The effect of green synthesis silver nanoparticles (AgNPs) from Pulicaria undulata on the amyloid formation in α-lactalbumin and the chaperon action of α-casein

Tailoring ternary complexes of lactoferrin, EGCG, and α-lactalbumin by assembly sequence strategies: Structural characterization, assembly mechanism, and emulsification elucidation

Three distinct ternary complexes (TC-M1, TC-M2, and TC-M3) based on lactoferrin (LF), (-)-epigallocatechin-3-gallate (EGCG), and α-lactalbumin (ALA) were prepared by varying the assembly sequence and EGCG concentrations (ranging from 0 to 2.0 mM). Structural characterization was performed using various spectroscopic techniques, while the assembly mechanisms were investigated through ITC and molecular docking. These ternary complexes were further evaluated as stabilizers in Pickering emulsions. Nephelometry and DLS analysis showed that TC-M1 exhibited the highest turbidity and largest particle size, followed by TC-M2 and TC-M3. FT-IR and fluorescence spectroscopy revealed strong binding between EGCG and both ALA and LF, enhancing the hydrophilicity and extending structure of proteins. ITC and molecular docking studies indicated spontaneous interactions primarily driven by hydrogen bonding and hydrophobic forces, with LF (Ka1 = 1.9 × 105 M-1) and ALA (Ka1 = 3.6 × 104 M-1) binding approximately 3.3 and 2.9 EGCG molecules, respectively. Pickering emulsions formed by these complexes demonstrated superior emulsification properties, with TC-M1 showing the smallest CI (10.09 % ± 0.19 %), particle size (1 to 2 μm), and higher MVI (1.2) and EI (2.5) at 2.0 mM EGCG, outperforming TC-M2 and TC-M3 in stability. Overall, the assembly sequence of LF, ALA, and EGCG, along with EGCG concentration, lays the foundation for designing protein-polyphenol-protein ternary complexes, offering enhanced stability and functionality for diverse EGCG delivery applications.

Unveiling the Correlation between Protein, Protein Corona, and Target Signal Loss in SERS Detection

The application of surface-enhanced Raman scattering (SERS) technology is hindered by the protein corona in a protein-rich complex matrix, which is a hot and important issue that needs consideration. However, the impact of the protein corona on SERS detection has not been fully studied. Herein, we selected three proteins, α-lactalbumin (α-La), β-lactoglobulin (β-Lg), and bovine serum albumin (BSA), as models for forming a protein corona, and melamine was employed as the target in SERS detection. The results indicate that three proteins form a protein corona on gold nanoparticles (AuNPs), leading to a significant loss of melamine signals. With increasing protein concentration, the degree of loss increases. The protein corona significantly inhibits target-induced nanoparticle aggregation, increases the distance between neighboring nanoparticles, and reduces the formation of "hot-spot" regions. Moreover, the adsorption capacity of AuNPs for melamine decreases, reducing the number of molecules that can achieve direct chemical enhancement. The Raman signal loss caused by different types of proteins, varies, even at the same molecule number, which is related to the deformability of proteins. This deformability determines the density of the protein corona formed on the surface of the AuNPs. Our results advance the fundamental understanding of the relationship between proteins, protein corona, and target signal loss in SERS detection, offering valuable insights for establishing models to predict Raman signal loss in protein-rich samples.

Probing the effect of protein corona on SERS signals: insights from melamine detection in milk matrix

Matrix effects limit the application of surface-enhanced Raman scattering (SERS) technology in the field of food safety. This study elucidated it from the perspective of protein corona by employing a model system for melamine SERS detection in milk. Compared with the melamine standard solution, higher detection limits (1 mg/L and 10 mg/L) are observed in milk matrix. The melamine signal exhibits an 80% reduction in whey protein solution, suggesting that protein has a significant impact on SERS signals. The changes in particle size, zeta potential and UV-vis spectra indicate the AuNPs interact with whey protein. Forming protein corona inhibits the melamine-induced AuNPs aggregation, reducing the number of 'hot spot' and the adsorption of melamine on AuNPs (from 0.28 mg/L to 0.07 mg/L), which may be responsible for signal loss. The found matrix effect from protein corona provides new insights for developing strategies about reducing matrix effect in SERS application.

Thespesia lampas mediated green synthesis of silver and gold nanoparticles for enhanced biological applications

The present study investigated the synthesis and biological applications of green, economical, and multifunctional silver and gold nanoparticles (TSAgNPs and TSAuNPs) using the ethnomedical important medicinal plant Thespesia lampas for biological activities. Relatively higher levels of antioxidant components were measured in T. lampas compared to the well-known Adhatoda vasica, and Diplocyclos palmatus suggested the potential of T. lampas for the study. Synthesized TSAgNPs and TSAuNPs were characterized through UV-Vis, XRD, SEM-EDS, HR-TEM, SAED, and FTIR techniques. SEM revealed that TSAgNPs and TSAuNPs were predominantly spherical in shape with 19 ± 7.3 and 43 ± 6.3 nm crystal sizes. The sizes of TSAgNPs and TSAuNPs were found to be12 ± 4.8 and 45 ± 2.9 nm, respectively, according to TEM measurements. The FTIR and phytochemical analyses revealed that the polyphenols and proteins present in T. lampas may act as bio-reducing and stabilizing agents for the synthesis. Synthesized NPs exhibited enhanced scavenging properties for ABTS and DPPH radicals. TSAgNPs and TSAuNPs were able to protect DNA nicking up to 13.48% and 15.38%, respectively, from oxidative stress. TSAgNPs possessed efficient antibacterial activities in a concentration-dependent manner against human pathogenic bacteria, such as E. coli, B. subtilis, P. vulgaris, and S. typhi. Furthermore, TSAgNPs and TSAuNPs showed significant cytotoxicity against FaDu HNSCC grown in 2D at 50 and 100 μg mL-1. Tumor inhibitory effects on FaDu-derived spheroid were significant for TSAgNPs > TSAuNPs at 100 μg mL-1 in 3D conditions. Dead cells were highest largely for TSAgNPs (76.65% ± 1.76%), while TSAuNPs were non-significant, and Saq was ineffectively compared with the control. However, the diameter of the spheroid drastically reduced for TSAgNPs (3.94 folds) followed by TSAuNPs (2.58 folds), Saq (1.94 folds), and cisplatin (1.83 folds) at 100 μg mL-1. The findings of the study suggested the bio-competence of TSAgNPs and TSAuNPs as multi-responsive agents for antioxidants, DNA protection, antibacterial, and anti-tumor activities to provide a better comprehension of the role of phytogenic nanoparticles in healthcare systems.

Myricetin and morin hydrate inhibit amyloid fibril formation of bovine α-lactalbumin (BLA)

Amyloid fibrils are self-assembled aggregates of proteins and peptides that can lead to a broad range of diseases called amyloidosis. So far, no definitive and approved treatment to target directly amyloid fibrils has been introduced. Nevertheless, the search for small molecules with ability to inhibit and suppress fibril formation is an active and promising area of the research. Herein, the binding interactions and inhibitory effects of myricetin and morin hydrate on the in vitro fibrillation of bovine α-lactalbumin (BLA) have been investigated. The intrinsic fluorescence of BLA was quenched by myricetin and morin hydrate through combination of the static and dynamic quenching along with non-radiative Förster energy transfer mechanisms. The binding of these two flavonoids to BLA were not accompanied by major alteration in the conformation of BLA as evidenced by CD studies. The results of the fluorescence quenching analyses indicated almost the same binding affinities of myricetin and morin hydrate toward BLA (Kb ~ 106 M-1). However, the results of thioflavin T (ThT) assays showed that myricetin is a stronger inhibitor against BLA fibrillation compared to morin hydrate.

Self-Therapeutic Nanomaterials: Applications in Biology and Medicine

Over past decades, nanotechnology has contributed to the biomedical field in areas including detection, diagnosis, and drug delivery via opto-electronic properties or enhancement of biological effects. Though generally considered inert delivery vehicles, a plethora of past and present evidence demonstrates that nanomaterials also exude unique intrinsic biological activity based on composition, shape, and surface functionalization. These intrinsic biological activities, termed self-therapeutic properties, take several forms, including mediation of cell-cell interactions, modulation of interactions between biomolecules, catalytic amplification of biochemical reactions, and alteration of biological signal transduction events. Moreover, study of biomolecule-nanomaterial interactions offers a promising avenue for uncovering the molecular mechanisms of biology and the evolution of disease. In this review, we observe the historical development, synthesis, and characterization of self-therapeutic nanomaterials. Next, we discuss nanomaterial interactions with biological systems, starting with administration and concluding with elimination. Finally, we apply this materials perspective to advances in intrinsic nanotherapies across the biomedical field, from cancer therapy to treatment of microbial infections and tissue regeneration. We conclude with a description of self-therapeutic nanomaterials in clinical trials and share our perspective on the direction of the field in upcoming years.

Nanodelivery of antiretroviral drugs to nervous tissues

Despite the development of effective combined antiretroviral therapy (cART), the neurocognitive impairments associated with human immunodeficiency virus (HIV) remain challenging. The presence of the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCFB) impedes the adequate penetration of certain antiretroviral drugs into the brain. In addition, reports have shown that some antiretroviral drugs cause neurotoxicity resulting from their interaction with nervous tissues due to long-term systemic exposure. Therefore, the research into the effective therapeutic modality that would cater for the HIV-associated neurocognitive disorders (HAND) and ART toxicity is now receiving broad research attention. Thus, this review explores the latest information in managing HAND using a nanoparticle drug delivery system (NDDS). We discussed the neurotoxicity profile of various approved ART. Also, we explained the applications of silver nanoparticles (AgNPs) in medicine, their different synthesis methods and their interaction with nervous tissues. Lastly, while proposing AgNPs as useful nanoparticles in properly delivering ART to enhance effectiveness and minimize neurocognitive disorders, we hypothesize that the perceived toxicity of AgNPs could be minimized by taking appropriate precautions. One such precaution is using appropriate reducing and stabilizing agents such as trisodium citrate to reduce silver ion Ag + to ground state Ag0 during the synthesis. Also, the usage of medium-sized, spherical-shaped AgNPs is encouraged in AgNPs-based drug delivery to the brain due to their ability to deliver therapeutic agents across BBB. In addition, characterization and functionalization of the synthesized AgNPs are required during the drug delivery approach. Putting all these factors in place would minimize toxicity and enhance the usage of AgNPs in delivering therapeutic agents across the BBB to the targeted brain tissue and could cater for the HIV-associated neurocognitive disorders and neurotoxic effects of antiretroviral drugs (ARDs).

Inorganic Nanomaterials versus Polymer-Based Nanoparticles for Overcoming Neurodegeneration

Neurodegenerative disorders (NDs) affect a great number of people worldwide and also have a significant socio-economic impact on the aging population. In this context, nanomedicine applied to neurological disorders provides several biotechnological strategies and nanoformulations that improve life expectancy and the quality of life of patients affected by brain disorders. However, available treatments are limited by the presence of the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (B-CSFB). In this regard, nanotechnological approaches could overcome these obstacles by updating various aspects (e.g., enhanced drug-delivery efficiency and bioavailability, BBB permeation and targeting the brain parenchyma, minimizing side effects). The aim of this review is to carefully explore the key elements of different neurological disorders and summarize the available nanomaterials applied for neurodegeneration therapy looking at several types of nanocarriers. Moreover, nutraceutical-loaded nanoparticles (NPs) and synthesized NPs using green approaches are also discussed underling the need to adopt eco-friendly procedures with a low environmental impact. The proven antioxidant properties related to several natural products provide an interesting starting point for developing efficient and green nanotools useful for neuroprotection.

Applications of Phyto-Nanotechnology for the Treatment of Neurodegenerative Disorders

The strategies involved in the development of therapeutics for neurodegenerative disorders are very complex and challenging due to the existence of the blood-brain barrier (BBB), a closely spaced network of blood vessels and endothelial cells that functions to prevent the entry of unwanted substances in the brain. The emergence and advancement of nanotechnology shows favourable prospects to overcome this phenomenon. Engineered nanoparticles conjugated with drug moieties and imaging agents that have dimensions between 1 and 100 nm could potentially be used to ensure enhanced efficacy, cellular uptake, specific transport, and delivery of specific molecules to the brain, owing to their modified physico-chemical features. The conjugates of nanoparticles and medicinal plants, or their components known as nano phytomedicine, have been gaining significance lately in the development of novel neuro-therapeutics owing to their natural abundance, promising targeted delivery to the brain, and lesser potential to show adverse effects. In the present review, the promising application, and recent trends of combined nanotechnology and phytomedicine for the treatment of neurological disorders (ND) as compared to conventional therapies, have been addressed. Nanotechnology-based efforts performed in bioinformatics for early diagnosis as well as futuristic precision medicine in ND have also been discussed in the context of computational approach.

Natural Product-based Nanomedicine: Recent Advances and Issues for the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) affects the elderly and is characterized by progressive neurodegeneration caused by different pathologies. The most significant challenges in treating AD include the inability of medications to reach the brain because of its poor solubility, low bioavailability, and the presence of the blood-brain barrier (BBB). Additionally, current evidence suggests the disruption of BBB plays an important role in the pathogenesis of AD. One of the critical challenges in treating AD is the ineffective treatments and their severe adverse effects. Nanotechnology offers an alternative approach to facilitate the treatment of AD by overcoming the challenges in drug transport across the BBB. Various nanoparticles (NP) loaded with natural products were reported to aid in drug delivery for the treatment of AD. The nano-sized entities of NP are great platforms for incorporating active materials from natural products into formulations that can be delivered effectively to the intended action site without compromising the material's bioactivity. The review highlights the applications of medicinal plants, their derived components, and various nanomedicinebased approaches for the treatment of AD. The combination of medicinal plants and nanotechnology may lead to new theragnostic solutions for the treatment of AD in the future.

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.

α-Lactalbumin, Amazing Calcium-Binding Protein

α-Lactalbumin (α-LA) is a small (Mr 14,200), acidic (pI 4–5), Ca²⁺-binding protein. α-LA is a regulatory component of lactose synthase enzyme system functioning in the lactating mammary gland. The protein possesses a single strong Ca²⁺-binding site, which can also bind Mg²⁺, Mn²⁺, Na⁺, K⁺, and some other metal cations. It contains several distinct Zn²⁺-binding sites. Physical properties of α-LA strongly depend on the occupation of its metal binding sites by metal ions. In the absence of bound metal ions, α-LA is in the molten globule-like state. The binding of metal ions, and especially of Ca²⁺, increases stability of α-LA against the action of heat, various denaturing agents and proteases, while the binding of Zn²⁺ to the Ca²⁺-loaded protein decreases its stability and causes its aggregation. At pH 2, the protein is in the classical molten globule state. α-LA can associate with membranes at neutral or slightly acidic pH at physiological temperatures. Depending on external conditions, α-LA can form amyloid fibrils, amorphous aggregates, nanoparticles, and nanotubes. Some of these aggregated states of α-LA can be used in practical applications such as drug delivery to tissues and organs. α-LA and some of its fragments possess bactericidal and antiviral activities. Complexes of partially unfolded α-LA with oleic acid are cytotoxic to various tumor and bacterial cells. α-LA in the cytotoxic complexes plays a role of a delivery carrier of cytotoxic fatty acid molecules into tumor and bacterial cells across the cell membrane. Perhaps in the future the complexes of α-LA with oleic acid will be used for development of new anti-cancer drugs.

Bleomycin modulates amyloid aggregation in β-amyloid and hIAPP

Aberrant misfolding and amyloid aggregation, which result in amyloid fibrils, are frequent and critical pathological incidents in various neurodegenerative disorders. Multiple drugs or inhibitors have been investigated to avert amyloid aggregation in individual peptides, exhibiting sequence-dependent inhibition mechanisms. Establishing or inventing inhibitors capable of preventing amyloid aggregation in a wide variety of amyloid peptides is quite a daunting task. Bleomycin (BLM), a complex glycopeptide, has been widely used as an antibiotic and antitumor drug due to its ability to inhibit DNA metabolism, and as an antineoplastic, especially for solid tumors. In this study, we investigated the dual inhibitory effects of BLM on Aβ aggregation, associated with Alzheimer's disease and hIAPP, which is linked to type 2 diabetes, using both computational and experimental techniques. Combined results from drug repurposing and replica exchange molecular dynamics simulations demonstrate that BLM binds to the β-sheet region considered a hotspot for amyloid fibrils of Aβ and hIAPP. BLM was also found to be involved in β-sheet destabilization and, ultimately, in its reduction. Further, experimental validation through in vitro amyloid aggregation assays was obtained wherein the fibrillar load was decreased for the BLM-treated Aβ and hIAPP peptides in comparison to controls. For the first time, this study shows that BLM is a dual inhibitor of Aβ and hIAPP amyloid aggregation. In the future, the conformational optimization and processing of BLM may help develop various efficient sequence-dependent inhibitors against amyloid aggregation in various amyloid peptides.

Bleomycin acts as a dual inhibitor against both amyloid β and human islet amyloid polypeptide by binding to the β-sheet grooves considered as the amyloids hotspot.

Devil's hand conceals behind the obscure side of AgNPs: A letter to the editor

From that time AgNPs become one of the most accessible and important antibacterial agents in our world, thousands of papers published regarding investigating all aspects of these materials. When the time elapsed and novel methods contrived to follow the fingerprint of AgNPs in the in vivo models, some critical concerns and arguments also appeared between researchers about the safety of these compounds for living cells and vital organs. The paper by Dehvari and Ghahaghaei published in Volume 108 International Journal of Biological Macromolecules, pages 1128-1139 (Dehvari and Ghahghaei, 2018) suffered some errors from safety concerns to obscurities in the results essentially needing the amendment to enhance its quality. Though the author(s) idea is commended enough, nevertheless, I could not find a profound trace with their results, and my concerns are discussed in detail as the following lines.

Letter to the Editor

I read with great interest the paper by Dehvari and Ghahghaei (Dehvari and Ghahghaei, 2018 [1]). Their paper aimed to prove that biosynthesized AgNPs mediated by Pulicaria undulata L. has the capability in inhibiting amyloid fibril formation and thus could be considered as a therapeutic agent in the treatment of amyloidosis disorders. According to the literature (Jangholi et al., 2018 [2]), Thioflavin T (ThT) is a commonly used probe to monitor in vitro amyloid fibril formation. Also, since ThT fluorescence originates only from the bound population of the dye molecules, the several orders of magnitude increase in the fluorescence intensity makes ThT an unusually sensitive and efficient reporter. The authors used ThT to monitor in vitro amyloid fibril formation of α-lactalbumin and fluorescence emission spectra were recorded upon titration of the indicated concentrations of nanoparticles or α-casein. They excited the assay solutions at 450nm and the emissions were measured over the range 460-600nm. Interestingly, upon binding to α-lactalbumin's amyloid fibrils, ThT displayed a (slight) relative increase of fluorescence signal at approximately ~530-540nm, when excited at 450nm with no background ThT fluorescence subtraction/reportage. Upon binding to amyloid fibrils, ThT generally exhibits a dramatic shift of the excitation maximum (from 385nm to 450nm) and the emission maximum from 445nm to the higher wavelengths, along with a strong fluorescence signal at ~482nm (Biancalana, 1804 [3]). Regarding the wavelength of ThT fluorescence maxima, the obtained results by Dehvari and Ghahghaei are inconsistent with what has yet been reported in the literature. Moreover, the respected authors, in the present work, have not tried to describe these unusual ThT results. However, I could not find evidence/fingerprint of "cotton effect" of ThT and/or absorption flattening within the results.