Ultrasensitive Biosensors Detecting mA in Blood: Achieving Early Screening and Typing of Tumors.

N-methyladenosine (mA) modification is one of the most widespread RNA modifications in eukaryotes and is involved in cancer development and progression by regulating oncogene expression. Herein, a reticulated rolling circle amplification (RCA) cascade reaction was used to construct a novel electrochemical biosensor for ultrasensitive detection of mA, employing ferrocene-tyramine (Fc-Tyr) molecules as electroactive probes. In this strategy, the RCA cascade reaction not only amplifies specific circular DNA in the designed template to reduce the binding with similar nucleic acid sequences but also generates a long ssDNA through multiple repetitions to capture a large number of electrochemical signal probes and achieve the amplification of electrochemical biosensing signals.

An ultrasensitive electrochemical biosensor with dual-amplification mode and enzyme-deposited silver for detection of miR-205-5p.

An electrochemical biosensor based on dual-amplified nucleic acid mode and biocatalytic silver deposition was constructed using catalytic hairpin assembly-hybrid chain reaction (CHA-HCR). The electrochemical detection of silver on the electrode by linear sweep voltammetry (LSV) can be utilized to quantitatively measure miR-205-5p since the amount of silver deposited on the electrode is proportional to the target nucleic acid. The current response values exhibit strong linearity with the logarithm of miR-205-5p concentrations ranging from 0.

Detection of methyltransferase activity and inhibitor screening based on rGO-mediated silver enhancement signal amplification strategy.

DNA methylation refers to the chemical modification process of obtaining a methyl group by the covalent bonding of a specific base in DNA sequence with S-adenosyl methionine (SAM) as a methyl donor under the catalysis of methyltransferase (MTase), which is related to the occurrence of multiple diseases. Therefore, the detection of MTase activity is of great significance for disease diagnosis and drug screening. Because reduced graphene oxide (rGO) has a unique planar structure and remarkable catalytic performance, it is not clear whether rGO can rapidly catalyze silver deposition as an effective way of signal amplification.

An electrochemical immunosensor for the detection of Glypican-3 based on enzymatic ferrocene-tyramine deposition reaction.

An ultrasensitive electrochemical immunosensor based on signal amplification of the deposition of the electroactive ferrocene-tyramine (Fc-Tyr) molecule, catalyzed by horseradish peroxidase (HRP), was constructed for the detection of the liver cancer marker Glypican-3 (GPC3). Functional electroactive molecule Fc-Tyr is reported to exhibit both the enzymatic cascade catalytic activity of tyramine signal amplification (TSA) and the excellent redox properties of ferrocene. In terms of design, the low matrix effects inherent in using the magnetic bead platforms, a quasi-homogeneous system, allowed capturing the target protein GPC3 without sample pretreatment, and loading HRP to trigger the TSA, which induced a large amount of Fc-Tyr deposited on the electrode surface layer by layer as a signal probe for the detection of GPC3.