| Hemoglobin(Hb)has been widely researched for constructing novel electrochemical biosensors in recently years due to its properties similar to enzymes,the heme prosthetic groups of which are useful to detect the Oxygen-containing substances such as H2O2 and Na NO2.Electrospinning is an effective technology to prepare nanofibers with unique properties,such as high specific surface area and high porosity,which is found in preparation of novel electrochemical biosensors.Accordingly,in this paper,electrospun Hb/MWNTs-gelatin modified electrodes was prepared using electrospinning,and the direct electron transfer between Hb and electrode and the electrocatalytic performance for the substrate were investigated.The aim of this study is to prepare a novel electrochemical biosensor with higher sensitivity.The main results in this study are shown as follows:First,the co-electrospun Hb/MWNTs-gelatin nanofiber modified electrode was prepared using traditional electrospinning technology.The three-dimensional porous structure of the obtained modified electrode surface was beneficial for the direct electron transfer between Hb and electrode.The apparent heterogeneous electron transfer rate constant(ks)was calculated as(55.27±0.042)s-1.Besides,this modified electrode has a good electrocatalytic performance for H2O2 and Na NO2.The minimum detection limits of this modified electrode to H2O2 and Na NO2 were calculated as(0.0156±0.0007)μM and(0.256±0.0034)μM,respectively.The Michaelis-Menten constants(Kmapp)were calculated as(0.306±0.0013)m M and(4.137±0.014)m M,respectively.Then,the coaxial electrospun Hb/MWNTs-gelatin nanofiber modified electrode was prepared using coaxial electrospinning technology.The nanofibers of the obtained modified electrode have an obvious core-shell structure,the outer layer of which was Hb and the inner layer of which was MWNTs-gelatin.The direct electron transfer between the Hb and electrode was achieved by Hb fixed in nanofibers and the apparent heterogeneous electron transfer rate constant was calculated as(221.62±0.56)s-1.Moreover,this modified electrode has a good electrocatalytic performance for H2O2 as well.The minimum detection limit of this modified electrode to H2O2 was(0.0039±0.0003)μM and the Michaelis-Menten constant was calculated as(0.272±0.0014)m M.Last,the application performance of the electrospun Hb/MWNTs-gelatin nanofiber modified electrode electrochemical biosensor was investigated.The standard H2O2 and Na NO2 solution was detected by both co-electrospun and coaxial electrospun Hb/MWNTs-gelatin nanofiber modified electrode electrochemical biosensor with an accuracy of more than 87 %,indicating a certain availability of th electrochemical biosensor.Besides,the electrochemical biosensor had an accuracy of more than 86 % without interference from other substances when were applied to detect H2O2 and Na NO2 concentration in simulated body fluid and H2O2 concentration in standard milk and vegetable solution.It is indicated that the electrospun Hb/MWNTs-gelatin nanofiber modified electrode electrochemical biosensor has a good application prospect. |
