A new flow-through electrochemical aptasensor was designed for ultrasensitive monitoring of adenosine triphosphate (ATP) by coupling microvalve-programmable capillary column with CdS-functionalized DNA concatamer for signal amplification . Initially, a layer of primary DNA-conjugated polyacrylamide hydrogel was covalently linked onto the internal surface of capillary column, and then an automated sequenctial injection format with a syringe pump was employed for development of the programmable capillary-based aptasensor. In the presence of target DNA aptamer, the immobilized primary DNA hybridized with partial bases of the aptamer. The excess aptamer fregment could trigger the formation of DNA concatamer between auxiliary DNA 1 and CdS-labeled auxiliary DNA 2 . Upon target ATP introduction, a specific ATP-aptamer reaction was excuated, thereby resulting in the release of CdS-functionalized DNA concatamer from the capillary. Subsenquent anodic stripping voltammetric detection of cadmium released under acidic conditions from the released CdS nanoparticles could be conducted in a homemade detection cell. Under optimal conditions, the dynamic concentration range spanned from 0.1 pM to 10 nM ATP with a detection limit of 0.06 pM ATP. The electrochemical aptasensor showed good reproducibility, selectivity, and stability. In addition, the methodology was evaluated for the analysis of ATP spiked serum samples, and the recoveries was 81–140%.
Yue Zheng,Xiaoyu Wang,Shengquan He,Zehua Gao,Ya Di,Kunling Lu,Kun Li,Jidong Wang
A electrochemical biosensing strategy was developed for green and ultrasensitive detection of tumor cells by combining aptamer-DNA concatamer-CdTe quantum dots (QDs) signal amplification probe with mercury-free anodic stripping voltammetry (ASV). First, aptamer-DNA concatamer- CdTe QDs probes were designed by DNA hybridization and covalent assembling, which contained specific recognition of aptamer and signal amplification incorporating the DNA concatamer with QDs. Meanwhile, the capture electrode, glassy carbon electrode (GCE)/Graphene oxide (GO)/Polyaniline (PANI) / Glutaraldehyde (GA) / concanavalin A (Con A) was fabricated by a layer-by-layer assembling technique. K562 cells , as model cancer cells were detected to demonstrate the feasibility of this sensing strategy. Then, novel composite, graphene (GR)- Poly diallyldimethylammonium chloride (PDDA)/ L -Cysteine (L- Cys), was explored in ASV which replaced mercury electrodes using for determination of tumor cells. The proposed electrochemical biosensor showed high sensitivity with the detection limit of 60 cells mL −1 . More importantly, this novel design of signal amplification probes and the exploration of new composites in mercury-free ASV analysis would provide a promising method for ultrasensitive biosensor preparation and green electrochemical detection of tumor cells.
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