Electrochemical detection of oligonucleotide by attaching redox probes onto its backbone

An integrated electrochemical POCT platform for ultrasensitive circRNA detection towards hepatocellular carcinoma diagnosis

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related death. Circ-CDYL, one of the circular RNAs (circRNAs), is recognized as an independent marker for HCC early diagnosis. Point-of-care testing (POCT) of circRNA is essential and in great demand for clinical applications. Herein, we report a fully integrated electrochemical POCT platform for circRNA detection based on Au nanoflowers (AuNFs)/peptide nucleic acid (PNA) modified carbon-fiber microelectrode (CFME). PNA is applied as the recognition element, highly specified for a back-splice junction of circRNA. AuNFs increased active site for PNA probes, improving target-capturing efficiency at an ultralow level. The platform provides a linear range of 10 fM to 1 μM, with a detection limit as low as 3.29 fM. This biosensor demonstrates high specificity towards one-base mismatch and is stable for up to 24 days. The analytical performance has also been verified in human serum samples, demonstrating the potential utility in clinical POCT applications for HCC.

Application of peptide nucleic acid in electrochemical nucleic acid biosensors

The early diagnosis of major diseases, such as malignant tumors, has always been an important field of research. Through screening, early detection of such diseases, and timely and effective treatment can significantly improve the survival rate of patients and reduce medical costs. Therefore, the development of a simple detection method with high sensitivity and strong specificity, and that is low cost is of great significance for the diagnosis and prognosis of the disease. Electrochemical DNA biosensing analysis is a technology based on Watson Crick base complementary pairing, which uses the capture probe of a known sequence to specifically recognize the target DNA and detect its concentration. Because of its advantages of low cost, simple operation, portability, and easy miniaturization, it has been widely researched and has become a cutting-edge topic in the field of biochemical analysis and precision medicine. However, the existing methods for electrochemical DNA biosensing analysis have some shortcomings, such as poor stability and specificity of capture probes, insufficient detection sensitivity, and long detection cycles. In this review, we focus on improving the sensitivity and practicability of electrochemical DNA biosensing analysis methods and summarize a series of research work carried out by using electrically neutral peptide nucleic acid as an immobilized capture probe.

Nitronyl nitroxide monoradical TEMPO as new electrochemical label for ultrasensitive detection of nucleic acids

In this work, a novel electrochemical biosensor based on nitronyl nitroxide monoradical 2,2,6,6-tetramethylpiperidine 1-Oxyl (TEMPO) as new electrochemical label for facile nucleic acids detection is developed. This fast and convenient functional microelectrode was designed by fixing the capture probe peptide nucleic acid (PNA) and using the coordination interaction of Zr⁴⁺ with both phosphate groups and carboxyl groups. Differential pulse voltammetry (DPV) was used to study the oxidation current of TEMPO which was combined with the electrode surface and labeled. TEMPO electrochemical signal related to target deoxyribonucleic acid (tDNA) concentration was finally detected when tDNA was added on the surface of glassy carbon electrode (GCE). The detection principle, optimization of key factors and performance analysis of the biosensor are also discussed. A great linear relation is acquired within the scope of 10 pM-100 nM under optimal conditions and the detection limit of this experiment is calculated as low as 2.57 pM (R² = 0.996). In addition, complex serum samples were used to explore the practical application of this experiment. The results show the developed electrochemical DNA biosensor has wide application prospects in nucleic acids detection and clinical analysis.

Highly sensitive determination of DNA via a new type of electrochemical zirconium signaling probe

Exploiting Zr(iv) as a redox probe for the detection of DNA has great potential in clinical analysis.

PEI/Zr⁴⁺-coated nanopore for selective and sensitive detection of ATP in combination with single-walled carbon nanotubes

By virtue of a biomimetic nanopore and single-walled carbon nanotubes, a new sensor for adenosine triphosphate (ATP) detection is designed. As compared to the routine approach, the present scenario does not entail the surface modification of nanopore with analyte-specific probes. The underlying mechanism relies on a symmetric nanopore sequentially modified with polyethyleneimine (PEI) and Zr(4+) that can quantitate the concentration of ATP-bound aptamer, while other free aptamers are removed by single-walled carbon nanotubes (SWNTs). The detection limit of the nanopore sensor is 27.46 nM, and the linear range is from 50 nM to 400 nM. The biosensor with an excellent selectivity against guanosine triphosphate (GTP), uridine triphosphate (UTP), and cytosine triphosphate (CTP) can be applied in the real samples such as Hela cell.

Biomimetic nanopore for sensitive and selective detection of Hg(ii) in conjunction with single-walled carbon nanotubes

Through SWNTs, duplex DNA derived from folding of single-stranded DNA can be quantitated with Zr⁴⁺–PEI coated cone-shaped nanopore. With Hg²⁺ detection, sensitivity and selectivity based on this paradigm is guaranteed without probe immobilization.

Characterization of phenomena occurring at the interface of chiral conducting surfaces

Chiral conducting surfaces based on leucine functionalized terthiophenes can detect bioorganic molecules via formation of hydrogen bonds.

Detection of CREB phosphorylation via Zr (IV) ion mediated signal amplification

Phosphorylation of protein plays a vital regulatory role in a variety of biological processes. We herein report a novel method to assay the level of phosphorylated cAMP-response element binding protein (CREB) via Zr(4+) mediated signal amplification using gold nanoparticle/DNA/methylene blue (GNP/DNA/MB) nanocomposites. In this method the probe DNA immobilized at a gold electrode surface can specifically and efficiently recognize the phosphorylated target protein CREB. Then Zr(4+) links the phosphorylated CREB with GNP/DNA/MB nanocomposites by coordinating the phosphate groups on both CREB and the nanocomposites. Since the nanocomposites can provide high sensitivity (limit of detection: 0.25 nM) for the detection, efficient and highly sensitive bioanalysis of the expression level of phosphorylated protein CREB in human placenta tissues has also been conducted in this work. Our method is reported which shows acceptable stability, reproducibility for assaying of the protein phosphorylation states in real biosamples under physiological and pathological conditions with great potential for clinical applications in future.