title: Highly sensitive and label-free electrochemical detection of microRNAs based on triple signal amplification of multifunctional gold nanoparticles, enzymes and redox-cycling reaction.
abstract: MicroRNAs (miRNAs) are believed to be important for cancer diagnosis and prognosis, serving as reliable molecular biomarkers. In this work, we presented a label-free and highly sensitive electrochemical genosensor for miRNAs detection with the triple signal amplification of gold nanoparticles (AuNPs), alkaline phosphatase (ALP) and p-aminophenol (p-AP) redox cycling. The label-free strategy is based on the difference in the structures of RNA and DNA. Specifically, miRNAs were first captured by the pre-immobilized DNA probes on a gold electrode. Next, the cis-diol group of ribose sugar at the end of the miRNAs chain allowed 3-aminophenylboronic acid (APBA)/biotin-modified multifunctional AuNPs (denoted as APBA-biotin-AuNPs) to be attached through the formation of a boronate ester covalent bond, which facilitated the capture of streptavidin-conjugated alkaline phosphatase (SA-ALP) via the biotin-streptavidin interaction. After the addition of the 4-aminophenylphosphate (p-APP) substrate, the enzymatic conversion from p-APP to p-AP occurred. The resulting p-AP could be cycled by a chemical reducing reagent after its electro-oxidization on the electrode (known as p-AP redox cycling), thus enabling an increase in the anodic current. As a result, the current increased linearly with the miRNAs concentration over a range of 10 fM-5 pM, and a detection limit of 3 fM was achieved. We believe that this work will be valuable for the design of new types of label-free and sensitive electrochemical biosensors.
authors.affiliation: College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000, People's Republic of China. Electronic address: liulin@aynu.edu.cn.
authors.forename: Lin
authors.initials: L
authors.lastname: Liu
authors.forename: Ning
authors.initials: N
authors.lastname: Xia
authors.forename: Huiping
authors.initials: H
authors.lastname: Liu
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Kang
authors.forename: Xiaoshuan
authors.initials: X
authors.lastname: Liu
authors.forename: Chan
authors.initials: C
authors.lastname: Xue
authors.forename: Xiaoling
authors.initials: X
authors.lastname: He
mesh_terms: D000627:Aminophenols / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D004247:DNA / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D006801:Humans; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D035683:MicroRNAs / Q000737:chemistry / Q000302:isolation & purification*; D010084:Oxidation-Reduction
chemical_list: D000627:Aminophenols; D035683:MicroRNAs; D006046:Gold; D004247:DNA; C026729:4-aminophenol
keywords: Alkaline phosphatase; Electrochemical genosensors; Gold nanoparticles; MicroRNAs; Redox cycling; Triple signal amplification