Amphiphilic AB(2) Y-shaped poly(styrene)-poly(N-isopropylacryamide)(2) block copolymer (PS-(PNI-PAAm)(2)) is prepared through selective amidation and Michael additions reactions, using omega-amino PS and omega-amino PNIPAAm chains as arms and 5-maleimidoisophthalic acid (MIPA) as a core. The first step is end-capping PS chains with MIPA via the Michael addition reaction between the amino groups of omega-amino PS and the maleimide group of MIPA. Incorporation of two PNIPAAm chains to PS-MIPA chain ends via amidation reaction between the amino groups of to-amino PNIPAAm and the carboxylic acid groups of PS-MIPA result in amphiphilic AB(2) Y-shaped PS-(PNIPAAm)2 block copolymer. The amphiphilic PS-(PNIPAAm)(2) block copolymer forms nanoparticles in aqueous solution, which exhibit a temperature-responsive characteristic due to the presence of PNIPAAm chains. The applications of the polymeric nanoparticles as fluorophore carriers and fluorescent sensors are also studied. (C) 2010 Elsevier Ltd. All rights reserved.