A novel and ultrasensitive electrochemical immunosensor based on nanocellulose-TiCT@ZrO nano framework for the detection of ovalbumin.

A versatile and highly sensitive sensing platform based on nanocellulose/MXene/ZrO nano framework has been developed at the surface of a glassy carbon electrode (GCE) for detecting ovalbumin (Ova). To create this innovative nano framework, dialdehyde groups were introduced onto the surface of cellulose nanofibers (CNFs), which were then decorated with MXene nanosheets and nanostructured zirconia. Nanocellulose/MXene/ZrO2 nano framework was used as electrochemical mediator and immobilization environment that provided the large surface area and 197 % increment in the electrochemical signal which allowed the Ova detection in the femtomolar range. Ovalbumin antibody was immobilized on the surface of dialdehyde cellulose nanofiber through covalent bonding between amino groups of Ova and dialdehyde groups of CNFs. The assembly process of nano framework, anti-Ova, and Ova antigen were characterized using electrochemical approaches (CV and DPV). The fabricated immunosensor is further applied to DPV detection of Ova and it demonstrated a linear response to Ova antigen in the linear range of 0.01-1000 pg/mL. With optimal experimental conditions, the detection limit, quantification limit and sensitivity of Ova were found to be 1.1 fg/mL, 0.01 pg/mL and 0.1497 μA pg/mL cm, respectively. The fabricated immunosensor exhibited high selectivity, reproducibility, and interference resistance and achieved excellent recoveries in real food samples spiked with Ova, indicating its potential applicability in food safety monitoring.