Temperature-induced emission enhancement of star conjugated copolymers with poly(2-(dimethylamino)ethyl methacrylate) coronas for detection of bacteria.

A facile strategy for temperature-induced emission enhancement of star conjugated copolymers has been developed for biodetection. The star copolymers (HCP-star-PDMAEMAs) with different poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) chain lengths were synthesized from the hyperbranched conjugated polymer (HCP) macroinitiator by atom transfer radical polymerization (ATRP). The star conjugated copolymers exhibited interesting thermoresponsive phase transitions with adjustable lower critical solution temperature (LCST) depending on the pH of copolymer solution. Above the LCST, the emission of HCP-star-PDMAEMAs was enhanced greatly through restriction of intermolecular aggregation of conjugated polymer cores by the collapse of PDMAEMA arms. By changing the PDMAEMA length, the emission performance of HCP-star-PDMAEMAs could be readily adjusted. Correspondingly, this temperature-dependent emission enhancement of HCP-star-PDMAEMAs was successfully applied in the highly sensitive detection of bacteria. Due to the existence of a hyperbranched conjugated core and many thermo-responsive PDMAEMA arms, the detection limit of E. coli could reach 10(2) cfu mL(-1).