No abstract

Extensive research on tea catechins, mainly (-)-epigallocatechin gallate, has shown numerous health promoting effects. However, various clinical studies demonstrated several issues associated with tea catechins which account for their poor systemic bioavailability. In order to improve pharmacological activity and bioavailability of natural tea catechins, two major strategies have been adopted to date which include synthesizing catechin analogs/prodrugs and the development of novel drug delivery systems. In this review, we provide a detailed account of novel synthetic analogs/prodrugs as well as novel drug delivery approaches used for natural tea catechins to make them therapeutically potent drug-like molecules.

This study reports hydrothermally grown zinc oxide nanorod-based metal-semiconductor-metal ultraviolet detectors with palladium metal as the electrodes. The zinc oxide nanorods were deposited on glass substrates in two steps, seed layer deposition and growth of nanorods. The structural and optical properties of nanorods were examined using scanning electron microscopy and ultraviolet-vis spectroscopy, respectively. The scanning electron microscopy image showed that the growth of nanorods was uniform, and the ultraviolet-vis results indicate that the bandgap of zinc oxide nanorods was 3.23 eV. For metal-semiconductor-metal devices, interdigited metal electrodes with equal interelectrode spacing and a width of 0.3 mm were deposited above the zinc oxide nanorod thin films with a shadow mask using a thermal evaporation system. The current-voltage characteristics of the metalsemiconductor-metal detector were investigated and it showed a contrast ratio of approximately 2.10 and responsivity of approximately 0.199 A/W at 1.8 V. These results are expected to be beneficial to fabricating cheap and practical ultraviolet detection applications.

Zinc oxide has emerged as an attractive material for various applications in electronics, optoelectronics, biomedical and sensing. The large excitonic binding energy of 60 meV at room temperature as compared to 25 meV of gallium nitride, an III-V compound makes ZnO an efficient light emitter in the ultraviolet (UV) spectral region and hence favourable for optoelectronic applications. The high conductivity and transparency of ZnO makes it important for applications like transparent conducting oxides (TCO) and thin-film transistors (TFT). In this paper, the optoelectronic, electronic and other properties that make ZnO attractive for a variety of applications are discussed. Various applications of ZnO thin film and its devices such as light-emitting diodes (LED), UV sensors, biosensors, photodetectors and TFT that have been described by various research groups are presented.

Green tea; catechins; (-)-EGCG O-acyl derivatives; antitumor activity.