Synthesis of Cu(II)-loaded polydopamine to construct fluorescence sensor for detection of cTnI from myocardial infarction

High-performance detection of cTnI possesses great significance for diagnosis of myocardial infarction. In this work, two kinds of lower-dimensional Cu(II)-loaded polydopamines were synthesized via in-situ polymerization of dopamine for the first time using Cu-pBDC MOFs and Cu-aBDC MOFs as templates. The obtained Cu-ppDA nanosheets and Cu-apDA nanoribbons maintain the original structure of MOFs and exhibit the advantages of large specific surface area and metal coordination effect, which efficiently enhances the adsorption of single-stranded aptamer DNA probe via π–π stacking. Energy transfer from FAM-Apt probe to Cu(II)-loaded pDA occurred, resulting in the fluoresce quenching. The inference of target cTnI assembles with FAM-Apt probe and the releases from FAM-Apt/Cu-ppDA or FAM-Apt/Cu-apDA systems, leading to the fluorescence recovery. This approach enables a simple, rapid, sensitive, and specific detection method for cTnI. By contrast, FAM-Apt/Cu-ppDA system shows a lower LOD than that of FAM-Apt/Cu-apDA. Furthermore, the successful implementation of these two fluorescent sensors for the detection of cTnI in serum samples obtained from mice with myocardial infarction has been demonstrated. The outcomes of this detection aligned with those achieved through the ELISA method, suggesting their promising potential for practical application in early screening for myocardial infarction.