The photocatalyst-enzyme coupled system for artificial photosynthesis process is one of the most promising methods of solar energy conversion for the synthesis of organic chemicals or fuel. Here we report the synthesis of a novel graphene-based visible light active photocatalyst which covalently bonded the chromophore, such as multianthraquinone substituted porphyrin with the chemically converted graphene as a photocatalyst of the artificial photosynthesis system for an efficient photosynthetic production of formic acid from CO(2). The results not only show a benchmark example of the graphene-based material used as a photocatalyst in general artificial photosynthesis but also the benchmark example of the selective production system of solar chemicals/solar fuel directly from CO(2).

The successful development of a photocatalyst/biocatalyst integrated system that carries out selective methanol production from CO2 is reported herein. The fine-tuned system was derived from a judicious combination of graphene-based visible light active photocatalyst (CCG-IP) and sequentially coupled enzymes. The covalent attachment of isatin-porphyrin (IP) chromophore to chemically converted graphene (CCG) afforded newly developed CCG-IP photocatalyst for this research endeavor. The current work represents a new benchmark for carrying out highly selective methanol formation from CO2 in an environmentally benign manner.

The successful development of a triazine based covalent organic framework as an inexpensive and highly efficient visible light active flexible film photocatalyst for solar fuel production from CO2is described.

The utilization of CO 2 for production of solar fuels/chemicals is gaining increasing importance due to worldwide fossil-fuel shortage and global warming. As a means to achieve this, we herein report on the synthesis and development of a graphene-based visible light active photocatalyst (CCG-BODIPY) which is chemically converted graphene (CCG) covalently bonded to a light harvesting BODIPY molecule (1picolylamine-2-aminophenyl-3-oxy-phenyl-4,4 0 -difluoro-1,3,5,7-tetramethyl-2,6-diethyl-4-bora-3a,4adiaza-s-indacene-triazine). The photocatalyst-biocatalyst coupled system developed using CCG-BODIPY as photocatalyst functions in a highly efficient manner, leading to high NADH regeneration (54.02 AE 0.61%), followed by its consumption in exclusive formic acid production (144.2 AE 1.8 mmol) from CO 2 . The present research endeavour highlights the development and application of a graphene based photocatalyst for direct solar fuel formation from carbon dioxide.

Numerous reports have shown that mitochondrial dysfunctions play a major role in apoptosis of Leishmania parasites, but the endoplasmic reticulum (ER) stress-induced apoptosis in Leishmania remains largely unknown. In this study, we investigate ER stress-induced apoptotic pathways in Leishmania major using tunicamycin as an ER stress inducer. ER stress activates the expression of ER-localized chaperone protein BIP/GRP78 (binding protein/identical to the 78-kDa glucose-regulated protein) with concomitant generation of intracellular reactive oxygen species. Upon exposure to ER stress, the elevation of cytosolic Ca 2؉ level is observed due to release of Ca 2؉ from internal stores. Increase in cytosolic Ca 2؉ causes mitochondrial membrane potential depolarization and ATP loss as ablation of Ca

Covalent organic frameworks (COFs) have emerged as a promising light-harvesting module for artificial photosynthesis and photovoltaics. For efficient generation of free charge carriers, the donor–acceptor (D-A) conjugation has been adopted for two-dimensional (2D) COFs recently. In the 2D D-A COFs, photoexcitation would generate a polaron pair, which is a precursor to free charge carriers and has lower binding energy than an exciton. Although the character of the primary excitation species is a key factor in determining optoelectronic properties of a material, excited-state dynamics leading to the creation of a polaron pair have not been investigated yet. Here, we investigate the dynamics of photogenerated charge carriers in 2D D-A COFs by combining femtosecond optical spectroscopy and non-adiabatic molecular dynamics simulation. From this investigation, we elucidate that the polaron pair is formed through ultrafast intra-layer hole transfer coupled with coherent vibrations of the 2D lattice, suggesting a mechanism of phonon-assisted charge transfer.

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BackgroundPeroxidase represents a heterogeneous group of distinct enzyme family that plays extremely diverse biological functions. Ascorbate peroxidase from Leishmania major (LmAPX) has been shown to be central to the redox defense system of Leishmania. To investigate further its exact physiological role in Leishmania, we attempted to create LmAPX -knockout mutants by gene replacement in L. major strains.Methodology/Principal FindingsThe null mutant cell culture contains a higher percentage of metacyclic and apoptotic cells compared to both wild type and LmAPX overexpressing cells. Flowcytometric analysis reveals the presence of a higher concentration of intracellular H2O2, indicative of increased oxidative stress in parasites lacking LmAPX. IC50 value for exogenously added H2O2 shows that deletion of LmAPX in L. major renders the cell more susceptible to H2O2. Real time PCR studies demonstrate an elevated mRNA level of non-selenium glutathione peroxidase in LmAPX null mutant cell line, suggesting that these enzymes were induced to compensate the LmAPX enzyme. The null mutant cells exhibit hypervirulence after infection with macrophages as well as inoculation into BALB/c mice; in contrast, overexpressing cells show avirulence.Conclusions/SignificanceCollectively, these data provide strong evidence that LmAPX is an important factor for controlling parasite differentiation and survival within macrophages.