but also their nanotopography, given that porosity may greatly influence the structure, and hence the biological behaviour of the bound proteins. Thus, thorough structural investigations upon the formation of protein corona are important when considering immunological outcomes, as particle binding can influence the allergenic response elicited by the bound allergen.

Unraveling the Effect of Breast Cancer Patients' Plasma on the Targeting Ability of Folic Acid-Modified Chitosan Nanoparticles

The formation of protein corona (PC) around nanoparticles (NPs) has been reported inside biological conditions. This effect can alter delivery capacity toward the targeted tissues. Here, we synthesized folic acid-modified chitosan NPs (FA-CS NPs) using different concentrations of folic acid (5, 10, and 20%). FA-CS NPs were exposed to plasmas of breast cancer patients and healthy donors to evaluate the possibility of PC formation. We also monitored uptake efficiency in in vitro conditions after incubation with human breast cancer cell line MDA-MB-231 and monocyte/macrophage-like Raw264.7 cells. Data showed that the formation of PC around FA-CS NPs can change physicochemical properties coincided with the rise in NP size and negative surface charge. SDS-PAGE electrophoresis revealed differences in the type and content rate of plasma proteins attached to NP surface in a personalized manner. Based on MTT data, the formation of PC around NPs did not exert cytotoxic effects on MDA-MB-231 cells while this phenomenon reduced uptake rate. Fluorescence imaging and flow cytometry analyses revealed reduced cellular internalization rate in NPs exposed to patients' plasma compared to the control group. In contrast to breast MDA-MB-231 cells, Raw264.7 cells efficiently adsorbed the bare and PC-coated NPs from both sources, indicating the involvement of ligand-receptor-dependent and independent cellular engulfment. These data showed that the PC formed on the FA-CS NPs is entirely different in breast cancer patients and healthy counterparts. PC derived from patients' plasma almost abolishes the targeting efficiency of FA-CS NPs even in different mechanisms, while this behavior was not shown in the control group. Surprisingly, Raw264.7 cells strongly adsorbed the PC-coated NPs, especially when these particles were in the presence of patients' sera. It is strongly suggested that the formation of PC around can affect delivering capacity of FA-CS NPs to cancer cells. It seems that the PC-coated FA-CS NPs can be used as an efficient delivery strategy for the transfer of specific biomolecules in immune system disorders.

Toward the Specificity of Bare Nanomaterial Surfaces for Protein Corona Formation

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

The protein corona and its effects on nanoparticle-based drug delivery systems

In most cases, once nanoparticles (NPs) enter the blood, their surface is covered by biological molecules, especially proteins, forming a so-called protein corona (PC). As a result, what the cells of the body "see" is not the NPs as formulated by the chemists, but the PC. In this way, the PC can influence the effects of the NPs and even mask the desired effects of the NP components. While this can argue for trying to inhibit protein-nanomaterial interactions, encapsulating NPs in an endogenous PC may increase their clinical usefulness. In this review, we briefly introduce the concept of the PC, its formation and its effects on the behavior of NPs. We also discuss how to reduce the formation of PCs or exploit them to enhance NP functions. Studying the interactions between proteins and NPs will provide insights into their clinical activity in health and disease. STATEMENT OF SIGNIFICANCE: The formation of protein corona (PC) will affect the operation of nanoparticles (NPs) in vivo. Since there are many proteins in the blood, it is impossible to completely overcome the formation of PC. Therefore, the use of PCs to deliver drug is the best choice. De-opsonins adsorbed on NPs can reduce macrophage phagocytosis and cytotoxicity of NPs, and prolong their circulation in blood. Albumin, apolipoprotein and transferrin are typical de-opsonins. In present review, we mainly discuss how to optimize the delivery of nanoparticles through the formation of albumin corona, transferrin corona and apolipoprotein corona in vivo or in vitro.

Optimal centrifugal isolating of liposome-protein complexes from human plasma

In the past few years, characterization of the protein corona (PC) that forms around liposomal systems has gained increasing interest for the development of novel therapeutic and diagnostic technologies. At the crossroads of fast-moving research fields, the interdisciplinarity of protein corona investigations poses challenges for experimental design and reporting. Isolation of liposome-protein complexes from biological fluids has been identified as a fundamental step of the entire workflow of PC characterization but exact specifications for conditions to optimize pelleting remain elusive. In the present work, key factors affecting precipitation of liposome-protein complexes by centrifugation, including time of centrifugation, total sample volume, lipid : protein ratio and contamination from biological NPs were comprehensively evaluated. Here we show that the total amount of isolated liposome-protein complexes and the extent of contamination from biological NPs may vary with influence factors. Our results provide protein corona researchers with precise indications to separate liposome-protein complexes from protein-rich fluids and include proper controls, thus they are anticipated to catalyze improved consistency of data mining and computational modelling of protein corona composition.

Sex as an important factor in nanomedicine

Nanomedicine has demonstrated substantial potential to improve the quality and efficacy of healthcare systems. Although the promise of nanomedicine to transform conventional medicine is evident, significant numbers of therapeutic nanomedicine products have failed in clinical trials. Most studies in nanomedicine have overlooked several important factors, including the significance of sex differences at various physiological levels. This report attempts to highlight the importance of sex in nanomedicine at cellular and molecular level. A more thorough consideration of sex physiology, among other critical variations (e.g., health status of individuals), would enable researchers to design and develop safer and more-efficient sex-specific diagnostic and therapeutic nanomedicine products.

Nanoparticle-Enabled Enrichment of Longitudinal Blood Proteomic Fingerprints in Alzheimer's Disease

Blood-circulating biomarkers have the potential to detect Alzheimer's disease (AD) pathology before clinical symptoms emerge and to improve the outcomes of clinical trials for disease-modifying therapies. Despite recent advances in understanding concomitant systemic abnormalities, there are currently no validated or clinically used blood-based biomarkers for AD. The extremely low concentration of neurodegeneration-associated proteins in blood necessitates the development of analytical platforms to address the "signal-to-noise" issue and to allow an in-depth analysis of the plasma proteome. Here, we aimed to discover and longitudinally track alterations of the blood proteome in a transgenic mouse model of AD, using a nanoparticle-based proteomics enrichment approach. We employed blood-circulating, lipid-based nanoparticles to extract, analyze and monitor AD-specific protein signatures and to systemically uncover molecular pathways associated with AD progression. Our data revealed the existence of multiple proteomic signals in blood, indicative of the asymptomatic stages of AD. Comprehensive analysis of the nanoparticle-recovered blood proteome by label-free liquid chromatography-tandem mass spectrometry resulted in the discovery of AD-monitoring signatures that could discriminate the asymptomatic phase from amyloidopathy and cognitive deterioration. While the majority of differentially abundant plasma proteins were found to be upregulated at the initial asymptomatic stages, the abundance of these molecules was significantly reduced as a result of amyloidosis, suggesting a disease-stage-dependent fluctuation of the AD-specific blood proteome. The potential use of the proposed nano-omics approach to uncover information in the blood that is directly associated with brain neurodegeneration was further exemplified by the recovery of focal adhesion cascade proteins. We herein propose the integration of nanotechnology with already existing proteomic analytical tools in order to enrich the identification of blood-circulating signals of neurodegeneration, reinvigorating the potential clinical utility of the blood proteome at predicting the onset and kinetics of the AD progression trajectory.

Hard and Soft Protein Corona of Nanomaterials: Analysis and Relevance

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

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

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

Emerging Biomolecular Testing to Assess the Risk of Mortality from COVID-19 Infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 and COVID-19) has produced an unprecedented global pandemic. Though the death rate from COVID-19 infection is ∼2%, many infected people recover at home. Among patients for whom COVID-19 is deadly are those with pre-existing comorbidities. Therefore, identification of populations at highest risk of COVID-19 mortality could significantly improve the capacity of healthcare providers to take early action and minimize the possibility of overwhelming care centers, which in turn would save many lives. Although several approaches have been used/developed (or are being developed/suggested) to diagnose COVID-19 infection, no approach is available/proposed for fast diagnosis of COVID-19 infections likely to be fatal. The central aim of this short perspective is to suggest a few possible nanobased technologies (i.e., protein corona sensor array and magnetic levitation) that could discriminate COVID-19-infected people while still in the early stages of infection who are at high risk of death. Such discrimination technologies would not only be useful in protecting health care centers from becoming overwhelmed but would also provide a powerful tool to better control possible future pandemics with a less social and economic burden.

Nanotools for Sepsis Diagnosis and Treatment

Sepsis is one of the leading causes of death worldwide with high mortality rates and a pathological complexity hindering early and accurate diagnosis. Today, laboratory culture tests are the epitome of pathogen recognition in sepsis. However, their consistency remains an issue of controversy with false negative results often observed. Clinically used blood markers, C reactive protein (CRP) and procalcitonin (PCT) are indicators of an acute-phase response and thus lack specificity, offering limited diagnostic efficacy. In addition to poor diagnosis, inefficient drug delivery and the increasing prevalence of antibiotic-resistant microorganisms constitute significant barriers in antibiotic stewardship and impede effective therapy. These challenges have prompted the exploration for alternative strategies that pursue accurate diagnosis and effective treatment. Nanomaterials are examined for both diagnostic and therapeutic purposes in sepsis. The nanoparticle (NP)-enabled capture of sepsis causative agents and/or sepsis biomarkers in biofluids can revolutionize sepsis diagnosis. From the therapeutic point of view, currently existing nanoscale drug delivery systems have proven to be excellent allies in targeted therapy, while many other nanotherapeutic applications are envisioned. Herein, the most relevant applications of nanomedicine for the diagnosis, prognosis, and treatment of sepsis is reviewed, providing a critical assessment of their potentiality for clinical translation.

Boosting nanotoxicity to combat multidrug-resistant bacteria in pathophysiological environments

Nanomaterials are promising novel antibiotics, but often ineffective. We found that nanomaterial-bacteria complex formation occurred with various nanomaterials. The bactericidal activity of NMs strongly depends on their physical binding to (multidrug-resistant) bacteria. Nanomaterials' binding and antibiotic effect was reduced by various pathophysiological biomolecule coronas strongly inhibiting their antibiotic effects. We show from analytical to in vitro to in vivo that nanomaterial-based killing could be restored by acidic pH treatments. Here, complex formation of negatively-charged, plasma corona-covered, nanomaterials with bacteria was electrostatically enhanced by reducing bacteria's negative surface charge. Employing in vivo skin infection models, acidic pH-induced complex formation was critical to counteract Staphylococcus aureus infections by silver nanomaterials. We explain why nano-antibiotics show reduced activity and provide a clinically practical solution.

COVID-19: Nanomedicine Uncovers Blood-Clot Mystery

Further complications associated with infection by severe acute respiratory syndrome coronavirus 2 (a.k.a. SARS-CoV-2) continue to be reported. Very recent findings reveal that 20-30% of patients at high risk of mortality from COVID-19 infection experience blood clotting that leads to stroke and sudden death. Timely assessment of the severity of blood clotting will be of enormous help to clinicians in determining the right blood-thinning medications to prevent stroke or other life-threatening consequences. Therefore, rapid identification of blood-clotting-related proteins in the plasma of COVID-19 patients would save many lives. Several nanotechnology-based approaches are being developed to diagnose patients at high risk of death due to complications from COVID-19 infections, including blood clots. This Perspective outlines (i) the significant potential of nanomedicine in assessing the risk of blood clotting and its severity in SARS-CoV-2 infected patients and (ii) its synergistic roles with advanced mass-spectrometry-based proteomics approaches in identifying the important protein patterns that are involved in the occurrence and progression of this disease. The combination of such powerful tools might help us understand the clotting phenomenon and pave the way for development of new diagnostics and therapeutics in the fight against COVID-19.

The biomolecule corona of lipid nanoparticles contains circulating cell-free DNA

The spontaneous adsorption of biomolecules onto the surface of nanoparticles (NPs) in complex physiological biofluids has been widely investigated over the last decade. Characterisation of the protein composition of the 'biomolecule corona' has dominated research efforts, whereas other classes of biomolecules, such as nucleic acids, have received no interest. Scarce, speculative statements exist in the literature about the presence of nucleic acids in the biomolecule corona, with no previous studies attempting to describe the contribution of genomic content to the blood-derived NP corona. Herein, we provide the first experimental evidence of the interaction of circulating cell-free DNA (cfDNA) with lipid-based NPs upon their incubation with human plasma samples, obtained from healthy volunteers and ovarian carcinoma patients. Our results also demonstrate an increased amount of detectable cfDNA in patients with cancer. Proteomic analysis of the same biomolecule coronas revealed the presence of histone proteins, suggesting an indirect, nucleosome-mediated NP-cfDNA interaction. The finding of cfDNA as part of the NP corona, offers a previously unreported new scope regarding the chemical composition of the 'biomolecule corona' and opens up new possibilities for the potential exploitation of the biomolecule corona for the enrichment and analysis of blood-circulating nucleic acids.

Implications of Biomolecular Corona for Molecular Imaging

The development of nanoparticle probes has opened up new possibilities for molecular imaging in the era of precision medicine. There are a wide range of nanoprobes that are being used for various modalities that have demonstrated promising potential in early detection, disease monitoring, and theranostics. However, the rate of successful clinical translation of the nanoprobes is very low and is affected by the lack of our understanding about nanoparticle interaction with biological fluids after systemic administration, thus representing an unmet clinical need. One of the poorly understood issues relates to the formation of biomolecular corona, a layer of biomolecules formed on the surface of nanoscale materials during their interactions with biological fluids. The biomolecular corona has several significant effects on the biodistribution of nanoprobes and their imaging ability by (i) reducing their targeting efficacy and (ii) affecting the intrinsic imaging properties (e.g., contrast capacity of magnetic nanoprobes). This review provides insights on the importance of considering biomolecular corona in the development of nanoprobes, which may enable their more efficient utilization for molecular imaging applications.

A materials-science perspective on tackling COVID-19

The ongoing SARS-CoV-2 pandemic highlights the importance of materials science in providing tools and technologies for antiviral research and treatment development. In this Review, we discuss previous efforts in materials science in developing imaging systems and microfluidic devices for the in-depth and real-time investigation of viral structures and transmission, as well as material platforms for the detection of viruses and the delivery of antiviral drugs and vaccines. We highlight the contribution of materials science to the manufacturing of personal protective equipment and to the design of simple, accurate and low-cost virus-detection devices. We then investigate future possibilities of materials science in antiviral research and treatment development, examining the role of materials in antiviral-drug design, including the importance of synthetic material platforms for organoids and organs-on-a-chip, in drug delivery and vaccination, and for the production of medical equipment. Materials-science-based technologies not only contribute to the ongoing SARS-CoV-2 research efforts but can also provide platforms and tools for the understanding, protection, detection and treatment of future viral diseases.

Nanoparticles in the Biological Context: Surface Morphology and Protein Corona Formation

A recent paper demonstrated that the formation of a protein corona is not a general property of all types of nanosized objects. In fact, it varies between a massive aggregation of plasma proteins onto the nanoparticle down to traces (e.g., a few proteins per 10 nanoparticles), which can only be determined by mass spectrometry in comparison to appropriate negative controls and background subtraction. Here, differences between various types of nanosized objects are discussed in order to determine general structure-property-relations from a physico-chemical viewpoint. It is highlighted that "not all nanoparticles are alike" and shown that their internal morphology, especially the difference between a strongly hydrated/swollen shell versus a sharp "hard" surface and its accessibility, is most relevant for biomedical applications.

Tandem-Mass-Tag Based Proteomic Analysis Facilitates Analyzing Critical Factors of Porous Silicon Nanoparticles in Determining Their Biological Responses under Diseased Condition

The analysis of nanoparticles' biocompatibility and immunogenicity is mostly performed under a healthy condition. However, more clinically relevant evaluation conducted under pathological condition is less known. Here, the immunogenicity and bio-nano interactions of porous silicon nanoparticles (PSi NPs) are evaluated in an acute liver inflammation mice model. Interestingly, a new mechanism in which PSi NPs can remit the hepatocellular damage and inflammation activation in a surface dependent manner through protein corona formation, which perturbs the inflammation by capturing the pro-inflammatory signaling proteins that are inordinately excreted or exposed under pathological condition, is found. This signal sequestration further attenuates the nuclear factor κB pathway activation and cytokines production from macrophages. Hence, the study proposes a potential mechanism for elucidating the altered immunogenicity of nanomaterials under pathological conditions, which might further offer insights to establish harmonized standards for assessing the biosafety of biomaterials in a disease-specific or personalized manner.

Protein corona fingerprinting to differentiate sepsis from non-infectious systemic inflammation

Rapid and accurate diagnosis of sepsis remains clinically challenging. The lack of specific biomarkers that can differentiate sepsis from non-infectious systemic inflammatory diseases often leads to excessive antibiotic treatment. Novel diagnostic tests are urgently needed to rapidly and accurately diagnose sepsis and enable effective treatment. Despite investment in cutting-edge technologies available today, the discovery of disease-specific biomarkers in blood remains extremely difficult. The highly dynamic environment of plasma restricts access to vital diagnostic information that can be obtained by proteomic analysis. Here, we employed clinically used lipid-based nanoparticles (AmBisome®) as an enrichment platform to analyze the human plasma proteome in the setting of sepsis. We exploited the spontaneous interaction of plasma proteins with nanoparticles (NPs) once in contact, called the 'protein corona', to discover previously unknown disease-specific biomarkers for sepsis diagnosis. Plasma samples obtained from non-infectious acute systemic inflammation controls and sepsis patients were incubated ex vivo with AmBisome® liposomes, and the resultant protein coronas were thoroughly characterised and compared by mass spectrometry (MS)-based proteomics. Our results demonstrate that the proposed nanoparticle enrichment technology enabled the discovery of 67 potential biomarker proteins that could reproducibly differentiate non-infectious acute systemic inflammation from sepsis. This study provides proof-of-concept evidence that nanoscale-based 'omics' enrichment technologies have the potential to substantially improve plasma proteomics analysis and to uncover novel biomarkers in a challenging clinical setting.

Tuning liposome composition to modulate corona formation in human serum and cellular uptake

Nano-sized objects such as liposomes are modified by adsorption of biomolecules in biological fluids. The resulting corona critically changes nanoparticle behavior at cellular level. A better control of corona composition could allow to modulate uptake by cells. Within this context, in this work, liposomes of different charge were prepared by mixing negatively charged and zwitterionic lipids to different ratios. The series obtained was used as a model system with tailored surface properties to modulate corona composition and determine the effects on liposome interactions with cells. Uptake efficiency and uptake kinetics of the different liposomes were determined by flow cytometry and fluorescence imaging. Particular care was taken in optimizing the methods to isolate the corona forming in human serum to prevent liposome agglomeration and to exclude residual free proteins, which could confuse the results. Thanks to the optimized methods, mass spectrometry of replicate corona isolations showed excellent reproducibility and this allowed semi-quantitative analysis to determine for each formulation the most abundant proteins in the corona. The results showed that by changing the fraction of zwitterionic and charged lipids in the bilayer, the amount and identity of the most abundant proteins adsorbed from serum differed. Interestingly, the formulations also showed very different uptake kinetics. Similar approaches can be used to tune lipid composition in a systematic way in order to obtain formulations with the desired corona and cell uptake behavior. STATEMENT OF SIGNIFICANCE: Liposomes and other nano-sized objects when introduced in biological fluids are known to adsorb biomolecules forming the so-called nanoparticle corona. This layer strongly affects the subsequent interactions of liposomes with cells. Here, by tuning lipid composition in a systematic way, a series of liposomes with tailored surface properties has been prepared to modulate the corona forming in human serum. Liposomes with very different cellular uptake kinetics have been obtained and their corona was identified in order to determine the most enriched proteins on the different formulations. By combining corona composition and uptake kinetics candidate corona proteins associated with reduced or increased uptake by cells can be identified and the liposome formulation can be tuned to obtain the desired uptake behavior.

Nanoparticle-enabled blood tests for early detection of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is often detected too late to allow adequate treatments with the result that patients are condemned to sufferings and early death. Most efforts have been therefore aimed at identifying sensitive PDAC biomarkers. Although biomarkers have numerous advantages, sample size, intra-individual variability, existence of several biases and confounding variables and cost of investigation make their clinical application challenging. In recent years, nanotechnology is providing new options for early cancer detection. Among recent discoveries, the concept is emerging that the protein corona, i.e. the layer of plasma proteins that surrounds nanomaterials in bodily fluids, is personalized. In particular, the protein corona of cancer patients is significantly different from that of healthy individuals. Herein, we review this concept with a particular focus on clinical relevance. We also discuss the recently developed nanoparticle-enabled blood (NEB) tests that demonstrated to be promising in discriminating PDAC patients from healthy volunteers by global change of the nanoparticle-protein corona. We conclude with a critical discussion of research perspectives aimed at further improving the prediction ability of the test.

Bare Iron Oxide Nanoparticles: Surface Tunability for Biomedical, Sensing and Environmental Applications

Surface modification is widely assumed as a mandatory prerequisite for the real applicability of iron oxide nanoparticles. This is aimed to endow prolonged stability, electrolyte and pH tolerance as well as a desired specific surface chemistry for further functionalization to these materials. Nevertheless, coating processes have negative consequences on the sustainability of nanomaterial production contributing to high costs, heavy environmental impact and difficult scalability. In this view, bare iron oxide nanoparticles (BIONs) are arousing an increasing interest and the properties and advantages of pristine surface chemistry of iron oxide are becoming popular among the scientific community. In the authors’ knowledge, rare efforts were dedicated to the use of BIONs in biomedicine, biotechnology, food industry and environmental remediation. Furthermore, literature lacks examples highlighting the potential of BIONs as platforms for the creation of more complex nanostructured architectures, and emerging properties achievable by the direct manipulation of pristine iron oxide surfaces have been little studied. Based on authors’ background on BIONs, the present review is aimed at providing hints on the future expansion of these nanomaterials emphasizing the opportunities achievable by tuning their pristine surfaces.

Potential clinical applications of the personalized, disease-specific protein corona on nanoparticles

Nanoscale objects lose their original identity once in contact with biological fluids and get a new biological identity, referred to as a protein corona (PC). The PC modifies many of the physicochemical properties of nanoparticles (NPs), including surface charge, size, and aggregation state. These changes, in turn, affect the biological fate of NPs, including their biodistribution, pharmacokinetics, and therapeutic efficacy. It is well known that even small differences in the composition of a protein source (e.g., plasma and serum) can considerably change the composition of the corona formed on the surface of the same NPs. Recently, it has been shown that the PC is intensely affected by the patient's specific disease. Consequently, the same nanomaterial incubated with proteins of biological fluids belonging to patients with different pathologies adsorbs protein coronas with different compositions, giving rise to the concept of the personalized protein corona (PPC). Herein, we review recent advances on the topic of PPC, with a particular focus on their clinical significance.

Interplay of protein corona and immune cells controls blood residency of liposomes

In vivo liposomes, like other types of nanoparticles, acquire a totally new 'biological identity' due to the formation of a biomolecular coating known as the protein corona that depends on and modifies the liposomes' synthetic identity. The liposome-protein corona is a dynamic interface that regulates the interaction of liposomes with the physiological environment. Here we show that the biological identity of liposomes is clearly linked to their sequestration from peripheral blood mononuclear cells (PBMCs) of healthy donors that ultimately leads to removal from the bloodstream. Pre-coating liposomes with an artificial corona made of human plasma proteins drastically reduces capture by circulating leukocytes in whole blood and may be an effective strategy to enable prolonged circulation in vivo. We conclude with a critical assessment of the key concepts of liposome technology that need to be reviewed for its definitive clinical translation.

Converting the personalized biomolecular corona of graphene oxide nanoflakes into a high-throughput diagnostic test for early cancer detection

Advances in nanotechnology are introducing the exciting possibility of cancer identification at early stages via analysis of the personalized biomolecular corona (BC), i.e. the dynamic "halo" of proteins that adsorbs onto NPs following exposure to patients' plasma. In this study, we develop a blood test for early cancer detection based on the characterization of the BC that forms around Graphene Oxide (GO) nanoflakes. Among its elective properties, GO binds low amounts of albumin, the most abundant protein in the blood and one of the most enriched proteins in the BC of many nanomaterials. This unique property of GO allows strong adsorption of poorly concentrated plasma proteins without abundant protein depletion. In our study, GO nanometric flakes have been used to analyze BCs from 50 subjects, half of them diagnosed with pancreatic cancer and half of them being healthy volunteers. Pancreatic cancer was chosen as the model of a high mortality disease with poor survival rates due to its delayed diagnosis. The receiver operating characteristic (ROC) curve analysis was applied to measure the diagnostic accuracy of the BC-based test. We obtained an area under the curve (AUC) of 0.96 and the test discriminated cancer patients from healthy subjects with a sensitivity of 92%. Finally, a double-blind validation was made using a second test dataset (10 healthy subjects + 10 pancreatic cancer patients) and it confirmed the results obtained on the first training dataset. Being highly accurate, fast, inexpensive and easy to perform, we believe that the BC-enabled blood test has the potential to become a turning point in early detection of cancer and other diseases.

The biomolecular corona of gold nanoparticles in a controlled microfluidic environment

Nanoparticles (NPs) exposed to biological media are coated by proteins and other biomolecules forming a biomolecular corona (BC) on the particle surface. Recent studies have shown that shear stress as that created by laminar fluid flow generates more complex coronas with systematic changes in composition with respect to counterparts formed under static incubation. However, in most studies reported so far, dynamic environments have been produced by peristaltic pumps and comparing experimental results appears challenging. On the other side, generating shear stress by microfluidic devices could help to remove user variability and ensure better reproducibility of experimental data. This study was therefore aimed at exploring formation of NP-BC in a microfluidic environment. To this end, 100 nm gold nanoparticles and human plasma (HP) were used as models for nano-formulation and biological medium. We injected gold nanoparticles and HP in each of the islets of a remote-controlled microfluidic cartridge. Static incubation was used as a reference. BC-decorated NPs were thoroughly characterized by dynamic light scattering (DLS), micro-electrophoresis (ME), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) and nano-liquid chromatography tandem mass spectrometry (nano-LC MS/MS). By varying the incubation time from 30 s to 2.5 min we demonstrate that BC is already determined by the earliest exposure time point and does not appreciably evolve in time. DLS and ME results demonstrate that the BC formed in a microfluidic chip is thicker and more negatively charged than its counterpart formed under static incubation. SDS-PAGE and nano-LC MS/MS revealed that the incubation procedure had a major effect on BC composition. As an example, immunoglobulins are the most abundant plasma proteins of the BC generated in a microfluidic environment (relative protein abundance ∼30%), while tissue leakage proteins (relative protein abundance ∼26%) are the most enriched proteins when the BC is formed upon static incubation. Potential implications in emerging biomedical research arenas are discussed.