Fungal biomolecules assisted biosynthesis of Au-Ag alloy nanoparticles and evaluation of their catalytic property

Eco-Friendly Synthesis, Characterization, and Biomedical Applications of Biosynthesized Bimetallic Silver-Gold Nanoparticles by Culture Supernatant of Aspergillus niger

Green synthesis of bimetallic nanoparticles of noble metals is highly desirable in nanomedicine because of their potential use as anticoagulant, thrombolytic and anticancer agents. In this study, it was discovered that the filamentous fungus Aspergillus niger proved effective in producing bimetallic Ag-Au nanoparticles. A. niger culture supernatant was able to produce Ag-AuNPs by reducing the solution of chloroauric acid/silver nitrate (1.0:1.0 mM) within 2 min at 100 °C and pH 8. Experimental Ag-AuNP detection was performed by visually observing the color change to reddish brown. The produced nanoparticles displayed maximal absorbance at 530 nm in UV-vis spectroscopy. According to transmission electron microscopy, most of the nanoparticles were spherical, with a mean diameter of 8-10 nm. The biosynthesis of Ag-AuNPs by A. niger was confirmed by Fourier transform infrared spectroscopy, X-ray diffraction and energy dispersive X-ray analytical techniques. Its zeta potential was discovered to be -34.01 mV. The biosynthesized Ag-AuNPs exhibited effective thrombolytic and antiplatelet aggregation actions by totally preventing and dissolving the blood clot which was verified by microscopic examination, amelioration of blood coagulation assays, and carrageenan-induced tail thrombosis model. The findings verified the effectiveness of biosynthesized Ag-AuNPs as a powerful antitumor agent against HepG2 and A549 cell lines with IC50 values of 15.57 and 27.07 μg/mL, respectively. Crystal violet assay validated the cytopathic effects of Ag-AuNPs on A549 and HepG2 cell lines. Therefore, the produced Ag-AuNPs from A. niger are a promising candidate in the management of thrombosis.

Diversity of fungus-mediated synthesis of gold nanoparticles: properties, mechanisms, challenges, and solving methods

Fungi-mediated synthesis of Gold nanoparticles (AuNPs) has advantages in: high efficiency, low energy consumption, no need for extra capping and stabilizing agents, simple operation, and easy isolation and purification. Many fungi have been found to synthesize AuNPs inside cells or outside cells, providing different composition and properties of particles when different fungi species or reaction conditions are used. This is good to produce AuNPs with different properties, but may cause challenges to precisely control the particle shape, size, and activities. Besides, low concentrations of substrate and fungal biomass are needed to synthesize small-size particles, limiting the yield of AuNPs in a large scale. To find clues for the development methods to solve these challenges, the reported mechanisms of the fungi-mediated synthesis of AuNPs were summarized. The mechanisms of intracellular AuNPs synthesis are dependent on gold ions absorption by the fungal cell wall via proteins, polysaccharides, or electric absorption, and the reduction of gold ions via enzymes, proteins, and other cytoplasmic redox mediators in the cytoplasm or cell wall. The extracellular synthesis of AuNPs is mainly due to the metabolites outside fungal cells, including proteins, peptides, enzymes, and phenolic metabolites. These mechanisms cause the great diversity of the produced AuNPs in functional groups, element composition, shapes, sizes, and properties. Many methods have been developed to improve the synthesis efficiency by changing: chloroauric acid concentrations, reaction temperature, pH, fungal mass, and reaction time. However, future studies are still required to precisely control the: shape, size, composition, and properties of fungal AuNPs.

In situ engineering of Au-Ag alloy embedded PEDOT nanohybrids at a solvent/non-solvent interface for the electrochemical enzyme-free detection of histamine

Steadfast efforts have been made to develop novel materials and incorporate them into functional devices for practical applications, pushing the research on electroactive materials to the forefront of nano electronics. Liquid/liquid interface-assisted polymerization offers a scalable methodology to fabricate hybrid materials with multifunctional applications, in contrast to the conventional and ubiquitous routes. Here, we explored this efficient and versatile approach toward the in situ tailoring of Au-Ag alloy nanostructures with a conducting polymer, poly(3,4-ethylene-dioxythiophene) (PEDOT). With the appropriate choice of organic and inorganic phases for the distribution of monomer and oxidant, the miscibility restraints of the reactants in a single phase were alleviated. Effective nanostructure tuning of highly crystalline and electroactive PEDOT/Au-Ag alloy has been achieved by varying the molar ratio of Au³⁺/Ag⁺ in the reaction mixture. The as-synthesized composite is further explored to detect neuromodulator histamine (HA), which displays high sensitivity with a limit of detection (LOD) of 1.5 nM, and selectivity even in the presence of various interfering analogs of 10-fold concentration. Subsequently, density functional theory (DFT) simulations are employed to assess the mode of interaction between HA and the electroactive surfaces. The competency to detect HA in preserved food entails its potential in food spoilage monitoring. Furthermore, the detection of histamine generated by sub-cultured human neuronal cells SH-SY5Y proves its practical viability in health monitoring devices.

Polymeric micelles and cancer therapy: an ingenious multimodal tumor-targeted drug delivery system

Since the beginning of pharmaceutical research, drug delivery methods have been an integral part of it. Polymeric micelles (PMs) have emerged as multifunctional nanoparticles in the current technological era of nanocarriers, and they have shown promise in a range of scientific fields. They can alter the release profile of integrated pharmacological substances and concentrate them in the target zone due to their improved permeability and retention, making them more suitable for poorly soluble medicines. With their ability to deliver poorly soluble chemotherapeutic drugs, PMs have garnered considerable interest in cancer. As a result of their remarkable biocompatibility, improved permeability, and minimal toxicity to healthy cells, while also their capacity to solubilize a wide range of drugs in their micellar core, PMs are expected to be a successful treatment option for cancer therapy in the future. Their nano-size enables them to accumulate in the tumor microenvironment (TME) via the enhanced permeability and retention (EPR) effect. In this review, our major aim is to focus primarily on the stellar applications of PMs in the field of cancer therapeutics along with its mechanism of action and its latest advancements in drug and gene delivery (DNA/siRNA) for cancer, using various therapeutic strategies such as crossing blood-brain barrier, gene therapy, photothermal therapy (PTT), and immunotherapy. Furthermore, PMs can be employed as "smart drug carriers," allowing them to target specific cancer sites using a variety of stimuli (endogenous and exogenous), which improve the specificity and efficacy of micelle-based targeted drug delivery. All the many types of stimulants, as well as how the complex of PM and various anticancer drugs react to it, and their pharmacodynamics are also reviewed here. In conclusion, commercializing engineered micelle nanoparticles (MNPs) for application in therapy and imaging can be considered as a potential approach to improve the therapeutic index of anticancer drugs. Furthermore, PM has stimulated intense interest in research and clinical practice, and in light of this, we have also highlighted a few PMs that have previously been approved for therapeutic use, while the majority are still being studied in clinical trials for various cancer therapies.

Application of Selenium Nanoparticles in Localized Drug Targeting for Cancer Therapy

BACKGROUND

Selenium nanoparticles (SeNPs) have gardened their place in the biomedical field and serve as a chemotherapeutic agent for targeted drug delivery due to their capacity to exert distinct mechanisms of action on cancer and normal cells. The principle behind these mechanisms is the generation of Reactive Oxygen Species (ROS) eventually leads to apoptosis via the dysfunction of various pathways. SeNPs, when used in higher concentrations, lead to toxicity; therefore, conjugation and surface functionalization not only improve their toxic nature but also enhance their anticancer activity.

OBJECTIVES

The primary goal of this analysis is to provide a thorough and systematic investigation into the use of various SeNPs in localized drug targeting for cancer therapy. This has been achieved by citing examples of numerous SeNPs and their use as a drug targeting agent for cancer therapy.

METHODS

All relevant data and information about the various SeNPs for drug targeting in cancer therapy were gathered from various databases, including Science Direct, PubMed, Taylor and Francis imprints, American Chemical Society, Springer, Royal Society of Chemistry, and Google scholar.

RESULTS

SeNPs are explored due to their better biopharmaceutical properties and their cytostatic behavior. Se, as an essential component of the enzyme glutathione peroxidase (GPx) and other seleno-chemical substances, might boost chemotherapeutic efficacy, and protect tissues from cellular damage caused by ROS. SeNPs have the potential to set the stage for developing new strategies to treat malignancy.

CONCLUSION

This review extensively analyzed the anticancer efficacy and functionalization strategies of SeNPs in drug delivery to cancer cells. In addition, this review highlights the mechanism of action of drug-loaded SeNPs to suppress the proliferation of cancer cells in different cell lines.

Phytosynthesis of Palladium Nanoclusters: An Efficient Nanozyme for Ultrasensitive and Selective Detection of Reactive Oxygen Species

Hydrogen peroxide is a low-reactivity reactive oxygen species (ROS); however, it can easily penetrate cell membranes and produce highly reactive hydroxyl radical species through Fenton’s reaction. Its presence in abnormal amounts can lead to serious diseases in humans. Although the development of a simple, ultrasensitive, and selective method for H₂O₂ detection is crucial, this remains a strategic challenge. The peroxidase mimetic activity of palladium nanoclusters (PdNCs) has not previously been evaluated. In this study, we developed an ultrasensitive and selective colorimetric detection method for H₂O₂ using PdNCs. An unprecedented eco-friendly, cost-effective, and facile biological method was developed for the synthesis of PdNCs. This is the first report of the biosynthesis of PdNCs. The synthesized nanoclusters had a significantly narrow size distribution profile and high stability. The nanoclusters were demonstrated to possess a peroxidase mimetic activity that could oxidize peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB). Various interfering substances in serum (100 μM phenylalanine, cysteine, tryptophan, arginine, glucose, urea, Na⁺, Fe²⁺, PO₄³⁻, Mn⁺², Ca²⁺, Mg²⁺, Zn²⁺, NH₄⁺, and K⁺) were included to evaluate the selectivity of the assay, and oxidation of TMB occurred only in the presence of H₂O₂. Therefore, PdNCs show an efficient nanozyme for the peroxidase mimetic activity. The assay produced a sufficient signal at the ultralow concentration of 0.0625 µM H₂O₂. This colorimetric assay provides a real-time, rapid, and easy-to-use platform for the detection of H₂O₂ for clinical purposes.

Enzyme Mimetic Activity of ZnO-Pd Nanosheets Synthesized via a Green Route

Recent developments in the area of nanotechnology have focused on the development of nanomaterials with catalytic activities. The enzyme mimics, nanozymes, work efficiently in extreme pH and temperature conditions, and exhibit resistance to protease digestion, in contrast to enzymes. We developed an environment-friendly, cost-effective, and facile biological method for the synthesis of ZnO-Pd nanosheets. This is the first biosynthesis of ZnO-Pd nanosheets. The synthesized nanosheets were characterized by UV-visible spectroscopy, X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray. The d-spacing (inter-atomic spacing) of the palladium nanoparticles in the ZnO sheets was found to be 0.22 nm, which corresponds to the (111) plane. The XRD pattern revealed that the 2θ values of 21.8°, 33.3°, 47.7°, and 56.2° corresponded with the crystal planes of (100), (002), (112), and (201), respectively. The nanosheets were validated to possess peroxidase mimetic activity, which oxidized the 3,3',5,5'-tetramethylbenzidine (TMB) substrate in the presence of H2O2. After 20 min of incubation time, the colorless TMB substrate oxidized into a dark-blue-colored one and a strong peak was observed at 650 nm. The initial velocities of Pd-ZnO-catalyzed TMB oxidation by H2O2 were analyzed by Michaelis-Menten and Lineweaver-Burk plots, resulting in 64 × 10-6 M, 8.72 × 10-9 Msec-1, and 8.72 × 10-4 sec-1 of KM, Vmax, and kcat, respectively.

Reclamation of hexavalent chromium using catalytic activity of highly recyclable biogenic Pd(0) nanoparticles

Hexavalent chromium is extremely toxic and increasingly prevalent owing to industrialisation, thereby posing serious human health and environmental risks. Therefore, new approaches for detoxifying high concentrations of Cr (VI) using an ultralow amount of catalyst with high recyclability are increasingly being considered. The catalytic conversion of Cr (VI) into Cr (III) was previously reported; however, it required a large amount of catalyst to reduce a low concentration of Cr (VI); further, pH adjustment and catalyst separation had to be performed, causing issues with large-scale remediation. In this study, an unprecedented eco-friendly and cost-effective method was developed for the synthesis of Pd nanoparticles (PdNPs) with a significantly narrow size distribution of 3-25 nm. PdNPs demonstrated the presence of elemental Pd with the zero oxidation state when analysed by energy-dispersive X-ray analysis and X-ray photoelectron spectroscopy. The PdNPs could detoxify a high concentration of Cr (VI), without the need to adjust the pH or purify the nanoparticles for reusability. The reusability of the PdNPs for the catalytic conversion of Cr (VI) into Cr (III) was >90% for subsequent cycles without the further addition of formic acid. Thus, the study provides new insights into the catalytic reclamation of Cr (VI) for industrial wastewater treatment.

Facile Synthesis of Triangular and Hexagonal Anionic Gold Nanoparticles and Evaluation of Their Cytotoxicity

Comprehension of the shape-dependent properties of gold nanoparticles (AuNPs) could benefit the advancements in cellular uptake efficiency. Spherical AuNPs have generally been used for drug delivery, and recent research has indicated that the cellular uptake of triangular AuNPs was higher than that of spherical ones. Previous reports have also revealed that chemically synthesized AuNPs were cytotoxic. Therefore, we have developed a facile, cost-effective, and environmentally friendly method for synthesizing triangular and hexagonal anionic AuNPs. The zeta potential of the synthesized AuNPs was negative, which indicated that their surface could be easily functionalized with positively charged molecules to upload drugs or biomolecules. Transmission electron microscopy (TEM) images illustrated that the largest particle size of the synthesized quasi-hexagonal AuNPs was 61 nm. The TEM images also illustrated that two types of equilateral-triangular AuNPs were synthesized: One featured sharp and the other rounded corners. The sides of the smallest and largest triangular AuNPs were 23 and 178 nm, respectively. Energy-dispersive X-ray spectra of the green-synthesized AuNPs indicated that they consisted entirely of elemental Au. The cytotoxicity of the green-synthesized AuNPs was evaluated using 3T3-L1 adipocytes. Using cell viability data, we determined that the green-synthesized AuNPs did not exhibit any cytotoxic effects on 3T3-L1 adipocytes.

Biosynthesis of silver nanoparticles using Azadirachta indica leaves: characterisation and impact on Staphylococcus aureus growth and glutathione‐S‐transferase activity

Silver nanoparticles (AgNPs) are toxic to various microbes, but the mechanism of action is not fully understood. The present report explores Azadirachta indica leaf extract as a reducing agent for the rapid biosynthesis of AgNPs. The effects of AgNPs on the growth, glutathione‐S‐transferase (GST) activity, and total protein concentration in Staphylococcus aureus were investigated, as was its antibacterial activity against seven other bacterial strains. Nanoparticle synthesis was confirmed by the UV‐Vis spectrum and colour change of the solution. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential analysis, and infrared spectroscopy were used to characterise the synthesised nanoparticles. The UV‐Visible spectrograph showed an absorbance peak at 420 nm. DLS analysis showed an average AgNP size of 159 nm and a Polydispersity Index of 0.373. SEM analysis showed spherical particle shapes, while TEM established an average AgNP size of 7.5 nm. The element analysis profile showed small peaks for calcium, potassium, zinc, chlorine, with the presence of oxygen and silver. AgNPs markedly affected the growth curves and GST activity in treated bacteria, and produced moderate antibacterial activity. Thus AgNPs synthesised from A. indica leaves can interrupt the growth curve and total protein concentration in bacterial cells.

Biogenic nanomaterials: Synthesis, characterization, growth mechanism, and biomedical applications

The biosynthesis of nanomaterials is a huge and intensifying field of research due to their application in various areas, in particular the biomedical and pharmaceutical fields. In this review, we focused on the biosynthesis of both metallic and semiconductor nanomaterials and their application in biomedicine and pharmaceutics. In order to meet an exponentially increasing need for nanostructured materials, the biological route for the synthesis of nanomaterials will have to be explored, offering advantages over chemical and physical methods as a simpler, more cost effective, and environmentally friendly method, and for which there is no need to use high pressure and temperatures or toxic chemicals. This review discusses in detail the potential role of bioreducing and capping/stabilizing agents in biosynthesis. This review also investigates the application of various biosynthetic nanomaterials as antimicrobial materials, in clinical detection, for drug delivery and wound-healing, and as anti-diabetic materials.

Antibacterial and catalytic activity of biogenic gold nanoparticles synthesised by Trichoderma harzianum

This study reveals the antibacterial and catalytic activity of biogenic gold nanoparicles (AuNPs) synthesised by biomass of Trichoderma harzianum. The antibacterial activity of AuNPs was analysed by the means of growth curve, well diffusion and colony forming unit (CFU) count methods. The minimum inhibitory concentration of AuNPs was 20 µg/ml. AuNPs at 60 µg/ml show effective antibacterial activity as optical absorption was insignificant. The well diffusion and CFU methods were also applied to analyse the effect of various concentration of AuNPs. Further, the catalytic activity of AuNPs was analysed against methylene blue (MB) as a model pollutant in water. MB was degraded 39% in 30 min in the presence of AuNPs and sodium borohydrate and the rate constant (k) was found to be 0.2 × 10-3 s-1. This shows that the biogenic AuNP is an effective candidate for antibacterial and catalytic degradation of toxic pollutants.

Biocompatible silver, gold and silver/gold alloy nanoparticles for enhanced cancer therapy: in vitro and in vivo perspectives

The aims of nano oncology are to detect, target and treat cancer cells without any side effects. The present study describes the microbial synthesis of biocompatible nanoparticles of silver (AgNPs), gold (AuNPs) and their alloy (Ag/AuNPs) for hepatoprotective activity against diethylnitrosamine (DEN)-induced liver cancer in a Sprague Dawley (SD) rat model. The crystalline nature and physicochemical features of the nanoparticles were identified by Fourier transform infra-red (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) analysis. Based on the instrumental analysis, the synthesised nanomaterials were found to be spherical in shape and have an average size in the nano region. Nitrate reductase was characterized after partial purification of the culture filtrate via polyacrylamide gel electrophoresis and its molecular weight was determined as ∼45 kDa. Furthermore, the IC₅₀ values of the AgNPs, AuNPs and Ag/AuNPs on HepG2 cells were determined as 38.42 μg ml^-1, 43.25 μg ml^-1 and 39.20 μg ml^-1, respectively, and the antioxidant potential of the nanoparticles was also systematically analyzed. The No-Observed-Adverse-Effect-Level (NOAEL) for the AgNPs was determined to be 2000 mg per kg of body weight (bw) from an acute toxicity test. Similarly, the NOAEL of AuNPs and Ag/AuNPs were calculated as 1000 mg per kg bw. Based on the in vivo studies, a significant tumour reduction (∼45 to 65%) was observed in the nanoparticle-treated animals, which was further confirmed by hematological, biochemical, TEM and histopathological analysis. Immunohistochemistry analysis confirmed the presence of BAX antibodies, up to immunoreactive (3+) level in treated animals. These results strongly suggest the potential anticancer activities of AgNPs, AuNPs and Ag/AuNPs against DEN-induced liver cancer and they could be potential candidates for effective nano drug development.

Green synthesis of highly stable carbon nanodots and their photocatalytic performance

The present study reports a novel, facile, biosynthesis route for the synthesis of carbon nanodots (CDs) with an approximate quantum yield of 38.5%, using Musk melon extract as a naturally derived-precursor material. The synthesis of CDs was established by using ultraviolet-visible (UV-vis) spectroscopy, Dynamic light scattering, photoluminescence spectroscopy, X-ray diffraction, transmission electron microscopy and Fourier transform infrared (FTIR) spectroscopy. The as-prepared CDs possess an eminent fluorescence under UV-light (λ_ex = 365 nm). The size range of CDs was found to be in the range of 5-10 nm. The authors further explored the use of such biosynthesised CDs as a photocatalyst material for removal of industrial dye. Degradation of methylene blue dye was performed in a photocatalytic reactor and monitored using UV-vis spectroscopy. The CDs show excellent dye degradation capability of 37.08% in 60 min and reaction rate of 0.0032 min^-1. This study shows that synthesised CDs are highly stable in nature, and possess potential application in wastewater treatment.

Catalytic Degradation of Dichlorvos Using Biosynthesized Zero Valent Iron Nanoparticles

The removal of dichlorvos contamination from water is a challenging task because of the presence of direct carbon to phosphorous covalent bond, which makes them resistant to chemical and thermal degradation. Although there have been reports in the literature for degradation of dichlorvos using nanomaterials, those are based on photocatalysis. In this paper, we report a simple and rapid method for catalytic degradation of dichlorvos using protein-capped zero valent iron nanoparticles (FeNPs). We have developed an unprecedented reliable, clean, nontoxic, eco-friendly, and cost-effective biological method for the synthesis of uniformly distributed FeNPs. Yeast extract was used as reducing and capping agent in the synthesis of FeNPs, and synthesized particles were characterized by the UV-visible spectroscopy, X -ray diffraction, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). TEM micrographs reveal that the nanoparticles size is distributed in the range of 2-10 nm. Selected area electron diffraction pattern shows the polycrystalline rings of FeNPs. The mean size was found to be 5.006 nm from ImageJ. FTIR spectra depicted the presence of biomolecules, which participated in the synthesis and stabilization of nanoparticles. As synthesized, FeNPs were used for the catalytic degradation of dichlorvos in aqueous medium. The degradation activity of the FeNPs has been investigated by the means of incubation time effect, oxidant effect, and nanoparticle concentration effect. The ammonium molybdate test was used to confirm the release of phosphate ions during the interaction of dichlorvos with FeNPs.

In vitro antimicrobial and in vivo wound healing effect of actinobacterially synthesised nanoparticles of silver, gold and their alloy

Antibacterial, antifungal and wound healing potential of actinobacterially synthesised Ag, Au and Ag/Au nanoparticles.

Catalytic degradation of methylene blue by biosynthesised copper nanoflowers using F. benghalensis leaf extract

This study reports the unprecedented, novel and eco-friendly method for the synthesis of three-dimensional (3D) copper nanostructure having flower like morphology using leaf extract of Ficus benghalensis. The catalytic activity of copper nanoflowers (CuNFs) was investigated against methylene blue (MB) used as a modal dye pollutant. Scanning electron micrograph evidently designated 3D appearance of nanoflowers within a size range from 250 nm to 2.5 μm. Energy-dispersive X-ray spectra showed the presence of copper elements in the nanoflowers. Fourier-transform infrared spectra clearly demonstrated the presence of biomolecules which is responsible for the synthesis of CuNFs. The catalytic activity of the synthesised CuNFs was monitored by ultraviolet-visible spectroscopy. The MB was degraded by 72% in 85 min on addition of CuNFs and the rate constant (k) was found to be 0.77 × 10^-3 s^-1. This method adapted for synthesis of CuNFs offers a valuable contribution in the area of nanomaterial synthesis and in water research by suggesting a sustainable and an alternative route for removal of toxic solvents and waste materials.

Synthesis of silver nanoparticles from Metarhizium robertsii waste biomass extract after nonylphenol degradation, and their antimicrobial and catalytic potential

Waste biomass extracts of Metarhizium robertsii synthesize silver nanoparticles with high biocatalytic and antimicrobial activity.