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A novel, pH‐responsive supramolecular graft copolymeric micelle, composed of dextran and poly (oleic acid), has been synthesized through reversible addition fragmentation chain transfer polymerization with controlled Mn and narrow polydispersity. The structural properties of the copolymer have been studied using FTIR and 1H NMR spectral analyses. Critical micelle concentration (CMC) has been determined fluorometrically and conductometrically. The copolymer shows pH responsive micellar stability, which has been confirmed using DLS study. Dextran‐g‐OA copolymer demonstrates spherical morphology at CMC, while rod‐like assembly has been evidenced beyond CMC that is probably because of the structural alteration of copolymeric chains at higher copolymer concentration. Dextran‐g‐OA is noncytotoxic toward MG‐63 cells. As the self‐assemble nature of copolymer micelle promotes the oral administration of hydrophobic drugs, nifedipine (NFD, a hydrophobic drug) has been used as model drug that has been encapsulated substantially into the core of the micelle. The copolymer releases the loaded NFD at a much slower rate in simulated gastric fluid (pH 1.2) and relatively faster in simulated intestinal fluid (pH 7.4) with a cumulative release of ~95% within 24 h, suggesting an ideal candidate as nifedipine carrier. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2354–2363

The new signaling probes 2-6, rhodamine-B derivatives of various receptors which contain different donor atoms for effective metal ion coordination, were synthesized and their absorption as well as fluorescence spectral responses were evaluated in the presence of various metal ions. All these probes along with the reference probe 1 have exhibited optimal metal ion-induced absorption and fluorescence enhancement with Hg(II) ion in the longer wavelength region (>500 nm) in MeCN, exploiting the spectral characteristics of metal ion-induced structural transformation of rhodamine. The selectivity and sensitivity towards Hg(II) ion were better pronounced in MeCN-H(2)O (1 : 1 v/v) medium, implying the role of the solvent molecules, water in particular, in the preferential Hg(II) coordination environment. Complexation of Hg(II) to 1-6 not only enhanced the absorption at ~560 nm, which turned the colourless solution into pink to facilitate a naked eye detection, but also amplified the fluorescence intensity simultaneously to offer high sensitivity of detection at lower concentration. The Hg(II)-induced photo-physical spectral responses of 1-6 in presence of other competitive metal ions rendered their high selectivity towards Hg(II). Further, their reversible dual channel signaling pattern under the action of counter anions, exploiting coordination tendency of anions towards Hg(II), which compete with probe-metal interaction, implied the reversibility in their Hg(II) coordination. The selectivity, sensitivity and reversibility, in principle, establishes the potential of these probes as chemosensors for Hg(II) ion detection.

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