高分子聚合物-多壁碳纳米管复合物固定漆酶及其在玻碳电极上的直接电子迁移

采用不同结构的高分子聚合物与纯化的多壁碳纳米管(MWCNTs)共混的方法,制备得到聚合物非共价功能化多壁碳管复合物,测定了这些载体对漆酶(lac)的担载量、固定漆酶的比活力及稳定性.以固定漆酶的复合物修饰玻碳(GC)电极后,采用循环伏安法研究这些电极在无氧磷酸盐缓冲液(PBS)中的直接电化学行为及催化氧还原活力,粗略地测定了固定漆酶与电极间电子转移的速率常数.实验结果表明,当聚合物中含亲漆酶基团或能与漆酶活性中心发生相互作用的官能团时利于直接电子转移,而且复合物固定漆酶保持了游离漆酶的天然构象.这些电极中,lac/NIPAM-co-BPCP-M WCNTs/GC(NIPAM-co-BPCP:N-烯丙基-1-苯甲酰基-3-苯基-4,5-2H-4-甲酰胺基吡唑-co-N-异丙基丙烯酰胺)在无氧PBS中发生直接电子转移的式电位(605mV)更接近漆酶活性中心的式电位(580mV),具有较快的异相电子转移速率(0.726s-1),较高的漆酶担载量(103.5mg/g)和固定漆酶比活力(1.68U/mg),较高的催化氧还原能力(氧还原起始电位820mV,在650mV时的催化峰电流为85.5μA)以及良好的重复使用性和长期使用性.

Immobilization of Laccase on Multiwall Carbon Nanotubes-Polymers Composites and Their Direct Electron Transfer on Glassy Carbon Electrode

Composites of multi-wall carbon nano-tubes(MWCNTs) non-covalently functionalized by polymers with different structures were prepared through co-mixing purified MWCNTs and different polymers.These composites were used to entrap laccase(lac) molecules.The enzyme loading amount of carriers,the specific activity and stability of entrapped laccase on these carriers were determined.After coating glassy carbon(GC) electrodes with these composites,the direct electrochemical behavior of these laccase-based electrodes and their catalytic activity toward oxygen reduction reaction in deaerated phosphate buffer solution were investigated with cyclic voltammetry.The velocity constants of electron transfer between entrapped laccase molecules and electrode were also estimated.Experimental results indicate that the electron transfer could be favored when the polymer contains laccase-phlic functional group or groups which can interact with cofactor of laccase and laccases entrapped in composites retaining original conformation as free laccase.Among these laccase-based electrodes,formal potential of direct electron transfer occurred in lac/NIPAM-co-BPCP-MWCNTs/GC(NIPAM-co-BPCP:N-isopropylacrylamide-co-N-allyl-1-benzoyl-3-phenyl-4,5-dihydro-4-formamidopyrazole)(605 mV) is not only relatively closer to formal potential characterized T1 active site in laccase(580 mV) but also displays faster hetero-phase electron transfer velocity(0.726 s-1),higher enzyme loading(103.5 mg/g),improved immobilized laccase specific activity(1.68 U/mg),higher catalytic activity for oxygen reduction reaction(onset potential of oxygen reduction:820 mV,catalytic peak current at 650 mV:85.5 μA),good reusability and favorable long-term durability.