An enzyme-modified capillary as a platform for simultaneous fluorometric detection of d-glucose and l- lactate

•A method for forming patterned phospholipid monolayers on the inner wall of a glass capillary was developed.•The usefulness of the patterned phospholipid monolayers as an adsorbent material of lactate dehydrogenase (LDH) and glucose dehydrogenase (GDH) is demonstrated.•An enzyme-modified capillary enabled us to simultaneous quantification of D-glucose and L-lactate in human serum. The preparation of a glass capillary pattered with lipid layers on which lactate dehydrogenase (LDH) and glucose dehydrogenase (GDH) were regionally adsorbed and its application for simultaneous detection of d-glucose and l-lactate in human serum is described. A lipid layer was formed on the surface of BSA-unabsorbed octadecyltrichlorosilane (OTS) inner wall of a glass capillary. The electrostatic charge of the lipid layer was a key factor for adsorbing the enzymes on the lipid layer. The fluorescence intensities were observed at each enzyme site in the presence of diaphorase (DIA), β-nicotinamide-adenine dinucleotide oxidized (NAD), resazurin, d-glucose and l-lactate. The fluorescence intensities at each enzyme site increased with an increase in the concentration of d-glucose and l-lactate=with the detection limits of 32 μM and 4.9 μM, respectively.