| Noble metal nanoparticles have special physical and chemical properties, which provide greatly potential applications in materials science, optical bio-sensing, biomedical diagnosis, development of cancer therapy drug, and disease treatment fields. This paper mainly reviews the latest progress for synthesis of the gold nanorods and their optical properties and applications on the LSPR sensing, molecular recognition and biomedical fields.(1) The chemical reduction was employed to prepare the gold nanoparticles and Au-Ag nanoparticles. By changing the amount of HAuCl4 solution and controlling of the mole fraction ratio of gold-silver, the gold and silver-gold composite nanoparticles were prepared with different mole fraction ratio of 2:1, 1:1, and 1:2.(2) Two different methods were used to synthesize gold nanorods. In the non-Ag+ system, with low solubility cetyltrimethylammonium bromide (CTAB) used as surfactant and ascorbic acid (AA) as weak reducing agent, the gold nanorods were synthesized by a seed mediated growth method. In the Ag+ system, with the Ag+ used as an inducer, high solubility cetyltrimethylammonium bromide (CTAB) as surfactant, and ascorbic acid (AA) as weak reducing agent, the gold nanorods were synthesized by a seed mediated growth method. As the result, CTAB concentration has played an important determining factor on the formation of gold nanorods. With the seeds and ascorbic acid increased, the aspect ratio of nanorods increases. Finally, two different gold nanorods growth mechanisms under the system were discussed.(3) Taking sodium citrate as reducing agent and silver nitrate as inducing agent, homogeneous gold nanorods sols were prepared by chemical reduction in this paper. DL-1,4-dithiothreitol (DTT) was first self-assembled on a flat gold plate electrode with a diameter of 3 mm. 3-mercaptopropionic acid was chosen to bind with gold nanorods to form molecular recognition biosensors. The prepared gold nanorods were characterized with UV-Vis and TEM. And their assembling processes were tested by cylic voltammetry.The EDC-DMAP as a nice catalyst of interaction between amino and carbonoxyl groups has been exploited. The nanobiosensor, based on the gold nanorods modified with activity increased, exhibited distinct optical properties of localized surface plasmon resonance (LSPR) in visible absorption region. The maximum adsorption amount of c-Myc monoclonal antibody molecule on the modified LSPR nanobiosensor with the nano film could reach 2.8μg/mL. The LSPR biosensor immobilized with c-Myc monoclonal antibody could be used for recognition of oncogene biomolecules such as MYC recombinant protein (P01) with a low linear response range of 5.2×10-3—0.69μg/mL and a detection limit of 3.1 ng/mL, showing its promising theoretical and applicable values on detection and diagnosis of malignancy.(4) Platinum nanoparticles (PtNPs) were prepared by using sodium borohydride as reductant. Polyvinyl- pyrrolidone (PVP) was used as protective agent to improve the stability of the platinum colloids. Glucose biosensors (GOD-PtNPs/GCEs) were formed in optimal conditions with glucose oxidase (GOD) immobilized membrane martrix, which was composed of platinum nanoparticles and polyvinyl butyral (PVB) with sol-gel method. In comparison with the electrode unmodified with PtNPs, the catalytic activity of the immobilization GOD was significantly enhanced by PtNPs, resulting in rapid electron transferring and nice reversibility of the electrochemical reaction. The proposed biosensor showed a good sensing performance for glucose at a linear range from 1.60×10-5 to 2.40×10-3mol/L, with a detection limit of 8.00×10-6 mol/L. The glucose biosensor possessed nice selectivity, reproducibility, stability and long lifetime with a recovery of 97.55 ~ 102.19 %, which can be well applied to determination of glucose in actual honey samples, showing its promising theoretical and applicable values on detection and diagnosis of diabetes mellitus. |
PDF Full Text Request