Resonance Light Scattering Spectroscopy Research Articles

Optimization of aflatoxin B1 removal efficiency of DNA by resonance light scattering spectroscopy

In this paper, firstly, the resonance light scattering spectra of aflatoxin B1 (AFB1) and DNA were measured by resonance light scattering spectroscopy (RLS), and the DNA binding saturation value (DBSV) of AFB1 was calculated from their spectral results. Then the interaction intensity between DNA and AFB1 and the effects of some external factors on the interaction between DNA and AFB1 were evaluated by corresponding DBSVs, so as to establish and optimize a way for removing AFB1 by DNA. DBSV of AFB1 was 2.04 at 30℃ and pH 7.40. However, after adding sodium ion, calcium ion, vitamin E, vitamin C and D-glucose, DBSV of AFB1 was changed to 2.72, 3.17, 2.67, 1.68 and 1.33 respectively. Correspondingly, the removal efficiency of AFB1 by DNA was changed from 90.05% to 93.25%, 95.48%, 93.08%, 82.36% and 78.90% respectively. These results indicated that the external factors had a significant impact on the interaction between DNA and AFB1. Among them, some factors enhanced the interaction between DNA and AFB1, while some factors weakened the interaction between DNA and AFB1. The change of these external factors led to the corresponding changes in DBSV and the removal efficiency of AFB1. DBSV of AFB1 could really be used as an index to evaluate the intensity of the interaction between DNA and AFB1, and to optimize the removal efficiency of AFB1 by DNA. The experimental data also showed that the adsorption of AFB1 to DNA was consistent with the pseudo-second-order kinetic model and the Freundlich isothermal model, was an exothermic and spontaneous process. All these results will give good references for establishing and optimizing a way of AFB1 removal via DNA intercalation.

Simple and Sensitive Detection of Persulfate Based on a Resonance Light Scattering Spectroscopy

Simple and Sensitive Detection of Persulfate Based on a Resonance Light Scattering Spectroscopy

Complexation behaviors of hyperbranched cationic glycogen derivatives with plasmid DNA revealed by resonance light scattering and circular dichroism spectroscopy

A series of hyperbranched glycogen derivatives conjugated with different contents of cationic 3‐(dimethylamino)‐1‐propylamine residues, named DMAPA‐Glyp derivatives, were synthesized at room temperature. Resonance light scattering (RLS) spectroscopy was used to investigate the complexation behavior and efficacy of the DMAPA‐Glyp derivatives and plasmid DNA (pDNA). Results indicated that the DMAPA‐Glyp derivatives and pDNA molecules began to aggregate and form complexes at a weight ratio of 2. Following further increases in the DMAPA‐Glyp derivatives (w/w >2), pDNA was condensed to form compact complexes. RLS spectroscopy is thus a useful tool for studying the complexation behavior and efficacy of cationic polymers with nucleic acid molecules. Circular dichroism analysis further revealed that the conformation of pDNA transformed from B‐form to C‐form and A‐form during the complexation process.

Evaluation on the Toxic Effects of NanoAg to Catalase.

Protein is the functional actor of life. Research on protein damage induced by nanomaterials may give insight into the toxicity mechanisms of nanoparticles. Studying nano silver over the impact of the structure and function of catalase (CAT) at the molecular level, is of great significance for a comprehensive evaluation of their toxic effects. The toxic effects of nanoAg on catalase were thoroughly investigated using steady state and time resolved fluorescence quenching measurements, ultraviolet-visible absorption spectroscopy, resonance light scattering spectroscopy (RLS), circular dichroism spectroscopy (CD) and transmission electron microscopy (TEM). NanoAg could decrease the amount of alpha-helix and increase the beta sheet structure, leading to loose the skeleton structure of catalase. The characteristic fluorescence of catalase was obviously quenched, which showed the exposal of internal hydrophobic amino acids enhanced, and its quenching type is dynamic quenching. The result of RLS and TEM showed that the distribution and size of nanoAg become more uniform and smaller after their interaction, resulting in a decrease of RLS intensity. NanoAg could make the activity of catalase rise. By changing the structure of catalase, nanoAg increases its enzymatic activity to a certain extent, breaking down its balance in vivo, thereby affecting the normal physiological activities. NanoAg has obvious toxic effects on catalase. This paper provided a new perspective and method for the toxic effects of nanoAg to biological macromolecules; provided basic data and reference gist for the hygienics and toxicology studies of nanoAg. It is conducive to the toxicity prevention and control work of nanoAg, promoting nano-technology applied to human production and living better.

Determination of Trace Bi(Ⅲ) in Environmental Water Samples with Alizarin Red-Bi(Ⅲ)-CTMAB System by Resonance Light Scattering Spectroscopy

In hydrochloric acid solution with pH=4.1,Bi(Ⅲ) can react with alizarin red(AR) and cetyltrimethylammonium bromide(CTMAB) to form ternary ion-association complexe particles(the combination proportion was defined as n(Bi(Ⅲ)):n(AR) :n(CTMAB)=1:3:3).In this case,the resonance light scattering(RLS) intensities are enhanced greatly.The maximum RLS wavelength locates at 364 nm.The optimal conditions of the reaction,influence factors and the effect of coexisting substances were investigated.In addition,the reaction mechanism of the ternary ion-association complex was discussed.Under the optimal experimental conditions of 2.5 mL 1.0×10-4 mol/L alizarim red and 2.0 mL 1.0×10-4 mol/L CTMAB,the resonance scattering intensity(ΔI364 nm) was linearly related to the concentration of Bi(Ⅲ) in the range of 0～0.384 mg/L with a detection limit of 5.898×10-8 g/L.The method can be applied to the determination of Bi(Ⅲ) in water samples.The result was satisfactory and the recoveries were 99.5%～100.2% at the concentrations ranging from 0.552 to 0.831 μg/L,and the relative standard deviation was less than 2.7%.A sensitive,simple and new resonance light scattering method for determination of trace amount of Bi(Ⅲ) in environment was set up using the alizarin red as a spectrum probe.

Aggregation behavior of tetrakis(N, N′, N″, N‴-tetramethyl tetra-2,3-pyridino)porphyrazine copper(II) and its interaction with ct-DNA: a thermodynamic approach

The association behavior of tetrakis( N , N ′, N ″, N ‴-tetramethyl tetra-2,3-pyridino)porphyrazine copper(II) ([ Cu(II) 2,3- tmtppa ]4+) was investigated in aqueous solutions at 25 °C and various ionic strengths using optical absorption and resonance light scattering (RLS) spectroscopies. The results show that ([ Cu(II) 2,3- tmtppa ]4+) does not have any affinity for aggregation due to increasing of salt concentration and exists as monomers even in homogeneous aqueous solutions of high ionic strengths (more than 1 M NaCl ). Interaction of ([ Cu(II) 2,3- tmtppa ]4+) with calf thymus DNA has also been studied in 1 mM aqueous phosphate buffer of pH 7.0, by optical absorption and RLS spectroscopies, and thermal denaturation experiments. The appearance of hypochromicity of less than 10% and bathochromicity shift of Δλ ≤ 2 nm in UV-vis spectra of ([ Cu(II) 2,3- tmtppa ]4+), increasing of thermal melting point of DNA, and no change in RLS spectra of porphyrazine due to interaction with DNA, represent the minor outside groove binding mode without any stack aggregate formation. The thermodynamic of the binding of ([ Cu(II) 2,3- tmtppa ]4+)-DNA also has been studied. The binding constant (K) was obtained by analysis of the optical absorption spectra of the complex at various DNA concentrations using SQUAD software. The value of K was estimated to be 2.34 × 105 ± 0.06 M -1 at 25 °C. The thermodynamic parameters were calculated by van't Hoff equation. The enthalpy and entropy changes were 41.83 ± 3.28 kJ/mol and 242.08 ± 9.88 J/mol.K at 25 °C, respectively. The results indicate that the process is entropy-driven and suggest that hydrophobic interactions are the main driving forces for the complex formation. Increasing of the ionic strength due to addition of NaCl destabilized porphyrazine-DNA complexes, indicating the competition of Na + ions with porphyrazine complexes for occupation of minor groove binding sites.

Interaction Between Isoquercitrin and Bovine Serum Albumin by a Multispectroscopic Method

ABSTRACT The interaction of isoquercitrin and bovine serum albumin (BSA) was investigated by means of fluorescence spectroscopy (FS), resonance light scattering spectroscopy (RLS), and ultraviolet spectroscopy (UV). The apparent binding constants (K a) between isoquercitrin and BSA were 5.37 × 105 L mol−1 (293.15 K) and 2.34 × 105 L mol−1 (303.15 K), and the binding site values (n) were 1.18 ± 0.03. According to the Förster theory of non-radiation energy transfer, the binding distances (r) between isoquercitrin and BSA were 1.94 and 1.95 nm at 293.15 K and 303.15 K, respectively. The experimental results showed that the isoquercitrin could be inserted into the BSA, quenching the inner fluorescence by forming the isoquercitrin–BSA complex. The addition of increasing isoquercitrin to BSA solution leads to the gradual enhancement in RLS intensity, exhibiting the formation of the aggregate in solution. It was found that both static quenching and non-radiation energy transfer were the main reasons for the fluorescence quenching. The entropy change and enthalpy change were negative, which indicated that the interaction of isoquercitrin and BSA was driven mainly by van der Waals interactions and hydrogen bonds. The process of binding was a spontaneous process in which Gibbs free energy change was negative.

Studies on the interaction between benzidine and bovine serum albumin by spectroscopic methods

The interaction between bovine serum albumin (BSA) and benzidine (BD) in aqueous solution was investigated by fluorescence spectroscopy, circular dichroism (CD) spectra and UV-Vis spectroscopy, as well as resonance light scattering spectroscopy (RLS). It was proved from fluorescence spectra that the fluorescence quenching of BSA by BD was a result of the formation of BD-BSA complex, and the binding constants (K (a)) were determined according to the modified Stern-Volmer equation. The enthalpy change (DeltaH) and entropy change (DeltaS) were calculated to be -34.11 kJ mol(-1) and -25.89 J mol(-1) K(-1), respectively, which implied that van der Waals force and hydrogen bond played predominant roles in the binding process. The addition of increasing BD to BSA solution caused the gradual enhancement in RLS intensity, exhibiting the forming of the aggregate. Moreover, the competitive experiments of site markers suggested that the binding site of BD to BSA was located in the region of subdomain IIA (sudlow site I). The distance (r) between the donor (BSA) and the acceptor (BD) was 4.44 nm based on the Förster theory of non-radioactive energy transfer. The results of synchronous fluorescence and CD spectra demonstrated the microenvironment and the secondary conformation of BSA were changed.

Evaluation on the toxicity of nanoAg to bovine serum albumin

Measuring protein damage by nanomaterials may give insight into the mechanisms of toxicity of nanomaterials. The toxic effects of nanoAg on bovine serum albumin (BSA) were thoroughly studied using fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy, resonance light scattering spectroscopy (RLS), circular dichroism spectroscopy (CD) and transmission electron microscopy (TEM). NanoAg had obvious toxic effects on BSA: nanoAg could increase the amount of helix and decrease the beta sheet structure, leading to a loosening of the protein skeleton. In the loose structure, internal hydrophobic amino acids are exposed and the characteristic fluorescence of BSA is obviously quenched. When the ratio of nanoAg and BSA increased to 1: 96 (wt/wt), the impact of nanoAg on the spectral properties leveled off. The RLS spectrum, TEM, CD spectra and electrophoresis results showed that BSA had destroyed the double-layer structure of nanoAg and covered its surface, generating a BSA-nanoAg complex held together by van der Waals and electrostatic forces. This paper provides a new perspective and method for determining the toxic effects of nanoAg on biological macromolecules.

Preparation and Characterization of Heparin‐Stabilized Gold Nanoparticles

A simple method for preparing gold nanoparticles in aqueous solution has been developed by using glycosaminoglycan‐heparin as reducing and stabilizing agent and HAuCl4 as precursor. The obtained gold nanoparticles were characterized by UV‐vis spectroscopy, resonance light scattering spectroscopy (RLS), transmission electron microscopy (TEM) and electrophoresis technology. The influence of reactant concentration for the preparation of gold nanoparticles was investigated. The results indicated that the gold nanoparticles carried negative charges in the aqueous solution and the size and shape of the gold nanoparticles could be controlled by changing the concentration of the heparin. Moreover, the gold nanoparticles obtained with relatively high concentration of heparin were very stable and had relative narrow size distribution.

Analysis of binding interaction between puerarin and bovine serum albumin by multi-spectroscopic method

The interaction of puerarin and bovine serum albumin (BSA) was investigated by means of fluorescence spectroscopy, resonance light-scattering spectroscopy, infrared spectroscopy, and synchronous fluorescence spectra. The apparent binding constants ( K a) between puerarin and BSA were 1.13 × 10 4 (20 °C), and 1.54 × 10 4 l mol −1 (30 °C), and the binding sites values ( n) were 0.95 ± 0.02. The experimental results showed that the puerarin could be inserted into the BSA, quenching the inner fluorescence by forming the puerarin–BSA complex. The addition of increasing puerarin to BSA solution leads to the gradual decrease in RLS intensity, exhibiting the formation of the aggregate in solution. It was found that both static quenching and non-radiation energy transfer were the main reasons for the fluorescence quenching. The positive entropy change and enthalpy change indicated that the interaction of puerarin and BSA was driven mainly by hydrophobic forces. The process of binding was a spontaneous process in which Gibbs free energy change was negative. The competing binding reaction with BSA between Fe 3+, Cu 2+ and puerarin was investigated. The effect of Fe 3+ and Cu 2+ on the binding of puerarin with BSA is discussed.

Effect of temperature on the metronidazole–BSA interaction: Multi-spectroscopic method

The interaction between metronidazole and bovine serum albumin (BSA) was investigated using fluorescence spectroscopy (FS) and resonance light scattering spectroscopy (RLS). The apparent binding constants ( K a) between metronidazole and BSA were 3.42 × 10 4 (20 °C), 5.78 × 10 4 (30 °C) and 8.23 × 10 4 L mol −1 (40 °C), and the binding sites values ( n) were 1.48 ± 0.03. The experimental results showed that the metronidazole could be inserted into the BSA, quenching the inner fluorescence by forming the metronidazole–BSA complex. The addition of increasing metronidazole to BSA solution leads to the gradual enhancement in RLS intensity, exhibiting the formation of the aggregate in solution. It was found that both static quenching and non-radiation energy transfer were the main reasons for the fluorescence quenching. The entropy change and enthalpy change were positive, which indicated that the interaction of metronidazole and BSA was driven mainly by hydrophobic forces. The process of binding was a spontaneous process in which Gibbs free energy change was negative.

Study of the interaction between baicalin and bovine serum albumin by multi-spectroscopic method

The interaction of baicalin and bovine serum albumin (BSA) was investigated using fluorescence spectroscopy (FS), resonance light scattering spectroscopy (RLS), and ultraviolet spectroscopy (UV). The apparent binding constants ( K a) between baicalin and BSA were 1.67 × 10 6 (22 °C), 1.98 × 10 6 (32 °C) and 2.01 × 10 6 (42 °C), and the binding sites values ( n) were 1.33 ± 0.01. According to the Förster theory of nonradiation energy transfer, the binding distances ( r) between baicalin and BSA were 1.94, 1.95 and 1.96 nm at 22, 32, and 42 °C, respectively. The experimental results showed that the baicalin could be inserted into the BSA, quenching the inner fluorescence by forming the baicalin–BSA complex. The addition of increasing baicalin to BSA solution leads to the gradual enhancement in RLS intensity, exhibiting the formation of the aggregate in solution. It was found that both static quenching and non-radiation energy transfer were the main reasons for the fluorescence quenching. The entropy change and enthalpy change were positive, which indicated that the interaction of baicalin and BSA was driven mainly by hydrophobic forces. The process of binding was a spontaneous process in which Gibbs free energy change was negative.

Characterization of Ag/Pt core-shell nanoparticles by UV–vis absorption, resonance light-scattering techniques

The water-soluble Ag/Pt core-shell nanoparticles were prepared by deposition Pt over Ag colloidal seeds with the seed-growth method using K 2PtCl 4 with trisodium citrate as reduced agent. The Ag:Pt ratio is varied from 9:1 to 1:3 for synthesizing Pt shell layer of different thickness. A remarkable shift and broadening of Ag surface plasmon band around 410 nm was observed. The contrast of TEM images of Ag/Pt colloids has been obtained. Various techniques, such as transmission electron microscopy (TEM), UV–vis absorption and resonance light-scattering spectroscopy were used to characterize nanoparticles. The data of TEM, UV–vis and resonance light-scattering spectrum all confirm formation of Ag/Pt core-shell nanoparticles. Resonance light-scattering and emission spectrum show the Ag and Ag/Pt core-shell nanoparticles have a nonlinear light-scattering characteristic.

The interaction of 2-hydroquinone-5,10,15,20-tetra( p-hydroxyphenyl)porphyrin with surfactants: solubilization and J-aggregates

J-aggregates of 2-hydroquinone-5,10,15,20-tetra( p-hydroxyphenyl)porphyrin (HQTHPP) induced by N-lauroyl sarcosine (SKL) in aqueous neutral solutions have been studied by optical absorption, fluorescence, and resonance light-scattering spectroscopies. As SKL concentration increases, the spectra evolve to reveal the presence of four independent species with relative concentration. The most important species is J-aggregates. The J-aggregates have two strong exciton bands corresponding to the B-band and Q-bands of HQTHPP monomers, and are found to be stable when the surfactant concentration is below 8.0 mmol/L. But above 8.0 mmol/L, the J-aggregates dissolve gradually into another species: porphyrin monomers. The total fluorescence of HQTHPP is quenched due to the aggregate formation. A strong and sharply peaked resonance light-scattering signal (>1800 counts/s, centered at 490 nm) is observed just slightly to the red of the J-aggregate absorption maximum. In the case of cetyltrimethyl-ammonium bromide, increasing surfactant concentrations have only shown to favor solubilization of porphyrin monomers. Evidently, the nature of polar headgroups of surfactants influences the tendency of THPP to aggregate.

Resonance light-scattering spectroscopy study on interaction between gold colloid and thiol containing pharmaceutical

In this paper, we used resonance light-scattering (RLS) spectroscopy to study the interaction between thiol-containing pharmaceutical and gold colloid. And for the first time, we proposed that this highly sensitive, gold colloid-based assay using RLS technique may have potential application in detecting thiol-containing substances.

Spectral investigations of the solution properties of 5,10,15,20-tetrakis(4-N-benzyl-pyridyl)porphyrin (TBzPyP) and its interaction with human serum albumin (HSA)

The association behavior of 5,10,15,20-tetrakis(4-N-benzyl-pyridyl)porphyrin ( TBzPyP ) was investigated in aqueous solution at 27 °C and various ionic strengths by optical absorption, fluorescence and resonance light scattering (RLS) spectroscopies. The results show that TBzPyP exists as monomer at low ionic strength and as ill-defined aggregates at high ionic strength and does not show concentration dependent aggregation over an extended concentration range between 5 × 10−7 to 1 × 10−4 M in water. The interaction of the TBzPyP with human serum albumin (HSA) in 5 mM phosphate buffer, pH = 7.00, and at 27 °C, has been also studied by optical absorption, fluorescence and RLS spectroscopies. The formation of two types of complexes (HSA: TBzPyP and (HSA)2: TBzPyP ) has been demonstrated by analysis of optical absorption spectral patterns of TBzPyP at various concentrations of HSA. Based on absorption data, a binding model has been proposed and used to analyze the binding process. The calculated binding constant for formation of HSA: TBzPyP and ( HSA )2: TBzPyP are 3.79 × 106 M−1 and 1.46 × 105 M−1, respectively. The RLS spectra of TBzPyP at various concentration of HSA do not show any aggregation of TBzPyP in the presence of HSA. Due to the fact that binding of TBzPyP quenches the HSA fluorescence, a step-by-step aggregation model, which has been developed by Borissevich, I. E. et al, was used to determine the average aggregation number of HSA, < J >, from the fluorescence quenching. The < J > value is 1.4, which further confirms the formation of the two mentioned complexes at this concentration range of HSA.

A Resonance Light-Scattering Analysis of the Suprahelical Helixes of Nucleic Acids Induced by 5,10,15,20-Tetrakis[4-(trimethyammonio)phenyl]porphine

Abstract This paper discusses the usefulness of resonance light-scattering spectroscopy (RLSS), which can be obtained by using an ordinary spectrofluorimeter, for the analysis of the suprahelical helixes of nucleic acids induced by 5,10,15,20-tetrakis[4-(trimethyammonio)phenyl]porphine (H2tapp). Depending on the acidity of the aqueous solution, the titled porphyrin has two species, [H2tapp]4+ and [H4tapp]6+. Both species can stack on appropriate conditions along the surface of nucleic acids in the mode of long-range assembly; and this leads to the formation of suprahelical helixes of nucleic acids. Enhanced resonance light-scattering signals can be observed for the porphyrin-induced suprahelical helixes of nucleic acids with the maximal resonance light scattering near to 432 nm for [H2tapp]4+ and near to 452 nm for [H4tapp]6+. The exciton splitting signals, which are generally associated with the aggregation of porphyrins, as described by molecular-exciton theory, are observed at 428 nm in the RLS spectra, analogous to the circular dichroism spectra when the molar ratio of [H2tapp]4+ to nucleic acids (R) is greater than 0.89. These results indicate that porphyrin–porphyrin interactions occur in the suprahelical helixes of nucleic acids.

Microdetermination of Proteins by Resonance Light Scattering Spectroscopy with Bromophenol Blue

Reaction of bromophenol blue with proteins results in an enhanced resonance light scattering at 334 nm. Based on this, a new quantitative determination method for proteins in the aqueous solution is established. This assay is characterized by high sensitivity (0.34–18.7 μg/ml), short reaction time (>2 min), and simplicity (a one-step assay). Due to protein-to-protein variability, this method gave results higher than that of the bromocresol green assay in detection of human serum albumin.