fig4
Figure 4. Passive/sensing release and electroactive controlled release of fluorescein. (A) Schematic representation of the core-shell structure. Shell compartment: passive release from the alginate layer. Core compartment: electroactive controlled release from PEDOT (quinoid structure, bottom). (B) Photograph of the core-shell structure loaded with fluorescein. (C) Concentration of fluorescein encapsulated in the volume of the alginate shell. The horizontal dashed line (red) indicates the fluorescein concentration in the polymerisation solution (1 mg mL-1). (D) Relationship between the amount of fluorescein encapsulated in the shell and the polymerisation charge applied to form the core-shell structure. Statistical analyses for (C and D) were made in triplicate over three different gold wire electrodes. Statistical significance was determined using one-way analysis of variance (ANOVA)/Tukey correction, n.s. is non-significant (P > 0.05), *P < 0.05 and **P < 0.001. (E) Passive release of fluorescein quantified by fluorescence (green, left axis) and total impedance change of the interface (blue, right axis). (F) Amount of fluorescein actively released from the core at different electric potentials. Each release experiment lasts 40 min. (G) Relationship between the amount of fluorescein encapsulated in the core and the polymerisation charge applied for core-shell structure formation. (H) Electroactive release of fluorescein under controlled conditions: ON (black, -1.2 V), OFF (green, +0.8 V), passive (red, OCP), P30 (blue, pulse for 30 s at -1.2 V), P8 (purple, pulse for 8 s at
