Single-Particle Electrochemical Biosensor with DNA Walker Amplification for Ultrasensitive HIV-DNA Counting

Abstract

Single-particle electrochemical collision has gained great achievements in fundamental research, but it is challenging to use in practice on account of its low collision frequency and the interference of the complex matrix in actual samples. Here, magnetic separation and DNA walker amplification were integrated to build a robust and sensitive single-particle electrochemical biosensor. Magnetic nanobeads (MBs) can specifically capture and separate targets from complex samples, which not only ensures the anti-interference capability of this method but also avoids the aggregation of platinum nanoparticles (Pt NPs) caused by numerous coexisting substances. A low amount of targets can lead to the release of more Pt NPs and the generation of more collision current transients, realizing cyclic amplification. Compared with simple hybridization, a DNA walker can improve the collision frequency by about 3-fold, greatly enhancing detection sensitivity, and a relationship between collision frequency and target concentration is used to realize quantification. The biosensor realized an ultrasensitive detection of 4.86 fM human immunodeficiency virus DNA (HIV-DNA), which is 1–4 orders of magnitude lower than that of traditional methods. The successful HIV-DNA detection in complex systems (serum and urine) demonstrated a great promising application in real samples and in the development of new single-entity biosensors.

DNA Walkers for Biosensing Development

“…[106] The DNA walker strategy was proposed on the basis of protein bindinginduced proximity recognition and polymerase amplification. The hairpin-like DNA tracks were immobilized on the electrode, [96] Copyright 2021, American Chemical Society. b) DNA walkers for imaging miRNA.…”

“…a) DNA walkers for biosensing HIV-DNA. Reproduced with permission [96]. Copyright 2021, American Chemical Society.…”

Single DNA Origami Detection by Nanoimpact Electrochemistry

“…It has also been utilised as a biosensor to indirectly detect tumour biomarkers [10] and viral DNA. [11] However, so far, little work has been focused on the detection of DNA self-assembled nanostructures. The main reason is that DNA is not electrochemically active in terms of current density and reversibility.…”

“…This method has been used with inorganic and organic nanoparticles, [5] emulsion droplets, [6] lipid vesicles, [7] bacteria, [8] viruses and enzymes, [9] . It has also been utilised as a biosensor to indirectly detect tumour biomarkers [10] and viral DNA [11] . However, so far, little work has been focused on the detection of DNA self‐assembled nanostructures.…”

Intraparticle and Interparticle Transferable DNA Walker Supported by DNA Micelles for Rapid Detection of MicroRNA

“…5−7 Owing to the excellent molecular recognition ability, self-driven capacity, accelerated reaction rate, and superior signal amplification capability, the 3D DNA walker has been applied in biosensing, intracellular imaging, molecular computation, and clinical diagnostics. 8−13 According to the anchoring type of walking arms, the 3D DNA walker can be divided into two categories: fixed-arm walker 9,14 and free-arm walker. 8,15 Nevertheless, these two types of walkers usually have to anchor the DNA tracks on the 3D landscapes via covalent or coordinate bonds, which complicates their construction processes.…”