MIP-on-a-tip (MOT) as an innovative sensor for selective electrochemical determination of letrozole in plasma

Therapeutic drug monitoring of letrozole (LET) is very important for getting the best results in breast cancer treatment. Still, it is hindered by the lack of a rapid, highly sensitive point-of-care tool. This study presents the inaugural fully integrated molecularly imprinted polymer (MIP)-on-a-tip (MOT) electrochemical sensor for the highly sensitive quantification of LET in plasma. The miniature sensor combines a small pipette tip platform with a conductive matrix made from upcycled peanut shells and a selective MIP layer made through rapid electropolymerization of o-phenylenediamine. This design allows direct, in-tip measurement of LET in plasma without prior sample pretreatment. The MOT sensor showed a wide linear range (1.0-38.0 pM) for LET with outstanding sensitivity (LOD: 0.32 pM). When applied to human plasma, it achieved accurate results with an excellent recovery range (98.78-105.65 %), which shows that it could be a powerful tool for decentralized therapeutic drug monitoring and personalized medicine.