A near-infrared fluorescence-based optical Thermosensor

Abstract

Fluorescence-based sensors have attracted a great deal of attention because they allow for the specific, rapid and sensitive detection of nonfluorescent analytes by simple emission enhancement or quenching without special instrumentation.[1] Various fluorescent sensors have been developed to more accurately detect and image various types of analytes, including biomolecules, organic molecules, pH and ions. However, fluorescent sensors capable of detecting changes in environmental conditions such as temperature have rarely been described, even though the development of a fluorescence-based thermosensor is desired in industrial testing and manufacturing and also in many biomedical diagnostic and treatment processes, such as measuring induced hyperthermia around tumors and inflammation.[2] Especially, fluorescence-based optical thermosensors are advantageous compared to contact temperature sensors in monitoring temperature within micro/nanometer range (e.g., biological cells or nano/micro devices), where it is physically difficult to connect, since there is no contact with the medium in the measurement process.[3] Recently, fluorescent thermosensors derived from temperature-responsive organic molecules and polymers, such as poly(N-isopropyl acrylamide), have been studied and provide easy solutions for temperature monitoring on the basis of fluorescence emission intensity.[4], [5] However, there are no reports of fluorescent thermosensors capable of providing selective fluorescence visualization at a broad temperature range in real-time. This application is limited because these sensors only display fluorescence ratiometry of emissions, show modest fluorescence changes at a narrow temperature range, and therefore provide insufficient resolution.[5]