The effects of detergents on squid giant axon action and resting potentials as well as membrane conductances in the voltage clamp have been studied. Anionic detergents (sodium lauryl sulfate, 0.1 to 1.0 mM; dimethyl benzene sulfonate, 1 to 20 mM, pH 7.6) cause a temporary increase and a later decrease of action potential height and the value of the resting potential. Cationic detergent (cetyl t...

Electrostatics play a key role in biomolecular assembly. Oppositely charged biomolecules, for instance, can be coassembled into functional units, such as DNA and histone proteins into nucleosomes and actin-binding protein complexes into cytoskeleton components, at appropriate ionic conditions. These cationic-anionic coassemblies often have surface charge heterogeneities that result from the del...

The synthesis and evaluation of a new class of cationic iodinated contrast agents for the imaging of cartilage using computed tomography (CT) are described. In direct comparisons with anionic contrast agents, the cationic contrast agents afforded higher equilibrium concentrations in the articular cartilage of ex vivo rabbit femurs and thus greater imaging sensitivity. Variations in CT intensity...

We investigate the complexation of ampholytic poly(N-isopropylacylamide)-block-poly- (L-glutamic acid)-block-poly(L-lysine) (PNiPAM-b-PLG-b-PLLys) triblock copolymers and PNiPAM-block-(PLG-co-PLLys) diblock copolymers with counter charged anionic and cationic surfactants. Both triblock and diblock copolymers are able to selectively form complexes through either L-glutamic acid-cationic surfacta...

An electrostatic complexation of liposomes, composed of anionic palmitoyloleoyl phosphatidylserine (POPS ) and zwitterionic dioleoylphophatidylcholine (DOPC), with bilayer vesicles composed of cationic poly(L-lysine)-b-poly(L-leucine) block copolypeptides has been investigated. The complexation was characterized by several physicochemical methods with the following main conclusions: (a) all add...

Surfactants such as didodecyldimethyl ammonium bromide (DDAB) and 1,2-dilauroyl-sn-phosphatidylcholine (DLPC) form bilayers at the walls of bare silica capillaries. Once formed, these bilayers are stable in the absence of surfactant in the buffer. DDAB provides a cationic bilayer coating which yields a strong reversed EOF and is effective for separation of cationic proteins. DLPC provides a zwi...

The performance of CE coupled on-line to MS via a sheathless porous tip sprayer was evaluated for anionic metabolic profiling. A representative metabolite mixture and biological samples were used for the evaluation of various analytical parameters, such as peak efficiency (plate numbers), migration time and peak area repeatability, and LODs. The BGE, i.e. 10% acetic acid (pH 2.2), previously us...