Protein Adsorption Process Research Articles

Comparison of the Adsorption and Desorption Dynamics of Biological Molecules on Alginate Hydrogel Microcapsules-The Case of Sugars, Polyphenols, and Proteins.

The aim of this work was to analyze and compare the adsorption and desorption processes of carbohydrates (glucose as a model molecule), polyphenols (gallic acid as a model molecule), and proteins (bovine serum albumin, BSA as a model molecule) on alginate microcapsules. The adsorption and desorption processes were described by mathematical models (pseudo-first-order, pseudo-second-order, and Weber-Morris intraparticle diffusion model for adsorption, and first-order, Korsmeyer-Peppas, and the Higuchi model for desorption) in order to determine the dominant mechanisms responsible for both processes. By comparing the values of adsorption rate (k2) and initial adsorption rate (h0) based on the pseudo-first-order model, the lowest values were recorded for BSA (k1 = 0.124 ± 0.030 min-1), followed by glucose (k1 = 0.203 ± 0.041 min-1), while the model-obtained values for gallic acid were not considered significant at p < 0.05. For glucose and gallic acid, the limiting step of the adsorption process is the chemical sorption of substances, and the rate of adsorption does not depend on the adsorbate concentration, but depends on the capacity of the hydrogel adsorbent. Based on the desorption rates determined by the Korsmeyer-Peppas model (k), the highest values were recorded for gallic acid (k = 3.66236 ± 0.20776 g beads/mg gallic acid per min), followed by glucose (k = 2.55760 ± 0.16960 g beads/mg glucose per min) and BSA (k = 0.78881 ± 0.11872 g beads/mg BSA per min). The desorption process from alginate hydrogel microcapsules is characterized by the pseudo Fickian diffusion mechanism.

Citrate coated iron oxide nanoparticles: Synthesis, characterization, and performance in protein adsorption

&lt;p&gt;Magnetic nanoparticles (MNPs) are extensively utilized in biomedicine as part of controlled drug release systems, hyperthermia, and magnetic resonance imaging. Surface modification of MNPs not only enhances their stability and biocompatibility but also increases affinity with certain molecules, allowing them to be used in protein separation and adsorption processes. This article reports the synthesis and characterization of iron oxide MNPs functionalized with citric acid (IONPs@CA) to evaluate their performance in protein adsorption. The nanoparticles were characterized using various techniques such as transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic light scattering (DLS), thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FT-IR). The percentage of lysozyme (Lyz) adsorbed by IONPs@CA was 84.9%, while the IONPs sample only adsorbed 5.9%. In silico evaluation results showed some repulsion bonds obtained in Lyz-IONPs and hydrogen bonds, carbon-hydrogen bonds, and van der Waals interactions in Lyz-IONPs@CA. These results may be novel since no previous research was found specifying this type of interaction between lysozyme and IONPs and/or IONPs@CA. The maximum adsorption efficiency obtained for the coated nanoparticles was 88.3%.&lt;/p&gt;

Adsorption of Heparin-Binding Fragments of Fibronectin onto Hydrophobic Surfaces

Fibronectin is a multi-domain, extracellular matrix protein that plays a number of biological roles. As the adsorption of fibronectin onto the surface of implanted devices can lead to an inflammatory response or bacterial colonisation, understanding the interaction of fibronectin with material surfaces is important in the design of materials for biomedical applications. This, however, relies on having knowledge of the molecular-scale behaviour of proteins, which is difficult to investigate experimentally. In this paper, we used molecular dynamics simulations to investigate the adsorption of heparin-binding fibronectin domains onto hydrophobic surfaces. Despite the high similarity between these, their adsorption differs both in terms of the strength and the specificity of this, indicating that relatively small changes in protein structure can lead to significant changes in adsorption behaviour. This suggests that the interplay between protein structure and surface chemistry is vital for understanding the protein adsorption process and the design of novel biomaterials.

Graphic contrastive learning analyses of discontinuous molecular dynamics simulations: Study of protein folding upon adsorption

A comprehensive understanding of the interfacial behaviors of biomolecules holds great significance in the development of biomaterials and biosensing technologies. In this work, we used discontinuous molecular dynamics (DMD) simulations and graphic contrastive learning analysis to study the adsorption of ubiquitin protein on a graphene surface. Our high-throughput DMD simulations can explore the whole protein adsorption process including the protein structural evolution with sufficient accuracy. Contrastive learning was employed to train a protein contact map feature extractor aiming at generating contact map feature vectors. Subsequently, these features were grouped using the k-means clustering algorithm to identify the protein structural transition stages throughout the adsorption process. The machine learning analysis can illustrate the dynamics of protein structural changes, including the pathway and the rate-limiting step. Our study indicated that the protein–graphene surface hydrophobic interactions and the π–π stacking were crucial to the seven-stage adsorption process. Upon adsorption, the secondary structure and tertiary structure of ubiquitin disintegrated. The unfolding stages obtained by contrastive learning-based algorithm were not only consistent with the detailed analyses of protein structures but also provided more hidden information about the transition states and pathway of protein adsorption process and structural dynamics. Our combination of efficient DMD simulations and machine learning analysis could be a valuable approach to studying the interfacial behaviors of biomolecules.

Influence of clinical hemodialysis membrane morphology and chemistry on protein adsorption and inflammatory biomarkers released: In-situ synchrotron imaging, clinical and computational studies

Hemodialysis (HD) is often accompanied with activation of biochemical cascade reactions, caused by undesirable protein adsorption, which results in severe consequences for HD patients. Present research aims to study three hemodialysis membranes currently available in the Canadian hospitals of polyacrylonitrile (PAN), polyethersulfone (PES) and polyvinylidene fluoride (PVDF) and their interaction with three main human serum proteins: Human Serum Ablumin (HSA), Human Serum Fibrinogen (FB) and Human Serum Transferrin (TRF). In-situ synchrotron-based X-ray tomography (SR-μCT) was used to evaluate main membranes characteristics such as fiber diameter, pore size and their distribution, as well as to study the process of protein adsorption on the membranes surface and along membrane matrices. Scanning Electron Microscopy (SEM) was also used to investigate the morphology of proteins deposited on the membrane surface. Furthermore, interaction of membranes with inflammatory biomarkers was studied. Collected blood samples from HD patients were analyzed using Luminex assay for the inflammatory biomarkers of Serpin/Antitrombin-III, Properdin, C5a, 1L-1α, 1L-1β, IL-6 and TNF-α. Our results indicate the difference in the interaction of membranes with proteins is mainly attributed to a membrane surface charge and membrane chemistry. PAN and PES membranes, which are possessing high negative charge (-41.5mV and -68mV) and polar surface groups, would alter the morphology of adsorbed HAS and FB, while PVDF surface does not affect protein crystals growth. Furthermore, the molecular docking results showed that the highest interaction energy of human serum proteins was with PES membrane. The increased interaction of PES membrane with human serum proteins has triggered inflammation reactions. The release of C5a, IL-6 and Serpin cytokines for PES membrane was drastically higher compared to PAN and PVDF. The relative increase in those cytokine concentrations was 400-2000% for PES membrane, while it decreased by 10-40% for PAN and PVDF. It is worth noted that PVDF membrane had the lowest charge of -2.5 mV among investigated membranes, and it possessed the lowest interaction with human serum proteins and the least inflammation response.

Thin Films of Lanthanide Stearates as Modifiers of the Q-Sense Device Sensor for Studying Insulin Adsorption.

This article presents new possibilities of using thin films of lanthanide stearates as sorbent materials. Modification of the Q-sense device resonator with monolayers of lanthanide stearates by the Langmuir–Schaeffer method made it possible to study the process of insulin protein adsorption on the surface of new thin-film sorbents. The resulting films were also characterized by compression isotherms, chemical analysis, scanning electron microscopy, and mass spectrometry. The transition of stearic acid to salt was recorded by IR spectroscopy. Using the LDI MS method, the main component of thin films, lanthanide distearate, was established. The presence of Eu2+ in thin films was revealed. In the case of europium stearate, the maximum value of insulin adsorption was obtained, −1.67·10−10 mole/cm2. The findings suggest the possibility of using thin films of lanthanide stearates as a sorption material for the proteomics determination of the quantitative protein content in complex fluid systems by specific adsorption on modified surfaces and isolation of such proteins from complex mixtures.

Proteins Adsorbing onto Surface-Modified Nanoparticles: Effect of Surface Curvature, pH, and the Interplay of Polymers and Proteins Acid-Base Equilibrium.

Protein adsorption onto nanomaterials is a process of vital significance and it is commonly controlled by functionalizing their surface with polymers. The efficiency of this strategy depends on the design parameters of the nanoconstruct. Although significant amount of work has been carried out on planar surfaces modified with different types of polymers, studies investigating the role of surface curvature are not as abundant. Here, we present a comprehensive and systematic study of the protein adsorption process, analyzing the effect of curvature and morphology, the grafting of polymer mixtures, the type of monomer (neutral, acidic, basic), the proteins in solution, and the conditions of the solution. The theoretical approach we employed is based on a molecular theory that allows to explicitly consider the acid–base reactions of the amino acids in the proteins and the monomers on the surface. The calculations showed that surface curvature modulates the molecular organization in space, but key variables are the bulk pH and salt concentration (in the millimolar range). When grafting the NP with acidic or basic polymers, the surface coating could disfavor or promote adsorption, depending on the solution’s conditions. When NPs are in contact with protein mixtures in solution, a nontrivial competitive adsorption process is observed. The calculations reflect the balance between molecular organization and chemical state of polymers and proteins, and how it is modulated by the curvature of the underlying surface.

An efficient way to change surface properties of poly(l-lactic acid) by synthesis of polycaprolactone grafted fluoropolyacrylate

Macromolecules with fluoroalkyl group are promising as anti-fouling materials. In the work, a series of polycaprolactone grafted poly(octafluoropentyl methacrylate-co-hydroxyethyl methacrylate)s (PCL-PFHs) were synthesized as additives to change the surface properties of poly(l-lactic acid) (PLLA). The synthesized products were characterized with 1HNMR and GPC. PCL-PFH and PLLA were immiscible in blend, but PCL-PFH microparticles could immerse uniformly in PLLA substrate. The molar ratio of [OFPA]/[HEMA] in PFH and blend ratio of PCL-PFH/PLLA played a key role in changing the surface properties of PLLA blend. When the molar ratio and blend ratio were 4/1 and 10/90 respectively, the surface tension of PLLA blend lowered to 19.57 mN m−1, and it inhibited BSA adhesion effectively during protein adsorption process. At the same time, PLLA blend presented good hydrolytic stability. PCL-PFH also toughened PLLA, and the tensile strength and elongation at a break were 37.0 MPa and 126.1%. Then this work would built a new bridge between PLLA materials and biomedical engineering.

Probing the Bovine Hemoglobin Adsorption Process and its Influence on Interfacial Water Structure at the Air-Water Interface.

*These authors contributed equally to this work.The molecular-level insight of protein adsorption and its kinetics at interfaces is crucial because of its multifold role in diverse fundamental biological processes and applications. In the present study, the sum frequency generation (SFG) vibrational spectroscopy has been employed to demonstrate the adsorption process of bovine hemoglobin (BHb) protein molecules at the air-water interface at interfacial isoelectric point of the protein. It has been observed that surface coverage of BHb molecules significantly influences the arrangement of the protein molecules at the interface. The time-dependent SFG studies at two different frequencies in the fingerprint region elucidate the kinetics of protein denaturation process and its influence on the hydrogen-bonding network of interfacial water molecules at the air-water interface. The initial growth kinetics suggests the synchronized behavior of protein adsorption process with the structural changes in the interfacial water molecules. Interestingly, both the events carry similar characteristic time constants. However, the conformational changes in the protein structure due to the denaturation process stay for a long time, whereas the changes in water structure reconcile quickly. It is revealed that the protein denaturation process is followed by the advent of strongly hydrogen-bonded water molecules at the interface. In addition, we have also carried out the surface tension kinetics measurements to complement the findings of our SFG spectroscopic results.

Computational fluid dynamics simulation of adsorption process in a liquid-solids fluidized bed

For simultaneously predicting the hydrodynamics and protein adsorption process in a liquid-solids fluidized bed (LSFB), a computational fluid dynamics (CFD) model is established by combining the two-fluid model (TFM) for the liquid-particles two-phase fluidization system with the c2¯−εc model for the turbulent mass transfer. In terms of hydrodynamics, the kl−εl−kp−εp−Θ equations are adopted to describe phases turbulence. The simulations of hydrodynamics using various drag models and different modelling parameters are conducted to test their sensitivity. Then for the adsorption process, the recently developed formulations of the c2¯−εc model are adopted to characterize rigorously the turbulent mass diffusion in LSFB. With the proposed model, the velocity field as well as the concentration field can be acquired. Simulated results are compared with the experimental data and a good agreement between them is found.

Surface Chemistry, Crystal Structure, Size and Topography Role in the Albumin Adsorption Process on TiO2 Anatase Crystallographic Faces and Its 3D-Nanocrystal: A Molecular Dynamics Study

TiO2 is widely used in biomaterial implants. The topography, chemical and structural properties of titania surfaces are an important aspect to study. The size of TiO2 nanoparticles synthetized by sol–gel method can influence the responses in the biological environment, and by using appropriate heat treatments different contents of different polymorphs can be formed. Protein adsorption is a crucial step for the biological responses, involving, in particular, albumin, the most abundant blood protein. In this theoretical work, using molecular mechanics and molecular dynamics methods, the adsorption process of an albumin subdomain is reported both onto specific different crystallographic faces of TiO2 anatase and also on its ideal three-dimensional nanosized crystal, using the simulation protocol proposed in my previous theoretical studies about the adsorption process on hydrophobic ordered graphene-like or hydrophilic amorphous polymeric surfaces. The different surface chemistry of anatase crystalline faces and the nanocrystal topography influence the adsorption process, in particular the interaction strength and protein fragment conformation, then its biological activity. This theoretical study can be a useful tool to better understand how the surface chemistry, crystal structure, size and topography play a key role in protein adsorption process onto anatase surface so widely used as biomaterial.

Analysis of binding modes of biopanning heptapeptides with specific affinity to chitosan wrapped MSN

In this work, we demonstrated for the first time that six short heptapeptides screened out by biopanning strategy show affinity binding to chitosan wrapped mesoporous silica nanoparticle (CS/MSN). The interaction between peptide and chitosan-wrapped MSN (CS/MSN) was carefully analyzed with the aid of DLS and ELISA characterization. The results show that π-π stacking and hydrogen bonds account for the strong adsorption under neutral as well as acidic conditions. While hydrophilic and electrostatic interaction are the major modes of the peptide under alkaline condition. These different interaction modes involved in the adsorption of peptides onto CS/MSN could vividly mimic the binding of peptide with chitosan in physiological conditions and help to deeply understand the process of protein adsorption on nanomaterials.

Modeling study of adsorption/desorption of proteins by polymer mixed brush

Based on the diffusion dynamics, a new theoretical model is established to investigate the dynamic properties of a polymer mixed brush (PMB) in the protein adsorption/desorption process. The theoretical model considers the adsorption of proteins by one polymer chain (P-polymer chain) and the desorption of proteins by another polymer chain (N-polymer chain) in a PMB, as well as the time delay between adsorption and desorption. The dynamic properties of protein adsorption/desorption by a PMB depend on not only the chemical and physical properties of polymer chains, but also the microenvironment (density of protein in the solution and protein diffusivity) of the PMB. In order to describe the different chemical and physical properties of polymer chains and microenvironments in PMB, we take different model parameters, and obtain partial adsorption/desorption, complete adsorption/desorption and periodic adsorption/desorption of proteins by the PMB. By analyzing the process of protein adsorption/desorption in a PMB, we find that the microenvironment has an obvious influence on the adsorption and desorption of protein by the PMB. It is also shown that the adsorption of protein and the desorption of protein by the PMB have a stable and invariable periodic cycle when an alternating electric field is applied. The average adsorption capacity and the average desorption capacity increase in comparison with those when no electric field is applied. A stable alternating electric field enables the PMB to exhibit stable periodic dynamic characteristics in the dynamic process of protein adsorption and desorption. Our theoretical results are consistent with the experimental observations. Based on this, it is predicted that an external electric field can realize multiple cycles of protein adsorption and desorption by PMB, which provides necessary references and useful insights into controllable protein adsorption/desorption by the PMB in the practical applications.

Role of phosphate, calcium species and hydrogen peroxide on albumin protein adsorption on surface oxide of Ti6Al4V alloy

Protein adsorption and its conformational arrangements on the surface of metallic biomaterials directly influence the biocompatibility and the degradation process during the implant lifetime. However, the presence of various species such as phosphates, calcium and hydrogen peroxide (H2O2) in the human body not only control the electrochemical interactions on the biomaterial surface but could also modify the protein adsorption process and its impact on the metal degradation. To this aim bovine serum albumin (BSA) protein adsorption, morphology, surface potential and its impact on the corrosion resistance of a Ti6Al4V alloy was investigated in different solutions, including a sodium chloride (NaCl), a phosphate-buffered saline (PBS) and Hank's physiological solutions. The results indicated that the alloy in PBS solution was more resistant to corrosion than that in Hanks’ or NaCl solutions. Mott–Schottky analysis demonstrated that all solutions containing BSA and H2O2 had the highest donor charge carrier. Scanning electron microscopy (SEM) and surface potential images indicated that by changing the physiological solutions from NaCl to PBS and then to Hanks’, the morphology of adsorbed BSA protein changed from a globular or unfolded shape to a large micronetwork and then to a fine micro-nanonetwork, accompanied by a gradual increase in the surface potential. Moreover, it was figured out that the BSA protein/substrate interface and the top surface of the BSA protein were susceptible to corrosion initiation owing to the different surface potentials and thus are preferable sites for the adsorption of corrosive counterions, e.g., Cl−.

Silica-supported carboxylated cellulose nanofibers for effective lysozyme adsorption: Effect of macropore size

Engineering hierarchical macro/mesoporous structures that offer an abundance of accessible binding sites are highly desirable in protein adsorption processes. However, numerous significant challenges remain. Herein, cellulose nanofiber (CNF)-loaded macroporous silica (CNF-MPS) particles were successfully synthesized with a high degree of accessible binding sites by tuning the macropore size of the silica particles and loading a highly carboxylated CNF via smart and rational design. The as-prepared CNF-MPS particles exhibited a high negative charge (~−59 mV) and excellent protein adsorption ability (>1000 mg/g) in <5 min. Furthermore, tuning the macropore size influenced the CNF deposition either to the external surface or penetrating within the pores. As a result, the optimum macropore successfully enhances the adsorption capability to >1500 mg/g as a result of improved interconnectivity between the channels. Here exposed macropores of >100 nm allows ingress of protein to the interior structure that houses an abundance of binding sites comprising the dispersed CNF. Additionally, the adsorption kinetics, thermodynamics, and isothermal parameters were studied to analyze the mechanism of lysozyme adsorption. The adsorption process is confirmed to occur spontaneously at any temperature with a pseudo-second-order model describing the kinetic model, and CNF deposition affecting the heterogeneity of the binding sites.

Differences in corona formation of catalase immobilised on gold and silver nanoparticles

The adsorption process of proteins on nanoparticles (NPs) is spontaneous and depends on many factors, including the NP composition, size, shape, dispersity, and surface chemistry, as well the protein type, its chemical structure, affinity to NP surface, size, shape, availability of functional groups, etc. As a result, prediction of the adsorption process and the surface coverage of NPs with proteins remains a challenge. The theoretical coverage can obviously be calculated on the basis of geometric considerations, assuming that proteins remain globular on the NP surface; however, this is only a model approach, which does not always coincide with experimental results. Hence, experimental techniques are needed to characterise bioconjugates and to determine how many protein molecules bind to a NP surface.In this paper, we quantitatively characterise the surface coverage of NPs with catalase on the basis of polyacrylamide gel electrophoresis (PAGE). The surface coverage was investigated on two types of metallic NPs with a diameter equal 13 nm: i) gold and ii) silver. The obtained results prove that the protein corona formation significantly depends on the chemical composition of NPs and is difficult to predict how many protein molecules have to be incorporated into the colloid to attain assumed surface coverage.

Recent advances towards single biomolecule level understanding of protein adsorption phenomena unique to nanoscale polymer surfaces with chemical variations

Protein adsorption onto polymer surfaces is a very complex and ubiquitous phenomenon whose integrated process impacts essential applications in our daily lives such as food packaging materials, health devices, diagnostic tools, and medical products. Increasingly, novel polymer materials with greater chemical intricacy and reduced dimensionality are used for various applications involving adsorbed proteins on their surfaces. Hence, the nature of protein-surface interactions to consider is becoming much more complicated than before. A large body of literature exists for protein adsorption. However, most of these investigations have focused on collectively measured, ensemble-averaged protein behaviors that occur on macroscale and chemically unvarying polymer surfaces instead of direct measurements at the single protein or sub-protein level. In addition, interrogations of protein-polymer adsorption boundaries in these studies were typically carried out by indirect methods, whose insights may not be suitably applied for explaining individual protein adsorption processes occurring onto nanostructured, chemically varying polymer surfaces. Therefore, an important gap in our knowledge still exists that needs to be systematically addressed via direct measurement means at the single protein and sub-protein level. Such efforts will require multifaceted experimental and theoretical approaches that can probe multilength scales of protein adsorption, while encompassing both single proteins and their collective ensemble behaviors at the length scale spanning from the nanoscopic all the way to the macroscopic scale. In this review, key research achievements in nanoscale protein adsorption to date will be summarized. Specifically, protein adsorption studies involving polymer surfaces with their defining feature dimensions and associated chemical partitions comparable to the size of individual proteins will be discussed in detail. In this regard, recent works bridging the crucial knowledge gap in protein adsorption will be highlighted. New findings of intriguing protein surface assembly behaviors and adsorption kinetics unique to nanoscale polymer templates will be covered. Single protein and sub-protein level approaches to reveal unique nanoscale protein-polymer surface interactions and protein surface assembly characteristics will be also emphasized. Potential advantages of these research endeavors in laying out fundamentally guided design principles for practical product development will then be discussed. Lastly, important research areas still needed to further narrow the knowledge gap in nanoscale protein adsorption will be identified.

Influence of Structured Water Layers on Protein Adsorption Process: A Case Study of Cytochrome c and Carbon Nanotube Interactions and Its Implications.

Cytochrome c, an essential protein of the electron transport chain, is known to be capable of amplifying the toxicity of carbon nanomaterials via free-radical generation. To understand their interaction, as well as the more general protein-nanoparticle interaction at molecular levels, we investigate the adsorptions between cytochrome c and carbon nanotubes (CNTs) in dynamic and thermodynamic ways using molecular dynamics simulations. The results reveal a well-defined three-phase process separated by two transition points: the diffusion phase where the protein diffuses in the water box, the lockdown phase I where the protein inserts into the surface-bound water layers and rearranges its conformation to fit to the surface of the CNT, and the lockdown phase II where cytochrome c repels the water molecules standing in its way to the surface of CNT and reaches stable adsorption states. The structured water layers affect the movement of atoms by electrostatic forces. In lockdown phase I, the conformation adjustment of the protein dominates the adsorption process. The most thermally favorable adsorption conformation is determined. It shows that except for the deformation of short β sheets and some portions of α helixes, most of the secondary structures of cytochrome c remain unchanged, implying that most of the functions of cytochrome c are preserved. During these processes, the energy contributions of the hydrophilic residues of cytochrome c are much larger than those of hydrophobic residues. Interestingly, the structured water layers at the CNT surface allow more hydrophilic residues such as Lys to get into close contact with the CNT, which plays a significant role during the anchoring process of adsorption. Our results demonstrate that the heme group is in close contact with the CNT in some of the adsorbed states, which hence provides a way for electron transfer from cytochrome c to the CNT surface.

Integrated approach in designing biphasic nanocomposite collagen/nBCP scaffolds with controlled porosity and permeability for bone tissue engineering.

The bone scaffold for tissue engineering should be biomimetic, particularly in simulating the porosity features of natural bony tissue including pore size, pore shape, pore distribution pattern, and porosity percentage. Control of these can impact the scaffold hydrophilicity and permeability, which in turn influence the protein adsorption, cellular functions, and vascularization process. Various methods have been investigated for control of porosity parameters; however, the field still suffers from major challenges, that is, inadequate control of porosity and hydrophilicity at different levels. In this study, we developed an integrated approach for generation and control of porosity within nanocomposite collagen/nanobiphasic calcium phosphate (collagen/nBCP) scaffold. A modified freeze-drying procedure was applied alongside a chemical foaming method exploring the ability of "Tween 20" as a potent biocompatible porogen. Several processing variables were also examined including; quenching rate (-18 and -80°C), collagen/nBCP ratio (92/8% and 85/15%), and Tween ratio (10%, 20%, and 30%). Detailed physicochemical and porosimetry analysis confirmed the ability of Tween to actively modify the scaffold permeability and pore size by increasing the range of pore size while quenching rate mostly influenced the pore shape, and collagen/nBCP ratio affected total porosity and roughness. The collagen/nBCP ratio of 92/8% treated with low Tween ratios (10% and 20%) and exposed to -80°C quenching rate displayed more favorable physicochemical behavior, significantly higher permeability, a gradient porosity, and better in vitro performances. The proposed technique in this study provides an insight into the production of customized scaffolds for various tissue engineering applications.

Sulfidation of Ag and ZnO Nanomaterials Significantly Affects Protein Corona Composition: Implications for Human Exposure to Environmentally Aged Nanomaterials.

The physicochemical properties of engineered nanomaterials can change drastically during aging in the environment. Understanding how these changes influence protein corona formation on nanomaterials is critical for accurately predicting the human exposure risks of aged nanomaterials. Here, we show that sulfidation, a prevalently occurring environmental aging process, of Ag and ZnO nanomaterials significantly affected the protein compositions of the hard corona formed in human saliva, sweat, and bronchoalveolar lavage fluid, corresponding to three most common exposure pathways, that is, ingestion, dermal contact, and inhalation. In particular, a diverse variety of proteins selectively associated with either sulfidized or pristine nanomaterials. Random forest classification of the proteomic data revealed that this selective protein adsorption process was mainly dictated by electrostatic interaction, hydrophobic interaction, and steric hindrance between proteins and nanomaterials, which were susceptible to the changes in surface charge, hydrophobicity, and aggregation status of nanomaterials induced by sulfidation. Furthermore, even for the proteins that do not exhibit distinct adsorption selectivity between sulfidized and pristine nanomaterials, sulfidation altered the extents of impact of nanomaterials on the conformation and likely functions of the adsorbed proteins. These findings unearth a previously neglected mechanism via which environmental sulfidation process mediates the biological effects of soft-metal-containing nanomaterials.