Zr-MOF functionalized nanochannels: Application to regenerative and sensitive electrochemical aptasensing platform

Solid-state nanochannels (SSN) have thrown open a new avenue for the construction of electrochemical biosensing platforms due to the fact that interaction between biomolecules occurred into the confined space can be monitored conveniently. Regeneration of the SSN is a necessary attempt to reduce bioassay costs and avoid deviations caused by the unidentical distribution of nanochannels. Herein, we constructed a renewable aptasensing platform derived from SSN functionalized with zirconium-based metal-organic frameworks (Zr-MOF). SEM images and XRD patterns demonstrated the successful growth of Zr-MOF crystals onto the surface of the nanochannels. The large surface area and rich metal center of Zr-MOF were conducive to the formation of Zr−O−P bonds with the phosphate group in the DNA skeleton through coordination reaction, hence providing a convenient way for the linkage of thrombin aptamer into the nanochannels. The flux of the redox probe [Fe(CN)6]3− in the nanochannels was applied to electrochemically monitor the aptamer-target interaction that occurred in the limited space. On this basis, the designed aptasensing platform could achieve quantitative determination for thrombin ranging from 10 fM to 10 nM with a detection limit of 4.0 fM. More importantly, the aptamer could be offloaded with free phosphate, resulting in regenerative Zr-MOF nanochannels which allowed the subsequent re-immobilization of fresh aptamer. RSD for 11 cycles of regeneration treatment was no more than 1.8%. The outstanding reusability of the nanochannels ensured a cost-effective, label-free, sensitive and accurate aptasensing platform.