Selective Determination of Rutin by Fluorescence Attenuation of the CdS-2-mercaptopropionic Acid Nanocrystal Probe

A novel multi-purpose enzymatic system and procedures for the rapid fluorescent determination of flavonoids in herbal pharmaceuticals and plant materials

The paper presents a novel multi-purpose enzymatic system and procedures for fluorescent determination of several flavonoids in herbal pharmaceuticals and plant materials after their enzyme-catalyzed oxidation by hydrogen peroxide and further derivatization with meso-1,2-diphenylethylenediamine. This system may be used for rapid (15-30min/20 samples) simultaneous screening of samples containing a certain flavonoid in a standard microplate, or as a HPLC detection system for analyzing plant extracts with uncertain composition. In the first case, this indicator system provides sensitive and reproducible microplate determination of quercetin, epicatechin, caffeic acid, and taxifolin in the ranges 0.1-5, 1-10, 0.1-10, 0.5-5μM, respectively. In the second case, quercetin, epicatechin, and caffeic acid can be determined in the ranges 0.05-0.75, 0.05-0.75, and 0.01-0.75µg/ml (0.16-2.5, 0.17-2.6, 0.06-4.2μM), respectively. We have demonstrated the application of the system for the analysis of 3 pharmaceuticals and 3 types of plants.

Study of the interaction of flavonoids with 3-mercaptopropionic acid modified CdTe quantum dots mediated by cetyltrimethyl ammonium bromide in aqueous medium

Flavonoids are polyphenols that help the maintenance of health, aiding the prevention of diseases. In this work, CdTe QDs coated with 3-mercaptopropionic acid (3MPA), with an average size of 2.7nm, were used as photoluminescence probe for flavonoids in different conditions. The interaction between 14 flavonoids and QDs was evaluated in aqueous dispersions in the absence and in the presence of cetyltrimethylammonium bromide (CTAB). To establish a relationship between photoluminescence quenching and the concentration of flavonoids, the Stern-Volmer model was used. In the absence of CTAB, the linear ranges for quercetin, morin and rutin were from 5.0×10^-6molL^-1 to 6.0×10^-5molL^-1 and from 1.0×10^-5molL^-1 to 6.0×10^-4molL^-1 for kaempferol. The sensibility of the Stern-Volmer curves (K_s) indicated that quercetin interacts more strongly with the probe: K_{s quercetin}>K_{s kaempferol}>K_{s rutin}>K_{s morin}. The conjugation extension in the 3 rings, and the acidic hydroxyl groups (positions 3'and 4') in the B-ring enhanced the interaction with 3MPA-CdTe QDs. The other flavonoids do not interact with the probe at 10^-5molL^-1 level. In CTAB organized dispersions, K_{s 3-hydroxyflavone}>K_{s 7-hydroxyflavone}>K_{s flavona}>K_{s rutin} in the range from 1.0×10^-6molL^-1 to 1.2×10^-5molL^-1 for flavones and of 1.0×10^-6molL^-1 to 1.0×10^-5molL^-1 for rutin. Dynamic light scattering, conductometric measurements and microenvironment polarity studies were employed to elucidate the QDs-flavonoids interaction in systems containing CTAB. The quenching can be attributed to the preferential solubility of hydrophobic flavonoid in the palisade layer of the CTAB aggregates adsorbed on the surface of the 3MPA CdTe QDs.

Biomedical Probes Based on Inorganic Nanoparticles for Electrochemical and Optical Spectroscopy Applications

Inorganic nanoparticles usually provide novel and unique physical properties as their size approaches nanometer scale dimensions. The unique physical and optical properties of nanoparticles may lead to applications in a variety of areas, including biomedical detection. Therefore, current research is now increasingly focused on the use of the high surface-to-volume ratios of nanoparticles to fabricate superb chemical- or biosensors for various detection applications. This article highlights various kinds of inorganic nanoparticles, including metal nanoparticles, magnetic nanoparticles, nanocomposites, and semiconductor nanoparticles that can be perceived as useful materials for biomedical probes and points to the outstanding results arising from their use in such probes. The progress in the use of inorganic nanoparticle-based electrochemical, colorimetric and spectrophotometric detection in recent applications, especially bioanalysis, and the main functions of inorganic nanoparticles in detection are reviewed. The article begins with a conceptual discussion of nanoparticles according to types, followed by numerous applications to analytes including biomolecules, disease markers, and pharmaceutical substances. Most of the references cited herein, dating from 2010 to 2015, generally mention one or more of the following characteristics: a low detection limit, good signal amplification and simultaneous detection capabilities.

One step poly(rutin) particle preparation as biocolloid and its characterization

Poly(rutin) p(RT) particles were prepared for the first time via a simple microemulsion polymerization/crosslinking method using l-α lecithin as surfactant, cyclohexane as organic phase and glycerol diglycidyl ether (GDE) as a crosslinking agent. Highly negatively charged p(RT) particles, -48.2 mV, were obtained due to phenolic groups on the particles. It was also confirmed that p(RT) particles are thermally more stable than RT and degradable in PBS at pH7.4., e.g., 11 wt.% can degrade in 1 day and little further degradation was observed over 9 days. The prepared p(RT) particles showed insignificant antibacterial characteristics against common bacteria such as Escherichia coli ATCC8739, Staphylococcus aureus ATCC6538, and Bacillus subtilis ATCC6633 whereas the RT molecules showed significantly better antibacterial characteristics even at low concentrations. Moreover, p(RT) particles were demonstrated for use as drug delivery devices by loading rosmarinic acid (RA) as model drug and showed release capability for up to 6 days by releasing 85% of the loaded RA. Intriguingly, p(RT) particles illustrated enhanced fluorescent properties providing great potential for fluorescent active antioxidant and antibacterial materials in biomedical use.