Inorganic nanoparticles (NP), particularly gold nanoparticles, hold great promise for biomedical applications. However, one of the major challenges in the implementation of therapeutic applications based on inorganic nanoparticles is the individuation of appropriate coatings, which are indeed responsible for stability, escape from the immune system, and further functionalization. In this paper, we explore the properties of the multi-azide-containing and highly nonfouling polymer PAcrAm-g-(PMCA, NH2, ND), based on poly(oxazoline) derivatives grafted to a poly(acrylamide), as a coating for gold nanoparticles that can grant stability and easiness of derivatization and can prevent nonspecific protein adhesion on gold nanoparticles (Au-NP). We found that the addition of the polymer to citrate-stabilized gold nanoparticles led to the formation of NP suspensions with excellent colloidal stability, as confirmed by dynamic light scattering (DLS), ζ potential, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM) investigations. In addition, the AuNP coating strongly decreases the protein adsorption corona and does not activate dendritic cells (DCs), showing low immunogenicity and potentially decreasing the NP clearance by the mononuclear phagocyte system.

Abstract Human serum albumin (hSA) is the most abundant protein in human plasma, and its pharmacological properties, such as long plasma half-life mediated by the neonatal Fc receptor (FcRn) and its ability to bind endogenous and exogenous molecules, make it attractive for biotechnological applications. Currently, most wild type (WT) SAs are derived from human or bovine serum or produced in yeast and mammalian cells. Although well established, these methods are costly, difficult to reproduce, and not environmentally sustainable. Building on a previous study to design highly mutated hSA sequences, we extend the validation through an in-depth analysis of three engineered hSA variants; hSA1, hSA2, and hSA3, containing 16, 25, or 73 amino acid substitutions, respectively. These variants were designed for enhanced solubility, stability, and expression in Escherichia coli. All three variants showed low- micromolar affinities for hFcRn at pH 5.5, and negligible binding at pH 7.4. In a human endothelial cell-based recycling assay (HERA), the engineered hSA variants were recycled by hFcRn to the same extent as hSA isolated from serum. Exploring the properties of canonical drug-binding sites, warfarin affinity was comparable to WT hSA, whereas ibuprofen binding differed. Complementary cytotoxicity assays on human macrophages confirmed negligible toxicity and biocompatibility. A cryo-electron microscopy structure of hSA3 revealed that, despite extensive engineering, the native heart-shape of hSA, folding of domains, and its open conformation were preserved. These findings validate the structural integrity and functional adaptability of engineered hSA variants, underscoring their potential as versatile, animal-free solutions for next-generation therapeutics and biotechnological applications.

The structural dispersity of poly-[oligo-(ethylene glycol) methacrylate] (POEGMA) brushes critically influences the stabilization of Au nanoparticles (NPs) and their interactions with anti-PEG antibodies (APAs). Commercial oligo-(ethylene glycol) methacrylate (OEG p MA) macromonomers are intrinsically polydisperse, featuring a distribution of ethylene glycol (EG) units spanning from n = 2 to n = 15. Flash chromatography was applied to isolate OEG 8 MA with discrete length (n = 8)the most abundant species in commercial mixtures. Controlled radical polymerization of polydisperse and discrete monomer sources was subsequently applied to generate POEG p MA and POEG 8 MA, which feature heterogeneous and homogeneous structures, respectively, while displaying an overall identical composition. When used to form shells on Au NPs, uniform POEG 8 MA brushes provided enhanced colloidal stability across a wide temperature range compared to their polydisperse counterparts. While serum protein corona formation was largely determined by polymer composition, APA binding was promoted by longer OEG segments present in polydisperse POEG p MA shells, which acted as epitopes for antibody recognition. These findings highlight how controlling polymer architecture and dispersity in the design of PEG-based shells for NPs could give access to nonimmunogenic formulations. More broadly, polymer dispersity emerges as an additional tool for modulating the behavior of nanomaterials within biological systems.

Cyclic poly(2-methyl-2-oxazine) (c-PMOZI) brush shells on Au nanoparticles (NPs) exhibit enhanced stealth properties toward serum and different cell lines compared to their linear PMOZI (l-PMOZI) counterparts. While selectively recruiting immunoglobulins, c-PMOZI shells reduce overall human serum (HS) protein binding and alter the processing of complement factor 3 (C3) compared to chemically identical linear shells. Polymer cyclization significantly decreases NP uptake by nonphagocytic cells and macrophages in both complement-deficient fetal bovine serum (FBS) and complement-expressing HS, indicating ineffective functional opsonization. Even in serum-free media, c-PMOZI-coated NPs show reduced internalization by macrophages compared to l-PMOZI-coated NPs, suggesting lower opsonin-independent cell surface affinity. This study demonstrates that cyclic PMOZI suppresses interactions of NPs with proteins and cells, highlighting how control over chain topology expands the polymer chemistry toolbox for modulating the behavior of core-shell NPs within physiological environments.

Graphene oxide (GO) nanoparticles, due to their favorable water solubility, compared to graphene (GA), are a hot research topic in biomedical and pharmaceutical research. However, GO clinical translation may be complicated by its high surface/volume ratio enhancing the interaction with human blood components. In fact, GO’s bi-dimensional nature and strong negative charge may lead to severe biological effects, such as thrombogenicity and immune cell activation. This study explores the impact of further GO surface chemical modulation on major adverse effects: blood plasma coagulation and hemolysis. To this aim, we refined GO nanoparticles by fine-tuned reduction chemistry, esterification and introduction of negative or positive charges. With this approach, we were able to mitigate plasma coagulation and hemolysis at variable degrees and to identify GO derivatives with improved biocompatibility. This opens the door to the progress of graphene-based nanotheranostic applications.

Identifying the function and composition of the protein corona (i.e., the set of host proteins interacting with nanoparticles) is considered a crucial step in the development of nanoparticles for medical and pharmacological applications. Evidence suggests that host proteins can alter NP stability, biocompatibility, and pharmacokinetics features. Therefore, in this review, we provide an updated conceptual, methodological, and experimental guideline for the study of the NP protein corona. We surveyed recent literature (2009–2024) focusing on in vitro and in vivo studies. We show that several methods, including shot-gun proteomics, protein identification after in-gel digestion, and TMT proteomics, must be carefully applied and integrated to shed light on this complex phenomenon. Hence, we discuss in detail the relative protocols, highlighting the importance of the experimental conditions, ranging from the administration route to basic, but determinant, parameters like the kind of biological host fluids, the incubation times and the NP concentrations. Additionally, we propose a series of protocols that involve studying the protein corona using purified serum or plasma proteins, as well as sera depleted of specific complement proteins, to investigate the role of their deposition on the nanoparticle surface. We also explore how the role of the protein corona in inducing uptake by phagocytic cells can be examined; finally, we discuss several methodological approaches to study the effects of different coatings on the composition of the protein corona. Available data indicated that it is possible to characterize and punctually study the differential adsorption of specific proteins onto the nanoparticle surface. This allows designing NP chemical coatings features to actively guide the protein corona formation, thus improving nanotheranostic development.

α-lipoic acid is a naturally occurring compound with potent antioxidant properties that helps protect cells and tissues from oxidative stress. Its incorporation into nanoplatforms can affect factors like bioavailability, stability, reactivity, and targeted delivery. Nanoformulations of α-lipoic acid can significantly enhance its solubility and absorption, making it more bioavailable. While α-lipoic acid can be prone to degradation in its free form, encapsulation within nanoparticles ensures its stability over time, and its release in a controlled and sustained manner to the targeted tissues and cells. In addition, α-lipoic acid can be combined with other compounds, such as other antioxidants, drugs, or nanomaterials, to create synergistic effects that enhance their overall therapeutic benefits or hinder their potential cytotoxicity. This review outlines the advantages and drawbacks associated with the use of α-lipoic acid, as well as various nanotechnological approaches employed to enhance its therapeutic effectiveness, whether alone or in combination with other bioactive agents. Furthermore, it describes the engineering of α-lipoic acid to produce poly(α-lipoic acid) nanoparticles, which hold promise as an effective drug delivery system.

The complement system, professional phagocytes and other cells such as Natural killer cells and mast cells are among the important components of the innate arm of the immune system. These constituents provide an orchestrated array of defences and responses against tissue injury and foreign particles, including nano -pharmaceuticals. While interception of nanopharmaceuticals by the immune system is beneficial for immuno-modulation and treatment of phagocytic cell disorders, it is imperative to understand the multifaceted mechanisms by which nanopharmaceuticals interacts with the immune system and evaluate the subsequent balance of beneficial versus adverse reactions. An example of the latter is adverse infusion reactions to regulatory-approved nanopharmaceuticals seen in human subjects. Here, we discuss collective opinions and findings from our laboratories in mapping nanoparticle-mediated complement and leucocyte/macrophage responses.

The control of radical damage and oxidative stress, phenomena involved in a large number of human pathologies, is a major pharmaceutical and medical goal. We here show that two biocompatible formulations of Pluronic-stabilized, poly (lipoic acid)-based nanoparticles (NP) effectively antagonized the formation of radicals and reactive oxygen species (ROS). These NPs, not only intrinsically scavenged radicals in a-cellular DPPH/ABTS assays, but also inhibited the overproduction of ROS induced by tert-Butyl hydroperoxide (t-BHP) in tumor cells (HeLa), human macrophages and neonatal rat ventricular myocytes (NRVMs). NPs were captured by macrophages and cardiomyocytes much more effectively as compared to HeLa cells and non-phagocytic leukocytes, eventually undergoing intracellular disassembly. Notably, NPs decreased the mitochondrial ROS generation induced by simulated Ischemia/Reperfusion Injury (IRI) in isolated cardiomyocytes. NPs also prevented IRI-triggered cardiomyocyte necrosis, mitochondrial dysfunction, and alterations of contraction-related intracellular Ca2+ waves. Hence, NPs appear to be an effective and cardiomyocyte-selective drug to protect against damages induced by post-ischemic reperfusion.

Considering the multifaceted protective and homeostatic roles of the complement system, many consequences arise when drug carriers, and particulate pharmaceutical formulations clash with complement proteins, and trigger complement cascade. Complement activation may induce formulation destabilization, promote opsonization, and affect biological and therapeutic performance of pharmaceutical nano- and micro-particles. In some cases, complement activation is beneficial, where complement may play a role in prophylactic protection, whereas uncontrolled complement activation is deleterious, and contributes to disease progression. Accordingly, design initiatives with particulate medicines should consider complement activation properties of the end formulation within the context of administration route, dosing, systems biology, and therapeutic perspective. Here we examine current progress in mechanistic processes underlying complement activation by pre-clinical and clinical particles, identify opportunities and challenges ahead, and suggest future directions in nanomedicine-complement interface research.

Understanding the effects mediated by a set of nanoparticle (NP)-bound host biomolecules, often indicated with the umbrella term of NP corona, is essential in nanomedicine, nanopharmacology, and nanotoxicology. Among the NP-adsorbed proteome, some factors mediate cell binding, endocytosis, and clearing by macrophages and other phagocytes (opsonins), while some others display few affinities for the cell surface (dysopsonins). The functional mapping of opsonins and dysopsonins is instrumental to design long-circulating and nanotoxicologically safe next-generation nanotheranostics. In this review, we critically analyze functional data identifying specific proteins with opsonin or dysopsonin properties. Special attention is dedicated to the following: (1) the simplicity or complexity of the NP proteome and its modulation, (2) the role of specific host proteins in mediating the stealth properties of uncoated or polymer-coated NPs, and (3) the ability of the innate immune system, and, in particular, of the complement proteins, to mediate NP clearance by phagocytes. Emerging species-specific peculiarities, differentiating humans from preclinical animal models (the murine especially), are highlighted throughout this overview. The operative definition of opsonin and dysopsonin and the measurement schemes to assess their in vitro efficacy is critically re-examined. This provides a shared and unbiased approach useful for NP opsonin and dysopsonin systematic identification.

Fluorescence is a powerful tool for mapping biological events in real-time with high spatial resolution. Ultra-bright probes are needed in order to achieve high sensitivity: these probes are typically obtained by gathering a huge number of fluorophores in a single nanoparticle (NP). Unfortunately this assembly produces quenching of the fluorescence because of short-range intermolecular interactions. Here we demonstrate that rational structural modification of a well-known molecular fluorophore N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) (NBD) produces fluorophores that self-assemble in nanoparticles in the biocompatible environment without any dramatic decrease of the fluorescence quantum yield. Most importantly, the resulting NP show, in an aqueous environment, a brightness which is more than six orders of magnitude higher than the molecular component in the organic solvent. Moreover, the NP are prepared by nanoprecipitation and they are stabilized only via non-covalent interaction, they are surprisingly stable and can be observed as individual bright spots freely diffusing in solution at a concentration as low as 1 nM. The suitability of the NP as biocompatible fluorescent probes was demonstrated in the case of HeLa cells by fluorescence confocal microscopy and MTS assays.

The effect of mild hyperthermia (MHT) on nanoparticle (NP) accumulation in rat model liver metastasis and the contribution of neoplastic and non-neoplastic cells were characterized. CdSe/ZnS QD-doped poly(lactic-co-glycolic acid) (PLGA) NPs (155 ± 10 nm) were delivered via the ileocolic vein to metastatic livers 15 min after localized MW irradiation (1 min, 41 °C) or in normothermia (37 °C, NT). Quantitative analysis of tissue sections by confocal fluorescence microscopy 1 h after NP injection showed no NP tumor accumulation in NT. On the contrary, MHT increased NP association with tumor, compared to normal tissue. Counterstaining of specific markers showed that the MHT effect is due to an increased NP endocytosis not only by tumor cells, but also by hepatocytes at the growing tumor edge and, to a minor extent, by tumor-associated macrophages. High-NP capturing hepatocytes, close to the tumor, may be a relevant phenomenon in MHT-induced increased targeting of NPs to liver metastasis, influencing their therapeutic efficacy.

Poly(2-methyl-2-oxazoline) (PMOXA) is an alternative promising polymer to poly(ethylene glycol) (PEG) for design and engineering of macrophage-evading nanoparticles (NPs). Although PMOXA-engineered NPs have shown comparable pharmacokinetics and in vivo performance to PEGylated stealth NPs in the murine model, its interaction with elements of the human innate immune system has not been studied. From a translational angle, we studied the interaction of fully characterized PMOXA-coated vinyltriethoxysilane-derived organically modified silica NPs (PMOXA-coated NPs) of approximately 100 nm in diameter with human complement system, blood leukocytes, and macrophages and compared their performance with PEGylated and uncoated NP counterparts. Through detailed immunological and proteomic profiling, we show that PMOXA-coated NPs extensively trigger complement activation in human sera exclusively through the classical pathway. Complement activation is initiated by the sensing molecule C1q, where C1q binds with high affinity ( Kd = 11 ± 1 nM) to NP surfaces independent of immunoglobulin binding. C1q-mediated complement activation accelerates PMOXA opsonization with the third complement protein (C3) through the amplification loop of the alternative pathway. This promoted NP recognition by human blood leukocytes and monocyte-derived macrophages. The macrophage capture of PMOXA-coated NPs correlates with sera donor variability in complement activation and opsonization but not with other major corona proteins, including clusterin and a wide range of apolipoproteins. In contrast to these observations, PMOXA-coated NPs poorly activated the murine complement system and were marginally recognized by mouse macrophages. These studies provide important insights into compatibility of engineered NPs with elements of the human innate immune system for translational steps.

Some hybrid foldamers of various length, all containing the (4R,5S)-4-carboxy-5-methyloxazolidin-2-one (d-Oxd) moiety alternating with an l-amino acid (l-Val, l-Lys, or l-Ala), were prepared in order to study their preferred conformations and to evaluate their biological activity. Surprisingly, only the longer oligomers containing l-Ala fold into well-established helices, whereas all the other oligomers give partially unfolded turn structures. Nevertheless, they all show good biocompatibility, with no detrimental effects up to 64 μm. After equipping some selected foldamers with the fluorescent tag rhodamine B, a quantitative analysis was performed by dose- and time-response fluorescence-activated cell sorting (FACS) assays with human HeLa cells and primary blood lymphocytes, granulocytes, and monocytes. Among the cell types analyzed, the oligomers associated with monocytes and granulocytes with greatest efficacy, still visible after 24 h incubation. This effect is even more pronounced for foldamers that are able to form stable helices.

ABSTRACT Dendritic cells (DCs) regulate the host-microbe balance in the gut and skin, tissues likely exposed to nanoparticles (NPs) present in drugs, food, and cosmetics. We analyzed the viability and the activation of DCs incubated with extracellular media (EMs) obtained from cultures of commensal bacteria ( Escherichia coli , Staphylococcus epidermidis ) or pathogenic bacteria ( Pseudomonas aeruginosa , Staphylococcus aureus ) in the presence of amorphous silica nanoparticles (SiO 2 NPs). EMs and NPs synergistically increased the levels of cytotoxicity and cytokine production, with different nanoparticle dose-response characteristics being found, depending on the bacterial species. E. coli and S. epidermidis EMs plus NPs at nontoxic doses stimulated the secretion of interleukin-1β (IL-1β), IL-12, IL-10, and IL-6, while E. coli and S. epidermidis EMs plus NPs at toxic doses stimulated the secretion of gamma interferon (IFN-γ), tumor necrosis factor alpha (TNF-α), IL-4, and IL-5. On the contrary, S. aureus and P. aeruginosa EMs induced cytokines only when they were combined with NPs at toxic concentrations. The induction of maturation markers (CD86, CD80, CD83, intercellular adhesion molecule 1, and major histocompatibility complex class II) by commensal bacteria but not by pathogenic ones was improved in the presence of noncytotoxic SiO 2 NP doses. DCs consistently supported the proliferation and differentiation of CD4 + and CD8 + T cells secreting IFN-γ and IL-17A. The synergistic induction of CD86 was due to nonprotein molecules present in the EMs from all bacteria tested. At variance with this finding, the synergistic induction of IL-1β was prevalently mediated by proteins in the case of E. coli EMs and by nonproteins in the case of S. epidermidis EMs. A bacterial costimulus did not act on DCs after adsorption on SiO 2 NPs but rather acted as an independent agonist. The inflammatory and immune actions of DCs stimulated by commensal bacterial agonists might be altered by the simultaneous exposure to engineered or environmental NPs.