Extracellular pH influences the mode of cell death in human colon adenocarcinoma cells subjected to photodynamic treatment with chlorin p6

Effect of varying extracellular pH on mode of cell death induced by photodynamic action of chlorin p6 was investigated in human colon carcinoma (Colo-205) cells. At an extracellular pH of 7.4, compared to cells treated with chlorin p6 in dark, the photodynamically treated cells showed reduction in mitochondrial membrane potential, an increase in ADP/ATP ratio (1:2) and a large percentage of cells with chromatin condensation. In contrast, when photodynamic treatment and post irradiation incubation was carried out in acidic medium (pH 6.5), total loss of mitochondrial membrane potential, a marked increase in ADP/ATP ratio (1:33) and increased damage to plasma membrane were observed. Further, cells subjected to photodynamic treatment in a medium of pH 7.4 showed twofold increase in caspase-3 activity as compared to photodynamic treatment at pH 6.5. These results suggest that chlorin p6 mediated photodynamic action induces apoptotic cell death when extracellular pH is 7.4 whereas necrosis is more predominant under condition when extracellular pH is 6.5.     

Evaluation of contributions to the uncertainty of cholesterol determination in human serum by means of gas chromatography/(quadrupole-) mass spectrometry

 The uncertainty budget of the determination of cholesterol in a reference material (freeze-dried human serum) by isotope dilution mass spectrometry (IDMS) was evaluated. Measurements were run on a GC/quadrupole MS. A nested experimental design combined with a corresponding model for the analysis of variance (ANOVA) revealed the components making up the total uncertainty of the determinations. The coefficient of variation (CV) of the sole GC/MS-step was 0.47%, while that of the sample preparation including hydrolyzation, extraction and derivatization was 0.84%. This made the in-laboratory (overall) CV 0.96%. In addition, there was a vial-to-vial effect of 1.00% probably due to both inhomogeneity of the pooled material and lack of reproducibility of the filling procedure (including freeze drying) of the supplier as well as the reconstitution prior to use in the laboratory. These contributions sum up to an overall CV of a single determination of about 1.4%. Received: 17 October 1996/Revised: 14 November 1996/Accepted: 18 November 1996     

Current perspectives on quinazolines with potent biological activities: A review

Quinazoline is a heterocyclic compound having biological activities. It is aromatic in nature having bicyclic structure containing benzene ring and pyrimidine ring. Quinazoline and its derivatives are found to have wide range of biological activities that is anticancer, analgesic, antimicrobial, antihypertensive, anticonvulsant, antimalarial, antitumor, and anti-tubercular activities. The purpose of this review is to highlight the recent researches made by researchers on various biological activities of quinazoline derivatives on different targets.     

Studies on stability of bi-functional P3HT:PCBM:rubrene optoelectronic devices

Investigations are carried out for stability in photovoltaic response of bifunctional electroluminescent and photovoltaic devices, based on ternary blend of poly(3-hexylthiophene) (P3HT), phenyl [6,6′]C₆₁ butyric acid methyl ester (PCBM), and 5,6,11,12-tetraphenylnaphthacene (rubrene). P3HT and PCBM are important and the most frequent materials used for photovoltaic applications, therefore, for relative comparison, photovoltaic cells were also prepared using a binary mixture of P3HT and PCBM. Devices based on the ternary blend exhibited better stability in all photovoltaic parameters and the lifetime was almost doubled, but their photovoltaic efficiency was lower than that of those based on the binary blend. Longer lifetime of ternary blend devices is because of a relatively better thermal, electrochemical, and morphological stabilities of the ternary blend system. However, the lower efficiencies are because of the reduced photo-current and low fill factor (FF) due to an increased recombination and introduction of defects/trapping sites by rubrene molecules.     

Recovery of plutonium and cerium from alumina crucible

Journal of Radioanalytical and Nuclear Chemistry - Plutonium recovery is inevitable from plutonium bearing alumina crucibles generated over the years as part of carbon analysis during chemical...     

Effective removal of 4-Aminophenol from aqueous environment by pea (Pisum sativum) shells activated with sulfuric acid: Characterization,isotherm, kinetics and thermodynamics

The threat of phenol contamination in aquatic ecosystems is significant for the health of the earth's water systems as well as all humans on it. The present study was conducted to synthesize a cost-effective adsorbent (pea shells activated with sulfuric acid, PSASA) from agriculture waste (pea shells) and its use for effective removal of toxic 4-Aminophenol (4-AP). Newly designed PSASA exhibited significant adsorption of 4-AP which was confirmed by SEM, FT-IR, and XRD analysis. Surface topography confirmed high unevenness of the PSASA surface and the macroporous feature of the PSASA was confirmed by BET analysis. . Multiple testing was done to see how various factors affected adsorption such as adsorbent dose, temperature, pH, PZC, the effect of KCl and urea addition and the effect of the initial concentration of 4-AP. A drop in adsorption uptake of 4-AP was observed as the temperature increases from 25 °C to 45 °C. Maximum adsorption uptake (q_m) was found to be 106.11 mg/g at an optimum pH of 7.0 and 25 °C. Among various adsorption isotherm models tested, Langmuir Isotherm gave the best explanation with high R² values of experimental data. The pseudo-first-order model was found to explain the kinetics of adsorption well. The thermodynamic finding confirms the adsorption process was physical and exothermic. The adsorption of 4-AP was primarily governed by electrostatic interaction, hydrogen-bonding and π-π exchange mechanism. Because of the positive outcomes of the present research, we can use the PSASA as a cost-effective adsorbent for removing phenolic compounds.     

Direct synthesis of Poly(Ԑ-Caprolactone)-block-poly (glycidyl methacrylate) copolymer and its usage as a potential nano micelles carrier for hydrophobic drugs

Ring-opening (ROP) and enzymatic copolymerization (ECP) are among the most widely used approaches for synthesizing copolymers of polycaprolactone (PCL). It involves multiple-step reactions and the utilization of enzymes that make the process a lot more complicated, time consuming, and expensive. Atom transfer radical polymerization (ATRP) has been adopted to synthesize a novel amphiphilic copolymer in our study. The study presents a method to eliminate the ROP/ECP multiple steps in monomer polymerization thus making the process simpler and smoother. The synthesis of cationic polymer micelles copolymer of PCL-PGMA (polycaprolactone grafted poly glycidyl methacrylate) was carried out using direct functionalization of hydroxy group in crude PCL to achieve a higher degree of functionalization, i.e., 12.8% for macroinitiator. FTIR and ¹H-NMR confirmed the successful synthesis of the copolymer with better control over the molecular weight with a PDI (1.84). DSC and XRD results showed the reduction of crystallinity by 86.81%, making copolymer more compatible for drug delivery application. The synthesized copolymer was further converted to nano-micelles drug carrier having an average size of 96.08 ± 21.22 nm. The drug encapsulation efficiency achieved was 60.0 ± 1.7%, and nano-micelles rendered a slow and controlled release of naproxen with long-term storage stability.     

Supramolecular heterogeneity in β-turn forming synthetic tripeptides nucleated by isomers of fluorinated phenylalanine and aib as corner residues

The influences of fluorines in chemistry have emerged as a breakthrough in various arenas of bio-organic and medicinal chemistry. But its incorporation in β-turn design and its implications for supramolecular chemistry remains in a rudimentary stage. Inspired by the diversity displayed by the isomers of mono-fluorinated phenylalanine in biological sciences, here our effort is to modulate the solid state conformational analysis of three terminally protected synthetic tripeptides Boc-(Y)-F-Phe-Aib-Xaa-OMe, where (Y is (2)-F-Phe, Xaa; Leu in peptide I, (3)-F-Phe, Xaa; Leu in peptide II and (4)-F-Phe, Xaa; Ile in peptide III). Interestingly, all the three peptides display a conformational preference for β-turns, stabilized by 4→1 intramolecular hydrogen bonding. Our investigation further demonstrates that mere interchange of positions of fluorines in mono-fluorinated phenylalanine in peptides I–III introduces significant diversity in supramolecular chemistry. X-ray crystallography sheds some light at atomic resolution. Furthermore, this supramolecular heterogeneous behavior is evident from the morphologies obtained from the materials of all the three peptides grown from acetone to petroleum ether solution, studied by field emission scanning electron microscopy. Thus, these monofluorinated peptides I–III may serve as prominent candidates in understanding the structure and function of misfolded disease causing peptides like prion and Alzheimer's amyloid.     

Efficient and Green Syntheses of 12-Aryl-2,3,4,12-tetrahydrobenzo[b]xanthene-1,6,11-triones in Water and Task-Specific Ionic Liquid

Facile and convenient one-pot cascade/tandem approaches for the syntheses of privileged medicinal scaffolds, 12-aryl-2,3,4,12-tetrahydrobenzo[b]xanthene-1,6,11-trione derivatives, have been reported under extremely mild reaction conditions using a catalytic amount of H₂SO₄ in water or in the presence of the acidic ionic liquid bmim[HSO₄], which could be recycled.

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