The Preparation Of Conducting Polymer Microspheres And Using As Bioelectronic Interfacing Materials For Enzymatic Biosensors

The interfacing material between the biological and electronic part play a key factor for bioelectronic applications.The choice of good interfacing materials with special structure or construction is more important for the tight connection of these two parts which directly determined the possibility and performance of bioelectronic application,such as biofuel cells,enzyme based biosensors.Recently,many interfacing materials like conducting polymer and metal nanoparticles were developed due to the advancement of nanoscience,high-integrated chip technology and new material technology.An ideal interfacing material in biosensors device should be possess good affinity and stability for immobilizing the biomolecules or other materials?such as enzyme,AuNPs and PtNPs etc?,as well as good electrochemical performance for the fast electron transfer.On the other hand,the matrix should be had good processability,low cost and simple manufacture procedure in commercial production.The property of such interfacing materials and their structure will have significant impact in the practical application of biosensors.Therefore,the recent research mainly focus on finding and improving the proper matrix for biosensor applications.In this work,we describe a green and simple method for synthesize both PEDOT and PPY microspheres?PPy-MSs and PEDOT-MSs?which were obtained by employ CaCO₃ as a hard template for diffusion and polymerization of conducting polymer monomer,then using EDTA to remove the templates.Then the PPy-MSs and PEDOT-MSs were used as building blocks for the construction of heterojuction particles networks of PPy-MSs-PEDOT-MSs.In addition,an amperometric glucose biosensor was fabricated by in-situ reduction of Pt nanoparticles?PtNPs?on the PEDOT-MSs surface and adsorption of glucose oxidase?GOD?through opposites attract of surface charge,and end used for the detection of glucose.The morphology and chemical structure were characterized by means of scanning electron microscopy?SEM?,energy-dispersive X-ray spectrometer?EDS?,transmission electron microscopy?TEM?,Fourier transform infrared?FTIR?spectroscopy and size and zeta potential?Zetasizer?.The electrochemical performanceofheterostructuredPPy-MSs-PEDOT-MSsand Nafion/GOD-PtNPs-PEDOT-MSs/SPE glucose biosensors were evaluated by electrochemical measurement such as cyclic voltammograms,charge-discharge,amperometric detection.The detail researches are shown as follows:?1?The PPy-MSs and PEDOT-MSs were synthesized by using inorganic porous CaCO₃ as hard template for the loading of the Py and EDOT monomers that provide a university,green?surfactant and solvent free?and simple methods for the fabrication of PPy and PEDOT micro-particles?PPy-MSs and PEDOT-MSs?.The morphology and chemical structure of PPy-MSs and PEDOT-MSs were characterized by means of SEM,TEM,EDS,Particle size and zeta potentials analysis,and FTIR.Both PPy-MSs and PEDOT-MSs are displayed satiation,intact spherical morphology without observing significant collapsed shell structure,and maintains good dispersity with unfairly uniform particle size of 3.43±0.54?m and 3.18±0.52?m,respectively.Moreover,PPy-MSs shows a smooth and compact surface morphology with a negative zeta potential value of32.6±11.0 mV;PEDOT-MSs shows a rough and loose surface morphology with a positive zeta potential value of 14.7±7.01 mV.Electrochemical methods were used to evaluate the electrochemical properties.Both PPy-MSs and PEDOT-MSs shown better electrochemical capacitive performance than bulk synthesized random structured PPy and PEDOT,the highest improvement were 10 times and 2.3 times,respectively.?2?Studying the relationship between conducting polymer morphology and electrochemical properties from two different structure level.1)the comparation of electrochemical properties with single structure changing between PPy-MSs and random structured PPy,PEDOT-MSs and random structured PEDOT;2)the comparation of electrochemical properties with organized structure changing between heterostructured PEDOT-MSs-PPy-MSs and separated PEDOT-MSs/PPy-MSs?1:1?.Electrochemical methods were used to evaluate the electrochemical properties.The capacitance of PPy-MSs is increase by 1.7⁷.3 times compare with PPy at different scan rate.The capacitance of PEDOT-MSs was increase to 1.6².1 times compare with PEDOT at different scan rate.The capacitance of heterostructured PEDOT-MSs-PPy-MSs was increase to 1.25².07 times compare with separated PEDOT-MSs/PPy-MSs.?3?An amperometric glucose biosensor was fabricated by in-situ reduction of PtCl₄^2-to Pt nanoparticles?PtNPs?on the PEDOT-MSs surface for the formation of PtNPs-PEDOT-MSs and then adsorb glucose oxidase?GOD?through opposites charge attraction on their surface.The final glucose biosensor was based on screen printing electrode?SPE?.Then Nafion/GOD-PtNPs-PEDOT-MSs/SPE glucose biosensor was used for the detection of glucose.The morphology and chemical structure of PtNPs-PEDOT-MSs and GOD-PtNPs-PEDOT-MSs were characterized by means of SEM,EDS,FTIR and zeta potential.The glucose biosensors performance ware evaluated by electrochemical measurement.The results show that abundant of PtNPs are uniform distribute on the PEDOT-MSs surface with a diameter around 50nm,and the PtNPs-PEDOT-MSs shows a negative zeta potential value of 5.623±0.84mV.The GOD-PtNPs-PEDOT-MSs shows a little bit blurry surface image because of the insulate enzyme coating.However,the PtNPs still can be distinguished clearly from the PEDOT-MSs surface through the thin enzyme film,and also shows more negative zeta potential value?18.87±1.45 mV?compare with PtNPs-PEDOT-MSs,indicating GOD-PtNPs-PEDOT-MSs adsorb a large number of GOD?pl 4.2,here test solution is PBS pH 7.4?.The highest adsorbing capacity is 0.205mg GOD/mg PEDOT-MSs.the Nafion/GOD-PtNPs-PEDOT-MSs/SPE glucose biosensor showed a linear range from 0.1to 7×10^-33 mol/L?R²=0.9949?with a sensitivity of 131.5?A/mM/cm²,and a detection limit of 1.37×10^-6 mol/L?3×SD/sensitivity?.The apparent Michaelis–Menten constant(K_m^app)was calculated to be 7.3×10^-33 mol/L.Moreover,the biosensor exhibited good anti-interferent ability and stability.It provides a promising approach for green synthesis of processable GOD-PtNPs-PEDOT-MSs composite for further fabrication of sensitive and efficient electrochemical glucose biosensors in commercial level.