Protein adsorption onto silica nanoparticles: conformational changes depend on the particles' curvature and the protein stability

A comprehensive investigation of the interactions of human serum albumin with polymeric and hybrid nanoparticles

Nanoparticles (NPs) engineered as drug delivery systems continue to make breakthroughs as they offer numerous advantages over free therapeutics. However, the poor understanding of the interplay between the NPs and biomolecules, especially blood proteins, obstructs NP translation to clinics. Nano-bio interactions determine the NPs' in vivo fate, efficacy and immunotoxicity, potentially altering protein function. To fulfill the growing need to investigate nano-bio interactions, this study provides a systematic understanding of two key aspects: (i) protein corona (PC) formation and (ii) NP-induced modifications on protein's structure and stability. A methodology was developed by combining orthogonal techniques to analyze both quantitative and qualitative aspects of nano-bio interactions, using human serum albumin (HSA) as a model protein. Protein quantification via liquid chromatography-mass spectrometry, and capillary zone electrophoresis (CZE) clarified adsorbed protein quantity and stability. CZE further unveiled qualitative insights into HSA forms (native, glycated HSA and cysteinylated), while synchrotron radiation circular dichroism enabled analyzing HSA's secondary structure and thermal stability. Comparative investigations of NP cores (organic vs. hybrid), and shells (with or without polyethylene glycol (PEG)) revealed pivotal factors influencing nano-bio interactions. Polymeric NPs based on poly(lactic-co-glycolic acid) (PLGA) and hybrid NPs based on metal-organic frameworks (nanoMOFs) presented distinct HSA adsorption profiles. PLGA NPs had protein-repelling properties while inducing structural modifications on HSA. In contrast, HSA exhibited a high affinity for nanoMOFs forming a PC altering thereby the protein structure. A shielding effect was gained through PEGylation for both types of NPs, avoiding the PC formation as well as the alteration of unbound HSA structure.

Effect of Nanoparticle Curvature on Its Interaction with Serum Proteins

The size or the curvature of nanoparticles (NPs) plays an important role in regulating the composition of the protein corona. However, the molecular mechanisms of how curvature affects the interaction of NPs with serum proteins still remain elusive. In this study, we employ all-atom molecular dynamics simulations to investigate the interactions between two typical serum proteins and PEGylated Au NPs with three different surface curvatures (0, 0.1, and 0.5 nm-1, respectively). The results show that for proteins with a regular shape, the binding strength between the serum protein and Au NPs decreases with increasing curvature. For irregularly shaped proteins with noticeable grooves, the binding strength between the protein and Au NPs does not change obviously with increasing curvature in the cases of smaller curvature. However, as the curvature continues to increase, Au NPs may act as ligands firmly adsorbed in the protein grooves, significantly enhancing the binding strength. Overall, our findings suggest that the impact of NP curvature on protein adsorption may be nonmonotonic, which may provide useful guidelines for better design of functionalized NPs in biomedical applications.

The Impact of Virgin and Aged Microstructured Plastics on Proteins: The Case of Hemoglobin Adsorption and Oxygenation

Plastic particles, particularly micro- and nanoparticles, are emerging pollutants due to the ever-growing amount of plastics produced across a wide variety of sectors. When plastic particles enter a biological medium, they become surrounded by a corona, giving them their biological identity and determining their interactions in the living environment and their biological effects. Here, we studied the interactions of microstructured plastics with hemoglobin (Hb). Virgin polyethylene microparticles (PEMPs) and polypropylene microparticles (PPMPs) as well as heat- or irradiation-aged microparticles (ag-PEMPs and ag-PPMPs) were used to quantify Hb adsorption. Polypropylene filters (PP-filters) were used to measure the oxygenation of adsorbed Hb. Microstructured plastics were characterized using optical microscopy, SAXS, ATR-FTIR, XPS, and Raman spectroscopy. Adsorption isotherms showed that the Hb corona thickness is larger on PPMPs than on PEMPs and Hb has a higher affinity for PPMPs than for PEMPs. Hb had a lower affinity for ag-PEMPs and ag-PPMPs, but they can be adsorbed in larger amounts. The presence of partial charges on the plastic surface and the oxidation rate of microplastics may explain these differences. Tonometry experiments using an original method, the diffuse reflection of light, showed that adsorbed Hb on PP-filters retains its cooperativity, but its affinity for O2 decreases significantly.

A Review for Uncovering the "Protein-Nanoparticle Alliance": Implications of the Protein Corona for Biomedical Applications

Understanding both the physicochemical and biological interactions of nanoparticles is mandatory for the biomedical application of nanomaterials. By binding proteins, nanoparticles acquire new surface identities in biological fluids, the protein corona. Various studies have revealed the dynamic structure and nano-bio interactions of the protein corona. The binding of proteins not only imparts new surface identities to nanoparticles in biological fluids but also significantly influences their bioactivity, stability, and targeting specificity. Interestingly, recent endeavors have been undertaken to harness the potential of the protein corona instead of evading its presence. Exploitation of this 'protein-nanoparticle alliance' has significant potential to change the field of nanomedicine. Here, we present a thorough examination of the latest research on protein corona, encompassing its formation, dynamics, recent developments, and diverse bioapplications. Furthermore, we also aim to explore the interactions at the nano-bio interface, paving the way for innovative strategies to advance the application potential of the protein corona. By addressing challenges and promises in controlling protein corona formation, this review provides insights into the evolving landscape of the 'protein-nanoparticle alliance' and highlights emerging.

Albumin Retains Its Transport Function after Interaction with Cerium Dioxide Nanoparticles

The interaction of inorganic nanomaterials with biological fluids containing proteins can lead not only to the formation of a protein corona and thereby to a change in the biological activity of nanoparticles but also to a significant effect on the structural and functional properties of the biomolecules themselves. This work studied the interaction of nanoscale CeO2, the most versatile nanozyme, with human serum albumin (HSA). Fourier transform infrared spectroscopy, MALDI-TOF mass spectrometry, UV-vis spectroscopy, and fluorescence spectroscopy confirmed the formation of HSA-CeO2 nanoparticle conjugates. Changes in protein conformation, which depend on the concentration of both citrate-stabilized CeO2 nanoparticles and pristine CeO2 nanoparticles, did not affect albumin drug-binding sites and, accordingly, did not impair the HSA transport function. The results obtained shed light on the biological consequences of the CeO2 nanoparticles' entrance into the body, which should be taken into account when engineering nanobiomaterials to increase their efficiency and reduce the side effects.

Novel biocatalysts based on enzymes in complexes with nano- and micromaterials

In today's world, there is a wide array of materials engineered at the nano- and microscale, with numerous applications attributed to these innovations. This review aims to provide a concise overview of how nano- and micromaterials are utilized for enzyme immobilization. Enzymes act as eco-friendly biocatalysts extensively used in various industries and medicine. However, their widespread adoption faces challenges due to factors such as enzyme instability under different conditions, resulting in reduced effectiveness, high costs, and limited reusability. To address these issues, researchers have explored immobilization techniques using nano- and microscale materials as a potential solution. Such techniques offer the promise of enhancing enzyme stability against varying temperatures, solvents, pH levels, pollutants, and impurities. Consequently, enzyme immobilization remains a subject of great interest within both the scientific community and the industrial sector. As of now, the primary goal of enzyme immobilization is not solely limited to enabling reusability and stability. It has been demonstrated as a powerful tool to enhance various enzyme properties and improve biocatalyst performance and characteristics. The integration of nano- and microscale materials into biomedical devices is seamless, given the similarity in size to most biological systems. Common materials employed in developing these nanotechnology products include synthetic polymers, carbon-based nanomaterials, magnetic micro- and nanoparticles, metal and metal oxide nanoparticles, metal-organic frameworks, nano-sized mesoporous hydrogen-bonded organic frameworks, protein-based nano-delivery systems, lipid-based nano- and micromaterials, and polysaccharide-based nanoparticles.

Immobilization of Cellulase Enzymes on Single-Walled Carbon Nanotubes for Recycling of Enzymes and Better Yield of Bioethanol Using Computer Simulations

The utilization of microbial cellulase enzymes for transforming plant biomass into biofuel or bioethanol, which can serve as a substitute for fossil fuel, is a subject of growing interest. Nonetheless, large-scale production of biofuel using cellulases is not economically feasible as the extraction of these enzymes from diverse microorganisms is an expensive process. To address this issue, immobilizing the enzyme to a substrate material, e.g., carbon nanotubes (CNTs), to recycle without a significant decline in its catalytic activity is a promising solution. Due to the hydrophobic nature of CNTs, we employed molecular docking and network analysis methodologies to identify potential CNT-binding sites on the outer surface of a wild-type cellulase enzyme, CelS. Classical molecular dynamics simulations of CNT-bound CelS through one of the selected binding sites resulted in negligible changes in the secondary structure of the enzyme and its catalytic domain, implying the least possible effect on the catalytic activity post-immobilization. Furthermore, our study reveals that while the unfolding near the CNT-binding region in CelS is more pronounced when the enzyme is interacting with a wider CNT, resulting in enhanced contact area and improved binding affinity, its impact on the overall CelS structure is relatively less significant when compared to thinner CNTs. Particularly, CNTs of diameter ∼12 Å can serve as a favorable option for substrate materials in cellulase immobilization. Our study also provides critical insights into the binding mechanisms between cellulase and CNTs, which could lead to the development of more efficient biocatalysts for biofuel production.

Attaching protein-adsorbing silica particles to the surface of cotton substrates for bioaerosol capture including SARS-CoV-2

The novel coronavirus pandemic (COVID-19) has necessitated a global increase in the use of face masks to limit the airborne spread of the virus. The global demand for personal protective equipment has at times led to shortages of face masks for the public, therefore makeshift masks have become commonplace. The severe acute respiratory syndrome caused by coronavirus-2 (SARS-CoV-2) has a spherical particle size of ~97 nm. However, the airborne transmission of this virus requires the expulsion of droplets, typically ~0.6-500 µm in diameter (by coughing, sneezing, breathing, and talking). In this paper, we propose a face covering that has been designed to effectively capture SARS-CoV-2 whilst providing uncompromised comfort and breathability for the wearer. Herein, we describe a material approach that uses amorphous silica microspheres attached to cotton fibres to capture bioaerosols, including SARS CoV-2. This has been demonstrated for the capture of aerosolised proteins (cytochrome c, myoglobin, ubiquitin, bovine serum albumin) and aerosolised inactivated SARS CoV-2, showing average filtration efficiencies of ~93% with minimal impact on breathability.

An Approach for In-Situ Detection of Gold Colloid Aggregates Amyloid Formations Within The Hippocampus of The Cohen's Alzheimer's Disease Rat Model By Surface Enhanced Raman Scattering Methods

BACKGROUND

Amyloid beta (Aβ) peptides, such as Aβ_1-40 or Aβ_1-42 are regarded as hallmark neuropathological biomarkers associated with Alzheimer's disease (AD). The formation of an aggregates by Aβ_1-40 or Aβ_1-42-coated gold nano-particles are hypothesized to contain conformation of Aβ oligomers, which could exist only at an initial stage of fibrillogenesis.

NEW METHOD

The attempt of in-situ detection of externally initiated gold colloid (ca. 80nm diameter) aggregates in the middle section of the hippocampus of the Long Evans Cohen's Alzheimer's disease rat model was conducted through the Surface Enhanced Raman Scattering (SERS) method.

RESULTS

The SERS spectral features contained modes associated with β-sheet interactions and a significant number of modes that were previously reported in SERS shifts for Alzheimer diseased rodent and human brain tissues; thereby, strongly implying a containment of amyloid fibrils. The spectral patterns were further examined and compared with those collected from in-vitro gold colloid aggregates which were formed from Aβ_1-40 - or Aβ_1-42 -coated 80nm gold colloid under pH ~4, pH ~7, and pH ~10, and the best matched datasets were found with that of the aggregates of Aβ_1-42 -coated 80nm gold colloid at ~pH 4.0. The morphology and physical size of this specific gold colloid aggregate was clearly different from those found in-vitro.

COMPARISON WITH EXISTING METHOD(S)

The amyloid fibril with a β-sheet conformation identified in previously reported in AD mouse/human brain tissues was involved in a formation of the gold colloid aggregates. However, to our surprise, best explanation for the observed SERS spectral features was possible with those in vitro Aβ_1-42 -coated 80nm gold colloid under pH ~4.

CONCLUSIONS

A formation of gold colloid aggregates was confirmed in the AD rat hippocampal brain section with unique physical morphology compared to those observed in in-vitro Aβ_1-42 or Aβ_1-40 mediated gold colloid aggregates. It was concluded that a β-sheet conformation identified in previously reported in AD mouse/human brain tissues was in volved in a formation of the gold colloid aggregates.

Developing Enzyme Immobilization with Fibrous Membranes: Longevity and Characterization Considerations

Fibrous membranes offer broad opportunities to deploy immobilized enzymes in new reactor and application designs, including multiphase continuous flow-through reactions. Enzyme immobilization is a technology strategy that simplifies the separation of otherwise soluble catalytic proteins from liquid reaction media and imparts stabilization and performance enhancement. Flexible immobilization matrices made from fibers have versatile physical attributes, such as high surface area, light weight, and controllable porosity, which give them membrane-like characteristics, while simultaneously providing good mechanical properties for creating functional filters, sensors, scaffolds, and other interface-active biocatalytic materials. This review examines immobilization strategies for enzymes on fibrous membrane-like polymeric supports involving all three fundamental mechanisms of post-immobilization, incorporation, and coating. Post-immobilization offers an infinite selection of matrix materials, but may encounter loading and durability issues, while incorporation offers longevity but has more limited material options and may present mass transfer obstacles. Coating techniques on fibrous materials at different geometric scales are a growing trend in making membranes that integrate biocatalytic functionality with versatile physical supports. Biocatalytic performance parameters and characterization techniques for immobilized enzymes are described, including several emerging techniques of special relevance for fibrous immobilized enzymes. Diverse application examples from the literature, focusing on fibrous matrices, are summarized, and biocatalyst longevity is emphasized as a critical performance parameter that needs increased attention to advance concepts from lab scale to broader utilization. This consolidation of fabrication, performance measurement, and characterization techniques, with guiding examples highlighted, is intended to inspire future innovations in enzyme immobilization with fibrous membranes and expand their uses in novel reactors and processes.

The interaction mechanism of plasma iron transport protein transferrin with nanoparticles

In the biological systems, exposure to nanoparticles (NPs) can cause complicated interactions with proteins, the formation of protein corona and structural changes to proteins. These changes depend not only on NP physicochemical properties, but also on the intrinsic stability of protein molecules. Although, the formation of protein corona on the surface of NPs and the underlying mechanisms have been fully explored in various studies, no comprehensive review has discussed the direct biochemical and biophysical interactions between NPs and blood proteins, particularly transferrin. In this review, we first discussed the interaction of NPs with proteins to comprehend the effects of physicochemical properties of NPs on protein structure. We then overviewed the transferrin structure and its direct interaction with NPs to explore transferrin stability and its iron ion (Fe³⁺) release behavior. Afterwards, we surveyed the various biological functions of transferrin, such as Fe³⁺ binding, receptor binding, antibacterial activity, growth, differentiation, and coagulation, followed by the application of transferrin-modified NPs in the development of drug delivery systems for cancer therapy. We believe that this study can provide useful insight into the design and development of bioconjugates containing NP-transferrin for potential biomedical applications.

Mechanistic Understanding of Protein Corona Formation around Nanoparticles: Old Puzzles and New Insights

Although a wide variety of nanoparticles (NPs) have been engineered for use as disease markers or drug delivery agents, the number of nanomedicines in clinical use has hitherto remained small. A key obstacle in nanomedicine development is the lack of a deep mechanistic understanding of NP interactions in the bio-environment. Here, the focus is on the biomolecular adsorption layer (protein corona), which quickly enshrouds a pristine NP exposed to a biofluid and modifies the way the NP interacts with the bio-environment. After a brief introduction of NPs for nanomedicine, proteins, and their mutual interactions, research aimed at addressing fundamental properties of the protein corona, specifically its mono-/multilayer structure, reversibility and irreversibility, time dependence, as well as its role in NP agglomeration, is critically reviewed. It becomes quite evident that the knowledge of the protein corona is still fragmented, and conflicting results on fundamental issues call for further mechanistic studies. The article concludes with a discussion of future research directions that should be taken to advance the understanding of the protein corona around NPs. This knowledge will provide NP developers with the predictive power to account for these interactions in the design of efficacious nanomedicines.

Carbon Nanomaterials: Emerging Roles in Immuno-Oncology

Cancer immunotherapy has made breakthrough progress in cancer treatment. However, only a subset of patients benefits from immunotherapy. Given their unique structure, composition, and interactions with the immune system, carbon nanomaterials have recently attracted tremendous interest in their roles as modulators of antitumor immunity. Here, we focused on the latest advances in the immunological effects of carbon nanomaterials. We also reviewed the current preclinical applications of these materials in cancer therapy. Finally, we discussed the challenges to be overcome before the full potential of carbon nanomaterials can be utilized in cancer therapies to ultimately improve patient outcomes.

Role of the Protein Corona in the Colloidal Behavior of Microplastics

Microparticles of polyethylene and polypropylene are largely found in aquatic environments because they are the most produced and persistent plastic materials. Once in biological media, they are covered by a layer of molecules, the so-called corona, mostly composed of proteins. A yeast protein extract from Saccharomyces cerevisiae was used as a protein system to observe interactions in complex biological media. Proteins, acting as surfactants and providing hydrophilic surfaces, allow the dispersion of highly hydrophobic particles in water and stabilize them. After 24 h, the microplastic quantity was up to 1 × 10¹¹ particles per liter, whereas without protein, no particles remained in solution. Label-free imaging of the protein corona by synchrotron radiation deep UV fluorescence microscopy (SR-DUV) was performed. In situ images of the protein corona were obtained, and the adsorbed protein quantity, the coverage rate, and the corona heterogeneity were determined. The stability kinetics of the microplastic suspensions were measured by light transmission using a Turbiscan analyzer. Together, the microscopic and kinetics results demonstrate that the protein corona can very efficiently stabilize microplastics in solution provided that the protein corona quality is sufficient. Microplastic stability depends on different parameters such as the particle's intrinsic properties (size, density, hydrophobicity) and the protein corona formation that changes the particle wettability, electrostatic charge, and steric hindrance. By controlling these parameters with proteins, it becomes possible to keep microplastics in and out of solution, paving the way for applications in the field of microplastic pollution control and remediation.

Synchrotron radiation circular dichroism spectroscopy reveals that gold and silver nanoparticles modify the secondary structure of a lung surfactant protein B analogue

Inhaled nanoparticles (NPs) depositing in the alveolar region of the lung interact initially with a surfactant layer and in vitro studies have demonstrated that NPs can adversely affect the biophysical function of model pulmonary surfactants (PS), of which surfactant protein B (SP-B) is a key component. Other studies have demonstrated the potential for NPs to modify the structure and function of proteins. It was therefore hypothesised that NPs may affect the biophysical function of PS by modifying the structure of SP-B. Synchrotron radiation circular dichroism (SRCD) spectroscopy was used to explore the effect of various concentrations of gold nanoparticles (AuNPs) (5, 10, 20 nm), silver nanoparticles (AgNPs) (10 nm) and silver citrate on the secondary structure of surfactant protein B analogue, SP-B_1-25, in a TFE/PB dispersion. For Au and Ag NPs the SRCD spectra indicated a concentration dependent reduction in the α-helical structure of SP-B_1-25 (5 nm AuNP ≈ 10 nm AgNP ≫ 10 nm AuNP > 20 nm AuNP). For AuNPs the effect was greater for the 5 nm size, which was not fully explained by consideration of surface area. The impact of the 10 nm AgNPs was greater than that of the 10 nm AuNPs and the effect of AgNPs was greater than that of silver citrate at equivalent Ag mass concentrations. For 10 nm AuNPs, SRCD spectra for dispersions in, the more physiologically relevant, DPPC showed a similar concentration dependent pattern. The results demonstrate the potential for inhaled NPs to modify SP-B_1-25 structure and thus potentially adversely impact the physiological function of the lung, however, further studies are necessary to confirm this.

Gold Nanoparticles Are an Immobilization Platform for Active and Stable Acetylcholinesterase: Demonstration of a General Surface Protein Functionalization Strategy

Immobilizing enzymes onto abiological surfaces is a key step for developing protein-based technologies that can be useful for applications such as biosensors and biofuel cells. A central impediment for the advancement of this effort is a lack of generalizable strategies for functionalizing surfaces with proteins in ways that prevent unfolding, aggregation, and uncontrolled binding, requiring surface chemistries to be developed for each surface-enzyme pair of interest. In this work, we demonstrate a significant advancement toward addressing this problem using a gold nanoparticle (AuNP) as an initial scaffold for the chemical bonding of the enzyme acetylcholinesterase (AChE), forming the conjugate AuNP-AChE. This can then be placed onto chemically and structurally distinct surfaces (e.g., metals, semiconductors, plastics, etc.), thereby bypassing the need to develop surface functionalization strategies for every substrate or condition of interest. Carbodiimide crosslinker chemistry was used to bind surface lysine residues in AChE to AuNPs functionalized with ligands containing carboxylic acid tails. Using amino acid analysis, we found that on average, 3.3 ± 0.1 AChE proteins were bound per 5.22 ± 1.25 nm AuNP. We used circular dichroism spectroscopy to measure the structure of the bound protein and determined that it remained essentially unchanged after binding. Finally, we performed Michaelis-Menten kinetics to determine that the enzyme retained 18.2 ± 2.0% of its activity and maintained that activity over a period of at least three weeks after conjugation to AuNPs. We hypothesize that structural changes to the peripheral active site of AChE are responsible for the differences in activity of bound AChE and unbound AChE. This work is a proof-of-concept demonstration of a generalizable method for placing proteins onto chemically and structurally diverse substrates and materials without the need for surface functionalization strategies.

Nanospacial effect of citric acid-coordinated hydroxyapatite nanoparticle films on protein adsorption and cell adhesion states

Hydroxyapatite (HA) and citric acid (Cit)-coordinated HA (Cit/HA) nanoparticle films with different nanospaces were used to examine the nanospacial effect on the protein adsorption behavior and initial osteoblast-like cell adhesion ability through the premise of the stability and ionic dissociation characteristics of the films in biological solution. In particular, the Cit/HA nanoparticle film with a nanospace of 4.2 nm could realize massive and stereoscopic adsorption of proteins due to its larger specific surface area and smaller nanospace as compared with the case of the HA nanoparticle film. It was also found that the α-helix and (β-sheet + β-turn) component ratios of the adsorbed fetal bovine serum proteins on the Cit/HA nanoparticle films increased as compared with the case of the HA nanoparticle film through the secondary structure analysis of the adsorbed proteins, which contributed to the good initial cell culture properties on the film surfaces. Therefore, we successfully realized the control of protein adsorption states using different nanospacial HA and Cit/HA nanoparticle films to achieve excellent initial cell culture properties, which would provide new insights into the creation of novel cell culture substrate surfaces in the regenerative medicine fields.

Predicting protein function and orientation on a gold nanoparticle surface using a residue-based affinity scale

The orientation adopted by proteins on nanoparticle surfaces determines the nanoparticle's bioactivity and its interactions with living systems. Here, we present a residue-based affinity scale for predicting protein orientation on citrate-gold nanoparticles (AuNPs). Competitive binding between protein variants accounts for thermodynamic and kinetic aspects of adsorption in this scale. For hydrophobic residues, the steric considerations dominate, whereas electrostatic interactions are critical for hydrophilic residues. The scale rationalizes the well-defined binding orientation of the small GB3 protein, and it subsequently predicts the orientation and active site accessibility of two enzymes on AuNPs. Additionally, our approach accounts for the AuNP-bound activity of five out of six additional enzymes from the literature. The model developed here enables high-throughput predictions of protein behavior on nanoparticles, and it enhances our understanding of protein orientation in the biomolecular corona, which should greatly enhance the performance and safety of nanomedicines used in vivo.

Charge and hydrophobicity of amyloidogenic protein/peptide templates regulate the growth and morphology of gold nanoparticles

Biomolecules are known to interact with metals and produce nanostructured hybrid materials with diverse morphologies and functions. In spite of the great advancement in the principles of biomimetics for designing complex nano-bio structures, the interplay between the physical properties of biomolecules such as sequence, charge, and hydrophobicity with predictable morphology of the resulting nanomaterials is largely unknown. Here, using various amyloidogenic proteins/peptides and their corresponding fibrils in combination with different pH, we show defined principle for gold nanocrystal growth into triangular and supra-spheres with high prediction. Using a combination of different biophysical and structural techniques, we establish the mechanism of nucleation and crystal growth of gold nanostructures and show the effective isolation of intact nanostructures from amyloid templates using protein digestion. This study will significantly advance our design principle for bioinspired materials for specific functions with great predictability.

Deciphering the Emulsification Process to Create an Albumin-Perfluorocarbon-(o/w) Nanoemulsion with High Shelf Life and Bioresistivity

This work aimed at the development of a stable albumin-perfluorocarbon (o/w) emulsion as an artificial oxygen carrier suitable for clinical application. So far, albumin-perfluorocarbon-(o/w) emulsions have been successfully applied in preclinical trials. Cross-linking a variety of different physical and chemical methods for the characterization of an albumin-perfluorocarbon (PFC)-(o/w) emulsion was necessary to gain a deep understanding of its specific emulsification processes during high-pressure homogenization. High-pressure homogenization is simple but incorporates complex physical reactions, with many factors influencing the formation of PFC droplets and their coating. This work describes and interprets the impact of albumin concentration, homogenization pressure, and repeated microfluidizer passages on PFC-droplet formation; its influence on storage stability; and the overcoming of obstacles in preparing stable nanoemulsions. The applied methods comprise dynamic light scattering, static light scattering, cryo- and non-cryo-scanning and transmission electron microscopies, nuclear magnetic resonance spectroscopy, light microscopy, amperometric oxygen measurements, and biochemical methods. The use of this wide range of methods provided a sufficiently comprehensive picture of this polydisperse emulsion. Optimization of PFC-droplet formation by means of temperature and pressure gradients results in an emulsion with improved storage stability (tested up to 5 months) that possibly qualifies for clinical applications. Adaptations in the manufacturing process strikingly changed the physical properties of the emulsion but did not affect its oxygen capacity.

Nano-size dependent protein corona formation by SARS-CoV-2 Omicron spike protein over gold nano-colloid and reversible aggregation

The adsorption process of SARS-CoV-2 Omicron spike protein to the nano-gold colloid surfaces was examined by monitoring the surface plasmon resonance (SPR) band shift of gold-nano particles ranging between diameters of d = 10–100 nm. The externally changed pH between 3 and 11 at 24.5 ± 0.4 °C initiated a reversible formation of the gold colloid aggregates, where formation/deformation of the aggregates were monitored by red/blue shift of the peak of the SPR band. There was no sign of reversible aggregation for d = 10, 15, and 20 nm gold colloids. A clear undulation of the peak shift corresponding to pH hopping between pH ~3 and ~11 was confirmed for colloidal d > 30 nm. This degree of the reversibility was compared to previously reported SARS-CoV-2 Alpha spike protein coated gold colloids. It was concluded that Omicron spike protein possesses a similar low affinity for gold nano particle d < 20 nm and possesses the higher affinity to the gold nanoparticles of d > 30 nm. However, the Omicron spike protein conformation was presumed to be more denatured compared to the SARS-CoV-2 Alpha spike protein. Our finding suggested Omicron spike protein was more acid labile/flexible.

β-Glucan-Functionalized Nanoparticles Down-Modulate the Proinflammatory Response of Mononuclear Phagocytes Challenged with Candida albicans

Systemic fungal infections are associated with significant morbidity and mortality, and Candida albicans is the most common causative agent. Recognition of yeast cells by immune cell surface receptors can trigger phagocytosis of fungal pathogens and a pro-inflammatory response that may contribute to fungal elimination. Nevertheless, the elicited inflammatory response may be deleterious to the host by causing excessive tissue damage. We developed a nanoparticle-based approach to modulate the host deleterious inflammatory consequences of fungal infection by using β1,3-glucan-functionalized polystyrene (β-Glc-PS) nanoparticles. β-Glc-PS nanoparticles decreased the levels of the proinflammatory cytokines TNF-α, IL-6, IL-1β and IL-12p40 detected in in vitro culture supernatants of bone marrow-derived dendritic cells and macrophage challenged with C. albicans cells. Moreover, β-Glc-PS nanoparticles impaired the production of reactive oxygen species by bone marrow-derived dendritic cells incubated with C. albicans. This immunomodulatory effect was dependent on the nanoparticle size. Overall, β-Glc-PS nanoparticles reduced the proinflammatory response elicited by fungal cells in mononuclear phagocytes, setting the basis for a targeted therapy aimed at protecting the host by lowering the inflammatory cost of infection.

Gas Cluster Ion Beams as a Versatile Soft-Landing Tool for the Controlled Construction of Thin (Bio)Films

Surface biofunctionalization with proteins is the key to many biomedical applications. In this study, a solvent-free method for the controlled construction of protein thin films is reported. Using large argon gas cluster ion beams, proteins are sputtered from a target (a pool of pure proteins), and collected on a chosen substrate, being nearly any solid material. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) revealed the presence of intact protein molecules on the collectors. Furthermore, lowering the energy per atom in the cluster projectiles down to 1 eV/atom allowed more than 60% of bradykinin molecules to be transferred intact. This protein deposition method offers a precise control of the film thickness as the transferred protein quantity is proportional to the argon clusters ion dose reached for the transfer. This major feature enables building protein films from (sub)mono- to multilayers, without upper limitation of the thickness. A procedure was developed to measure the film thickness in situ the ToF-SIMS instrument. The versatility and potential of this soft-landing alternative for further applications is demonstrated on the one hand by building a protein thin film at the surface of paper, a substrate hardly compatible with solution-based adsorption methods. On the other hand, the possibility to achieve alternated multilayer buildup is demonstrated with the construction of a bilayer composed of bradykinin and Irganox, with the two layers well separated. These results lay the first stone toward original and complex multilayers that could previously not be considered with solution-based adsorption methods, and this regardless of the substrate nature.

Interactions of proteins with metal-based nanoparticles from a point of view of analytical chemistry - Challenges and opportunities

Interactions of proteins with nanomaterials draw attention of many research groups interested in fundamental phenomena. However, alongside with valuable information regarding physicochemical aspects of such processes and their mechanisms, they more and more often prove to be useful from a point of view of bioanalytics. Deliberate use of processes based on adsorption of proteins on nanoparticles (or vice versa) allows for a development of new analytical methods and improvement of the existing ones. It also leads to obtaining of nanoparticles of desired properties and functionalities, which can be used as elements of analytical tools for various applications. Due to interactions with nanoparticles, proteins can also gain new functionalities or lose their interfering potential, which from perspective of bioanalytics seems to be very inviting and attractive. In the framework of this article we will discuss the bioanalytical potential of interactions of proteins with a chosen group of nanoparticles, and implementation of so driven processes for biosensing. Moreover, we will show both positive and negative (opportunities and challenges) aspects resulting from the presence of proteins in media/samples containing metal-based nanoparticles or their precursors.

Optimization of Nanohybrid Biosensors Based on Electro-Crosslinked Tannic Acid Capped Nanoparticles/Enzyme

Enzymes/Nanoparticles (NPs) bioconjugates are massively used nowadays to develop thin films for optical and electrochemical biosensors. Nevertheless, their full characterization as a thin coating onto electrodes remains little discussed, in particular the influence of NPs size and enzyme/NPs ratio used in the electrodeposition solution. In this study, GOx (160 kDa) and HRP (44 kDa) were used in association with tannic acid capped gold NPs (a series with sizes from 7 to 40 nm) to electrodeposit biosensor coatings, sensitive towards glucose and H2O2, respectively. The electrodeposition process was based on a mussel-inspired electro-crosslinking between gallol moieties of tannic acid (at the surface of NPs) and amine moieties of the enzymes. On one hand, the sensitivity of the GOx/NPs coatings depends strongly on the NP size and the enzyme/NPs molar ratio of the electrodeposition solution. An optimal sensitivity was obtained by electrodeposition of 11 nm NPs at a GOx/NPs molar ratio close to the theoretical value of the enzyme monolayer. On the other hand, a modest influence of the NPs size was found on the sensitivity in the case of the electrodeposited HRP/NPs coatings, reaching a plateau at the HRP/NPs molar ratio close to the value of the theoretical enzyme monolayer. In both cases, the enzyme/NPs molar ratio played a role in the sensitivity. To fully understand the parameters driving the biosensor sensitivity, a comprehensive evaluation of the colloidal state of the bioconjugates is proposed here.

Engineered Nanoparticle-Protein Interactions Influence Protein Structural Integrity and Biological Significance

Engineered nanoparticles (ENPs) are artificially synthesized particles with unique physicochemical properties. ENPs are being extensively used in several consumer items, elevating the probability of ENP exposure to biological systems. ENPs interact with various biomolecules like lipids, proteins, nucleic acids, where proteins are most susceptible. The ENP-protein interactions are mostly studied for corona formation and its effect on the bio-reactivity of ENPs, however, an in-depth understanding of subsequent interactive effects on proteins, such as alterations in their structure, conformation, free energy, and folding is still required. The present review focuses on ENP-protein interactions and the subsequent effects on protein structure and function followed by the therapeutic potential of ENPs for protein misfolding diseases.

Superior Binding of Proteins on a Silica Surface: Physical Insight into the Synergetic Contribution of Polyhistidine and a Silica-Binding Peptide

Controllable protein attachment onto solid interfaces is essential for the functionality of proteins with broad applications. Silica-binding peptides (SBPs) have emerged as an important tool enabling convenient binding of proteins onto a silica surface. Surprisingly, we found that removal of polyhistidines, a common tag for protein purification, dramatically decrease the binding affinity of a SBP-tagged nanobody onto a silica surface. We hypothesized that polyhistidines and SBPs can be combined to enhance affinity. Through a series of purposely designed SBPs, we identified that the relative orientation of amino acids is a key factor affecting the surface binding strength. One re-engineered SBP, SBP4, exhibits a 4000-fold improvement compared to the original sequence. Guided by physical insights, the work provides a simple strategy that can dramatically improve affinity between a SBP and a silica surface, promising a new way for controllable immobilization of proteins, as demonstrated using nanobodies.

Designing Functional Bionanoconstructs for Effective In Vivo Targeting

The progress achieved over the last three decades in the field of bioconjugation has enabled the preparation of sophisticated nanomaterial–biomolecule conjugates, referred to herein as bionanoconstructs, for a multitude of applications including biosensing, diagnostics, and therapeutics. However, the development of bionanoconstructs for the active targeting of cells and cellular compartments, both in vitro and in vivo, is challenged by the lack of understanding of the mechanisms governing nanoscale recognition. In this review, we highlight fundamental obstacles in designing a successful bionanoconstruct, considering findings in the field of bionanointeractions. We argue that the biological recognition of bionanoconstructs is modulated not only by their molecular composition but also by the collective architecture presented upon their surface, and we discuss fundamental aspects of this surface architecture that are central to successful recognition, such as the mode of biomolecule conjugation and nanomaterial passivation. We also emphasize the need for thorough characterization of engineered bionanoconstructs and highlight the significance of population heterogeneity, which too presents a significant challenge in the interpretation of in vitro and in vivo results. Consideration of such issues together will better define the arena in which bioconjugation, in the future, will deliver functional and clinically relevant bionanoconstructs.

Reversible assembly of silica nanoparticles at water-hydrocarbon interfaces controlled by SDS surfactant

Achieving reversible and tunable assembly of silica nanoparticles at liquid-liquid interfaces is vital for a wide range of scientific and technological applications including sustainable subsurface energy applications, catalysis, drug delivery and material synthesis. In this study, we report the mechanisms controlling the assembly of silica nanoparticles (dia. 50 nm and 100 nm) at water-heptane and water-toluene interfaces using sodium dodecyl sulfate (SDS) surfactant with concentrations ranging from 0.001-0.1 wt% using operando ultrasmall/small-angle X-ray scattering, cryogenic scanning electron microscopy imaging and classical molecular dynamics simulations. The results show that the assembly of silica nanoparticles at water-hydrocarbon interfaces can be tuned by controlling the concentrations of SDS. Silica nanoparticles are found to: (a) dominate the interfaces in the absence of interfacial SDS molecules, (b) coexist with SDS at the interfaces at low surfactant concentration of 0.001 wt% and (c) migrate toward the aqueous phase at a high SDS concentration of 0.1 wt%. Energetic analyses suggest that the van der Waals and electrostatic interactions between silica nanoparticles and SDS surfactants increase with SDS concentration. However, the favorable van der Waals and electrostatic interactions between the silica nanoparticles and toluene or heptane decrease with increasing SDS concentration. As a result, the silica nanoparticles migrate away from the water-hydrocarbon interface and towards bulk water at higher SDS concentrations. These calibrated investigations reveal the mechanistic basis for tuning silica nanoparticle assembly at complex interfaces.

The nanotopography of SiO2 particles impacts the selectivity and 3D fold of bound allergens

A detailed description of the changes that occur during the formation of protein corona represents a fundamental question in nanoscience, given that it not only impacts the behaviour of nanoparticles but also affects the bound proteins. Relevant questions include whether proteins selectively bind particles, whether a specific orientation is preferred for binding, and whether particle binding leads to a modulation of their 3D fold. For allergens, it is important to answer these questions given that all these effects can modify the allergenic response of atopic individuals. These potential impacts on the bound allergen are closely related to the specific properties of the involved nanoparticles. One important property influencing the formation of protein corona is the nanotopography of the particles. Herein, we studied the effect of nanoparticle porosity on allergen binding using mesoporous and non-porous SiO₂ NPs. We investigated (i) the selectivity of allergen binding from a mixture such as crude pollen extract, (ii) whether allergen binding results in a preferred orientation, (iii) the influence of binding on the conformation of the allergen, and (iv) how the binding affects the allergenic response. Nanotopography was found to play a major role in the formation of protein corona, impacting the physicochemical and biological properties of the NP-bound allergen. The porosity of the surface of the SiO₂ nanoparticles resulted in a higher binding capacity with pronounced selectivity for (preferentially) binding the major birch pollen allergen Bet v 1. Furthermore, the binding of Bet v 1 to the mesoporous rather than the non-porous SiO₂ nanoparticles influenced the 3D fold of the protein, resulting in at least partial unfolding. Consequently, this conformational change influenced the allergenic response, as observed by mediator release assays employing the sera of patients and immune effector cells. For an in-depth understanding of the bio-nano interactions, the properties of the particles need to be considered not only regarding the identity and morphology of the material, but also their nanotopography, given that porosity may greatly influence the structure, and hence the biological behaviour of the bound proteins. Thus, thorough structural investigations upon the formation of protein corona are important when considering immunological outcomes, as particle binding can influence the allergenic response elicited by the bound allergen.

The curious cases of nanoparticle induced amyloidosis during protein corona formation and anti-amyloidogenic nanomaterials: Paradox or prejudice?

Protein corona (PC) formation remains a major hurdle in the successful delivery of nanomedicines to the target sites. Interacting proteins have been reported to undergo structural changes on the nanoparticle (NP) surface which invariably impacts their biological activities. Such structural changes are the result of opening of more binding sites of proteins to adsorb on the NP surface. The process of conversion of α-helix proteins to their β-sheet enriched counterpart is termed as amyloidosis and in case of PC formation, NPs apparently play the crucial role of being the nucleation centres where this process takes place. Conversely, increasing numbers of artificial nano-chaperones are being used to treat the protein misfolding disorders. Anti-amyloidogenic nanomaterials (NM) have been gaining utmost importance in inhibiting Aβ42 (hallmark peptide for Alzheimer's disease) and Hen egg white lysozyme (HEWL, model protein for systemic amyloidosis) aggregation. Interestingly, in this process, NPs inhibit protein β-sheet enrichment. These two seemingly opposite roles of NPs, propelling confirmatory change onto the smorgasbord of adsorbed native proteins and the ability of NPs in inhibiting amyloidosis creates a paradox, which has not been discussed earlier. Here, we highlight the key points from both the facets of the NP behaviour with respect to their physicochemical properties and the nature of proteins they adsorb onto them to unravel the mystery. BRIEF: Protein corona formation remains a major hurdle in achieving the desired efficacy of nanomedicine. Proteins when interact with nanoparticle (NP) surface, undergo both structural and biological changes. Again, NPs are known to exhibit anti-amyloidogenic behaviour where these play the crucial role of preventing any change in their native structure. Such seemingly different roles of NPs need sincere inquisition.

Binding interactions of cationic gemini surfactants with gold nanoparticles-conjugated bovine serum albumin: A FRET/NSET, spectroscopic, and docking study

This work demonstrates binding interactions of two cationic gemini surfactants, 12-4-12,2Br^- and 12-8-12,2Br^- with gold nanoparticles (AuNPs)-conjugated bovine serum albumin (BSA) presenting binding isotherms from specific binding to saturation binding regions of surfactants. The binding isotherm has been successfully constructed using Förster's resonance energy transfer (FRET) and nanometal surface energy transfer (NSET) parameters calculated based on fluorescence quenching of donor, tryptophan (Trp) residue by acceptor, AuNP. Energy transfer efficiency (E_T) changes due to alteration in the donor-acceptor distance when surfactants interact with bioconjugates. A solid reverse relationship between α-helix and β-turn contents of BSA-AuNPs-conjugates is noted while interacting with surfactants. 12-8-12,2Br^- shows stronger binding interactions with BSA-bioconjugates than 12-4-12,2Br^-. The effect of bioconjugation on secondary/tertiary structures of BSA in the absence and presence of a surfactant is studied through circular dichroism, fluorescence, and Fourier transform infrared spectroscopic measurements. Motional restrictions imposed by AuNPs on Trp residues of folded and unfolded BSA have been investigated using red edge emission shift (REES) measurements. Finally, the molecular docking results present the modes of interactions of 12-4-12,2Br^- and 12-8-12,2Br^-, and Au-nanoclusters (Au₉₂) with BSA. An approach to describe the binding isotherms of surfactants using AuNPs-bioconjugates as optical-based molecular ruler and possible effects of AuNPs on microenvironment and conformations of the protein is presented.

Formation and biological effects of protein corona for food-related nanoparticles

The rapid development of nanoscience and nanoengineering provides new perspectives on the composition of food materials, and has great potential for food biology research and applications. The use of nanoparticle additives and the discovery of endogenous nanoparticles in food make it important to elucidate in vivo safety of nanomaterials. Nanoparticles will spontaneously adsorb proteins during transporting in blood and a protein corona can be formed on the nanoparticle surface inside the human body. Protein corona affects the physicochemical properties of nanoparticles and the structure and function of proteins, which in turn affects a series of biological reactions. This article reviewed basic information about protein corona of food-related nanoparticles, elucidated the influence of protein corona on nanoparticles properties and protein structure and function, and discussed the effect of protein corona on nanoparticles in vivo. The effects of protein corona on nanoparticles transport, cellular uptake, cytotoxicity, and immune response were reviewed, and the reasons for these effects were also discussed. Finally, future research perspectives for food protein corona were proposed. Protein corona gives food nanoparticles a new identity, which makes proteins bound to nanoparticles undergo structural transformations that affect their recognition by receptors in vivo. It can have positive or negative impacts on cellular uptake and toxicity of nanoparticles and even trigger immune responses. Understanding the effects of protein corona have potential in evaluating the fate of the food-related nanoparticles, providing physicochemical and biological information about the interaction between proteins and foodborne nanoparticles. The review article will help to evaluate the safety of protein coronas formed on nanoparticles in food, and may provide fundamental information for understanding and controlling nanotoxicity.

A three-tiered colloidosomal microreactor for continuous flow catalysis

Integrative colloidosomes with hierarchical structure and advanced function may serve as biomimetic microreactors to carry out catalytic reactions by compartmentalizing biological species within semipermeable membranes. Despite of recent progress in colloidosome design, integration of biological and inorganic components into tiered structures to tackle the remaining challenges of biocatalysis is highly demanded. Here, we report a rational design of three-tiered colloidosomes via the Pickering emulsion process. The microreactor consists of crosslinked amphiphilic silica-polymer hybrid nanoparticles as the semipermeable shell, an enzyme-incorporated catalytic sub-layer, and a partially-silicified adsorptive lumen. By leveraging confinement and enrichment effect, we demonstrate the acceleration of lipase-catalyzed ester hydrolysis within the microcompartment of organic-inorganic hybrid colloidosomes. The catalytic colloidosomes are further assembled into a closely packed column for enzymatic reactions in a continuous flow format with enhanced reaction rates. The three-tiered colloidosomes provide a reliable platform to integrate functional building blocks into a biomimetic compartmentalized microreactor with spatially controlled organization and high-performance functions.

Importance of Surface Topography in Both Biological Activity and Catalysis of Nanomaterials: Can Catalysis by Design Guide Safe by Design?

It is acknowledged that the physicochemical properties of nanomaterials (NMs) have an impact on their toxicity and, eventually, their pathogenicity. These properties may include the NMs’ surface chemical composition, size, shape, surface charge, surface area, and surface coating with ligands (which can carry different functional groups as well as proteins). Nanotopography, defined as the specific surface features at the nanoscopic scale, is not widely acknowledged as an important physicochemical property. It is known that the size and shape of NMs determine their nanotopography which, in turn, determines their surface area and their active sites. Nanotopography may also influence the extent of dissolution of NMs and their ability to adsorb atoms and molecules such as proteins. Consequently, the surface atoms (due to their nanotopography) can influence the orientation of proteins as well as their denaturation. However, although it is of great importance, the role of surface topography (nanotopography) in nanotoxicity is not much considered. Many of the issues that relate to nanotopography have much in common with the fundamental principles underlying classic catalysis. Although these were developed over many decades, there have been recent important and remarkable improvements in the development and study of catalysts. These have been brought about by new techniques that have allowed for study at the nanoscopic scale. Furthermore, the issue of quantum confinement by nanosized particles is now seen as an important issue in studying nanoparticles (NPs). In catalysis, the manipulation of a surface to create active surface sites that enhance interactions with external molecules and atoms has much in common with the interaction of NP surfaces with proteins, viruses, and bacteria with the same active surface sites of NMs. By reviewing the role that surface nanotopography plays in defining many of the NMs’ surface properties, it reveals the need for its consideration as an important physicochemical property in descriptive and predictive toxicology. Through the manipulation of surface topography, and by using principles developed in catalysis, it may also be possible to make safe-by-design NMs with a reduction of the surface properties which contribute to their toxicity.

Interplay between nanomedicine and protein corona

Nanomedicine is recognized as a promising agent for diverse biomedical applications; however, its safety and efficiency in clinical practice remains to be enhanced. A priority issue is the protein corona (PC), which imparts unique biological identities to prototype and determines the actual biological functions in biological fluids. Decades of work has already illuminated abundant considerations that influence the composition of the protein corona. Thereinto, the physical assets of nanomedicines (e.g., size and shape, surface properties, nanomaterials) and the biological environment collectively play fundamental roles in shaping the PC, including the types and quantities of plasma proteins. The properties of nanomedicines are dependent on certain factors. This review aims to explore the applications of nanomedicines by regulating their interplay with PC.

Identification and interaction mechanism of protein corona on silver nanoparticles with different sizes and the cellular responses

With the potential biomedical applications of nanomaterials such as silver nanoparticles (SNPs), nanotoxicity concerns are growing, and the importance of NP and protein interactions is far from being addressed enough. Here, we identified the major binding protein on SNPs in blood as human serum albumin (HSA) using polyacrylamide gel electrophoresis and liquid chromatography-mass spectrometry/mass spectrometry. By comparing with the previous methods, we emphasized surface area concentration as a new dose metric to address the importance of NP curvature. SNPs interacted with cysteine and cystine, disrupting the secondary structure and conformation of HSA, and this tendency became stronger on small SNPs than large ones. The protein corona significantly alleviated the toxicity and decreased SNPs' internalization in a particle size-dependent manner, where more significant inhibition effects occurred on larger particles at the same area concentration. These findings may shed light on nanotoxicity and also the design of safe nanomaterials by a comprehensive preconsideration of the metrological method.

Particulate Matter 2.5 and Hematological Disorders From Dust to Diseases: A Systematic Review of Available Evidence

Particulate matter 2.5 (PM_2.5) in the air enters the human body by diffusion into the blood. Therefore, hematological abnormalities might occur because of these toxic particles, but few studies on this issue have been reported. According to Cochrane guidance, we performed a systematic review on the relationship between exposure to PM_2.5 and the risk of hematological disorders. Ten articles were included in this review. Anemia was found among children and elderly populations with 2- to 5-year PM_2.5 exposure. Young children from mothers exposed to air pollution during pregnancy had a higher incidence of leukemia similar to the elderly. Supporting these data, outdoor workers also showed abnormal epigenetic modifications after exposure to very high PM_2.5 levels. Adults living in high PM_2.5 areas for 2 years were more likely to develop thrombocytosis. Finally, elderly populations with 7- to 8-year PM_2.5 exposure showed increased risks of venous thromboembolism. In conclusion, the associations between PM_2.5 and hematological aberrations among high-risk people with long-term exposure were reported.

Effect of gold nanoparticles on the structure and neuroprotective function of protein L-isoaspartyl methyltransferase (PIMT)

Fibrillation of peptides and proteins is implicated in various neurodegenerative diseases and is a global concern. Aging leads to the formation of abnormal isoaspartate (isoAsp) residues from isomerization of normal aspartates in proteins, triggering fibril formation that leads to neurodegenerative diseases. Protein L-isoaspartyl methyltransferase (PIMT) is a repair enzyme which recognizes and converts altered isoAsp residues back to normal aspartate. Here we report the effect of gold nanoparticles (AuNPs) of different sizes on the structure and function of PIMT. Spherical AuNPs, viz. AuNS5, AuNS50 and AuNS100 (the number indicating the diameter in nm) stabilize PIMT, with AuNS100 exhibiting the best efficacy, as evident from various biophysical experiments. Isothermal titration calorimetry (ITC) revealed endothermic, but entropy driven mode of binding of PIMT with all the three AuNSs. Methyltransferase activity assay showed enhanced activity of PIMT in presence of all AuNSs, the maximum being with AuNS100. The efficacy of PIMT in presence of AuNS100 was further demonstrated by the reduction of fibrillation of Aβ42, the peptide that is implicated in Alzheimer's disease. The enhancement of anti-fibrillation activity of PIMT with AuNS100 was confirmed from cell survival assay with PC12 derived neuronal cells against Aβ42 induced neurotoxicity.

Optimal centrifugal isolating of liposome-protein complexes from human plasma

In the past few years, characterization of the protein corona (PC) that forms around liposomal systems has gained increasing interest for the development of novel therapeutic and diagnostic technologies. At the crossroads of fast-moving research fields, the interdisciplinarity of protein corona investigations poses challenges for experimental design and reporting. Isolation of liposome-protein complexes from biological fluids has been identified as a fundamental step of the entire workflow of PC characterization but exact specifications for conditions to optimize pelleting remain elusive. In the present work, key factors affecting precipitation of liposome-protein complexes by centrifugation, including time of centrifugation, total sample volume, lipid : protein ratio and contamination from biological NPs were comprehensively evaluated. Here we show that the total amount of isolated liposome-protein complexes and the extent of contamination from biological NPs may vary with influence factors. Our results provide protein corona researchers with precise indications to separate liposome-protein complexes from protein-rich fluids and include proper controls, thus they are anticipated to catalyze improved consistency of data mining and computational modelling of protein corona composition.

Protein nanoparticles in drug delivery: animal protein, plant proteins and protein cages, albumin nanoparticles

In this article, we will describe the properties of albumin and its biological functions, types of sources that can be used to produce albumin nanoparticles, methods of producing albumin nanoparticles, its therapeutic applications and the importance of albumin nanoparticles in the production of pharmaceutical formulations. In view of the increasing use of Abraxane and its approval for use in the treatment of several types of cancer and during the final stages of clinical trials for other cancers, to evaluate it and compare its effectiveness with conventional non formulations of chemotherapy Paclitaxel is paid. In this article, we will examine the role and importance of animal proteins in Nano medicine and the various benefits of these biomolecules for the preparation of drug delivery carriers and the characteristics of plant protein Nano carriers and protein Nano cages and their potentials in diagnosis and treatment. Finally, the advantages and disadvantages of protein nanoparticles are mentioned, as well as the methods of production of albumin nanoparticles, its therapeutic applications and the importance of albumin nanoparticles in the production of pharmaceutical formulations.

Protein-nanoparticle interactions and a new insight

The study of protein-nanoparticle interactions provides knowledge about the bio-reactivity of nanoparticles, and creates a database of nanoparticles for applications in nanomedicine, nanodiagnosis, and nanotherapy. The problem arises when nanoparticles come in contact with physiological fluids such as plasma or serum, wherein they interact with the proteins (or other biomolecules). This interaction leads to the coating of proteins on the nanoparticle surface, mostly due to the electrostatic interaction, called 'corona'. These proteins are usually partially unfolded. The protein corona can deter nanoparticles from their targeted functionalities, such as drug/DNA delivery at the site and fluorescence tagging of diseased tissues. The protein corona also has many repercussions on cellular intake, inflammation, accumulation, degradation, and clearance of the nanoparticles from the body depending on the exposed part of the proteins. Hence, the protein-nanoparticle interaction and the configuration of the bound-proteins on the nanosurface need thorough investigation and understanding. Several techniques such as DLS and zeta potential measurement, UV-vis spectroscopy, fluorescence spectroscopy, circular dichroism, FTIR, and DSC provide valuable information in the protein-nanoparticle interaction study. Besides, theoretical simulations also provide additional understanding. Despite a lot of research publications, the fundamental question remained unresolved. Can we aim for the application of functional nanoparticles in medicine? A new insight, given by us, in this article assumes a reasonable solution to this crucial question.