Simple strategy for single-chain fragment antibody-conjugated probe construction

Aims: A combination of biomarker and instrument technology diagnosis methods, especially antigen-targeted imaging methods, is required to increase the accuracy of the diagnosis of cancer. Currently, the targeting efficiency is limited by the conjugation methods used for the conjugation of antibodies and imaging materials. Here, a simple strategy for the conjugation of a probe and a single-chain fragment antibody (scFv) that does not change the characteristics of the antibody was shown. Main methods: An ScFv was conjugated with superparamagnetic iron oxide (SPIO) or indocyanine green (ICG) via a linker by utilizing the reaction between cysteine and maleimide. The characterization of the probe was performed by flow cytometry, confocal imaging, optical imaging and magnetic resonance imaging (MRI). Key findings: After conjugation, the scFv retained high affinity, antigen specificity, and strong internalization ability. The application of the conjugated probe was also confirmed by optical imaging and MRI. Significance: The proposed strategy provides a simple method for the production of high efficiency antigen-targeted imaging probes for tumor diagnosis.