Effect of Functionalized Magnetic MnFe2O4 Nanoparticles on Fibrillation of Human Serum Albumin

Molecular insights into the phase transition of lysozyme into amyloid nanostructures: Implications of therapeutic strategies in diverse pathological conditions

Lysozyme, a well-known bacteriolytic enzyme, exhibits a fascinating yet complex behavior when it comes to protein aggregation. Under certain conditions, this enzyme undergoes flexible transformation, transitioning from partially unfolded intermediate units of native conformers into complex cross-β-rich nano fibrillar amyloid architectures. Formation of such lysozyme amyloids has been implicated in a multitude of pathological and medical severities, like hepatic dysfunction, hepatomegaly, splenic rupture as well as spleen dysfunction, nephropathy, sicca syndrome, renal dysfunction, renal amyloidosis, and systemic amyloidosis. In this comprehensive review, we have attempted to provide in-depth insights into the aggregating behavior of lysozyme across a spectrum of variables, including concentrations, temperatures, pH levels, and mutations. Our objective is to elucidate the underlying mechanisms that govern lysozyme's aggregation process and to unravel the complex interplay between its structural attributes. Moreover, this work has critically examined the latest advancements in the field, focusing specifically on novel strategies and systems, that have been implemented to delay or inhibit the lysozyme amyloidogenesis. Apart from this, we have tried to explore and advance our fundamental understanding of the complex processes involved in lysozyme aggregation. This will help the research community to lay a robust foundation for screening, designing, and formulating targeted anti-amyloid therapeutics offering improved treatment modalities and interventions not only for lysozyme-linked amyloidopathy but for a wide range of amyloid-related disorders.

Targeting Amyloids with Coated Nanoparticles: A Review on Potential Combinations of Nanoparticles and Bio-Compatible Coatings

Amyloidosis is the major cause of many neurodegenerative diseases, such as, Alzheimer's and Parkinson's where the misfolding and deposition of a previously functional protein make it inept for carrying out its function. The genesis of amyloid fibril formation and the strategies to inhibit it have been studied extensively, although some parts of this puzzle still remain unfathomable to date. Many classes of molecules have been explored as potential drugs in vitro, but their inability to work in vivo by crossing the blood-brain-barrier has made them an inadequate treatment option. In this regard, nanoparticles (NPs) have turned out to be an exciting alternative because they could overcome many drawbacks of previously studied molecules and provide advantages, such as, greater bioavailability of molecules and target-specific delivery of drugs. In this paper, we present an overview on several coated NPs which have shown promising efficiency in inhibiting fibril formation. A hundred and thirty papers published in the past two decades have been comprehensively reviewed, which majorly encompass NPs comprising different materials like gold, silver, iron-oxide, poly(lactic-co-glycolic acid), polymeric NP, etc., which are coated with various molecules of predominantly natural origin, such as different types of amino acids, peptides, curcumin, drugs, catechin, etc. We hope that this review will shed light on the advancement of symbiotic amalgamation of NPs with molecules from natural sources and will inspire further research on the tremendous therapeutic potential of these combinations for many amyloid-related diseases.

Inhibitory effect of plain and functionalized graphene nanoplateles on hen egg white lysozyme fibrillation

Protein fibrillation is a phenomenon associated with misfolding and the production of highly ordered nanofibrils, which may cause serious degenerative diseases such as Parkinson's disease, Alzheimer's disease, and type 2 diabetes. Upon contact with biological fluids, the nanomaterials are immediately covered by proteins and interact with them. In this study, the effects of Graphene NanoPlateles (Plain-GNPs) and their modified forms with a carboxyl group (GNPs -COOH) and an amine group (GNPs -NH2) are evaluated on the fibrillation process of Hen Egg White Lysozyme (HEWL). The fibrillation process of HEWL was studied using thioflavin-T, Circular Dichroism spectrometry, and Atomic Force Microscopy. Plain-GNPs significantly decreased the fibrillation process at different stages, including nucleation, exponential fibrillation phases, and end-mature fibril products. However, GNPs-COOH and GNPs-NH2 affected the final fluorescence of ThT. The species formed in the presence of Plain-GNPs showed less toxicity in SH-SY5Y cells, which could be applicable for therapeutic purposes.

Novel Biocompatible Magnetoelectric MnFe2 O4 Core@BCZT Shell Nano-Hetero-Structures with Efficient Catalytic Performance

Magnetoelectric (ME) small-scale robotic devices attract great interest from the scientific community due to their unique properties for biomedical applications. Here, novel ME nano hetero-structures based on the biocompatible magnetostrictive MnFe2 O4 (MFO) and ferroelectric Ba0.85 Ca0.15 Zr0.1 Ti0.9 O3 (BCZT) are developed solely via the hydrothermal method for the first time. An increase in the temperature and duration of the hydrothermal synthesis results in increasing the size, improving the purity, and inducing morphology changes of MFO nanoparticles (NPs). A successful formation of a thin epitaxial BCZT-shell with a 2-5 nm thickness is confirmed on the MFO NPs (77 ± 14 nm) preliminarily treated with oleic acid (OA) or polyvinylpyrrolidone (PVP), whereas no shell is revealed on the surface of pristine MFO NPs. High magnetization is revealed for the developed ME NPs based on PVP- and OA-functionalized MFO NPs (18.68 ± 0.13 and 20.74 ± 0.22 emu g-1 , respectively). Moreover, ME NPs demonstrate 95% degradation of a model pollutant Rhodamine B within 2.5 h under an external AC magnetic field (150 mT, 100 Hz). Thus, the developed biocompatible core-shell ME NPs of MFO and BCZT can be considered as a promising tool for non-invasive biomedical applications, environmental remediation, and hydrogen generation for renewable energy sources.

A Review of the Use of Metallic Nanoparticles as a Novel Approach for Overcoming the Stability Challenges of Blood Products: A Narrative Review from 2011-2021

PURPOSE

To obtain safe and qualified blood products (e.g., platelets, plasma, and red blood cells), various limitations such as limited shelf life (especially for platelets) and stability must be addressed. In this review study, the most commonly used metal nanomaterials (e.g., gold, silver, iron, and magnetic) reported in the literature from 2011 to 2021 were discussed owing to their unique properties, which provide exciting approaches to overcome these limitations and improve the stability, safety, and quality of blood products. Novelty: This study reviews for the first time the results of studies (from 2011 to 2021) that consider the effects of various metallic nanoparticles on the different blood products.

RESULTS

The results of this review study showed that some metallic nanoparticles are effective in improving the stability of plasma proteins. For this purpose, modified Fe₃O₄ magnetic nanoparticles and citrate-AuNPs protect albumin products against stressful situations. Also, SiO₂ microspheres and silicacoated magnetite nanoparticles are highly capable of improving IgG stability. ZnO nanoparticles also reduced thrombin production, and protein-coated GMNP nanoparticles prevented unwanted leakage of factor VIII through blood vessels. Furthermore, the stability and longevity of erythrocytes can be improved by AuNP nanoparticles and Zr-based organic nanoparticles. In addition, platelet storage time can be improved using PEGylated Au and functionalized iron oxide nanoparticles.

SUGGESTION

According to the results of this study, it is suggested that further research should be conducted on metal nanoparticles as the most promising candidates to prepare metal nanoparticles with improved properties to increase the stability of various blood products.

Investigation on conformational variation and fibrillation of human serum albumin affected by molybdenum disulfide quantum dots

In this work, binding interaction between molybdenum disulfide quantum dots (MoS₂ QDs) and human serum albumin (HSA) was researched deeply to dissect the conformational variation and fibrillation of HSA affected by MoS₂ QDs. The results revealed that MoS₂ QDs bound strongly with HSA with molar ratio of 1:1 under the joint actions of hydrogen bond and van der Waals force, leading to the static fluorescence quenching of HSA. MoS₂ QDs caused the secondary structure transition of HSA from α-helix stepwise to β-turn, β-sheet, and random coil gradually. MoS₂ QDs reduced both the molar enthalpy change and the melting temperature of HSA, reducing the thermal stability of HSA significantly. It is worth noting that MoS₂ QDs inhibited the fibrillation process of HSA according to the reduced hydrophobic environment and the disturbance of disulfide bonds in HSA network structure. These results reveal the precise binding mechanism of MoS₂ QDs with HSA at molecular level, providing indispensable information for the potential application of MoS₂ QDs in biological fields.

Surface-modified magnetite nanoparticles affect lysozyme amyloid fibrillization

BACKGROUND

The surface of nanoparticles (NPs) is an important factor affecting the process of poly/peptides' amyloid aggregation. We have investigated the in vitro effect of trisodium citrate (TC), gum arabic (GA) and citric acid (CA) surface-modified magnetite nanoparticles (COAT-MNPs) on hen egg-white lysozyme (HEWL) amyloid fibrillization and mature HEWL fibrils.

METHODS

Dynamic light scattering (DLS) was used to characterize the physico-chemical properties of studied COAT-MNPs and determine the adsorption potential of their surface towards HEWL. The anti-amyloid properties were studied using thioflavin T (ThT) and tryptophan (Trp) intrinsic fluorescence assays, and atomic force microscopy (AFM). The morphology of amyloid aggregates was analyzed using Gwyddion software. The cytotoxicity of COAT-MNPs was determined utilizing Trypan blue (TB) assay.

RESULTS

Agents used for surface modification affect the COAT-MNPs physico-chemical properties and modulate their anti-amyloid potential. The results from ThT and intrinsic fluorescence showed that the inhibitory activities result from the more favorable interactions of COAT-MNPs with early pre-amyloid species, presumably reducing nuclei and oligomers formation necessary for amyloid fibrillization. COAT-MNPs also possess destroying potential, which is presumably caused by the interaction with hydrophobic residues of the fibrils, resulting in the interruption of an interface between β-sheets stabilizing the amyloid fibrils.

CONCLUSION

COAT-MNPs were able to inhibit HEWL fibrillization and destroy mature fibrils with different efficacy depending on their properties, TC-MNPs being the most potent nanoparticles.

GENERAL SIGNIFICANCE

The study reports findings regarding the general impact of nanoparticles' surface modifications on the amyloid aggregation of proteins.

Human Serum Albumin in the Presence of AGuIX Nanoagents: Structure Stabilisation without Direct Interaction

The gadolinium-based nanoagent named AGuIX^® is a unique radiosensitizer and contrast agent which improves the performance of radiotherapy and medical imaging. Currently tested in clinical trials, AGuIX^® is administrated to patients via intravenous injection. The presence of nanoparticles in the blood stream may induce harmful effects due to undesired interactions with blood components. Thus, there is an emerging need to understand the impact of these nanoagents when meeting blood proteins. In this work, the influence of nanoagents on the structure and stability of the most abundant blood protein, human serum albumin, is presented. Synchrotron radiation circular dichroism showed that AGuIX^® does not bind to the protein, even at the high ratio of 45 nanoparticles per protein at 3 mg/L. However, it increases the stability of the albumin. Isothermal thermodynamic calorimetry and fluorescence emission spectroscopy demonstrated that the effect is due to preferential hydration processes. Thus, this study confirms that intravenous injection of AGuIX^® presents limited risks of perturbing the blood stream. In a wider view, the methodology developed in this work may be applied to rapidly evaluate the impact and risk of other nano-products that could come into contact with the bloodstream.

Interaction of ZnO Nanostructures with Proteins: In Vitro Fibrillation/Antifibrillation Studies and in Silico Molecular Docking Simulations

Protein amyloidosis is related to many neurological disorders. Nanoparticles (NPs) due to their small size can regulate both the polypeptide monomers/oligomers assembly into amyloid fibrils/plaques and the disintegration of the existent plaques. Herein, we have synthesized ZnO nanoflowers and polyol-coated ZnO NPs of relatively small size (40 nm) with cylindrical shape, through solvothermal and microwave-assisted routes, respectively. The effect of the different morphology of nanostructures on the fibrillation/antifibrillation process was monitored in bovine serum albumin (BSA) and human insulin (HI) by fluorescence Thioflavin T (ThT) measurements. Although both nanomaterials affected the amyloid formation mechanism as well as their disaggregation, ZnO nanoflowers with their sharp edges exhibited the greatest amyloid degradation rate in both model proteins (73% and 35%, respectively) and inhibited the most the insulin fibril growth, while restrained also the fibrillation process in the case of albumin solution. In silico molecular docking simulations on the crystal structure of BSA and HI were performed to analyze further the observed in vitro activity of ZnO nanostructures. The binding energy of ZnO NPs was found lower for BSA (-5.44), highlighting their ability to act as catalysts in the fibrillation process of albumin monomers.

Effect of albumin mediated clustering on the magnetic behavior of MnFe2O4 nanoparticles: experimental and theoretical modeling study

Over the last two decades, iron oxide based nanoparticles ferrofluids have attracted significant attention for a wide range of applications. For the successful use of these materials in biotechnology and energy, surface coating and specific functionalization is critical to achieve high dispersibility and colloidal stability of the nanoparticles in the ferrofluids. In view of this, the magnetic behavior of clusters of ultra-small MnFe₂O₄ nanoparticles covered by bovine serum albumin, which is known as a highly biocompatible and environmentally friendly surfactant, is investigated by magnetization measurements, and numerical simulations at an atomic and mesoscopic scale. The coating process with albumin produces a change in the structure, actual size and shape distribution of clusters of exchange coupled particles, giving rise to a distribution of blocking temperatures. The coated system exhibits a superspin glass (SSG) behavior with the SSG freezing temperatures similar to the uncoated ones, providing evidence that the strength of the dipolar interactions is not affected by the presence of the albumin. The DFT calculations show that the albumin coating reduces the surface anisotropy and the saturation magnetization in the nanoparticles leading to lower values of the coercive field in agreement with the experimental findings. Our results clearly demonstrate that the albumin coated clusters of MnFe₂O₄ particles are ideal systems for energy and biomedical applications since colloidal and thermal stability as well as biosafety is obtained through the albumin coating.

Inhibition of Amyloid Fibrillation by Small Molecules and Nanomaterials: Strategic Development of Pharmaceuticals Against Amyloidosis

Amyloid fibrils are a special class of self-assembled protein molecules, which exhibit various toxic effects in cells. Different physiological disorders such as Alzheimer's, Parkinson's, Huntington's diseases, etc. happen due to amyloid formation and lack of proper cellular mechanism for the removal of fibrils. Therefore, inhibition of amyloid fibrillation will find immense applications to combat the diseases associated with amyloidosis. The development of therapeutics against amyloidosis is definitely challenging and numerous strategies have been followed to find out anti-amyloidogenic molecules. Inhibition of amyloid aggregation of proteins can be achieved either by stabilizing the native conformation or by decreasing the chances of assembly formation by the unfolded/misfolded structures. Various small molecules such as naturally occurring polyphenols, flavonoids, small organic molecules, surfactants, dyes, chaperones, etc. have demonstrated their capability to interrupt the amyloid fibrillation of proteins. In addition to that, in last few years, different nanomaterials were evolved as effective therapeutic inhibitors against amyloidosis. Aromatic and hydrophobic interactions between the partially unfolded protein molecules and the inhibitors had been pointed as a general mechanism for inhibition. In this review article, we are presenting an overview on the inhibition of amyloidosis by using different small molecules (both natural and synthetic origin) as well as nanomaterials for development of pharmaceutical strategies against amyloid diseases.

Inhibition of Glycation-Induced Aggregation of Human Serum Albumin by Organic-Inorganic Hybrid Nanocomposites of Iron Oxide-Functionalized Nanocellulose

Protein aggregation leads to the transformation of proteins from their soluble form to the insoluble amyloid fibrils and these aggregates get deposited in the specific body tissues, accounting for various diseases. To prevent such an aggregation, organic-inorganic hybrid nanocomposites of iron oxide nanoparticle (NP, ∼6.5-7.0 nm)-conjugated cellulose nanocrystals (CNCs) isolated from Syzygium cumini (SC) and Pinus roxburghii (PR) were chemically synthesized. Transmission electron microscopy (TEM) images of the nanocomposites suggested that the in situ-synthesized iron oxide NPs were bound to the CNC surface in a uniform and regular fashion. The ThT fluorescence assay together with 8-anilino-1-naphthalenesulfonic acid, Congo Red, and CD studies suggested that short fiber-based SC nanocomposites showed better inhibition as well as dissociation of human serum albumin aggregates. The TEM and fluorescence microscopy studies supported similar observations. Native polyacrylamide gel electrophoresis results documented dissociation of higher protein aggregates in the presence of the developed nanocomposite. Interestingly, the dissociated proteins retained their biological function by maintaining a high amount of α-helix content. The in vitro studies with HEK-293 cells suggested that the developed nanocomposite reduces aggregation-induced cytotoxicity by intracellular reactive oxygen species scavenging and maintaining the Ca2+ ion-channel. These results indicated that the hybrid organic-inorganic nanocomposite, with simultaneous sites for hydrophobic and hydrophilic interactions, tends to provide a larger surface area for nanocomposite-protein interactions, which ultimately disfavors the nucleation step for fibrillation for protein aggregates.

Interplay between Amyloid Fibrillation Delay and Degradation by Magnetic Zinc-Doped Ferrite Nanoparticles

Amyloidosis, the aggregation of naturally soluble proteins into fibrils, is the main pathological hallmark of central nervous system (CNS) disorders, and new therapeutic approaches can be introduced through nanotechnology. Herein, magnetic nanoparticles (MNPs) are proposed to combat amyloidosis and act as CNS theranostic (therapy and diagnosis) candidates through magnetomechanical forces that can be induced under a low-frequency magnetic field. In that vein, a modified one-step microwave-assisted polyol process has been employed to synthesize hybrid organic/inorganic zinc ferrite (Zn_xFe_3-xO₄) MNPs with different levels of zinc doping (0.30 < x < 0.6) derived from the utilized polyol. The lowest doped (x = 0.30) MNPs exhibited high magnetization (127 emu/g), high T₂ imaging ability (r₂ = 432 mM^-1 s^-1), and relatively small hydrodynamic size (180 nm), decisive characteristics to further evaluate their CNS theranostic potential. Their effect on the fibrillation/degradation was monitored in two model proteins, insulin and albumin, in the presence/absence of variant external magnetic fields (static, rotating, or alternating) via Thioflavin T (ThT) fluorescence assay and optical fluorescence microscopy. The MNPs were injected either in oligomer solution where significant fibrillation delay was observed, boosted by zinc ionic leaching of MNPs, or in already formed amyloid plaques where up to 86% amyloid degradation was recorded in the presence of magnetic fields, unveiling magnetomechanical antifibrillation properties. The alternating magnetic field (4 Hz) allows the bouncing of the MNPs into the amyloid net driven by the magnetic forces, and thus is featured as the preferred "dancing mode", which strengthens the degrading efficacy of MNPs.

Self-assembly of plant protein fibrils interacting with superparamagnetic iron oxide nanoparticles

In situ fibrillation of plant proteins in presence of the superparamagnetic iron oxide nanoparticles (NP) promoted formation of a hybrid nanocomposite. The morphology of NP-fibril composite was revealed using ex-situ atomic force microscopy (AFM) in air. The NP-fibrils were associated into extended multi-fibril structures, indicating that the addition of NPs promoted protein association via β-sheet assembly. Real-time movement of NPs attached to fibrils under an external magnetic field was visualized using in-situ AFM in liquid, revealing that composite structures were stable at low pH, and displaying dipolar property of the NPs in the composite at high pH. Changes in magnetic properties of NPs when interacting with protein fibrils were quantitatively mapped using magnetic force microscopy (MFM). The magnetic moment of the NPs in composite was increased by co-existing with protein at low pH, while their dipolar nature was maintained at high pH. Self-assembly of the protein into fibrils is accelerated with increasing NP concentration within an optimal range, which is attributed to a fibrillation-competent conformation of the peptides. The latter was explained by the formation of favorable hydrogen bonds, electrostatic interactions, and efficient surface energy transfer between NPs and proteins.

Effect of negative functionalisation of gold nanorods on conformation and activity of human serum albumin

The theranostic applications of gold nanorods (AuNRs) are limited due to the presence of cytotoxic cetrimonium bromide (CTAB) stabiliser, leading to the instigation of alternate stabilisers like negatively charged polystyrene sulphonate (PSS). Despite previous reports suggesting the impact of PSS‐AuNRs on cells, their effect on the most abundant protein in plasma, i.e. human serum albumin (HSA), has not been studied before. Hence, the impact of PSS‐AuNRs on HSA was thoroughly examined using varied spectroscopic techniques. The absorbance and fluorescence spectroscopic findings suggested the extent of ground‐state complexation and tryptophan domain disruptions of HSA for different AuNR concentrations, which were also suggested based on size measurements and activation energy calculations for complex formation. Modifications in the hydrophobic environment of HSA were evaluated using synchronous fluorescence, whereas the secondary structural damages were explained using circular dichroism (CD) and FTIR analyses. Additional studies to analyse protein denaturation, fibrillation, esterase activity, and free thiol were carried out to understand structural and functional changes. The study suggested that PSS‐AuNRs showed concentration‐dependent alterations in HSA structure, but the extent of protein toxicity was considerably lesser for PSS‐AuNRs of similar dimensions compared to the data available for CTAB‐AuNRs; thus, highlighting that PSS‐AuNRs could be safer for biomedical applications.

Impact of nanoparticles on amyloid peptide and protein aggregation: a review with a focus on gold nanoparticles

Society is increasingly exposed to nanoparticles as they are ubiquitous in nature and introduced as man-made air pollutants and as functional ingredients in cosmetic products as well as in nanomedicine. Nanoparticles differ in size, shape and material properties. In addition to their intended function, the side effects on biochemical processes in organisms remain unclear. Nanoparticles can significantly influence the nucleation and aggregation process of peptides. The development of several neurodegenerative diseases, such as Alzheimer's disease, is related to the aggregation of peptides into amyloid fibrils. However, there is no comprehensive or universal mechanism to predict or explain apparent acceleration or inhibition of these aggregation processes. In this work, selected studies and possible mechanisms for amyloid peptide nucleation and aggregation, in the presence of nanoparticles, are highlighted. These studies are discussed in the context of recent data from our group on the role of gold nanoparticles in amyloid peptide aggregation using experimental methods and large-scale molecular dynamics simulations. A complex interplay of the surface properties of the nanoparticles, the properties of the peptides, as well as the resulting forces between both the nanoparticles and the peptides, appear to determine whether amyloid peptide aggregation is influenced, catalysed or inhibited by the presence of nanoparticles.

Label Free Ultrasmall Fluoromagnetic Ferrite-clusters for Targeted Cancer Imaging and Drug Delivery

OBJECTIVE

The label free ultrasmall fluorescent ferrite clusters have been engineered in a controlled fashion which was stabilized by serum protein and functionalized by folic acid for the application of targeted multimodal optical and Magnetic Resonance (MR) cancer imaging.

METHODS

The ultra-small manganese ferrite nanoclusters (PMNCs) with a diameter of 4 nm have a commendable effect on the longitudinal (T1) and transverse (T2) relaxation in MR imaging that was evident from the phantom and animal MRI.

RESULTS

The calculated longitudinal molar relaxivity of nanoclusters was found to be 6.9 ± 0.10 mM-1 S-1 which was exactly 2.22 times better than the conventional Gd-DOTA and their 4.01 ratio of the transverse (r2) and longitudinal (r1) relaxivities made them a potential candidate for both T1 and T2 contrast agents in MRI. In addition, the fluorescence-based small animal imaging showed folic acid driven accumulated fluorescent signal at the tumour site to conclude the capacity of PMNCs for targeted fluorescence imaging of cancer diagnosis.

CONCLUSION

The cytotoxicity assay and histopathology studies were the evidence for their safe biodistribution in animal systems. Furthermore, the protein encapsulated clusters have the ability to deliver the anticancer drug Methotrexate (MTX) to the cancer tissues with a sustained manner. Therefore, one can conclude the remarkable efficacy of architect nanoclusters for theragnosis.

Magnetic Nanoparticles Applications for Amyloidosis Study and Detection: A Review

Magnetic nanoparticles (MNPs) have great potential in biomedical and clinical applications because of their many unique properties. This contribution provides an overview of the MNPs mainly used in the field of amyloid diseases. The first part discusses their use in understanding the amyloid mechanisms of fibrillation, with emphasis on their ability to control aggregation of amyloidogenic proteins. The second part deals with the functionalization by various moieties of numerous MNPs’ surfaces (molecules, peptides, antibody fragments, or whole antibodies of MNPs) for the detection and the quantification of amyloid aggregates. The last part of this review focuses on the use of MNPs for magnetic-resonance-based amyloid imaging in biomedical fields, with particular attention to the application of gadolinium-based paramagnetic nanoparticles (AGuIX), which have been recently developed. Biocompatible AGuIX nanoparticles show favorable characteristics for in vivo use, such as nanometric and straightforward functionalization. Their properties have enabled their application in MRI. Here, we report that AGuIX nanoparticles grafted with the Pittsburgh compound B can actively target amyloid aggregates in the brain, beyond the blood–brain barrier, and remain the first step in observing amyloid plaques in a mouse model of Alzheimer’s disease.

Morphological Effects of CuO Nanostructures on Fibrillation of Human Serum Albumin

The influence of different morphologies of nanostructures on amyloid fibrillation has been investigated by monitoring the fibrillation of human serum albumin (HSA) in the presence of rod-, sphere-, flower-, and star-shaped copper oxide (CuO) nanostructures. The different morphologies of CuO have been synthesized from an aqueous solution-based precipitation method using various organic acids, viz., acetic acid, citric acid, and tartaric acid. The fibrillation process of HSA has been examined using various biophysical techniques, e.g., Thioflavin T fluorescence, Congo red binding studies through UV spectroscopy, circular dichroism spectroscopy, and fluorescence microscopy. The monolayer protein coverage on the CuO nanostructures has been established through DLS studies, and the well-fitted Langmuir isotherm model has been used to interpret the differential adsorption behavior of HSA molecules on the CuO nanostructures. The nanostar-shaped CuO, by virtue of their higher specific surface area (94.45 m² g^-1), presence of high indexed facets {211} and high positive surface charge potential (+16.2 mV at pH 7.0) was found to show the highest adsorption of the HSA monomers and thus was more competent to inhibit the formation of HSA fibrils compared to the other nanostructures of CuO.

Influence of gold nanoparticle surface chemistry and diameter upon Alzheimer's disease amyloid-β protein aggregation

Background

Deposits of aggregated amyloid-β protein (Aβ) are a pathological hallmark of Alzheimer’s disease (AD). Thus, one therapeutic strategy is to eliminate these deposits by halting Aβ aggregation. While a variety of possible aggregation inhibitors have been explored, only nanoparticles (NPs) exhibit promise at low substoichiometric ratios. With tunable size, shape, and surface properties, NPs present an ideal platform for rationally designed Aβ aggregation inhibitors. In this study, we characterized the inhibitory capabilities of gold nanospheres exhibiting different surface coatings and diameters.

Results

Both NP diameter and surface chemistry were found to modulate the extent of aggregation, while NP electric charge influenced aggregate morphology. Notably, 8 nm and 18 nm poly(acrylic acid)-coated NPs abrogated Aβ aggregation at a substoichiometric ratio of 1:2,000,000. Theoretical calculations suggest that this low stoichiometry could arise from altered solution conditions near the NP surface. Specifically, local solution pH and charge density are congruent with conditions that influence aggregation.

Conclusions

These findings demonstrate the potential of surface-coated gold nanospheres to serve as tunable therapeutic agents for the inhibition of Aβ aggregation. Insights gained into the physiochemical properties of effective NP inhibitors will inform future rational design of effective NP-based therapeutics for AD.

Electronic supplementary material

The online version of this article (doi:10.1186/s13036-017-0047-6) contains supplementary material, which is available to authorized users.

Fabrication of a novel hollow fiber membrane decorated with functionalized Fe2O3 nanoparticles: towards sustainable water treatment and biofouling control

We explored a new strategy using well dispersed functionalized Fe₂O₃ nanoparticles to fabricate a polyetherimide nanocomposite hollow fiber membrane with enhanced surface and anti-biofouling properties.

Solvothermal fabrication and growth behavior study of spherical MnFe2O4 through a bottom-up method on wood substrate with effective microwave absorption

Spherical MnFe₂O₄ colloidal nanocrystal assemblies (CNAs) with different sizes were controllably fabricated on a wood substrate using a solvothermal method through a bottom-up pathway.

Inhibition of fibrillation of human serum albumin through interaction with chitosan-based biocompatible silver nanoparticles

Electrostatic interaction of chitosan-based silver nanoparticles with human serum albumin leads to inhibition of fibrillogenesis.

In Vivo Biomolecule Corona around Blood-Circulating, Clinically Used and Antibody-Targeted Lipid Bilayer Nanoscale Vesicles

The adsorption of proteins and their layering onto nanoparticle surfaces has been called the "protein corona". This dynamic process of protein adsorption has been extensively studied following in vitro incubation of many different nanoparticles with plasma proteins. However, the formation of protein corona under dynamic, in vivo conditions remains largely unexplored. Extrapolation of in vitro formed protein coronas to predict the fate and possible toxicological burden from nanoparticles in vivo is of great interest. However, complete lack of such direct comparisons for clinically used nanoparticles makes the study of in vitro and in vivo formed protein coronas of great importance. Our aim was to study the in vivo protein corona formed onto intravenously injected, clinically used liposomes, based on the composition of the PEGylated liposomal formulation that constitutes the anticancer agent Doxil. The formation of in vivo protein corona was determined after the recovery of the liposomes from the blood circulation of CD-1 mice 10 min postinjection. In comparison, in vitro protein corona was formed by the incubation of liposomes in CD-1 mouse plasma. In vivo and in vitro formed protein coronas were compared in terms of morphology, composition and cellular internalization. The protein coronas on bare (non-PEGylated) and monoclonal antibody (IgG) targeted liposomes of the same lipid composition were also comparatively investigated. A network of linear fibrillary structures constituted the in vitro formed protein corona, whereas the in vivo corona had a different morphology but did not appear to coat the liposome surface entirely. Even though the total amount of protein attached on circulating liposomes correlated with that observed from in vitro incubations, the variety of molecular species in the in vivo corona were considerably wider. Both in vitro and in vivo formed protein coronas were found to significantly reduce receptor binding and cellular internalization of antibody-conjugated liposomes; however, the in vivo corona formation did not lead to complete ablation of their targeting capability.