Fabrication of a Deoxyribonuclease Sensor Based on the Electrical Characteristics of DNA Molecules

In this study, we developed a sensing device that can detect deoxyribonuclease (DNase) based on the electrical properties of deoxyribonucleic acid (DNA). We estimated the equivalent circuit between the electrodes with immobilized DNA and investigated whether the characteristics of the electrodes change before and after the DNase reaction. This method detects DNase by simply evaluating the electrical properties of DNA without using a fluorescent reagent. Therefore, inexpensive and highly accurate measurements can be performed with simple operations. However, detection sensitivity must be increased for practical feasibility. Hence, we investigated whether DNA immobilization is restricted by changing the shape of the electrode to a triangle with sharp edges, which may improve the sensitivity of DNase. Additionally, we attempted to detect DNase from an extremely small amount of sample solution using a microchannel. The device was able to quantitatively analyze DNase I activity with a detection limit of 5.5 × 10^-5 unit/μL. The results demonstrate the effectiveness of the proposed sensing device for various medical applications.

Nanoparticles as Emerging Labels in Electrochemical Immunosensors

This review shows recent trends in the use of nanoparticles as labels for electrochemical immunosensing applications. Some general considerations on the principles of both the direct detection based on redox properties and indirect detection through electrocatalytic properties, before focusing on the applications for mainly proteins detection, are given. Emerging use as blocking tags in nanochannels-based immunosensing systems is also covered in this review. Finally, aspects related to the analytical performance of the developed devices together with prospects for future improvements and applications are discussed.

A novel electrochemical DNA biosensor for transgenic soybean detection based on triple signal amplification

A novel electrochemical DNA biosensor was developed and MON89788 of soybean transgenic gene sequence was detected based on a strategy of rolling circle amplification (RCA) and gold nanoparticle cube (AuNPC)-labeled multiple probes. First, the mercapto-modified capture DNA was immobilized on the surface of the Fe3O4@Au magnetic nanoparticles via an Au-S bond, and the capture DNA was opened and complementarily hybridized with the target DNA to form a double-stranded DNA. In the 10 × reaction buffer, Exonuclease III (ExoIII) specifically recognized and sheared the double-stranded DNA to release the target DNA, which led to the next round of reaction. Afterward, AuNP cube-loaded ssDNA (AuNPC/DNA) was added with the rolling circle reaction with the help of Phi29 DNA polymerase and T4 ligase. Finally, [Ru(NH3)6]3+ was attracted directly by the anionic phosphate of ssDNA via electrostatic interaction. The determination was carried out by using chronocoulometry (CC), and the CC signal was recorded. The mass amount of DNA strands extended infinitely on the AuNPs cube and numerous [Ru(NH3)6]3+ were absorbed, thus the detected signal was highly amplified. The corresponding CC signal showed a good linear relationship with the logarithm of the target DNA concentration in the range of 1 × 10-16 to 1 × 10-7 mol L-1, with a detection limit of 4.5 × 10-17 mol L-1. Specific gene sequence of MON89788 in soybean samples was determined, and the recoveries ranged from 97.3% to 102.0%. This sensor is one of the most sensitive sensors for genetic sequence assessment at present. Moreover, it demonstrates good selectivity, stability, and reproducibility.

Progress in biosensor based on DNA-templated copper nanoparticles

During the last decades, by virtue of their unique physicochemical properties and potential application in microelectronics, biosensing and biomedicine, metal nanomaterials (MNs) have attracted great research interest and been highly developed. Deoxyribonucleic acid (DNA) is a particularly interesting ligand for templating bottom-up nanopreparation, by virtue of its excellent properties including nanosized geometry structure, programmable and artificial synthesis, DNA-metal ion interaction and powerful molecular recognition. DNA-templated copper nanoparticles (DNA-CuNPs) has been developed in recent years. Because of its advantages including simple and rapid preparation, high efficiency, MegaStokes shifting and low biological toxicity, DNA-CuNPs has been highly exploited for biochemical sensing from 2010, especially as a label-free detection manner, holding advantages in multiple analytical technologies including fluorescence, electrochemistry, surface plasmon resonance, inductively coupled plasma mass spectrometry and surface enhanced Raman spectroscopy. This review comprehensively tracks the preparation of DNA-CuNPs and its application in biosensing, and highlights the potential development and challenges regarding this field, aiming to promote the advance of this fertile research area.

Recent advances in the synthesis and application of copper nanomaterials based on various DNA scaffolds

Fluorescent copper nanomaterials (CuNMs), including copper nanoparticles (CuNPs) and copper nanoclusters (CuNCs), become more and more popular with the abundant raw materials and low cost. A wide range of applications has been explored due to their fascinating properties such as low toxicity, remarkable water solubility, facile synthesis, large Stokes shifts, and good biocompatibility. As a kind of genetic material, DNA exhibits its molecular recognition function and diversity. The marriage between CuNMs and DNA endows DNA-templated CuNMs (DNA-CuNMs) with unique properties such as fluorescence, electrochemiluminescence and catalytic features. In this review, we summarize the synthesis and recent applications of DNA-CuNMs. Fluorescent CuNMs can be grown on various DNA scaffolds with special sequence design. T base plays an important role in the formation of CuNMs on DNA templates. These fluorescent DNA-CuNMs hold great prospect in logic gate construction, staining and biosensing of DNAs and RNAs, ions, proteins and enzymes, small molecules and so on.