Rational design of an allosteric G-quadruplex aptamer probe for ultra-sensitive detection of melamine in milk

• Published in: International journal of biological macromolecules 2022-06, Vol.210, p.430-438
• Main Authors: Xie, Zhuohao, Li, Peng, Zhan, Haonan, Zhuang, Liuyan, Tao, Sijian, Deng, Liehua, Huang, Jiahao
• Format: Article
• Language: English
• Subjects: Conformational change; G-quadruplex aptamer; Thymine-melamine-thymine
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2022.04.198

Efficient and accurate detection of melamine in dairy products remains a crucial yet challenging task. Herein, an allosterically modulated G-quadruplex-integrated aptamer is rationally designed with thymine-rich recognition termini for melamine binding. The detection process is facile by simply introducing the analyte into the mixture consisting of G-quadruplex aptamer probes, exonuclease III, and thioflavin T (ThT). The detection feasibility is confirmed by the polyacrylamide gel electrophoresis and fluorescence measurement results. This exonuclease III-assisted signal amplifiable approach works well in a linear range from 0.1 nM to 0.1 μM. Moreover, a detection limit as low as 83 pM is easily achieved, which is almost five orders of magnitude smaller than the maximum allowable melamine levels (about 8 μM) defined by many countries all over the world. The whole assay time for each test is no longer than 1 h. Additionally, the scheme is highly specific and satisfactory recovery rates (from 91% to 104%) are readily obtained when challenged with melamine-spiked milk samples. Therefore, the label-free, turn-on, low-cost, and time-efficient method can be used for reliable detection of melamine in an easily manipulated and ultra-sensitive manner, which may find its utilization in the field of food safety, biomedical engineering, and clinical diagnosis. •A label-free, turn-on, and one-step assay method is constructed for reliable detection of melamine by using an allosterically modulated G-quadruplex aptamer probe.•An excellent detection limit of 83 pM is readily achieved with a linear range from 0.1 nM to 0.1 μM.•The method exhibited good selectivity and anti-interference ability, as well as satisfactory recovery rates in milk samples with low relative standard deviations.•The scheme is easily manipulated and relatively inexpensive, and holds a promising potential in the field of food safety.