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Potassium ions play pivotal roles in biological systems. A simple and effective Raman scattering-based protocol for the detection of physiological potassium ions level in human serum has been developed. We employed sodium cobaltinitrite, which can react with potassium to form potassium-sodium cobaltinitrite. Combining hydrophobic surface and the Raman scattering for potassium detection, highly reproducible Raman spectra of the potassium-sodium cobaltinitrite can be obtained with highly sensitivity. The characteristic Raman peak of potassium-sodium cobaltinitrite was used to distinguish it from other kinds of matter, and its intensity was used to monitor the amounts of potassium ions in human serum. Because of the contribution of the hydrophobic surface aggregation to the Raman, this protocol has great potential for practical detection of the potassium in human serum and has extended the measuring potential use in the detection of potassium in human serum by spectrum method. [ABSTRACT FROM AUTHOR]

In this paper, 4-mercaptobenzoic acid (4-MBA/pMBA) was designed as a model molecule for theoretical and experimental studies of the molecule structure. Density functional theory (DFT) calculations have been performed to predict the IR and Raman spectra for the molecule. In addition, Fourier transform infrared (FTIR) and Raman spectra of the compound have been obtained experimentally. Based on the modeling results obtained at the B3LYP/6-311++G ∗∗ level, all FTIR and Raman bands of the compound obtained experimentally were assigned. Our calculated vibrational frequencies are in good agreement with the experimental vales. The molecular electrostatic potential surface calculation was performed and the result suggested that the 4-MBA had two hydrogen bond donors and three hydrogen bond acceptors. HOMO–LUMO gap was also obtained theoretically at B3LYP/6-311++G ∗∗ level. [ABSTRACT FROM AUTHOR]

Abstract: We report on the joint application of fluorescence, ultraviolet–visible (UV–Vis) and Raman spectroscopy to the study of berberine with human serum albumin (HSA). We propose the surface-enhanced Raman scattering (SERS) technique to improve the understanding of the quenching interaction caused by berberine which could be applied in recognition process of fluorescent drugs with large biomolecules. The fluorescence and UV–Vis spectroscopic results show that the fluorescence intensity of HSA is significantly decreased in the presence of berberine, and the quenching mechanism is static. The SERS technique demonstrates clear advantages over direct measurements in physiological conditions. By means of this method, we are able to deduce important information concerning the binding property of berberine when interacting with HSA. We show the nitrogen atom is free but the dioxolane is involved in the spontaneously electrostatic inducement and subsequently hydrophobic binding. [ABSTRACT FROM AUTHOR]

[Display omitted] • A fundamental analysis of 4-CPH is proposed systematically. • The protonation of 4-CPH involves a depolarization effect. • A pH-dependent frequency shift of cyano in 4-CPH is observed and interpreted. 4-Cyanophenylhydrazine (4-CPH) is an organic synthesis intermediate. To date, several products derived from 4-CPH have been well studied; however, 4-CPH itself has not been extensively investigated. Herein, we performed vibrational and theoretical analyses of 4-CPH. Density functional theory (DFT) calculations were applied to predict the IR and Raman spectra of 4-CPH, which were compared with the experimental spectra. The calculated and experimental spectral results were in good agreement, except for an abnormal transformation of the protonated 4-CPH cyano group (C≡N), which was observed in the theoretical IR spectrum. Several wavefunction analyses revealed that this transformation was due to the protonation-induced depolarization of the molecule. Moreover, we verified the applicability of 4-CPH as a probe for surface-enhanced Raman spectroscopy (SERS). We observed a pH-dependent shift in the cyano bond frequency within the silent region and determined, as a novel discovery, that this shift was induced by 4-CPH protonation. Our results provide considerable, fundamental information that confirms the potential of 4-CPH as a SERS probe. [ABSTRACT FROM AUTHOR]