Modification of CdTe quantum dots as temperature-insensitive bioprobes

CdTe quantum dots (QDs) were synthesized in aqueous solution with 3-mercaptopropionic acid (MPA) as the stabilizer. The photoluminescence (PL) of CdTe QDs (3.5 nm) is found to be temperature-dependent: as the temperature arising from 278 K to 323 K, the PL intensity declines to 50.2% of its original and PL emission peak shows obvious red-shift (∼7 nm). After modification of the QDs surface with denatured ovalbumin, the PL is more temperature-insensitive than before. The PL intensity retains more than 70% of its original and the emission peak shows less red-shift (∼2 nm). Moreover, it is found that the PL intensity and wavelength of denatured ovalbumin coated CdTe QDs are reversible during heating (323 K)–cooling (278 K) cycles. All the studies provide an important theoretical basis for searching temperature-insensitive bioprobes.