Polyfluorene-Based Bioconjugates for Selective Detection of Ferritin in Normal and Cancer Human Blood Serums

A new highly conjugated polymer–bioconjugate poly­[9,9-bis­(6′-adenine) hexyl)­fluorene-co-4,7-(2,1,3 benzothiadiazole)] (PFBT-A) is developed using the well-known Pd­(PPh₃)₄-catalyzed Suzuki cross-coupling polymerization reaction with a simple purification method. PFBT-A showed excellent sensitivity toward the iron containing metalloprotein and the well-known cancer biomarker ferritin with a detection limit as low as 0.164 nM (i.e., 71.05 ng/mL), which is much below the ferritin level observed in the blood serum of cancer patients. Detailed mechanistic study confirmed the presence of static ground state complexation and electrostatic interaction between the probe and the analyte, leading to quenching in fluorescence intensity of the probe. Real-time applications with the probe were performed in the unspiked serum samples of two normal people and two cancer patients (carcinoma valva and chronic myeloid leukemia) with significantly high ferritin content. Further analysis of PFBT-A in spiked normal blood serum samples showed good recoveries in the range of 102–102.5% with relative standard deviations (RSDs) within 1.07–1.16%, confirming the reliability and practical applicability of PFBT-A for ferritin detection in human blood serum. In the case of cancer blood serums, the recoveries were high, in the range of 105–109%, showing a high level of ferritin in cancer patients.