Inlaid Nd-substituted bismuth titanate nanoplates for protein immobilization and Nd-controlled electrochemical properties

Neodymium (Nd) substituted bismuth titanate (Bi 4− x Nd x Ti 3 O 12 , BNTO- x ) nanoplates inlaid one another were prepared by sol–gel hydrothermal method, which was explored for protein immobilization and biosensor fabrication. Comparative experiments witnessed that Bi 3+ ions in bismuth titanate (Bi 4 Ti 3 O 12 , BTO) were successfully substituted with Nd 3+ ions, and the electrochemical properties of the Hb–Chi–BNTO biosensors closely depended on the Nd 3+ ion content. With increasing the Nd 3+ doping content, the electrochemical performance of the Hb–Chi–BNTO- x biosensors showed regularly variable. Moreover, compared with the Hb–Chi–BTO and other Hb–Chi–BNTO- x biosensors, the Hb–Chi–BNTO-0.85 biosensor had more excellent electrochemical and electrocatalytic properties such as stronger redox peak currents (approximately three-fold), smaller peak-to-peak separation (50   mV), larger heterogeneous electron transfer rate (14.1   ±   3.8   s −1 ), higher surface concentration of electroactive redox protein (about 8.16   ×   10 −11   mol/cm 2 ), and better reproducibility and stability. The Nd-depended electrochemical properties of the Hb–Chi–BNTO biosensors may open up a new idea for designing third-generation electrochemical biosensors, and the BNTO-0.85-based biosensor is also expected to find potential applications in many areas such as biomedical, food, and environmental detection.