ChemInform Abstract (sodium dodecyl sulfate).

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Recently,carbon-based nanomaterials have been attracted much interest among the scientific community due to its extraordinary properties and applications. Mostly the fluorescent carbon nanomaterials are prepared from commercially available precursors. In this work, develop a new strategy for producing carbon nanoparticles (carbon dots) using phosphoric acid as an activating agent from water hyacinth present in Assam, India. These carbon nanoparticles show green fluorescence under UV light, and the sizes are found below 10 nm. These carbon dots are applied as a fluorescence sensor for detecting the herbicide (pretilachlor) . The developed PL sensor is exclusively selective and sensitive for detection of this herbicide, and the limit of detection is found to be 2.9 μM.This sensor is also tested for real samples like soil contaminated with pretilachlor.

The redox potential of heme undecapeptide from cytochrome c (microperoxidase 11) in aqueous sodium dodecyl sulfate (sds), hexadecyltrimethylammonium bromide, and Triton X-100 surfactant micelles varied from ϩ2 mV at pH 3.0 to Ϫ222 mV at pH 9.0. The potentials at pH 7.0 were Ϫ114, Ϫ122, and Ϫ166 mV vs. the normal hydrogen electrode in the three surfactants. The nature of the axial ligands, spin state of iron, apolar nature of the local heme environment, and pH influence the potential in the micelles. Binding of histidine (HisH) of the peptide chain gave a negative shift of Ϫ60 mV, and deprotonation of co-ordinated HisH to histidinate gave a Ϫ100 mV shift of the potential in aqueous sds. At pH 5.0-6.0 the axial ligands to iron are H 2 O and HisH; deprotonation of coordinated H 2 O gave Ϫ65 mV shift of the potential. Interaction of hemin with surfactant gave a positive shift of the potential with respect to that in water. The diffusion coefficient of the undecapeptide (2.4 × 10 Ϫ7 cm 2 s Ϫ1 ) at pH 7.0 in the micelles is an order of magnitude smaller than that in water, indicating solubilisation of heme in surfactant solutions. The potential is strongly dependent on pH and is controlled by the uptake/release of protons at three sites: the unco-ordinated HisH of the peptide chain, the axially co-ordinated H 2 O and HisH ligands. The pK a values of these redox state-dependent ionisations in the iron() state are ca. 4.3, 6.3, and 8.3. The change in potential per unit change of pH (∆E/∆pH) was ca. Ϫ59 mV, which indicates proton-coupled electron transfer involving one electron and one proton.