Colorimetric and fluorescence sensing of fluoride anions with potential salicylaldimine based schiff base receptors

Salicylaldimine based schiff base receptors with different substituents showing fluorescent enhancement in the presence of fluoride anion was visualized through naked eye as well as by change in spectral properties (UV–vis and fluorescent techniques). The reason for such fluorescence enhancement may be due to hydrogen bond interaction between receptor recognition site and fluoride anion. Such a hydrogen bond interaction creates a six-membered transition state, which avoids quenching processes. To support this, fluorescence enhancement factor (FEF) was calculated and it was found to be more (FEF = 652) for –NO₂ substituted receptor compared to other receptors.     

Construction of Copper Removing Bacteria Through the Integration of Two-Component System and Cell Surface Display

Synthetic biological systems are becoming more and more feasible for commercial and medical purposes through the genetic engineering of several components. The simple assembly of a genetic circuit was shown to stimulate the removal of copper by bacteria through the engineering of a two-component system. The CusSR two-component systems is a regulator of Escherichia coli copper homeostatic system. In this system, genetic circuits of CusSR were fused to a cell surface display system for metal adsorption; this system is suitable for the display of a copper binding peptide through outer membrane protein C (OmpC). E. coli ompC codes for an outer membrane pore protein (porin) are induced at high osmolarity and temperature, which can also be used as an anchoring motif to accept the passenger proteins. The bacteria that produce the chimeric OmpC containing the copper binding peptide adsorbed maximum concentrations of 92.2 μmol of Cu(2+)/gram dry weight of bacterial cells. This synthetic bacterial system senses the specific heavy metal and activates a cell surface display system that acts to remove the metal.     

Novel two step synthesis of bis/Mono 1-aryl-1H-tetrazole-5-carboxylic acid

Some novel compounds of bis/mono 1-aryl-1H-tetrazole-5-carboxylic acid are synthesized by the hydrolysis of two different synthesized esters, they are ethyl-1-aryl-1H-tetrazole-5-carboxylate and ethyloxo(1-aryl-1H-tetrazol-5-yl)acetate. The ethyl-1-aryl-1H-tetrazole-5-carboxylate is resistant to get hydrolyzed, whereas the ethyloxo(1-aryl-1H-tetrazol-5-yl) acetate undergoes hydrolysis process and converts the ester to title compound. All the synthesized compounds are characterized by IR, ¹H and ¹³C NMR, mass and elemental analysis.The ethyl-1-aryl-1H-tetrazole-5-carboxylateis optimized by DFT B3LYP method and the HOMO and LUMO energy is 5.14?eV and also there is a formation of a weak bond between O₁₈ and C₈ as observed from the AIM analysis result.     

Microbial synthesis of silver nanoparticles by Bacillus sp.

A silver resistant Bacillus sp. was isolated through exposure of an aqueous AgNO₃ solution to the atmosphere. Silver nanoparticles were synthesized using these airborne bacteria (Bacillus sp.). Transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analyses confirmed that silver nanoparticles of 5–15 nm in size were deposited in the periplasmic space of the bacterial cells; a preferable cell surface location for the easy recovery of biogenic nanoparticles.     

Purification and biochemical characterization of two major thermophilic xylanase isoforms (T70 and T90) from xerophytic Opuntia vulgaris plant spp.

Thermostable xylanase isoforms T₇₀ and T₉₀ were purified and characterized from the xerophytic Opuntia vulgaris plant species. The enzyme was purified to homogeneity employing three consecutive steps. The purified T₇₀ and T₉₀ isoforms yielded a final specific activity 134.0 and 150.8 U mg^?1 protein, respectively. The molecular mass of these isoforms was determined to be 27 kDa. The optimum pH for the T₇₀ and T₉₀ xylanase isoforms was 5.0 and the temperature for optimal activity was 70 and 90 °C, respectively. The Km value of T₇₀ and T₉₀ enzyme isoforms was 3.49, 2.1 mg ml^?1, respectively when oat spelt xylan was used as a substrate. The T₇₀ had a Vmax of 10.4 μmol min^?1 mg^?1, and T₉₀ had a Vmax of 8.9 μmol min^?1 mg^?1, respectively. In the presence of 10 mM Co²⁺, and Mn²⁺ the activity of T₇₀ and T₉₀ isoforms increased, where as 90 % inhibition was noted with of the use 10 mM Hg²⁺, Cd²⁺, Cu²⁺, Zn²⁺ while partial inhibition was observed in the presence of Fe³⁺, Ni²⁺, Ca²⁺and Mg²⁺. The T₇₀ and T₉₀ isoforms retained nearly 50 % activity in the presence of 2.0 M urea, while use of 40 mM SDS lowered the activity nearly 38–41 %. The substrate specificity of both T₇₀ and T₉₀ isoforms showed maximum activity for oat spelt xylan. Western blot, immunodiffusion, and in vitro inhibition assays confirmed reactivity of the T₉₀ isoform with polyclonal anti-T₉₀ antibody raised in rabbit, as well as cross-reactivity of the antibody with the T₇₀ xylanase isoform.     

A Chimeric Two-Component Regulatory System-Based <Emphasis Type="Italic">Escherichia coli</Emphasis> Biosensor Engineered to Detect Glutamate

In this study, we constructed amino acid biosensors that can be used as a high-throughput system to screen microorganisms that produce glutamate. The biosensors are based on two-component regulatory systems (TCRSs) combined with green fluorescent protein (GFP) as a reporter. A chimeric DegS/EnvZ (DegSZ) TCRS was constructed by fusing the N-terminal domain of the sensor kinase DegS from Planococcus sp. PAMC21323 with the catalytic domain of the osmosensor EnvZ from Escherichia coli to control expression of gfp in response to glutamate. gfp was controlled by the ompC promoter through the activated response regulator OmpR-P. The chimeric TCRS-based biosensors showed a 4-fold increase in the fluorescent signal after adding glutamate. A linear correlation was observed between fluorescence intensity and exogenously added glutamate concentration. The chimeric TCRS-based biosensor was used to determine glutamate concentration at the single-cell level by fluorescence-activated cell sorting. Therefore, this biosensor can be used to isolate novel gene products and optimize pathways involved in amino acid production.     

Stabilization of E-type antiferromagnetic ordering in La and Y substituted orthorhombic LuMnO3: A first-principles study

We carry out first principles density functional theory calculations of non-lone pairs, namely, La and Y substituted orthorhombic LuMnO₃, to verify the generality of symmetry breaking effects observed in the lone pair cations substituted orthorhombic rare earth manganites. Our calculations revealed that similar to lone pair cations ordering at the A-site of LuMnO₃, non-lone pair cations ordering also results in the lowering of the symmetry thereby proving that the symmetry breaking with A-site ordering is a generic effect. Interestingly, we were able to stabilize the large radius La substituted LuMnO₃ into an E-type antiferromagnetic (E-AFM) phase, in contrast to the normally expected A-type antiferromagnetic (A-AFM) phase of large radius rare earth manganites such as LaMnO₃.     

Heteropolyacid-encapsulated TiHY zeolite as an inorganic photosynthetic reaction center mimicking the plant systems

A tremendous breakthrough was required for the researchers trying to find a way to photodecomposition of water by using semiconductor photocatalysts without electricity. In this regard, we attempted to prepare the heteropolyacid (HPA)-encapsulated TiHY zeolite a new photocatalyst mimicking the plant photosynthetic system. This photocatalyst (0.3 g/40 ml) was observed to generate hydrogen (4.08±0.7 μl/h) and oxygen (6.86±0.7 μl/h) from the aqueous solutions upon illumination by two photon reactions (UV and visible lights), which is quite analogous to the “Z-scheme” mechanism for plant photosynthetic systems. The turnover number of the photocatalyst was determined to be 11 with the quantum yield of the water splitting about 27±6% at 352 nm. Thus, this inorganic material must be very useful as a reaction center mimicking the plant photosynthetic system without electrical energy.