Lingwen Zeng

By Lingwen Zeng, Luxin Yu and Yinghui Zhang

Isothermal nucleic acid amplification is a simple process that rapidly and efficiently accumulates nucleic acid sequences at constant temperature such as 37 and 42°C. Isothermal nucleic acid amplification approach offers several advantages over temperature circle methods (such as PCR) including rapid assay results, cost-effectiveness, and portability. Two detection approaches based on circular strand-displacement polymerization reaction (CSDPR) were presented in this chapter for sensitive and specific thalassemia gene detection. One is a lateral flow strip biosensor based on CSDPR for semi-quantitative detection of thalassemia DNA. The other is a spectrophotometric DNA detection approach based on CSDPR for quantitative detection of thalassemia DNA.

Part of the book: Thalassemia and Other Hemolytic Anemias

By Lingwen Zeng, Zhiyuan Fang and Yunbo Wang

Two colorimetric assays, lateral flow biosensor (LFB) and hemin/G-Quadruplex DNAzyme-based colorimetric assay, were developed for the detection of copper ion based on click chemistry. Two single-strand DNA (ssDNA) with azide- and alkyne-modified at 3′ and 5′ separately can be linked by the Cu+-catalyzed click chemistry. For hemin/G-Quadruplex DNAzyme-based assay, the two ssDNA fragments linked by Cu+-catalyzed click chemistry could form a complete G-rich sequence that severed as a horse-radish peroxidase. In the presence of hemin and K+, the colorless substrate tetramethyl benzidine (TMB) is catalyzed into a colored product by the G-rich sequence. The concentration of Cu2+ can then be quantitatively analyzed by measuring the color density. For the LFB assay, the two ligated ssDNA fragments could form a sandwich complex between an ssDNA fragment immobilized on gold nanoparticles and another ssDNA fragment on test zone of a biosensor, respectively. The biosensor enables visual detection of copper ion with excellent specificity. In comparison with conventional methods, the present assays are simpler to operate and more cost-effective to use, and so have great potential in point-of-care diagnosis and environmental monitoring.

Part of the book: Noble and Precious Metals

By Lingwen Zeng, Shilin Cao, Hang Yin, Jun Xiong and Donghai Lin

In this chapter, the latest developments in graphene oxide-based biosensors are presented. These biosensors are complexes of graphene oxide and biomacromolecules, including enzymes such as glucose oxidase, horseradish peroxidase, laccase, and nucleic acids such as DNA and RNA. The structure, design and preparation process (immobilization process) of the above graphene oxide-biomacromolecule composites were summarized. Some typical examples of immobilization of biological macromolecules are described. The immobilization efficiency and electrochemical performance of immobilized biomolecules based on graphene oxide were discussed, which may guide designing better graphene oxide-based biosensors.

Part of the book: Graphene Oxide

By Lingwen Zeng, Omar Mukama, Xuewen Lu, Shilin Cao and Donghai Lin

The identification of various targets such as bacteria, viruses, and other cells remains a prerequisite for point-of-care diagnostics and biotechnological applications. Nucleic acids, as encoding information for all forms of life, are excellent biomarkers for detecting pathogens, hereditary diseases, and cancers. To date, many techniques have been developed to detect nucleic acids. However, most of them are based on polymerase chain reaction (PCR) technology. These methods are sensitive and robust, but they require expensive instruments and trained personnel. DNA strand displacement amplification is carried out under isothermal conditions and therefore does not need expensive instruments. It is simple, fast, sensitive, specific, and inexpensive. In this chapter, we introduce the principles, methods, and updated applications of DNA strand displacement technology in the detection of infectious diseases. We also discuss how robust, sensitive, and specific nucleic acid detection could be obtained when combined with the novel CRISPR/Cas system.

Part of the book: Modulating Gene Expression

By Lingwen Zeng, Lei Peng, Dazhi Wu and Baoguo Yang

Food safety poses an increasing threat to human health worldwide. The development of analytical methods and techniques to ensure food safety is therefore of great importance. Electrochemical sensors provide unique opportunity to realize sensitive, accurate, rapid, and portable detection for food safety. They have the potential to overcome the restrictions and limitations of traditional methods. In this chapter, we review the progress of electrochemical sensors for the detection of food contaminants including heavy metals, illegal additives, pesticide residues, veterinary drug residues, biological toxins, and foodborne pathogen. Future perspectives and challenges are also discussed.

Part of the book: Nutrition in Health and Disease

By Shi-Lin Cao, Jin-Heng Hao, Wei-Dong Ou-Yang, Zi-Shi Chen, Yong-Si Lv and Ling-Wen Zeng

Part of the book: Color Detection