“…In recent years, fluorescent measurements have been extensively applied to environmental and biological analysis owing to its advantages, such as low-cost, operational simplicity, high sensitivity and real-time detection (Chen et al, , 2013Li et al 2014b). Due to these promising aspects, fluorescent immunosensors, as a kind of effective analytical technique, have been applied extensively in the quantitative detection of PSA (Oh et al, 2009). The "turn-off" switch system is commonly used for variety of fluorescence immunosensors.…”