Review—Advances in Biosensors for Detecting Human Epidermal Growth Receptor-2 Antigen in Serum for Breast Cancer

Breast cancer in women accounts for the second highest number of deaths worldwide. Among the various methods available, bio-sensing/immunosensing methods are comparatively more simple, rapid, sensitive, and specific. These biosensors detect the human epidermal growth factor receptor-2 (HER2) secreted in the serum of breast cancer patients at early stage of cancer. This review describes three types of biosensors depending on type of detection techniques used: Electrochemical techniques, including amperometric, voltametric, and impediametric; Piezoelectric techniques; and Optical techniques, including surface plasmon resonanance and fluorescence. These biosensors worked in the antibody concentration range, 1fg/ml to 500 ng/ml or 2 cells /ml with LOD ranging from 1fg/ml to 0.2ng/ml under the optimal assay conditions of pH (7.4 -7.5), temperature (25°C), and response time (10-30 min). The biosensors measured HER2 antigen level in sera of cancer patients, which was significantly higher than those in apparently healthy persons. The biosensors showed good storage stability (40-60 days) and regeneration ability. The merits and demerits of each class of immune-sensors are discussed. These biosensors could be miniaturized to make them portable to use at the bedside of patients.