The aspect ratio(AR)is one of the most intriguing parameters of gold nanorods(GNRs),which plays an important role in determining localized surface plasmon(LSPR)properties.Instead of conventional imaging techniques,the optical extinction spectroscopy(OES)method has been developed for allowing fast statistically measuring the average AR under static approximation.In this work,combining with the previous achievements in spectroscopic technique,we further analyze the effects of gold dielectric function and near distance dielectric sensitivity.The former may reflect possible dielectric loss of real Au samples from ideal single crystalline.The latter reflects the cetyltrimethylammonium bromide(CTAB)adsorption on the surface of GNR induces different LSPR shifts below and above critical micelle concentration(CMC).However,their effect on the determination of AR has not been evaluated in OES method.The average AR measurements as a function of absorbance of CTAB-GNRs and LSPR maximum below the CMC were studied.Our results indicate that after considering these factors,the mean ARs obtained from spectroscopic techniques are closer to those obtained from imaging techniques.
An important and difficult issue is simultaneously identifying the detailed locations of various molecules on the cell surface, as this identification requires a synergistic effect between more than one molecule in a living cell. Au nanoparticles (NPs) with different shapes can be readily recognised under low vacuum scanning electron microscopy (lvSEM). Anisotropic Au nanorods (NRs) possess unique surface plasmon resonance (SPR) properties, which can be further utilised for two photon luminescence (TPL) and other optical imaging techniques. In this paper, Au NRs and Au nanooctahedra (Au NOs) are introduced as biomarkers for ICAM-1 and Integrin β1. Combined with the advantages of lvSEM, this multiple-labelling method is a new method for studying the interactions between specific, functional molecules.
The application of TiO2-based devices is mainly dependent on their crystalline structure,morphology,size,and exposed facets.Two kinds of TiO2 with different structures,namely TiO2 pompons and TiO2 nanotubes,have been prepared by the hydrothermal method.TiO2 with different structures is characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),and Brunauer-Emmett-Teller(BET) surface area analysis.Solar cells based on poly(3-hexylthiophene)(P3HT) and TiO2 with different structures are fabricated.In the device ITO/TiO2/P3HT/Au,the P3HT is designed to act as the electron donor,and TiO2 pompons and TiO2 nanotubes act as the electron acceptor.The effects of the TiO2 structure on the performance of hybrid heterojunction solar cells are investigated.The device with TiO2 pompons has an open circuit voltage(Voc) of 0.51 V,a short circuit current(Jsc) of 0.21 mA/cm2,and a fill factor(FF) of 28.3%.Another device with TiO2 nanotubes has a V oc of 0.5 V,J sc of 0.27mA/cm2,and FF of 28.4%.The results indicate that the TiO2 nanotubes with a unidimensional structure have better carrier transport and light absorption properties than TiO 2 pompons.Consequently,the solar cell based on TiO2 nanotubes has a better performance.
Pt and its based alloy nanoparticles(NPs)have been reported to demonstrate novel enzyme-like activities.Varying composition is very important to realize the optimization of their functions through the tuning of electronic structure.In this paper,our effort is focused in this direction by tailoring the electronic structure of Pt NPs via alloying with copper.Using gold nanorod(Au NR)as core,a simple method to prepare PtCu alloy shell is developed(termed as Au@PtCu NR).The introduction of copper could result in endcap-preferred growth mode owing to the lattice mismatch between alloy shell and the Au core.The variation in the electronic structure changes the substrate affinity,and enhanced affinity was found for H2O2.Besides,the designed Au@PtCu nanostructures have realized spatial separation of catalytic and recognition sites.Binding of recognition antibodies had negligible effect on their catalytic activity.Based on their peroxidaselike activity,a highly sensitive detection of human immunoglobulin G(IgG)was demonstrated in a direct enzyme-linked immunosorbent assay(ELISA)mode.The detection limit can be as low as 90 pg/mL.
Natural enzymes as biological catalysts possess remarkable advantages,especially their highly efficient and selective catalysis under mild conditions.However,most natural enzymes are proteins,thus exhibiting an inherent low durability to harsh reaction conditions.Artificial enzyme mimetics have been pursued extensively to avoid this drawback.Quite recently,some inorganic nanoparticles(NPs) have been found to exhibit unique enzyme mimetics.In addition,their much higher stability overcomes the inherent disadvantage of natural enzymes.Furthermore,easy mass-production and low cost endow them more benefits.As a new member of artificial enzyme mimetics,they have received intense attention.In this review article,major progress in this field is summarized and future perspectives are highlighted.
