RESUMO
In this study, tri-functional immunofluorescent probes (Ce6-IgG-QDs) based on covalent combinations of quantum dots (QDs), immunoglobulin G (IgG) and chlorin e6 (Ce6) were developed and their photodynamic ability to induce the death of cancer cells was demonstrated. Strategically, one type of second-generation photosensitizer, Ce6, was first coupled with anti-IgG antibody using the EDC/NHS cross-linking method to construct the photosensitive immunoconjugate Ce6-IgG. Then, a complex of Ce6-IgG-QDs immunofluorescent probes was obtained in succession by covalently coupling Ce6-IgG to water soluble CdTe QDs. The as-manufactured Ce6-IgG-QDs maintained the bio-activities of both the antigen-antibody-based tumour targeting effects of IgG and the photodynamic-related anticancer activities of Ce6. By way of polyclonal antibody interaction with rabbit anti-human epidermal growth factor receptor (anti-EGFR antibody, N-terminus), Ce6-IgG-QDs were labelled indirectly onto the surface of human hepatocarcinoma (HepG2) cells in cell recognition and killing experiments. The results indicated that the Ce6-IgG-QDs probes have excellent tumour cell selectivity and higher photosensitivity in photodynamic therapy (PDT) compared with Ce6 alone, due to their antibody-based specific recognition and location of HepG2 cells and the photodynamic effects of Ce6 killed cells based on efficient fluorescence resonance energy transfer between QDs and Ce6. Copyright © 2015 John Wiley & Sons, Ltd.