Resonance Light Scattering Enhancement Research Articles

Sensitive determination of DNA by RLS enhancement of metal ions

The interactions between metal ions and DNA have been studied by the resonance light scattering (RLS) spectra. In the acidic condition, the RLS signals of metal ions, especially the transition metal ions in group IB and IIB, were increased by DNA. And it is found that the enhancement of RLS signals is linear to the concentration of DNA, so the RLS method for DNA determination was proposed in the presence of Cu2+. On the optimum conditions, the linear range and the detect limit of ctDNA is 4×10−8–4×10−6 g· mL−1 and 1. 13×10−8 g·mL−1, respectively. The proposed method is successfully applied to determine the extracted plasmid DNA ofBacillus subtilis DB104.

Study on the interaction between nucleic acids and cationic surfactants

The interactions of nucleic acids and cationic surfactants (cetylpyridine bromide (CPB) and cetyltrimethylammonium bromide (CTMAB)) in aqueous solution have been studied using the techniques of resonance light scattering (RLS) spectroscopy, the absorption spectroscopy, zeta potential assay and NMR assignment measurement. It is considered that CPB or CTMAB can assemble on the surface of nucleic acid via electrostatic and hydrophobic forces, which results in the formation of large associate of nucleic acid-cationic surfactant and RLS enhancement of nucleic acid. Besides these forces, the π–π stacking force between CPB and nucleic acid also exists in the associate. In comparison with CTMAB, CPB has larger enhancement on RLS of nucleic acid, which is attributed to that the enhancement of the former is only due to the absorption of the bases of nucleic acid, while the enhancement of the latter is own to the synergetic resonance caused by the absorption of both bases of nucleic acid and the pyridyl in CPB. These results have important implication for understanding the influence of surfactants on nucleic acid functionality in life science.

Determination of γ-globulin at nanogram levels by its enhancement effect on the resonance light scattering of functionalized HgS nanoparticles

A novel assay of γ-globulin (γ-IgG) with a sensitivity at the nanogram level is proposed based on the measurement of enhanced resonance light-scattering (RLS) signals resulting from the interaction of functionalized nano-HgS with γ-globulin. At pH 5.03, the RLS signals of functionalized nano-HgS were greatly enhanced by γ-globulin in the region of 200–700 nm characterized by the peak around 362 nm. Linear relationship can be established between the enhanced RLS intensity and γ-globulin concentration in the range of 10–140 ng ml −1. The limit of detection is 2.71 ng ml −1. Based on this, a new direct quantitative determination method for γ-globulin in blood serum samples without separation of human serum albumin (HSA) is established. The contents of γ-IgG in blood serum samples were determined with recovery of 95.7–102.5% and R.S.D. of 1.6–2.4%. This method is proved to be very sensitive, rapid, simple and tolerance of most interfering substances.

Determination of Nucleic Acid at Nanogram Levels with Manganese-Tetrasulfonatophthalocyanine Sensitized by Cetyltrimethylammonium Bromide Using a Resonance Light-Scattering Technique

This is the first report on the determination of deoxyribonucleic acids based on the enhancement of resonance light-scattering (RLS) of manganese-tetrasulfonatophthalocyanine (MnTSPc) by DNA and cetyltrimethylammonium bromide (CTMAB). Under the conditions of pH 10.60∼11.85 and an ionic strength of 0.01 mol L−1 (NaCl), the interaction of MnTSPc with DNA sensitized by CTMAB results in enhanced RLS signals at 314 nm, 346.2 nm, 452.6 nm and 494.4 nm in the enhanced regions. It was found that the enhanced RLS intensity at 346.2 nm was proportional to the concentration of DNA in the suitable ranges. The limits of detection were 11.3 ng mL−1 for fsDNA and 22.9 ng mL−1 for ctDNA when the concentration of MnTSPc was chosen to be 2.0×10−6 mol L−1. This method was simple, rapid, and the dye (MnTSPc) was easily synthetized, inexpensive, and stable. We applied it to the determination of DNA in synthetic samples with satisfactory results.

DETERMINATION OF TOTAL PROTEIN CONTENT IN HUMAN SERUM SAMPLES WITH FAST RED VR BY RESONANCE LIGHT SCATTERING TECHNIQUE

ABSTRACT In an acidic medium, the interaction of Fast red VR (FRV) with proteins such as bovine serum albumin (BSA), human serum albumin (HSA), pepsin (Pep), α-chymotrypsin (Chy), and lysozyme (Lys) was characterized by measuring enhanced resonance light-scattering (RLS) signals. It was found that the enhanced RLS intensities of FRV by proteins at 287.0 nm were in proportion to the concentrations of proteins above, and the limits of determination for BSA, HSA, Lys, γ-IgG were below 25 ng/mL. The present method was successfully applied to the determinations of proteins in synthetic samples, and the total content of proteins in human blood plasma samples, respectively.

DETERMINATION OF NUCLEIC ACIDS AT NANOGRAM LEVELS BY THE METHOD OF RESONANCE LIGHT SCATTERING ON NIGHT BLUE

ABSTRACT A new quantitative determination method at nanogram levels for nucleic acids in aqueous solutions, based on the enhancement of Resonance Light-Scattering (RLS) of Night Blue (NB) by nucleic acids, has been established. The detection limits for calf thymus DNA and yeast RNA is as little as 1.8 and 2.2 ng ml−1, respectively. In addition to its high sensitivity, this method have other advantages: wide pH range (4.5–7.0), rapid reaction (within 10 s), stable mixtures formed (more than 2 days), simple operation (one-step assay), little interference from proteins, nucleosides and most metal ions. The maximum enhanced RLS signal is near 400 nm and 550 nm. The enhanced RLS is proportional to the concentration of nucleic acids in the range of 0–1.2 µg ml−1 for calf thymus (ctDNA) and 0–2.5 µg ml−1 for yeast RNA (yRNA). Four synthetic and real samples were determined with satisfaction results.

A Resonance Light-Scattering Determination of Proteins with Fast Green FCF

The interaction of Fast Green FCF (FCF) with proteins (including bovine serum albumin (BSA), human serum albumin (HSA), pepsin (Pep) and alpha-chymotrypsin (Chy), and lysozyme (Lys)) was characterized by enhanced resonance light-scattering (RLS) measurements using a common spectrofluorometer. The enhanced RLS signals of FCF by proteins at 279.0 nm were obtained, and the mechanism of the RLS enhancement was considered in terms of the effects of the pH and ionic strength on the interaction. It was found that the enhanced RLS intensities were in proportion to the concentrations of proteins in the range of nanogram levels, displaying that the present assay is much more sensitive than the reported RLS methods, with the limits of determination being 4.54, 0.6, 22.8, 4.32 and 1.75 ng/ml for BSA, HSA, Pep, Chy, and Lys. respectively.

Study of the interaction of nucleic acids with acridine red and CTMAB by a resonance light scattering technique and determination of nucleic acids at nanogram levels

In this paper, a determinating method of nucleic acids at nanogram levels by a resonance light scattering (RLS) technique with a common spectrofluorometer has been reported. The characteristics of RLS spectra of acridine red (AR) with nucleic acids, the effective factors and the optimum conditions have been studied. In the pH range 6.40–7.10, nucleic acids and surfactant CTMAB can jointly enhance the intensity of resonance light scattering of AR and the interaction of AR with nucleic acids results in three characteristic peaks of RLS at 410, 470 and 555 nm. Mechanistic studies shows that when the molar ratio of nucleic acids to AR ( m) is smaller than 5:1, the assembly of AR on the molecular surface of nucleic acids occurs and the enhancement of RLS can be observed. The binding numbers resulting from the Scatchard plot are increased in the presence of CTMAB. When m is higher than 5:1, AR intercalates into the base pairs of DNA. The enhanced intensity of RLS is in proportion to the concentration of nucleic acids in the range 5.0×10 −8 to 8.0×10 −6 g ml −1 for yeast RNA, 5.0×10 −9 to 5.0×10 −6 g ml −1 for fish sperm DNA and 5.0×10 −8 to 1.2×10 −6 g ml −1 for calf thymus DNA. The limits of detection are 1.28, 0.095 and 8.53 ng ml −1, respectively. Synthetic samples were determined satisfactorily. Especially, the detection limit of fish sperm DNA has reached 10 −11 g ml −1. It shows that this method has high sensitivity.

Determination of Albumin and Globulin at Nanogram Levels by a Resonance Light-Scattering Technique with α,β, γ, δ-Tetrakis(4-sulfophenyl)porphine

A method for determination of bovine serum albumin (BSA) and γ-globulin (γ-IgG) at nanogram levels is proposed by using a common spectrofluorometer to detect the intensity of resonance light-scattering. In the presence of BSA or γ-IgG at pH 1.86 and ionic strength 0.04, the aggregation of α,β,γ,δ-tetrakis(4-sulfophenyl)porphine (TPPS4) was observed. It was found to result in strong enhanced resonance light-scattering (RLS) signal with a scattering peak at 490.0 nm. But at pH 1.86 and ionic strength 0.11, only BSA can induce the aggregation of TPPS4 resulting in the strong enhanced RLS. Determination for synthetic samples by making use of the effect of ionic strength showed that if the ratio of γ-IgG in the mixture of γ-IgG and BSA is lower than 0.20, the results for the simultaneous determination of BSA and γ-IgG fractions without separation are satisfactory, but if the content of γ-IgG in the mixture is too high, the determination error is significant. However, the total content of BSA and γ-IgG in human serum can be determined with results identical to those obtained according to the Bradford method using CBB G-250.

Determination of nucleic acids by a resonance light-scattering technique with alpha, beta, gamma, delta-tetrakis[4-(trimethylammoniumyl)phenyl]porphine.

The resonance light-scattering technique, using a spectrofluorometer, was first developed as a sensitive instrumental analysis method. At pH 7.48 and ionic strength 0.004, the extent of light-scattering of alpha, beta, gamma, delta-tetrakis[4-(trimethylammoniumyl)phenyl]porphine (TAPP) is enhanced by nucleic acids near 432 nm. There are linear relationships between the enhanced extents of light-scattering and the concentrations of nucleic acids in the range of 1.8 x 10(-7)-10.8 x 10(-7) M for calf thymus and fish sperm DNA and in the range of 1.8 x 10(-7)-1.8 x 10(-6) M for yeast RNA. The limit of determination (3 sigma) is 4.1 x 10(-8) M for calf thymus DNA, 4.6 x 10(-8) M for fish sperm DNA, and 6.7 x 10(-8) M for yeast RNA. Mechanism study indicates that nucleic acids react with the title porphyrin in two modes, depending on the concentrations of nucleic acids. When the molar ratio of nucleic acids to TAPP is smaller than 4:1, the hypochromicity and fluorescence quenching of TAPP by nucleic acids appear, and the enhancement of resonance light-scattering can be observed. When the molar ratio of nucleic acids to TAPP is larger than 4:1, a new fluorescent complex is formed.