Label-free electrochemical immunosensing of cystatin C base on aptamer/gold/MXene nanoribbons

Cystatin C (Cys C) is gaining prominence as a pivotal biomarker for evaluating gestational diabetes mellitus, a condition with profound implications for both maternal and fetal well-being. Herein, a facile and sensitive label-free electrochemical immunosensor for Cys-C was developed utilizing a modified electrode based on Ti₃C₂Tₓ MXene nanoribbons (TiC NRs) decorated with gold nanoparticles (Au NPs) (TiC NRs/Au) nanohybrids. Comprehensive characterization of the TiC NRs/Au hybrids was performed using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and electrochemical techniques. The Cys-C specific aptamer (Apt) was immobilized onto the modified electrode surface via the formation of the Au S bonds between the Au NPs and the thiolated Apt. Potassium ferrocyanide (K₄[Fe (CN)₆]) served as the electrochemical signal probe; binding of Cys-C to the immobilized Apt resulted in a measurable suppression of this probe's signal, thereby enabling target quantification. Following optimization of key assay parameters, the immunosensor demonstrated a broad linear detection range spanning 0.3 to 800 ng/mL and achieved a remarkably low detection limit of 0.1 ng/mL for Cys C, underscoring the significant clinical diagnostic potential of this novel sensing strategy. • A facile and sensitive label-free electrochemical immunosensor was developed for Cys-C. • The TiC NRs/Au nanohybrids was used to immobilize Apt. • The as-developed sensor exhibited superior detection performances. • The detection limit of Cys-C is low to 0.1 ng/mL.