Application Of Chemical Modification Technology In Silicon Nanowire Serum Potassium Ion Sensor

Potassium is one of the important elements to maintain the physiological functions of the human body.It plays an important role in many biological processes such as nerve transmission,blood pressure and pH adjustment,enzyme activation and collagen formation.The K~+concentration in healthy people is 3.5 mmol/L?5.5 mmol/L.Abnormal K~+concentration can cause symptoms such as muscle cramps or weakness,nausea,diarrhea,frequent urination,dehydration,paralysis,and changes in heart rhythm.The conventional detection methods of K~+include flame photometry,ion selective electrode method,drying method,mass spectrometry,colorimetric method,etc.,but these methods have problems such as inability to detect in real time and low sensitivity.In recent ten years,the silicon nanowire field-effect transistor(SiNW-FET)biosensor has the advantages of both nanomaterials and field effect devices.It can respond to changes in electrical signals caused by the combination of molecules on the surface of silicon nanowires.It has high sensitivity,strong specificity and label-free features,and has been applied to the detection of proteins,ions,cells,viruses,etc.However,due to the influence of the semiconductor Debye screening effect,the SiNW-FET biosensor has encountered a bottleneck in the direct detection of target molecules in physiological solutions,and it is difficult to achieve the detection of target molecules in high ionic strength solutions.In addition,uncharged or weakly charged target molecules have very little effect on the semiconductor channel,and the target cannot be effectively measured.These two aspects greatly limit the clinical application of SiNW-FET biosensors.This article focuses on overcoming the influence of Debye screening effect and weak charge limitation,and chemically modifying the surface of SiNW-FET biosensor.Based on the special folding structure changes of common single chain aptamers,the coupling can produce high work function Au nanoparticles with nanowire channel current amplification,breaking the detection limit of SiNW-FET biosensors in physiological solutions,improving device sensitivity and constructing A biosensor used to detect K~+in serum samples.The main research contents of this article are as follows:1.The single chain aptamer that can undergo folding changes is modified on the surface of the SiNW-FET biosensor through 3-aminopropyltrimethoxysil ane,propyltrimethoxysilane,1-ethyl-3-(3-dimethylamino-propyl)carbodiimide hyd-rochloride and N-hydroxysulfosuccinimide to achieve high sensitivity and high specificity detection of serum K~+.The results show that the SiNW-FET biosens or modified with single-stranded aptamer can effectively overcome the influence of the Debye screening effect,and has high specificity and sensitivity to K~+,with a detection limit of 1 fmol/L.2.In view of the challenges of the SiNW-FET biosensor used in the detection of uncharged target molecules,the scheme was optimized.The K~+single chain aptamers are coupled to high-power Au nanoparticles,and then modified on the surface of the SiNW-FET biosensor.When the target molecule specifically binds to the aptamer,it causes the aptamer to undergo a folding change,causing the Au nanoparticles to approach the surface of the silicon nanowire.Due to the large difference between the work function of Au and Si,the work function of the liquid gate fluctuates,which causes the threshold voltage of the device to drift,and the current of the SiNW-FET biosensor changes significantly,realizing highly sensitive detection of uncharged target molecules.Compared with the detection method of single chain aptamers modified SiNW-FET biosensor surface,this method has high sensitivity,and is very helpful for the detection of uncharged target molecules.