A Simple and Low-Cost Electrochemical Immunosensor for Ultrasensitive Determination of Calreticulin Biomarker in Human Serum.

An early on time detection of breast cancer significantly affects the treatment process and outcome. Herein, a new label-free impedimetric biosensor is developed to determine the lowest change in the level of calreticulin (CALR), which is a new biomarker of breast carcinoma. The proposed immunosensor is fabricated by using reduced graphene oxide/amino substituted polypyrrole polymer (rGO-PPyNH 2 ) nanocomposite modified disposable electrode. The anti-CALR antibodies are first attached on the rGO-PPyNH 2 nanocomposite coated electrode through glutaraldehyde crosslinking; the CALR antigens are then immobilized with the addition of CALR antigens to form an immunocomplex on the sensing surface. This immunocomplex induces considerably larger interfacial electron transport resistance (R ct ). The variation in the R ct has a linear relationship with CALR level in the detection range of 0.025 to 75 pg mL -1 , with a detection limit of 10.4 fg mL -1 . The suggested biosensor shows high selectivity to CALR, good storage stability (at least 5 weeks) and suitable reproducibility results as shown in quality control chart. The designed immunosensor is utilized to analyze CALR levels in human sera with satisfying results. This immunosensor provides a novel way for the clinical determination of CALR and other cancer biological markers.