Showing papers by "Kandasamy Prabakar published in 2019"

Extreme Environment Streptomyces: Potential Sources for New Antibacterial and Anticancer Drug Leads?

Abstract: Antimicrobial resistance (AR) is recognized as one of the greatest threats to public health and in global concern. Consequently, the increased morbidity and mortality, which are associated with multidrug resistance bacteria, urgently require the discovery of novel and more efficient drugs. Conversely, cancer is a growing complex human disease that demands new drugs with no or fewer side effects. Most of the drugs currently used in the health care systems were of Streptomyces origin or their synthetic forms. Natural product researches from Streptomyces have been genuinely spectacular over the recent years from extreme environments. It is because of technical advances in isolation, fermentation, spectroscopy, and genomic studies which led to the efficient recovering of Streptomyces and their new chemical compounds with distinct activities. Expanding the use of the last line of antibiotics and demand for new drugs will continue to play an essential role for the potent Streptomyces from previously unexplored environmental sources. In this context, deep-sea, desert, cryo, and volcanic environments have proven to be a unique habitat of more extreme, and of their adaptation to extreme living, environments attribute to novel antibiotics. Extreme Streptomyces have been an excellent source of a new class of compounds which include alkaloids, angucycline, macrolide, and peptides. This review covers novel drug leads with antibacterial and cytotoxic activities isolated from deep-sea, desert, cryo, and volcanic environment Streptomyces from 2009 to 2019. The structure and chemical classes of the compounds, their relevant bioactivities, and the sources of organisms are presented.

Metal-free multiporous carbon for electrochemical energy storage and electrocatalysis applications

Abstract: Functionalized activated carbon materials are promising metal-free electrocatalysts for low-cost and environmentally benign efficient hydrogen evolution (HER) and oxygen evolution (OER) reactions. The use of rational design and optimized architectures are effective ways to produce numerous catalytic active sites, fast electron/ion movement, and better adsorption capabilities towards reactants. Here, we report a hierarchical multiporous honeycomb carbon network derived from naturally nitrogen enriched broccoli stem biomass and we have extended its application to a flexible wire supercapacitor as well as an efficient OER and HER electrocatalyst. We have achieved the lowest overpotential of 184 mV (vs. reversible hydrogen electrode) for the HER at a current density of 10 mA cm−2, and 301 mV (vs. reversible hydrogen electrode) for the OER, comparatively much better than metal-doped carbon electrocatalysts. The flexible wire supercapacitor achieved an energy density of 3 W h kg−1 at a power density of 450 W kg−1 and a gravimetric specific capacitance of 106 F g−1 at a current rate of 0.5 A g−1.

Environmental Prevalence of Carbapenem Resistance Enterobacteriaceae (CRE) in a Tropical Ecosystem in India: Human Health Perspectives and Future Directives.

Abstract: In the past few decades, infectious diseases have become increasingly challenging to treat, which is explained by the growing number of antibiotic-resistant bacteria. Notably, carbapenem-resistant Enterobacteriaceae (CRE) infections at global level attribute a vast, dangerous clinical threat. In most cases, there are enormous difficulties for CRE infection except a few last resort toxic drugs such as tigecycline and colistin (polymyxin E). Due to this, CRE has now been categorized as one among the three most dangerous multidrug resistance (MDR) pathogens by the US Centres for Disease Control and Prevention (CDC). Considering this, the study of the frequency of CRE infections and the characterization of CRE is an important area of research in clinical settings. However, MDR bacteria are not only present in hospitals but are spreading more and more into the environment, thereby increasing the risk of infection with resistant bacteria outside the hospital. In this context, developing countries are a global concern where environmental regulations are often insufficient. It seems likely that overcrowding, poor sanitation, socioeconomic status, and limited infrastructures contribute to the rapid spread of MDR bacteria, becoming their reservoirs in the environment. Thus, in this review, we present the occurrence of CRE and their resistance determinants in different environmental compartments in India.

Multiscale honeycomb-structured activated carbon obtained from nitrogen-containing mandarin peel: high-performance supercapacitors with significant cycling stability

Abstract: Herein, a facile aqueous method was used to prepare multiscale honeycomb-structured activated carbon from mandarin peels using KOH and NaOH as activation agents, and the prepared multiscale honeycomb-structured activated carbon was carbonized under a nitrogen and argon atmosphere. All samples possessed nitrogen due to its natural abundance and exhibited enhanced specific capacitance, whereas metallic sodium (Na)-intercalated samples, which were formed due to NaOH activation, showed large pore size with increased intercalation capacitance although their surface area was reduced. Potassium has been additionally intercalated during cycling in a KOH solution and helped to sustain the micro/mesoporous honeycomb structure as well as increased the number of O–CO bonds with a concomitant reduction in the number of C–C and CC bonds. The honeycomb carbon retains up to 98% of its initial capacitance even after 7000 cycles. The presence of multiscale porosity in the interconnected carbon network structure enhances the reversible adsorption/desorption of ions in the Helmholtz double layer and hence results in high storage capacity and rate capability of the supercapacitors. The highest energy density of 10.92 W h kg−1 at the power density of 240 W kg−1 has been achieved and maintained up to 7.06 W h kg−1 at the higher power density of 1740 W kg−1. A detailed kinetic study has been employed to better understand the specific capacitance contribution in symmetrical supercapacitors.

Open Atmosphere-Processed Stable Perovskite Solar Cells Using Molecular Engineered, Dopant-Free, Highly Hydrophobic Polymeric Hole-Transporting Materials: Influence of Thiophene and Alkyl Chain on Power Conversion Efficiency

Abstract: Developing efficient and stable perovskite solar cells (PSCs) in open atmosphere desperately requires robust hole-transporting material (HTMs) with high hole conductivity and rich hydrophobicity. Here, we present two dopant-free, highly hydrophobic, donor−π–acceptor conducting polymeric HTMs by interconnecting three monomer units of 4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene, pyrrolo[3,4-c]pyrrole-1,3-dione, and [3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl] (TT) named as R1 and two monomer units of [4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl] and TT named as R2. These two R1 and R2 HTMs integrated in PSCs exhibit an excellent photovoltaic performance of ∼15.8 and ∼13.5% at open atmospheric conditions, respectively. This distinguished photovoltaic performance is strongly correlated with their hole mobility, solubility, and energetic alignment with perovskite valence band. Briefly, the excess thiophene rings with extended alkyl chains in R1 ...

Open Atmosphere-Processed Stable Perovskite Solar Cells Using Molecular Engineered, Dopant-Free, Highly Hydrophobic Polymeric Hole-Transporting Materials: Influence of Thiophene and Alkyl Chain on Power Conversion Efficiency

Abstract: Developing efficient and stable perovskite solar cells (PSCs) in open atmosphere desperately requires robust hole-transporting material (HTMs) with high hole conductivity and rich hydrophobicity. Here, we present two dopant-free, highly hydrophobic, donor−π–acceptor conducting polymeric HTMs by interconnecting three monomer units of 4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene, pyrrolo[3,4-c]pyrrole-1,3-dione, and [3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl] (TT) named as R1 and two monomer units of [4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl] and TT named as R2. These two R1 and R2 HTMs integrated in PSCs exhibit an excellent photovoltaic performance of ∼15.8 and ∼13.5% at open atmospheric conditions, respectively. This distinguished photovoltaic performance is strongly correlated with their hole mobility, solubility, and energetic alignment with perovskite valence band. Briefly, the excess thiophene rings with extended alkyl chains in R1 brought a significant impact on photovoltaic performance due to (i) S-based heterocyclic thiophene strengthening the interaction with the perovskite/HTM interface and increasing its conductivity, (ii) a retarded recombination rate, (iii) high solubility helping to obtain uniform film coverage over perovskite, (iv) the highest occupied molecular orbital level being well aligned with perovskite energy band and (v) increased hydrophobicity. Except the top gold metal contact, the complete PSC device was fabricated in an open atmosphere from a low-temperature solution process and these dopant-free HTMs pave the way for attaining stable and efficient PSCs toward potential applications.

Phylogenetic insight of Nonribosomal peptide synthetases (NRPS) Adenylate domain in Antibacterial potential Streptomyces BDUSMP 02 isolated from Pitchavaram Mangrove.

Abstract: Identification of gene clusters in Streptomyces holds promise for the discovery of regulatory pathways linked to bioactive metabolites. We isolated a broad-spectrum antibacterial potential Streptomyces sp BDUSMP 02 from mangrove sediment. We further found a distinct of phylogeny pattern for NRPS A-domain in the Streptomyces sp BDUSMP 02. The result suggests that Streptomyces sp BDUSMP 02 has the potential to produce a new type of antibacterial compounds belonging to NRPS type.