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 ± 3.8s(-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.

Solution-phase synthesis of metal and/or semiconductor homojunction/heterojunction nanomaterials.

The design and architecture of programmable metal-semiconductor nanostructures with excellent optoelectronic properties from metal and semiconductor building blocks with nanoscale dimensions have been a key aim of material scientists due to their central roles in the fabrication of electronic, optical, and optoelectronic nanodevices. This review focuses on the latest advances in the solution-phase synthesis of metal and/or semiconductor homojunction/heterojunction nanomaterials. It begins with the simplest construction of metal/metal and semiconductor/semiconductor homojunctions, and then highlights the synthetic design of metal/metal and semiconductor/semiconductor heterojunction nanostructures with different building blocks. Special emphasis is placed on metal/semiconductor heterojunction nanomaterials, which are the most challenging and promising nanomaterials for future applications in optoelectronic nanodevices. Finally, this review concludes with personal perspectives on the directions for future research in this field.

Synthetically directed self-assembly and enhanced surface-enhanced Raman scattering property of twinned crystalline Ag/Ag homojunction nanoparticles.

A synthetically directed self-assembly strategy to the aqueous-phase synthesis of twinned crystalline silver/silver homojunction nanoparticles (Ag/Ag HJNPs) is demonstrated. In the self-assembly, ethylenediamine tetraacetic acid disodium (EDTA) and solution pH values play a crucial role in the formation of Ag/Ag HJNPs while the sizes of Ag nanoparticles (NPs) in the Ag/Ag HJNPs depend on the reductant concentrations of ascorbic acid. Surface-enhanced Raman scattering (SERS) measurements indicate that the SERS intensity acquired from the Ag/Ag HJNP colloidal solution is about 200 times stronger than that obtained from isolated Ag NP colloid solution. The plasmonic and SERS behaviors of Ag/Ag HJNPs were simulated by discrete-dipole approximation (DDA) and three-dimensional finite-difference time domain (3D-FDTD) methods, respectively. Theoretical calculation results disclose that surface plasmon resonance (SPR) properties of the Ag/Ag HJNPs are different from those of isolated Ag nanospheres, and their maximal SERS enhancement is about 2 orders of magnitude higher than that of isolated Ag nanospheres, which is in good agreement with the experimental results. The extra SERS enhancement can be explained by the hot spots at homojunction structures between Ag particles because of near-field coupling effect.