Spectral multiplexing using quantum dot tagged microspheres with diffusing colloidal probe microscopy

摘要

This work involves the development of a new technique that integrates DiffusingColloidal Probe Microscopy (DCPM) and luminescence to simultaneously measuremultiple particle-wall interactions. DCPM can be used to map potential energy profiles ofmultiple particle-surface interactions simultaneously and accurately. Colloidalsemiconductor quantum dots were used for spectral multiplexing to enable monitoring ofmultiple analytes at the same time.DCPM combines Total Internal Reflection Microscopy (TIRM) and VideoMicroscopy to simultaneously measure multiple particle-surface interactions withnanometer resolution in particle-surface separation. By acquiring the scattered intensityemitted by the particles, the separation distance can be calculated and subsequently theforces of interactions between the particle and the surface.This work demonstrates the use of luminescence instead of scattering as the modeof detection in DCPM. The luminescence is provided by quantum dots which areincorporated into polystyrene microspheres. The unique optical properties of quantumdots enable the creation of an optically multiplexed system where microspheres aretagged by quantum dots of different emission wavelengths. Scattering in DCPM may result in erroneous calculation of the potential energyprofiles because of particle polydispersity. Since scattering is dependent on particle size,luminescence is introduced into the system and some interesting results are obtained.These results illustrate that the effect of particle polydispersity is significantly reducedwhen luminescence is used as the mode of detection. This combined with the DCPMsystem?s sensitivity would enable the monitoring of multiple functionalized particlesurfaceinteractions simultaneously and accurately.