Rapid pathogen detection and identification of its serovars are crucial to provide essential treatment during pandemic circumstances. Herein, we developed a facile and versatile FRET-based aptasensor for rapid Salmonella paratyphi A detection. The ssDNA aptamers specific towards pathogenic Salmonella paratyphi A were generated via whole-cell SELEX. The aptamer was conjugated onto quantum dot (QD) that served as the molecular beacon and graphene oxide (GO) was used as fluorescence quencher. The detection of Salmonella paratyphi A leads to the quenching of QD fluorescence due to the non-covalent interaction between GO and CdTe quantum dot. The assay shows a detection limit up to 10 cfu·mL−1 with no cross-reactivity towards closely related species. The spiking analysis demonstrated an inter-assay coefficient of variance less than 8 % and recovery rate between 85%-102% mitigates assay reliability. Further analysis with commercially available ELISA kit validated the reliability of the developed aptasensor. Furthermore, molecular dynamics simulation was used to establish the mechanism of action of generated aptamer against bacterial DNA gyrase protein. The strong non-bonded interaction energies along with hydrogen bonds between the aptamer and protein inhibit the function of the bacteria.

中文翻译：

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基于FRET的适体测定可灵敏检测副伤寒沙门氏菌A及其分子与DNA促旋酶的相互作用

快速的病原体检测和血清型鉴定对于在大流行期间提供必要的治疗至关重要。本文中，我们开发了一种基于FRET的灵活多功能通用型aptasensor，可快速检测副伤寒沙门氏菌A。通过全细胞SELEX产生对致病性副伤寒沙门氏菌A特异的ssDNA适体。适体共轭到用作分子信标的量子点（QD）上，而氧化石墨烯（GO）用作荧光猝灭剂。副伤寒沙门氏菌的检测由于GO和CdTe量子点之间的非共价相互作用，A导致QD荧光猝灭。该测定法显示了最高10 cfu·mL-1的检测极限，并且与紧密相关的物种没有交叉反应。峰值分析表明，测定间变异系数小于8％，回收率在85％-102％之间可降低测定的可靠性。使用市售ELISA试剂盒进行的进一步分析验证了开发的适体传感器的可靠性。此外，使用分子动力学模拟建立了适体对细菌DNA促旋酶蛋白的作用机理。适体和蛋白质之间的强非键相互作用能以及氢键抑制了细菌的功能。