A single-bead telomere sensor based on fluorescence resonance energy transfer

• Published in: Analyst (London) Vol. 141; no. 10; pp. 3033 - 3040
• Main Authors: Fan, Xiao, Yue, Qiaoli, Li, Yanyan, Liu, Yingya, Qu, Lu-Lu, Cao, Yingnan, Li, Haitao
• Format: Journal Article
• Language: English
• Published: England 10.05.2016
• Subjects: Beads; Deoxyribonucleic acid; Detection; Energy transfer; Flow rate; Fluorescence; Microfluidics; Sensors
• ISSN: 0003-2654; 1364-5528
• DOI: 10.1039/c5an02543e

We present a 200 nm in-diameter single-bead sensor for the detection of single, unlabeled DNA molecules in solution using fluorescence resonance energy transfer technology. DNA-bound Alexa 488 and Crimson 625 loaded on commercial beads served as the donor and acceptor, respectively. Binding of the target DNA to the single bead sensor induces G-quadruplex stretching, resulting in a decrease in fluorescence energy transfer. G-rich telomere sequences formed a G-quadruplex structure in the presence of ZnTCPP, as demonstrated by the detection of two strong donor and acceptor signals. The sensitivity of the sensor was 1 fM. Under optimized conditions using a polydimethylsiloxane microfluidic device, we measured the number of sensor beads by direct counting. By controlling the flow rate via the probe volume, one sensing experiment can be completed in 5 minutes. Based on these results, we propose a new parameter-dependability (RS)-as a quantitative measure to judge the quality of a bio-sensor. This parameter is based on the ratio of the sensor and sensing sample fluorescence signals. This parameter can range from 0.1 to 100, where a value of 10 represents an optimized bio-sensor.