Anju Chadha

Bio: Anju Chadha is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Candida parapsilosis & Enantiomeric excess. The author has an hindex of 30, co-authored 135 publications receiving 2800 citations. Previous affiliations of Anju Chadha include Indian Institute of Science & National Institutes of Health.

Enantio- & chemo-selective preparation of enantiomerically enriched aliphatic nitro alcohols using Candida parapsilosis ATCC 7330

Abstract: Enantiomerically pure β- and γ-nitro alcohols were prepared from their respective nitro ketones by asymmetric reduction mediated by the biocatalyst, Candida parapsilosis ATCC 7330 under optimized reaction conditions (ee up to >99%; yields up to 76%). This biocatalyst exhibits high chemoselectivity and reduces the keto group in preference to nitro group along with good enantioselectivity to produce enantiomerically enriched nitro alkanols. The asymmetric reduction of aliphatic nitro ketones was carried out in water with ethanol as cosolvent and glucose as cosubstrate using the whole cells of Candida parapsilosis ATCC 7330 in much lesser time (4 h). For the first time, the biocatalytic asymmetric reduction of the following ketones is reported here: 1-nitro-butan-2-one, 1-nitro-pentan-2-one, 3-methyl-1-nitro-butan-2-one and 1-cyclohexyl-2-nitroethanone to produce (R)-alcohols [ee up to 79%, yield up to 74%] and 1-nitro-hexan-2-one and 1-nitro-heptan-2-one to produce (S)-alcohols [ee up to 81%, yield up to 76%].

Sodium Borohydride Reduction and Selective Transesterification of β-Keto Esters in a One-pot Reaction under Mild Conditions

Abstract: An efficient and simple one-pot method of preparing β-hydroxy esters by sodium borohydride reduction cum selective transesterification of β-keto esters under mild conditions is described.

Self-Assembled Inhalable Immunomodulatory Silk Fibroin Nanocarriers for Enhanced Drug Loading and Intracellular Antibacterial Activity.

Abstract: In this study, a pH-induced self-assembly-based method has been developed to form silk fibroin nanoparticles (SFN-2) with a higher drug loading capacity (21.0 ± 2.1%) and cellular uptake than that of silk fibroin particles produced by a conventional desolvation method (SFN-1). Using the self-assembly method, rifampicin-encapsulated silk fibroin nanoparticles (R-SFN-2) were prepared with a size of 165 ± 38 nm at an optimum pH of 3.8. In silico analysis reveals that at acidic pH, the amino acid side chain charge neutralization of acidic residues, especially GLU64, promotes the formation of additional favorable interactions between the silk fibroin and the drug. The SFN-2 also possess a good aerosol property with a mass median aerodynamic diameter of 3.82 ± 0.71 μm and fine particle fraction of 64.0 ± 1.4%. These SFN-2 particles were selectively endocytosed by macrophages through clathrin- and caveolae-mediated endocytosis with a higher uptake efficiency (66.2 ± 2.1%) and were found to exhibit a sustained drug release in the presence of macrophage intracellular lysates. The cytokine and biomarker expression analyses revealed that SFN-2 could exhibit an immunomodulatory effect by polarizing the macrophages to an initial M1 phase and later M2 phase. Further, R-SFN-2 also exhibited an enhanced and sustained intracellular antibacterial activity against Mycobacterium smegmatis-infected macrophages than free rifampicin. Thus, the self-assembled silk fibroin particles with immunomodulatory action combined with a good aerosol and intracellular drug release property can be an attractive choice as a carrier for developing pulmonary drug delivery systems.

Whole resting cells vs. cell free extracts of Candida parapsilosis ATCC 7330 for the synthesis of gold nanoparticles

Abstract: The cell free extracts of Candida parapsilosis ATCC 7330 are more efficient than the whole resting cells of the yeast in the synthesis of directly usable gold nanoparticles as revealed by this systematic study. Cell free extracts yielded gold nanoparticles of hydrodynamic diameter (50–200 nm). In this study, the total protein concentration influences the nanofabrication and not only the reductase enzymes as originally thought. Powder X-ray diffraction studies confirm the crystalline nature of the gold nanoparticles. Fourier Transform Infra Red spectroscopy and thermal gravimetric analysis suggests that the biosynthesized gold nanoparticles are capped by peptides/proteins. Dispersion experiments indicate a stable dispersion of gold nanoparticles in pH 12 solutions which is also confirmed by electron microscopic analysis and validated using a surface plasmon resonance assay. The effectiveness of the dispersed nanoparticles for the reduction of 4-nitrophenol using sodium borohydride as a reductant further confirms the formation of functional gold nanoparticles. It is also reported that gold nanoparticles with mean particle diameter of 27 nm are biosynthesized inside the whole cell by transmission electron microscopy analysis. With optimized reaction conditions, maximum gold bioaccumulation with the 24 h culture age of the yeast with cellular uptake of ~1010 gold atoms at the single cell level is achieved but it is not easy to extract the gold nanoparticles from the whole resting cells.

A simple and efficient method for mild and selective oxidation of propargylic alcohols using TEMPO and calcium hypochlorite

Abstract: Oxidation of propargylic alcohols to the corresponding aldehydes and ketones was achieved at room temperature using 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and calcium hypochlorite (Ca(OCl)2). Propargylic diols yielded corresponding dialdehydes as the product. This system was found to be very efficient for both the electron donating and electron withdrawing groups such as methoxy and nitro substituted alcohols, respectively. This method does not require any additives and demonstrates the controlled, selective oxidation of propargylic alcohols affording up to 97% isolated yield.

Kirk-Othmer Encyclopedia of Chemical Technology数据库介绍及实例

Abstract: 介绍了Kirk—Othmer Encyclopedia of Chemical Technology（化工技术百科全书）（第五版）电子图书网络版数据库，并对该数据库使用方法和检索途径作出了说明，且结合实例简单地介绍了该数据库的检索方法。

A comprehensive review on biodiesel as an alternative energy resource and its characteristics

Abstract: As the fossil fuels are depleting day by day, there is a need to find out an alternative fuel to fulfill the energy demand of the world. Biodiesel is one of the best available resources that have come to the forefront recently. In this paper, a detailed review has been conducted to highlight different related aspects to biodiesel industry. These aspects include, biodiesel feedstocks, extraction and production methods, properties and qualities of biodiesel, problems and potential solutions of using vegetable oil, advantages and disadvantages of biodiesel, the economical viability and finally the future of biodiesel. The literature reviewed was selective and critical. Highly rated journals in scientific indexes were the preferred choice, although other non-indexed publications, such as Scientific Research and Essays or some internal reports from highly reputed organizations such as International Energy Agency (IEA), Energy Information Administration (EIA) and British Petroleum (BP) have also been cited. Based on the overview presented, it is clear that the search for beneficial biodiesel sources should focus on feedstocks that do not compete with food crops, do not lead to land-clearing and provide greenhouse-gas reductions. These feedstocks include non-edible oils such as Jatropha curcas and Calophyllum inophyllum , and more recently microalgae and genetically engineered plants such as poplar and switchgrass have emerged to be very promising feedstocks for biodiesel production. It has been found that feedstock alone represents more than 75% of the overall biodiesel production cost. Therefore, selecting the best feedstock is vital to ensure low production cost. It has also been found that the continuity in transesterification process is another choice to minimize the production cost. Biodiesel is currently not economically feasible, and more research and technological development are needed. Thus supporting policies are important to promote biodiesel research and make their prices competitive with other conventional sources of energy. Currently, biodiesel can be more effective if used as a complement to other energy sources.

Cancer risk assessment, indicators, and guidelines for polycyclic aromatic hydrocarbons in the ambient air.

Abstract: Polycyclic aromatic hydrocarbons (PAHs) are formed during incomplete combustion. Domestic wood burning and road traffic are the major sources of PAHs in Sweden. In Stockholm, the sum of 14 different PAHs is 100-200 ng/m(3) at the street-level site, the most abundant being phenanthrene. Benzo[a]pyrene (B[a]P) varies between 1 and 2 ng/m(3). Exposure to PAH-containing substances increases the risk of cancer in humans. The carcinogenicity of PAHs is associated with the complexity of the molecule, i.e., increasing number of benzenoid rings, and with metabolic activation to reactive diol epoxide intermediates and their subsequent covalent binding to critical targets in DNA. B[a]P is the main indicator of carcinogenic PAHs. Fluoranthene is an important volatile PAH because it occurs at high concentrations in ambient air and because it is an experimental carcinogen in certain test systems. Thus, fluoranthene is suggested as a complementary indicator to B[a]P. The most carcinogenic PAH identified, dibenzo[a,l]pyrene, is also suggested as an indicator, although it occurs at very low concentrations. Quantitative cancer risk estimates of PAHs as air pollutants are very uncertain because of the lack of useful, good-quality data. According to the World Health Organization Air Quality Guidelines for Europe, the unit risk is 9 X 10(-5) per ng/m(3) of B[a]P as indicator of the total PAH content, namely, lifetime exposure to 0.1 ng/m(3) would theoretically lead to one extra cancer case in 100,000 exposed individuals. This concentration of 0.1 ng/m(3) of B[a]P is suggested as a health-based guideline. Because the carcinogenic potency of fluoranthene has been estimated to be approximately 20 times less than that of B[a]P, a tentative guideline value of 2 ng/m(3) is suggested for fluoranthene. Other significant PAHs are phenanthrene, methylated phenanthrenes/anthracenes and pyrene (high air concentrations), and large-molecule PAHs such as dibenz[a,h]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, and indeno[1,2,3-cd]pyrene (high carcinogenicity). Additional source-specific indicators are benzo[ghi]perylene for gasoline vehicles, retene for wood combustion, and dibenzothiophene and benzonaphthothiophene for sulfur-containing fuels.