A ratiometric fluorescence imprinted sensor based on quantum dots and boronic acid-functionalized MOF for detection of transferrin

Sensitive and rapid detection of transferrin (TrF) is useful in maintenance of human health. A ratiometric fluorescence imprinted sensor based on nitrogen co-doped carbon dots, red cadmium telluride quantum dots, and boronic acid-functionalized MOF (N-CDs/r-CdTe@MOF-B(OH)2@MIP, or NTZ@MIP) for the detection of TrF was constructed via the sol-gel process. Boric acid groups in the MOF-B(OH)2 carrier improved covalent binding to TrF through affinity interactions. MOF-B(OH)2 also provided a large specific surface area and porosity that increased the loading of quantum dots (QDs) and improved mass transfer efficiency and analytical sensitivity. NCDs and r-CdTe acted as fluorophores that emitted at 448 nm and 642 nm, respectively, in the presence of TrF, which facilitated ratiometric fluorescence detection. Under optimized conditions, TrF could be detected in the range 0.05-15 mu M, with a lower limit of detection of 0.025 mu M. The NTZ@MIP sensor produced satisfactory results in the analysis of TrF-fortified samples of human urine and serum, with recoveries of 93.2 % and 99.6 %, respectively. A smartphone-based TrF sensing platform using NTZ@MIP was also designed and achieved satisfactory results, suggesting that this ratiometric fluorescence imprinted sensor has promising applications in on- site detection of TrF.