Quantum dot-containing polymer particles with thermosensitive fluorescence

Composite polymer particles consisting of a solid poly(acrolein-co-styrene) core and a poly(N-vinylcaprolactam) (PVCL) polymer shell doped with CdSe/ZnS semiconductor quantum dots (QDs) were fabricated. The temperature response of the composite particles was observed as a decrease in their hydrodynamic diameter upon heating above the lower critical solution temperature of the thermosensitive PVCL polymer. Embedding QDs in the PVCL shell yields particles whose fluorescence is sensitive to temperature changes. This sensitivity was determined by the dependence of the QD fluorescence intensity on the distances between them in the PVCL shell, which reversibly change as a result of the temperature-driven conformational changes in the polymer. The QD-containing thermosensitive particles were assembled with protein molecules in such a way that they retained their thermosensitive properties, including the completely reversible temperature dependence of their fluorescence response. The composite particles developed can be used as local temperature sensors, as carriers for biomolecules, as well as in biosensing and various bioassays employing optical detection schemes.

► Particles containing a thermosensitive polymer and fluorescent QDs have been developed.
► Heating above certain critical temperature provokes reversible stretching of the polymer.
► Stretching of the polymer varies the distance between QDs.
► Change of the distance between QDs induces particle fluorescence response on temperature.
► Bioanalytical thermosensing in course of exothermic chemical reactions is demonstrated.