Insight into the synthesis and mechanism of oxacalix[4]arene based nanohybrids for dual readout sensing and removal of Hg2+ ions

Mercury contamination has been a major concern for decades and its removal from environment and natural waterbodies are of highest priority. Inspired by the fact to detect trace amount of mercury and consequently removal of the same, here we present a silver nanoparticle based affordable, rapid and sensitive probe for inspecting the mercury levels on various waterbodies and soil samples with exceptional sensitivity (12 nM). This study reports the design, synthesis and characterization of novel disulfonic acid functionalized oxacalix[4]arene appended silver nanoparticles (DSOC@AgNPs). Driven by the distinct color change phenomena of DSOC@AgNPs upon interaction with Hg2+ ions, we have fabricated a paper strip-based ready-to-use detection kit for rapid detection of mercury ions up to sub-nanomolar concentration. Moreover, DSOC@AgNPs modified screen-printed carbon electrodes (SPCE) have been developed and utilized as a rapid detection kit for mercury in environmental samples. DSOC@AgNPs encapsulated ZIF-8 nanohybrid (DSOC@AgNPs-ZIF) have been employed for the removal of Hg2+ ions from mercury contaminated wastewater with a removal efficiency of 95%. Incidentally, this is the first report for the removal of Hg2+ ions (CH3Hg+ and Hg2+ species) using oxacalixarene-stabilized AgNPs. Further, the surface-modified Rh6G-DSOC@AgNPs reveal its bio-imaging potentiality for mercury detection in living systems and also exhibited dose-dependent cytotoxicity against MCF-7 cells, with an IC50 value of 354.62 μM. [Display omitted] •DSOC@AgNPs was synthesized for the detection of CH3Hg+ and Hg2+ ions with exceptional sensitivity.•Rhodamine 6 G modified DSOC@AgNPs (Rh6G-DSOC@AgNPs) was employed for in vitro sensing of mercury ions.•DSOC@AgNPs embedded ZIF-8 nanohybrid was used to remove mercury ions from contaminated waterbodies.•A screen-printed carbon electrode modified with DSOC@AgNPs has been utilized to recognise trace amounts of mercury.