Controlled trapping and release of quantum dots in a DNA-switchable hydrogel

The nanoscopic aspects of a switchable polyacrylamide (PAAm) hydrogel using fluorescent semiconductor quantum dots (QD) as probe particles was investigated. The diffusion properties of the QD's in the gel are studied using single-molecule fluorescence microscopy and fluorescence correlation spectroscopy. The diffusion behavior of the tracer particles was studied in the sol and the gel states of the switchable gel to characterize the trapping and release process. The QD's were made water soluble by a polymer coating that slightly increased their radius. The exponent β was included in the fit function used for the analysis of the FCS data to obtain an estimate of the extent of anomalous behavior. It was observed that the DNA-crosslinked hydrogels are capable of trapping and releasing nanoparticles on demand.