Jhuma Ganguly

Exopolymers from Tolypothrix tenuis and three Anabaena sp. (Cyanobacteriaceae) as novel blood clotting agents for wound management

Rapid initiation of clotting is critical to trauma patients. In the present study exopolymers (EPs) from four desert cyanobacteria including Tolypothrix tenuis and three species of Anabaena have been discovered as potential hemostatic biomaterials. The EPs showed reduction in activated partial thromboplastin time (APTT) and prothrombin time (PT) by 16-41% and 12-65%, respectively. Besides hastening blood clotting, the EPs could absorb 7.1-25.9 g H₂O g(-1) EP and displayed 7.1-18.1% hydrophobicity. They were noncytotoxic and biodegradable. The EP from Anabaena sp. showed strong antibacterial activity against E. coli, S. aureus and B. licheniformis. These results suggest that cyanobacteria, the microscopic phototrophs growing rapidly over simple mineral medium could prove to be a novel source of affordable hemostatic dressings for the traumatic wounds in underdeveloped and developing countries. Compositional analysis of the EPs showed them to be consisting of mainly carbohydrate (17-50%), protein (4.4-7.2%), uronic acid (4.7-9.5%) and sulphate (0.6-6.6%). Their viscometric molecular weight ranged from 539 to 3679 kDa. They were further characterized using GC-MS and FTIR.

A dynamic chitosan-based self-healing hydrogel with tunable morphology and its application as an isolating agent

A biopolymer chitosan based 3D hydrogel framework (ChF) with good transparency and rapid self-healing activity has been successfully synthesized and utilized to get high purity separation of long-lived fission products 152Eu (T1/2 = 13.33 a) and 137Cs (T1/2 = 30.17 a) employing solid liquid extraction (SLX) technique. The unique properties of covalently cross-linked polymeric ChF have been analyzed through FT-IR, solid-state 13CP/MAS NMR, rheological measurement, SEM, AFM, TG-DTG, DSC, XRD and swelling study. Rheological analysis reveals that the maximum mechanical strength of a hydrogel is achieved upon synthesis using 1 : 0.43 chitosan to formaldehyde stoichiometry (ChF3). A plateau of storage modulus (G′), over a wide range of angular frequency of ChF reveals its visco elastic nature. On varying the cross linking of the hydrogel network, we found a precise tuning of morphology and properties of ChF. This ChF was utilized to separate 152Eu from a mixture of 152Eu and 137Cs in aqueous HCl medium (pH 5) using SLX technique and it was observed that ChF specifically adsorbs 152Eu without any contamination from 137Cs. 152Eu was back extracted easily using 1 M aqueous HCl from 152Eu-adsorped-ChF. The adsorption of 152Eu on ChF is influenced by pH, amount of hydrogel, time of contact, temperature, cross-linking density and dosage of γ-radiation. To establish the self-healing property of the gels, rheological analysis through step-strain measurements (strain = 0.1 to 100%) at 25 °C was monitored. The polymeric hydrogel network displays a reversible sol–gel transition for several cycles due to the dynamic equilibrium between the Schiff base linkage and the aldehyde and amine functional groups.

Biosynthesis, characterisation and antimicrobial activity of silver and gold nanoparticles byDolichos biflorusLinn seed extract

ABSTRACT The bioreduction method employed for the synthesis of colloidal AgNPs and AuNPs is reported here. Methanolic and aqueous extracts of Dolichos biflorus Linn seed was used as the bio-reducing agent. The structural and morphological aspects of the synthesised metal nanoparticles were investigated using X-ray diffraction (XRD), energy-dispersive spectroscopy (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD, revealed crystalline nature of the synthesised particles, UV–vis spectrophotometric analysis showed characteristic absorption peak for both AgNPs and AuNPs. EDX analysis confirmed the presence of elemental silver and gold particles and the average size and morphology were determined by SEM and TEM. The synthesised AgNPs exhibited good antibacterial potential whereas AuNPs showed poor activity against human pathogenic, gram-positive bacteria such as Staphylococcus aureus, Bacillus subtilis and gram-negative bacteria, such as Escherichia coli, Pseudomonas aeruginosa.

Selective separation of 152Eu from a mixture of 152Eu and 137Cs using a chitosan based hydrogel

A rapid and novel technique was developed to separate long-lived fission products 152Eu (T1/2 = 13.33 years) and 137Cs (T1/2 = 30.17 years) using a solid liquid extraction (SLX) technique with a chitosan biopolymer based hydrogel (ChG). In this technique, ChG selectively adsorped 152Eu (∼87%) from the mixture of 152Eu and 137Cs without any contamination of 137Cs. Simple back extraction using 1 M aqueous HCl from 152Eu-adsorped-ChG leads to pure 152Eu (∼72%). The adsorption behavior of 152Eu on ChG depends on pH and radiation dose. The structural, mechanical, thermal and morphological characterization of ChG was confirmed by FT-IR, solid state NMR, rheology measurement, SEM, TG-DTG, DSC and XRD studies. The rheological study shows a higher value of the storage modulus (G′) than the loss modulus (G′′), demonstrating that the rheological behavior in the ChG has a majority of visco elastic solid nature.

Characterization of a fluorescent hydrogel synthesized using chitosan, polyvinyl alcohol and 9-anthraldehyde for the selective detection and discrimination of trace Fe3+ and Fe2+ in water for live-cell imaging

A three-dimensional fluorescent hydrogel based on chitosan, polyvinyl alcohol and 9-anthraldehyde (ChPA) has been successfully designed and synthesized for the selective detection and discrimination of Fe3+ and Fe2+ in aqueous environment. The unique characteristics of ChPA has been confirmed by the Fourier-transform infrared spectroscopy (FTIR), rheological measurement, scanning electron microscopy (SEM), thermogravimetry and differential thermogravimetry (TG-DTG), ultraviolet-visible spectroscopy (UV-vis), fluorescence studies, transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDX), x-ray diffraction (XRD) and dynamic light scattering (DLS). The emission intensity at 516 nm of the hydrogel has been enhanced remarkably with the addition of Fe3+ due to the inhibition of the photoinduced electron transfer (PET) process. However, it gets strongly quenched in the case of Fe2+ owing to chelation enhanced quenching (CHEQ). The probe (ChPA) causes no significant change in the fluorescence and becomes highly specific and sensitive towards Fe3+ and Fe2+ compared to other interfering heavy and transition metal ions (HTM). The detection limits of the sensor for the Fe3+ and Fe2+ are 0.124 nM and 0.138 nM, respectively. The probe is also promising as a selective sensor for the Fe3+ and Fe2+ in the fluorescence imaging of living cells. Thus, such a probe opens up new opportunities to improve the chitosan based fluorescent chemosensor having biocompatibility, biodegradability, sufficient thermal stability and stability in a wide pH range.

Green synthesis and swelling behavior of Ag-nanocomposite semi-IPN hydrogels and their drug delivery using Dolichos biflorus Linn

ABSTRACT Acrylic-based hydrogels with great potentials for usage in medical area were principally synthesized as per two strategies. The first involved reaction containing silver nitrate to yield silver nanoparticles (AgNPs) where Dolichos biflorus Linn acted as both reducing agent and stabilizing for green synthesized AgNPs was added to the reaction medium to establish reduction of Ag+ to AgNPs. The second strategy entailed preparation of nanosilver composite hydrogel that is carried out by free radical polymerization reaction in presence of Sodium Alginate and acrylamide (AAm) under the same conditions. In both strategies, factors affecting the characterization of AgNPs-loaded hydrogels were studied. Analysis and characterization of the so obtained hydrogels were performed through monitoring swelling behavior, FTIR spectroscopy, SEM, EDX, UV–Vis spectrophotometer, XRD, and TEM. Results indicate that modifying AAm and silver ion can improve swelling properties of the resultant nanocomposite hydrogel. pH response of this nanocomposite hydrogel in different pH made it suitable for drug delivery applications.

A dynamic sugar based bio-inspired, self-healing hydrogel exhibiting ESIPT

The development of a bioactive hydrogel that acts as a cell carrier can overcome current limitations in cell therapy. However, the hydrogels usually have a tendency to get damaged during use, and they sometimes also pose a real threat of cell apoptosis. Therefore, the present work has been performed to develop a bio-inspired, self-healing chitosan-5-(benzo[d]thiazol-2-yl)-4-hydroxyisophthalaldehyde (CBTHP) fluorescent hydrogel. The physico-chemical properties of this polymeric hydrogel have been characterized by using FT-IR spectroscopy, solid state 13C NMR, rheological analysis, SEM, TEM, DLS, UV-Vis spectroscopy, fluorescence spectroscopy, TGA and swelling study. CBTHP exhibits ultrafast excited state intramolecular proton transfer (ESIPT) through keto–enol tautomerism in both the gel and solution phase. The dynamic equilibrium between the Schiff base linkages between the aldehyde and amine reactants introduces the self-healing property in the hydrogel. The self-healing property of the hydrogel has also been monitored by rheological analysis through step-strain measurements (strain 0.1 to 100%) at 25 °C. The polymeric hydrogel network exhibits a reversible sol–gel transition for several cycles owing to the dynamic equilibrium between the Schiff base linkages. The cellular uptake and cell imaging efficiency suggest that as compared to other fluorescent materials, the formulation of this bio-inspired hydrogel can enable more molecules to enter the cells and thereby causing a greater intensity of fluorescence.

A regular rippled pattern formed by the molecular self-organization of polyvinylpyrrolidone encapsulated Ag nanoparticles: a high transmissive coating for efficiency enhancement of c-Si solar cells

The formation, characterization and application of polyvinylpyrrolidone (PVP) encapsulated silver nanoparticles with a regular rippled pattern is reported. The metal precursor was reduced by an in situ reduction technique, where glucose was used as an organic and mild reducing agent to control the process. In order to create the rippled structured of the film by molecular self organization of the encapsulated Ag nanoparticles, the concentrations of the reactants were optimized. The structural properties of the deposited films were established by X-ray diffraction, transmission electron microscopy, atomic force microscopy and dynamic light scattering techniques. Atomic force microscopy (AFM) revealed a highly ordered ripple structure of the film, which originated due to the self organization of the Ag nanoparticles in the PVP matrix, whereas, transmission electron microscopy (TEM) revealed the core–shell structure of the Ag/PVP unit. UV-vis spectrophotometric analysis resulted in a broad absorption peak between 350 to 500 nm (centered at 418 nm), which is characteristic of Ag nanoparticles. A notable reduction in reflectance and an increase in transmittance, leading to an enhancement in the overall efficiency, were observed when the rippled pattern was spin-coated on a c-Si solar cell.

Green and Environmental Friendly Domain and Discipline: Emerging Trends and Future Possibilities

Green Science and Technology is one of the important agenda for building eco friendly institutions, organization and Governance system. Today many domain are dealing with Green and environmental aspects for better and healthy sustainability. Among so many knowledge domain Green Computing, Green Information Technology, Green Business gain popularity. These domains are mainly responsible for the design and development of system and mechanism which may be manual or computational dedicated to Green and Eco Friendly environment creation. Many organization and institutions are engaged healthy strategy and policy towards building of Environmental health system and computing platform and to bring complete sustainability. This paper is about Green Science and Technology; their basic feature and importance. Paper is also illustrated future possibilities as academic programme on these domains.

Antioxidant Edible Mushrooms: A Green and Rapid Electrochemical Study with the Aqueous Extracts

A greener and rapid electrochemical technique was performed by indium doped tin oxide (ITO) glasses as working electrode in cyclic and differential pulse voltammetry to screen the antioxidant activities of the aqueous extracts of different species of edible mushrooms Plureotus florida, Calocybe indica and Tricholoma gigantum found in West Bengal. The ITO glasses as electrode was very sensitive for the detection of electrical potentiality with 10 μl of 20 μg/ml (volume and concentration) concentration in phosphate buffer (pH 7.0) for the isolated aqueous extracts of mushrooms along with ascorbic acid and gallic acid as standards. In addition to the electrochemical study, the spectrophotometric assays were used to evaluate the antioxidant constituents, their reducing power and free radical scavenging ability of the extracts. The results obtained from both electrochemical and spectrophotometrical assays were in good agreement to each other for the detectable and significant range of antioxidant potentiality of these extracts. The present electrochemical ITO electrode method is a greener, efficient, cost effective, recyclable, and less cumbersome for detection of antioxidant properties of mushrooms compared to the other available electrochemical techniques.