Paper/PDMS-based Electrochemical Biosensors Based On MOF Were Applied For The Detection Of Biomolecules

The detection of biomolecules plays an important role in health management and disease prevention.Electrochemical analysis methods have the advantages of low cost,simple,fast operation and high specificity,which have broad application prospects in the detection of biomolecules.At first,traditional biosensors were often built based on rigid electrodes such as glass-carbon electrodes and ITO electrodes,which are relatively expensive and difficult to bend.In recent years,with the rapid development of electrochemical technologies,the detection of biomolecules is no longer limited to sensors constructed based on conventional rigid electrodes.Flexible electrodes and integrated micro-electrochemical sensors have gradually become new research hotspots of electrochemical biosensors because of their flexible and portable characteristics.Among them,the electrodes based on paper or polydimethylsiloxane(PDMS)are easy to integrate and have high mechanical flexibility.In this paper,PDMS and cellulose paper as flexible substrate,carbon nanotubes(CNT)as conductive material and MOF as catalytic material,and applied in biomolecular detection.The specific research contents are as follows:Part one A stretchable electrochemical biosensing platform based on Ni-MOF composite/Au nanoparticles coated carbon nanotubes for real-time monitoring of dopamine release from living cellsOur stretchable flexible electrochemical sensor was developed based on the Ni-MOF composite/AuNPs/CNTs and applied in the real-time detection of dopamine(DA)released from live C6 cells.Briefly,using the efficient one-step calcination method,the Ni,NiO and carbon frames were introduced into the two-dimensional Ni-MOF nanosheet surface to obtain the required Ni-MOF composite.The flexible electrochemical sensors obtained by depositing the composite on PDMS films had excellent electrochemical properties with a linear range of 5.0×10-8-1.5×10-5M and a sensitivity of 1250 mA·cm-2·M-1.Moreover,the flexible electrode also showed good cell compatibility and enabled real-time monitoring of DA released by C6 cells in natural and stretched states.This indicates that our newly designed flexible Ni-MOF composite/AuNPs/CNTs/PDMS(NACP)film electrode is promising in the detection of chemical signals released by cells and living organisms.Part two Flexible paper-based Ni-MOF composite/AuNPs/CNTs film electrode for HIV DNA detectionCNT/PVA solution and Ni-Au composite were deposited on the prepared cellulose film by vacuum filtration and droplet coating method,and finally the Ni-Au composite/CNT/PVA(CCP)film electrode was obtained.Compared with the single CNT/PVA film electrode,the CCP thin film electrode has a larger specific surface area,which can provide a certain amount of hydrogen bond source.The interaction between MOF and single-stranded DNA further improves the sensitivity of detecting target DNA.In addition,methylene blue(MB)as an indicator,the changes of its peak current were compared before and after the hybridization with HIV DNA.The results showed that the CCP electrode had a good sensing performance,with a linear range of 1.0×10-8-1.0×10-6M and a low detection limit of 1.3 nM.Our flexible CCP film electrode prepared could detect the target HIV DNA even in a complex serum samples.Part three Paper-based Ni-Co MOF electrochemical biosensor for tumor POC detectionIn this work,graphene nanosheet was fully printed onto the surface of polyethylene terephthalate(PET)as the GNP electrode.The Ni Co-based metal-organic framework(Ni-Co MOF)and carbon nanotubes(CNT)were modified to the GNP electrode and developed as an electrochemical immunosensor for quantitative detection of alpha-fetoprotein(AFP).After the immune reaction,the immune complexes formed on the electrode surface hindered the catalytic properties of the MOF,thus the electrochemical signal of MOF/CNT/GNP electrode greatly reduced.The variation of current signal on MOF/CNT/GNP electrode was monitored before and after incubation with AFP by the differential pulse voltammetry(DPV)method.Electrochemical measurements demonstrated that our immunosensor displayed a low detection limit of 0.14 ng/mL with a linear range of 1.0×10-9-2.0×10-7 ng/mL.For constructing highly integrated electrochemical analytical device,the filter paper was used as a substrate to assemble the immunosensor,which greatly reduced the cost of electrode preparation.Our designed Ni-Co MOF paper-based electrochemical biosensor has the advantages of low cost,high stability,easy to prepare,and has great application potential in personalized diagnosis of disease.