Glucose-Sensitive Nanoassemblies Comprising Affinity-Binding Complexes Trapped in Fuzzy Microshells

A new design for glucose monitoring with "smart" materials based on self assembly, competitive binding, and resonance energy transfer (RET) is presented. The basic transduction principle is changing RET efficiency from fluorescein isothiocyanate (FITC) to tetramethylrhodamine isothiocyanate (TRITC), as FITC-dextran is displaced from TRITC-Concanavalin A (Con A) with the addition of glucose. Nanoscale fabrication by self-assembly of Con A/dextran into multilayer films, followed by polymer multilayers. The advantages of this approach include physical localization and separation of sensing molecules from the environment via entrapment of the biosensorelements in a semi-permeable polymeric shell, and only functional molecules are included in the sensors. To realize these nanostructures, dissolvable resin microparticles were coated with FITC-dextran+TRITC-Con A multilayers, followed by polyelectrolyte multilayers, and the core particles were then dissolved to yield hollow capsules. The nanoassembly process was studied using microbalance mass measurements, fluorescence spectroscopy, confocal fluorescence microscopy, and zeta-potential measurements. The key findings are that the specific binding between Con A and dextran can be used to deposit ultrathin multilayer films, and these exhibit changing RET in response to glucose. Fluorescence spectra of a microcapsules exhibited a linear, glucose-specific, 27% increase in the relative fluorescence of FITC over the 0-1800 mg/dL range. These findings demonstrate the feasibility of using self-assembled microcapsules as optical glucose sensors, and serve as a basis for work toward better understanding the properties of these novel materials.     

1,2,3‐Triazole derivatives of 3‐ferrocenylidene‐2‐oxindole: Synthesis,characterization, electrochemical and antimicrobial evaluation

A series of bioactive, triazole‐linked benzyl, aryl, sugar and aliphatic conjugates of 3‐ferrocenylidene‐oxindole have been synthesized. A facile 1,3‐dipolar‐Huisgen coupling reaction of the respective azides with the 3‐ferrocenylidene‐oxindole N‐propargyl moiety ( 3 ) gave the corresponding conjugates ( 5a–n ). All the newly synthesized compounds ( 5a–n ) were characterized by ¹H‐NMR, ¹³C‐NMR, HRMS, Fourier transform‐infrared spectroscopy and elemental analysis. The UV–Vis and electrochemical studies of these compounds were performed in dimethylsulfoxide solutions. The structure of compound ( 3 ) was determined by single crystal X‐ray diffraction study. These compounds exhibited moderate to good antimicrobial activity against Gram‐positive and Gram‐negative strains.     

Surface cationization of cellulose to enhance durable antibacterial finish in phytosynthesized silver nanoparticle treated cotton fabric

Cellulose - Elimination of disease-causing bacteria from cotton fabrics is critically important to control several bacteria-mediated infections in humans. Antibacterial nanoparticles, particularly...     

Acetohydroxamic acid: a new reagent for efficient synthesis of nitriles directly from aldehydes using Bi(OTf)3 as the catalyst

An efficient method for the preparation of nitriles directly from aldehydes by reaction with AHA using Bi(OTf)₃ as the catalyst is described. Bi(OTf)₃ is shown to be an efficient catalyst also for the conversion of aldoximes into nitriles.     

Efficient and chemoselective acetalization and thioacetalization of carbonyls and subsequent deprotection using InF3 as a reusable catalyst

An efficient and chemoselective method for preparation of acetals and dithioacetals of aldehydes and their deprotection under catalysis of InF₃ is described.     

Synthesis and Comparative Study of Nano-TiO2 Over Degussa P-25 in Disinfection of Water

Nanostructured TiO₂ crystals were synthesized by gel to crystalline conversion. The crystals obtained were anatase form of titania averaging in 30 nm particles with an intrinsic band gap of 3.1 eV. The photocatalytic behavior was evaluated for the bactericidal effect in water, contaminated with the indicator organism Escherichia coli. The 100% photoinactivation of E. coli was achieved within 60 min with suspended nano-TiO₂. The catalytic activity of synthesized nanosample was observed to be 2.6 times more than that of commercial TiO₂ sample referred to as Degussa P-25. The photoinactivation of E. coli was tested with irradiation source of different wavelengths to substantiate the influence of particle size and nano crystallinity on electronic band structure. The photoactivity of nano titania enhanced to 1.625 times when the source of irradiation shifted from 360 to 400 nm while Degussa P-25 showed no change.     

Structure and photocatalytic activity of Ti1?X MX O2 (M = Zr, Co and Mo) synthesized by pulverized solid state technique

A set of transition metal doped nanosized TiO₂ particles with anatase structure were synthesized by the pulverization method and their ability to photocatalytically degrade the dye Alizarin Red S was investigated. Characterization of the Zr-, Co- and Mo-doped photocatalysts was conducted with the aid of XRD, SEM, EDX, TEM, BET and spectral analysis. X-ray diffraction patterns did not reflect the appearance of any peaks due to dopants, however dopants were observed in SEM-EDX analysis. Particle sizes were in the range of 25 nm as per TEM and XRD analysis. Upon doping, a prominent decrease in surface area was observed. The percentage composition of each of the dopants was confirmed by EDX analysis. Doped samples depicted many mid-bands in the Kubelka Munk plots due to d-d transition of dopants. Experiments were conducted to compare the photocatalytic activity under identical UV and solar light exposure. Zr-doped TiO₂ at the molecular scale exhibited better photocatalytic activity in degradation of Alizarin, with a lower band-gap energy that can respond to visible light. However, Co- and Mo-doped TiO₂ appeared to suppress the photoactivity. A rise in the number of mid-bands causing effective separation or recombination of charge carriers strongly influences the rate of the degradation process.      

Paliperidone-Loaded Self-Emulsifying Drug Delivery Systems (SEDDS) for Improved Oral Delivery

The present research is aimed to improve the oral delivery of paliperidone by loading into self-emulsifying drug delivery systems (SEDDS). Oleic acid, Tween 80, and capmul MCM L8 were selected as oil, surfactant, and co-surfactant, respectively and phase diagram was constructed and the region was identified for the formation of SEDDS. The stable formulations were analyzed for globule size, robustness to dilution and in vitro drug release. The globule size of all the formulations was found to be in the range of 205 to 310 nm with good size uniformity and seems to be dependent on the proportion of oil in SEEDS formulation. The optimized formulation (F3) has been adsorbed onto neusilin and characterized. The DSC and XRD spectra unravel the presence of molecular state of paliperidone in solid SEDDS. The in vitro dissolution study indicates improved dissolution characteristics with higher dissolution efficiency for solid SEDDS (SEDDS-N) compared to pure drug. Further ex vivo permeation studies carried out using rat intestine suggest a 2- to 3-fold improvement in permeation for SEDDS compared to pure drug. In conclusion, SEDDS prove to be potential carriers for improved oral delivery of paliperidone.     

A Facile Synthesis of Novel 9-Methyl[1, 2, 3]Selenadiazoles[4, 5-b]Quinoline and 9-Methyl[1, 2, 3]Thiadiazole[4, 5-b]Quinoline as a New Class of Antimicrobial Agents

2-chloro-4-methyl quinoline 2 on condensation with semicarbazide hydrochloride gave its semicarbazone. This on reaction with SeO ₂ and SOCl₂ yielded a new class of novel selenadiazoles 4 and thiadiazoles 5, respectively. The structure of all the compounds were elucidated on the basis of elemental analysis, IR, ¹ H NMR, and the mass spectral data. Some derivatives of 9-methyl[1, 2, 3]selenadiazole[4, 5-b] quinoline and 9-methyl[1, 2, 3]thiadiazole [4, 5-b]quinoline have been screened for antimicrobial activities.     

Quantification of glycopeptides by multiple reaction monitoring liquid chromatography/tandem mass spectrometry

Protein glycosylation has a major influence on functions of proteins. Studies have shown that aberrations in glycosylation are indicative of disease conditions. This has prompted major research activities for comparative studies of glycoproteins in biological samples. Multiple reaction monitoring (MRM) is a highly sensitive technique which has been recently explored for quantitative proteomics. In this work, MRM was adopted for quantification of glycopeptides derived from both model glycoproteins and depleted human blood serum using glycan oxonium ions as transitions. The utilization of oxonium ions aids in identifying the different types of glycans bound to peptide backbones. MRM experiments were optimized by evaluating different parameters that have a major influence on quantification of glycopeptides, which include MRM time segments, number of transitions, and normalized collision energies. The results indicate that oxonium ions could be adopted for the characterization and quantification of glycopeptides in general, eliminating the need to select specific transitions for individual precursor ions. Also, the specificity increased with the number of transitions and a more sensitive analysis can be obtained by providing specific time segments. This approach can be applied to comparative and quantitative studies of glycopeptides in biological samples as illustrated for the case of depleted blood serum sample. Copyright © 2012 John Wiley & Sons, Ltd.