AbstractsBiology & Animal Science

Different hybrid nanoparticles (NPs), including FeM (M=Ni, Au, Pt, Pd) and Fe-biomolecules (biomolecule=glucose oxidase, p53p protein), have been synthesized by a surfactant-free, single-step electrochemical method. FeNi bimetallic NP systems have been chosen as the starting point of the present study. Shape evolution and phase transformation of FeNi NPs obtained by changing their composition is demonstrated. It has been shown that the shape evolution of NPs from concave cube to truncated sphere occurs concurrently with the phase transformation from bcc to fcc. In-situ formation of a very thin Ni-doped FeOOH outer layer and NiFe2O4 intermediate layer on the skin of the NPs is observed, the latter of which passivates the surface and dramatically enhances the air stability. Furthermore, bimetallic FeNi concave nanocubes with high Miller index planes have been obtained through controlled triggering of the different growth modes of Fe and Ni. Taking advantage of the higher activity of the high-index planes, mono-dispersed concave nanocages have been fabricated by introducing a material-independent electroleaching process. With the high-index facets exposed, these concave nanocubes and nanocages are found to be 10 and 100-fold, respectively, more active toward electrochemical detection of 4-aminophenol than cuboctahedrons which provides a label-free sensing approach to monitoring toxins in water and pharmaceutical wastes. In addition, the shape-dependent magnetic properties of a bimetallic system have been studied for FeNi NPs with well-defined concave cubic and octahedron shapes. The alloy composition was chosen to be close to that of Invar FeNi alloys (35% Ni content) but with concurrent presence of both bcc and fcc phases, in order to investigate the role of phase combination in controlling the magnetic properties. The role of the two phases in governing the magnetic properties has also been studied for both bulk and nanoalloys by large-scale density function theory (DFT) calculations using Vienna Ab-initio Simulation Package (VASP, Version 5.2), which provides a new complementary approach to understanding the magnetic properties of alloy materials. To extend the aforementioned method to other hybrid and bimetallic systems, FePt NPs with different compositions (Fe25Pt75, Fe30Pt70, Fe35Pt65) have been synthesized and their chemical sensing investigated for the electro-oxidation of vitamin C. The FePt alloy NPs are found to be superior catalysts for vitamin C electro-oxidation than Pt NPs and are significantly more selective for the detection of vitamin C against other common interference species, including dopamine, citric acid, uric acid, glucose, and NaCl. Enhancement in sensor performance can be attributed to the increase in specific surface area due to reduction of nanocrystallite size and to modification in the Pt electronic structure as a result of nanoalloying. We also synthesize bimetallic FeAu, FePd, and AuPt NPs and investigate their electrochemical properties for As(III) detection. The synergistic effect…