Modulation of Electroosmotic Flow through Skin: Effect of Poly(Amidoamine) Dendrimers

The objective of this work is to evaluate the effect of polyamidoamine (PAMAM) dendrimers on electroosmotic flow (EOF) through skin. The effect of size and concentration of dendrimer was studied, using generation 1, 4 and 7 dendrimer (G1, G4 and G7, respectively). As a marker molecule for the direction and magnitude of EOF, a neutral molecule, acetoaminophen (AAP) was used. The visualization of dendrimer permeation into the current conducting pore (CCP) of skin was made using G4–fluorescein isothiocyanate (FITC) conjugate and confocal microscopy. Without dendrimer, anodal flux of AAP was much higher than cathodal or passive flux. When G1 dendrimer was added, anodal flux decreased, presumably due to the decrease in EOF by the association of G1 dendrimer with net negative charge in CCP. As the generation increased, larger decrease in anodal flux was observed, and the direction of EOF was reversed. Small amount of methanol used for the preparation of dendrimer solution also contributed to the decrease in anodal flux of AAP. Cross-sectional view perpendicular to the skin surface by confocal laser scanning microscope (CLSM) study showed that G4 dendrimer-FITC conjugate (G4-FITC) can penetrate into the viable epidermis and dermis under anodal current. The permeation route seemed to be localized on hair follicle region. These results suggest that PAMAM dendrimers can permeate into CCP and change the magnitude and direction of EOF. Overall, we obtained a better understanding on the mechanistic insights into the electroosmosis phenomena and its role on flux during iontophoresis.

Preparation and Application of Capillary Columns Modified by Polyacrylamide with Different Groups / 分析化学

Allyamine or sodium vinyl sulfate was added into the solutions of acrylamide and N,N′-methylenebisacrylamide to make mixed monomer solutions. These solutions were respectively introduced in methacrylsiloxane-modifidied capillaries. In situ polymerization was initiated by thermally induced radicals. A polymer layer was chemically bonded to the inner wall, resulting in valently modified capillary columns. By altering the addition amounts of allyamine or sodium vinyl sulfate, differently charged polymeric layers were obtained. Five columns were prepared. The result indicated that columns modified with polymers containing amino groups were advantageous over those containing sulphonic acid groups or none. Further comparison revealed that the columns modified with a solution containing 0.15 mol/L acrylamide, 0.03 mol/L N,N′-methylenebisacrylamide and more than 1 mol/L allylamine exhibited good resolution. It is convenient to adjust electroosmotic flows(EOFs) in the columns by this way. In the meantime unspecific protein adsorption was efficiently depressed. When subjected) to zone electrophoresis of proteins from chicken egg white, the column showed high resolution and good reproducibility.