NanoMIP beacons with a co-operative binding mechanism for the all-in-one detection of methamphetamine aptamer complexes

Methamphetamine is a highly addictive stimulant with significant public health implications, necessitating the development of rapid, sensitive, and reliable detection methods. Traditional analytical techniques, though accurate, often involve complex sample preparation, expensive equipment, and lengthy analysis times. This study presents the design, synthesis, and application of nanoMIP beacons with a unique co-operative binding mechanism for the detection of methamphetamine. NanoMIP beacons selective for methamphetamine/aptamer complexes were synthesized using a solid-phase synthesis method that involved the bio-conjugation of an aptamer on the stationary phase and the incubation of methamphetamine to form a methamphetamine-aptamer complex. The resultant nanoMIP beacons were eluted off the affinity column and characterised using transmission electron microscopy. The co-operative binding mechanism, which relies on the structure-switching capability of the aptamer upon analyte binding was demonstrated through comparison of the fluorescence quenching signal of a scrambled sequence and nanoNIP controls. The fluorescence quenching assay was established using a fixed optimal concentration of aptamer and varying amounts of methamphetamine. The nanoMIP beacons showed enhanced the sensitivity (LOD = 23 ± 3.5 nM) and excellent selectivity, with a 40-fold increase in quenching for methamphetamine compared to other illicit drugs. The nanoMIP beacons demonstrated acceptable sample recoveries in both urine diluent and 50% human serum. This work provides a new strategy for the development of hybrid nanoMIP/aptamer-based sensors and provides a robust analytical tool for combating methamphetamine abuse.