Chuanlong Li

Green biosynthesis of silver nanoparticles using leaves extract of Artemisia vulgaris and their potential biomedical applications

Biosynthesis of nanoparticles from plant extracts is receiving enormous interest due to their abundant availability and a broad spectrum of bioactive reducing metabolites. In this study, the reducing potential of Artemisia vulgaris leaves extract (AVLE) was investigated for synthesizing silver nanoparticles without the addition of any external reducing or capping agent. The appearance of blackish brown color evidenced the complete synthesis of nanoparticles. The synthesized silver nanoparticles were characterized by UV-vis spectroscopy, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), atomic force microscopy (AFM) and Fourier transforms infrared spectroscopy (FT-IR) analysis. UV-vis absorption profile of the bio-reduced sample elucidated the main peak around 420nm, which correspond to the surface plasmon resonance of silver nanoparticles. SEM and AFM analyses confirmed the morphology of the synthesized nanoparticles. Similarly, particles with a distinctive peak of silver were examined with EDX. The average diameter of silver nanoparticles was about 25nm from Transmission Electron Microscopy (TEM). FTIR spectroscopy scrutinized the involvement of various functional groups during nanoparticle synthesis. The green synthesized nanoparticles presented effective antibacterial activity against pathogenic bacteria than AVLE alone. In-vitro antioxidant assays revealed that silver nanoparticles (AV-AgNPs) exhibited promising antioxidant properties. The nanoparticles also displayed a potent cytotoxic effect against HeLa and MCF-7 cell lines. In conclusion, the results supported the advantages of employing a bio-green approach for developing silver nanoparticles with antimicrobial, antioxidant, and antiproliferative activities in a simple and cost- competitive manner.

Fluorescent sensor based models for the detection of environmentally-related toxic heavy metals

The quest for industrial and biotechnological revolution has been contributed in increasing environmental contamination issues, worldwide. The controlled or uncontrolled release of hazardous pollutants from various industrial sectors is one of the key problems facing humanity. Among them, adverse influences of lead, cadmium, and mercury on human health are well known to cause many disorders like reproductive, neurological, endocrine system, and cardiovascular, etc. Besides their presence at lower concentrations, most of these toxic heavy metals are posing noteworthy toxicological concerns. In this context, notable efforts from various regulatory authorities, the increase in the concentration of these toxic heavy metals in the environment is of serious concern, so real-time monitoring is urgently required. This necessitates the exploration for novel and efficient probes for recognition of these toxic agents. Among various methodologies adopted for tailoring such probes, generally the methodologies, in which changes associated with spectral properties, are preferred for the deceptive ease in the recognition process. Accordingly, a promising modality has emerged in the form of radiometric and colorimetric monitoring of these toxic agents. Herein, we review fluorescent sensor based models and their potentialities to address the detection fate of hazardous pollutants for a cleaner environment. Second, recent advances regarding small molecule and rhodamine-based fluorescent sensors, radiometric and colorimetric probes are discussed. The information is also given on the photoinduced electron transfer (PET) mechanism, chelation enhancement fluorescence (CHEF) effect and spirocyclic ring opening mechanism.

Polymer Vesicle Sensor for Visual and Sensitive Detection of SO2 in Water

This study reports the first polymer vesicle sensor for the visual detection of SO2 and its derivatives in water. A strong binding ability between tertiary alkanolamines and SO2 has been used as the driving force for the detection by the graft of tertiary amine alcohol (TAA) groups onto an amphiphilic hyperbranched multiarm polymer, which can self-assemble into vesicles with enriched TAA groups on the surface. The polymer vesicles will undergo proton exchange with cresol red (CR) to produce CR-immobilized vesicles (CR@vesicles). Subsequently, through competitive binding with the TAA groups between CR and SO2 or HSO3-, the CR@vesicles (purple) can quickly change into SO2@vesicles (colorless) with the release of protonated CR (yellow). Such a fast purple to yellow transition in the solution allows the visual detection of SO2 or its derivatives in water by the naked eye. A visual test paper for SO2 gas has also been demonstrated by the adsorption of CR@vesicles onto paper. Meanwhile, the detection limit of CR@vesicles for HSO3- is approximately 25 nM, which is improved by approximately 30 times when compared with that of small molecule-based sensors with a similar structure (0.83 μM). Such an enhanced detection sensitivity should be related to the enrichment of TAA groups as well as the CR in CR@vesicles. In addition, the CR@vesicle sensors also show selectivity and specificity for the detection of SO2 or HSO3- among anions such as F-, Br-, Cl-, SO42-, NO2-, C2O42-, S2O32-, SCN-, AcO-, SO32-, S2-, and HCO3-.

Development of silver nanoparticles loaded chitosan-alginate constructs with biomedical potentialities

Herein, a facile biosynthesis of silver nanoparticles (AgNPs) and AgNPs-loaded chitosan-alginate constructs with biomedical potentialities is reported. The UV-vis spectroscopic profile confirmed the synthesis of AgNPs using methanolic leaves extract of Euphorbia helioscopia. The newly developed AgNPs were characterized using various analytical and imaging techniques including UV-vis and FT-IR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The optimally yielded AgNPs at 24h reaction period were loaded onto various chitosan-alginate constructs. A maximum of 95% loading efficiency (LE) was recorded with a chitosan: alginate ratio at 2:1, followed by 81% at 2:2 ratios. The anti-bacterial activities of AgNPs and AgNPs loaded chitosan-alginate constructs were tested against six bacterial strains i.e. Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii, Morganella morganii and Haemophilus influenza. A significant reduction in the log values was recorded for all test constructs, in comparison to the initial bacterial count (control value, i.e., 1.5×108 CFU/mL). The cytotoxicity profile revealed complete biocompatibility against normal cell line i.e. L929. Almost all constructs showed considerable cytotoxicity up to certain extant against human epithelial cells (HeLa) cancer cells. In summary, the highest antibacterial activities along with anti-cancer behavior both suggest the biomedical potentialities of newly engineered AgNPs and AgNPs-loaded chitosan-alginate constructs.

Catalytic potential of bio-synthesized silver nanoparticles using Convolvulus arvensis extract for the degradation of environmental pollutants

Herein, we reported a facile, green and environmental friendlier biosynthesis of silver nanoparticles using the Convolvulus arvensis extract. The influences of various physicochemical factors such as the concentration of the plant extract, reaction time, and different pH levels were investigated by UV-Vis spectroscopy. The UV-Visible absorption spectrum of biogenic silver nanoparticles at λmax around ~400u202fnm suggested the biosynthesis of silver nanoparticles. Fourier transform infrared spectroscopy was employed to confirm the chemical transformation and role of various phyto-reductants in the conversion of Ag+ to Ag0. The surface morphology, topography, and elemental composition were analyzed by scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy, respectively. X-ray diffraction corroborated the face-centered cubic crystalline structure. The dynamic light scattering and zeta potential demonstrate the size distribution (90.9u202fnm) and surface charge (-18.5). Finally, the newly developed C. arvensis based silver nanoparticles were exploited as a catalyst for the catalytic reduction of azo dyes in the presence of NaBH4 as a reducing agent, and reducing the activity of C. arvensis based silver nanoparticles was evaluated by a decrease in optical density using UV-Vis spectrophotometer. The nanoparticles developed herein displayed potential efficiency for the degradation of all the tested dye pollutants. Conclusively, plant-based synthesis of nanoparticles provides an environmentally-responsive option for the reduction of highly environmental-polluted organic compounds including toxic azo dyes as compared to chemical and physical methods.

Potentially toxic elements and environmentally-related pollutants recognition using colorimetric and ratiometric fluorescent probes

A safer detection or sensing of toxic pollutants is one among several environmental contamination issues, across the globe. The ever-increasing industrial practices and controlled or uncontrolled release of toxic pollutants from various industrial sectors is a key source of this environmental problem. Significant research efforts have been or being made to tackle this problematic issue to fulfill the growing needs of the modern world. Despite many useful aspects, heavy metals are posing noteworthy toxicological concerns and human-health related issues at various levels of the ecosystem. In this context, notable efforts from various regulatory authorities, the increase in the concentration of these toxic heavy metals in the environment is of serious concern, so real-time monitoring is urgently required. Herein, we reviewed fluorescent sensor based models and their potentialities to address the detection fate of hazardous pollutants including chromium, manganese, cobalt, nickel, copper, and zinc as model elements. The novel aspects of turn-on/off fluorescent sensors have also been discussed from a state of the art viewpoint. In summary, comprehensive literature regarding fluorescent sensor based models and their potentialities to detect various types of toxic pollutants is reviewed.

Biomedical Potentialities of Taraxacum officinale-based Nanoparticles Biosynthesized Using Methanolic Leaf Extract

BACKGROUNDnIn the present study, the potential of methanolic leaf extract of Taraxacum officinale plant as a function of bio-inspired green synthesis for the fabrication of silver nanoparticles (AgNPs) has been explored.nnnMETHODSnThe bio-reduction of aqueous silver nitrate (AgNO3) solution was confirmed by visually detecting the color change from pale yellow to blackish-brown. Maximum absorbance was observed at 420 nm due to the presence of characteristic surface Plasmon resonance of nano silver by UV-visible spectroscopy. The role of various functional groups in the bio-reduction of silver and chemical transformation was verified by Fourier transform infrared spectroscopy (FTIR). Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) predict the shape (rocky, flack type, ellipsoidal, etc.), size (68 nm) and elemental composition (Ag as a major constituent) of the biosynthesized AgNPs, respectively.nnnRESULTSnTransmission electron microscopy (TEM) analysis further corroborated the morphology of the AgNPs. Color mapping and atomic force microscopy (AFM) confirmed the nano-sized topography. The dynamic light scattering (DLS) showed the charge, stability, and size of the AgNPs. The generated AgNPs presented potential antibacterial activities against Gram-positive and Gram-negative bacterial strains including Staphylococcus aureus, Escherichia coli, and Haemophilus influenzae. The biosynthesized AgNPs also showed antiproliferative activity against MCF-7 breast cancer cell line in a dosedependent manner.nnnCONCLUSIONnIn conclusion, results clearly indicate that biosynthesized AgNPs could be used as effective nano drug for treating infectious diseases caused by multidrug resistant bacterial strains in the near future.

Self-assembly and functionalization of alternating copolymer vesicles

This work reports on the preparation and functionalization of novel alternating copolymer vesicles. An amphiphilic alternating copolymer was synthesized first by the epoxy-thiol click reaction of 1,7-octadienediepoxide and 1,4-dithiothreitol. Then its self-assembly in selective solvents was studied through a simple injection method. The size and morphology of the self-assemblies were investigated by dynamic light scattering (DLS) and transmission electron microscope (TEM), scanning electron microscope (SEM), atomic force microscope (AFM) and cryogenic transmission electron microscope (cryo-TEM) measurements. The results showed that the abovementioned alternating copolymers could self-assemble into vesicles with a monolayer structure. Then a modular click reaction was employed to functionalize the obtained vesicles. Two kinds of functional groups, including the carboxyl group and the amino group, were successively introduced into the vesicles through the facile click-copolymerization of the alternating copolymers, indicating that the modular click reaction is quite potent in functionalizing these vesicles. The combined advantages of facile synthesis, self-assembly and functionalization offer a promising perspective for the application of such alternating copolymer vesicles.

Bio-Inspired Supramolecular Membranes: A Pathway to Separation and Purification of Emerging Pollutants

Supramolecular membranes based separation and/or purification is an emerging technology with tunable capabilities for several applications. The proposed applications include water desalination, wastewater treatment, and separation and purification of emerging pollutants alleviating the global issue of freshwater scarcity. Advanced water purification and separation methods are required on priority to meet the demand of a growing world population. Owing to their unique physiochemical and structural properties in combination with reversible and highly selective nature, supramolecular materials are gaining research interests to engineer multifunctional separation membranes. These materials give excellent properties to the separating membranes when used with commercial crosslinked polyamide network membranes and are cost-effective from the operational viewpoint. Herein, an effort has been made to review several types of supramolecular biomimetic membranes that include pressure-driven membranes, bio-inspired supramolecular water channels, aquaporin, advanced planar aquaporin, vesicular aquaporin-based biomimetic membranes, and catecholamine-based supramolecular membranes. Several nanopore-sized materials are being developed based on aquaporin water channels, and mussel inspired catecholamines for high-performance separation membranes. This review also evaluates these technologies identifying recent progresses and commercial aspects in nanofiltration and reverse osmosis applications.

Real-time probing of mercury using an efficient “turn-on” strategy with potential as in-field mapping kit and in live cell imaging

Based on a rhodamine scaffold as a fluorophore and 2-aminothiazole as a receptor, we present a highly selective and sensitive sensor (TS). An enhanced photophysical response (fluorescence as well as absorption) accompanied by high sensitivity and selectivity was observed upon interaction of TS with Hg2+ among various competitive cations (Ag+, Al3+, Ba2+, Ca2+, Co3+, Co2+, Cd2+, Fe3+, Fe2+, K+, Li+, Mg2+, Mn2+, Cu2+, Pb2+, Ni2+, Na+ and Zn2+) in CH3CNu2006:u2006H2O (7u2006:u20063 v/v, HEPES buffer 10 mM pH 7.0). The synthesized sensor can detect Hg2+ as low as 0.326 μM with a complexation constant of 2.37 × 106 M−1. This complexation between TS and Hg2+ is reversible in the presence of ethylenediaminetetraacetate (EDTA). Furthermore, single crystal X-ray diffraction (XRD) and Jobs plot results show a 1u2006:u20061 binding stoichiometry. The most interesting feature of the sensor is the real-time determination of Hg2+ in real contaminated water. Furthermore, the fabricated sensor can be employed as an intracellular monitoring agent for live cell imaging of the HeLa cell line.