Integration of ampicillin grafted tetracarboxylic functionalized magnetic nanoparticles and real-time loop-mediated isothermal amplification for ultrasensitive detection of Listeria monocytogenes

Listeria monocytogenes ( L. monocytogenes ), as a prevalent foodborne pathogen, is a major threat to global public health due to its high mortality rate and strong survival ability under limited conditions. Herein, a novel ampicillin grafted tetracarboxylic functionalized magnetic nanoparticles (ATMN) was fabricated and combined with real-time loop-mediated isothermal amplification (LAMP) for ultrasensitive detection of L . monocytogenes . Within one tube, ATMN could specifically capture target L. monocytogenes by the selective recognition between ampicillin on ATMN and penicillin binding proteins on the surface of L. monocytogenes , and then effectively isolate its DNA mainly through hydrogen bonds between carboxy on ATMN and DNA after in situ lysis. Interestingly, continuous enrichment and separation within one tube could obtain template DNA. Subsequently, the DNA was analyzed by real-time LAMP for accurate detection, in which the specific hly gene of L . monocytogenes was selected as an indicator. To prove the practicability, ATMN linked real-time LAMP (ATMN-LAMP) strategy was proposed for rapid, specific, and ultrasensitive detection determination of L . monocytogenes in lettuce and raw pork. The ATMN-LAMP strategy exhibited ultrahigh sensitivity with limit of detection of 78 CFU mL −1 , and was successfully used for detecting L . monocytogenes in spiked real samples with recovery between 97.2% and 102.8% and relative standard deviation no more than 5.3%, respectively. Therefore, we believe that the ATMN-LAMP strategy exhibits the characteristics of low cost, high efficiency, and simple operation, and is expected to become a universal method for detecting various pathogens in complex biological samples.