* Superscripts and subscripts cannot be displayed on Toutiao today. For a better reading experience, please go to the WeChat official account.
*Go to the " nanozyme Nanozymes" public account to learn the latest news about nanozymes!
*This article was first published on the "Nanozymes" public account on March 18, 2022
*Editor: Yu Jiyuan
As a natural enzyme substitute, nanozymes are simple to prepare, have high chemical and thermal stability, and have strong catalytic activity. Its advantages such as easy functionalization are favored by scientific researchers, and it has been widely used in research fields such as biosensing, bioimaging, drug delivery and treatment. As an emerging graphene-like two-dimensional sheet material, molybdenum disulfide has been proven to have excellent peroxidase simulation activity and can replace the biological enzyme for building biosensors.
In this study, gold-platinum core-shell bimetallic nanoparticles with excellent catalytic activity and enzyme-like activity were functionalized onto the surface of molybdenum disulfide through an in-situ growth method to prepare a molybdenum disulfide-based nanocomposite (MoS2-Au@ Pt). The nanocomposite not only has better biological enzyme-like activity, but also has different affinities for single-stranded and double-stranded DNA. Based on this, this study combined the target-triggered catalytic hairpin assembly (CHA) reaction to design a label-free, highly sensitive colorimetric sensor for the detection of avian influenza (H7N9) virus gene sequences. As shown in Figure 1, neck-loop structure probes HP1 and HP2 with sticky ends are co-adsorbed on the surface of MoS2-Au@Pt nanocomposite. At this time, the adsorbed HP1 and HP2 occupied the catalytic site of the MoS2-Au@Pt nanocomposite, reducing its enzyme-like catalytic activity and making the TMB solution lighter in color. With the addition of H7N9, H7N9 serves as the initiator strand and triggers the classic CHA reaction, generating HP1-HP2 double strands and releasing H7N9 for the next step of the CHA reaction. Due to the low affinity of the MoS2-Au@Pt nanocomposite to double-stranded DNA, the HP1-HP2 double strands detached from the nanomaterial interface, restoring the catalytic activity of the MoS2-Au@Pt nanocomposite, and the color of the TMB solution turned dark blue. Based on the color of the solution and the intensity of the absorption peak, H7N9 can be determined qualitatively and quantitatively.
Figure 1. Colorimetric sensor based on MoS2-Au@Pt nanocomposite for label-free detection of H7N9.
Under optimal experimental conditions, the analytical performance of the colorimetric sensor based on the nanocomposite material is shown in Figure 2. As the concentration of H7N9 increases, the color of the TMB solution gradually turns blue, and the intensity of its corresponding UV absorption peak also gradually increases. This is because H7N9 continuously triggers the CHA reaction, causing HP1 and HP2 to continuously detach from the surface of the MoS2-Au@Pt nanocomposite, prompting the continuous recovery of the catalytic activity of the nanocomposite. When the H7N9 concentration is 10 pM-50 nM, the intensity of the UV adsorption peak of the colorimetric sensor has a linear relationship with the logarithm of the H7N9 concentration , and the detection limit is estimated to be 2.8 pM (picomolar). The sensor not only has a wide detection range, but also has excellent detection selectivity and can significantly distinguish other viral nucleic acid gene sequences such as H1N1, ZIKA, and DENA. In addition, the sensor also has good repeatability, with the relative standard deviation (RSD) of 6 different detection results being only 1.74%. Based on the above-mentioned excellent detection performance, this colorimetric sensor can be used for the analysis and determination of H7N9 in actual systems, and the detection results are satisfactory. The above results show that the MoS2-Au@Pt nanocomposite with peroxidase activity is a promising nanomaterial that can be combined with nucleic acid aptamers to construct a universal colorimetric sensing platform for chemical or biological targets. Efficient detection of molecules.
Figure 2. Analytical performance of this colorimetric sensor.
(A) Detection of UV absorption peaks of H7N9 at different concentrations.
(B) Linear relationship between the corresponding peak intensity differences in panel A and H7N9 concentration.
(C) Selectivity of this colorimetric sensor.
(D) Repeatability of this colorimetric sensor.
The above research work was published on Langmuir and was completed by the research groups of Professor Su Shao and Professor Wang Lianhui of the School of Materials Science and Engineering, Nanjing University of Posts and Telecommunications. The first author is master student Dong Yan.
Recommended in previous issues
Anal. Chem. | AuPtCo ternary alloy nanozyme for chemiluminescent bioanalysis
ACS Sensors | Microfluidic colorimetric biosensor for rapid detection of Salmonella
Written by: Dong Yan
Reviewer: Feng Jiayuan
Editor: Yang Congzhong
