Figure 22.

(A) Schematic illustration of the fluorescent hydrogel fiber designed for long-term in vivo glucose monitoring. The fiber can be injected into subcutaneous tissues. The implanted fiber remains at the implantation site for a long period and transmits fluorescent signals transdermally depending on blood glucose concentration. The implanted fiber can be easily removed from the implantation site after use. (B) Fluorescent hydrogel fibers in a glass vial with a 50% glucose solution. The fibers are excited by ultraviolet light. The fluorescent image indicates that the glucose-responsive monomer is immobilized within the hydrogel fibers. (C) Inflammation indices of the mouse ears with the fibers one month after implantation. Inflammation was evaluated based on reddening, swelling and scab formation for a month. The inflammation index was obtained by summing the reddening, swelling, and scab formation scores. If the ear skin showed any reddening, reddening scores 1 point; similarly, swelling and scab formation were each also scored 1 point. PEG-bonded PAM induced less inflammation than PAM only. (D) Numbers of mice showing transdermal transmission of fiber fluorescence [67].