| Non-specific adsorption(i.e.,fouling)is a prominent common problem in the application of biosensors to actual sample detection.Currently,physical,chemical,and biological antifouling strategies have been developed to minimize nonspecific adsorption.Though demonstrably effective,these have identified specific disadvantages.Using the synergistic advantage,several antifouling strategies can be combined into a multi-functional anti-fouling interface to obtain better antifouling effect.DNA nanostructures can prevent nonspecific adsorption through steric hindrance due to their unique conformation;the porous nanocomposites formed by bovine serum albumin(BSA)combined with nanomaterials prevent nonspecific absorption while enhancing electron transfer to the electrode surface.In this paper,DNA nanostructures and BSA nanocomposites were combined with other materials to construct different novel anti-fouling strategies on the surface of the screen-printed carbon electrode(SPCE).The hybrid synergistic antifouling effect is used to reduce nonspecific adsorption and realize rapid and sensitive detection of biomarkers in complex samples.The details are as follows:Part Ⅰ.Construction of DNA nanostructure/carboxyethyl-dextran bilayer antifouling interface and its application in rapid detection of Hb A1cBy combining the DNA nanostructure with the hydrophilic polymer carboxyethyl-dextran,the antifouling interface of DNA nanostructure/carboxyethyl dextran bilayer was constructed on the electrode surface.Combining the steric hindrance effect of rigid DNA nanostructure with the formation of a hydration layer on the surface of carboxyethyl dextran hydrogel to synergistic antifouling can better prevent nonspecific protein adsorption.In addition,polyvalent carboxyethyl dextran hydrogels can be used as scaffolds to immobilize capture probes of different molecular types(such as small molecules,DNA,and proteins)for detection of different target molecules.By immobilization of Hb A1 c antibody on the surface of carboxyethyl dextran hydrogel,the biomarker of diabetes Hb A1 c can be rapidly detected in 5% BSA,with the detection range of 4% ～ 12% and the detection limit of0.9%.Compared with the blank control electrode and the DNA nanostructure monolayer,it is proved that the constructed bilayer has better anti-fouling performance and more sensitive detection performance.The structure of DNA nanostructure/carboxyethyl dextran bilayer is stable,and the constructed biosensor can be used for the detection of biomarkers in complex samples.Part Ⅱ.Construction of nano-porous layer antifouling carbon biosensing interface and its application in rapid detection of Hb A1cBy combining the large surface-to-volume ratio and excellent electronic properties of multi-walled carbon nanotubes with the anti-fouling performance of BSA,the anti-fouling interface of nanoporous layer was constructed on SPCE surface through the cross-linking of glutaraldehyde.The size filtration of nanopore in porous layer and the anti-fouling of negatively charged BSA can effectively resist non-specific adsorption.The porous layer kept 92% of the original signal in 1% BSA and 88% of that in unprocessed human serum after 1-month exposure,respectively.Hb A1 c can be detected in undiluted serum by immobilization of Hb A1 c antibodies on the surface of the porous layer,with a linear range of 2 to 15% and a detection limit of0.4%.The sensitivity of the porous layer was 6 times higher than that of the bare SPCE interface.The constructed carbon resistant interface of the nanoporous layer is simple,stable and easy to operate,which provides potential support for the development of biosensors for the detection of complex samples.Part Ⅲ.Construction of nanoporous layer anti-fouling gold-carbon interface and its preliminary application in rapid detection of prostate specific antigenIn order to expand the antifouling interface for the detection of low concentration biomarkers,the porous layer antifouling carbon interface constructed in the Part Ⅱwas improved for the rapid and sensitive detection of prostate specific antigen(PSA),a serum marker of prostate cancer.The gold-carbon interface was constructed by sputtering on the surface of SPCE electrode,and then BSA,glutaraldehyde and multi-walled carbon nanotubes were coated on the surface of SPCE electrode to construct the nanoporous film antifouling gold-carbon interface.By immobilizing PSA antibodies at the interface,PSA can be rapidly detected in untreated serum in one step,with the detection range of 0.1 ～ 100 ng/m L.In summary,we used the synergistic advantage of several antifouling strategies to construct a novel antifouling interface in a multifunctional electrode sensing layer to reduce non-specific adsorption,which realized the rapid detection of biomarkers in complex samples.Electrochemical biosensors provide a new method for rapid and sensitive detection of biomarkers in real samples based on synergistic antifouling and disposable SPCE. |
