Soumya Haldar

Siderophore coated magnetic iron nanoparticles: Rational designing of water soluble nanobiosensor for visualizing Al3+ in live organism

This article aims to establish the judicious use of iron-binding chemistry of microbial chelators in order to functionalize the surface of iron nanoparticles to develop non-toxic nanobiosensor. Anchoring a simple siderophore 2,3-dihydroxybenzoylglycine (H3L), which bears catechol and carboxyl functionalities in tandem, on to the surface of Fe3O4 nanoparticles has developed a unique nanobiosensor HL-FeNPs which showed highly selective and sensitive detection of Al3+ in 100% water at physiological pH. The biosensor HL-FeNPs, with 20nM limit of detection, behaves reversibly and instantly. In-vivo bio-imaging in live brine shrimp Artemia confirmed that HL-FeNPs could be used as fluorescent biomarker for Al3+ in live whole organisms. Magnetic nature of the nanosensor enabled HL-FeNPs to remove excess Al3+ by using external magnet. To our knowledge, the possibility of microbial chelator in the practical development of Al3+ selective nanobiosensor is unprecedented.

Enhanced bacterial affinity of PVDF membrane: its application as improved sea water sampling tool for environmental monitoring

AbstractIsolation of diversified bacteria from seawater is a major challenge in the field of environmental microbiology. In the present study, an attempt has been made to select specific membrane with improved property of attaching diversified bacteria. Initially, different concentrations (15, 18, and 20% W/W) of polysulfone (PSF) were used to check their affinity for the attachment of selected gram-positive (Bacillus subtilis) and gram-negative (Escherichia coli) bacteria. Among these, 20% W/W PSF showed maximum attachment. Therefore, membrane prepared with other materials such as polyvinylidene fluoride (PVDF) and polyether sulfone (PES) were used with the same concentration (20% W/W) to check their improved bacterial attachment property. Comparative study of bacterial attachment on three different membranes revealed that PVDF possessed the highest affinity towards both the groups of bacteria. This property was confirmed by different analytical methods viz. contact angle, atomic force microscopy, zeta potential, and flux study and further validated with seawater samples collected from seven sites of western coast and Lakshadweep island of India, using Biolog EcoPlate™. All the samples showed that bacterial richness and diversity was high in PVDF membrane in comparison to surrounding seawater samples. Interestingly, affinity for more diversified bacteria was reported to be higher in water sample with less turbidity and low bacteria load. This finding can facilitate the development of PVDF (20% W/W) membrane as a simple, cheap, and less labor intensive environmental sampling tool for the isolation of diversified bacteria from seawater sample wih different physiochemical properties. Graphical abstractᅟ

Monitoring metabolite change in ice stored ghol fish (Protonibea diacanthus) by using a 1H NMR technique: identification of pyruvate as a spoilage marker

Proton nuclear magnetic resonance (1H NMR) spectroscopy based metabolic analysis of ghol fish (Protonibea diacanthus) tissue extracts was carried out to acquire information on quality changes in fish samples during their prolonged storage in ice soon after sea-catch. This study revealed a wide distribution of metabolic signatures with the post-mortem age of ice stored fish. Up to 4 days (D-4) of ice storage, there were little changes in the concentration of a few selected metabolites such as trimethylammonium oxide (TMAO), creatine/phosphocreatine, and pyruvate; however, the concentration of the latter increased significantly afterwards.