Phototriggered structures: Latest advances in biomedical applications

Non-invasive control of the drug molecules accessibility is a key issue in improving diagnostic and therapeutic procedures. Some studies have explored the spatiotemporal control by light as a peripheral stimulus. Phototriggered drug delivery systems (PTDDSs) have received interest in the past decade among biological researchers due to their capability the control drug release. To this end, a wide range of phototrigger molecular structures participated in the DDSs to serve additional efficiency and a high-conversion release of active fragments under light irradiation. Up to now, several categories of PTDDSs have been extended to upgrade the performance of controlled delivery of therapeutic agents based on well-known phototrigger molecular structures like o-nitrobenzyl, coumarinyl, anthracenyl, quinolinyl, o-hydroxycinnamate and hydroxyphenacyl, where either of one endows an exclusive feature and distinct mechanistic approach. This review conveys the design, photochemical properties and essential mechanism of the most important phototriggered structures for the release of single and dual (similar or different) active molecules that have the ability to quickly reason of the large variety of dynamic biological phenomena for biomedical applications like photo-regulated drug release, synergistic outcomes, real-time monitoring, and biocompatibility potential

A low-overpotential nature-inspired molecular chromium water oxidation catalyst

The function of tyrosine Yz in photosystem II (PSII) has been considered as a model for establishing a new homogeneous water oxidation catalyst (WOC). In this work, we designed and synthesized a diphenoxybased salen-type Schiff base ligand (L) in order to overcome the problems that so far have prevented the use of chromium complexes as water oxidation catalysts (WOCs). Cyclic voltammetry measurements performed in the alkaline solution of [Cr(L-2H)Cl] (1) displayed a large irreversible oxidation waves, corresponding to the catalytic water oxidation. The main species in the catalytically active solutions is found to be [Cr(L-2H)ClOH]-∙ The proposed catalytic system generates a current density (J) of 1.0mA cm2 at the relatively low overpotential (ƞ) of 0.426 V with a high turnover frequency (TOF) of 49.7 s-1. A comprehensive mechanistic study was carried out based on the results of experiments, calculations and according to previous works. The computational calculations supported the importance of the uncoordinated eOH groups present in the ligand moiety of the complex for the oxidation of Cr3+ to Cr4+