Abstract
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In order to develop optical Hg(II) sensors, the adsorption characteristics of poly-L-lysine (PLL) after the conjugation of various ions on gold nanoparticles (AuNPs) were examined by means of Raman spectroscopy, UV-Vis absorption, and quasi-elastic light scattering (QELS). The intensities of the two bands at 458 and 1115 cm-1 appeared to decrease, in comparison with that at 1150 cm-1 in the presence of 100 關M of Hg(II). The other ions of Cr3++, Pb2++, Mn2++, Zn2++, Co2++, Ni2++, Cd2++, Fe2++, Na++, K++, Ca2++, Mg2++, Cu2++, NH4++, and Fe3++ did not show such spectral changes. The prominent band at 1150 cm-1, which may be ascibed to the C-N or 款 (NH3++) band, suggests that a conformational change of poly-L lysine (PLL) occurs after its interaction with Hg(II) ions. The Hg(II) concentration-dependent SERS spectra indicated that the relative intensities of the two bands at 458 and 1115 cm-1 decreased and that at 1150 cm-1 increased above 1 關M. These vibrational fingerprints may be useful to discriminate the Hg(II) ion above 1 關M using AuNPs and Raman spectroscopy. On the basis of the presented spectroscopic study, we plan to develop an efficient method of detecting the Hg(II) ion at lower concentrations by introducing a variety of SERS platforms. |