Dopamine–quantum dot conjugate: a new kind of photosensitizers for photodynamic therapy of cancers

The thiol-capped CdTe quantum dots (QDs) with the average size of 3.5 nm were linked to dopamines (DAs) forming DA–QD conjugates, with the characteristics of red-shifted photoluminescence (PL) peak and remarkably reduced PL lifetime. The QDs in the conjugates readily accept the electron from DAs when excited by the visible light, resulting in the oxidation of DAs and the production of singlet oxygen (1O2) with the yield comparable to that of sulfonated aluminum phthalocyanine (AlPcS), a popularly used photosensitizer. The DA–QD conjugate can quickly penetrate into human nasopharyngeal carcinoma (KB) cells and seriously destroy cells under the irradiation of visible lights, showing the potential to become a new kind of photosensitizers.