Assessing Wound Healing\nin Vivo Using a Dual-Function\nPhosphorescent Probe Sensitive to Tissue Oxygenation and Regenerating\nCollagen

Levels of tissue oxygenation and collagen regeneration\nare critical\nindicators in the early evaluation of wound healing. Traditionally,\nthese factors have been assessed using separate instruments and different\nmethodologies. Here, we adopt the spatially averaged phosphorescence\nlifetime approach using Re<sup>I</sup>-diimine complexes (Re<sup>I</sup>-probe) to enable simultaneous quantification of these two critical\nfactors in healing wounds. The topically applied, biocompatible Re<sup>I</sup>-probe penetrates wound tissue effectively and selectively\nbinds to collagen fibers. During collagen regeneration, the phosphorescence\nlifetimes of the collagen-bound probe significantly extend from an\ninitial range of 4.5–6.5 μs on day 0 to 5.5–8.5\nμs by day 7. Concurrently, unbound probes in the tissue interstitial\nspaces exhibit a phosphorescence lifetime of 4.5–5.2 μs,\nrevealing the oxygenation states. Using phosphorescence lifetime imaging\nmicroscopy (PLIM) and a frequency domain phosphorescence lifetime\nmeasurement (FD-PLM) system, we validated the dual-functionality of\nthis Re<sup>I</sup>-probe in differentiating healing stages in chronic\nwounds. With its noninvasive, quantitative measurement capabilities\nfor cutaneous wounds, this Re<sup>I</sup>-probe-based approach offers\npromising potential for early wound healing diagnosis.