LbL-assembled multilayer films of dendritic star polymers: surface morphology and DNA hybridization detection

Positively or negatively charged water soluble core-shell star polymers consisting of a dendritic polyphenylene core and an outer flexible shell have been employed for the assembly of multilayer films. The multilayer films were fabricated via the layer-by-layer assembly (LbL) of the oppositely charged dendritic star polyelectrolytes and characterized by surface plasmon resonance spectroscopy (SPR). The assembled multilayer films exhibit morphology changes by undergoing considerable structural reorganization upon post-treatment under different pH conditions. Kinetic binding of probe DNA molecules on the outmost negatively charged surface was studied by SPR as well and showed stable DNA immobilization. DNA hybridization was investigated by surface plasmon field enhanced fluorescence spectroscopy (SPFS), whose hybridization behaviors from one mismatch and complementary target DNA molecules were significantly distinguished. The SPFS based DNA detection on dendritic star polymer multilayers represents a new candidate for the development of DNA biosensors or DNA microarrays.