Click Conjugation of Zwitterionic Peptide with DNA Strand: An Efficient Antifouling Strategy for Versatile Photoelectrochemical Aptasensor

Advanced antifouling biosensors have garnered considerable attention for their potential for precise and sensitive analysis in complex human bodily fluids. Herein, a pioneering approach was utilized to establish a robust and versatile photoelectrochemical aptasensor by conjugating a zwitterionic peptide with a DNA strand. Specifically, the branched zwitterionic peptide (BZP) was efficiently linked to complementary DNA (cDNA) through a click reaction, forming the BZP–cDNA conjugate. This intriguing conjugate exploited the BZP domain to create an antifouling biointerface, while the cDNA component facilitated subsequent hybridization with probe DNA (pDNA). To advance the development of the aptasensor, an upgraded PDA/HOF-101/ZnO ternary photoelectrode was designed as the signal converter for the modification of the BZP–cDNA conjugate, while a bipyridinium (MCEPy) molecule with strong electron-withdrawing properties was labeled at the front end of the pDNA to form the pDNA–MCEPy signal probe. Targeting the model of mucin-1, a remarkable enhancement in the photocurrent signal was achieved through exonuclease-I-aided target recycling. Such an engineered zwitterionic peptide–DNA conjugate surpasses the limitations imposed by conventional peptide-based sensing modes, exhibiting unique advantages such as versatility in design and capability for signal amplification.