Engineering at the nano-bio interface: harnessing the protein corona towards nanoparticle design and function

Sterile inflammation induced by respirable micro and nano polystyrene particles in the pathogenesis of pulmonary diseases

Sterile inflammation is involved in the lung pathogenesis induced by respirable particles, including micro- and nanoplastics. Their increasing amounts in the ambient and in indoor air pose a risk to human health. In two human cell lines (A549 and THP-1) we assessed the proinflammatory behavior of polystyrene nanoplastics (nPS) and microplastics (mPS) (Ø 0.1 and 1 μm). Reproducing environmental aging, in addition to virgin, the cells were exposed to oxidized nPS/mPS. To study the response of the monocytes to the inflammatory signal transmitted by the A549 through the release of soluble factors (e.g. alarmins and cytokines), THP-1 cells were also exposed to the supernatants of previously nPS/mPS-treated A549. After dynamic-light-scattering (DLS) analysis and protein measurements for the assessment of protein corona in nPS/mPS, real-time PCR and enzyme-linked-immunosorbent (ELISA) assays were performed in exposed cells. The pro-inflammatory effects of v- and ox-nPS/mPS were attested by the imbalance of the Bax/Bcl-2 ratio in A549, which was able to trigger the inflammatory cascade, inhibiting the immunologically silent apoptosis. The involvement of NFkB was confirmed by the overexpression of p65 after exposure to ox-nPS and v- and ox-mPS. The fast and higher levels of IL-1β, only in THP-1 cells, underlined the NLPR3 inflammasome activation.

Dye-Based Fluorescent Organic Nanoparticles, New Promising Tools for Optogenetics

Dye-based fluorescent organic nanoparticles are a specific class of nanoparticles obtained by nanoprecipitation in water of pure dyes only. While the photophysical and colloidal properties of the nanoparticles strongly depend on the nature of the aggregated dyes, their excellent brightness in the visible and in the near infrared make these nanoparticles a unique and versatile platform for in vivo application. This article examines the promising utilization of these nanoparticles for in vivo optogenetics applications. Their photophysical properties as well as their biocompatibility and their capacity to activate Chrimson opsin in vivo through the fluorescence reabsorption process are demonstrated. Additionally, an illustrative example of employing these nanoparticles in fear reduction in mice through closed-loop stimulation is presented. Through an optogenetic methodology, the nanoparticles demonstrate an ability to selectively manipulate neurons implicated in the fear response and diminish the latter. Dye-based fluorescent organic nanoparticles represent a promising and innovative strategy for optogenetic applications, holding substantial potential in the domain of translational neuroscience. This work paves the way for novel therapeutic modalities for neurological and neuropsychiatric disorders.

Stealth and Biocompatible Gold Nanoparticles through Surface Coating with a Zwitterionic Derivative of Glutathione

Gold nanoparticles (AuNPs) hold promise in biomedicine, but challenges like aggregation, protein corona formation, and insufficient biocompatibility must be thoroughly addressed before advancing their clinical applications. Designing AuNPs with specific protein corona compositions is challenging, and strategies for corona elimination, such as coating with polyethylene glycol (PEG), have limitations. In this study, we introduce a commercially available zwitterionic derivative of glutathione, glutathione monoethyl ester (GSHzwt), for the surface coating of colloidal AuNPs. Particles coated with GSHzwt were investigated alongside four other AuNPs coated with various ligands, including citrate ions, tiopronin, glutathione, cysteine, and PEG. We then undertook a head-to-head comparison of these AuNPs to assess their behavior in biological fluid. GSHzwt-coated AuNPs exhibited exceptional resistance to aggregation and protein adsorption. The particles could also be readily functionalized with biotin and interact with streptavidin receptors in human plasma. Additionally, they exhibited significant blood compatibility and noncytotoxicity. In conclusion, GSHzwt provides a practical and easy method for the surface passivation of AuNPs, creating "stealth" particles for potential clinical applications.

Electrophoresis-Based Approach for Characterizing Dendrimer-Protein Interactions: A Proof-of-Concept Study

Improving the clinical translation of nanomedicine requires better knowledge about how nanoparticles interact with biological environments. As researchers are recognizing the importance of understanding the protein corona and characterizing how nanocarriers respond in biological systems, new tools and techniques are needed to analyze nanocarrier-protein interactions, especially for smaller size (<10 nm) nanoparticles like polyamidoamine (PAMAM) dendrimers. Here, we developed a streamlined, semiquantitative approach to assess dendrimer-protein interactions using a nondenaturing electrophoresis technique combined with mass spectrometry. With this protocol, we detect fluorescently tagged dendrimers and proteins simultaneously, enabling us to analyze when dendrimers migrate with proteins. We found that PAMAM dendrimers mostly interact with complement proteins, particularly C3 and C4a, which aligns with previously published data, verifying that our approach can be used to isolate and identify dendrimer-protein interactions.

Receptor Ligand-Free Mesoporous Silica Nanoparticles: A Streamlined Strategy for Targeted Drug Delivery across the Blood-Brain Barrier

Mesoporous silica nanoparticles (MSNs) represent a promising avenue for targeted brain tumor therapy. However, the blood-brain barrier (BBB) often presents a formidable obstacle to efficient drug delivery. This study introduces a ligand-free PEGylated MSN variant (RMSN25-PEG-TA) with a 25 nm size and a slight positive charge, which exhibits superior BBB penetration. Utilizing two-photon imaging, RMSN25-PEG-TA particles remained in circulation for over 24 h, indicating significant traversal beyond the cerebrovascular realm. Importantly, DOX@RMSN25-PEG-TA, our MSN loaded with doxorubicin (DOX), harnessed the enhanced permeability and retention (EPR) effect to achieve a 6-fold increase in brain accumulation compared to free DOX. In vivo evaluations confirmed the potent inhibition of orthotopic glioma growth by DOX@RMSN25-PEG-TA, extending survival rates in spontaneous brain tumor models by over 28% and offering an improved biosafety profile. Advanced LC-MS/MS investigations unveiled a distinctive protein corona surrounding RMSN25-PEG-TA, suggesting proteins such as apolipoprotein E and albumin could play pivotal roles in enabling its BBB penetration. Our results underscore the potential of ligand-free MSNs in treating brain tumors, which supports the development of future drug-nanoparticle design paradigms.

Critical Review: Uptake and Translocation of Organic Nanodelivery Vehicles in Plants

Nanodelivery vehicles (NDVs) are engineered nanomaterials (ENMs) that, within the agricultural sector, have been investigated for their ability to improve uptake and translocation of agrochemicals, control release, or target specific tissues or subcellular compartments. Both inorganic and organic NDVs have been studied for agrochemical delivery in the literature, but research on the latter has been slower to develop than the literature on the former. Since the two classes of nanomaterials exhibit significant differences in surface chemistry, physical deformability, and even colloidal stability, trends that apply to inorganic NDVs may not hold for organic NDVs, and vice versa. We here review the current literature on the uptake, translocation, biotransformation, and cellular and subcellular internalization of organic NDVs in plants following foliar or root administration. A background on nanomaterials and plant physiology is provided as a leveling ground for researchers in the field. Trends in uptake and translocation are examined as a function of NDV properties and compared to those reported for inorganic nanomaterials. Methods for assessing fate and transport of organic NDVs in plants (a major bottleneck in the field) are discussed. We end by identifying knowledge gaps in the literature that must be understood in order to rationally design organic NDVs for precision agrochemical nanodelivery.

Fe3O4SPIONs in cancer theranostics-structure versus interactions with proteins and methods of their investigation

As the second leading cause of death worldwide, neoplastic diseases are one of the biggest challenges for public health care. Contemporary medicine seeks potential tools for fighting cancer within nanomedicine, as various nanomaterials can be used for both diagnostics and therapies. Among those of particular interest are superparamagnetic iron oxide nanoparticles (SPIONs), due to their unique magnetic properties,. However, while the number of new SPIONs, suitably modified and functionalized, designed for medical purposes, has been gradually increasing, it has not yet been translated into the number of approved clinical solutions. The presented review covers various issues related to SPIONs of potential theranostic applications. It refers to structural considerations (the nanoparticle core, most often used modifications and functionalizations) and the ways of characterizing newly designed nanoparticles. The discussion about the phenomenon of protein corona formation leads to the conclusion that the scarcity of proper tools to investigate the interactions between SPIONs and human serum proteins is the reason for difficulties in introducing them into clinical applications. The review emphasizes the importance of understanding the mechanism behind the protein corona formation, as it has a crucial impact on the effectiveness of designed SPIONs in the physiological environment.

In Vitro and In Vivo Evaluation of the Pathology and Safety Aspects of Three- and Four-Way Junction RNA Nanoparticles

RNA therapeutics has advanced into the third milestone in pharmaceutical drug development, following chemical and protein therapeutics. RNA itself can serve as therapeutics, carriers, regulators, or substrates in drug development. Due to RNA's motile, dynamic, and deformable properties, RNA nanoparticles have demonstrated spontaneous targeting and accumulation in cancer vasculature and fast excretion through the kidney glomerulus to urine to prevent possible interactions with healthy organs. Furthermore, the negatively charged phosphate backbone of RNA results in general repulsion from negatively charged lipid cell membranes for further avoidance of vital organs. Thus, RNA nanoparticles can spontaneously enrich tumor vasculature and efficiently enter tumor cells via specific targeting, while those not entering the tumor tissue will clear from the body quickly. These favorable parameters have led to the expectation that RNA has low or little toxicity. RNA nanoparticles have been well characterized for their anticancer efficacy; however, little detail on RNA nanoparticle pathology and safety is known. Here, we report the in vitro and in vivo assessment of the pathology and safety aspects of different RNA nanoparticles including RNA three-way junction (3WJ) harboring 2'-F modified pyrimidine, folic acid, and Survivin siRNA, as well as the RNA four-way junction (4WJ) harboring 2'-F modified pyrimidine and 24 copies of SN38. Both animal models and patient serum were investigated. In vitro studies include hemolysis, platelet aggregation, complement activation, plasma coagulation, and interferon induction. In vivo studies include hematoxylin and eosin (H&E) staining, hematological and biochemical analysis as the serum profiling, and animal organ weight study. No significant toxicity, side effect, or immune responses were detected during the extensive safety evaluations of RNA nanoparticles. These results further complement previous cancer inhibition studies and demonstrate RNA nanoparticles as an effective and safe drug delivery vehicle for future clinical translations.

RNA nanostructures for targeted drug delivery and imaging

The RNA molecule plays a pivotal role in many biological processes by relaying genetic information, regulating gene expression, and serving as molecular machines and catalyzers. This inherent versatility of RNA has fueled significant advancements in the field of RNA nanotechnology, driving the engineering of complex nanoscale architectures toward biomedical applications, including targeted drug delivery and bioimaging. RNA polymers, serving as building blocks, offer programmability and predictability of Watson-Crick base pairing, as well as non-canonical base pairing, for the construction of nanostructures with high precision and stoichiometry. Leveraging the ease of chemical modifications to protect the RNA from degradation, researchers have developed highly functional and biocompatible RNA architectures and integrated them into preclinical studies for the delivery of payloads and imaging agents. This review offers an educational introduction to the use of RNA as a biopolymer in the design of multifunctional nanostructures applied to targeted delivery in vivo, summarizing physical and biological barriers along with strategies to overcome them. Furthermore, we highlight the most recent progress in the development of both small and larger RNA nanostructures, with a particular focus on imaging reagents and targeted cancer therapeutics in pre-clinical models and provide insights into the prospects of this rapidly evolving field.

Background free in vivo29Si MR imaging with hyperpolarized PEGylated silicon nanoparticles

This study demonstrated the potential of 50 nm PEGylated Si NPs for high-resolution in vivo29Si MR imaging, emphasizing their biocompatibility and water dispersibility. The acquisition of in vivo Si MR images using the lowest reported dose after subcutaneous and intraperitoneal administration opens new avenues for future 29Si MR studies.

The Hybrid Nano-Biointerface between Proteins/Peptides and Two-Dimensional Nanomaterials

In typical protein-nanoparticle surface interactions, the biomolecule surface binding and consequent conformational changes are intermingled with each other and are pivotal to the multiple functional properties of the resulting hybrid bioengineered nanomaterial. In this review, we focus on the peculiar properties of the layer formed when biomolecules, especially proteins and peptides, face two-dimensional (2D) nanomaterials, to provide an overview of the state-of-the-art knowledge and the current challenges concerning the biomolecule coronas and, in general, the 2D nano-biointerface established when peptides and proteins interact with the nanosheet surface. Specifically, this review includes both experimental and simulation studies, including some recent machine learning results of a wide range of nanomaterial and peptide/protein systems.

Stabilizing Polymer Coatings Alter the Protein Corona of DNA Origami and Can Be Engineered to Bias the Cellular Uptake

With DNA-based nanomaterials being designed for applications in cellular environments, the need arises to accurately understand their surface interactions toward biological targets. As for any material exposed to protein-rich cell culture conditions, a protein corona will establish around DNA nanoparticles, potentially altering the a-priori designed particle function. Here, we first set out to identify the protein corona around DNA origami nanomaterials, taking into account the application of stabilizing block co-polymer coatings (oligolysine-1kPEG or oligolysine-5kPEG) widely used to ensure particle integrity. By implementing a label-free methodology, the distinct polymer coating conditions show unique protein profiles, predominantly defined by differences in the molecular weight and isoelectric point of the adsorbed proteins. Interestingly, none of the applied coatings reduced the diversity of the proteins detected within the specific coronae. We then biased the protein corona through pre-incubation with selected proteins and show significant changes in the cell uptake. Our study contributes to a deeper understanding of the complex interplay between DNA nanomaterials, proteins, and cells at the bio-interface.

The role of protein corona on nanodrugs for organ-targeting and its prospects of application

Nowadays, nanodrugs become a hotspot in the high-end medical field. They have the ability to deliver drugs to reach their destination more effectively due to their unique properties and flexible functionalization. However, the fate of nanodrugs in vivo is not the same as those presented in vitro, which indeed influenced their therapeutic efficacy in vivo. When entering the biological organism, nanodrugs will first come into contact with biological fluids and then be covered by some biomacromolecules, especially proteins. The proteins adsorbed on the surface of nanodrugs are known as protein corona (PC), which causes the loss of prospective organ-targeting abilities. Fortunately, the reasonable utilization of PC may determine the organ-targeting efficiency of systemically administered nanodrugs based on the diverse expression of receptors on cells in different organs. In addition, the nanodrugs for local administration targeting diverse lesion sites will also form unique PC, which plays an important role in the therapeutic effect of nanodrugs. This article introduced the formation of PC on the surface of nanodrugs and summarized the recent studies about the roles of diversified proteins adsorbed on nanodrugs and relevant protein for organ-targeting receptor through different administration pathways, which may deepen our understanding of the role that PC played on organ-targeting and improve the therapeutic efficacy of nanodrugs to promote their clinical translation.

Nanoparticle protein corona: from structure and function to therapeutic targeting

Nanoparticle (NP)-based therapeutics have ushered in a new era in translational medicine. However, despite the clinical success of NP technology, it is not well-understood how NPs fundamentally change in biological environments. When introduced into physiological fluids, NPs are coated by proteins, forming a protein corona (PC). The PC has the potential to endow NPs with a new identity and alter their bioactivity, stability, and destination. Additionally, the conformation of proteins is sensitive to their physical and chemical surroundings. Therefore, biological factors and protein-NP-interactions can induce changes in the conformation and orientation of proteins in vivo. Since the function of a protein is closely connected to its folded structure, slight differences in the surrounding environment as well as the surface characteristics of the NP materials may cause proteins to lose or gain a function. As a result, this can alter the downstream functionality of the NPs. This review introduces the main biological factors affecting the conformation of proteins associated with the PC. Then, four types of NPs with extensive utility in biomedical applications are described in greater detail, focusing on the conformation and orientation of adsorbed proteins. This is followed by a discussion on the instances in which the conformation of adsorbed proteins can be leveraged for therapeutic purposes, such as controlling protein conformation in assembled matrices in tissue, as well as controlling the PC conformation for modulating immune responses. The review concludes with a perspective on the remaining challenges and unexplored areas at the interface of PC and NP research.

Design of Synthetic Hydrogel Compositions for Noncovalent Protein Recognition

Multifunctional hydrogels composed of segments with ionizable, hydrophilic, and hydrophobic monomers have been optimized for sensing, bioseparation, and therapeutic applications. While the "biological identity" of bound proteins from biofluids underlies device performance in each context, design rules that predict protein binding outcomes from hydrogel design parameters are lacking. Uniquely, hydrogel designs that influence protein affinity (e.g., ionizable monomers, hydrophobic moieties, conjugated ligands, cross-linking) also affect physical properties (e.g., matrix stiffness, volumetric swelling). Here, we evaluated the influence of hydrophobic comonomer steric bulk and quantity on the protein recognition characteristics of ionizable microscale hydrogels (microgels) while controlling for swelling. Using a library synthesis approach, we identified compositions that balance the practical balance between protein-microgel affinity and the loaded mass at saturation. Intermediate quantities (10-30 mol %) of hydrophobic comonomer increased the equilibrium binding of certain model proteins (lysozyme, lactoferrin) in buffer conditions that favored complementary electrostatic interactions. Solvent-accessible surface area analysis of model proteins identified arginine content as highly predictive of model proteins' binding to our library of hydrogels containing acidic and hydrophobic comonomers. Taken together, we established an empirical framework for characterizing the molecular recognition properties of multifunctional hydrogels. Our study is the first to identify solvent-accessible arginine as an important predictor for protein binding to hydrogels containing both acidic and hydrophobic subunits.

Blood Protein Exclusion from Polymer Brushes

We report interactions between adsorbed copolymers of poly(ethylene glycol) (PEG) in the presence of two abundant blood proteins, serum albumin and an immunoglobulin G, up to physiological blood concentrations. We directly and nonintrusively measure interactions between PEG triblock copolymers (PEG-PPO-PEG) adsorbed to hydrophobic colloids and surfaces using Total Internal Reflection Microscopy, which provides kT- and nanometer-scale resolution of interaction potentials (energy vs separation). In the absence of protein, adsorbed PEG copolymer repulsion is consistent with dimensions and architectures of PEG brushes on both colloids and surfaces. In the presence of proteins, we observe concentration dependent depletion attraction and no change to brush repulsion, indicating protein exclusion from PEG brushes. Because positive and negative protein adsorption are mutually exclusive, our observations of concentration dependent depletion attraction with no change to brush repulsion unambiguously indicate the absence of protein coronas at physiological protein concentrations. These findings demonstrate a direct sensitive approach to determine interactions between proteins and particle/surface coatings important to diverse biotechnology applications.

Nanomaterials in anticancer applications and their mechanism of action - A review

The current challenges in cancer treatment using conventional therapies have made the emergence of nanotechnology with more advancements. The exponential growth of nanoscience has drawn to develop nanomaterials (NMs) with therapeutic activities. NMs have enormous potential in cancer treatment by altering the drug toxicity profile. Nanoparticles (NPs) with enhanced surface characteristics can diffuse more easily inside tumor cells, thus delivering an optimal concentration of drugs at tumor site while reducing the toxicity. Cancer cells can be targeted with greater affinity by utilizing NMs with tumor specific constituents. Furthermore, it bypasses the bottlenecks of indiscriminate biodistribution of the antitumor agent and high administration dosage. Here, we focus on the recent advances on the use of various nanomaterials for cancer treatment, including targeting cancer cell surfaces, tumor microenvironment (TME), organelles, and their mechanism of action. The paradigm shift in cancer management is achieved through the implementation of anticancer drug delivery using nano routes.

Biological Features of Nanoparticles: Protein Corona Formation and Interaction with the Immune System

Nanoparticles (NPs) are versatile candidates for nanomedical applications due to their unique physicochemical properties. However, their clinical applicability is hindered by their undesirable recognition by the immune system and the consequent immunotoxicity, as well as their rapid clearance in vivo. After injection, NPs are usually covered with layers of proteins, called protein coronas (PCs), which alter their identity, biodistribution, half-life, and efficacy. Therefore, the characterization of the PC is for in predicting the fate of NPs in vivo. The aim of this review was to summarize the state of the art regarding the intrinsic factors closely related to the NP structure, and extrinsic factors that govern PC formation in vitro. In addition, well-known opsonins, including complement, immunoglobulins, fibrinogen, and dysopsonins, such as histidine-rich glycoprotein, apolipoproteins, and albumin, are described in relation to their role in NP detection by immune cells. Particular emphasis is placed on their role in mediating the interaction of NPs with innate and adaptive immune cells. Finally, strategies to reduce PC formation are discussed in detail.

How Nanoparticles Open the Paracellular Route of Biological Barriers: Mechanisms, Applications, and Prospects

Biological barriers are essential physiological protective systems and obstacles to drug delivery. Nanoparticles (NPs) can access the paracellular route of biological barriers, either causing adverse health impacts on humans or producing therapeutic opportunities. This Review introduces the structural and functional influences of NPs on the key components that govern the paracellular route, mainly tight junctions, adherens junctions, and cytoskeletons. Furthermore, we evaluate their interaction mechanisms and address the influencing factors that determine the ability of NPs to open the paracellular route, which provides a better knowledge of how NPs can open the paracellular route in a safer and more controllable way. Finally, we summarize limitations in the research models and methodologies of the existing research in the field and provide future research direction. This Review demonstrates the in-depth causes for the reversible opening or destruction of the integrity of barriers generated by NPs; more importantly, it contributes insights into the design of NP-based medications to boost paracellular drug delivery efficiency.

"Targeting Design" of Nanoparticles in Tumor Therapy

Tumor-targeted therapy based on nanoparticles is a popular research direction in the biomedical field. After decades of research and development, both the passive targeting ability of the inherent properties of NPs and the active targeting based on ligand receptor interaction have gained deeper understanding. Unfortunately, most targeted delivery strategies are still in the preclinical trial stage, so it is necessary to further study the biological fate of particles in vivo and the interaction mechanism with tumors. This article reviews different targeted delivery strategies based on NPs, and focuses on the physical and chemical properties of NPs (size, morphology, surface and intrinsic properties), ligands (binding number/force, activity and species) and receptors (endocytosis, distribution and recycling) and other factors that affect particle targeting. The limitations and solutions of these factors are further discussed, and a variety of new targeting schemes are introduced, hoping to provide guidance for future targeting design and achieve the purpose of rapid transformation of targeted particles into clinical application.

Artificial engineering of the protein corona at bio-nano interfaces for improved cancer-targeted nanotherapy

Nanoparticles (NPs) have been demonstrated in numerous applications as anticancer, antibacterial and antioxidant agents. Artificial engineering of protein interactions with NPs in biological systems is crucial to develop potential NPs for drug delivery and cancer nanotherapy. The protein corona (PC) on the NP surface, displays an interface between biomacromolecules and NPs, governing their pharmacokinetics and pharmacodynamics. Upon interaction of proteins with the NP surface, their surface features are modified and they can easily be removed from the circulation by the mononuclear phagocytic system (MPS). PC properties heavily depend on the biological microenvironment and NP surface physicochemical parameters. Based on this context, we have surveyed different approaches that have been used for artificial engineering of the PC composition on NP surfaces. We discuss the effects of NP size, shape, surface modifications (PEGylation, self-peptide, other polymers), and protein pre-coating on the PC properties. Additionally, other factors including protein source and structure, intravenous injection and the subsequent shear flow, plasma protein gradients, temperature and local heat transfer, and washing media are considered in the context of their effects on the PC properties and overall target cellular effects. Moreover, the effects of NP-PC complexes on cancer cells based on cellular interactions, organization of intracellular PC (IPC), targeted drug delivery (TDD) and regulation of burst drug release profile of nanoplatforms, enhanced biocompatibility, and clinical applications were discussed followed by challenges and future perspective of the field. In conclusion, this paper can provide useful information to manipulate PC properties on the NP surface, thus trying to provide a literature survey to shorten their shipping from preclinical to clinical trials and to lay the basis for a personalized PC.

How Nanotechniques Could Vitalize the O-GlcNAcylation-Targeting Approach for Cancer Therapy

Accumulated data indicated that many types of cancers have increased protein O-GlcNAcylation at cell surface and inside cells. The aberrant O-GlcNAcylation is considered a potential therapeutic target. Although several types of compounds capable of inhibiting O-GlcNAcylation have been developed, their low solubility, poor permeability and delivery efficiency have impeded the application for in vivo and pre-clinical studies. Nanocarriers have the advantages of controllable drug release and active cancer-targeting capability. Moreover, nanoparticles can improve drug delivery efficiency and reduce the non-specific distribution in normal tissues by the enhanced permeability and retention (EPR) effect in cancer. Taking the advantage of O-GlcNAc-specific antibodies or lectins, nanoparticles could further improve their cancer-targeting capability. Although nanocarriers targeting the canonical N- and O-linked glycosylation have been extensively investigated for cancer detection and therapy, application of nanotechniques for the specific targeting of O-GlcNAcylation has not been actively pursued. This review summarizes the general features of GlcNAcylation and its alterations in cancers. Analyses are focused on the following areas: How the nanocarriers may improve the solubility and/or cell permeability of O-GlcNAc transferase (OGT) inhibitors; The modification of nanocarriers with lectins or antibodies for active targeting of O-GlcNAc; The nanocarriers-mediated co-delivery of OGT inhibitors and conventional drugs, which may lead to synergistic effects. Unsolved issues impeding the research progression on O-GlcNAcylation-targeting scheme are also discussed.

Protein adsorption onto nanomaterials engineered for theranostic applications

The key role of biomolecule adsorption onto engineered nanomaterials for therapeutic and diagnostic purposes has been well recognized by the nanobiotechnology community, and our mechanistic understanding of nano-bio interactions has greatly advanced over the past decades. Attention has recently shifted to gaining active control of nano-bio interactions, so as to enhance the efficacy of nanomaterials in biomedical applications. In this review, we summarize progress in this field and outline directions for future development. First, we briefly review fundamental knowledge about the intricate interactions between proteins and nanomaterials, as unraveled by a large number of mechanistic studies. Then, we give a systematic overview of the ways that protein-nanomaterial interactions have been exploited in biomedical applications, including the control of protein adsorption for enhancing the targeting efficiency of nanomedicines, the design of specific protein adsorption layers on the surfaces of nanomaterials for use as drug carriers, and the development of novel nanoparticle array-based sensors based on nano-bio interactions. We will focus on particularly relevant and recent examples within these areas. Finally, we conclude this topical review with an outlook on future developments in this fascinating research field.

Structural changes in selected human proteins induced by exposure to quantum dots, their biological relevance and possible biomedical applications

Quantum dots (QDs) are semi-conductor luminescent nanocrystals usually of 2-10 nm diameter, attracting the significant attention in biomedical studies since emerged. Due to their unique optical and electronic properties, i.e. wide absorption spectra, narrow tunable emission bands or stable, bright photoluminescence, QDs seem to be ideally suited for multi-colour, simultaneous bioimaging and cellular labeling at the molecular level as new-generation probes. A highly reactive surface of QDs allows for conjugating them to biomolecules, what enables their direct binding to areas of interest inside or outside the cell for biosensing or targeted delivery. Particularly protein-QDs conjugates are current subjects of research, as features of QDs can be combined with protein specific functionalities and therefore used as a complex in variety of biomedical applications. It is known that QDs are able to interact with cells, organelles and macromolecules of the human body after administration. QDs are reported to cause changes at proteins level, including unfolding and three-dimensional structure alterations which might hamper proteins from performing their physiological functions and thereby limit the use of QD-protein conjugates in vivo. Moreover, these changes may trigger unwanted cellular outcomes as the effect of different signaling pathways activation. In this review, characteristics of QDs interactions with certain human proteins are presented and discussed. Besides that, the following manuscript provides an overview on structural changes of specific proteins exposed to QDs and their biological and biomedical relevance.

Unifying structural descriptors for biological and bioinspired nanoscale complexes

Biomimetic nanoparticles are known to serve as nanoscale adjuvants, enzyme mimics and amyloid fibrillation inhibitors. Their further development requires better understanding of their interactions with proteins. The abundant knowledge about protein-protein interactions can serve as a guide for designing protein-nanoparticle assemblies, but the chemical and biological inputs used in computational packages for protein-protein interactions are not applicable to inorganic nanoparticles. Analysing chemical, geometrical and graph-theoretical descriptors for protein complexes, we found that geometrical and graph-theoretical descriptors are uniformly applicable to biological and inorganic nanostructures and can predict interaction sites in protein pairs with accuracy >80% and classification probability ~90%. We extended the machine-learning algorithms trained on protein-protein interactions to inorganic nanoparticles and found a nearly exact match between experimental and predicted interaction sites with proteins. These findings can be extended to other organic and inorganic nanoparticles to predict their assemblies with biomolecules and other chemical structures forming lock-and-key complexes.

The Janus of Protein Corona on nanoparticles for tumor targeting, immunotherapy and diagnosis

The therapeutics based on nanoparticles (NPs) are considered as the promising strategy for tumor detection and treatment. However, one of the most challenges is the adsorption of biomolecules on NPs after their exposition to biological medium, leading unpredictable in vivo behaviors. The interactions caused by protein corona (PC) will influence the biological fate of NPs in either negative or positive ways, including (i) blood circulation, accumulation and penetration of NPs at targeting sites, and further cellular uptake in tumor targeting delivery; (ii) interactions between NPs and receptors on immune cells for immunotherapy. Besides, PC on NPs could be utilized as new biomarker in tumor diagnosis by identifying the minor change of protein concentration led by tumor growth and invasion in blood. Herein, the mechanisms of these PC-mediated effects will be introduced. Moreover, the recent advances about the strategies will be reviewed to reduce negative effects caused by PC and/or utilize positive effects of PC on tumor targeting, immunotherapy and diagnosis, aiming to provide a reasonable perspective to recognize PC with their applications.

Polymer-Conjugated Carbon Nanotubes for Biomolecule Loading

Nanomaterials have emerged as an invaluable tool for the delivery of biomolecules such as DNA and RNA, with various applications in genetic engineering and post-transcriptional genetic manipulation. Alongside this development, there has been an increasing use of polymer-based techniques, such as polyethylenimine (PEI), to electrostatically load polynucleotide cargoes onto nanomaterial carriers. However, there remains a need to assess nanomaterial properties, conjugation conditions, and biocompatibility of these nanomaterial-polymer constructs, particularly for use in plant systems. In this work, we develop mechanisms to optimize DNA loading on single-walled carbon nanotubes (SWNTs) with a library of polymer-SWNT constructs and assess DNA loading ability, polydispersity, and both chemical and colloidal stability. Counterintuitively, we demonstrate that polymer hydrolysis from nanomaterial surfaces can occur depending on polymer properties and attachment chemistries, and we describe mitigation strategies against construct degradation. Given the growing interest in delivery applications in plant systems, we also assess the stress response of plants to polymer-based nanomaterials and provide recommendations for future design of nanomaterial-based polynucleotide delivery strategies.

Polymer-Conjugated Carbon Nanotubes for Biomolecule Loading

Nanomaterials have emerged as an invaluable tool for the delivery of biomolecules such as DNA and RNA, with various applications in genetic engineering and post-transcriptional genetic manipulation. Alongside this development, there has been an increasing use of polymer-based techniques, such as polyethylenimine (PEI), to electrostatically load polynucleotide cargoes onto nanomaterial carriers. However, there remains a need to assess nanomaterial properties, conjugation conditions, and biocompatibility of these nanomaterial-polymer constructs, particularly for use in plant systems. In this work, we develop mechanisms to optimize DNA loading on single-walled carbon nanotubes (SWNTs) with a library of polymer-SWNT constructs and assess DNA loading ability, polydispersity, and both chemical and colloidal stability. Counterintuitively, we demonstrate that polymer hydrolysis from nanomaterial surfaces can occur depending on polymer properties and attachment chemistries, and we describe mitigation strategies against construct degradation. Given the growing interest in delivery applications in plant systems, we also assess the stress response of plants to polymer-based nanomaterials and provide recommendations for future design of nanomaterial-based polynucleotide delivery strategies.

Role of Ionic Strength in the Formation of Stable Supramolecular Nanoparticle-Protein Conjugates for Biosensing

Monolayer-protected gold nanoparticles (AuNPs) exhibit distinct physical and chemical properties depending on the nature of the ligand chemistry. A commonly employed NP monolayer comprises hydrophobic molecules linked to a shell of PEG and terminated with functional end group, which can be charged or neutral. Different layers of the ligand shell can also interact in different manners with proteins, expanding the range of possible applications of these inorganic nanoparticles. AuNP-fluorescent Green Fluorescent Protein (GFP) conjugates are gaining increasing attention in sensing applications. Experimentally, their stability is observed to be maintained at low ionic strength conditions, but not at physiologically relevant conditions of higher ionic strength, limiting their applications in the field of biosensors. While a significant amount of fundamental work has been done to quantify electrostatic interactions of colloidal nanoparticle at the nanoscale, a theoretical description of the ion distribution around AuNPs still remains relatively unexplored. We perform extensive atomistic simulations of two oppositely charged monolayer-protected AuNPs interacting with fluorescent supercharged GFPs co-engineered to have complementary charges. These simulations were run at different ionic strengths to disclose the role of the ionic environment on AuNP–GFP binding. The results highlight the capability of both AuNPs to intercalate ions and water molecules within the gold–sulfur inner shell and the different tendency of ligands to bend inward allowing the protein to bind not only with the terminal ligands but also the hydrophobic alkyl chains. Different binding stability is observed in the two investigated cases as a function of the ligand chemistry.

Strategy for Avoiding Protein Corona Inhibition of Targeted Drug Delivery by Linking Recombinant Affibody Scaffold to Magnetosomes

PURPOSE

Nanoparticles (NPs) decorated with functional ligands are promising candidates for cancer diagnosis and treatment. However, numerous studies have shown that chemically coupled targeting moieties on NPs lose their targeting capability in the biological milieu because they are shielded or covered by a "protein corona". Herein, we construct a functional magnetosome that recognizes and targets cancer cells even in the presence of protein corona.

METHODS

Magnetosomes (BMPs) were extracted from magnetotactic bacteria, M. gryphiswaldense (MSR-1), and decorated with trastuzumab (TZ) via affibody (RA) and glutaraldehyde (GA). The engineered BMPs are referred to as BMP-RA-TZ and BMP-GA-TZ. Their capacities to combine HER2 were detected by ELISA, the quantity of plasma corona proteins was analyzed using LC-MS. The efficiencies of targeting SK-BR-3 were demonstrated by confocal laser scanning microscopy and flow cytometry.

RESULTS

Both engineered BMPs contain up to ~0.2 mg TZ per mg of BMP, while the quantity of HER2 binding to BMP-RA-TZ is three times higher than that binding to BMP-GA-TZ. After incubation with normal human plasma or IgG-supplemented plasma, GA-TZ-containing BMPs have larger hydrated radii and more surface proteins in comparison with RA-TZ-containing BMPs. The TZ-containing BMPs all can be targeted to and internalized in the HER2-overexpressing breast cancer cell line SK-BR-3; however, their targeting efficiencies vary considerably: 50-75% for RA-TZ-containing BMPs and 9-19% for GA-TZ-containing BMPs. BMPs were incubated with plasma (100%) and cancer cells to simulate human in vivo environment. In this milieu, BMP-RA-TZ uptake efficiency of SK-BR-3 reaches nearly 80% (slightly lower than for direct interaction with BMP-RA-TZ), whereas the BMP-GA-TZ uptake efficiency is <17%.

CONCLUSION

Application of the RA scaffold promotes and orients the arrangement of targeting ligands and reduces the shielding effect of corona proteins. This strategy improves the targeting capability and drug delivery of NP in a simulated in vivo milieu.

High affinity protein surface binding through co-engineering of nanoparticles and proteins

Control over supramolecular recognition between proteins and nanoparticles (NPs) is of fundamental importance in therapeutic applications and sensor development. Most NP-protein binding approaches use 'tags' such as biotin or His-tags to provide high affinity; protein surface recognition provides a versatile alternative strategy. Generating high affinity NP-protein interactions is challenging however, due to dielectric screening at physiological ionic strengths. We report here the co-engineering of nanoparticles and protein to provide high affinity binding. In this strategy, 'supercharged' proteins provide enhanced interfacial electrostatic interactions with complementarily charged nanoparticles, generating high affinity complexes. Significantly, the co-engineered protein-nanoparticle assemblies feature high binding affinity even at physiologically relevant ionic strength conditions. Computational studies identify both hydrophobic and electrostatic interactions as drivers for these high affinity NP-protein complexes.

Supervised learning model predicts protein adsorption to carbon nanotubes

Engineered nanoparticles are advantageous for biotechnology applications including biomolecular sensing and delivery. However, testing compatibility and function of nanotechnologies in biological systems requires a heuristic approach, where unpredictable protein corona formation prevents their effective implementation. We develop a random forest classifier trained with mass spectrometry data to identify proteins that adsorb to nanoparticles based solely on the protein sequence (78% accuracy, 70% precision). We model proteins that populate the corona of a single-walled carbon nanotube (SWCNT)–based nanosensor and study the relationship between the protein’s amino acid–based properties and binding capacity. Protein features associated with increased likelihood of SWCNT binding include high content of solvent-exposed glycines and nonsecondary structure–associated amino acids. To evaluate its predictive power, we apply the classifier to identify proteins with high binding affinity to SWCNTs, with experimental validation. The developed classifier provides a step toward undertaking the otherwise intractable problem of predicting protein-nanoparticle interactions.

Supervised learning model predicts protein adsorption to carbon nanotubes

Engineered nanoparticles are advantageous for biotechnology applications including biomolecular sensing and delivery. However, testing compatibility and function of nanotechnologies in biological systems requires a heuristic approach, where unpredictable protein corona formation prevents their effective implementation. We develop a random forest classifier trained with mass spectrometry data to identify proteins that adsorb to nanoparticles based solely on the protein sequence (78% accuracy, 70% precision). We model proteins that populate the corona of a single-walled carbon nanotube (SWCNT)–based nanosensor and study the relationship between the protein’s amino acid–based properties and binding capacity. Protein features associated with increased likelihood of SWCNT binding include high content of solvent-exposed glycines and nonsecondary structure–associated amino acids. To evaluate its predictive power, we apply the classifier to identify proteins with high binding affinity to SWCNTs, with experimental validation. The developed classifier provides a step toward undertaking the otherwise intractable problem of predicting protein-nanoparticle interactions.

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

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

Time dependent adhesion of cells on nanorough surfaces

Understanding and controlling the mechanisms of cell adhesion to nanomaterials is essential in tissue engineering, regenerative medicine, the development of experimental models for the study of neurodegenerative diseases. Nonetheless, despite the great many of studies that have examined how cells interact with nanoscale surfaces, little is known about the temporal dimension of the process of adhesion. In a previous work, Decuzzi and Ferrari, by examining how the energy of a cell changes while binding to a nanoscale surface, determined a criterion to decide whether nanoroughness can either enhance or retard cell adhesion. While accurate, however their model template disregards the time variable. Here, starting from the work of Decuzzi and Ferrari, we have developed a mathematical model based on chemotaxis that describes how cells adhere to a nanorough surface over time. Relaxing the originating constraint of a fixed density of ligand molecules expressed by the cell membrane, we show that the strength of adhesion depends on time and that, for certain values of the model parameters, a cell can arrive to establish a stable adhesion to a substrate even if the process of binding is initially energetically unfavourable. We show that, for a cell-membrane stiffness of 10kPa, an initial density of receptors of 500bonds/μm², a specific and non-specific energy density of adhesion of 10^-5J/m² and 10^-7J/m², and roughness in the low nanometer range, cell adhesion forces can be completely activated from few seconds to some tens of minutes from the initial contact with the surface.

Titanium and Iron Oxide Nanoparticles for Cancer Therapy: Surface Chemistry and Biological Implications

Currently, cancer is among the most challenging diseases due to its ability to continuously evolve into a more complex muldimentional system, in addition to its high capability to spread to other organs and tissues. In this context, the relevance of nanobiomaterials (NBMs) for the development of new more effective and less harmful treatments is increasing. NBMs provide the possibility of combining several functionalities on a single system, expectedly in a synergic way, to better perform the treatment and cure. However, the control of properties such as colloidal stability, circulation time, pharmacokinetics, and biodistribution, assuring the concentration in specific target tissues and organs, while keeping all desired properties, tends to be dependent on subtle changes in surface chemistry. Hence, the behavior of such materials in different media/environments is of uttermost relevance and concern since it can compromise their efficiency and safety on application. Given the bright perspectives, many efforts have been focused on the development of nanomaterials fulfilling the requirements for real application. These include robust and reproducible preparation methods to avoid aggregation while preserving the interaction properties. The possible impact of nanomaterials in different forms of diagnosis and therapy has been demonstrated in the past few years, given the perspectives on how revolutionary they can be in medicine and health. Considering the high biocompatibility and suitability, this review is focused on titanium dioxide– and iron oxide–based nanoagents highlighting the current trends and main advancements in the research for cancer therapies. The effects of phenomena, such as aggregation and agglomeration, the formation of the corona layer, and how they can compromise relevant properties of nanomaterials and their potential applicability, are also addressed. In short, this review summarizes the current understanding and perspectives on such smart nanobiomaterials for diagnostics, treatment, and theranostics of diseases.

In Planta Nanosensors: Understanding Biocorona Formation for Functional Design

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

A Bottom-Up Approach to Red-Emitting Molecular-Based Nanoparticles with Natural Stealth Properties and their Use for Single-Particle Tracking Deep in Brain Tissue

Fluorescent nanoparticles dedicated to bioimaging applications should possess specific properties that have to be maintained in the aqueous, reactive, and crowded biological environment. These include chemical and photostability, small size (on the scale of subcellular structures), biocompatibility, high brightness, and good solubility. The latter is a major challenge for inorganic nanoparticles, which require surface coating to be made water soluble. Molecular-based fluorescent organic nanoparticles (FONs) may prove a promising, spontaneously water-soluble alternative, whose bottom-up design allows for the fine-tuning of individual properties. Here, the critical challenge of controlling the interaction of nanoparticles with cellular membranes is addressed. This is a report on bright, size-tunable, red-emitting, naturally stealthy FONs that do not require the use of antifouling agents to impede interactions with cellular membranes. As a proof of concept, single FONs diffusing up to 150 µm deep in brain tissue are imaged and tracked.

Engineering the Interface between Inorganic Nanoparticles and Biological Systems through Ligand Design

Nanoparticles (NPs) provide multipurpose platforms for a wide range of biological applications. These applications are enabled through molecular design of surface coverages, modulating NP interactions with biosystems. In this review, we highlight approaches to functionalize nanoparticles with "small" organic ligands (Mw < 1000), providing insight into how organic synthesis can be used to engineer NPs for nanobiology and nanomedicine.

Advances in engineering near-infrared luminescent materials

Near-infrared (NIR) luminescent materials have emerged as a growing field of interest, particularly for imaging and optics applications in biology, chemistry, and physics. However, the development of materials for this and other use cases has been hindered by a range of issues that prevents their widespread use beyond benchtop research. This review explores emerging trends in some of the most promising NIR materials and their applications. In particular, we focus on how a more comprehensive understanding of intrinsic NIR material properties might allow researchers to better leverage these traits for innovative and robust applications in biological and physical sciences.

Rapid SARS-CoV-2 Spike Protein Detection by Carbon Nanotube-Based Near-Infrared Nanosensors

To effectively track and eliminate COVID-19, it is critical to develop tools for rapid and accessible diagnosis of actively infected individuals. Here, we introduce a single-walled carbon nanotube (SWCNT)-based optical sensing approach toward this end. We construct a nanosensor based on SWCNTs noncovalently functionalized with ACE2, a host protein with high binding affinity for the SARS-CoV-2 spike protein. The presence of the SARS-CoV-2 spike protein elicits a robust, 2-fold nanosensor fluorescence increase within 90 min of spike protein exposure. We characterize the nanosensor stability and sensing mechanism and passivate the nanosensor to preserve sensing response in saliva and viral transport medium. We further demonstrate that these ACE2-SWCNT nanosensors retain sensing capacity in a surface-immobilized format, exhibiting a 73% fluorescence turn-on response within 5 s of exposure to 35 mg/L SARS-CoV-2 virus-like particles. Our data demonstrate that ACE2-SWCNT nanosensors can be developed into an optical tool for rapid SARS-CoV-2 detection.

Insights into colloidal nanoparticle-protein corona interactions for nanomedicine applications

Colloidal nanoparticles (NPs) have attracted significant attention due to their unique physicochemical properties suitable for diagnosing and treating different human diseases. Nevertheless, the successful implementation of NPs in medicine demands a proper understanding of their interactions with the different proteins found in biological fluids. Once introduced into the body, NPs are covered by a protein corona (PC) that determines the biological behavior of the NPs. The formation of the PC can eventually favor the rapid clearance of the NPs from the body before fulfilling the desired objective or lead to increased cytotoxicity. The PC nature varies as a function of the different repulsive and attractive forces that govern the NP-protein interaction and their colloidal stability. This review focuses on the phenomenon of PC formation on NPs from a physicochemical perspective, aiming to provide a general overview of this critical process. Main issues related to NP toxicity and clearance from the body as a result of protein adsorption are covered, including the most promising strategies to control PC formation and, thereby, ensure the successful application of NPs in nanomedicine.