Nanotechnology has become more and more potentially used in diagnosis or treatment of diseases. Advances in nanotechnology have led to new and improved nanomaterials in biomedical applications. Common nanomaterials applicable in biomedical applications include liposomes, polymeric micelles, graphene, carbon nanotubes, quantum dots, ferroferric oxide nanoparticles, gold nanoparticles (Au NPs), and so on. Among them, Au NPs have been considered as the most interesting nanomaterial because of its unique optical, electronic, sensing and biochemical properties. Au NPs have been potentially applied for medical imaging, drug delivery, and tumor therapy in the early detection, diagnosis, and treatment of diseases. This review focuses on some recent advances in the use of Au NPs as drug carriers for the intracellular delivery of therapeutics and as molecular nanoprobes for the detection and monitoring of target molecules.

Chemical modification with foreign atoms is a leading strategy to intrinsically modify the properties of host materials. Among them, potassium (K) modification plays a critical role in adjusting the electronic properties of carbon materials. Graphene, a true 2D carbon material, has shown fascinating applications in electrochemical sensing and biosensing. In this work, a facile and mild strategy to K‐modifying in graphene at room‐temperature is reported for the first time. X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectra, and cyclic voltammetry are used to characterize this K‐modified graphene. The K‐modified graphene is capable of acting as an electron transfer medium and more efficiently promotes charge transfer than unmodified graphene. A highly sensitive and stable amperometric sensor based on its excellent electrocatalytic activity toward the oxidation of NO2− is proposed. The sensor shows a linear range from 0.5 μM to 7.8 mM with a detection limit of 0.2 μM at a signal‐to‐noise ratio of 3. The modified electrode has excellent analytical performance and can be successfully applied in the determination of NO2− released from liver cancer and leukemia cells and shows good application potential in biological systems.

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Electrochemical reduction of carbon dioxide (CO 2 ) to formate is energetically inefficient because a high overpotential (>1.0 V) is required for most traditional catalysts. In this work, Bi 2 O 2 CO 3 (BOC) nanosheets were synthesized as electrocatalysts of CO 2 reduction for the first time. Additionally, BOC decorated on the glassy carbon electrode was reduced in situ to metal Bi (RB) for comparing the catalytic performance toward CO 2 reduction to that of BOC. The maximum faradaic efficiency of BOC was 83% at an overpotential of 0.59 V, which is a little lower than that of RB (90% obtained at the overpotential of 0.99 V). However, the overpotential for the reduction of CO 2 to formate on BOC is obviously decreased compared to that on RB. After 27 h of electrolysis, approximately 80% formate selectivity was obtained using the BOC catalyst. According to the experimental results and the related literature, a new mechanism for the CO 2 reduction reaction on BOC was proposed, which may play a guiding role in future catalyst design.

A branched electrode platform was proposed for label-free and reagentless simultaneous tumor markers detection based on different redox substrates.