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Quantum interference (QI) in single molecular junctions shows a promising perspective for realizing conceptual nanoelectronics. However, controlling and modulating the QI remains a big challenge. Herein, two-type substituents at different positions of meta-linked benzene, namely electron-donating methoxy (–OMe) and electron-withdrawing nitryl (–NO2), are designed and synthesized to investigate the substituent effects on QI. The calculated transmission coefficients T(E) indicates that –OMe and –NO2 could remove the antiresonance and destructive quantum interference (DQI)-induced transmission dips at position 2. –OMe could raise the antiresonance energy at position 4 while –NO2 groups removes the DQI features. For substituents at position 5, both of them are nonactive for tuning QI. The conductance measurements by scanning tunneling microscopy break junction show a good agreement with the theoretical prediction. More than two order of magnitude single-molecule conductance on/off ratio could be achieved at the different positions of –NO2 substituent groups at room temperature. The present work proves chemical substituents can be used for tuning QI features in single molecular junctions, which provides a feasible way toward realization of high-performance molecular devices.

It is important for a controlled release system to determine whether nanoparticles can penetrate cell membranes and deliver protein into the nuclear or cytosolic compartments of cells, and thus function as carriers. Here, we prepared different functionalized mesoporous magnetic hollow nanoparticles (MMHs) and chose bovine serum albumin (BSA) as a model protein to detect the intracellular trafficking of MMHs. The results showed that MMHs modified with amino groups (AMMHs) were efficient in protein loading and that the loading was dependent on the pH, temperature and ionic strength. Furthermore, we found that the AMMHs not only transported BSA into the cells but also released the BSA carried into the nuclear or cytosolic compartments of the cells. In addition, the nanoparticles were biocompatible, and the encapsulation of BSA in AMMHs did not affect their bioactivity. Taken together, AMMHs are excellent carriers for releasing protein into the cytosol and nucleus, and they have the potential to be used in a controlled release system.

A new glucose biosensor based on the electron transfer and photothermal effect of gold nanorods (GNRs) is reported here. The biosensor was prepared by immobilizing glucose oxidase (GOx) on a platinum (Pt) electrode by a composite film consisting of GNRs, polyvinyl butyral (PVB) and glutaraldehyde. GNRs were synthesized by a gold seed-mediated cetyltrimethylammonium bromide (CTAB) surfactant-assisted approach. The fabrication, characterization and analytical performance of the glucose biosensor based on GNRs are described in this paper. Moreover, the modulation of the biosensor by the photothermal effect based on the unique surface plasma resonance (SPR) property of GNRs was investigated for the first time. The results show that the current response of a glucose biosensor can significantly increase, induced by the electrical conductivity and photothermal effect of GNRs.

An innovative drug delivery system based on magnetic and fluorescent multifunctional chitosan nanoparticles was developed, which combined magnetic targeting, fluorescent imaging and stimulus-responsive drug release properties into one drug delivery system. Water-soluble superparamagnetic Fe3O4 nanoparticles, CdTe quantum dots (QDs) and pharmaceutical drugs were simultaneously incorporated into chitosan nanoparticles; cross-linking the composite particles with glutaraldehyde tailored their size, morphology, surface properties and drug release behaviors. The system showed superparamagnetic and strong fluorescent properties, and was used as a controlled drug release vehicle, which showed pH-sensitive drug release over a long time. The composite magnetic and fluorescent chitosan nanoparticles are potential candidates as a smart drug delivery system.