Biogenic Synthesis of Silver Nanoparticles with High Antimicrobial and Catalytic Activities using Sheng Di Huang (Rehmannia glutinosa).

Silver nanoparticles (AgNPs) are widely sought after for a variety of biomedical and environmental applications due to their antimicrobial and catalytic properties. We present here a green and simple synthesis of AgNPs utilizing traditional Chinese medicinal herbs. The screening of 20 aqueous herb extracts shows that Sheng Di Huang (Rehmannia glutinosa) had the most promising potential in producing AgNPs of 30±6 nm, with narrow size distribution and high crystallinity. The antimicrobial activities of these AgNPs conducted on E. coli cells were found to be superior in comparison to poly(vinylpyrrolidone)-capped AgNPs synthesized using common chemical method. Additionally, the AgNPs obtained possess excellent catalytic performance in the reduction of 4-nitrophenol to 4-aminophenol. We compared the phytochemical and FTIR spectral analyses of the herb extract before and after synthesis, in order to elucidate the phytochemicals responsible for the reduction of Ag+ ions and the capping of the AgNPs produced.

Single source precursor synthesized CuS nanoparticles for NIR phototherapy of cancer and photodegradation of organic carcinogen.

Herein, we report cost effective and body compatible CuS nanoparticles (NPs) derived from a single source precursor as photothermal agent for healing deep cancer and photocatalytic remediation of organic carcinogens. These NPs efficiently kill MCF7 cells (both in vivo and in vitro) under NIR irradiation by raising the temperature of tumor cells. Such materials can be used for the treatment of deep cancer as they can produce a heating effect using high wavelength and deeply penetrating NIR radiation. Furthermore, CuS NPs under solar light irradiation efficiently convert p-nitrophenol (PNP), an environmental carcinogen, to p-aminophenol (PAP) of pharmaceutical implication. In a nutshell, CuS can be used for the treatment of deep cancer and for the remediation of carcinogenic pollutants. There seems an intrinsic connection between the two functions of CuS NPs that need to be explored in length.

Biogenic synthesis of AgNPs employing Terminalia arjuna leaf extract and its efficacy towards catalytic degradation of organic dyes.

In the present work, we demonstrated the biosynthesis of silver nanoparticles (AgNPs) by highly stable, economic and eco-friendly method using leaf extract of Terminalia arjuna (T. arjuna) and employing as a catalyst for the degradation of methyl orange (MO), methylene blue (MB), congo red (CR) and 4- nitrophenol (4-NP). The biosynthesis of AgNPs was visually validated through the appearance of reddish-brown color and further confirmed by the UV-spectra at 418 nm. The TEM and FE-SEM studies revealed the spherical shape of particles with size ranged between 10-50 nm. Face centered cubic crystalline nature of AgNPs was proved by XRD analysis. The negative value of zeta potential (-21.7) indicated the stability of AgNPs and elemental composition was confirmed by EDS. FT-IR analysis revealed the functional groups present in the plant extract trigger the biosynthesis of AgNPs. The AgNPs exhibited strong degradation of MO (86.68%), MB (93.60%), CR (92.20%) and 4NP (88.80%) by completing the reduction reaction within 20 min. The reaction kinetics followed the pseudo-first-order and displayed k-values (rate constant) 0.166 min-1, 0.138 min-1, 0.182 min-1 and 0.142 min-1 for MO, MB, CR and 4-NP respectively. This study showed an efficient, feasible and reproducible method for the biosynthesis of eco-friendly, cheap and long-time stable AgNPs and their application as potent catalysts against the degradation of hazardous dyes.

Plant-mediated synthesis of dual-functional Eggshell/Ag nanocomposites towards catalysis and antibacterial applications.

Advances in nanotechnology provide plenty of exciting solutions to environmental issues affecting air, soil as well as water. To solve the water pollution problem caused by organics and microorganisms, development of a simple, environment-friendly, and cheap method for the synthesis of nanomaterials is of paramount importance. Herein, we prepared a novel nanocomposite (named Eggshell/Ag) using waste eggshell as a support and Cacumen platycladi extract as reducing and stabilizing agents in aqueous solutions at room temperature. Biogenic-stabilized Ag nanoparticles (Ag NPs) with an average diameter of 60 nm were well-dispersed on the surface of eggshells, exhibiting dual-functional properties of organics catalytic degradation and bacterial growth inhibition. Through five repeated assays, it was established that the reduction efficiency of the nanocomposite for 4-nitrophenol (4-NP) was high. The reduction could be completed rapidly at room temperature. Moreover, significant inhibition zones were observed for Staphylococcus aureus (S. aureus) agar plates and Escherichia coli (E. coli). Meanwhile, the minimum inhibition concentrations (MIC) were determined to be 0.08 and 0.04 mg mL-1, respectively, while the minimum bactericidal concentration (MBC) was measured as 0.64 mg mL-1. The biogenic Eggshell/Ag nanocomposites are promising candidates for a series of applications in the fields of biomedicine, environment as well as energy.

Strategy to improve gold nanoparticles loading efficiency on defect-free high silica ZSM-5 zeolite for the reduction of nitrophenols.

Catalytic reduction of toxic and aqueous stable nitrophenols by gold nanoparticles (Au NPs) is hot issue due to the serious environmental pollution in recent years. But the expensive price and poor recycling performance of Au NPs limit its further application. Defect-free high silica zeolite is suitable support for Au NPs due to its cheaper price, higher stability and stronger adsorbability, but the low alumina content and defect sites usually lead to poor Au NPs loading efficiency. Herein, we reported the improved Au NPs loading efficiency on defect-free high silica ZSM-5 zeolite through the additional surface fluffy structure. The fluffy structure was created through the addition of multi-walled carbon nanotubes (MWCNTs) and ethanol into synthesis gel. Highly dispersed ca. 4 nm Au NPs on zeolite surface are prepared by the green enhanced sol-gel immobilization method. The Au NPs loading efficiency on conventional ZSM-5 zeolite is 10.7%, in contrast, this result can arrive to 82.6% on fluffy structure ZSM-5 zeolite. The fluffy structure ZSM-5 zeolite and Au NPs nanocomposites show higher efficiency than traditional Au/ZSM-5 nanocomposites towards catalytic reduction of nitrophenols. Additionally, the experiments with different affecting factors (MWCNTs dosage, aging time, catalysts dosage, pH, initial 4-NP concentration, storage time and recycling times) were carried out to test general applicability of the nanocomposites. And the degradation of nitrophenols experiment was operated to explore the catalytic performance of the prepared nanocomposites in further environmental application. The detailed possible relationship between zeolite with fluffy structure and Au NPs is also proposed in the paper.

Synthesis of AgNPs coated with secondary metabolites of Acacia nilotica: An efficient antimicrobial and detoxification agent for environmental toxic organic pollutants.

This study concentrates on biosynthesis of Silver Nanoparticles (AgNPs) from stem extract of Acacia nilotica (A. nilotica). The reaction was completed at a temperature ~40-45 °C and time duration of 5 h. AgNPs were thoroughly investigated via advanced characterization techniques such as UV-Vis spectrophotometry (UV-Vis), Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffractometry (XRD), Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HRTEM), X-ray Photoelectron Spectroscopy (XPS), Thermo Gravimetric Analysis (TGA), Diffuse Reflectance Spectroscopy (DRS), Brunner-Emmett-Teller (BET), Dynamic Light Scattering (DLS), and Zeta potential analysis. AgNPs with average size below 50 nm were revealed by all the measuring techniques. Maximum surface area ~5.69 m2/g was reported for the as synthesized NPs with total pore volume ~0.0191 mL/g and average pore size ~1.13 nm. Physical properties such as size and shape have changed the surface plasmon resonance peak in UV-visible spectrum. Antimicrobial activity was reported due to denaturation of microbial ribosome's sulphur and phosphorus bond by silver ions against bacterium Methicillin Resistant Staphylococcus aureus (MRSA) and fungus Candida Albican (CA). Furthermore, AgNPs degraded toxic pollutants such as 4-nitrophenol (4-NP), 2-nitrophenol (2-NP) and various hazardous dyes such as Congo Red (CR), Methylene Blue (MB) and Methyl Orange (MO) up to 95%. The present work provided low cost, green and an effective way for synthesis of AgNPs which were utilized as potential antimicrobial agents as well as effective catalyst for detoxification of various pollutants and dyes.

Cellulose derived nitrogen and phosphorus co-doped carbon-based catalysts for catalytic reduction of p-nitrophenol.

The cellulose, which is one of the most abundant solid by-products of agriculture and forestry industry, has been successfully tested for the synthesis of nitrogen and phosphorus co-doped carbon-based metal-free catalysts (NPC) via freeze-drying the mixture of cellulose crystallite and ammonium phosphate, followed by annealing of the hydrogel under nitrogen atmosphere at 800 °C for 2 h. Different techniques including TEM, SEM, FTIR and XPS spectroscopy have been applied to characterize the as-prepared NPC, which presents flake-like morphology with N and P doping levels of 4.3 atom% and 10.66 atom%, respectively. The NPC exhibits excellent catalytic activity for the reduction of p-nitrophenol (p-NP). The turnover frequency (TOF) of the reduction of p-NP is as high as 2 × 10-5 mmol·mg-1·min-1 and the apparent kinetic rate constant was calculated as 0.0394 min-1 at room temperature. The catalytic mechanism is proposed by combining the density functional theory calculation and analysis of the experimental results. These findings open up new possibilities of valorization for cellulose-based by-product and treatment of p-NP-based wastewater.

One step preparation of stable gold nanoparticle using red cabbage extracts under UV light and its catalytic activity.

Herein, we have reported the synthesis, characterization and catalytic activity of highly stable gold nanoparticles (Au NPs) using red cabbage extract (RCE) under UV irradiation. The anthocyanin groups predominantly existing in RCE play an essential role for biosynthesis of stable Au NPs. The reasons for using anthocyanins: 1) they act as chelating agents for preferentially reacting with gold ions (Au3+) to form Au3+- anthocyanin complexes, 2) as light-active reductants for reduction of Au3+ to zero valent Au0 under UV irradiation and 3) as stabilizing agent for preventing Au NPs from aggregation in high salt concentration owing to their unique salt tolerance property. We also demonstrate that how reaction time, concentration of RCE, pH value of reaction solutions and using one more reducing agent affected formation of the Au NPs. The stability of RCE Au NPs was comparatively studied with commercial (citrate stabilized) Au NPs against 100 mM salt (NaCl) solution. The RCE-Au NP showed reduction ability for conversion of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). UV-vis spectrometry, transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta potential (ZT) methods were utilized to characterize the Au NPs. We demonstrated that how whole RCE (anthocyanins molecules are major component) can be used as photo-active reducing and stabilizing agents to form Au NPs in a short time under UV irradiation and strong reducing agent without additional agents.

Antimicrobial and catalytic activities of biosynthesized gold, silver and palladium nanoparticles from Solanum nigurum leaves.

The field of nanobiotechnology and nanomedicine paves way for the use of several nanoparticles. Especially, in biomedical applications, the silver nanoparticles (AgNPs), gold nanoparticles (AuNPs) and palladium nanoparticles (PdNPs) are found most vital and promising, among other nanoparticles. The biomedical activities of these particles mostly depend on their shape, size and distribution. Preparation of these particles in an eco-friendly method is an immediate need of the society. Herein, AuNPs, AgNPs and PdNPs (MNPS) were synthesized by Solanum nigrum Leaves (SNL) extract. The structural and morphological studies were carried out by using TEM, XRD and EDAX, while the optical and chemical properties were studied using UV-visible spectrum and FTIR spectroscopy. The particles obtained were found to possess a FCC (Face Centered Cubic) structure. TEM images of Ag, Au and PdNPs showed spherical well dispersed nanoparticles with average size of 3.46 nm, 9.39 nm and 21.55 nm respectively. The FTIR spectra confirmed polyphenols and antioxidants in SNL extract act as reducing and capping agents respectively in the synthesis of MNPs. The EDX technique confirmed the presence of silver, gold and palladium nanoparticles. Antimicrobial studies noted that the AgNPs have effective inhibition against E. coli. The complete reduction of 4-Nitrophenol and the formation of 4-Aminophenol with the presence of NaBH4 was chosen for the study of catalytic activities of the prepared MNPs. The reduction time of Au and Pd catalyst were smaller compared to that of Ag. This viable preparation method for producing small spherical shaped nanoparticles expected to the applied to the fields of nanomedicine.

Characterization of non-covalent immobilized Candida antartica lipase b over PS-b-P4VP as a model bio-reactive porous interface.

The design of interfaces that selectively react with molecules to transform them into compounds of industrial interest is an emerging area of research. An example of such reactions is the hydrolytic conversion of ester-based molecules to lipids and alcohols, which is of interest to the food, and pharmaceutical industries. In this study, a functional bio-interfaced layer was designed to hydrolyze 4-nitrophenyl acetate (pNPA) and Ricinus Communis (castor) oil rich in triglycerides using lipase b from Candida antarctica (CALB, EC 3.1.1.3). The attachment of CALB was performed via non-covalent immobilization over a polymer film of vertically aligned cylinders that resulted from the self-assembly of the di-block copolymer polystyrene-block-poly(4-vinyl pyridine) (PS-b-P4VP). This polymer-lipase model will serve as the groundwork for the design of further bioactive layers for separation applications requiring similar hydrolytic processes. Results from the fabricated functional bio-interfaced material include cylinders with featured pore size of 19 nm, d spacing of 34 nm, and ca. 40 nm of thickness. The polymer-enzyme layers were physically characterized using AFM, XPS, and FTIR. The immobilized enzyme was able to retain 91% of the initial enzymatic activity when using 4-nitrophenyl acetate (pNPA) and 78% when exposed to triglycerides from castor oil.

Phytosynthesis of Cu/rGO using Euphorbia cheiradenia Boiss extract and study of its ability in the reduction of organic dyes and 4-nitrophenol in aqueous medium.

For the first time, copper nanoparticles (Cu NPs) superficially deposited on reduced graphene oxide (rGO) using Euphorbia cheiradenia Boiss leaf aqueous media. A beneficial series of analytical methods was used to characterise E. cheiradenia Boiss leaf extract and involved nanostructures. The Cu/rGO nanocomposite (NC) obtained from the conversion of Cu2+ ions to Cu NPs and GO to rGO undergoes the plant extract and used as a heterogeneous and reusable nanocatalyst for the destruction of 4-nitrophenol, rhodamine B, methylene blue, methyl orange and congo red using sodium borohydride at ambient temperature. In addition, Cu/rGO NC has reusability for many times in the reduction reactions with no decreasing of its catalytic capability.

Nanozyme-assisted technique for dual mode detection of organophosphorus pesticide.

A novel dual-mode analytical method by employing nanozyme was developed for the detection of organophosphorus pesticides (OPP) for the first time. The detection principle is that the pesticide could be hydrolyzed to para-nitrophenol (p-NP) in the presence of nanoceria as nanozyme. p-NP exhibits the bright yellow color, and its color intensity has a positive correlation with the pesticide concentration. Meanwhile, the characteristic absorption peak at 400 nm of p-NP increases gradually with the raised concentration of pesticide. Therefore, a dual-mode method including smartphone-based colorimetric and spectroscopic strategies was rationally developed. Herein, methyl-paraoxon was selected as the representative compound. Under the optimum conditions, the detection limits of both two strategies were calculated to be 0.42 µmol L-1. Finally, the present method was successfully applied in three edible medicinal plants (Semen nelumbinis, Semen Armeniacae Amarum, Rhizoma Dioscoreae). The present work offers a reliable and convenient approach for routine detection of pesticide based on two different detection mechanisms.

Euphorbia leaf extract-assisted sustainable synthesis of Au NPs supported on exfoliated GO for superior activity on water purification: reduction of 4-NP and MB.

In the present work, the effect of graphene oxide (GO) architecture and synthesis of gold nanoparticles (AuNPs) on the surface of GO by using Euphorbia leaf extract was investigated. The as-synthesized catalyst was utilized for reduction of 4-nitrophenol (4-NP) and methylene-blue (MB). The ethanol/water extract of the leaves of Euphorbia was found as a non-toxic, suitable, eco-friendly natural reducing agent in one-step generation of Au nanoparticles onto the GO. The catalyst was characterized by different analysis such as atomic force microscopy, powder X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, SEM-mapping, transmission electron microscopy, and atomic absorption spectrometry. The high catalytic performance of the surfactant exfoliated gold-GO (SE-AuNPs/GO) towards the reduction of 4-NP to 4-aminophenol (4-AP) and reduction of MB to leucomethylene blue (LMB) under mild conditions, in water and at room temperature, was exhibited. Graphical abstract.

Silver and gold nanoparticles biosynthesized by aqueous extract of burdock root, Arctium lappa as antimicrobial agent and catalyst for degradation of pollutants.

This study presents an efficient and facile method for biosynthesis of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using aqueous extract of burdock root (BR), A. lappa, and their applications. The nanoparticles were characterized by ultraviolet-visible spectrophotometry, X-ray diffraction, transmission electron microscopy, energy dispersive X-ray, thermogravimetry, and differential thermal analysis. AgNPs capped the BR extract (BR-AgNPs) possessed roughly spherical geometry with an average diameter of 21.3 nm while uneven geometry of AuNPs capped the BR extract (BR-AuNPs) showed multi shapes in average size of 24.7 nm. The BR-AgNPs strongly inhibited five tested microorganism strains. In particular, the nanoparticles showed excellent catalytic activity for the conversion of pollutants within wastewater. Pseudo-first-order rate constants for the degradation of 4-nitrophenol, methyl orange, and rhodamine B were respectively found 6.77 × 10-3, 3.70 × 10-3, and 6.07 × 10-3 s-1 for BR-AgNPs and 6.87 × 10-3, 6.07 × 10-3, and 7.07 × 10-3 s-1 for BR-AuNPs. Graphical abstract ᅟ.

Green synthesis of silver and gold nanoparticles using Stemona tuberosa Lour and screening for their catalytic activity in the degradation of toxic chemicals.

In the present study, silver and gold nanoparticles (AgNPs and AuNPs) were green synthesised using the aqueous plant extract of Stemona tuberosa Lour. When plant extract was mixed with AgNO3 and HAuCl4 solutions in separate reactions, the amalgamated solutions turned deep reddish brown and dark purple in colour after 48 h indicating the formation of AgNPs and AuNPs. UV-Visible analysis of green synthesised AgNPs and AuNPs have shown absorption maximum at 443.85 nm and 539.72 respectively after 48 h. Energy dispersive X-ray spectroscopy (EDX) analysis confirmed the presence of pure silver in the green synthesised AgNPs and pure gold in the plant-mediated AuNPs. X-ray diffractometer (XRD) data revealed the face-centred cubic nature of AgNPs. Fluorescence transmission infrared (FTIR) spectrum has shown the characteristic peaks of different phytochemicals in the plant extract which acted as stabilising or capping agents of AgNPs. Scanning electron microscopy (SEM) analysis of AgNPs and AuNPs revealed that the nanoparticles are monodispersed. Transmission electron microscopy (TEM) studies revealed that AgNPs were mostly spherical with an average size of 25 nm whereas selected area electron diffraction (SAED) analysis confirmed their crystalline nature. Both AgNPs and AuNPs of S. tuberosa Lour have shown potential catalytic activity in the presence of sodium borohydride (NaBH4) in the degradation and removal of 4-nitrophenol, methylene blue, methyl orange and methyl red.

Biosynthesis of waste pistachio shell supported silver nanoparticles for the catalytic reduction processes.

Silver nanoparticles (NPs) are immobilised on pistachio shell surface by Cichorium intybus L. leaves extract as an antioxidant media. The Fourier transform infrared spectra, X-ray diffraction, field-emission scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy, and transmission electron microscope analyses confirmed the support of silver NPs on the pistachio shell (Ag NPs/pistachio shell). Ag NPs on the pistachio shell had a diameter basically in the 10-15 nm range. Reduction reactions of 4-nitrophenol (4-NP), and organic dyes at ambient condition were used in the investigation of the catalytic performance of the prepared catalyst. Through this research, the Ag NPs/pistachio shell shows a high activity and recyclability, and reusability without loss of its catalytic activity.

Green synthesis of gold nanoparticles using Artemisia dracunculus extract: control of the shape and size by varying synthesis conditions.

In this study, selective green synthesis of gold nanoparticles (nAu) with the use of Tarragon extract (Artemisia dracunculus) was investigated. Characterization of the synthetized nAu was carried out using several techniques including: UV-Vis, SEM, zeta potential analysis, DLS, and ATR-FTIR. Based on measurements of Tarragon extract by HPLC-MS, significant chemical substances participating as reducing and stabilizing agents were identified. FTIR confirmed typical functional groups that could be found in these acids on the nAu surface, such as O-H, C=O and C-O. The effects of various parameters (concentration of Tarragon extract, Au precursor, and initial pH of the synthesis) on the shape and size of the nanoparticles have been investigated. UV-Vis and SEM confirmed the formation of nAu at various concentrations of the extract and Au precursor and showed correlation between the added extract concentration and shift in maximal absorbance towards higher frequencies, indicating the formation of smaller nanoplates. Zeta potential determined at various pH levels revealed that its value decreased with pH, but for all experiments in the pH range of 2.8 to 5.0, the value is below - 30 mV, an absolute value high enough for long-term nAu stability. In order to evaluate nAu catalytic activity, the reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride was used as a model system. The reaction takes place 1.5 times faster on Au-triangles than on Au-spherical NPs.

In situ green synthesis of Ag nanoparticles on herbal tea extract (Stachys lavandulifolia)-modified magnetic iron oxide nanoparticles as antibacterial agent and their 4-nitrophenol catalytic reduction activity.

For first time, we designed an environment friendly technique novel hybrid magnetic nanocomposite with the potency of both reducing and stabilizing agent for immobilization of metal nanoparticles. Stachys lavandulifolia extract having a lot of carbonyl and phenolic hydroxyl functional groups can be applied in the Fe3O4 NPs modification. Furthermore, in aqueous solution, the complexation feasibility of polyphenols with silver ions can enhance the capacity and surface properties of the Fe3O4@S. lavandulifolia NPs for sorbent and in situ reduction of silver ions. So, as both the stabilizing and reducing agent, the novel magnetic nano-sorbent (Fe3O4@S. lavandulifolia NPs) has potential ability for silver nano particles immobilization to create a novel magnetic silver nanocatalyst. So that, no additional reductants, toxic reagents and intricate instruments are needed to prepare the catalyst. The morphology, structure, and physicochemical properties were elucidated by several analytical methods like, field emission scanning electron microscope (FESEM), high resolution transmission electron microscopy (HRTEM) images, energy-dispersive X-ray spectroscopy (EDS), vibrating sample magnetometer (VSM), X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy, and inductively coupled plasma (ICP). As recyclable nanocatalyst, Fe3O4@S. lavandulifolia/Ag indicated high catalytic activity for 4-nitrophenol (4-NP) reduction at ambient temperature. Ultimately, the Fe3O4@S. lavandulifolia/Ag antibacterial properties was examined against two bacteria (Staphylococcus aureus (Staph. aureus) and Escherichia coli (E. coli)) and indicated its antibacterial activities against gram negative (E. coli) bacteria and gram positive (Staph. aureus).

Biogenic gold nanoparticles for reduction of 4-nitrophenol to 4-aminophenol: an eco-friendly bioremediation.

The present study investigated the synthesis of gold nanoparticles (AuNPs) using mangrove plant extract from Avicennia marina as bioreductant for eco-friendly bioremediation of 4-nitrophenol (4-NP). The AuNPs synthesised were confirmed by UV spectrum, transmission electron microscopy (TEM), X-ray diffraction, Fourier transmission infrared spectroscopy (FTIR), dynamic light scattering (DLS), and zeta potential. The AuNPs were found to be spherical in shape with size ranging from 4 to 13 nm, as evident by TEM and DLS. Further, the AuNPs were encapsulated with sodium alginate in the form of gold nano beads and used as heterogeneous catalyst and degrading agent to reduce 4-NP. This reduction in 4-NP into 4-aminophenol was confirmed by UV and FTIR. The aqueous solution of 4-NP peaked its absorbance at 320 nm, and shifted to 400 nm, with an intense yellow colour, appeared due to formation of 4-nitrophenolate ion. After the addition of AuNps, the 4-NP solution became colourless and peaked at 400 nm and reduced to 290 nm corresponding to the formation of 4-aminophenol. Hence, the present work suggested the AuNPs as the potent, eco-friendly bionanocomposite catalyst for bioremediation of 4-NP.

Albizia chevalier based Ag nanoparticles: Anti-proliferation, bactericidal and pollutants degradation performance.

The eco-friendly biosynthesis of silver nanoparticles (AgNps) from bark extract of Albizia chevalier are reported here for their anti-proliferative, antibacterial and pollutant degradation potentials. The synthesized AgNps were characterized by FTIR spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy dispersive X-rays spectrometry (EDS) and X-ray diffraction studies. The TEM and FESEM images show a monodispersed spherical shaped particles of approximately 30 nm. Crystalline peaks were obtained for the synthesized AgNps in XRD spectrum. The AgNps were investigated for in vitro anticancer and antibacterial activities and its potential to degrade 4-nitrophenol (4-NP) and congo red dye (CR). The MTT results shows a significant dose-dependent antiproliferation effect of the AgNps on the cell lines HepG2, MDA-MB-231 and MFC7. The effect was found more pronounced in MDA-MB-231 as compared to MFC-7 cell lines. The antibacterial results indicated 99 and 95% killing of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) respectively, after 24 h of incubation with the AgNps. The AgNps were found to speed up the reductive degradation of 4-NP and CR dye, which give an alternative route for the removal of toxic organic pollutants from the wastewater. The synthesized AgNps were not only used as a bactericidal and anticancer agent, but also effectively used for the reductive degradation of carcinogenic compounds which are listed as the priority pollutants. Therefore, AgNps have the potential for the treatment of various cancers, bacterial infections and for industrial detoxification of wastewater.