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Liu J, Li T, Qin H, Li L, Yan M, Zhu C, Qu F, Abd El-Aty AM. Self-assembly and label-free fluorescent aptasensor based on deoxyribonucleic acid intercalated dyes for detecting lactoferrin in milk powder. Front Nutr 2022; 9:992188. [PMID: 36185658 PMCID: PMC9521185 DOI: 10.3389/fnut.2022.992188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 08/29/2022] [Indexed: 11/13/2022] Open
Abstract
Lactoferrin (Lf), an iron-binding glycoprotein, regulates the immune system. It has broad-spectrum antimicrobial activity and is critical for child physical growth and development. As a common additive in the dairy industry, it is crucial to quantify LF content. This study established a self-assembly and universal fluorescence aptasensor for detecting LF in milk powder based on structure-selective dyes of PicoGreen intercalated in the label-free aptamer. Herein, the aptamer functions as both a specific recognition element against targets and a fluorescent signal reporter integrated with structure-selective dyes. First, the aptamer folds into a three-dimensional spatial structure based on complementary base pairings and intermolecular weak non-covalent interactions. Then, the dye is intercalated into the minor groove structures of the aptamer and triggers its potential fluorescent property. When the target exists, the aptamer binds to it preferentially, and its space structure unfolds. This causes the freeing of the subsequent dye and decreases the corresponding fluorescence. Hence, the reflected fluorescence signals could directly determine the target concentrations. Under the optimum conditions, a good linear relationship (R2, 0.980) was obtained in the Lf range from 20 to 500 nM with a detection limit of 3 nM (2.4 mg/kg) and good specificity, as well as a reliable recovery of 95.8–105.1% in milk powder. In addition, the universality was also confirmed with a good performance by quickly changing the aptamers against other targets (chlorpyrifos, acetamiprid, bovine thyroglobulin, and human transferrin) or utilizing another fluorescence dye. Therefore, this self-assembly aptasensor provides a universal and concise strategy for effective detection.
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Affiliation(s)
- Jiahui Liu
- Institute of Quality Standard and Testing Technology for Agro-products, Shandong Academy of Agricultural Sciences, Jinan, China
- Shandong Provincial Key Laboratory Test Technology on Food Quality and Safety, Jinan, China
- College of Life Sciences and Food Engineering, Hebei University of Engineering, Handan, China
| | - Tengfei Li
- College of Life Sciences and Food Engineering, Hebei University of Engineering, Handan, China
| | - Hongwei Qin
- Institute of Quality Standard and Testing Technology for Agro-products, Shandong Academy of Agricultural Sciences, Jinan, China
- Shandong Provincial Key Laboratory Test Technology on Food Quality and Safety, Jinan, China
| | - Linsen Li
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Sciences, Beijing Institute of Technology, Beijing, China
| | - Mengmeng Yan
- Institute of Quality Standard and Testing Technology for Agro-products, Shandong Academy of Agricultural Sciences, Jinan, China
- Shandong Provincial Key Laboratory Test Technology on Food Quality and Safety, Jinan, China
- *Correspondence: Mengmeng Yan,
| | - Chao Zhu
- Institute of Quality Standard and Testing Technology for Agro-products, Shandong Academy of Agricultural Sciences, Jinan, China
- Shandong Provincial Key Laboratory Test Technology on Food Quality and Safety, Jinan, China
- Chao Zhu,
| | - Feng Qu
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Sciences, Beijing Institute of Technology, Beijing, China
| | - A. M. Abd El-Aty
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan, China
- Department of Pharmacology, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt
- Department of Medical Pharmacology, Medical Faculty, Ataturk University, Erzurum, Turkey
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Recent Progress and Opportunities for Nucleic Acid Aptamers. Life (Basel) 2021; 11:life11030193. [PMID: 33671039 PMCID: PMC7997341 DOI: 10.3390/life11030193] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 02/20/2021] [Accepted: 02/25/2021] [Indexed: 02/06/2023] Open
Abstract
Coined three decades ago, the term aptamer and directed evolution have now reached their maturity. The concept that nucleic acid could modulate the activity of target protein as ligand emerged from basic science studies of viruses. Aptamers are short nucleic acid sequences capable of specific, high-affinity molecular binding, which allow for therapeutic and diagnostic applications. Compared to traditional antibodies, aptamers have several advantages, including small size, flexible structure, good biocompatibility, and low immunogenicity. In vitro selection method is used to isolate aptamers that are specific for a desired target from a randomized oligonucleotide library. The first aptamer drug, Macugen, was approved by FDA in 2004, which was accompanied by many studies and clinical investigations on various targets and diseases. Despite much promise, most aptamers have failed to meet the requisite safety and efficacy standards in human clinical trials. Amid these setbacks, the emergence of novel technologies and recent advances in aptamer and systematic evolution of ligands by exponential enrichment (SELEX) design are fueling hope in this field. The unique properties of aptamer are gaining renewed interest in an era of COVID-19. The binding performance of an aptamer and reproducibility are still the key issues in tackling current hurdles in clinical translation. A thorough analysis of the aptamer binding under varying conditions and the conformational dynamics is warranted. Here, the challenges and opportunities of aptamers are reviewed with recent progress.
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Xu Y, Wu Q, Bai L, Mu G, Tuo Y, Jiang S, Zhu X, Qian F. Cloning, expression, and bioinformatics analysis and characterization of a β-galactosidase from Bacillus coagulans T242. J Dairy Sci 2021; 104:2735-2747. [PMID: 33455743 DOI: 10.3168/jds.2020-18942] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 10/13/2020] [Indexed: 12/13/2022]
Abstract
The activities of β-galactosidases from bacteria and molds are affected by temperature, pH, and other factors in the processing of dairy products, limiting their application, so it is necessary to find alternative lactases. In this study, the β-galactosidase gene from Bacillus coagulans T242 was cloned, co-expressed with a molecular chaperone in Escherichia coli BL21, and subjected to bioinformatic and kinetic analyses and lactase characterization. The results show that the enzyme is a novel thermostable neutral lactase with optimum hydrolytic activity at pH 6.8 and 50°C. The thermal stability and increased lactose hydrolysis activity of β-galactosidase in the presence of Ca2+ indicated its potential application in the dairy industry.
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Affiliation(s)
- Yunpeng Xu
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, China
| | - Qiong Wu
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, China
| | - Li Bai
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, China
| | - Guangqing Mu
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, China
| | - Yanfeng Tuo
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, China
| | - Shujuan Jiang
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, China
| | - Xuemei Zhu
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, China.
| | - Fang Qian
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, China.
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Karimi F, Dabbagh S. Gel green fluorescence ssDNA aptasensor based on carbon nanotubes for detection of anthrax protective antigen. Int J Biol Macromol 2019; 140:842-850. [PMID: 31470050 DOI: 10.1016/j.ijbiomac.2019.08.219] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 08/16/2019] [Accepted: 08/26/2019] [Indexed: 01/09/2023]
Abstract
Bacillus anthracis, the causative agent of anthrax, is a harmful pathogen with potential ability as a biological weapon which persuades scientists to develop novel methods to detect anthrax from infected resources. In this study, a multi-walled carbon nanotube (MWCNTs)-based fluorescence aptasensor was fabricated to detect the recombinant protective antigen domain 4 (rPAD4) of Bacillus anthracis as the most important key factor in development of anthrax. First, PAD4 was recombinant expressed in E. coli and purified by Ni-NTA column. Second, the affinity of aptamer to rPAD4 was confirmed by ELAA assay. In aptasensor design, the aptamer was labeled with Gel Green and immobilized on MWCNTs. Upon the adsorption of labeled aptamer on MWCNTs, fluorescence emission was quenched. In contrast, by adding rPAD4 to hybridization reaction and incubation for 10 min, the fluorescence emission was significantly recovered to 85% compared to the control. Detection limit for the sensitivity and specificity of the aptasensor was determined 20 ng/ml and 62.5 ng/ml purified and unpurified rPAD4 protein, respectively. Also, applicability of aptasensor was showed in mouse serum sample. Finally, results indicated that nanosensor has the potential to be developed as a high-sensitive, cost-effective and fast-acting system for measuring of PA in anthrax diagnostic tests.
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Affiliation(s)
- Farrokh Karimi
- Department of Biotechnology, Faculty of Science, University of Maragheh, P.O. Box 55181-83111, Maragheh, Iran.
| | - Somayyeh Dabbagh
- Department of Biotechnology, Faculty of Science, University of Maragheh, P.O. Box 55181-83111, Maragheh, Iran
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