Levels of tissue oxygenation and collagen regeneration are critical indicators in the early evaluation of wound healing. Traditionally, these factors have been assessed using separate instruments and different methodologies. Here, we adopt the spatially averaged phosphorescence lifetime approach using ReI-diimine complexes (ReI-probe) to enable simultaneous quantification of these two critical factors in healing wounds. The topically applied, biocompatible ReI-probe penetrates wound tissue effectively and selectively binds to collagen fibers. During collagen regeneration, the phosphorescence lifetimes of the collagen-bound probe significantly extend from an initial range of 4.5-6.5 μs on day 0 to 5.5-8.5 μs by day 7. Concurrently, unbound probes in the tissue interstitial spaces exhibit a phosphorescence lifetime of 4.5-5.2 μs, revealing the oxygenation states. Using phosphorescence lifetime imaging microscopy (PLIM) and a frequency domain phosphorescence lifetime measurement (FD-PLM) system, we validated the dual-functionality of this ReI-probe in differentiating healing stages in chronic wounds. With its noninvasive, quantitative measurement capabilities for cutaneous wounds, this ReI-probe-based approach offers promising potential for early wound healing diagnosis.
Keywords: Collagen regeneration; Phosphorescence lifetime imaging; Phosphorescence probe; Wound healing; Wound oxygenation.