Fig. 5.

On-chip meropenem calibration in 10 mM PBS using miLab and BiosensorX chips. a Antibody-free assay protocol consisting of four steps: 1. PBP-3-binding to surface, 2. casein blocking, 3. competitive binding of meropenem and biotinylated ampicillin, and 4. incubation of signal-generating molecule streptavidin-glucose oxidase. The on-chip assay calibration was performed using 4-plex BiosensorX where different concentrations of meropenem were incubated with the competitor into each immobilization area. Obtained calibration curves of BiosensorX (b) and BiosensorX together with miLab (c). Both calibration curves were analyzed using 4-parameter logistic fit, from which LODs of 22.5 ng ml⁻¹ for miLab and 28.6 ng ml⁻¹ for BiosensorX were calculated