A label-free impedimetric sensor based on αMnO2/tyrosinase hybrid for monitoring of diabetic foot ulcers

Among the various amino acids synthesized in our body, the concentration of L-tyrosine is found to be highly elevated in patients suffering from diabetic foot ulcer. Under chronic situations, the latter proves to be fatal and are often characterized by slow or non-healing wounds due to polymicrobial infections, whereby the patients may need to undergo amputation of lower limb(s). The conventional clinical diagnostic methods are costly and time consuming, in which case, the condition of patient(s) may deteriorate long before proper treatment commences. Herein, we report the designing and fabrication of a microfluidic enzymatic sensor for the detection of L-tyrosine by employing α-MnO
₂
/tyrosinase as receptor; immobilized on Au micro-electrodes. Electrochemical impedance spectroscopy using microfluidic platform from Micrux technologies has been employed for the estimation of L-tyrosine concentration using sample volume of approximately 2 μL. The impedance response was observed to be a linear function of tyrosine concentration within 5 nM - 500 μM with detection limit and sensitivity of 1.17 nM and 11.54 kΩ/nM/mm
²
respectively. The sensor was found to be selective only to tyrosine among various wound metabolites, and possessed a shelf life of ~ 1 month.