Electrochemical detection of monosodium glutamate in foodstuffs based on Au@MoS2/chitosan modified glassy carbon electrode.

We report an amperometric immunosensor for the detection of monosodium glutamate (MSG) using a glassy carbon electrode modified with gold nanoparticle decorated on a molybdenum disulfide/chitosan (Au@MoS2/Ch) nanocomposite. In the present detection technique, Au@MoS2/Ch was used as a conductive matrix and anti-glutamate antibody was immobilized on to its surface via carbodiimide coupling method. Chemical and morphological attributes of the various components of the immunosensor were confirmed by UV-vis spectroscopy, SEM, TEM and XRD analysis. Electrochemical characterizations were carried out by CV, DPV and EIS. Overall results showed the effective fabrication of highly conductive Au@MoS2/Ch nanocomposite for sensitive electrochemical detection of MSG. A linear relationship was perceived between the change in current and concentration of MSG. The relationship was found to be consistent in the detection range of 0.05-200 µM. Statistical validation of the assay showed limit of detection and limit of quantification values as 0.03 and 0.1 µM, respectively (R2 = 0.99).

Cellulose-metallothionein matrix for metal binding.

In this report, we have modified bacterial cellulose to a metal binding matrix by covalently conjugating physiological metal chelators known as metallothioneins. The hydroxyl groups of the native bacterial cellulose from Gluconobacter xylinus are epoxidized, followed by the covalent conjugation with the amine groups of the proteins. For the first time, a covalent conjugation of protein with bacterial cellulose is achieved using the epoxy-amine conjugation chemistry. Using this protocol, 50% mass by mass of the metallothionein could be attached to bacterial cellulose. The morphological features and porosity of the modified cellulose are different compared to pristine bacterial cellulose. Also, the conjugated material has better thermal stability. A five-fold enhancement in the metal binding capacity of the metallothionein conjugated bacterial cellulose is achieved as compared to pristine bacterial cellulose. Cellular metabolic assay and membrane integrity assay on MCF and HeLa cell lines showed no significant toxicity of the conjugate material. This bacterial cellulose-metallothionein conjugate can be explored for health care applications where management of metal toxicity is crucial. Further, the epoxy-amine chemistry for covalent conjugation of protein can be applied for several other types of proteins to develop specific functional biocompatible and biodegradable cellulose matrices.

Plant extract-mediated green silver nanoparticles: Efficacy as soil conditioner and plant growth promoter.

Recently, concerns have been raised regarding the ultimate fate of silver nanoparticles (SNPs) after their release into the environment. In this study, the environmental feasibility of plant leaf (Thuja occidentalis) extract-mediated green SNPs (GSNPs) was assessed in terms of their effects on soil physicochemical properties and crop growth in comparison to conventionally synthesized silver nanoparticles (CSNPs). Upon application of GSNPs, soil pH shifted toward neutrality, and substantial increments were observed in water holding capacity (WHC), cation exchange capacity (CEC), and N/P availability. The mechanism behind the enhanced availability of N was verified through lab-scale experiments in which GSNP-treated soils efficiently resisted nitrate leaching, thereby sustaining N availability in root zone soil layers. However, retardation in nutrient availability and enzyme activity was apparent in soils treated with 100 mg kg-1 of either CSNPs or GSNPs. Remarkable improvements in leaf area index (LAI), leaf number, chlorophyll content, nitrate reductase (NR) activity, and Phaseolus vulgaris pod yield were observed after the application of low doses of GSNPs (25-50 mg kg-1). The true benefit of GSNP application to soil was substantiated through experiments on plant uptake of nutrients, NR expression, and ferredoxin gene expression in P. vulgaris leaves.

Silver Nanoparticles as Antibacterial and Anticancer Materials Against Human Breast, Cervical and Oral Cancer Cells.

Silver nanoparticles contribute a giant share to the realm of modern nanobiotechnology. Their utility as antimicrobial agents is also well documented. Green synthesis of nanoparticle has several advantages over its chemical synthesis. In the present study, Thuja occidentalis leaf extract mediated silver nanoparticles were prepared without using a stabilizing agent and tested for their anticancer and anti-microbial activity. Thuja occidentalis leaf extract mediated silver nanoparticles were prepared under ambient conditions which showed a narrow size distribution within the range of 10­15 nm, with average particle size of 12.7 nm. Interestingly, these nanoparticles exhibited anti-cancer activity against human breast (MCF 7, MDA MB 231) and cervical cancer (HeLa) as well as mouth epidermoid carcinoma (KB) cell lines at a concentration range of 6.25­50 µg/mL. Contrarily, they are compatible with human peripheral blood mononuclear cells and rat hepatocytes. Moreover, their efficient inhibitory effect was witnessed against Bacillus subtilis, Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium and Pseudomonas aeruginosa with inhibitory concentration at 5­10 µg/mL. The prepared nanoparticles were highly biocompatible and have strong potential in the development of non-toxic chemotherapy with antibacterial attributes.

s-Triazine-based biocompatible hyperbranched epoxy adhesive with antibacterial attributes for sutureless surgical sealing.

Endeavors have been made over last few decades to relieve mankind from painful suturing during surgery, especially in the case of pediatrics. A few surgical sealants or tissue adhesives have been designed; however, biocompatibility and degradation concerns limit their use. Herein, an s-triazine-based hyperbranched epoxy, along with a poly(amido amine) hardener, was used to develop a highly biocompatible surgical sealant. The epoxy can be cross-linked up to 62% at room temperature. Furthermore, the sealant exhibited antibacterial activity against Staphylococcus aureus, the most notorious microorganism that causes surgical site infections. The sealant is degradable under physiological conditions and the degraded products are non-toxic. Thus, here we demonstrate the major merits of the present sealant such as high mechanical stability, optimum balance between strength and flexibility, biocompatibility and degradability.

Biocompatible high performance hyperbranched epoxy/clay nanocomposite as an implantable material.

Polymeric biomaterials are in extensive use in the domain of tissue engineering and regenerative medicine. High performance hyperbranched epoxy is projected here as a potential biomaterial for tissue regeneration. Thermosetting hyperbranched epoxy nanocomposites were prepared with Homalomena aromatica rhizome oil-modified bentonite as well as organically modified montmorillonite clay. Fourier transformed infrared spectroscopy, x-ray diffraction and scanning and transmission electron microscopic techniques confirmed the strong interfacial interaction of clay layers with the epoxy matrix. The poly(amido amine)-cured thermosetting nanocomposites exhibited high mechanical properties like impact resistance (>100 cm), scratch hardness (>10 kg), tensile strength (48-58 MPa) and elongation at break (11.9-16.6%). Cytocompatibility of the thermosets was found to be excellent as evident by MTT and red blood cell hemolytic assays. The nanocomposites exhibited antimicrobial activity against Staphylococcus aureus (ATCC 11632), Escherichia coli (ATCC 10536), Mycobacterium smegmatis (ATCC14468) and Candida albicans (ATCC 10231) strains. In vivo biocompatibility of the best performing nanocomposite was ascertained by histopathological study of the brain, heart, liver and skin after subcutaneous implantation in Wistar rats. The material supported the proliferation of dermatocytes without induction of any sign of toxicity to the above organs. The adherence and proliferation of cells endorse the nanocomposite as a non-toxic biomaterial for tissue regeneration.

Non-hazardous anticancerous and antibacterial colloidal 'green' silver nanoparticles.

Poly(ethylene glycol) stabilized colloidal silver nanoparticles were prepared using the reductive potency of the aqueous extract of Thuja occidentalis leaves under ambient conditions. The nanoparticles were well dispersed within a narrow size spectrum (7-14 nm) and displayed characteristic surface plasmon resonance peak at around 420 nm and Bragg's reflection planes of fcc structure. MTT assay revealed the dose-dependent cytocompatibility and toxicity of the nanoparticles with the L929 normal cell line. On the other hand, the antiproliferative action of the nanoparticles was evaluated on HeLa cell (cancerous cells) line. Fluorescence and phase contrast microscopic imaging indicated the appearance of multinucleate stages with aggregation and nuclear membrane disruption of the HeLa cells post treatment with the nanoparticles. The interaction at the prokaryotic level was also assessed via differential antibacterial efficacy against Staphylococcus aureus (MTCC 3160) and Escherichia coli (MTCC 40). Under these perspectives, it is also necessary to observe the environmental impact of the prepared silver nanoparticles. Hence, the dose dependent toxicity of silver nanoparticles was evaluated upon the earthworm species Eisenia fetida. Neither the survival nor the reproduction was affected by the addition of silver nanoparticles up to 1000 ppm. Thus these 'green' silver nanoparticles have promising potential as future materials.