Ferrocene-metal organic framework as a multifunctional electroactive bio-interface for immunosensing of lactoferrin...

Lactoferrin (LF) is an iron binding glycoprotein, whose accurate quantification is increasingly significant for health and food safety monitoring. Herein, an advanced electrochemical bioelectrode based on ferrocene-incorporated carboxymethyl-β-cyclodextrin metal-organic framework (Fe-CM-β-CDMOF) is synthesized for sensitive lactoferrin detection. The synergistic properties of CM-β-cyclodextrin and trimesic acid (BTC) produce a biocompatible scaffold that optimally enhances electron-transfer kinetics, retain mediators, and provide stability while ferrocene act as stable redox species used for signal amplification. The Fe-CM-β-CDMOF was characterized through Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Dynamic light scattering (DLS) and field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, atomic force microscopy (AFM) and each step of the sensor fabrication was observed using cyclic voltammetry (CV). The immunosensor was fabricated on graphite pencil electrode (GPE) using NHS/EDC chemistry to maintain biorecognition layer formation and retained bioactivity. Under the optimal conditions, the bioelectrode permitted to detect LF within the linear range of 1.0 х 10^-2 -1000.0 ngmL^-1, with a limit of detection 6.0 х 10^-3 ngmL^-1 and a response time of 45 min. The bioelectrode exhibited high selectivity, excellent reproducibility and stability over 12 days. The practical applicability of GPE/Fe-CM-β-CD-MOF/EDC-NHS/anti-LF antibody biosensor was demonstrated by detection of LF in milk and saliva samples, and good recovery values (98.0-102.0%) were obtained.