  Simple and low-cost biosensing solutions are suitable for point-of-care
applications aiming to overcome the gap between scientific concepts and
technological production. To compete with sensitivity and selectivity of golden
standards, such as liquid chromatography, the functionalization of biosensors
is continuously optimized to enhance the signal and improve their performance,
often leading to complex chemical assay development. In this research, the
efforts are made on optimizing the methodology for electrochemical reduction of
graphene oxide to produce thin film-modified gold electrodes. Under the
employed specific conditions, 20 cycles of cyclic voltammetry (CV) are shown to
be optimal for superior electrical activation of graphene oxide into
electrochemically reduced graphene oxide (ERGO). This platform is further used
to develop a matrix metalloproteinase 2 (MMP-2) biosensor, where specific
anti-MMP2 aptamers are utilized as a biorecognition element. MMP-2 is a protein
which is typically overexpressed in tumor tissues, with important roles in
tumor invasion, metastasis as well as in tumor angiogenesis. Based on
impedimetric measurements, we were able to detect as low as 3.32 pg/mL of MMP-2
in PBS with a dynamic range of 10 pg/mL - 10 ng/mL. Besides high specificity,
ERGO-based aptasensor showed a potential of reuse due to demonstrated
successful signal restoration after experimental detection of MMP-2.
