A colorimetric method for the detection of folate receptor based on terminal protection-assisted cascade signal amplification

In this paper, we have proposed a colorimetric method for the sensitive detection of folate receptor (FR) based on terminal protection-assisted cascade signal amplification. In the presence of target protein, the binding of FR and folate that is covalently conjugated at 3 terminal of probe DNA can induce significant steric hindrance to prevent exonuclease I-catalyzed degradation of probe DNA. So, rolling circle amplification can be carried out by using probe DNA as the ligation template and amplification primer, and the resulting DNAzymes can induce amplified colorimetric signals by catalyze H2O2-mediated oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS(2-)). By tracing DNAzyme catalysis-induced absorbance changes, the method has proven to be able to sensitively detect FR in the linear range from 1 ng/mL to 100 ng/mL with a detection limit of 0.46 ng/mL. This method can also easily distinguish the control protein (bovine serum albumin or ovalbumin) from the target protein. Therefore, our method may have great potential in clinical determination of biomarker proteins in the future. (C) 2014 Elsevier B.V. All rights reserved.