Proline functionalized gold nanoparticles modulates lysozyme fibrillation

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.

Amyloid β-Peptide Segment Conjugated Side-Chain Proline-Based Polymers as Potent Inhibitors in Lysozyme Amyloidosis

Developing effective amyloidosis inhibitors poses a significant challenge due to the dynamic nature of the protein structures, the complex interplay of interfaces in protein-protein interactions, and the irreversible nature of amyloid assembly. The interactions of amyloidogenic polypeptides with other peptides play a pivotal role in modulating amyloidosis and fibril formation. This study presents a novel approach for designing and synthesizing amyloid interaction surfaces using segments derived from the amyloid-promoting sequence of amyloid β-peptide [VF(Aβ(18-19)/FF(Aβ(19-20)/LVF(Aβ(17-19)/LVFF(Aβ(17-20)], where VF, FF, LVF and LVFF stands for valine phenylalanine dipeptide, phenylalanine phenylalanine dipeptide, leucine valine phenylalanine tripeptide and leucine valine phenylalanine phenylalanine tetrapeptide, respectively. These segments are conjugated with side-chain proline-based methacrylate polymers serving as potent lysozyme amyloidosis inhibitors and demonstrating reduced cytotoxicity of amyloid aggregations. Di-, tri-, and tetra-peptide conjugated chain transfer agents (CTAs) were synthesized and used for the reversible addition-fragmentation chain transfer polymerization of tert-butoxycarbonyl (Boc)-proline methacryloyloxyethyl ester (Boc-Pro-HEMA). Deprotection of Boc-groups from the side-chain proline pendants resulted in water-soluble polymers with defined peptide chain ends as peptide-polymer bioconjugates. Among them, the LVFF-conjugated polymer acted as a potent inhibitor with significantly suppressed lysozyme amyloidosis, a finding supported by comprehensive spectroscopic, microscopic, and computational analyses. These results unveil the synergistic effect between the segment-derived amyloid β-peptide and side-chain proline-based polymers, offering new prospects for targeting lysozyme amyloidosis.

Impedance nanobiosensor based on enzyme-conjugated biosynthesized gold nanoparticles for the detection of Gram-positive bacteria

In this report, gold nanoparticles (GNPS) were synthesized using cell-free extracts of seven different isolates, namely, Pseudomonas aerogenosa CEBP2, Pseudomonas sp. CEBP1, Pseudomonas pseudoalcaligenes CEB1G, Acinetobactor baumani CEBS1, Cuprividus sp. CEB3, Micrococcus luteus CUB12, and Pandoraea sp. CUB2S. The spectroscopic (UV-vis, FTIR, DLS, XRD, EDS) and microscopic (FESEM, TEM) results confirm the reduction of Au3+ to Au0 in the presence of biomolecules having reducing as well as self-stabilizing activity. In this green synthesis approach, the average particle size of biosynthesized GNPS might vary (4-60 nm) depending on the bacterial species, pH of the media, incubation time, and temperature. In this study, GSH-modified BSGNPs (Au-GSH) have shown antimicrobial activity with better stability against Gram-positive bacteria. After conjugation of lysozyme with Au-GSH (lyso@Au-GSH), the zone of inhibition was enhanced from 12 to 23 mm (Au-GSH). The TEM study shows the spherical GNP (16.65 ± 2.84) turns into a flower-shaped GNP (22.22 ± 3.12) after conjugation with lysozyme due to the formation of the protein corona. Furthermore, the nanobioconjugate (lyso@Au-GSH) was immobilized with Nafion on a glassy carbon electrode to fabricate a label-free impedance biosensor that is highly sensitive to monitor changes in the transducer surface due to biomolecular interactions. The uniquely designed biosensor could selectively detect Gram-positive bacteria in the linear range of 3.0 × 101-3 × 1010 cfu mL-1 with RE <5%. The proposed simplest biosensor exhibited good reproducibility (RSD = 3.1%) and excellent correlation (R2 = 0.999) with the standard plate count method, making it suitable for monitoring Gram-positive bacterial contamination in biofluids, food, and environmental samples.

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.

The impact of modified polystyrene on lysozyme fibrillation studied by surface-enhanced Raman spectroscopy (SERS)

Nanoplastics could modulate the fibrillation of amyloid proteins. However, many chemical functional groups are adsorbed to change the interfacial chemistry of nanoplastics in the real world. Herein, this study aimed to investigate the effects of polystyrene (PS), carboxyl modified PS (PS-COOH), and amino modified PS (PS-NH₂) on the fibrillation of hen egg-white lysozyme (HEWL). Due to the differences in the interfacial chemistry, concentration was considered an essential factor. PS-NH₂ (10 μg/mL) could promote the fibrillation of HEWL similar to PS (50 μg/mL) and PS-COOH (50 μg/mL). Moreover, promoting the primary nucleation step of amyloid fibril formation was the primary reason. The differences in spatial conformation of HEWL were characterized by Fourier transform-infrared spectroscopy and surface enhanced Raman spectroscopy (SERS). Strikingly, a particular signal of SERS of HEWL incubated with PS-NH₂ at 1610 cm^-1 was found due to the interaction between amino group of PS-NH₂ and tryptophan (or tyrosine) of HEWL. Therefore, a new perspective was provided to understand the regulation of interfacial chemistry of nanoplastics on the fibrillation of amyloid proteins. Additionally, this study suggested that SERS could be a powerful method to investigate the interactions between proteins and nanoparticles.

The Effect of Trehalose Coating for Magnetite Nanoparticles on Stability of Egg White Lysozyme

In this study, the protein stability of hen egg-white lysozymes (HEWL) by Fe₃O₄ and Fe₃O₄-coated trehalose (Fe₃O₄@Tre) magnetic nanoparticles (NPs) is investigated. For this purpose, the co-precipitation method was used to synthesize magnetic NPs. The synthesized NPs were characterized by XRD, FT-IR spectroscopy, FE-SEM, and VSM analysis. In addition, the stability of HEWLs exposed to different NP concentrations in the range of 0.001–0.1 mg mL⁻¹ was investigated by circular dichroism (CD) spectroscopy, fluorescence, and UV-Vis analysis. Based on the results, in the NP concentration range of 0.001–0.04 mg mL⁻¹ the protein structure is more stable, and this range was identified as the range of kosmotropic concentration. The helicity was measured at two concentration points of 0.02 and 0.1 mg mL⁻¹. According to the results, the α-helix at 0.02 mg mL⁻¹ of Fe₃O₄ and Fe₃O₄@Tre was increased from 35.5% for native protein to 37.7% and 38.7%, respectively. The helicity decreased to 36.1% and 37.4%, respectively, with increasing the concentration of Fe₃O₄ and Fe₃O₄@Tre to 0.1 mg mL⁻¹. The formation of hydrated water shells around protein molecules occurred by using Fe₃O₄@Tre NPs. Hence, it can be concluded that the trehalose as a functional group along with magnetic NPs can improve the stability of proteins in biological environments.

Anti-amyloidogenic property of gold nanoparticle decorated quercetin polymer nanorods in pH and temperature induced aggregation of lysozyme

Quercetin is an abundant plant polyphenol effective against several diseases due to its antioxidant and anti-inflammatory activity. Herein, we report novel polymeric quercetin nanorods and the former decorated with gold nanoparticles for the first time. The prepared conjugates quercetin-polyvinylpyrrolidone (Q-PVP) and quercetin-polyvinylpyrrolidone-gold nanoparticles (Q-PVP-Au) were characterized by UV-visible spectroscopy, Fourier transform infrared, dynamic light scattering, and zeta potential measurements. The surface morphology of conjugates was analyzed by field emission scanning electron microscopy. These conjugates exhibit harmonized rod-like morphology with a narrow size distribution. Furthermore, the quercetin conjugates with nanorod morphology exhibited enhanced and prolonged drug release over a long period. The synthesized conjugates were investigated for lysozyme aggregation kinetics. ThT binding assay, fibril size measurement, and electron microscopy results revealed that conjugates could suppress fibrillogenesis in lysozyme. The highest amyloid aggregation inhibition activity (IC50) was obtained against Q-PVP and Q-PVP-Au at 32 μg mL-1 and 30 μg mL-1 respectively. The amyloid aggregate disintegration activity (DC50) obtained against Q-PVP and Q-PVP-Au was 27 μg mL-1 and 29 μg mL-1 respectively. The present quercetin conjugates exhibit enhanced bioavailability and stability. They were potent inhibitors of lysozyme aggregation that may find applications as a therapeutic agent in neurological diseases like Alzheimer's and Parkinson's.

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.

Lysozyme amyloid fibril: Regulation, application, hazard analysis, and future perspectives

Self-assembly of misfolded proteins into ordered fibrillar aggregates known as amyloid results in various human diseases. However, more and more proteins, whether in human body or in food, have been found to be able to form amyloid fibrils with in-depth researches. As a model protein for amyloid research, lysozyme has always been the focus of research in various fields. Firstly, the formation mechanisms of amyloid fibrils are discussed concisely. Researches on the regulation of lysozyme amyloid fibrils are helpful to find suitable therapeutic drugs and unfriendly substances. And this review article summarizes a number of exogenous substances including small molecules, nanoparticles, macromolecules, and polymers. Small molecules are mainly connected to lysozyme through hydrophobic interaction, electrostatic interaction, π-π interaction, van der Waals force and hydrogen bond. Nanoparticles inhibit the formation of amyloid fibers by stabilizing lysozyme and fixing β-sheet. Besides, the applications of lysozyme amyloid fibrils in food-related fields are considered furtherly due to outstanding physical and mechanical properties. Nevertheless, the potential health threats are still worthy of our attention. Finally, we also give suggestions and opinions on the future research direction of lysozyme amyloid fibrils.

Inhibiting protein aggregation with nanomaterials: The underlying mechanisms and impact factors

Protein aggregation is correlated with the onset and progression of protein misfolding diseases (PMDs). Inhibiting the generation of toxic aggregates of misfolded proteins has been proposed as a therapeutic approach for PMDs. Due to their unique properties, nanomaterials have been extensively investigated for their ability to inhibit protein aggregation and have shown great potential in the diagnosis and treatment of PMDs. However, the precise mechanisms by which nanomaterials interact with amyloidogenic proteins and the factors influencing these interactions remain poorly understood. Consequently, developing a rational design strategy for nanomaterials that target specific proteins in PMDs has been challenging. In this review, we elucidate the effects of nanomaterials on protein aggregation and describe the mechanisms through which nanomaterials interfere with protein aggregation. The major factors impacting protein-nanomaterial interaction such as size, charge, concentration, surface modification and morphology that can be rationally addressed to achieve the desired effects of nanomaterials on protein aggregation are summarized. The prospects and challenges to the clinical application of nanomaterials for the treatment of PMDs are also discussed.

Supramolecular organization of Cytochrome-C into quantum-dot decorated macromolecular network under pH and thermal stress

The holo form of Cytochrome-C which is involved in the electron transfer chain of aerobic and anaerobic respiration remains structurally intact by its complex with heme. However, when a prolonged thermal and pH stress was applied, heme was found to abruptly dissociate from the holo protein, resulting in complete collapse of the three-dimensional functional structure. Interestingly, two distinct structures were formed as the consequence of the dissociation event: (i) A macromolecular amyloid-network formed by the collapsed protein fragments, generated by self-oxidation, and (ii) Fe-containing Quantum-Dots (FeQDs) with 2-3 nm diameter formed by heme reorganization. Further adding to intrigue, the FeQDs were re-adsorbed on the surface of the amyloid network leading to FeQD-decorated macromolecular amyloid matrix. The heme-interactant Met80, constituting the amyloidogenic region, initiates the amylogenic cascade, and gradual exposure of Trp59 synergistically emit intrinsic fluorescence alongside FeQDs. The development of the aforementioned events were probed through a multitude of biophysical, chemical and computational analyses like ThT/ANS/intrinsic fluorescence assays, CD-spectroscopy, FETEM/STEM/elemental mapping, Foldamyloid/Foldunfold/Isunstruct/H-protection/LIGplot analyses, etc. The FeQD-decorated amyloid-network was found to exhibit gel-like property, which supported the growth of BHK-21 fibroblast without cytotoxicity. Further studies on FeQD-decorated Cytochrome C amyloid network might open possibilities to design advanced biomaterial for diverse biological applications.

Potential Role of Nanoparticles in Treating the Accumulation of Amyloid-Beta Peptide in Alzheimer's Patients

The disorder of Alzheimer's is marked by progressive pathophysiological neurodegeneration. The amino acid peptides in the amyloid plaques found in the brains of people with Alzheimer's disease (AD) are known as amyloid-beta (Aβ). Current treatments are not curative, and the effects associated with AD are reduced. Improving treatment results involved the targeting of drugs at optimum therapeutic concentration. Nanotechnology is seen as an unconventional, modern technology that plays a key role in the treatment of Alzheimer's disease. Using nanoparticles, molecular detection, effective drug targeting, and their combination offer high sensitivity. The aim of this review is to shed light on the function and successful role of nanoparticles to resolve Aβ aggregation and thus to help cure Alzheimer's disease. The analysis divides these nanoparticles into three categories: polymer, lipid, and gold nanoparticles. A thorough comparison was then made between the nanoparticles, which are used according to their role, properties, and size in the procedure. The nanoparticles can prevent the accumulation of Aβ during the efficient delivery of the drug to the cells to treat Alzheimer's disease. Furthermore, this comparison demonstrated the ability of these nanoparticles to deal efficiently with Alzheimer's disease. The role of these nanoparticles varied from delivering the drug to brain cells to dealing with the disease-causing peptide.

The distinct binding modes of pesticides affect the phase transitions of lysozyme

Studying the aggregation and nucleation of proteins in the presence of organic molecules is helpful for disclosing the mechanisms of protein crystallization.

Synthesis of linear polyglucoside and inhibition on the amyloid fibril formation of hen egg white lysozyme

A novel polymer poly (6-O-MMAGlc) has been synthesized via free radical polymerization of monomer methyl 6-O-methacryloyl-α-D-glucoside (6-O-MMAGlc) and characterized. The influence of poly(6-O-MMAGlc) on the formation of hen egg white lysozyme (HEWL) amyloid fibril was detailly investigated, indicating that the polymer could effectively inhibit the formation of HEWL amyloid fibril. The formation kinetics of HEWL amyloid fibril with the presence of poly(6-O-MMAGlc) was measured by Thioflavin T (ThT) fluorescence method, demonstrating that poly(6-O-MMAGlc) could significantly inhibit the amyloid fibril formation of HEWL in a dose-dependent manner. The inhibitory result was furtherly illustrated by congo red (CR) binding assay, 8-anilino-1-naphthalenesulfonic acid (ANS) fluorescence assay, circular dichroism (CD) spectroscopy and transmission electron microscope (TEM).

Optical characterization and tunable antibacterial properties of gold nanoparticles with common proteins

The interaction of three proteins, viz. Bovine Serum Albumin (BSA), Human Serum Albumin (HSA) and Hen Egg White Lysozyme (HEWL) with gold nanoparticles (GNPs) is investigated using surface plasmon resonance (SPR) spectroscopy, fluorescence spectroscopy and circular dichroism (CD). Size and morphology of the samples was established using Transmission Electron Microscopy (TEM) and stability studies was established using zeta potential analysis. The stability of protein-GNP complex was found to be greater than that of individual protein as well as individual GNPs. Also HEWL-GNP complex was more stable compared to the other protein complexes. Absorbance of proteins increases with increase in gold nanoparticle concentration due to the extension of peptide strands of protein and decrease in hydrophobicity of gold nanoparticles. A ground state complex is also formed which is evident from the moderate shift observed in the absorbance peaks. Apparent association constant was also determined from the absorption spectra and was found to be maximum for HEWL and minimum for HSA. Gold nanoparticles were found to act as quenchers and reduced the protein fluorescence intensity. Binding constant and number of binding sites were found to be maximum for HEWL and minimum for HSA. The temperature dependent fluorescence studies were also performed to calculate the thermodynamic parameters and to determine the nature of interaction between the proteins and gold nanoparticles. The circular dichroism studies elucidate the reason behind the maximum binding for HEWL and minimum binding for HSA. TGA analysis determined the thermal stability of the samples. Fluorescence lifetime studies indicate static quenching of proteins. Antibacterial activity of protein-gold nanoparticles was studied against four pathogens, viz. Bacillus pumilus, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. HEWL exhibits a tunable antimicrobial activity against Pseudomonas aeruginosa due to the maximum binding of HEWL with gold nanoparticles. The study proposes a novel method for adjusting the antibacterial activity of HEWL against Pseudomonas aeruginosa when the resistance of this pathogen is a major issue in the chemotherapy of many infectious diseases. Thus the combination therapy of protein-gold nanoparticles could prove to be a new approach in medical field in the near future.

Effect of curcumin derivatives on hen egg white lysozyme amyloid fibrillation and their interaction study by spectroscopic methods

Two novel Boc-L-isoleucine-functionalized curcumin derivatives have been synthesized and characterized, which exhibited enhanced solubility in water compared with the natural curcumin. The solubility could reach 2.12mg/mL for the monosubstituted compound and 3.05mg/mL for the disubstituted compound, respectively. Their anti-amyloidogenic capacity on the model protein, hen egg white lysozyme (HEWL), was examined in aqueous solution. ThT fluorescence assay showed that the operation concentration was only 0.5mM when the inhibition ratio was above 70%. Meanwhile, the inhibitory capacity of monosubstituted curcumin derivative on the formation of HEWL amyloid fibrils was found to be superior to that of disubstituted derivative, suggesting that the phenolic hydroxyl group might contribute to the anti-amyloidogenic activity. Interaction study showed that both curcumin derivatives could bind with HEWL near tryptophan residues and form new ground-state complex before HEWL self-assemblies into amyloid fibrils and thus inhibits the formation of amyloid fibrils. Both of the two cucumin derivatives have displayed low cytotoxicity with HeLa cell.