A novel double-door-opening sensor for visual determination of cardiac troponin I based on DNA hydrogel and bimetallic nanozyme

Cardiac troponin I (cTnI), as a cardiac biomarker, holds significant importance in the diagnosis of acute myocardial infarction. However, the current detection methods mostly require specialized personnel and large analytical instruments, making it difficult to achieve convenient and on-site testing. This situation leads to delayed disease diagnosis and treatment, that increases patient suffering, and reduces the cure rate. This strategy presents the development of a portable visual DNA hydrogel colorimetric sensing platform based on a smartphone. Utilizing dual-mode detection with ultraviolet signals and solution colorimetry, the platform achieves ultra-sensitive and real-time detection of cTnI. Furthermore, optimization of detection conditions, such as the amount of polyacrylamide, reaction time, aptamer concentration, encapsulation of the nanozyme, incubation time, and reaction temperature, were performed based on this platform. The proposed ultraviolet and visual detection platforms exhibited good linear relationships with the signal within the ranges of 0.003 ng mL⁻¹ to 10.00 ng mL⁻¹ and 0.01 ng mL⁻¹ to 7.00 ng mL⁻¹, with detection limits of 2.57 pg mL⁻¹ and 0.013 pg mL⁻¹, respectively. Additionally, utilizing 3D printing technology, a portable detection device was designed and employed for the detection of cTnI concentrations in human serum samples. Whatever in the initial and spiked samples, the results showed high sensitivities. The sensitivity and convenience of the sensor in detecting cTnI make it promising for home testing of patients, with broad market prospects.