Single-atom catalysts (SACs) are promising candidates to catalyze electrochemical CO2 reduction (ECR) due to maximized atomic utilization. However, products are usually limited to CO instead of hydrocarbons or oxygenates due to unfavorable high energy barrier for further electron transfer on synthesized single atom catalytic sites. Here we report a novel partial-carbonization strategy to modify the electronic structures of center atoms on SACs for lowering the overall endothermic energy of key intermediates. A carbon-dots-based SAC margined with unique CuN2O2 sites was synthesized for the first time. The introduction of oxygen ligands brings remarkably high Faradaic efficiency (78%) and selectivity (99% of ECR products) for electrochemical converting CO2 to CH4 with current density of 40 mA·cm-2 in aqueous electrolytes, surpassing most reported SACs which stop at two-electron reduction. Theoretical calculations further revealed that the high selectivity and activity on CuN2O2 active sites are due to the proper elevated CH4 and H2 energy barrier and fine-tuned electronic structure of Cu active sites.

The design of an ideal drug delivery system with targeted recognition and zero premature release, especially controlled and specific release that is triggered by an exclusive endogenous stimulus, is a great challenge. A traceable and aptamer-targeted drug nanocarrier has now been developed; the nanocarrier was obtained by capping mesoporous silica-coated quantum dots with a programmable DNA hybrid, and the drug release was controlled by microRNA. Once the nanocarriers had been delivered into HeLa cells by aptamer-mediated recognition and endocytosis, the overexpressed endogenous miR-21 served as an exclusive key to unlock the nanocarriers by competitive hybridization with the DNA hybrid, which led to a sustained lethality of the HeLa cells. If microRNA that is exclusively expressed in specific pathological cell was screened, a combination of chemotherapy and gene therapy should pave the way for a targeted and personalized treatment of human diseases.

In chemotherapy, it is a great challenge to recruit endogenous stimuli instead of external intervention for targeted delivery and controlled release; microRNAs are the most promising candidates due to their vital role during tumorigenesis and significant expression difference. Herein, to amplify the low abundant microRNAs in live cells, we designed a stimuli-responsive DNA Y-motif for codelivery of siRNA and Dox, in which the cargo release was achieved via enzyme-free cascade amplification with endogenous microRNA as trigger and ATP (or H(+)) as fuel through toehold-mediated strand displacement. Furthermore, to realize controlled release in tumor cells, smart nanocarriers were constructed with stimuli-responsive Y-motifs, gold nanorods, and temperature-sensitive polymers, whose surfaces could be reversibly switched between PEG and RGD states via photothermal conversion. The PEG corona kept the nanocarriers stealth during blood circulation to protect the Y-motifs against nuclease digestion and enhance passive accumulation, whereas the exposed RGD shell under near-infrared (NIR) irradiation at tumor sites facilitated the specific receptor-mediated endocytosis by tumor cells. Through modulating NIR laser, microRNA, or ATP expressions, the therapy efficacies to five different cell lines were finely controlled, presenting NIR-guided accumulation, massive release, efficient gene silence, and severe apoptosis in HeLa cells; in vivo study showed that a low dosage of nanocarriers synergistically inhibited the tumor growth by silencing gene expression and inducing cell apoptosis under mild NIR irradiation, though they only brought minimum damage to normal organs. The combination of nanomaterials, polymers, and DNA nanomachines provided a promising tool for designing smart nanodevices for disease therapy.

A new and convenient sonoelectrochemical method was used to synthesize uniform three-dimensional (3D) dendritic Pt nanostructures (DPNs) at room temperature. The size and morphology of the final product could be controlled via simply adjusting the experiment parameters. The morphology and structure of the DPNs were characterized by transmission electron microscopy, high resolution transmission electron microscopy, field emission scanning electron microscopy, energy-dispersive X-ray, and X-ray diffraction. The formation process of the DPNs was carefully studied, and a spontaneous assembly mechanism was proposed based on the experimental results. Additionally, the electrocatalytic activity of the DPNs was evaluated using methanol and glucose as model molecules. The DPNs showed improved electrocatalytic activity toward methanol oxidation with respect to the monodisperse Pt nanoparticles; this improvement is due to the porosity structure and the greatly enhanced effective surface area. In addition, a sensitive enzyme-free biosensor can be easily developed for the detection of glucose in pH 7.4 phosphate buffer solution. The present method provides a new and simple strategy toward the fabrication of 3D DPNs with extensive applications.

MicroRNAs (miRNAs), as key regulators in gene expression networks, have participated in many biological processes, including cancer initiation, progression, and metastasis, indicative of potential diagnostic biomarkers and therapeutic targets. To tackle the low abundance of miRNAs in a single cell, we have developed programmable nanodevices with MNAzymes to realize stringent recognition and in situ amplification of intracellular miRNAs for multiplexed detection and controlled drug release. As a proof of concept, miR-21 and miR-145, respectively up- and down-expressed in most tumor tissues, were selected as endogenous cancer indicators and therapy triggers to test the efficacy of the photothermal nanodevices. The sequence programmability and specificity of MNAzyme motifs enabled the fluorescent turn-on probes not only to sensitively profile the distributions of miR-21/miR-145 in cell lysates of HeLa, HL-60, and NIH 3T3 (9632/0, 14147/0, 2047/421 copies per cell, respectively) but also to visualize trace amounts of miRNAs in a single cell, allowing logic operation for graded cancer risk assessment and dynamic monitoring of therapy response by confocal microscopy and flow cytometry. Furthermore, through general molecular design, the MNAzyme motifs could serve as three-dimensional gatekeepers to lock the doxorubicin inside the nanocarriers. The drug nanocarriers were exclusively internalized into the target tumor cells via aptamer-guided recognition and reopened by the endogenous miRNAs, where the drug release rates could be spatial-temporally controlled by the modulation of miRNA expression. Integrated with miRNA profiling techniques, the designed nanodevices can provide general strategy for disease diagnosis, prognosis, and combination treatment with chemotherapy and gene therapy.

Gas-phase N-doped graphene (gNG) was synthesized by a modified thermal annealing method using gaseous melamine as nitrogen source and then for the first time applied as a matrix in negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for small molecule analysis. Unlike the complicated adducts produced in positive ion mode, MS spectra obtained on gNG matrix in negative ion mode was only featured by deprotonated molecule ion peaks without matrix interference. By the gNG assisted desorption/ionization (D/I) process, some applications were carried out on a wide range of low-molecular weight (MW) analytes including amino acids, fatty acids, peptides, anabolic androgenic steroids as well as anticancer drugs, with an extraordinary laser desorption/ionization (LDI) efficiency over traditional α-cyano-4-hydroxycinnamic acid (CHCA) and other carbon-based materials in the negative ion detection mode. By comparison of a series of graphene-based matrixes, two main factors of matrix gNG were unveiled to play a decisive role in assisting negative ion D/I process: a well-ordered π-conjugated system for laser absorption and energy transfer; pyridinic-doped nitrogen species functioning as deprotonation sites for proton capture on negative ionization. The good salt tolerance and high sensitivity allowed further therapeutic monitoring of anticancer drug nilotinib in the spiked human serum, a real case of biology. Signal response was definitely obtained between 1 mM and 1 μM, meeting the demand of assessing drug level in the patient serum. This work creates a new application branch for nitrogen-doped graphene and provides an alternative solution for small molecule analysis.

This article describes a multimodified core-shell gold@silver nanoprobe for real-time monitoring the entire autophagy process at single-cell level. Autophagy is vital for understanding the mechanisms of human pathologies, developing novel drugs, and exploring approaches for autophagy controlling. A major challenge for autophagy study lies in real-time monitoring. One solution might come from real-time detection of in situ superoxide radicals (O2(•-)), because it is the main regulator of autophagy. In this work, our proposed nanoprobes were etched by O2(•-) and gave a notable wavelength change in the plasmon resonance scattering spectra. Both the experimental and simulated results suggested the wavelength change rate correlated well with O2(•-) level. This response enabled its application in real-time in situ quantification of O2(•-) during autophagy course. More importantly, with the introduction of "relay probe" operation, two types of O2(•-)-regulating autophagy processes were successfully traced from the beginning to the end, and the possible mechanism was also proposed.

The design of an ideal drug delivery system with targeted recognition and zero premature release, especially controlled and specific release that is triggered by an exclusive endogenous stimulus, is a great challenge. A traceable and aptamer-targeted drug nanocarrier has now been developed; the nanocarrier was obtained by capping mesoporous silicacoated quantum dots with a programmable DNA hybrid, and the drug release was controlled by microRNA. Once the nanocarriers had been delivered into HeLa cells by aptamermediated recognition and endocytosis, the overexpressed endogenous miR-21 served as an exclusive key to unlock the nanocarriers by competitive hybridization with the DNA hybrid, which led to a sustained lethality of the HeLa cells. If microRNA that is exclusively expressed in specific pathological cell was screened, a combination of chemotherapy and gene therapy should pave the way for a targeted and personalized treatment of human diseases.