Investigation Of Electrochemical Sensing Based On Morphology Controllable Nanomaterials

With the rapid development of nanoscience and nanotechnology, the inctoudition of morphology controllable functionized nanomaterials into the investigation of electrochemical sensing, can achieve the fabrication and control of novel electrochemical sensing interfaces to slove the existing problems in environmental monitoring, early disease diagnosis and so on. It becomes one of the inevitable trends of electroanalytical chemistry’s development. In this thesis, chemical method, electrodeposition method and biological method were used to synthetize metal, nonmetal and composite nanomaterials with unique morphology and thirteen novel electrochemical sensors were also fabricated. Electrochemical behavior of redox proteins(enzymes) and the biocatalysis towards small molecular substances were investigated and new electeochemical analytical methods for the determination of H2O2, glucose, N2H4as well as NO2were established. These researches provided guidance for the investigation of the direct electrochemistry of proteins(enzymes) and enriched the research contens of electrochemical sensors and namomaterials. There are five chapters in the thesis, and the main contributions of the author are summarized and presented as follows:1. Three kinds of fonctionilized graphene(GE):IL-GE, AuNPs-GE. Fe3O4-GE were prepared by chemical reduction method, Nafion/Hb-IL-GE/CCE, Hb-IL-AuNPs-GE/CCE, Hb-Fe3O4-GE/CCE sensors were fabricated for the investigation of direct electrochemistry and electrocatalysis of Hb, thereby, new electeochemical analytical methods for the determination of H2O2were established. IL improved the stripping of GE from the electrode surface, AuNPs enhanced the interaction between GE and protein, Fe3O4not only overcome inherent defect of GE, but also improved stability and electrocatalytic performance. of the proposed electrode. Among them, Hb-Fe3O4-GE/CCE exhibited the best analytical performance for the determination of H2O2, the response time was less than3s and linearity range was1.5×10-6～5.9×10-4mol·L-1with a detection limit of5×10-7mol·L-1(S/N=3). It also showed good repeatability and stability.By controlling conditions of hydrothermal reactions, a new kind of carbon nanomaterial with comb-Like morphology (CLC) was prepared. Based on this, Hb/{PDDA-CLC/AuNPs}3/PDA/ITO sensor was fabricated by layer-by-layer assembling and employed for the investigation of electrochemistry behaviors of Hb, thereby, a new analysis method was established for the determination of H2O2. Under optimized experimental condition, the linearity range for the determination of H2O2was6.0×10-8～1.6×10-3mol·L-1with a detection limit of3.0×10-8mol·L-1(S/N=3). Furthermore, the biosensor also showed a fast response (within2s) and a high stability.i-Fe3O4of3D network was successfully prepared via a simple chemical precipitation at the gas/liquid interface with ammonia vapor. Based on this, a novel sensor was successfully fabricated for the determination of N2H4. Comparing with typical preparation method of Fe3O4,the gas/liquid interface reaction can take place without the protection of any inert gas and a film of i-Fe3O4floating at the interface was obtained. The sensor displayed a response time less than2s, a sensitivity of152μA·(1.0×10-3mol·L-1)-1·cm-2and the linearity of1.0×10-7～6.0×10-4mol·L-1with a detection limit of5.0×10-8mol·L-1(S/N=3).2. With the novel concept that coalition of replacement action and template assisted electrodeposition, PtNPs and PdNPs were prepared by electrodeposition, thereby, a new analysis method was established for the determination of N2H4. The results indicated that nanopore structure of nanoZnO effectively controlled the release of the hydrogen bubble to form PtNPs clusters with uniform pore size distribution, the addition of Ethaline, can restrain the hydrogen bubble on sacrificial templates to form highly decentralized PdNPs. Comparing with i-Fe3O4/CCE and PtNPs/nanoZnO/GCE, for the determination of N2H4, t-PdNPs/GCE had a lower detection limit of3.0×10-8mol·L-1(S/N=3).Co-GE and Cu-GE were preaprted by ultrasonic assisted eledtrodposition, Co-GE/GCE and Cu-GE/GCE were fabricated, thereby, new electeochemical analytical methods for the determination of N2H4and glucose were established. The results indicated that complexationmade the successive electrodeposition of GE and Co to form hierarchical flower-like Co grown on petalage-like GE. Based on this, the fabricated sensor showed high sensetivity of562.5μA·(1.0×10-3mol·L-1)-1·cm-2for the determination of N2H4; The addition of Ethaline led to GE and CuNPs electrodepose simultaneously and formed flower-like Cu-GE composite. Based on this, the fabricated sensor showed a lower overpotential of0.3V for the determination of glucose. The sensor displayed a response time less than3s, the linearity of5.0×10-6～9.0×10-4mol·L-1and9.0×10-4～1.1×10-2mol·L-1with a detection limit of1.0×10-6mol·L-1(S/N=3).One-pot electrodepostion was used to wrap Hb onto ITO and Hb-PANI/ZnO-AuNPs/ITO was fabricated for the investigation of direct electrochemistry and electrocatalysis of Hb, thereby, new electeochemical analytical method for the determination of H2O2was established. The results indicated the synergistic effects of ZnO, AuNPs and PANI made Hb keep the original bioactivity effectively. Comparing with H2O2mentioned above, the electron transfer rate was greatly increased, ks was4.4s-1.3. Gold dendrites(AuD) were synthesized with egg white as the soft template and a novel nitrite(NO2) biosensor was fabricated by assembly of a myoglobin (Mb)-L-cysteamine(Cys)-AuD biological hybrid. The results indicated diffusion limited aggregation processes lead to the formation of complicated shapes qualitatively similar to real dendrites. Compering with literatures, the sensor was high performance.It displayed the linearity of5.0×10-7～4.0×10-4mol·L-1with a detection limit of3.0×10-7mol·L-1(S/N=3), KappMwas2.0×10-4mol·L-1.Two kinds of glucose biosensors were fabricated by GOx biocatalytical induced deposition and accumulation of AuNPs on the surface of GOx-CLC/PGE and GOx/DNA-GE/GCE. The results indicated the synergistic effects of the advantages of biocatalysis itself, such as the accumulation, amplification effects and the signal amplification of CLC, DNA-GE and AuNPs, led to the high sensitivity and low detection limit of the fabricated biosensors. Compared with other methods, the glucose biosensors showed sensitivity that higher1.2-4000times of2.44×104μA·(1.0×10-3mol·L-1)-1and detection limit that lower one to three orders of magnitude of3.0×10-8mol·L-1(S/N=3).