Rayleigh light scattering study on the reaction of nucleic acids and methyl violet

A new method for the determination of nucleic acid using an Eu3+- nicotinic acid complex as a resonance light scattering probe

This study found that in Tris-HCl buffer, the resonance light scattering (RLS) intensity of the Eu³⁺-nicotinic acid system can be greatly enhanced by nucleic acids and the enhanced intensity is proportional to the concentration of nucleic acid in the range of 7×10^-8-1×10^-5 g∙mL^-1 for fsDNA, and its detection limit is 2×10^-8 g∙mL^-1. Based on this, a new method for the determination of nucleic acids is proposed. Synthetic and actual samples are determined satisfactorily. The interaction mechanism is also studied. It is thought that nucleic acid can bind with the Eu³⁺-nicotinic acid complex through electrostatic attraction and thus form a large Eu³⁺-nicotinic acid-nucleic acid complex.

Spectral studies on the interaction of acid chrome blue K with nucleic acids in the presence of cetyltrimethylammonium bromide and the confirmation of combined points

The interaction of Acid chrome blue K (ACBK) with nucleic acids in weak basic medium was studied in the presence of cetyltrimethylammonium bromide (CTMAB) based on the measurements of resonance light scattering (RLS), UV-vis, NMR spectra, etc. In hexamethylene tetramine (HMTA) buffer (pH 7.45), ACBK and nucleic acids react with CTMAB to form a ternary complex, which results in strong enhanced RLS signals characterized by four peaks at 285, 335, 405.5 and 548nm. Mechanistic studies show that the enhanced RLS stems from the aggregation of ACBK on nucleic acids through the bridged and synergistic effect of CTMAB. With the enhanced RLS signals at the best wavelength at 335nm, the enhanced RLS intensity is proportional to the concentration of nucleic acids in a wide range. The lowest limit of determination was 7.52ngml(-1), three synthetic samples were analyzed satisfactorily. And the combined points of the anionic dye ACBK with nucleic acids-CTMAB have been tentatively confirmed through the measurement of 1H NMR spectra.

A novel and sensitive method for recognition and indirect determination of Al(III) in biological fluid based on the quenching of resonance Rayleigh scattering intensities of "Al(III)-EV-DNA" complexing system

A novel method for recognition and indirect determination of Al(III) by using biological molecules has been established based on the quenching of RRS intensity. In the weak acidic medium, the reaction of ethyl violet (EV) and DNA would result in great enhancement of RRS intensity. However, the presence of Al(III) would lead to the decrease of the RRS intensity owing to the competition coordination of Al with DNA. The decreased intensity of RRS is directly proportional to the concentration of Al(III) in the range of (0.1-2.5)x10(-6) and (0.30-4.5)x10(-5)M, respectively. The method has high sensitivity and its detection limit (3sigma) is 3.6x10(-8)M. The characteristics of RRS spectra of the system, the optimum conditions of the reaction, and the reaction mechanism have been investigated. The method can recognize Al(III) selectively owing to its strong binding to the phosphate backbone of DNA, and has been applied to the determination of Al(III) concentration in synthetic biological samples with satisfactory results. Therefore, the proposed method is promising as an effective means for selective recognition and sensitive determination in situ of Al(III). Furthermore, this study would contribute to further understanding of the biological significance of Al neurotoxicity.

Nucleic Acids Analysis with Nano-Ag-Tb(III) by a Resonance Light Scattering Technique

The nano-Ag-terbium(III)-mucleic acids system was observed by a resonance light scattering (RLS) technique for the first time, and the quantitative analysis of nucleic acids at nanogram levels was established. Studies showed that the RLS intensity of the nano-Ag-terbium(III) system can be obviously enhanced by nucleic acid, which was characterized by the RLS spectrum and the UV-Vis spectrum. In this system, the nanoparticles were only of a definite size and in a limited particle concentration region. Further research indicated that under the optimum conditions, the enhanced intensity of RLS is in proportion to the concentration of nucleic acids in the ranges of 7.0 x 10(-9) g ml(-1) to 8.0 x 10(-6) g ml(-1) for calf thymus DNA (ctDNA), 2.0 x 10(-8) g ml(-1) to 1.0 x 10(-6) g ml(-1) for fish sperm DNA (fsDNA) and 1.0 x 10(-9) g ml(-1) to 1.0 x 10(-7) g ml(-1) for yeast RNA (yRNA). The detection limits were 1.4 ng ml(-1) for ctDNA, 1.2 ng ml(-1) for fsDNA and 0.85 ng ml(-1) for yRNA, respectively. Synthetic and real samples were determined satisfactorily.

Study on the interaction between nucleic acid and Eu3+-oxolinic acid and the determination of nucleic acid using the resonance light scattering technique

At pH 9.75, the resonance light scattering (RLS) intensity of OA-Eu3+ system is greatly enhanced by nucleic acid. Based on this phenomenon, a new quantitative method for nucleic acid in aqueous solution has been developed. Under the optimum condition, the enhanced RLS is proportional to the concentration of nucleic acid in the range of 1.0x10(-9) to 1.0x10(-6)g/ml for herring sperm DNA, 8.0x10(-10) to 1.0x10(-6) g/ml for calf thymus DNA and 1.0x10(-9) to 1.0x10(-6) g/ml for yeast RNA, and their detection limits are 0.020, 0.011 and 0.010 ng/ml, respectively. Synthetic samples and actual samples were satisfactorily determined. In addition, the interaction mechanism between nucleic acid and OA-Eu3+ is also investigated.

Study on the resonance light-scattering spectrum of anionic dye xylenol orange-cetyltrimethylammonium-nucleic acids system and determination of nucleic acids at nanogram levels

The interaction of xylenol orange (XO) and nucleic acids in the presence of cetyltrimethylammonium bromide (CTMAB) in aqueous solution has been studied by a resonance light-scattering (RLS) technique with a common spectrofluorometer. In hexamethylenetetramine (HMTA) buffer (pH7.30), XO and nucleic acids react with cetyltrimethylammonium bromide to form large particles of three-component complex, which results in strong enhanced RLS signals characterized by three peaks at 295.9, 335.5 and 542 nm, Mechanistic studies showed that the enhanced RLS stems from the aggregation of XO on DNA through the bridged and synergistic effect of CTMAB. With the enhanced RLS signals at the three wavelengths, the enhanced RLS intensity is proportional to the concentration of nucleic acids in an appropriate range. The lowest limit of determination was 5.31 ng ml(-1), three synthetic samples of yDNA were analyzed satisfactorily.

Study on bromocresol green-cetyltrimethylammonium-deoxyribonucleic acids system by resonance light scattering spectrum methods

An assay of deoxyribonucleic acids (DNA) determination, with the sensitivity at nanogram level, was established in the present study by using a common spectrofluorometer to detect the intensity of resonance light scattering (RLS). In hexamethylene tetramine (HMTA) buffer (pH 11.00), Bromocresol Green (BCG) and deoxyribonucleic acids (DNA) react with cetyltrimethylammonium bromide (CTMAB) to form large particles of three-component complex, which results in strong enhanced RLS signals characterized by three peaks at 336, 390, and 622 nm and at 336 nm that is the strongest of the three enhanced RLS peaks. Mechanistic studies showed that the enhanced RLS stems from the aggregation of BCG on DNA through the bridged and synergistic effect of CTMAB. Yeast DNA (yDNA), in the range of 0.05-0.90 ngml(-1), fish sperm DNA (fsDNA) in the range of 0.05-0.80 ngml(-1), and calf thymus DNA (ctDNA) in the range of 0.05-0.80 ngml(-1) can be determined if 2.0 x 10(-6) moll(-1) BCG was employed. The determination limit of yDNA was 12.7 ngml(-1). Three synthetic samples of yDNA were analyzed with good reproducibility.

Pharmacokinetic detection of penicillin excreted in urine using a totally internally reflected resonance light scattering technique with cetyltrimethylammonium bromide

A quantitative analysis method for penicillins including ampicillin (AmP), benzyl penicillin (BP), oxacillin (OA) and amoxycillin (AmO) is proposed that makes use of the totally internally reflected resonance light scattering (TIR-RLS) signal from the penicillin at the H2O/CCl4 interface in the presence of cetyltrimethylammonium bromide (CTMAB), and enables the pharmacokinetics of penicillin taken orally and excreted through urine to be monitored. Penicillin is coadsorbed with CTMAB at the H2O/CCl4 interface in neutral solution, resulting in the formation of ion associates that display greatly enhanced TIR-RLS signals (maximum at 368-372 nm). This enhanced TIR-RLS intensity was found to be proportional to the penicillin concentration over the range 0.2 x 10(-6) to 2.2 x 10(-6) mol L(-1), with limits of determination (3sigma) of 5.0 x 10(-8) to 7.0 x 10(-8) mol L(-1). Pharmacokinetics studies performed using the present method show that the excretion of orally-taken ampicillin through urine has a half-time of 1.05 h and an excremental quantum over 8 h of 49.3%, respectively.

Determination of nucleic acids at nanogram level using resonance light scattering technique with Congo Red

Based on the enhancement of the resonance light scattering (RLS) of Congo Red (CR) by nucleic acid, a new quantitative method for nucleic acid is developed. In the Tris-HCl buffer (pH 10.5), the weak light scattering of CR is greatly enhanced by addition of nucleic acid and CTMAB, the maximum peak is at 560 nm and the enhanced intensity of RLS is in proportion to the concentration of nucleic acid. The linear range is 1.0 x 10(-9) to 1.0 x 10(-6) g ml(-1), 7.5 x 10(-8) to 1.0 x 10(-6) g ml(-1) and 7.5 x 10(-8) to 2.5 x 10(-6) g ml(-1) for herring sperm DNA, calf thymus DNA and yeast RNA, and the detection limits are 0.019, 0.89 and 1.2 ng ml(-1) (S/N = 3), respectively. Actual biological samples were satisfactorily determined.