A folate receptor fluorescence sensor based on terminal protection and exonuclease I assisted cleavage-induced DNAzyme releasing strategy

- A novel and amplified fluorescence assay for folate receptor activity was developed.
- Terminal protection and exonuclease I assisted cleavage-induced DNAzyme amplification.
- A detection limit of 0.2 ng/mL for folate receptor could be achieved.

The folate receptor (FR) is known as an attractive tumor marker that is expressed in a variety of cancers at high frequency. Based on the specific interaction of FR toward folic acid(FA)-linked DNA, we proposed a simple, rapid and selective fluorescent method for detection of FR based on terminal protection and exonuclease I (Exo I) assisted cleavage-induced DNAzyme releasing strategy. In the present system, with the addition of FR, the digestion of Exo I cannot proceed past the FR-linked DNA, then the 8-17 DNAzyme substrate was successfully conserved and show its cyclic catalytic cleavage toward molecular beacon (MB) substrate, resulting in an evident fluorescence signal enhancement. Combining with DNAzyme as a singal amplification, this developed terminal protection and Exo I assisted cleavage platform have detection concentration of FR range from 0.2 to 40 ng/mL and achieve a detection limit of 0.2 ng/mL. Moreover, we further employed the proposed method to measure FRs in serum samples with satisfactory results. This developed terminal protection and Exo I assisted cleavage strategy combined with 8-17 DNAzyme opens a promising avenue for FR detection, and should be also conveniently used for the sensor of other proteins or nucleic acid and may have widespread applications in biological process researches, drug discovery, and clinic diagnostics.

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