Preparation and characterization of human malignant melanoma ganglioside ScFv antibody conjugated quantum dot probe

Melanoma is a highly aggressive and deadly skin cancer. Few treatment options are available for patients with metastatic melanoma, and the global incidence of melanoma is increasing faster than that of other cancers. Therefore, it is vitally important to uncover and use genetic and epigenetic regulatory mechanisms at work during the development and progression of melanoma for better prevention, diagnosis and clinical management. The single-chain antibody (ScFv) has good stability, high antigen affinity, low molecular weight, blood and normal tissue clearance rate, faster and easier penetration into the tumor tissue, which made ScFv to have extremely wide range of application in tumor diagnosis, treatment and prevention. In this study, the prokaryotic expression vector with the anti-human melanoma gaglioside single chain variable fragment antibody gene (GD/ScFvMEL) was constructed, expressed in Escherichia coli and purified by cation-exchange chromatography. Purified GD/ScFvMEL was combined with quantum dots (QD), which was evaluated by fluorescence spectrophotometer and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) electrophoresis. Finally, GD/ScFvMEL coated with QD (QD-GD/ScFvMEL) was transformed into malignant melanoma A375 cell line and human gastric cancer MGC-803 cell line to analyze its function by fluorescence microscopy. It was demonstrated that QD-GD/ScFvMEL could specifically bind with melanoma A375 cells and could not bind with stomach cancer MGC-803 cells, which showed that QD-GD/ScFvMEL could be used as a probe to diagnose melanoma. These results suggested that QD-GD/ScFvMEL has been successfully generated and may serve as a probe to detect malignant melanoma.