Portable biosensor for cardiac Troponin I based on the combination of a DNA walking machine and a personal glucose meter

Recently, advances in the development of portable biosensors for detection of cardiac Troponin I (cTnI) have been made, yet complex recognition elements, expensive preparation costs, and limitations in quantification have hampered their widespread application. In present study, we have developed a portable biosensor for on-site detection of cTnI, taking advantage of the signal amplification function of a DNA walker and a low-cost personal glucose meter (PGM) and developed a new time-saving method for protein DNA coupling. In the presence of the target, the walking particle (WB) rolls rapidly along the surface of the track particle (TB), releasing a short DNA fragment labeled with invertase. Invertase catalyzes the hydrolysis of sucrose to glucose, which is quantified using a PGM. DNA Walker achieves recycling by regulating DNA stepwise movement by DNA nicking endonuclease (Nb.BbvCI). Under optimal conditions, the limit of detection (LOD) for cTnI was 0.001 ng/mL (S/N = 3), which is below the current acute myocardial infarction (AMI) detection standard (40 pg/mL). In addition, we validated the versatility of the platform by quantifying the RNA. With these features, the Recycling Walker-cTnI-Glucometer (RWCG) strategy was eventually applied to clinical serum, which indicates their important potential for early clinical diagnosis and treatment and trace biological sample detection.