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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. [ABSTRACT FROM AUTHOR]

Biosynthesis of gold nanoparticles (AuNPs) is emerging as a better alternative to traditional chemical-based techniques. During this study, extracts of different marine algae species Ulva rigida (green algae), Cystoseira myrica (brown Algae), and Gracilaria foliifera (red Algae) were utilized as reducing and capping agents to synthesize AuNPs. AuNPs capped by U. rigida, C. myrica, and G. foliifera were confirmed by the appearance of surface plasmonic bands at 528, 540, and 543 nm, respectively. Transmission electron microscopy revealed mostly spherical shapes of AuNPs having a size of about 9 nm, 11 nm, and 13 nm for C. myrica, and G. foliifera extracts, respectively. Fourier transform-infrared spectroscopy (FTIR) illustrated the major chemical constituents of U. rigida, C. myrica, and G. foliifera. LC50 values of the biosynthesized AuNPs against Artemia salina nauplii were calculated at a range of concentrations (5-188 μg ml−1) after 16 to 24h. AuNPs concentration-dependent lethality was noted and U. rigida extracts-mediated AuNPs presented the lowest cytotoxicity. The biosynthesized AuNPs exhibited significant anticancer activity (86.83%) against MCF-7 cell lines (human breast adenocarcinoma cell lines) at 188 µg/ml concentration. G. foliifera demonstrated the highest anticancer value (92.13%) followed by C. myrica (89.82%), and U. rigida (86.83%), respectively. The AuNPs synthesized by different algal extracts showed variable antimicrobial activity against the tested pathogenic microorganisms. AuNPs of U. rigida extracts showed significant antimicrobial activity against dermatophytic fungi Trichosporon cataneum (30 mm) followed by Trichophyton mantigrophytes (25 mm). Furthermore, it also exhibited mild activity against Escherichia coli (17 mm), Cryptococcus neoformans (15 mm), Candida albicans (13 mm), and Staphylococcus aureus (11mm), respectively whereas no effects were observed against Bacillus cereus. To conclude, AuNPs can be effectively synthesized by marine algal species, and particularly U. rigida extracts could be effective reducing agents for the green AuNPs synthesis. These AuNPs could potentially serve as efficient alternative anticancer agents against human breast adenocarcinoma and anti-dermatophytes associated with skin infections.

There is a growing need to improve facile, eco-friendly, and cheap approaches for nanoparticle (NP) synthesis. Green protocols have been investigated for the fabrication of NPs using several natural sources as plants, algae, fungi, and bacteria. Thus, the present study proposed a rapid, convenient, and efficient biosynthesis of gold NPs (Au-NPs) using the ethanolic extracts of three macroalgae, i.e., Cystoseira myrica, C. trinodis, and Caulerpa prolifera. The reduction of Au ions and the fabrication of Au-NPs were validated using ultraviolet-visible (UV–Vis) spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and zeta potential analysis. The produced Au-NPs were tested for their antibacterial, antifungal, anti-inflammatory, and schistolarvicidal activity. Results revealed the formation of Au-NPs with an average size of 12.6–15.5 nm and different shapes that are mainly spherical with pure crystalline nature. The strong antibacterial activities of C. trinodis– and C. myrica–based Au-NPs against E. coli (inhibition zones of 22 and 19 mm) and against Staphylococcus aureus (inhibition zones of 18 and 20.5 and mm) were recorded, respectively. On the other hand, the high antifungal activity of C. trinodis Au-NPs against Aspergillus niger and Alternaria alternate showed the inhibition zones of 18 and 17 mm, respectively. The high antifungal activity of C. trinodis Au-NPs against Candida albicans (inhibition zone 16 mm) was also recorded. Regarding anti-inflammatory and schistolarvicidal activity, Au-NPs fabricated using C. myrica showed 64.2% of the inhibitory effect on protein denaturation and recorded the highest schistolarvicidal activity against Schistosoma mansoni cercariae that sank and died after 7 min. Overall, these findings proved that macroalgal ethanolic extracts can be effectively used for the biosynthesis of Au-NPs. These Au-NPs offer a significant alternative antimicrobial, anti-inflammatory, and schistolarvicidal agents. for biomedical uses.

Biosynthesis of gold nanoparticles (AuNPs) is emerging as a better alternative to traditional chemical based techniques. During this study, extracts of different marine algae species Ulva rigida (green algae), Cystoseira myrica (brown Algae), and Gracilaria foliifera (red Algae) were utilized as reducing and capping agents to synthesize AuNPs. AuNPs capped by U. rigida, C. myrica, and G. foliifera were confirmed by the appearance of surface plasmonic bands at 528, 540, and 543 nm, respectively. Transmission electron microscopy revealed mostly spherical shapes of AuNPs having a size of about 9 nm, 11 nm, and 13 nm for C. myrica, and G. foliifera extracts, respectively. Fourier transform-infrared spectroscopy (FTIR) illustrated the major chemical constituents of U. rigida, C. myrica, and G. foliifera. LC50 values of the biosynthesized AuNPs against Artemia salina nauplii were calculated at a range of concentrations (5-188 μg ml−1) after 16 to 24h. AuNPs concentration-dependent lethality was noted and U. rigida extracts-mediated AuNPs presented the lowest cytotoxicity. The biosynthesized AuNPs exhibited significant anticancer activity (86.83%) against MCF-7 cell lines (human breast adenocarcinoma cell lines) at 188 μg/ml concentration. G. foliifera demonstrated the highest anticancer value (92.13%) followed by C. myrica (89.82%), and U. rigida (86.83%), respectively. The AuNPs synthesized by different algal extracts showed variable antimicrobial activity against the tested pathogenic microorganisms. AuNPs of U. rigida extracts showed significant antimicrobial activity against dermatophytic fungi Trichosporon cataneum (30 mm) followed by Trichophyton mantigrophytes (25 mm). Furthermore, it also exhibited mild activity against Escherichia coli (17 mm), Cryptococcus neoformans (15 mm), Candida albicans (13 mm), and Staphylococcus aureus (11mm), respectively whereas no effects were observed against Bacillus cereus. To conclude, AuNPs can be effectively synthesized by marine algal species, and particularly U. rigida extracts could be effective reducing agents for the green AuNPs synthesis. These AuNPs could potentially serve as efficient alternative anticancer agents against human breast adenocarcinoma and anti-dermatophytes associated with skin infections. [ABSTRACT FROM AUTHOR]

This study was performed to explore acute toxicity of biologically synthesized gold nanoparticles (AuNPs) to a model organism Daphnia magna. Hence, using aqueous extract of marine macroalga Saccharina japonica, two AuNPs including SJ-AuNPs-72 (72.6 ± 43.8 nm) and SJ-AuNPs-10 (10.8 ± 2.8 nm) were synthesized. These AuNPs were characterized by different techniques such as UV-Vis spectrophotometry, transmission electron microscopy (TEM), dynamic light scattering (DLS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDX). The 48-h LC50 values of SJ-AuNPs-72 and SJ-AuNPs-10 to D. magna were 1.57 ± 0.07 and 2.69 ± 0.12 mg/L, respectively, showing greater toxicity of SJ-AuNPs-72. After exposure of daphnids to treatments, AuNPs were accumulated in gut tract, and lipid droplets under the Daphnia carapace were also observed. Whereas studies on toxicity of biosynthesized AuNPs are still scarce, the achievements of this work are helpful for understanding the toxicity of biosynthesized AuNPs to crustacean D. magna. [ABSTRACT FROM AUTHOR]

The study incorporates the urea detection in non-enzymatic urea samples and enzymatic urea-urease samples utilizing the phenomenon of surface plasmon resonance (SPR)/localized surface plasmon resonance (LSPR) realized on the core of a multimoded optical fiber. The designed bio-sensor, primarily a refractive index sensor well operates for the urea detection in the concentrations ranging 50–800 mM. The experimental results show that as urea concentration increases in both samples (non-enzymatic and enzymatic), refractive indices also increases leading to a red shift in the resonance wavelength (SPR wavelength). Further, the sensing probe was modified by coating biosynthesized gold nanoparticles (AuNPs) on to the thin layer of gold (Au) by dipping the probe in the solution of biosynthesized AuNPs. After performing the experiments, the sensitivity values were calculated for solutions of different concentration of urea in non-enzymatic and enzymatic urea samples and compared with the probes coated with Au film only. A comparative study of the two set of results reveals a two-fold and three-fold enhancement in the sensitivity values for non-enzymatic and enzymatic urea samples respectively as compared with the probe without AuNPs. Authors believe that the present fiber optic bio sensing probe is easy to design, low cost, capable of remote sensing. Also it works well in the range near to the pathophysiological range of urea in human blood and hence can be beneficial for the determination of urea concentration in medical diagnostics as well. [ABSTRACT FROM AUTHOR]

Abstract: Biological systems employing microorganisms have been used as an alternative to conventional chemical techniques for synthesizing gold nanoparticles. In the present study, gold nanoparticles have been synthesized from the supernatant broth (SB) and live cell filtrate (LCF) of the industrially important fungus Penicillium rugulosum. Additionally, potato dextrose broth (PDB) medium which is used for the growth of the fungus has also been able to synthesize gold nanoparticles. The size of the particles has been investigated by Bio-TEM before purification as well as after purification to find the difference in morphology pattern of the nanoparticles. Different characterization techniques like X-ray diffraction (XRD), infra-red (FTIR), X-ray photoelectron (XPS) and UV–vis spectroscopy have been used for analysis of the particles. SB of the fungus has yielded nanoparticles with better morphology and hence further optimization studies were conducted for controlling the size and shape of the above by altering pH and concentration of gold salt. A pH range of 4–6 has favored the synthesis process whereas increasing concentration of gold salt (beyond 2mM) has resulted in the formation of bigger sized and aggregated nanoparticles. The optimized nanoparticles have been used to conjugate with isolated genomic DNA of bacteria Escherichia coli and Staphylococcus aureus. Visual observation of agarose gel electrophoresis images confirmed the binding of gold nanoparticles (4μL and 6μL) with isolated DNA (2μL) fragments of both the organisms. The slight red shift of the surface plasmon (SP) band and minor aggregations noticed in Bio-TEM images for the DNA conjugated gold nanoparticles indicates that the genomic DNA could stabilize the particles against aggregation owing to negatively charged phosphate backbone. [Copyright &y& Elsevier]

Abnormalities in apoptosis (More or less than normal rate) is a central factor to detect many human disorders such as many types of cancer and to show therapeutic potential of drugs. During apoptosis, oxidation of reduced gluthation (GSH) to its oxidized form, GSSG, results in a decreased GSH to GSSG ratio. Here, we used altered GSH/GSSG redox state and the release of Cyt c from mitochondria to cytosol as an indicator for apoptosis assay. This study reports a visual method for cell apoptosis assay through in-situ biosynthesized gold nanoparticles (AuNPs) inside livingcells, only after adding a sufficient amount of gold ion. After incubation of apoptotic and non-apoptotic cells with chloroauric acid solution, high level of GSH act as reducing agent in formation of AuNPs using thiol inside living non-apoptotic cells. While in the apoptotic cells, what's happening is based on changes in plasmonic coupling between AuNPs embedded along the oxidized gluthation and Cyt c aggregates in cytosol which causes color changes from red to purple. In this study, we successfully reported cell-based (inside a living cells) and cell free (cell lysis) methods for apoptosis assay of breast cancer cells and we achieved very good results in comparison with a standard apoptosis assay procedure. The linear range for MCF-7 cells detection from 30 to 3 × 105 cells/ml was obtained with a detection limit of 30 cells. In addition, the proposed approach is applicable to detect other apoptotic cells. Image 1 • A colorimetric assay designed for apoptosis in the cell-based and cell free systems. • Spontaneous biosynthesis of gold nanoparticles take place inside live cells and in the presence of cell lysates. • In-Situ synthesis of AuNPs by non-apoptotic and apoptotic cells. • Dominant role of redox state and aggregation of Cyt c in apoptotic cells in biosynthesis of AuNPs. [ABSTRACT FROM AUTHOR]