fig5

Figure 5. Enzyme-based lactate sensing mechanisms and applications. (A) Enzymatic reaction scheme for lactate sensing; (B) Lactazyme-immobilized MN lactate sensor; (C) Current response as a function of acetate-cellulose coating thickness; (D) Mechanism of ISF-based lactate sensing. H₂O₂ generated by lactate oxidase undergoes spontaneous redox cycle with PB, producing a detectable current; (E) Effect of a hydrated polymer layer on MN surfaces. (B and C) Reproduced with permission Copyright 2023, ACS Sensors^[182]. (D and E) Reproduced with permission Copyright 2024, ACS Sensors^[127]. MN: Microneedle; ISF: interstitial fluid; PB: Prussian blue; ADP: adenosine diphosphate; NAD+: nicotinamide adenine dinucleotide (oxidized form); NADH: nicotinamide adenine dinucleotide (reduced form); LOx: lactate oxidase; CHI: chitosan; PB_RED: reduced Prussian blue; PB_OX: oxidized Prussian blue; Lac: lactate; DIFF. MEMB: diffusion membrane.