Implanted biofuel cell operating in a living snail

Implantable biofuel cells have been suggested as sustainable micropower sources operating in living organisms, but such bioelectronic systems are still exotic and very challenging to design. Very few examples of abiotic and enzyme-based biofuel cells operating in animals in vivo have been reported. Implantation of biocatalytic electrodes and extraction of electrical power from small living creatures is even more difficult and has not been achieved to date. Here we report on the first implanted biofuel cell continuously operating in a snail and producing electrical power over a long period of time using physiologically produced glucose as a fuel. The "electrified" snail, being a biotechnological living "device", was able to regenerate glucose consumed by biocatalytic electrodes, upon appropriate feeding and relaxing, and then produce a new "portion" of electrical energy. The snail with the implanted biofuel cell will be able to operate in a natural environment, producing sustainable electrical micropower for activating various bioelectronic devices.     

Synthesis and chemistry of some pyridazine nucleosides related to certain 5-substituted pyrimidine nucleosides

Condensation of 3,4-dichloro-6-[(trimethylsilyl)oxy] pyridazine ( 3 ) with 1-O-acetyl-2,3,5-tri-O-benzoyl-β- D -ribofuranose ( 4 ), by the stannic chloride catalyzed procedure, has furnished 3,4-dichloro-1-(2,3,5-tri-O-benzoyl-β- D -ribofuranosyl) pyridazin-6-one ( 5 ). Nucleophilic displacement of the chloro groups and removal of the benzoyl blocking groups from 5 has furnished 3-chloro-4-methoxy-, 3,4-dimethoxy-, 4-amino-3-chloro-, 3-chloro-4-methylamino-, 3-chloro-4-hydroxy-, and 4-hydroxy-3-methoxy-1-β- D -ribofuranosylpyridazin-6-one. An unusual reaction of 5 with dimethylamine is reported. Condensation of 4,5-dichloro-3-nitro-6-[(trimethylsilyl)oxy]pyridazine with 4 yielded 4,5-dichloro-3-nitro-1-(2,3,5-tri-O-benzoyl-β- D -ribofuranosyl)pyridazin-6-one ( 24 ). Nucleophilic displacement of the aromatic nitro groups from 24 is discussed. Condensation of 3 with 3,5-di-O-p-toluoyl 2-deoxy- D -erythro-pentofuranosyl chloride ( 28 ) afforded an α, β mixture of 2-deoxy nucleosides. The synthesis of certain 3-substituted pyridazine 2′-deoxy necleosides are reported.     

Rapid colorimetric detection of antibody-epitope recognition at a biomimetic membrane interface.

Biomolecular recognition of antigens and epitopes by antibodies is a fundamental event in the initiation of immune response and plays a central role in a variety of biochemical processes. Peptide binding requires, in many cases, presentation of the peptides at interfaces, such as protein surfaces, cellular membranes, and synthetic polymer surfaces. We describe a novel molecular system in which interactions between antibodies and peptide epitopes displayed at a biomimetic membrane interface can be detected through induction of visible, rapid color transitions. The colorimetric assembly consists of a phospholipid/polydiacetylene matrix anchoring a hydrophobic peptide displaying the epitope at its N-terminus. The colorimetric transitions observed in the assembly, corresponding to perturbation of the polydiacetylene framework, are induced only upon recognition of the displayed epitope by its specific antibody present in the aqueous solution. Significantly, the color changes occur after a single mixing step, without further chemical reactions or enzymatic processing. The new molecular system could be utilized for studying antigen-antibody interactions and peptide-protein recognition, epitope mapping, and rapid screening of biological and chemical libraries.     

Excess thermodynamic properties of the 2-propanol + dichloromethane system at 25°C

Densities, viscosities, enthalpies, vapor-liquid equilibria, and surface tensions were determined at 25°C for the 2-propanol+dichloromethane system. From the experimental results excess volumes, viscosities, enthalpies, Gibbs energies, and excess surface tensions were calculated. An attempt has been made to explain the observed deviations from ideal behavior on the basis of intermolecular interactions.     

Protein release from interpenetrating polymer network hydrogels triggered by endogenous biomarkers

A biocompatible drug delivery system with a high-sensitive stimuli-responsive behavior is reported. Calcium alginate hydrogels interpenetrated with polyvinyl alcohol–diboronate polymer network (IPN) effectively respond to the presence of hydrogen peroxide through oxidative degradation of boronate esters. The degradation of the IPN entails the reopening of the original alginate pores, resulting in a 5–9 times increase in release rates of encapsulated proteins with molecular masses ranging from 16.7 to 66 kDa. The release can be triggered by hydrogen peroxide concentrations as low as 50 μM in the bulk solution. Alternatively, hydrogen peroxide can also be generated inside the hydrogels by incorporation of oxidase enzymes in the presence of their substrates, such as lactate, glucose, or hypoxanthine, which can serve as biomarkers of certain physiological disorders.     

Amplified DNA sensing and immunosensing by the rotation of functional magnetic particles

Amplified chemiluminescent detection of DNA-complementary DNA or of antigen-antibody interactions is accomplished in the presence of rotating functionalized magnetic particles.     

Magnetic control of electrocatalytic and bioelectrocatalytic processes

Bioelectronics is a rapidly progressing interdisciplinary research field that has important implications for the development of biosensors, biofuel cells, biomaterial-based computers, and bioelectronic devices. Magneto-controlled molecular electronics and bioelectronics are new topics that examine the effect of an external magnetic field on electrocatalytic and bioelectrocatalytic processes of functionalized magnetic particles associated with electrodes. In this article we describe the progress in the developments of magneto-switchable electrocatalytic and bioelectrocatalytic transformations, and the effects of the rotation of the magnetic particles on the electrocatalytic and bioelectrocatalytic processes are discussed. Finally, the implications of the results on the development of biosensors, amplified immunosensors, and DNA sensors are described.     

The arrangement of first- and second-shell water molecules in trivalent aluminum complexes: results from density functional theory and structural crystallography

The structural and energetic features of a variety of gas-phase aluminum ion hydrates containing up to 18 water molecules have been studied computationally using density functional theory. Comparisons are made with experimental data from neutron diffraction studies of aluminum-containing crystal structures listed in the Cambridge Structural Database. Computational studies indicate that the hexahydrated structure Al[H(2)O](6)(3+) (with symmetry T(h)()), in which all six water molecules are located in the innermost coordination shell, is lower in energy than that of Al[H(2)O](5)(3+).[H(2)O], where only five water molecules are in the inner shell and one water molecule is in the second shell. The analogous complex with four water molecules in the inner shell and two in the outer shell undergoes spontaneous proton transfer during the optimization to give [Al[H(2)O](2)[OH](2)](+).[H(3)O(+)](2), which is lower in energy than Al[H(2)O](6)(3+); this finding of H(3)O(+) is consistent with the acidity of concentrated Al(3+) solutions. Since, however, Al[H(2)O](6)(3+) is detected in solutions of Al(3+), additional water molecules are presumed to stabilize the hexa-aquo Al(3+) cation. Three models of a trivalent aluminum ion complex surrounded by a total of 18 water molecules arranged in a first shell containing 6 water molecules and a second shell of 12 water molecules are discussed. We find that a model with S(6) symmetry for which the Al[H(2)O](6)(3+) unit remains essentially octahedral and participates in an integrated hydrogen bonded network with the 12 outer-shell water molecules is lowest in energy. Interactions between the 12 second-shell water molecules and the trivalent aluminum ion in Al[H(2)O](6)(3+) do not appear to be sufficiently strong to orient the dipole moments of these second-shell water molecules toward the Al(3+) ion.