Photoelectrochemical Sensing System Based On Ligand Recognition And Anti-Fouling Interface For Detection Of CD44 And Folate Receptors

With the rapid development of semiconductor material research,photoelectrochemical?PEC?sensors have also developed rapidly,but PEC sensors also face great challenges when they are used in practical analysis.It is mainly due to the poor specificity and low sensitivity caused by the non-specific adsorption of non-target objects?proteins,polysaccharides and even cells?in biological samples to the sensor.In this paper,the PEC sensor with anti-fouling interface was constructed through polyethylene glycol?PEG?to solve the problems caused by non-specific adsorption.Based on the recognition between ligand and receptor proteins,a series of PEC sensors were constructed to explore the detection ability of the PEC sensor with anti-fouling interface to target objects.?1?Because the concentration of serum-soluble CD44 is closely related to the pathological process of cancer patients,it is necessary to develop a method that can specifically detect soluble CD44.In this work,a simple photoelectrochemical?PEC?method for sensitive detection of serum-soluble CD44 is proposed based on the construction of a hybrid anti-fouling coating on TiO₂ substrate.Hyaluronic acid?HA?and polyethylene glycol?PEG?are co-immobilized using a biomimetic one-step surface functionalization approach.The immobilized HA shows strong recognition abilities towards soluble CD44,and the synergistic anti-fouling effect achieved by the combination of PEG and HA improves the sensing specificity.Based on the inhibitory effect of CD44 recognition on the PEC signal of TiO₂substrate,a PEC biosensor is developed with a wide response range and a low detection limit.?2?Serum-soluble folate binding protein?FBP?is an important tumor marker and the development of simple biosensing method is highly needed.In this work,a PEC biosensor for the detection of FBP was proposed based on the construction of an antifouling interface and the unique ligand-protein recognition.The PEC sensing platform was prepared by the biomimetic polydopamine?PDA?coating on TiO₂ nanotubes arrays?NTAs?.TiO₂ NTAs has excellent photoelectric performance,and the porous structure provides more binding sites.Excellent antifouling performance was achieved by the conjugation of amino-group terminated8-arm poly?ethylene glycol??NH₂-PEG?.The incorporation of folic acid?FA?retains the antifouling property and showed recognition abilities towards FBP.The fabricated PEC biosensor showed good analytical performances.?3?Biomarker expression both in serum and on the cell surface is directly related to the pathological process of cancer.Based on the interaction between ligand and protein receptor,a label-free PEC biosensor with good antifouling ability for the detection of cancer biomarker CD44 was proposed.TiO₂ NTAs with three-dimensional?3D?structure was used as the substrate to improve the ability of biosensor to capture the target.Mercapto-terminated 8-arm poly?ethylene glycol??SH-PEG?is introduced to the surface by deposition of gold nanoparticles on TiO₂ NTAs,creating an antifouling molecular layer.The recognition ligand HA was functionalized by dopamine?DA?and introduced to the sensing surface based on the unique chelating interaction between catechol group and titanium atom.The constructed PEC biosensor not only has good identification and detection ability for the MDA-MB-231?CD44⁺?breast cancer cells,but also has good analysis and detection ability for soluble CD44.