CLiBE: A database of computed ligand binding energy for ligand-receptor complexes

10.1016/S0097-8485(02)00050-5Computers and Chemistry266661-666COCH

A novel quantitative approach to study dynamic anaerobic process at micro scale

International audienc

Kinetics and Mechanism of Nickel(II) Ion Biosorption by Immobilized Brown Laminaria Japonica

The biosorption of Ni(II) ions by brown Laminaria japonica algae immobilized in sodium alginate and glutin beads was investigated. The kinetics of Ni(H) ion biosorption within the immobilized L. japonica beads were described well by the pseudo-second-order model. The equilibrium curves describing Ni(II) ion biosorption by the immobilized algal beads were fitted by the Langmuir and Freundlich isotherm models. The maximum biosorption capacity for Ni(II) ions in the immobilized algae beads was found to be 39.43 mg/g. Fourier-transform infrared spectrometric analysis of powdered L. japonica before and after biosorption of Ni(II) ions indicated that several functional groups in the algal cells (-OH, -NH(2), -CH(2), -CH(3), -C=O, -N-H, -C-H, -C-O and -C=O) play an important role in the biosorption of Ni(II) ions by L. japonica

Automated stand-alone flow injection immunoanalysis system for the determination of cephalexin in milk

A fully automated stand-alone flow injection immunoanalysis (FIIA) device for the determination of cephalexin in milk is developed with a main focus on the investigation of the influence of the sample matrix. The system is based on principles of flow-through immunoassays and on sequential addition of the assay components to an immunoreactor. Protein G is immobilised on the surface of the immunoreactor serving as affinity matrix for the polyclonal anti-cephalexin antibodies. A cephalexin–alkaline phosphatase conjugate is mixed with the analyte-containing sample and binds in a competitve manner to the corresponding antibodies in the immunoreactor. After substrate addition enzymatically generated p-aminophenol is detected at a carbon electrode at +150 mV vs. Ag/AgCl. One assay cycle takes 16 min including regeneration of the immunoreactor. The large excess of protein G allows for more than 150 regenerations without significant loss of signal height. Due to the high specificity of the anti-cephalexin antibodies, other -lactam antibiotics like penicillin, amoxicillin and cloxacillin do not interfere in the measurements, even when added at 10 mg l–1. To deactivate alkaline phosphatase present in milk, samples are heat-treated for 3 min prior to measurements. Cephalexin recoveries from two milk samples are 90 and 110%. The detection limit in milk is 1 µg l–1 (mean relative standard deviation of 3%), less than the maximum residue level of 4 µg per kg milk fixed for some -lactam antibiotics in the European Union. The device is suitable for fast quantitative data generation from consecutively measured samples and thus adds to analytical screening methods

Fluorescence lifetime spectroscopy and imaging of nano-engineered glucose sensor microcapsules based on glucose/galactose-binding protein

We aimed to develop microsensors for eventual glucose monitoring in diabetes, based on fluorescence lifetime changes in glucose/galactose-binding protein (GBP) labelled with the environmentally sensitive fluorophore dye, badan. A mutant of GBP was labelled with badan near the binding site, the protein adsorbed to microparticles of CaCO3 as templates and encapsulated in alternating nano-layers of poly-l-lysine and heparin. We used fluorescence lifetime imaging (FLIM) with two-photon excitation and time-correlated single-photon counting to visualize the lifetime changes in the capsules. Addition of glucose increased the mean lifetime of GBP-badan by a maximum of 2 ns. Analysis of fluorescence decay curves was consistent with two GBP states, a short-lifetime component (0.8 ns), likely representing the open form of the protein with no bound glucose, and a long-lifetime component (3.1 ns) representing the closed form with bound glucose and where the lobes of GBP have closed round the dye creating a more hydrophobic environment. FLIM demonstrated that increasing glucose increased the fractional proportion of the long-lifetime component. We conclude that fluorescence lifetime-based glucose sensing using GBP encapsulated with nano-engineered layer-by-layer films is a glucose monitoring technology suitable for development in diabetes management