Research On Electrochemical Sensor Of Biologically Active Substances Based On Modified Poly(styrene-butadiene) Flexible Fiber Membrane

Nanomaterials hold the unique optical,magnetic,electrical,and thermal properties,which make them pretty unique to be part of nanomaterial-based sensing technology for the broad applications.Nanomaterials can be roughly divided into four categories,such as nanopowder/nanoparticles,nanofiber,nanofilm,and nanoblock.Among them,nanofibers are one-dimensional nanomaterials with high specific surface area and aspect ratio.Nanofiber can be prepared by electrospinning technology and then made into the membrane.The membrane can be used to detect the bioactive species due to their unique advantages of fast detection speed and high detection sensitivity.As one of the most popular thermoplastic materials,polystyrene has many physical advantages,while similarly poly(styrene-butadiene)has both the rigidity of plastic and the elasticity of rubber with high mechanical strength,low production cost,and no pollution,which make it of great significance in the field of wearable sensor basic research.However,in order to make the membrane to be efficient in the sensing application,it needs the further modification to improve the electrical property.In this work,carbon nanomaterials,including carbon nanotubes and graphene,having the excellent electrical conductivity and high electron transmission rates are used to modify poly(styrene-butadiene)to achieve the conductive composite materials for sensing application.Gold nanoparticles having excellent biocompatibility and electrocatalytic activity are also introduced to prepare the composite as the electrochemical biosensors.This work is based on the electrospun poly(styrene-butadiene)flexible fiber membranes,which are then modified by carbon nanomaterials and gold nanoparticles.The as-modified electrocatalytic membrane was fabricated into electrochemical biosensors for the specific and sensitive detection of dopamine,serotonin and tryptophan.The specific work of this thesis includes the following aspects:1.A flexible carbon nanotubes modified poly(styrene-butadiene)for dopamine detectionIn this work,a flexible poly(styrene-butadiene)fiber membrane material was prepared by electrostatic spinning technology.The functionalized multi-walled carbon nanotubes(MWCNTs)were introduced to modify the fiber membrane to construct the MWCNTs/PEI/SSB composite conductive membrane material.The membrane was fabricated into an electrochemical sensor for the detection of dopamine(DA)in human serum and dopamine injection.The results showed that under the optimal experimental conditions,the linear response range of DA measured by differential pulse voltammetry(DPV)was 1-650?mol/L(R~2=0.996),and the detection limit(LOD)of DA(signal-to-noise ratio=3)was 0.062?mol/L.The prepared flexible fiber membrane material shows excellent mechanical properties and is expected to be applied in the wearable devices.The electrochemical sensor based on the conductive film can effectively reduce the interference caused by ascorbic acid and uric acid,and thus holds the good selectivity.2.Electrochemical detection of serotonin based on flexible reduced graphene oxide modified poly(styrene-butadiene)fiber membraneThe positively charged polymer electrolyte diethylene glycol phthalate diacrylate(PDDA)was previously modified on poly(styrene-butadiene)fiber membrane and then further modified with the reduced graphene oxide(RGO)due to the electrostatic interaction to finally prepare the RGO/PDDA/SSB composite.The poly(styrene-butadiene)fiber membrane was constructed as the RGO/PDDA/SSB flexible fiber membrane sensor and used to electrochemically detected serotonin.Under the optimal experimental conditions,a linear range of 1-300?mol/L and a detection limit of 0.82?mol/L were achieved.In addition,the sensor shows the good anti-interference ability.It can eliminate the interference of AA,UA,DA and other active substances,and realize the highly selective detection of serotonin.3.Gold nanoparticles modified poly(styrene-butadiene)fiber membrane for electrochemical detection of tryptophanIn order to further improve the conductivity of poly(styrene-butadiene)composite fiber membrane,gold nanoparticles were further modified onto poly(styrene-butadiene)flexibility membrane which was then used to selectively detect tryptophan(TrP).It is well-known that gold nanoparticles hold the good electrical conductivity,biocompatibility,and excellent catalytic performance.Its catalytic activity is various according to the size of the particles.In this work,gold nanoparticles were synthesized by reducing chloroauric acid with trisodium citrate,and the particle size was about 10 nm.The as-constructed sensor can selectively detect TrP in the presence of amino acids such as histidine,proline,and lysine.The good linearity was achieved in the range of 0.5-400?mol/L,and the detection limit was 0.43?mol/L.