Contrast agents for optical imaging have traditionally been designed for the near-infrared (NIR) spectral range (700-900 nm, Optical Window I) where absorption and scattering of tissue are relatively low. Recently, another window beyond 1000 nm has been discovered known as Optical Window II or the extended Near Infrared (exNIR) with improved transparency. In this work, we present a method to synthesize quantum dots emitting at 1300 nanometers, the optimal wavelength. The quantum dots were synthesized in organic solvents, and a method of transforming them into water is discussed. Optical characterizations including absolute quantum yield and the fluorescence lifetime are presented.
Thermal ablation is a promising minimally invasive method for treating tumors without surgical intervention. Thermal
ablation uses thermal sources such as lasers, radiowaves or focused ultrasound to increase the temperature of the tumor
to levels lethal to cancer cells. This treatment based on heat therapy may be problematic as the temperature of the
operation site is unknown. To address this problem, we developed optical molecular thermometers that can potentially
measure the temperature on a molecular scale and be compatible with in vivo measurements. The thermometers are
centered on a combination of two fluorophores emitting in two distinct spectral ranges and having different temperature-dependent
emission properties. In this design, a fluorophore with relatively insensitive temperature-dependent
fluorescence serves as a reference while another sensitive fluorophore serves as a sensor. We have demonstrated the
feasibility of this approach using a coumarin-rhodamine conjugate. The sensitivity of the construct to the clinically
relevant ablation temperatures (20-85 °C) was demonstrated in vitro.