Design and development of ferrocene-containing chitosan-cografted-branched polyethylenimine redox conjugates for monitoring free flap failure after reconstructive surgery.

We reported a proof-of-concept study of developing an electrochemical biosensor for prolonged continuous monitoring free flap failure caused by vascular occlusion after reconstructive surgery. Ferrocene (Fc)-containing Chitosan-cografted-Branched Polyethylenimine redox conjugates (CHIT-Fc-co-BPEI-Fc) were used as pH-tuneable matrix to attach the target enzymes (glucose oxidase ≡ GOD and lactate oxidase ≡ LOD, respectively) to build up the corresponding GOD-sensor and LOD-sensor. The sensitivity of GOD-/LOD-sensor was found to be 2.89(±0.06)μA/mM and 2.95(±0.19)μA/mM with a limit of detection (LOD) of 0.047 mM and 0.172 mM, respectively. The sensor performance was further pre-clinically validated via rabbit study, which confirmed that the designed biosensors could electrochemically detect the changes of metabolite levels caused by flap failure within minutes. This sensor protocol is able to be fabricated as embedded biosensor for prolong continuous detection for clinical application/research.