Multi-sensory fiber-optic probes using nanocrystals as the sensing materials are shown to overcome most limitations
imposed by those using organic dyes as the fluence-rate sensing materials. These nanocrystals are shown to be excitable
by a wide range of wavelengths covering the entire tissue transparent window utilized by various light-enabled
treatment modalities. The optical response of the sensors made from the nanocrystals is shown to be linear without any
sign of photobleaching and sensor crosstalk over a wide range of irradiance and fluence. Fiber probes using the
nanocrystals are promising in offering high spatial resolution in fluence-rate dosimetry for photodynamic therapy and
A technique to produce fluorescent cell phantom standards based on calcium alginate microspheres with encapsulated fluorescein-labeled dextrans is presented. An electrostatic ionotropic gelation method is used to create the microspheres which are then exposed to an encapsulation method using poly-l-lysine to trap the dextrans inside. Both procedures were examined in detail to find the optimal parameters producing cell phantoms meeting our requirements. Size distributions favoring 10-20 microns microspheres were obtained by varying the high voltage and needle size parameters. Typical size distributions of the samples were centered at 150 μm diameter. Neither the molecular weight nor the charge of the dextrans had a significant effect on their retention in the microspheres, though anionic dextrans were chosen to help in future capillary electrophoresis work. Increasing the exposure time of the microspheres to the poly-l-lysine solution decreased the leakage rates of fluorescein-labeled dextrans.