Au nanoparticles functionalized 3D-MoS2 nanoflower: An efficient SERS matrix for biomolecule sensing.

The surface-enhanced Raman scattering spectra of biliverdin and bilirubin were obtained and analyzed; a physical silver ligand interaction was inferred. The structural conformation of biliverdin is practically the same when passing from the dry to solution relative to that observed in Raman solid. However, the surface effect induces a different molecular orientation on the surface in dry and in solution. The conformational structure of bilirubin is modified when passing from dry to solution conditions; the orientation of the analyte on the surface is different in both media. The carboxylate groups interact with the surface more closely in bilirubin than in biliverdin. The unsaturated methine bridge in biliverdin confers an additional stability by delocalizing the π-electronic cloud. Both sides of the molecule could be in the same plane. On contrary, bilirubin with a tetrahedric carbon (methylene bridge) confers the whole system a rather free rotation of each side of the whole molecule. Theoretical...

Surface-enhanced Raman scattering and theoretical study of the bilichromes biliverdin and bilirubin

s of Papers, 232nd ACS National Meeting, San Francisco, CA, United States, Sept. 10-14, 2006, 2006: p. COMP-118. 200. Jensen, L. and G.C. Schatz, Resonance Raman Scattering of Rhodamine 6G as Calculated Using Time-Dependent Density Functional Theory. Journal of Physical Chemistry A, 2006. 110(18): p. 5973-5977. 201. Jia, H., W. Xu, J. An, D. Li, and B. Zhao, A simple method to synthesize triangular silver nanoparticles by light irradiation. Spectrochimica Acta, Part A: Molecular and Biomolecular Spectroscopy, 2006. 64A(4): p. 956-960. 202. Jia, H., J. Zeng, W. Song, J. An, and B. Zhao, Preparation of silver nanoparticles by photo-reduction for surface-enhanced Raman scattering. Thin Solid Films, 2006. 496(2): p. 281-287. 203. Jia, S.-J., S.-P. Xu, X.-L. Zheng, B. Zhao, and W.-Q. Xu, Preparation of SERS optical fiber sensor via laser-induced deposition of Ag film on the surface of fiber tip. Gaodeng Xuexiao Huaxue Xuebao, 2006. 27(3): p. 523-526. 204. Jiang, X., Y. Wang, X. Qu, and S. Dong, Surface-enhanced resonance Raman spectroscopy and spectroscopy study of redox-induced conformational equilibrium of cytochrome c adsorbed on DNA-modified metal electrode. Biosensors & Bioelectronics, 2006. 22(1): p. 49-55.

SUPPLEMENTARY INFORMATION References to Surface-Enhanced Vibrational Spectroscopy

Biliverdin (BV), a product of heme catabolism, is known to interact with transition metals, but the details of such interactions under physiological conditions are scarce. Herein, we examined coordinate/redox interactions of BV with Cu2+ in phosphate buffer at pH 7.4, using spectrophotometry, HESI-MS, Raman spectroscopy, 1H NMR, EPR, fluorimetry, and electrochemical methods. BV formed a stable coordination complex with copper in 1 : 1 stoichiometry. The structure of BV was more planar and energetically stable in the complex. The complex showed strong paramagnetic effects that were attributed to an unpaired delocalized e−. The delocalized electron may come from BV or Cu2+, so the complex is formally composed either of BV radical cation and Cu1+ or of BV radical anion and Cu3+. The complex underwent oxidation only in the presence of both O2 and an excess of Cu2+, or a strong oxidizing agent, and it was resistant to reducing agents. The biological effects of the stable BV metallocomplex containing a delocalized unpaired electron should be further examined, and may provide an answer to the long-standing question of high energy investment in the catabolism of BV, which represents a relatively harmless molecule per se.

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Biliverdin-copper complex at physiological pH.

Interface synthesis of MoS2@ZnO@Ag SERS substrate for the ultrasensitive determination of bilirubin

Surface-Enhanced Raman Scattering (SERS) spectra of bilirubin–metal ion (Cu2+, Co2+, Zn2+, Cd2+) complexes (MBR) are reported. These spectra reveal significant differences between MBR and bilirubin (BR) itself. But SERS spectra of bilirubin–Cu2+, Co2+, Zn2+, Cd2+ complexes are similar to each other. The mole ratio of bilirubin-metal in the complexes M2+ : BR = 1 : 1 was measured. Empirical assignments of the major SERS bands are given. The spectrum of CuBR in solution is consistent with a square planar structure. It should be noted, however, that H2O or COOH of another BR molecule occupy the positions above and below the plane in solutions of complexes of this type and forms CuO bond.



By comparing the SERS spectra of bilirubin-copper (or zinc) and biliverdin-copper (or zinc) complexes, the similar Raman frequencies and relative intensities were attributed to the oxidation of the bilirubin-copper (or zinc) complex to the green biliverdin-copper (Zn) complexes. It is shown that . © 1995 John Wiley & Sons, Inc.

Xingyao Zhou

Papers

Surface-Enhanced Raman-Spectroscopy of Bilirubin-Metal Ion Complexes