Fabrication Of Nanomaterials Composites Based Sensing Interface And Electrochemistry/Surface Plasmon Resonance Investigation

In this paper, various nanomaterials composites, which combined novelmetal nanoparticles (gold nanoparticles, AuNPs), carbon nanotubes (CNTs) withpolymers (poly-o-phenylenediamine, PoPD), chitosan (CHIT) androom-terperature ions liquilds (RTILs), have been prepared and used to fabricatethe sensing interface for application in biosening and cell direct electrochemistry.The morphologies, structures and electrocatalytic properties for biomolecules(NADH) of the resulting nanomaterials composites modified electrodes havebeen investigated by SEM, TEM, FTIR, EDS, surface plasmon resonance(SPR),CV, square wave voltammetry and electrochemical impedance spectroscopy(EIS). The electrochemical/surface plasmon resonance biosensors based onthese nanomaterials composites have been fabricated and the application ofthese nanomaterials composites modified electrode in direct electrochemistry oftumor cell is also evaluated. The main work is summarized as follows:1. The potential applications of nanomaterials in bio-electrocatalysis,biosensing and direct electrochemistry of cells have been introduced indetails. On the other hand, the principle and the application ofelectrochemical surface plasmon resonance (ESPR) in biosensing have beenbriefly reviewed.2. The poly-o-phenylenediamine (PoPD) nonconducting film was prepared byelectro-polymerization on glass/gold film substrate and gold nanoparticles(AuNPs) were assembled on the surface of PoPD film, which used as anovel matrix for developing a simple and sensitive label-free immunoassayfor the detection of human immunoglobulin G (IgG).Electrochemical-surface plasmon resonance (ESPR) method was used toprovide the real-time information about the polymer film growth, assembling of gold nanoparticles, anti-human IgG antibody (anti-hIgG)immobilization and the antigen-antibody interaction. The resultsdemonstrated that the use of gold nanoparticles and PoPD film couldenhance the sensitivity and anti-nonspecific binding of the resultingimmunoassay electrode. The immunosensor could detect the hIgG with adetection limit of 0.1μg mL^-1 and a linear range of 0.8 to 38.5μg mL^-1. Thereproducibility and preliminary application of anti-hIgG/PoPD/AuNPs/Auelectrode for detection of hIgG was also evaluated.3. An electrochemical-sensing platform was developed based on theintegration of room-temperature ionic liquids (1-butyl-3-methylimidazoliumtetrafluoroborate, BMIM·BF₄) and multi-walled carbon nanotubes(MWNTs)with polymeric matrix (chitosan, CHIT). The resulting composite wereinvestigated and characterized by FTIR, TEM, SEM, EDS andelectrochemical methods. The BMIM·BF₄/MWNTs/CHIT have gooddispersibility in aqueous solution and can form a relative uniform film withunique structure. Electrochemical studies suggested that theBMIM·BF₄/MWNTs/CHIT composite system provided a synergisticaugmentation on the voltammetric and amperometric behaviors ofelectrochemical oxidation of NADH, which indicated by the decrease of thepeak potential of NADH oxidation and the improvement of amperometricresponse. Additionally, the BMIM·BF₄/MWNTs/CHIT/GC electrode showsgood analytical performance such as low detection limit(0.06μM), goodregeneration and anti-fouling properties for determination of NADH. Thisnanomaterials-based composite may be used as electrochemical transducersand have potential application for designing a variety of NAD⁺-dependentelectrochemical biosensors.4. Combining the large surface area, good electrocatalytic activity ofmulti-walled carbon nanotubes (MWNTs) with the advantages of poly-L-lysine (PLL) in cell immobilization, improving the dispersing ofCNTs in aqueous solution and electrode preparation, the MWNTs/PLLcomposites were prepared in this paper and used for immobilization ofhuman breast cancer cells (MCF-7) and its electrochemical propertiesinvestigation. The morphology and structure of MWNTs/PLL werecharacterized by SEM and FTIR. The electrochemical property andbio-compatibility of MWNTs/PLL/GC electrode, the electrochemicalresponse performance of MCF-7 cells at MWNTs/PLL/GC electrode wereinvestigated by CV and square wave voltammetry in details. The effect ofanti-cancer drug (adriamycin) on the electrochemical response of MCF-7was also evaluated. The results demonstrated that the MWNTs/PLL hasgood dispersibility in aqueous solution and can form uniform film; theresulting MWNTs/PLL/GC electrode is favorable to maintain the activity ofMCF-7 cells and has good bio-compatibility. The MCF-7 cells have animproved electrochemical voltammetric response at MWNTs/PLL/GCelectrode and the electrochemical voltammetric response of MCF-7 cellswas inhibited after the MCF-7 cells treated with anti-cancer drug. TheMWNTs/PLL composites, as a biomaterial with good electrocatalyticactivity and bio-compatibility, may have good potential application in cellelectrochemistry and in vitro assessment of the anti-cancer drug activity.