The current study is focussed on bio-fabrication of single step Durenta erecta (D. erecta ) fruit extract synthesis of silver nanoparticles (Ag NPs). The prepared materials were examined through UV–Vis spectrophotometry due to localized surface plasmon resonance (SPR) and were found highly stable. X-ray diffraction (XRD) revealed face centered cubic (fcc) crystalline nature of Ag NPs. Morphologies and average size of Ag NPs was evaluated by field emission-scanning electron microscopy (FE-SEM), while elemental analysis was carried out by energy dispersive X-rays spectroscopy (EDS) and X-ray photo electron spectroscopy (XPS). Fourier transform infrared spectroscopy (FTIR) displayed the presence of the functional groups responsible for reducing as well as stabilizing of Ag NPs. The prepared Ag NPs were applied as colorimetric optical sensors for the detection of carcinogenic hexavalent chromium (Cr 6+) and ammonia and the kinetic shift in λmax and change in color for both Cr6+ and ammonia was found to be extremely fast and took a few seconds. Characteristic SPR, low-cost, high sensitivity, simplicity, lower detection limit up to 0.1 ppm and fast response time of Ag NPs are very useful for the colorimetric detection of Cr 6+ and ammonia and can be used as an optical sensor for clinical diagnosis at room temperature.

Biosynthesis of silver nanoparticles: A colorimetric optical sensor for detection of hexavalent chromium and ammonia in aqueous solution

Silver nanoparticles (Ag. NPs) have shown a biological activity range, synthesized under different environment-friendly approaches. Ag. NPs were synthesized using aqueous crude extract (ACE) isolated from Plantago lanceolata. The ACE and Ag. NPs were characterized and assessed their biological and antioxidant activities. The existence of nanoparticles (NPs) was confirmed by color shift, atomic force microscopy (AFM), and UV–Vis’s spectroscopy. The FT-IR analysis indicated the association of biomolecules (phenolic acid and flavonoids) to reduce silver (Ag+) ions. The SEM study demonstrated a sphere-shaped and mean size in the range of 30 ± 4 nm. The EDX spectrum revealed that the Ag. NPs were composed of 54.87% Ag with 20 nm size as identified by SEM and TEM. AFM has ended up being exceptionally useful in deciding morphological elements and the distance across of Ag. NPs in the scope of 23–30 nm. The TEM image showed aggregations of NPs and physical interaction. Ag. NPs formation also confirmed by XPS, DRS and BET studies. Ag. NPs showed efficient activity as compared to ACE, and finally, the bacterial growth was impaired by biogenic NPs. The lethal dose (LD50) of Ag. NPs against Agrobacterium tumefaciens, Proteus vulgaris, Staphylococcus aureus, and Escherichia coli were 45.66%, 139.71%, 332.87%, and 45.54%, with IC50 (08.02 ± 0.68), (55.78 ± 1.01), (12.34 ± 1.35) and (11.68 ± 1.42) respectively, suppressing the growth as compared to ACE. The antioxidant capacity, i.e., 2,2-diphenyl-1-picrylhydrazyl (DPPH) of Ag. NPs were assayed. ACE and Ag. NPs achieved a peak antioxidant capacity of 62.43 ± 2.4 and 16.85 ± 0.4 μg mL−1, compared to standard (69.60 ± 1.1 at 100 μg mL−1) with IC50 (369.5 ± 13.42 and 159.5 ± 10.52 respectively). Finally, the Ag. NPs synthesized by P. lanceolata extract have an excellent source of bioactive natural products (NP). Outstanding antioxidant, antibacterial activities have been shown by NPs and can be used in various biological techniques in future research.

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Synthesis of silver nanoparticles using Plantago lanceolata extract and assessing their antibacterial and antioxidant activities.

Herein, new Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) complexes incorporating 4-{[(2-hydroxyphenyl)imino]methyl}phenyl 4-methylbenzenesulfonate Schiff-base ligand (HL) were designed, synthesized, and characterized. The structure of the new compounds was elucidated based on spectroscopic techniques (nuclear magnetic resonance [NMR], ultraviolet–visible [UV-vis], infrared [IR], mass), magnetic, conductivity, thermal analysis (thermogravimetric analysis [TGA], differential thermal analysis [DTA]) measurements, in addition to complex stoichiometry determination using molar ratio and Job's methods. The new complexes showed an interesting structural variation: square-planar (in the case of NiL), tetrahedral (in the case of CuL), and octahedral (in the case of FeL2, CoL2, and ZnL2). Furthermore, density functional theory (DFT) calculations were performed to obtain deep insights into the structural features, orbital interactions, and electronic chemical descriptors evaluation. Moreover, the anti-inflammatory behavior of the titled compounds was in vitro investigated. Interestingly, the ZnL2 complex showed the highest activity, whereas the CuL complex showed the lowest activity compared with the other compounds. In order to ascertain the bioactivity of the present compounds, their efficacy was compared with previously reported compounds showing high activity. The anti-inflammatory activity was supported by molecular docking analysis against cyclooxygenase-2 (COX-2) enzyme (PDB ID: 5IKT), which confirms the bioactivity behavior. The obtained results indicated that the titled compounds could be promising anti-inflammatory candidates. 

New mononuclear Fe (III), Co (II), Ni (II), Cu (II), and Zn (II) complexes incorporating 4‐{[(2 hydroxyphenyl)imino]methyl}phenyl‐4‐methylbenzenesulfonate (HL): Synthesis, characterization, theoretical, anti‐inflammatory and molecular docking investigation

Plant-based synthesis of Ag-doped ZnO/MgO nanocomposites using Caccinia macranthera extract and evaluation of their photocatalytic activity, cytotoxicity, and potential application as a novel sensor for detection of Pb2+ ions

In this study, decorated silver nanoparticles on two dimensional (2D) -biphenol-biphenoquinone nanoribbons (AgNPs-BP-BPQ NRs) were prepared for the first time by a novel, fast and simple method. The mentioned compound was then used as modifier for preparation of modified graphite paste electrode (GPE/AgNPs-BP-BPQ NRs) for indirect voltammetric determination of carcinogen hexavalent chromium (Cr (VI). Peak current of BP/BPQ redox system was decreased in the presence of Cr (VI), hence, this decrease in peak current was used as the electroanalytical signal for quantitative determination of Cr (VI). Moreover, the redox reaction of Cr (VI) and BP was investigated in this study for the first time and the product was characterized. Different techniques such as field emission electron microscopy, Energy-dispersive X-ray spectroscopy, transmission electron microscopy, atomic force microscopy and fourier transform infrared spectroscopy were performed for characterization of the AgNPs-BP-BPQ NRs. Different electrochemical methods, such as cyclic voltammetry, electrochemical impedance spectroscopy and differential pulse voltammetry, were employed to study the behavior of Cr (VI) on the proposed modified electrode. Under the optimum conditions, the calibration curve was liner in the ranges of 8.0 × 10−11 to 1.0 × 10-8, 1.0 × 10-8 to 1.0 × 10-6 and 1.0 × 10-6 to 1.0 × 10-4 M with a detection limit of 2.0 × 10-12 M. Finally, this sensor was successfully used for determination of Cr (VI) in tap water, river water and electroplating waste water samples.

Ultra-trace determination of hexavalent chromium by novel two dimensional biphenol-biphenoquinone nanoribbons/silver nanoparticles

Silver nano-colloid was rapidly synthesized by treating silver ions with a blend of extracts from two leaves (Ocimum sanctum and Azadirachta indica). The reaction method was simple, eco-friendly and was monitored using UV–Vis spectroscopy. The effect of leaf extract on the formation of silver nano-colloid was studied using FTIR spectroscopy. The morphology of the synthesized colloid was stable with spherical particles of a 10-nm size. The results indicate that leaf extract acts as a reducing and stabilizing agent. The synthesized Ag nano-colloid exhibited a good colorimetric sensing property towards carcinogenic Cr(VI) anions [(Cr2O7)2−] in aqueous solution by changing the colour of the solution from “brown to red” accompanied with an increase in absorption intensity. The proposed detection method of the sensor has been discussed. The detection limit of the sensor was found to be 10−6 M. There was no interference observed for Cr(VI) anion detection in the presence of other cations and anions. The proposed sensor can be applied for the detection of Cr(VI) anion in drinking water samples. The antidiabetic ability of silver colloid was tested and the results showed inhibition of carbohydrate digestive enzymes. Thus, the current study focuses on a highly specific and selective liquid colorimetric sensor for (Cr2O7)2− anions. The silver nano-particles (Ag NPs) derived from a blend of neem (Azadirachta indica) and tulsi (Ocimum sanctum) leaves displayed an enhanced inhibitory effect towards a α-glucosidase and α-amylase enzyme model, compared to their respective crude extracts and the control. As a result, the bioderived Ag NPs can be used as new nano-therapy for the treatment of diabetes.

Biogenic synthesized silver colloid for colorimetric sensing of dichromate ion and antidiabetic studies

Green synthesis of Phenothiazinium Schiff base and its nano silver complex using egg white as a catalyst under solvent free condition

In the current work, silver nanoparticles (AgNPs) were green synthesized using starch and modified with anionic dye (acid fuchsin) and aldehyde (salicylaldehyde and cinnamaldehyde). Thus in situ formation of Schiff base stabilized AgNPs were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis. The size and the stability of the Schiff base modified AgNPs were explored using DLS and Zeta potential analysis. TEM analyses showed the size of the Schiff base (cinnamaldehyde) modified AgNPs with an average particle size of 5–10 nm. The synthesized Schiff base modified AgNPs were tested for their antibacterial efficacy against gram-negative bacteria such as Escherichia coli (MTCC733), Pseudomonas aeruginosa (MTCC1688) and gram-positive bacteria such as Bacillus subtilis (MTCC41) and Enterococcus faecalis (MTCC96). The antifungal activity of the synthesized materials has been studied against Candida albicans along with standard fluconazole. Higher antibacterial and antifungal activities were observed for the Schiff base (SB) capped AgNPs due to the combined effect of SB and AgNPs. The mechanism of the bactericidal activity of nanoparticles is suggested as due to the interaction of AgNPs with the cell membrane. The results of the present study confirm that SB stabilized AgNPs have significant potential as an antimicrobial agent in treating infectious diseases.

Synthesis, Characterisation, and Antimicrobial Efficacy of Acid Fuchsin Schiff Base-Modified Silver Nanoparticles

Wound infection is a major clinical challenge, impacting patient morbidity and mortality, with significant economic implications. Our research focused on how Pisonia Alba (PA) leaves, which are used to treat wounds, are used to synthesize silver nanoparticles and study their wound healing property. UV-visible spectroscopy, X-ray diffraction analysis, and s electron microscope (SEM) analysis were employed to evaluate the synthesized silver nanoparticles. Using DLS and Zeta potential analysis, the size and stability of the Pisonia Alba capped silver nanoparticle were investigated. The results showed that Pisonia Alba extract stabilized silver nanoparticles are 63.88 nm in size and have a spherical shape. Antibacterial and antibiofilm potential of synthesized silver nanoparticles against pathogenic organisms Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria were investigated. The in vitro cell scratch wounding assay is used to investigate the wound healing properties of synthesized nanoparticles. Pisonia Alba stabilized silver nanoparticles (PA@AgNPs), in comparison to Pisonia Alba (PA) extract, show effective wound healing characteristics by inducing the formation of collagen and serving as a capable wound healing agent.

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Suba Kannaiyan

Papers

Biogenic synthesized silver colloid for colorimetric sensing of dichromate ion and antidiabetic studies

Green synthesis of Phenothiazinium Schiff base and its nano silver complex using egg white as a catalyst under solvent free condition

Synthesis, Characterisation, and Antimicrobial Efficacy of Acid Fuchsin Schiff Base-Modified Silver Nanoparticles

Pisonia Alba Assisted Synthesis of Nanosilver for Wound Healing Activity