On-line coupling of millimeter size motors and chronoamperometry for real time bio-sensing of branched-chain amino acids in maple syrup urine disease clinical samples

Abstract

Abstract Here, the on-line coupling of millimeter size motors (m-motors) and chronoamperometry for real time bio-sensing of branched-chain amino acids ( l -b-AAs) in maple syrup urine disease (MSUD) clinical samples is proposed. Marangoni effect for controlled mixing and delivery of active enzyme for substrate digestion and subsequent electrochemical sensing is conveniently explored. To this end, an integrated cell device, which includes reservoirs for motors movement and electrochemical detection, was fabricated. l -amino acid oxidase (LAO)-loaded m-motors just by capillarity without any coating chemistry are used for the enantiomers selective recognition, and then the hydrogen peroxide released from enzymatic reaction is electrochemically monitored at −0.20\u2009V using copper microwires as exclusive transducers. The inherent enzyme m-motor features – “self-micro mixing” and the continuous release of fresh and free enzyme-, not only avoided the use of external stirring or the enzymatic physical adsorption or chemical bonding to the electrode; but a dramatic decreasing of analysis times (just 200\u2009s vs. 25\u2009min without motors, yielding only a 70% of the m-motor signal). In addition, an excellent accuracy (Er l -b-AAs determination in clinical samples from patients previously diagnosed by a reference center was also obtained. We envision future opportunities for this approach to be a potential point of care (POC) testing device, because of its rapid response, simplicity, selectivity and sensitivity; becoming into another step facing towards the challenges of rare disease diagnostics.