(A) Preparation and detection procedures for the MMP-2 immunosensor. Reprinted from [99], Copyright 2013, with permission from Elsevier; (B) Typical DPVs corresponding to MMP-2 concentrations from a to j (0, 0.0005, 0.005, 0.02, 0.05, 0.25, 1.0, 5.0, 10.0 and 50.0 ng mL−1) in PBS + 4 mM H2O2, and corresponding calibration curve; (C) The different steps involved in the construction of the adiponectin (APN) immunosensor using a metallocomplex polymer (CMC) and RGO on a screen-printed carbon electrode; (D) Corresponding calibration plot. Reprinted from [101], Copyright 2016, with permission from Elsevier.