Resonance Light Scattering Research Articles

Spectroscopic Studies on the Interaction of a Water-Soluble Cationic Porphyrin with Bovine Serum Albumin

The interaction of a water-soluble cationic porphyrin, Cobalt(III) 5, 10, 15, 20-tetrakis (1-methylpyridinium-4-yl) porphyrin [Co(III)TMPyP], with bovine serum albumin (BSA) has been studied in 1 mM phosphate buffer pH 7.0 containing 5 mM NaCl by UV-vis absorption, resonance light scattering (RLS) and fluorescence spectroscopies at 25°C. The results of RLS studies represent no aggregate formation of porphyrin in the surface of BSA and low tendency of this porphyrin for aggregate formation.The binding of porphyrin complex to BSA quenches fluorescence emission of BSA via a dynamic mechanism and the quenching process obeys a linear Stern-Volmer relationship. The values of Stern-Volmer constants, KSV, was determined nearly 105M−1, that depend on BSA concentration. The average aggregation number of BSA calculated from the analysis of fluorescence quenching data indicates that absence of any porphyrin induced aggregation of BSA due to its interaction with porphyrin complex. The binding of Co(III) TMPyP had no obvious effect on the molecular conformation of the protein. Electrostatic force played an important role in the binding due to the opposite charges on porphyrin and the protein.

Spectroscopic studies on the interaction of a water-soluble cationic porphyrin with bovine serum albumin.

The interaction of a water-soluble cationic porphyrin, Cobalt(III) 5, 10, 15, 20-tetrakis (1-methylpyridinium-4-yl) porphyrin [Co(III)TMPyP], with bovine serum albumin (BSA) has been studied in 1 mM phosphate buffer pH 7.0 containing 5 mM NaCl by UV-vis absorption, resonance light scattering (RLS) and fluorescence spectroscopies at 25°C. The results of RLS studies represent no aggregate formation of porphyrin in the surface of BSA and low tendency of this porphyrin for aggregate formation.The binding of porphyrin complex to BSA quenches fluorescence emission of BSA via a dynamic mechanism and the quenching process obeys a linear Stern-Volmer relationship. The values of Stern-Volmer constants, KSV, was determined nearly 105 M−1, that depend on BSA concentration. The average aggregation number of BSA calculated from the analysis of fluorescence quenching data indicates that absence of any porphyrin induced aggregation of BSA due to its interaction with porphyrin complex. The binding of Co(III) TMPyP had no obvious effect on the molecular conformation of the protein. Electrostatic force played an important role in the binding due to the opposite charges on porphyrin and the protein.

Resonance light scattering method for the detection of peanut allergen-Ara h 1 using gold nanorods prepared by improved synthesis through the use of a sodium dodecyl benzene sulfonate additive

Peanut allergen is a growing food safety problem because peanut seeds are increasingly used in the food industry. Here we report a resonance light scattering (RLS) method for the detection of peanut allergen-Ara h 1 with gold nanorods (GNRs) prepared by an improved synthesis through the use of an anionic surfactant sodium dodecyl benzene sulfonate (SDBS) additive. The study demonstrated that the use of SDBS allows the reduction of hexadecyltrimethylammonium bromide to 0.05 M as opposed to 0.1 M in well-established protocols, and improves the monodispersity and stability of the GNRs. Moreover, a probe DNA modified with a thiol at its 5′ end and a biotin at its 3′ end was attached to the surface of the as-synthesized GNRs to form a stem–loop structure by self-assembly through facile gold–thiol affinity. The stem–loop probe was “closed” when the target DNA was absent; however, the hybridization of the target DNA with the probe DNA induces the conformational change to “open”, along with the biotin at its 3′ end moving away from the GNR surface, which results in an increase of the RLS intensity of the GNRs. The detection limit was found to be 0.06 pM with the linear response ranging from 0.0002 to 50 nM. The present method offers the improvement of rapidity, sensitivity and selectivity compared with other reported methods. It has been successfully applied for the determination of peanut allergen-Ara h 1 in peanut milk beverage.

Assessment of Potential Toxicity of Alizarin Through Resonance Light Scattering

Assessment of Potential Toxicity of Alizarin Through Resonance Light Scattering

Quantitative Detection of Proteins by [Co(NH3)6]3+-DNA Probe of Resonance Light Scattering Technique

[Co(NH3)(6)](3+)-DNA complex produces strong electrical force with proteins, which results in strong enhancement of resonance light scattering intensity. Resonance light scattering intensity at 346 nm was proportional to the concentration of bovine serum albumin in the range of 0.05-1.3 mu g/mL. The limit of determination for bovine serum albumin has obtained at nanogram level. The method is applied to the assay of bovine serum albumin and good results have been obtained compared with custom measure methods. A sensitive, accurate and convenient new analysis method for micro-determination of proteins is established.

A microarray-based resonance light scattering assay for detecting thrombin generation in human plasma by gold nanoparticle probes

A peptide microarray-based resonance light scattering (RLS) assay with gold nanoparticle probes has been developed for monitoring thrombin generation in human plasma. Thrombophilia, hypocoagulability and normal plasma have been successfully differentiated by the assay.

Investigation on the Interaction Between Anthracyclines and DNA in the Presence of Quercetin by Resonance Light Scattering Technique and Its Analytical Application

Investigation on the Interaction Between Anthracyclines and DNA in the Presence of Quercetin by Resonance Light Scattering Technique and Its Analytical Application

Determination of Human Serum Albumin with Tetra-amino Copper Phthalocyanine by Resonance Light Scattering Technique

Determination of Human Serum Albumin with Tetra-amino Copper Phthalocyanine by Resonance Light Scattering Technique

Localized surface plasmon resonance light-scattering detection of Hg(ii) with 3-aminopropyltriethoxysilane-assisted synthesis of highly stabilized Ag nanoclusters

We employed 3-aminopropyltriethoxysilane to assist the synthesis of Ag NCs using polyethyleneimine as the template for detecting Hg(2+) by localized surface plasmon resonance light-scattering technology. The developed selective and sensitive method presaged more opportunities for application in environmental systems.

High-performance liquid chromatography assay of cysteine and homocysteine using fluorosurfactant-functionalized gold nanoparticles as postcolumn resonance light scattering reagents

Herein, a new postcolumn resonance light scattering (RLS) detection approach coupled with high-performance liquid chromatography (HPLC) was developed to detect cysteine and homocysteine. In the established system, the fluorosurfactant-capped gold nanoparticles (AuNPs) were first employed as postcolumn RLS reagents. The detection principle was based on the enhancement of RLS intensity of AuNPs upon the addition of cysteine/homocysteine. The RLS signals were detected by a common fluorescence detector at λEX=λEM=560nm. The linear ranges for both cysteine and homocysteine were in the range of 5.0–50μM. The detection limits were 5.9pmol for cysteine and 12pmol for homocysteine at a signal-to-noise ratio of 3. HPLC separation and RLS detection conditions were optimized in detail. The applicability of the proposed method has been validated by detecting cysteine and homocysteine in human urine samples. Recoveries from spiked urine samples were 95.0–103.0%.

Investigation on the Interaction Between Anthracyclines and DNA in the Presence of Quercetin by Resonance Light Scattering Technique and Its Analytical Application

Resonance light scattering technique has been employed to investigate the interaction between anthracyclines and DNA in the presence of quercetin. Upon binding to DNA, anthracyclines undergo dramatic enhancement in their resonance light scattering intensities, while quercetin goes through no obvious change in its intensity. Once being added into anthracyclines- DNA system, quercetin can induce great difference in resonance light scattering intensities between anthracyclines- DNA-quercetin ternary system and anthracyclines-DNA binary system. Consequently, the DNA binding abilities of anthracyclines can be improved by quercetin. Improved efficiency of quercetin on the interaction between anthracyclines and DNA has been calculated. Under the experimental condition, the improved efficiency values of doxorubicin, epirubicin and mitoxantrone were 38.78%, 28.53% and 16.69%, respectively. Additionally, the weak resonance light scattering intensity of quercetin-DNA system is greatly enhanced by anthracyclines and the enhanced intensity is proportional to the concentration of anthracyclines in the range 0.06-9.0 μg mL-1 for doxorubicin, 0.08-12 μg mL-1 for epirubicin and 0.01-3.0 μg mL-1 for mitoxantrone. The detection limits are 4.7 ng mL-1 for doxorubicin, 5.4 ng mL-1 for epirubicin and 1.4 ng mL-1 for mitoxantrone.

Multimodal optical microscopy in combination with gold nanorods for cancer cell imaging

The multimodal optical imaging technique, which utilizes nonlinear and linear optical processes, plays an important role in biological and biomedical research. As second-order nonlinear phenomenon, the two-photon luminescence (TPL) results from the nonlinear excitation of fluorescent molecules, while the second harmonic generation (SHG) depends on the second order nonlinear polarization, orientation, and noncentrosymmetric properties of molecules. In contrast, the linear resonance light scattering (RLS) occurs when the molecules are excited by a light beam with a wavelength close to their absorption bands. Since SHG, TPL, and RLS involve different kinds of optical processes, they might be used in parallel to provide complementary information about the structure and function of cells and tissues. Herein, we develop for the first time a multimodal optical microscopy with the capability of simultaneous SHG, TPL, and RLS imaging. We analyze theoretically and demonstrate experimentally the near-infrared irradiation-induced SHG, TPL, and RLS from the gold nanorods with nanometer spatial resolution. With the gold nanorods as the contrast agents, we further demonstrate the simultaneous SHG, TPL, and RLS imaging of A431 human epithelial skin cancer cells. This multimodal optical microscopy might provide a reliable and complementary approach for biological and biomedical research.

Investigation on the Interaction Between Anthracyclines and DNA in the Presence of Quercetin by Resonance Light Scattering Technique and Its Analytical Application

Resonance light scattering technique has been employed to investigate the interaction between anthracyclines and DNA in the presence of quercetin. Upon binding to DNA, anthracyclines undergo dramatic enhancement in their resonance light scattering intensities, while quercetin goes through no obvious change in its intensity. Once being added into anthracyclines- DNA system, quercetin can induce great difference in resonance light scattering intensities between anthracyclines- DNA-quercetin ternary system and anthracyclines-DNA binary system. Consequently, the DNA binding abilities of anthracyclines can be improved by quercetin. Improved efficiency of quercetin on the interaction between anthracyclines and DNA has been calculated. Under the experimental condition, the improved efficiency values of doxorubicin, epirubicin and mitoxantrone were 38.78%, 28.53% and 16.69%, respectively. Additionally, the weak resonance light scattering intensity of quercetin-DNA system is greatly enhanced by anthracyclines and the enhanced intensity is proportional to the concentration of anthracyclines in the range 0.06-9.0 μg mL-1 for doxorubicin, 0.08-12 μg mL-1 for epirubicin and 0.01-3.0 μg mL-1 for mitoxantrone. The detection limits are 4.7 ng mL-1 for doxorubicin, 5.4 ng mL-1 for epirubicin and 1.4 ng mL-1 for mitoxantrone. Keywords: Circular dichroism spectroscopy, DNA, Detection, Doxorubicin, Epirubicin, Interaction, Mitoxantrone, Quercetin, Resonance light scattering, Ultraviolet visible spectroscopy

Probing the interaction of human serum albumin with vitamin B2 (riboflavin) and l-Arginine (l-Arg) using multi-spectroscopic, molecular modeling and zeta potential techniques

This study was designed to examine the interaction of Riboflavin (RB) and l-Arginine (l-Arg) with human serum albumin (HSA) using different spectroscopic, zeta potential and molecular modeling techniques under imitated physiological conditions. The resonance light scattering (RLS) method determined the critical aggregation concentration of RB on HSA in the presence and absence of l-Arg which confirmed the zeta potential results. The binding constants (Ka) of HSA–RB were 2.5×104 and 9.7×103M−1, respectively in binary and ternary system at the excitation wavelength of 280nm, also were 7.5×103 and 7.3×103, respectively in binary and ternary system at the excitation wavelength of 295nm. Fluorescence spectroscopy demonstrated that in the presence of l-Arg, the binding constant of HSA–RB was increased. Static quenching was confirmed to results in the fluorescence quenching and FRET. The binding distances between HSA and RB in two- and three-component systems were estimated by the Forster theory which revealed that nonradiative energy transfer from HSA to RB occurred with a high probability. The effect of RB on the conformation of HSA was analyzed using synchronous fluorescence spectroscopy and circular dichroism (CD) in both systems. Docking studies demonstrated a reduction in the binding affinity between RB and HSA in the presence of l-Arg.

Resonance light scattering determination of metallothioneins using levofloxacin−palladium complex as a light scattering probe

A novel method of resonance light scattering (RLS) was developed for the analysis of trace metallothioneins (MTs) in human urine. In a CH3COOH–CH3COONa buffer solution of pH 4.5, the formation of a complex between levofloxacin (LEV)–Pd and MTs led to enhance the RLS intensity of the system, and the enhanced RLS intensity at 468nm was proportional to the concentration of MTs in the range of 0.059–22.4μgmL−1. The linear regression equation was ΔI=127.5 ρ (μgmL−1)–88.02 with a correlation coefficient of 0.9992, and the detection limit of 17.8ngmL−1. The relative standard deviation and the average recovery were 3.8–5.4% (n=11) and 92.15%, respectively. The proposed method is convenient, reliable and sensitive, and has been used successfully for the determination of trace MTs in human urine samples.

Binding Effect of Common Ions to Human Serum Albumin in the Presence of Norfloxacin: Investigation with Spectroscopic and Zeta Potential Approaches

In this work, the toxic influence of metallic ions (Al3+, Cu2+, Mg2+, Pb2+) on human serum albumin (HSA) in the absence and presence of norfloxacin (NRF) was studied by spectroscopic approaches [fluorescence quenching, synchronous fluorescence, three-dimensional fluorescence, circular dichroism, resonance light scattering (RLS) and zeta potential techniques] under simulated physiological conditions. Fluorescence spectroscopy revealed that these metallic ions and NRF can quench the HSA fluorescence, and this quenching effect became more significant when both ion and drug are present together. The binding constants and binding sites of metal ions with HSA in the absence and presence of NRF were determined, based on the fluorescence quenching results. Ion aggregation gives rise to an enhancement of the RLS intensity for HSA and the critical induced aggregation concentration (C CIAC) of the ions, causing HSA aggregation for binary and ternary systems. The zeta potential measurements indicate a combination of electrostatic and hydrophobic interactions between ion, NRF and HSA and the formed micelle-like clusters. These data illustrated that NRF has an effect on the interaction between HSA and metal ions, with relevance for various toxicological and therapeutic processes.

Synthesis, characterisation and properties of star polypseudorotaxanes with cucurbit[7]uril

New star polypseudorotaxanes that include 4,4′-dipyridyl-terminated 4-arm-poly(ethylene glycol) (PC1) and cucurbit[7]uril (CB[7]) were easily synthesised. The 1H NMR, UV–vis and resonance light scattering (RLS) data show that the viologen units of the star polypseudorotaxanes could fall off from the hydrophobic cavity of CB[7] with the addition of 1-adamantylamine (ADA). The cyclic voltammograms results indicate that the star polypseudorotaxanes have the redox property with the addition of ADA compared with the non-redox property of the pure star polypseudorotaxanes. The biological toxicity experiment shows that the bactericidal activity of the star polypseudorotaxanes in Escherichia coli was aroused by adjusting CB[7] dethreading from the star polypseudorotaxanes with the addition of another competitive guest ADA, which has a very high affinity for CB[7].

Immunoassay for serum alpha-fetoprotein using silver nanoparticles and detection via resonance light scattering

The assay for alpha-fetoprotein (AFP) is based on the use of immobilized anti-AFP labeled with silver nanoparticles (AgNPs). The immunoreaction between the labeled antibody against AFP and free AFP takes place in pH 6.0 solution and leads to the formation of the respective immunocomplex which displays enhanced resonance light scattering (RLS) intensity at 480 nm. Under the optimal conditions, the intensity of the enhanced RLS is proportional to the concentration of AFP in the range from 0.10 to 50 ng mL−1, with a detection limit of 40 pg mL−1. The characteristics of RLS, the immunocomplex, the immuno response, and the optimum conditions of the immunoreaction have been investigated. The concentration of AFP in 20 serum specimens was determined by the new assay, and results are consistent with those obtained with a commercially available ELISA kit.

Detection of Vascular Endothelial Growth Factor Based on Gold Nanoparticles and Immunoreaction Using Resonance Light Scattering

In the study, a new assay of vascular endothelial growth factor (VEGF) has been developed by the use of gold nanoparticles (GNPs)–anti-VEGF conjugates. The immunoreaction between GNPs–anti-VEGF conjugates and VEGF took place in pH 7.5 PBS buffer solution after the addition of VEGF. The formation of GNPs modified VEGF immunocomplex resulted in the enhanced resonance light scattering (RLS) intensity at 388.0 nm. Under the optimal conditions, the magnitude of enhanced RLS intensity (ΔI RLS) was proportional to the VEGF concentration in the range from 100 to 1,500 pg mL−1, with a detection limit of 60 pg mL−1. The surface plasma resonance absorption spectrum, the characteristics of RLS, the VEGF immunocomplex, and the optimum conditions of the immunoreaction have all been investigated. The VEGF concentrations of 20 serum specimens detected by the developed assay showed consistent results in comparison with those obtained by commercially available enzyme-linked immunosorbent assay kit.

A highly sensitive label-free resonance light scattering assay of carcinoembryonic antigen based on immune complexes

As a kind of glycoprotein, carcinoembryonic antigen (CEA) is the important tumor marker for clinical diagnosis of the presence or recurrence of cancer. In this work, a novel label-free resonance light scattering (RLS) spectral CEA assay was developed based on the combination of highly selective immunoreaction and ultrasensitive RLS technique. In Tris–HCl buffer solution (pH 7.5), the specific immunoreaction between CEA antigen and mouse anti-CEA formed immune complexes which had a maximum RLS spectral peak at 389.0nm, with the existence of physiological saline and polyethylene glycol 20,000 (PEG 20,000). Under the optimal conditions, the magnitude of enhanced RLS intensity (ΔIRLS) was proportional to the concentration of CEA in the range from 0.1 to 60ngmL−1, with a detection limit (LOD, 3σ) of 0.03ngmL−1. The characteristics of RLS, the CEA immunocomplex, the immune response, the ratio of CEA antigen and mouse anti-CEA, and the optimum conditions of the immunoreaction have been investigated. The CEA concentrations of 20 serum specimens detected by the developed assay showed consistent results in comparison with those obtained by commercially available enzyme-linked immunosorbent assay (ELISA) kit. And this method has many satisfying merits including label-free, sensitivity and high selectivity.