Ratiometric nanothermometry via porphyrin inner filter effect applied to colloidal ZnS quantum dots

Abstract

Thermal sensing at the nanoscale is an attracted research field with potential applications in disparate areas from micro/nanoelectronics to nanomedicine. One of the driving forces of the research in the area is the design and fabrication of ratiometric thermometers combining materials with distinct thermometric properties. In this work, we provide an example of the combination of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (TPFPP) and colloidal ZnS/AOT quantum dots (QDs) as luminescent ratiometric thermal sensors acting within the physiological temperature range. Taking advantage of the overlap of the absorption band of the porphyrin with the emission band of the prepared colloidal ZnS/AOT QDs, the non-covalent nanoassemblies prepared presented ratiometric temperature sensing based on the so-called inner filter effect (or radiative energy transfer). In fact, the emission band of ZnS/AOT QDs at 411 nm is more pronounced by the absorbance of TPFPP. As an optical temperature sensor the TPFPP-ZnS/AOT QDs nanoassemblies showed good temperature reversibility, with a maximum relative thermal sensitivity of 0.95% ºC−1 at 50 ºC.