Upon exposure to human blood, nanoengineered particles interact with a multitude of plasma components, resulting in the formation of a biomolecular corona. This corona modulates downstream biological responses, including recognition by and association with human immune cells. Considerable research effort has been directed toward the design of materials that can demonstrate a low affinity for various proteins (low-fouling materials) and materials that can exhibit low association with human immune cells (stealth materials). An implicit assumption common to bio–nano research is that nanoengineered particles that are low-fouling will also exhibit stealth. Herein, we investigated the link between the low-fouling properties of a particle and its propensity for stealth in whole human blood. High-fouling mesoporous silica (MS) particles and low-fouling zwitterionic poly­(2-methacryloyloxyethyl phosphorylcholine) (PMPC) particles were synthesized, and their interaction with blood components was assessed before and after precoating with serum albumin, immunoglobulin G, or complement protein C1q. We performed an in-depth proteomics characterization of the biomolecular corona that both identifies specific proteins and measures their relative abundance. This was compared with observations from a whole blood association assay that identified with which cell type each particle system associates. PMPC-based particles displayed reduced association both with cells and with serum proteins compared with MS-based particles. Furthermore, the enrichment of specific proteins within the biomolecular corona was found to correlate with association with specific cell types. This study demonstrates how the low-fouling properties of a material are indicative of its stealth with respect to immune cell association.

Water is a unique solvent that is ubiquitous in biology and present in a variety of solutions, mixtures, and materials settings. It therefore forms the basis for all molecular dynamics simulations of biological phenomena, as well as for many chemical, industrial, and materials investigations. Over the years, many water models have been developed, and it remains a challenge to find a single water model that accurately reproduces all experimental properties of water simultaneously. Here, we report a comprehensive comparison of structural and dynamic properties of 30 commonly used 3-point, 4-point, 5-point, and polarizable water models simulated using consistent settings and analysis methods. For the properties of density, coordination number, surface tension, dielectric constant, self-diffusion coefficient, and solvation free energy of methane, models published within the past two decades consistently show better agreement with experimental values compared to models published earlier, albeit with some notable exceptions. However, no single model reproduced all experimental values exactly, highlighting the need to carefully choose a water model for a particular study, depending on the phenomena of interest. Finally, machine learning algorithms quantified the relationship between the water model force field parameters and the resulting bulk properties, providing insight into the parameter−property relationship and illustrating the challenges of developing a water model that can accurately reproduce all properties of water simultaneously.

In biological fluids, proteins bind to particles, forming so-called protein coronas. Such adsorbed protein layers significantly influence the biological interactions of particles, both in vitro and in vivo. The adsorbed protein layer is generally described as a two-component system comprising "hard" and "soft" protein coronas. However, a comprehensive picture regarding protein corona structure is lacking. Herein, we introduce an experimental approach that allows for in situ monitoring of protein adsorption onto silica microparticles. The technique, which mimics flow in vascularized tumors, combines confocal laser scanning microscopy with microfluidics and allows the study of the time-evolution of protein corona formation. Our results show that protein corona formation is kinetically divided into three different phases: phase 1, proteins irreversibly and directly bound (under physiologically relevant conditions) to the particle surface; phase 2, irreversibly bound proteins interacting with pre-adsorbed proteins, and phase 3, reversibly bound "soft" protein corona proteins. Additionally, we investigate particle-protein interactions on lowfouling zwitterionic-coated particles where the adsorption of irreversibly bound proteins does not occur, and on such particles only a "soft" protein corona is formed. The reported approach offers the potential to define new state-of-the art procedures for kinetics and protein fouling experiments. 9 Depending on the characterization method used, the protein corona is described according to either the Gibbs free energy ΔG, 8,10-12 which defines the adsorption and desorption rates of proteins, or binding force 13,14 between the proteins and particle surface. Proteins with a large ΔG have a low probability of desorption and therefore remain associated with the particle surface. These proteins are considered to form the "hard" protein corona. Distinction based on binding forces implies that "hard" protein corona proteins interact directly with the particle surface through long-range, strong protein-surface interactions, whereas proteins in the "soft" protein corona interact with other proteins through short-range, weak protein-protein interactions. Another theoretical distinction is based on the persistence of the protein to remain adsorbed throughout the nanoparticle's journey (i.e. from bloodstream to tissue and past-endocytic environments) as protein corona composition changes during biophysical events. 6-8,15,16 The concept of "persistent" proteins 5 originates from studies where the "hard" protein corona is used to follow the particle's past. 17-19 It is becoming increasingly important to clearly understand the complex process of protein corona formation, with a focus on the influence of the "soft" protein corona on physiological interactions. 4,7,13,20-24 However, to do so, it is crucial to acquire and understand further details such as the time-evolution of protein corona formation. Existing techniques for investigating the protein corona can be divided into ex situ and in situ ...

The adsorption of biomolecules onto nanomaterials can alter the performance of the nanomaterials in vitro and in vivo. Recent studies have primarily focused on the protein "corona", formed upon adsorption of proteins onto nanoparticles in biological fluids, which can change the biological fate of the nanoparticles. Conversely, interactions between nanomaterials and other classes of bio molecules namely, lipids, nucleic acids, and polysaccharides have received less attention despite their important roles in biology.A possible reason is the challenge associated with investigating biomolecule interactions with nanomaterials using current technologies. Herein, a protocol is developed for studying bio-nano interactions by depositing four classes of biomolecules (proteins, lipids, nucleic acids, and polysaccharides) and complex biological media (blood) onto planar substrates, followed by exposure to metal-phenolic network (MPN) complexes. The MPNs preferentially interact with the bio molecule over the inorganic substrate (glass), highlighting that patterned bio molecules can be used to engineer patterned MPNs. Subsequent formation of silver nanoparticles on the MPN films maintains the patterns and endows the films with unique reflectance and fluorescence properties, enabling visualiza tion of latent fingerprints (i.e., invisible residual biomolecule patterns). This study demonstrates the potential complexity of the biomolecule corona as all classes of biomolecules can adsorb onto MPNbased nanomaterials.