Development and evaluation of a new affiprobe that targets HER 3 positive cells using protein engineering

Engineered affiprobes that detect a specific target by generating a target-dependent signal, play an important role in biomedical sciences such as breast cancer monitoring. In this study, a new bioluminescence affiprobe consisting of an HER3-binding affibody and a bioluminescent protein, C-SRLc8, a thermostable variant of Renilla luciferase has been developed. The bioluminescent affibody, called C-SRLuc8‒Z₀₈₆₉₉ was expressed in the Escherichia coli and purified by affinity chromatography. The suitability of the new affiprobe to detected HER3 positive cells was evaluated. It was found that the new affiprobe allowed the detection of HER3 expressing cells with a detection limit of 14578 cells per 200 μl assay volume and a working range of 14000-50000 cells. The new affiprobe can be used for detecting, studying and monitoring the HER3-expressing cells using a luminometer in fast and inexpensive assays.