| In recent years, resonance Rayleigh scattering (RRS), as a new analytical technique, has attracted more and more attention. A series of new resonance Rayleigh scattering (RRS) or resonance light scattering(RLS) ) methods for the determination of proteins have been developed. Most of them are based on the significant enhancement of RRS caused by the interaction of proteins with some dyes, and it is thought that the aggregation of the chromophores of dyes on biomacromolecules is the main reason of the scattering enhancement. Although the interactions of proteins with small molecules(such as metal ions and its inorganic complexes) are helpful to understand the biochemical properties of the proteins, those metal ions and its inorganic complexes do not have chromophores, and it is difficulty to investigate their absorption and fluorescence spectra. Therefore, there are rare reports about spectrophotometric and fluorometric methods using metal ions and its inorganic complexes as probes to determine proteins. Our studies found that when Hg(Ⅱ),Pd(Ⅱ),Cd(Ⅱ) reacted with excessive I- to form [HgI4]2-,[PdI4]2-,[CdI4]2- that further combined with proteins, the resonance Rayleigh scattering (RRS) and resonance nonlinear scattering (RNLS) (such as second-order scattering (SOS) and frequency doubling scattering (FDS)) intensities were enhanced greatly and new scattering spectra appeared. This work could provide new information for studying the interactions between proteins and [HgI4]2-,[PdI4]2-,[CdI4]2-, and created conditions for the determination of proteins using resonance light scattering method. Because [HgI4]2-,[PdI4]2-,[CdI4]2- do not have chromophores, it indicates that the aggregation of chromophores of dyes on biomacromolecules is not necessary for the significant enhancement of the scattering. Furthermore, our experiments showed that the enhanced RRS intensities were directly proportional to the concentrations of proteins. Therefore, this method was more suitable for determining trace amounts of proteins. The proteins have strong intrinsic fluorescence because they have tryptophan and tyrosine residues. Our study found that [HgI4]2- and the I3- formed by the reaction of Cr (Ⅵ) with excessive I- could react with proteins by virtue of electrostatic attraction and hydrophobic force to form ion-association complexes, and then the fluorescence of proteins were partly quenched. The fluorescence quenching extent (△F) was proportional to the concentration of metal ion. Therefore, a new method for the determination of trace amounts of metal ion has been developed.1. Resonance Rayleigh Scattering and Resonance Nonlinear Scattering Spectra of [HgI4]2- -protein Systems and Their Analytical ApplicationsIn 0.0035-0.0045 mol/L H2SO4 solution, proteins such as bovine serum albumin (BSA), human serum albumin (HSA), ovalbumin (OVA) and haemoglobin (HGB) could react with [HgI4]2- by virtue of electrostatic attraction and hydrophobic force to formion-association complexes. As a result, the resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS) intensities were enhanced greatly and the new scattering spectra appeared. The maximum RRS, SOS and FDS peaks were at 390 nm, 760 nm and 390 nm. The enhanced RRS, SOS and FDS intensities were directly proportional to the concentrations of proteins. The detection limits for the different proteins were 5.7-15.9 ng/mL for the RRS method, 8.2-15.4 ng/mL for the SOS method and 11.2-22.1 ng/mL for the FDS method, respectively. These methods can be used for the determination of trace amounts of proteins. In this work, the effects of interaction of [HgI4]2- with proteins on RRS, SOS and FDS spectral characteristics, intensities and the optimum conditions were investigated. Meanwhile, the influences of coexisting substances were tested and the results showed that the method exhibited a good selectivity. Based on the above researches, a highly sensitive, simple and rapid method for the determination of trace amounts of proteins by resonance light scattering technique was developed, which could be applied to the determination of proteins in human urine and serum samples with satisfactory results.2. Study on the Resonance Rayleigh Scattering and Resonance Non-linear Scattering Spectra of [PdI4]2-- -Protein Systems and Their Analytical ApplicationsIn the acid medium solution, proteins such as bovine serum albumin (BSA), human serum albumin (HSA), ovalbumin (OVA), haemoglobin (HGB), lysozyme (Lyso),γ-globulin (γ-G), a- chymotrypsin (a-Chy) and papain (Pap) could react with [PdI4]2- by virtue of electrostatic attraction and hydrophobic force to form ion-association complexes. As a result, the resonance Rayleigh scattering (RRS) and resonance nonlinear scattering (RNLS) such as second-order scattering (SOS) and frequency doubling scattering (FDS) intensities were enhanced greatly and new scattering spectra appeared. The maximum scattering peaks of RRS, SOS and FDS were at 367 nm, 720 nm and 370 nm, respectively. The enhanced RRS, SOS and FDS intensities were directly proportional to the concentrations of proteins. The detection limits for the different proteins were 2.4-11.8 ng/mL for RRS method, 9.5-47.9 ng/mL for SOS method and 4.6-18.5 ng/mL for FDS method. In this work, the influences of the interaction of [PdI4]2- with proteins on spectral characteristics of RRS, SOS and FDS were investigated and the optimum conditions were tested. Meanwhile, the effects of coexisting substances were tested and the results showed that the method exhibited a good selectivity. Based on the above researches, a highly sensitive, simple and rapid method for the determination of trace amounts of proteins by resonance light scattering technique has been developed. It can be applied to the determination of proteins in tablet, human serum and urine samples.3. Study on the Resonance Rayleigh Scattering Spectra of [CdI4]2--Protein Systems and Their Analytical ApplicationsIn the acid medium solution, proteins such as bovine serum albumin (BSA), human serum albumin (HSA) could react with [CdI4]2- by virtue of electrostatic attraction and hydrophobic force to form ion-association complexes. As a result, the resonance Rayleigh scattering (RRS) intensities were enhanced greatly and new scattering spectra appeared. The maximum scattering peaks of RRS was at 317 nm. The enhanced RRS intensities were directly proportional to the concentrations of proteins. The detection limits for BSA and HSA were 4.9ng/mL,11.3ng/mL. The linear ranges were 0.016-2.5μg/mL,0.038-3.0μg/mL, respectively.In this work, the influences of the interaction of [CdI4]2- with proteins on spectral characteristics of RRS were investigated and the optimum conditions were tested. Meanwhile, the effects of coexisting substances were tested and the results showed that the method exhibited a good selectivity. Based on the above researches, a highly sensitive, simple and rapid method for the determination of trace amounts of proteins by resonance light scattering technique has been developed. It can be applied to the determination of proteins in tablet, human serum and urine samples. 4. Fluorescence Quenching Reaction of Proteins with [HgI4]2- and Its Analytical ApplicationIn the acid medium solution, proteins such as bovine serum albumin (BSA), human serum albumin (HSA) could react with [HgI4]2- by virtue of electrostatic attraction and hydrophobic force to form ion-association complexes, which led to the fluorescence quenching of BSA and HSA. The maximum fluorescence quenching wavelength are at 329 nm and 344 nm respectively. Fluorescence quenching extent (△F) were proportional to the concentration of Hg(Ⅱ) in the range of 0.023 - 1.2μg/mL,0.027-1.2μg/mL respectively, and the detection limits for BSA and HSA were 6.8 ng/mL and 8.2 ng/mL. The effects of some coexisting substances were investigated, and the results showed that the selectivity was good. This method was sensitive, simple and rapid. It could be applied to the determination of Hg(Ⅱ) in environmental water samples with satisfactory results. Based on the above researches, a new method for the determination of trace amounts of Hg(Ⅱ) has been developed.5. Fluorescence Quenching Reaction of BSA with Chrome (Ⅵ)-Iodidesystem and Its Analytical ApplicationIn the acid medium solution, I3- formed by the reaction of of Cr(Ⅵ) with excessive I- could react with bovine serum albumin (BSA) by virtue of electrostatic attraction and hydrophobic force to form ion-association complexes, which led to the fluorescence quenching of BSA. The maximum fluorescence quenching wavelength were at 317 nm. Fluorescence quenching extent (△F) were proportional to the concentration of Cr(Ⅵ) in the range of 0.1-5.0μg/mL, and the detection limit for Cr(Ⅵ) was 29.8 ng/mL.The effects of some coexisting substances were investigated, and the results showed that the selectivity was good. This method was sensitive, simple and rapid. It could be applied to the determination of Cr(Ⅵ) in environmental water samples with satisfactory results. Based on the above researches, a new method for the determination of trace amounts of Cr(Ⅵ) has been developed.
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