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 (similar to 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 (similar to 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. (c) 2007 Elsevier B.V. All rights reserved.