Inhibition of amyloid fibrillation, enzymatic degradation and cytotoxicity of insulin at carboxyl tailored gold-aryl nanoparticles surface

Enhanced delivery of doxorubicin via transferrin-coated arylated gold nanostars for cancer therapy

Transferrin protein-coated gold-aryl nanoparticles (TRF-AuNPs) and nanostars (TRF-AuNSs) were synthesized and characterized. The water-dispersible gold-aryl nanoparticles and nanostars covalently functionalized with a -C6H4-4-COOH organic shell were synthesized from an aryldiazonium gold(III) salt. TRF-AuNPs had an average size of 10.5 ± 5.6 nm, and TRF-AuNSs had an average size of 177.4 ± 31.3 nm, as obtained with transmission electron microscopy. The zeta potential values indicated a positive surface charge of + 35 mV for both bioconjugates, indicating successful functionalization. An MTT assay was performed to investigate the cytotoxicity of TRF-AuNSs, which was confirmed to be non-toxic in the MDA-MB-231 breast cancer cell line. Cellular uptake was analyzed using flow cytometry and confocal microscopy. TRF was chosen to functionalize gold-aryl NPs and gold-aryl NSs because of the overexpression of its receptors on cancer cells. The efficiency of TRF-AuNSs was investigated, and the TRF protein receptor expression on cancer cells was probed using polymerase chain reaction (PCR). The antiproliferative effects of the doxorubicin drug (Dox) were assessed; the gold nanomaterials were evaluated as efficient carriers for the anticancer drug Dox. Dox-coated TRF-gold nanomaterials induced apoptosis and necrosis via DNA damage and increased ROS levels, as confirmed by flow cytometry and spectrofluorometry. Our study supports the significance of the shape of gold nanomaterials in Dox drug delivery to cancer cells.

Bacterial synthesis of anisotropic gold nanoparticles

Pseudomonas aeruginosa was used to synthesize anisotropic gold nanoparticles from the unusually reducible aryldiazonium gold (III) salt of the chemical formula [HOOC-4-C6H4N≡N]AuCl4 (abbreviated as DS-AuCl4). We investigated the effect of bacterial cell density, temperature, and pH on the AuNP synthesis. The bacterial cell density of 6.0 × 108 CFU/mL successfully reduced 0.5 mM DS-AuCl4 salt to AuNPs after incubation at 37 °C (24 h), 42 °C (24 h), and 25 °C (48 h). Transmission electron microscopy (TEM) images revealed the formation of spherical, triangle, star, hexagon, and truncated triangular morphologies for the AuNPs synthesized using P. aeruginosa bacteria. The average size of AuNPs synthesized at 25 °C (48 h), 37 °C (24 h), and 42 °C (24 h) was 39.0 ± 9.1 nm, 26.0 ± 8.1 nm, and 36.7 ± 7.7 nm, respectively. The average size of AuNPs synthesized at pH 3.7, 7.0, and 12.7 was 36.7 ± 7.7 nm, 14.7 ± 3.8 nm, and 7.3 ± 2.5 nm, respectively, with the average size decreasing at a pH of 12.7. The reduction of the DS-AuCl4 salt was confirmed using X-ray photoelectron spectroscopy (XPS). The significant peaks for C1s, Au4f doublet, N1s, and O1s are centered at 285, 84-88, 400, and 532 eV. The ability of inactivated bacteria (autoclave-dead and mechanically lysed bacteria), peptidoglycan, and lipopolysaccharides to reduce the DS-AuCl4 salt to AuNPs was also investigated. Anisotropic AuNPs were synthesized using inactivated bacteria and peptidoglycan but not using lipopolysaccharides. The AuNPs demonstrated biocompatibility with human RBCs and were safe, with no antibacterial activities against Escherichia coli and Staphylococcus aureus. This is the first report demonstrating the synthesis of AuNPs using aryldiazonium gold(III) salts with P. aeruginosa. These AuNPs are promising candidates for exploring potential applications in nanomedicine and drug delivery. KEY POINTS: • Anisotropic AuNPs were synthesized using P. aeruginosa bacteria. • Dead and lysed bacterial residues synthesized anisotropic AuNPs. • AuNPs are hemocompatible.

Advances in Alzheimer's disease control approaches via carbon nanotubes

Global concern about Alzheimer's disease (AD) is justified by its increasingly younger onset and significant economic burden. AD leads to neurodegeneration and cognitive decline, ultimately resulting in loss of autonomy. Against this background, the field of biomedical research has seen a surge of interest in the potential of carbon-based nanomaterials, mainly due to their ease of degradation and high biocompatibility. Carbon nanotubes (CNTs) have been extensively studied in AD, including developing biosensors, drug delivery systems, and molecular imaging. Here, we introduced the biosafety and biodegradability of CNTs, with a particular focus on their uptake and degradation in brain tissue. The utilization of CNT in the context of AD therapy can facilitate the advancement of control approaches regimens and ensure the clinical safety of patients. This is achieved through the employment of these nanotubes as carriers for the delivery of drugs to the central nervous system (CNS), the detection of neurotransmitters such as acetylcholine (Ach) and monoamines, the development of biosensors and molecular imaging materials, the inhibition of Aβ formation and the detection of phosphorylated tau proteins, the promotion of CNS regeneration, and the modulation of ion-associated AD.

Development of nanomedicines for the treatment of Alzheimer's disease: Raison d'être, strategies, challenges and regulatory aspects

Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by progressive loss of memory. Presently, AD is challenging to treat with current drug therapy as their delivery to the brain is restricted by the presence of the blood-brain barrier. Nanomedicines, due to their size, high surface volume ratio, and ease of tailoring drug release characteristics, showed their potential to treat AD. The nanotechnology-based formulations for brain targeting are expected to enter the market in the near future. So, regulatory frameworks are required to ensure the quality, safety, and effectiveness of the nanomedicines to treat AD. In this review, we discuss different strategies, in-vitro blood-brain permeation models, in-vivo permeation assessment, and regulatory aspects for the development of nanomedicine to treat AD.

Carbon nanomaterials: A growing tool for the diagnosis and treatment of diabetes mellitus

Diabetes mellitus is a growing disease that affects people of different ages due to deficiencies in insulin action and secretion. Diabetes causing long-term hyperglycemia damages, destroys, and fails essential organs, including kidneys, eyes, hearts, nerves, and blood vessels. The involvement of pathogenic factors makes diabetes mellitus a severe disease. The autoimmune process results in insulin deficiency by destroying the beta-cells in the pancreas. This leads to insulin resistance. As a result of defects and abnormalities in fat, carbohydrate, and protein synthesis, insulin does not work as it should on the target tissues. As diabetes mellitus becomes, more severe, long-term and effective treatment becomes necessary. A wide range of nanomaterials can be used to treat diabetes mellitus in patients. In addition to being potential imaging, diagnostic, and treatment agents for diabetes mellitus, carbon nanomaterials (CNMs) are another group of nanoparticles that exhibit potential interest. The CNMs acts as implantable nanosensor to track and detect blood glucose level in patients with diabetes. CNMS are possible drug carriers that can treat diabetes mellitus selectively, precisely, and effectively. Diabetes mellitus can be diagnosed and treated with CNMs due to their structural specificity and high drug-loading efficiency. The present review explores CNMs for their types, synthesis, and anti-diabetic properties. This review aims to provide a detailed view of the new technology that can be used to decipher the mechanism of CNMs in diabetes mellitus.

Effect of mono- and diketone group in curcumin analogues on amyloid fibrillation of hen egg white lysozyme

Curcumin has attracted more attention because of its inhibition efficacy on protein amyloid fibrillation. However, the inhibition mechanism was still ambiguous and the clinical application of curcumin was greatly limited because of its poor stability at physiological conditions for the presence of β-diketone moiety. In this paper, a new mono-ketone-containing curcumin analogue (MDHC) was designed and synthesized to realize the possible inhibition mechanism and unveil the important role of β-diketone moiety of curcumin in the inhibition process of amyloid fibrillation using hen egg white lysozyme (HEWL) as model protein. Although all experiment results (ThT, CR, ANS and TEM) showed that the inhibitory capacity of curcumin was better than MDHC, MDHC still could show obvious inhibition effect. Molecular docking showed that both curcumin and MDHC could bind with HEWL by hydrogen bond of phenloic hydroxyl and the binding energy of MDHC was higher than that of curcumin. All the findings inferred that β-diketone group was one of great important groups in the inhibition process of HEWL amyloid fibrillation, which provided more room to construct novel inhibition reagents.

HSA nanoparticles in drug recognition: mechanistic insights with naproxen, diclofenac and methimazole

Protein-based nanoparticles offer a suitable targeted delivery platform to drugs in terms of biocompatibility, biodegradability and abundance in nature. Physicochemical understanding of drug encapsulation by protein nanoparticles and their impact on protein aggregation is essential. In this work, we have examined quantitative aspects of encapsulation of non-steroidal anti-inflammatory drugs naproxen and diclofenac sodium, and anti-thyroid drug methimazole in nanoparticles of human serum albumin (HSA NPs) by using ultrasensitive calorimetry. Thermodynamic signatures accompanying the interactions revealed that the partitioning of all these drugs in HSA NPs is primarily driven via contributions from desolvation of highly hydrated nanoparticles surface. Furthermore, the effect of these nanoparticles on fibrillation of HSA has also been studied. HSA NPs are determined to be ineffective towards inhibition of fibrillation under employed conditions. However, the extent of inhibition by HSA NPs varies depending upon the structural characteristics of the drugs. Such studies help to gain mechanistic aspects on drug loading into protein-based nanoparticles and are expected to provide useful insights into improving existing nano-drug carriers and their efficiency in preventing protein fibrillation.Communicated by Ramaswamy H. Sarma.

Conceptual Developments of Aryldiazonium Salts as Modifiers for Gold Colloids and Surfaces

Modified colloids and flat surfaces occupy an important place in materials science research due to their widespread applications. Interest in the development of modifiers that adhere strongly to surfaces relates to the need for stability under ambient conditions in many applications. Diazonium salts have evolved as the primary choice for the modification of surfaces. The term "diazonics" has been introduced in the literature to describe "the science and technology of aryldiazonium salt-derived materials". The facile reduction of diazonium salts via chemical or electrochemical processes, irradiation stimuli, or spontaneously results in the efficient modification of gold surfaces. Robust gold-aryl nanoparticles, where gold is connected to the aryl ring through bonding to carbon and films modified by using diazonium salts, are critical in electronics, sensors, medical implants, and materials for power sources. Experimental and theoretical studies suggest that gold-carbon interactions constructed via chemical reactions with diazonium salts are stronger than nondiazonium surface modifiers. This invited feature article summarizes the conceptual development of recent studies of diazonium salts in our laboratories and others with a focus on the surface modification of gold nanostructures, flat surfaces and gratings, and their applications in nanomedicine engineering, sensors, energy, forensic science, and catalysis.

The impact of chemical engineering and technological advances on managing diabetes: present and future concepts

Monitoring blood glucose levels for diabetic patients is critical to achieve tight glycaemic control. As none of the current antidiabetic treatments restore lost functional β-cell mass in diabetic patients, insulin injections and the use of insulin pumps are most widely used in the management of glycaemia. The use of advanced and intelligent chemical engineering, together with the incorporation of micro- and nanotechnological-based processes have lately revolutionized diabetic management. The start of this concept goes back to 1974 with the description of an electrode that repeatedly measures the level of blood glucose and triggers insulin release from an infusion pump to enter the blood stream from a small reservoir upon need. Next to the insulin pumps, other drug delivery routes, including nasal, transdermal and buccal, are currently investigated. These processes necessitate competences from chemists, engineers-alike and innovative views of pharmacologists and diabetologists. Engineered micro and nanostructures hold a unique potential when it comes to drug delivery applications required for the treatment of diabetic patients. As the technical aspects of chemistry, biology and informatics on medicine are expanding fast, time has come to step back and to evaluate the impact of technology-driven chemistry on diabetics and how the bridges from research laboratories to market products are established. In this review, the large variety of therapeutic approaches proposed in the last five years for diabetic patients are discussed in an applied context. A survey of the state of the art of closed-loop insulin delivery strategies in response to blood glucose level fluctuation is provided together with insights into the emerging key technologies for diagnosis and drug development. Chemical engineering strategies centered on preserving and regenerating functional pancreatic β-cell mass are evoked in addition as they represent a permanent solution for diabetic patients.

Nanomaterial synthesis, an enabler of amyloidosis inhibition against human diseases

Amyloid diseases are global epidemics with no cure currently available. In the past decade, the use of engineered nanomaterials as inhibitors or probes against the pathogenic aggregation of amyloid peptides and proteins has emerged as a new frontier in nanomedicine. In this Minireview, we summarize for the first time the pivotal role of chemical synthesis in enabling the development of this multidisciplinary field.

Diazonium Gold Salts as Novel Surface Modifiers: What Have We Learned So Far?

The challenges of diazonium salts stabilization have been overcome by their isolation as metal salts such as tetrachloroaurate(III). The cleavage of molecular nitrogen from diazonium salts even at very low potential or on reducing surfaces by fine tuning the substituents on the phenyl ring expanded their applications as surface modifiers in forensic science, nanomedicine engineering, catalysis and energy. The robustness of the metal–carbon bonding produced from diazonium salts reduction has already opened an era for further applications. The integration of experimental and calculations in this field catalyzed its speedy progress. This review provides a narrative of the progress in this chemistry with stress on our recent contribution, identifies potential applications, and highlights the needs in this emerging field. For these reasons, we hope that this review paper serves as motivation for others to enter this developing field of surface modification originating from diazonium salts.