Target-triggered tertiary amplifications for sensitive and label-free protein detection based on lighting-up RNA...

Proteins play vital roles in regulating a series of living activities and can be potentially considered to be useful indicators for diagnosing various diseases. Here, a target-triggered transcription cascade amplification strategy with the use of the fluorescence switch-on RNA aptamer is constructed for label-free and sensitive platelet-derived growth factor-BB (PDGF-BB) protein biomarker detection. The target molecule of PDGF-BB binds a rationally designed multifunctional hairpin probe to switch its structure and to expose a primer binding region. The primer sequence further binds such a region to initiate the target recycling and lighting-up RNA aptamer transcription cascade cycles to yield tremendous RNA aptamers. And, the fluorescence of the organic dye is substantially enhanced upon binding to these RNA aptamers for realizing highly sensitive and label-free PDGF-BB detection with the detection limit being lowered to 0.8 pM. Moreover, the developed strategy has superior selectivity and exhibits a promising potential to detect PDGF-BB spiked into serums with buffer dilution, which makes this method an attractive sensing system for detecting other biomarkers at trace levels.