Bovine hemoglobin adsorption onto modified silica nanoparticles: Multi-spectroscopic measurements based on kinetics and protein conformation

Butane Tetracarboxylic Acid Grafted on Polymeric Nanofibrous Aerogels for Highly Efficient Protein Absorption and Separation

Developing high-performance and low-cost protein purification materials is of great importance to meet the demands for highly purified proteins in biotechnological industries. Herein, a facile strategy was developed to design and construct high-efficiency protein absorption and separation media by combining aerogels' molding techniques and impregnation processes. Poly (ethylene-co-vinyl alcohol) (EVOH) nanofibrous aerogels (NFAs) were modified by grafting butane tetracarboxylic acid (BTCA) over them in situ. This modification was carried out using polyphosphoric acid as a catalyst. The resulting EVOH/BTCA NFAs exhibited favorable comprehensive properties. Benefiting from the highly interconnected porous structure, good underwater compressive properties, and abundant absorption ligands, the obtained EVOH/BTCA NFAs possessed a high static absorption capacity of 1082.13 mg/g to lysozyme and a short absorption equilibrium time of about 6 h. A high saturated dynamic absorption capacity for lysozyme (716.85 mg/g) was also realized solely by gravity. Furthermore, EVOH/BTCA NFAs displayed excellent reusability, good acid and alkaline resistance, and unique absorption selectivity performance. The successful synthesis of such aerogels can provide a potential candidate for next-generation protein absorbents for bio-separation and purification engineering.

Understanding protein-nanoparticle interactions leading to protein corona formation: In vitro - in vivo correlation study

Nanoparticles (NPs) in contact with biological fluids form a biomolecular corona through interactions with proteins, lipids, and sugars, acquiring new physicochemical properties. This work explores the interaction between selected proteins (hemoglobin and fetuin-A) that may alter NP circulation time and NPs of different surface charges (neutral, positive, and negative). The interaction with key proteins albumin and transferrin, the two of the most abundant proteins in plasma was also studied. Binding affinity was investigated using quartz crystal microbalance and fluorescence quenching, while circular dichroism assessed potential conformational changes. The data obtained from in vitro experiments were compared to in vivo protein corona data. The results indicate that electrostatic interactions primarily drive protein-NP interactions, and higher binding affinity does not necessarily translate into more significant structural changes. In vitro and single protein-NP studies provide valuable insights that can be correlated with in vivo observations, opening exciting possibilities for future protein corona studies.

Characterization of a chlorine resistant and hydrophilic TiO2/calcium alginate hydrogel filtration membrane used for protein purification maintaining protein structure

The development of membranes for protein purification has stringent requirement of disinfection resistance, low protein adsorption and anti-fouling, without changing protein structure. In this study, hydrophilic titanium dioxide (TiO2)/calcium alginate (TiO2/CaAlg) hydrogel membranes were prepared by a simple ionic cross-linking method. The effects of the porogenic agent polyethylene glycol (PEG) concentration, the molecular weight of PEG, and the concentration of TiO2 on the filtration properties were systematically investigated. The TiO2/CaAlg membrane exhibited excellent bovine serum albumin (BSA) rejection and anti-fouling properties. The mechanical properties and surface energy of the TiO2/CaAlg membrane were significantly improved. The chemical bonding mechanism of TiO2 and NaAlg was investigated by molecular dynamic simulation. The TiO2/CaAlg membrane had good chlorine resistance and could be disinfected or cleaned with sodium hypochlorite. The TiO2/CaAlg hydrogel membrane loaded with polyhydroxybutyrate (PHB) nanofibers maintained high flux (136.7 L/m2h) and high BSA rejection (98.0 %) at 0.1 MPa. The results of circular dichroism and synchronous fluorescence indicated that the secondary structure of BSA was maintained after membrane separation. This study provides one method for the preparation of green and environmentally friendly membrane for protein purification.

Interactions between proteins and cellulose in a liquid crystalline media: Design of a droplet based experimental platform

Model systems are needed to provide controlled environment for the understanding of complex phenomena. Interaction between polysaccharides and proteins in dense medium are involved in numerous complex systems such as biomass conversion or plant use for food processing or biobased materials. In this work, cellulose nanocrystals (CNCs) were used to study proteins in a dense and organized cellulosic environment. This environment was designed within microdroplets using a microfluidic setup, and applied to two proteins, bovine serum albumin (BSA) and a GH7 endoglucanase, relevant to food and plant science, respectively. The CNC at 56.5 g/L organized in liquid crystalline structure and the distribution of the proteins was probed using synchrotron deep-UV radiation. The proteins were homogeneously distributed throughout the volume, but BSA significantly disturbed the droplet global organization, preferring partition in hydrophilic external micelles. In contrast, GH7 partitioned with the CNCs showing stronger non-polar interaction but without disruption of the system organization. Such results pave the road for the development of more complex polysaccharides - proteins in-vitro models.

Identification of the Proteins Determining the Blood Circulation Time of Nanoparticles

The therapeutic efficacy and adverse impacts of nanoparticles (NPs) are strongly dependent on their systemic circulation time. The corona proteins adsorbed on the NPs determine their plasma half-lives, and hence, it is crucial to identify the proteins shortening or extending their circulation time. In this work, the in vivo circulation time and corona composition of superparamagnetic iron oxide nanoparticles (SPIONs) with different surface charges/chemistries were analyzed over time. SPIONs with neutral and positive charges showed the longest and shortest circulation times, respectively. The most striking observation was that corona-coated NPs with similar opsonin/dysopsonin content showed different circulation times, implying these biomolecules are not the only contributing factors. Long-circulating NPs adsorb higher concentrations of osteopontin, lipoprotein lipase, coagulation factor VII, matrix Gla protein, secreted phosphoprotein 24, alpha-2-HS-glycoprotein, and apolipoprotein C-I, while short-circulating NPs adsorb higher amounts of hemoglobin. Therefore, these proteins may be considered to be determining factors governing the NP systemic circulation time.

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.

Nanoparticle Effects on Stress Response Pathways and Nanoparticle-Protein Interactions

Nanoparticles (NPs) are increasingly used in a wide variety of applications and products; however, NPs may affect stress response pathways and interact with proteins in biological systems. This review article will provide an overview of the beneficial and detrimental effects of NPs on stress response pathways with a focus on NP-protein interactions. Depending upon the particular NP, experimental model system, and dose and exposure conditions, the introduction of NPs may have either positive or negative effects. Cellular processes such as the development of oxidative stress, the initiation of the inflammatory response, mitochondrial function, detoxification, and alterations to signaling pathways are all affected by the introduction of NPs. In terms of tissue-specific effects, the local microenvironment can have a profound effect on whether an NP is beneficial or harmful to cells. Interactions of NPs with metal-binding proteins (zinc, copper, iron and calcium) affect both their structure and function. This review will provide insights into the current knowledge of protein-based nanotoxicology and closely examines the targets of specific NPs.

A molecularly imprinted nanoreactor with spatially confined effect fabricated with nano-caged cascaded enzymatic system for specific detection of monosaccharides

Glucose oxidase (GOx), traditionally regarded as an oxidoreductase with high β-D-glucose specificity, has been widely applied as sensing probe for β-D-glucose detection. However, it is found that the specificity of GOx is not absolute and GOx cannot decern β-D-glucose among its isomers such as xylose, mannose and galactose. The existence of the other monosaccharides in sensing system could compromise the sensitivity for β-D-glucose, therefore, it is of great urgency to achieve the highly specific catalytic performance of GOx. Herein, porous metal-organic frameworks (MOF) are prepared as the host matrix for immobilization of both GOx and bovine hemoglobin (BHb), obtained a cascaded catalytic system (MOF@GOx@BHb) with both enhanced GOx activity and peroxidase-like activity owing to the spatially confined effect. Then, using β-D-glucose as both template molecules and substances, hydroxyl radicals are produced continuously and applied for initiating the polymerization of molecular imprinting polymers (MIPs) on the surface of MOF@GOx@BHb. Impressively, the obtaining molecularly imprinted GOx (noted as MOF@GOx@BHb-MIPs) achieves the highly sensitive and specific detection of β-D-glucose in the concentration range of 0.5-20 μM with the LOD = 0.4 μM (S/N = 3) by colorimetry. Similarly, MOF@GOx@BHb-MIPs are subsequently obtained using mannose, xylose and galactose as template molecules, respectively, and also show satisfied specific catalytic activity towards corresponding templates, indicating the effectiveness of the proposed strategy to achieve highly specific catalytic performance of GOx.

Protein corona, understanding the nanoparticle-protein interactions and future perspectives: A critical review

Proteins are biopolymers of highly varied structures taking part in almost all processes occurring in living cells. When nanoparticles (NPs) interact with proteins in biological environments, they are surrounded by a layer of biomolecules, mainly proteins adsorbing to the surfaces. This protein rich layer formed around NPs is called the "protein corona". Consequential interactions between NPs and proteins are governed due to the characteristics of the corona. The features of NPs such as the size, surface chemistry, charge are the critical factors influencing the behavior of protein corona. Molecular properties and protein corona composition affect the cellular uptake of NPs. Understanding and analyzing protein corona formation in relation to protein-NP properties, and elucidating its biological implications play an important role in bio-related nano-research studies. Protein-NP interactions have been studied extensively for the purpose of investigating the potential use of NPs as carriers in drug delivery systems. Further study should focus on exploring the effects of various characteristic parameters, such as the particle size, modifier type, temperature, pH on protein-NP interactions, providing toxicity information of novel NPs. In this contribution, important aspects related to protein corona forming, influential factors, novel findings and future perspectives on protein-NP interactions are overviewed.