The morphology and physicochemical properties of polydopamine are not totally inherent and undergo changes with differing reaction conditions like the choice of solvent used for polymerization. The polymerisation of dopamine to polydopamine carried out in different solvents like sodium hydroxide, sodium bicarbonate, PBS and Tris leads to polydopamine with exceptionally different morphological and physicochemical features with each solvent. Additionally, the different physicochemical characteristics and morphologies bestow the polymer films with different extents of antimicrobial activity. Moreover, the findings supported by chemical evidence from X-ray photoelectron spectroscopy reveal that higher antibacterial activities were obtained against E. coli and S. aureus with polydopamine films prepared by Tris and NaOH solvent induced polymerization. The antibacterial activity observed in saline was found to be higher than that in PBS medium for both E. coli and S. aureus. The higher antibacterial activity of polydopamine films prepared in Tris and NaOH solvents was attributed to the covalent incorporation of -OH groups on the surface provided by nucleophilic Tris and NaOH solvents during the polymerisation process. The distinct physicochemical and morphological changes were supported by the results from contact angle measurements, FE-SEM, EDAX, AFM, and XPS analysis. The present finding provides insight into the different chemistry, morphologies and properties of the designed polydopamine films with controlled antibacterial/antifouling properties. Additionally, new insights into the mechanism of formation, physicochemical changes in morphology and properties of polydopamine coatings were revealed.

Inorganic sulphidenanoparticles (NPs) were prepared by wrapping the magnetic iron oxide NPs with thin shell (5 nm) of zinc sulphide. The as prepared NPs show maximum mercury removal capacity of 98-99% under ambient conditions from tap, ground and polluted river water without any pre-treatment. The magnetic nanoparticlesinteract with toxic mercuric ions predominately by adsorption phenomenon and shows excellent thermodynamic parameters fitted with Langmuir and van'thoff isotherms. The as prepared magnetic NPshave high selectivity for mercury, practical utility and can be scaled up at pilot scale.

Inspired by the biochemical reaction of of L‐4‐Thiazolidinecarboxylic acid (thioproline, TCA) with nitric oxide in human body, a novel method was developed to quantify the NO2− in biological matrix at very high sensitivity and selectivity. The developed assay has added advantage over traditional Griess reagent and can be employed for the clinical assays of NO2− at room temperature using thioproline.