GREEN TEA EXTRACT IN MICROEMULSION: STABILITY, DERMAL SENSITIZATION AND EFFICACY AGAINST UV INDUCED DAMAGES

Objective: To determine the photoprotective effect of epigallocatechin (EGC) extracted from green tea using microemulsions as a carrier system.Methods: In the present study, EGC was extracted from commercially available branded as well as loose green tea samples. Further, microemulsions (MEs) of these extracts were formulated and were evaluated for their antioxidant and photoprotective effects. MEs were formulated using Capmul MCM as oily phase, Tween 80 as a surfactant and Labrasol as co-surfactant after studying the phase behavior. MEs containing green tea extracts were applied to the rat dorsal skin after exposure to UV radiation (rate of exposure = 9.71 J/cm2, dose = 0.9011 mJ/cm2/sec). The effect of the formulation was evaluated in terms of reduced glutathione level (GSH), radical scavenging activity (DPPH), trans-epidermal water loss (TEWL), irritation potential and histological changes. The EGC content of both types of green tea was estimated using HPTLC and photo-stability of ME formulation was evaluated using FTIR-ATR technique.Results: The content of EGC in loose and branded tea leaf extracts was found to be 0.00322 % w/w and 0.00468 % w/w, respectively. FTIR studies revealed the instability of formulations prepared with water as aqueous phase after UV exposure. However, in the case of PB (pH 7.4) as the aqueous phase in MEs; no change in the spectra of formulations after UV exposure for different time intervals was observed. Results of TEWL studies indicated that the barrier perturbation was not severe which clearly states the safety aspect of the formulation. The extinction coefficient (EC50) value for loose tea and branded tea leaf extract was found to be 170 µg/ml and 79 µg/ml, respectively. The yield of the extract was 0.00322±0.026 % w/w for loose tea and 0.00468±0.150 % w/w for branded tea.Conclusion: The results of the present investigation indicated that pH of the aqueous phase used for preparing the formulation affected the photo-stability of the formulation. Further, MEs prepared using green tea extracts exhibited photoprotective effects. Hence, the green tea extract containing ME formulations have promising potential to be a cosmeceutical.Keywords: Efficacy against uv induced damages, Microemulsion, Dermal sensitizatio

The physicochemistry and percolation behavior of microemulsions as a function of chain length of cosurfactant and surfactant

This study involved investigating phase behavior and physicochemical characterization of microemulsions (MEs) stabilized by mixtures containing polysorbates (C12-C18) as surfactants and n-alkanols (C2-C6) as cosurfactants. Distribution coefficients and Gibbs free energy were also determined for the systems containing polyoxyethylene sorbitan monolaurate (Tween® 20) as surfactant. ME with Tween® 20 as the surfactant and ethanol as the co surfactant exhibited maximium ME area, as well as, water solubilization capacity (WSC). In the presence of all the cosurfactants, values of both of these parameters decreased as the chain length of the surfactant increased with the exception of Tween® 80. This could be attributed to the unsaturated structure of Tween® 80 which possibly allowed for greater spatial configurations of the chain and thus allowing less oil penetration. Furthermore, the transition of w/o MEs to o/w MEs via a bi-continuous structure along the dilution line was confirmed by conductivity, viscosity and droplet size analysis

A new way in nanosensors: gold nanorods for sensing of Fe(III) ions in aqueous media

A novel and systematic method for sensitive detection of Fe3 + ions in aqueous media using gold nanorods (Au NRs) as nanosensors is presented. One of the most rousing achievements is the detection limit which is found to be 100 ppb for Fe3 + ions. The whole procedure takes not more than 10 min which uses surfactant cetyltrimethylammonium bromide (CTAB) capped seed instead of a citrate to overcome the formation of spherical particles in excess amount along with rods. This work also presents a low cost and effective solution for separation of seed mediated grown Au NRs from co-produced spherical nanoparticles formed in solution. The characterization of nanomaterials and interaction of Fe3 + ions with sensor material was studied by UV–vis spectrophotometer to determine optical properties, while scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to determine morphology. The interaction of Fe3 + ions with Au NRs was investigated by surface-enhanced Raman scattering (SERS) using crystal violet (CV) molecule. The aspect ratio (length/diameter) of Au NRs was controlled by the amount of surfactant added. The method reported herein is a simple way to detect and determine Fe3 + ions in aqueous solution at the ppb levels and easily applicable for monitoring of Fe3 + ions in water sample

Control of Alginate Core Size in Alginate-Poly (Lactic-Co-Glycolic) Acid Microparticles

Core-shell alginate-poly (lactic-co-glycolic) acid (PLGA) microparticles are potential candidates to improve hydrophilic drug loading while facilitating controlled release. This report studies the influence of the alginate core size on the drug release profile of alginate-PLGA microparticles and its size. Microparticles are synthesized through double-emulsion fabrication via a concurrent ionotropic gelation and solvent extraction. The size of alginate core ranges from approximately 10, 50, to 100 μm when the emulsification method at the first step is homogenization, vortexing, or magnetic stirring, respectively. The second step emulsification for all three conditions is performed with magnetic stirring. Interestingly, although the alginate core has different sizes, alginate-PLGA microparticle diameter does not change. However, drug release profiles are dramatically different for microparticles comprising different-sized alginate cores. Specifically, taking calcein as a model drug, microparticles containing the smallest alginate core (10 μm) show the slowest release over a period of 26 days with burst release less than 1 %. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s11671-015-1222-7) contains supplementary material, which is available to authorized users

Physicochemistry and Percolation behavior of Microemulsions as a Function of Chain Length of Cosurfactant and Surfactant

The study involved investigations on phase behavior and physicochemical characterization of microemulsions (MEs) stabilized by mixture containing polysorbates (C12-C18) as surfactants and n-alkanols (C2-C6) as cosurfactant. Distribution coefficient and Gibbs free energy were also determined for systems containing Tween 20 as surfactant. ME having Tween 20 as surfactant and ethanol as cosurfactant was found to exhibit maximium ME region as well as water solubilization capacity (WSC). Values of both these parameters were found to decrease as chain length of surfactant increased in all cases of alkanols with exception of Tween 80. This could be attributed to unsaturated structure of Tween 80 which presumably caused folding of chain and lesser oil penetration. Furthermore, the transition of w/o MEs to o/w MEs via bicontinuous structure along the dilution line was confirmed by conductivity, viscosity and droplet size analysis

Plasmonic detection of Cd2+ ions using surface - enhanced Raman scattering active core – shell nanocomposite

The present study was structured to address development of an efficient devise for sensing of toxic Cd2+ ions at trace level in aqueous media. In order to achieve this objective, the speckled core–shell nanocomposites (NCs) of silica-gold (SiO2@Au) using ~30 nm diameter of spherical gold nanoparticles (Au NPs) with 420 nm diameter of silica cores was synthesized. Au NPs showed the surface plasmon resonance (SPR) peak at 522 nm and spherical core–shell particles at 541 nm. Both Au NPs and SiO2@Au solutions were found to be sensitive to Cd2+ ions in aqueous sample. The colour change occurred in presence of SiO2@Au at 0.1 ppm (100 ppb) of Cd2+ ions whereas 2 ppm (2000 ppb) concentration of Cd2+ ions was necessary for the colour change in Au NPs solution confirmed that SERS active SiO2@Au core–shell NCs 20 times more sensitive compared to Au NPs. The technique using SiO2@Au NCs is quantitative between 100 and 2000 ppb (0.1 to 2 ppm) while effective but non-quantitative above upto 10 ppm, the maximum concentration studied in present investigation. The detection limit using SiO2@Au NCs is 100 ppb (0.1 ppm) while Au NPs is able to detect Cd2+ as low as 2000 ppb (2 ppm). The scanning electron microscopy (SEM) of Au NPs and SiO2@Au particles showed aggregation of Au NPs and SiO2@Au NCs in the presence of Cd2+ ions. The surface enhanced Raman spectroscopy (SERS) was used to compare sensitivities of Au NPs and SiO2@Au towards Cd2+ ions and confirmed that SiO2@Au core–shell NCs is 20 times more sensitive than Au NPs

Trace colorimetric detection of Pb2+ using plasmonic gold nanoparticles and silica-gold nanocomposites

A novel, simple and highly sensitive plasmonic colorimetric method is developed for the detection of Pb2+ in aqueous samples. The method is based on the aggregation of gold nanoparticles (AuNPs) or SiO2core-Au-shell nanocomposites (SiO2@Au NCs) in the presence of Pb2+ ions. It was found that the colour of AuNPs or SiO2@Au NCs changes in the presence of Pb2+ ions and the intensity of surface plasmon resonance (SPR) peak of AuNPs or SiO2@Au NCs decreased. Thus, the synthesis of sensitive surface enhanced Raman scattering (SERS) materials; similar to 20 nm spherical AuNPs and similar to 360 nm SiO2@Au NCs leads to the development of nanosensor for the detection of Pb2+ ions. Both AuNPs and SiO2@Au NCs by virtue of their versatility show localized surface plasmon resonance (LSPR) peaks at 522 nm and 541 nm respectively. The synthesized AuNPs, SiO2@Au NCs and analyte samples prepared were characterised using a scanning electron microscope, a transmission electron microscope and a UV-vis spectrophotometer. The SERS study was also used to compare sensitivities of both AuNPs and SiO2@Au NCs towards Pb2+ ions using crystal violet (CV) as a target molecule. The analyte Pb2+ was detected as low as 500 nM using 20 nm AuNPs and 50 nM using 360 nm SiO2@Au NCs. It was confirmed that SiO2@Au NCs were found ten times more sensitive as compared to AuNPs for the detection of Pb2+ ions

Plasmonic nanoparticles and their analytical applications: a review

Plasmonic nanoparticles (NPs) have been reviewed herein for their fascinating optical properties in a wide spectral range and for their various applications. The surface plasmon resonance (SPR) bands of metal NPs can be tuned from visible to near infrared region by varying the shape of the metal NPs. As a result, the tuning of the SPR band over a spectral range is possible by making plasmonic NPs of different shapes. This review emphasizes fundamental studies of plasmonic NPs and nanocomposites with well-defined and controlled shapes that have several analytical applications such as molecular detection and determination in different fields. This review describes how oxidative etching and kinetic control can be utilized to manipulate the shape and optical properties of NPs. This review also describes the specific examples of the sensing applications of the localized surface plasmon resonance studies in which the researchers use both wavelength shift and surface-enhanced Raman scattering sensing to detect the molecules of chemical and biological relevance. The review ends with a perspective of the field, identifying the main challenges to be overcome and suggesting areas where the most promising developments are likely to happen in future