Green synthesis of novel stable biogenic gold nanoparticles for breast cancer therapeutics via the induction of extrinsic and intrinsic pathways

Attenuation of biofilm and virulence factors of Pseudomonas aeruginosa by tetramethylpyrazine-gold nanoparticles

Pseudomonas aeruginosa is often identified as the causative agent in nosocomial infections. Their adapted resistance makes them strong towards antimicrobial treatments. They protect and empower their survival behind strong biofilm architecture that works as their armor toward antimicrobial therapy. Additionally, P. aeruginosa generates virulence factors, contributing to chronic infection and recalcitrant phenotypic characteristics. The current study utilizes the benevolence of nanotechnology to develop an alternate technique to control the spreading of P. aeruginosa by limiting its biofilm and virulence development. This study used a natural compound, tetramethylpyrazine, to generate gold nanoparticles. Tetramethylpyrazine-gold nanoparticles (Tet-AuNPs) were presented in spherical shapes, with an average size of 168 ± 52.49 nm and a zeta potential of -12.22 ± 2.06 mV. The minimum inhibition concentration (MIC) of Tet-AuNPs that proved more than 90 % effective in inhibiting P. aeruginosa was 256 μg/mL. Additionally, it also shows antibacterial activities against Staphylococcus aureus (MIC, 256 μg/mL), Streptococcus mutans (MIC, 128 μg/mL), Klebsiella pneumoniae (MIC, 128 μg/mL), Listeria monocytogenes (MIC, 256 μg/mL), and Escherichia coli (MIC, 256 μg/mL). The sub-MIC values of Tet-AuNPs significantly inhibited the early-stage biofilm formation of P. aeruginosa. Moreover, this concentration strongly affected hemolysis, protease activity, and different forms of motilities in P. aeruginosa. Additionally, Tet-AuNPs destroyed the well-established mature biofilm of P. aeruginosa. The expression of genes linked with the biofilm formation and virulence in P. aeruginosa treated with sub-MIC doses of Tet-AuNPs was shown to be significantly suppressed. Gene expression studies support biofilm- and virulence-suppressing effects of Tet-AuNPs at the phenotypic level.

Sustainable Utilization of Food Biowaste (Papaya Peel) Extract for Gold Nanoparticle Biosynthesis and Investigation of Its Multi-Functional Potentials

Papaya contains high amounts of vitamins A, C, riboflavin, thiamine, niacin, ascorbic acid, potassium, and carotenoids. It is confirmed by several studies that all food waste parts such as the fruit peels, seeds, and leaves of papaya are potential sources of phenolic compounds, particularly in the peel. Considering the presence of numerous bioactive compounds in papaya fruit peels, the current study reports a rapid, cheap, and environmentally friendly method for the production of gold nanoparticles (AuNPs) employing food biowaste (vegetable papaya peel extract (VPPE)) and investigated its antioxidant, antidiabetic, tyrosinase inhibition, anti-inflammatory, antibacterial, and photocatalytic degradation potentials. The phytochemical analysis gave positive results for tannins, saponins, steroids, cardiac steroidal glycoside, protein, and carbohydrates. The manufactured VPPE-AuNPs were studied by UV-Vis scan (with surface plasmon resonance of 552 nm), X-ray diffraction analysis (XRD) (with average crystallite size of 44.41 nm as per the Scherrer equation), scanning electron microscopy-energy-dispersive X-ray (SEM-EDS), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), particle size, zeta potential, etc. The mean dimension of the manufactured VPPE-AuNPs is 112.2 d.nm (PDI-0.149) with a -26.1 mV zeta potential. The VPPE-AuNPs displayed a significant antioxidant effect (93.24% DPPH scavenging and 74.23% SOD inhibition at 100 µg/mL); moderate tyrosinase effect (with 30.76%); and substantial α-glucosidase (95.63%) and α-amylase effect (50.66%) at 100 µg/mL. Additionally, it was found to be very proficient in the removal of harmful methyl orange and methylene blue dyes with degradation of 34.70% at 3 h and 24.39% at 5 h, respectively. Taken altogether, the VPPE-AuNPs have been proven to possess multiple biopotential activities, which can be explored by the food, cosmetics, and biomedical industries.

The impact of pH and temperature on the green gold nanoparticles preparation using Jeju Hallabong peel extract for biomedical applications

The utilization of gold nanoparticles (AuNPs) has garnered significant attention in recent times, particularly in the field of biomedical research. The utilization of AuNPs in chemical synthesis procedures raises apprehensions regarding their potential toxicity in living organisms, which is inconsistent with their purported eco-friendly and cost-effective aspects. In this investigation, AuNPs were synthesized via the green synthesis approach utilizing Jeju Hallabong peel extract (HPE), a typical fruit variety indigenous to South Korea. The visible-range absorption spectrum of gold nanoparticles from green synthesis (HAuNPs) that are red wine in color occurs at a wavelength of λ = 517 nm. The morphology and particle size distribution were analysed using transmission electron microscopy (TEM) and ImageJ software. The TEM images reveal that the HAuNPs exhibit a high degree of dispersion and uniformity in their spherical shape, with an average size of approximately 7 nm. Moreover, elevating the initial pH level of the mixed solution has an impact on the decrease in particle dimensions, as evidenced by the blue shift observed in the UV-visible spectroscopy absorbance peak. Elevating the reaction temperature may accelerate the synthesis duration. However, it does not exert a substantial impact on the particle dimensions. The outcomes of an avidin-biocytin colorimetric assay provide preliminary analyses of possible sensor tunability using HAuNPs. The cytotoxicity of HAuNPs was evaluated through in vitro studies using the MTT assay on RAW 264.7 cell lines. The results indicated that the HAuNPs exhibited lower cytotoxicity compared to both chemically reduced gold nanoparticles (CAuNPs).

Alkaline protease functionalized hydrothermal synthesis of novel gold nanoparticles (ALPs-AuNPs): A new entry in photocatalytic and biological applications

Researchers are consistently investigating novel and distinctive methods and materials that are compatible for human life and environmental conditions This study aimed to synthesize gold nanoparticles (ALPs-AuNPs) using for the first time an alkaline protease (ALPs) derived from Phalaris minor seed extract. A series of physicochemical techniques were used to inquire the formation, size, shape and crystalline nature of ALPs-AuNPs. The nanoparticles' ability to degrade methylene blue (MB) through photocatalysis under visible light irradiation was assessed. The findings demonstrated that ALPs-AuNPs exhibited remarkable efficacy by destroying 100 % of MB within a mere 30-minute irradiation period. In addition, the ALPs-AuNPs demonstrated remarkable effectiveness in inhibiting the growth of gram-positive (S. aureus) and gram-negative (E. coli) bacteria. The inhibition zones examined against the two bacterial strains were 23(±0.3) mm and 19(±0.4); 13(±0.3) mm and 11(±0.5) mm under light and dark conditions respectively. The ALPs-AuNPs exhibited significant antioxidant activity by effectively scavenging 88 % of stable and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. As a result, the findings demonstrated that the environmentally friendly ALPs-AuNPs showed a strong potential for MB degradation and bacterial pathogen treatment.

Antibiofilm and antivirulence activities of laminarin-gold nanoparticles in standard and host-mimicking media

The rapidly rising antimicrobial resistance (AMR) in pathogenic bacteria has become one of the most serious public health challenges, with a high death rate. Most pathogenic bacteria have been recognized as a source of AMR and a primary barrier to antimicrobial treatment failure due to the development of biofilms and the production of virulence factors. In this work, nanotechnology was employed as a substitute method to control the formation of biofilms and attenuate virulence features in Pseudomonas aeruginosa and Staphylococcus aureus. We synthesized biocompatible gold nanoparticles from marine-derived laminarin as potential biofilm and virulence treatments. Laminarin-gold nanoparticles (Lam-AuNPs) have been identified as spherical, 49.84 ± 7.32 nm in size and - 26.49 ± 1.29 mV zeta potential. The MIC value of Lam-AuNPs against several drug-resistant microbial pathogens varied from 2 to 1024 μg/mL in both standard and host-mimicking media. Sub-MIC values of Lam-AuNPs were reported to effectively reduce the production of P. aeruginosa and S. aureus biofilms in both standard and host-mimicking growth media. Furthermore, the sub-MIC of Lam-AuNPs strongly reduced hemolysis, pyocyanin, pyoverdine, protease, and several forms of flagellar and pili-mediated motility in P. aeruginosa. Lam-AuNPs also inhibited S. aureus hemolysis and the production of amyloid fibrils. The Lam-AuNPs strongly dispersed the preformed mature biofilm of these pathogens in a dose-dependent manner. The Lam-AuNPs would be considered an alternative antibiofilm and antivirulence agent to control P. aeruginosa and S. aureus infections. KEY POINTS: • Lam-AuNPs were biosynthesized to control biofilm and virulence. • Lam-AuNPs show effective biofilm inhibition in standard and host-mimicking media. • Lam-AuNPs suppress various virulence factors of P. aeruginosa and S. aureus.

In silico description of the adsorption of cell signaling pathway proteins ovalbumin, glutathione, LC3, TLR4, ASC PYCARD, PI3K and NF-Kβ on 7.0 nm gold nanoparticles: obtaining their Lennard-Jones-like potentials through docking and molecular mechanics

The impact of vaccination on the world's population is difficult to calculate. For developing different types of vaccines, adjuvants are substances added to vaccines to increase the magnitude and durability of the immune response and the effectiveness of the vaccine. This work explores the potential use of spherical gold nanoparticles (AuNPs) as adjuvants. Thus, we employed docking techniques and molecular mechanics to describe how a AuNP 7.0 nm in diameter interacts with cell signaling pathway proteins. Initially, we used X-ray crystallization data of the proteins ovalbumin, glutathione, LC3, TLR4, ASC PYCARD, PI3K, and NF-Kβ to study the adsorption with an AuNP through molecular docking. Therefore, interaction energies were obtained for the AuNP complexes and individual proteins, as well as the AuNP and OVA complex (AuNP@OVA) with each cellular protein, respectively. Results showed that AuNPs had the highest affinity for OVA individually, followed by glutathione, ASC PYCARD domain, LC3, PI3K, NF-Kβ, and TLR4. Furthermore, when evaluating the AuNP@OVA complex, glutathione showed a greater affinity with more potent interaction energy when compared to the other studied systems.

Green Approach for the Simultaneous Synthesis and Separation of Gold Nanoparticles

Gold nanoparticles (AuNPs) have diagnostic and therapeutic applications as they are biocompatible and can be surface-functionalized. The use of organic solvents in the synthesis of AuNPs hampers their applications in the medicinal field. The large-scale production of nanoparticles requires their simultaneous synthesis and separation. Self-assembly of nanoparticles at the fluid-fluid interface facilitates their separation from the bulk and eliminates a downstream processing step. In this work, we exploit this in an aqueous two-phase system (ATPS) to synthesize and separate stable AuNPs. The ATPS was based on polyethylene glycol (PEG) and trisodium citrate dihydrate (citrate) as both these compounds can reduce Au ions. After the synthesis of nanoparticles, using one of the solutes, a complementary solution containing the other solute is added to form a two-phase system to facilitate self-assembly at the interface. The nanoparticles synthesized in different phases are characterized using UV-visible spectroscopy, scanning electron microscopy, and transmission electron microscopy. The AuNPs synthesized using the citrate solution are found to be unstable. Particles synthesized using the ATPS with PEG-600 are trapped at the interface while those using PEG-6000 remain in the bulk. Continuous synthesis and separation of nanoparticles in slug flow in a millichannel are demonstrated as a first step for large-scale controlled synthesis.

Statistical optimization and characterization of monodisperse and stable biogenic gold nanoparticle synthesis using Streptomyces sp. M137-2

Microbial synthesis of gold nanoparticles (AuNPs), which are used in various forms with different properties in medicine, as a renewable bioresource has become increasingly important in recent years. In this study, statistical optimization of stable and monodispersed AuNPs synthesis was performed using a cell-free fermentation broth of Streptomyces sp. M137-2 and AuNPs were characterized, and their cytotoxicity was determined. The three factors determined as pH, gold salt (HAuCl₄) concentration, and incubation time, which are effective in the extracellular synthesis of biogenic AuNPs, were optimized by Central Composite Design (CCD) and then UV-Vis Spectroscopy, Dynamic Light Scattering (DLS), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Scanning Transmission Electron Microscope (STEM), size distribution, Fourier-Transform Infrared (FT-IR) Spectroscopy, X-Ray Photoelectron Spectrophotometer (XPS) and stability analyzes of AuNPs were carried out. Optimum values of the factors were determined as pH 8, 10^- 3 M HAuCl₄, and 72 h incubation using Response Surface Methodology (RSM). Almost spherical AuNPs with 20-25 nm protein corona on the surface, 40-50 nm in size, monodisperse, and highly stable form were synthesized. Biogenic AuNPs were confirmed from characteristic diffraction peaks in the XRD pattern, UV-vis peak centred at 541 nm. The FT-IR results confirmed the role of Streptomyces sp. M137-2 metabolites in the reduction and stabilization of AuNPs. The cytotoxicity results also showed that AuNPs obtained using Streptomyces sp. can be used safely in medicine. This is the first report to perform statistical optimization of size-dependent biogenic AuNPs synthesis using a microorganism.

Biogenic synthesis of gold nanoparticles using Satureja rechingeri Jamzad: a potential anticancer agent against cisplatin-resistant A2780CP ovarian cancer cells

Drug resistance of cancer cells is a major issue in cancer treatment. Plant-mediated nanoparticle synthesis has been applied in recent years to overcome this problem. In this study, the biogenic synthesis of AuNPs was explored using Satureja rechingeri Jamzad aqueous leaf extract, and their anticancer effects were evaluated in cisplatin-resistant A2780CP ovarian cancer cells. The chemical composition of S. rechingeri Jamzad was analyzed using gas chromatography-mass spectrometry. The characteristics of green-synthesized AuNPs were confirmed using XRD, FTIR, UV-visible spectroscopy, TEM, SEM, EDX, DLS, and zeta potential. The cytotoxic effects of AuNPs and S. rechingeri Jamzad aqueous extract on cisplatin-resistant A2780CP ovarian cancer cells were evaluated by MTT assay and flow cytometry. Real-time PCR analyzed gene expression. The chemical composition revealed that carvacrol (89%) was the main component of the S. rechingeri Jamzad extract. The average size of the spherical biosynthesized AuNPs was 15.1 ± 3.7 nm. The AuNPs and plant extract inhibited the growth of cisplatin-resistant ovarian cancer cells in a time- and dose-dependent manner. The apoptotic cell death was confirmed by flow cytometry and DAPI staining. The proapoptotic genes were upregulated, while anti-apoptotic and metastatic genes were downregulated. According to the cell cycle analysis, cancer cells were arrested in the G0/G1 phase. Considering the anticancer activity of the synthesized AuNPs using S. rechingeri Jamzad and the low side effects of AuNPs on normal cells, these AuNPs showed strong potential for use as biological agents in drug-resistant cancer cells treatment.

Apoptotic effects of Phlomis armeniaca mediated biosynthesized silver nanoparticles in monolayer (2D) and spheroid (3D) cultures of human breast cancer cell lines

The purpose of current research was to assess the apoptotic effects of biofabrication silver nanoparticles (AgNPs) mediated by the aqueous extract of Phlomis armeniaca on human breast cancer cells (MCF-7 and MDA-MB-231) in monolayer (2D) and spheroid (3D) cultures. The biosynthesized AgNPs were characterized by UV-Vis spectrophotometer (the peaks of resonances at 432 nm), scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS). 1-20 µM/mL AgNPs were applied to MCF-7 and MDA-MB-231 cell lines to determine IC50 values at 24, 48 and 72nd h and were found to be 10 µM/mL for both cell lines. Immunohistochemical staining results of BrdU, TUNEL, caspase-3 and Endo G in both 2D and 3D cultures and gene expression levels of caspases (caspase-3, -8 and -9) and Endo G were evaluated. Moreover, the total oxidant/antioxidant status (TOS-TAS) due to AgNPs application in both cell culture mediums was evaluated. AgNPs treatment results in both cell lines in both 2D and 3D cultures showed a significant decrease in the BrdU labeling index, while large amounts of cells were labelled with TUNEL and Endo G. In 2D culture, Endo G expression increased in MCF-7 cells at 48 and 72nd hours, while it increased significantly in MDA-MB-231 cells at all hours. OSI results show that ROS production is increased in cell medium treated with AgNPs. In conclusion, AgNPs mediated by Phlomis armeniaca, synthesized by a green method, successfully induced damage to mitochondria, resulting in cell cycle arrest and consequent cell proliferation blockade and death in both MCF-7 and MDA-MB-231 cells.