Electrokinetically driven fluidic transport in integrated three-dimensional microfluidic devices incorporating gold-coated nanocapillary array membranes

Electrokinetically driven fluid transport was evaluated within three-dimensional hybrid nanofluidic-microfluidic devices incorporating Au-coated nanocapillary array membranes (NCAMs). Gold NCAMs, prepared by electroless gold deposition on polymeric track-etched membranes, were susceptible to gas bubble formation if the interfacial potential difference exceeded approximately 2 V along the length of the gold region. Gold membranes were etched to yield 250 mum wide coated regions that overlap the intersection of two orthogonal microfluidic channels in order to minimize gas evolution. The kinetics of electrolysis of water at the opposing ends of the gold region was modeled and found to be in satisfactory agreement with experimental measurements of the onset of gas bubble formation. Conditions to achieve electrokinetic injection across Au-coated NCAMs were identified, with significant reproducible injections being possible for NCAMs modified with this relatively thin gold stripe. Continuous gold films led to suppressed injections and to a variety of ion enrichment/depletion effects in the microfluidic source channel. The suppression of injections was understood through finite element modeling which revealed the presence of a significant electrophoretic velocity component in opposition to electroosmotic flow at the edge of the Au-dielectric regions.     

Solid phase synthesis of a redox delivery system with the aim of targeting peptides into the brain

A solid phase approach for the preparation of peptides attached to a redox chemical delivery system derived from stable annulated NADH models is reported. The synthesis starts with the grafting on a Merrifield resin of quinoline 4b, precursor of the redox carrier. From the resulting quinoline supported resin 4d, the stepwise SPPS of both octapeptide OP (RPGLLDLK) and octadecaneuropeptide ODN (QATVGDVNTDRPGLLDLK), two neuropeptides exhibiting anorexigenic effects, was successfully achieved by conventional methods. Quaternization of the quinoline moiety prior to cleavage of the modified OP and ODN peptides from the resin, led to the expected quinolinium salt 8a and 8b respectively linked to OP or ODN peptides. Finally, the reduction with NaBH4 monitored by UV-vis, provided the desired annulated NADH models as peptides carriers with either the OP (11a,b) or ODN (12a,b) moiety.