Dispersion of crystallites of the metal substrate during the electropolymerization of 2-hydroxy-3-aminophenazine (HAPh) on Au: effect of Au crystallites on the kinetics and mechanism of charge-transfer reactions between the polymer and redox species in electrolyte

The electrochemical polymerization of 2-hydroxy-3-aminophenazine (HAPh) has been studied in aqueous perchloric acid solutions. Under potential cycling the polymerization reaction is accompanied by electrodissolution/electrodeposition of the Au substrate onto which the polymer is deposited. TEM observations have revealed two kinds of crystalline grains in the pHAPh polymer film. The first kind consists of spherical grains of pure gold which are randomly oriented in the polymer matrix. The second kind consists of oriented well-shaped crystals of unknown composition, but most probably crystals of an intermediate Au(III) complex. The dispersed Au crystallites affect the kinetics and mechanism of charge-transfer reactions between the polymer and redox species in electrolyte, such as dihydroxybenzenes and hydrazine, as well as their permeability and incorporation into the polymer film.     

Intravital sidestream dark-field (SDF) imaging is used in a rabbit model for continuous noninvasive monitoring and quantification of mucosal capillary regeneration during wound healing in the oral cavity: A pilot study

Angiogenesis and tissue revascularization are essential for proper postoperative tissue repair and regeneration. The aim of this investigation was to develop an animal model to study postoperative microcirculatory vascularization continuously in time following oral surgery. Five female specific-pathogen free New Zealand White rabbits with a mean body weight of 3.0 ± 0.4 kg were used in this study. In all animals a palatine mucosal flap was raised, suspended for 30 min, and then repositioned for subsequent postoperative assessment of capillary regeneration. Noninvasive mucosal capillary density measurements were performed preoperatively using sidestream dark-field (SDF) imaging and repeated measurements were collected immediately postoperatively and on days 2, 4, 7, 9, 11, 14, and 21. In addition, whole blood count (Hb, RBC, WBC, PLT) and body weight were monitored in all animals at each time point. The greatest increase in mucosal capillary regeneration occurred in the early healing period on days 4, 7, 9, and recovery to baseline was achieved by postoperative day 11. Comparisons between preoperative versus postoperative, and prospective mean capillary density measurements on days 2, 4, 7, and 9 were statistically significant (P < 0.05). No significant difference in capillary density development at each time point was observed between the five animals. In all animals, whole blood count and body weight remained stable and revealed no statistically significant changes. However, only on day 21 a statistically significant increase in body weight was found (P < 0.05). The application of SDF imaging in the present wound model enabled continuous daily inspection of the oral microcirculation following surgery in vivo to pursue the kinetics of microcirculatory regeneration in time. We expect SDF imaging and our wound model to contribute to new insights into the kinetics of wound vascularization under various pathophysiological conditions and drug intervention studies.