Magnetic Janus micromotors for fluorescence biosensing of tacrolimus in oral fluids

• Published in: Biosensors & bioelectronics 2024-01, Vol.244, p.115796-115796, Article 115796
• Main Authors: Glahn-Martínez, Bettina, Jurado-Sánchez, Beatriz, Benito-Peña, Elena, Escarpa, Alberto, Moreno-Bondi, María C.
• Format: Article
• Language: English
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2023.115796

Tacrolimus (FK506) is a macrolide lactone immunosuppressive drug that is commonly used in transplanted patients to avoid organ rejection. FK506 exhibits high inter- and intra-patient pharmacokinetic variability, making monitoring necessary for organ graft survival. This work describes the development of a novel bioassay for monitoring FK506. The bioassay is based on using polycaprolactone-based (PCL) magnetic Janus micromotors and a recombinant chimera receptor that incorporates the immunophilin tacrolimus binding protein 1A (FKBP1A) tagged with Emerald Green Fluorescent Protein (EmGFP). The approach relies on a fluorescence competitive bioassay between the drug and the micromotors decorated with a carboxylated FK506 toward the specific site of the fluorescent immunophilin. The proposed homogeneous assay could be performed in a single step without washing steps to separate the unbound receptor. The proposed approach fits the therapeutic requirements, showing a limit of detection of 0.8 ng/mL and a wide dynamic range of up to 90 ng/mL. Assay selectivity was evaluated by measuring the competitive inhibition curves with other immunosuppressive drugs usually co-administered with FK506. The magnetic propulsion mechanism allows for efficient operation in raw samples without damaging the biological binding receptor (FKBP1A-EmGFP). The enhanced target recognition and micromixing strategies hold considerable potential for FK506 monitoring in practical clinical use.