Early detection of ovarian cancer, the most lethal type of gynecologic cancer, can dramatically improve the efficacy of available treatment strategies. However, few screening tools exist for rapidly and effectively diagnosing ovarian cancer in early stages. Here, we present a facile “lock–key” strategy, based on rapid, specific detection of plasma lysophosphatidic acid (LPA, an early stage biomarker) with polydiacetylenes (PDAs)-based probe, for the early diagnosis of ovarian cancer. This strategy relies on specifically inserting LPA “key” into the PDAs “lock” through the synergistic electrostatic and hydrophobic interactions between them, leading to conformation transition of the PDA backbone with a concomitant blue-to-red color change. The detailed mechanism underlying the high selectivity of PDAs toward LPA is revealed by comprehensive theoretical calculation and experiments. Moreover, the level of LPA can be quantified in plasma samples from both mouse xenograft tumor models and patients with ovarian cancer. Impressively, this approach can be introduced into a portable point-of-care device to successfully distinguish the blood samples of patients with ovarian cancer from those of healthy people, with 100% accuracy. This work provides a valuable portable tool for early diagnosis of ovarian cancer and thus holds a great promise to dramatically improve the overall survival.

Magnetic adsorbents have recently been extensively investigated and applied in the field of water purification, because of their magnetic characters which are advantageous for the separation and recycle of these materials. Unfortunately, common magnetic materials are unstable and prone to dissolution in acid environment, thus limiting their practical applications in wide pH range, particularly in acidic condition. Therefore, it is highly imperative to exploit a novel magnetic adsorbent that is acid-resistant, to simplify separation process during the water purification. In present work, an acid-resistant magnetic Co/C nanocomposite was synthesized by using ZIF-67 as both template and precursor. The ZIF-67 was carbonized in an argon atmosphere at 800 °C for 1 h, and then treated with acid. Upon calcination at an appropriate temperature in inert atmosphere, the generated Co nanoparticles were uniformly wrapped by graphite layers, due to the graphitization of carbon upon the catalysis effect of Co. The formed graphite layers were able to protect the Co particles from oxidation and acid environment, thus resulting in the generation of an acid-resistant magnetic adsorbent that can be applied in a wide pH range (pH 1–13). Remarkably, the as-synthesized magnetic Co/C nanocomposite demonstrated excellent adsorption performance towards two typical organic dyes (rhodamine B and malachite green) over a wide pH range. The adsorption isotherms of rhodamine B and malachite green on Co/C nanocomposite were well fitted with the Langmuir model. Impressively, the maximum adsorption capacities towards rhodamine B and malachite green were estimated to be 400.0 and 561.8 mg g−1, respectively, far exceeding many previously reported adsorbents. Moreover, the adsorbent could be easily regenerated by washing with ethylene glycol (EG), suggesting its excellent reusability. Even after 5 cycles of reuse, no obvious capacity degradation was observed. Furthermore, practical application of the magnetic adsorbent was demonstrated by the removal of organic dyes from domestic wastewater with a superior removal efficiency of higher than 97%.An acid-resistant magnetic Co/C nanocomposites was synthesized by using ZIF-67 as both template and precursor. The acid-resistant magnetic nanocomposites demonstrated excellent adsorption performance for rhodamine B and malachite green over a wide pH range. Moreover, the adsorbent capacity could be easily regenerated by washing with ethylene glycol (EG), suggesting its excellent reusability.

To alleviate the kinetic barriers associated with ORR (oxygen reduction reaction) and OER (oxygen evolution reaction) in electrochemical systems, efficient nonprecious electrocatalysts are urgently required. Here we report a facile soft-template mediated approach for fabrication of nanostructured cobalt–iron double sulfides that are covalently entrapped in nitrogen-doped mesoporous graphitic carbon (Co0.5Fe0.5S@N-MC). Notably, with a positive half-wave potential (0.808 V) and a high diffusion-limiting current density, the composite material delivers unprecedentedly striking ORR electrocatalytic activity among recently reported nonprecious late transition metal chalcogenide materials in alkaline medium. Various characterization techniques, including X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, are conducted to elucidate the correlation between structural features and catalytic activities of the composite. Moderate substitution and well-dispersion of iron in bimetallic sulfide composites are believed to have positive effect on the adsorption and activation of oxygen-containing species, thus leading to conspicuous ORR and OER catalytic enhancement compared to their monometallic counterparts. Besides, the covalent bridge between active sulfide particles and mesoporous carbon shells provides facile pathways for electron and mass transport. Beneficially, the intimate coupling interaction renders prolonged electrocatalytic performances to the composite. Our results may possibly lend a new impetus to the rational design of bi- or multimetallic sulfides encapsulated in porous carbon with improved performance for electrocatalysis and energy storage applications.Keywords: electrocatalysts; fuel cells; late transition metal chalcogenides; mesoporous carbon; oxygen evolution reaction; oxygen reduction reaction

•DNA metallization shed light on the coordination-driven self-assembly strategy.•Co–N/C maintained the structural uniformity and high-density Co–N active sites.•The alkaline direct methanol fuel cell generated high maximum power density.•The Co–N species in Co–N/C and the structure–activity correlation were demonstrated.Enhancing the catalytic activity of non-precious metal catalysts (NPMCs) for oxygen reduction reaction (ORR) requires determination of active centers and a better understanding of the structure–activity relationship. However, key technical challenges in controlling the structural uniformity of NPMCs and maximizing the number of exposed active sites make this goal hard to achieve. Here, inspired by the facile self-assembly strategy for DNA metallization, we have fabricated Co–adenine nanocomposite spheres (Co–A NSs) with uniform structures and well-recognized Co–N4 configuration. Direct pyrolysis of Co–A NSs leads to the formation of monodisperse rambutan-like Co–N/C composites with high porosity and degree of graphitization, as well as homogeneous and high-density Co–N active sites, which endow them with excellent ORR catalytic activity in both base and acid conditions. With Co–N/C as the cathode catalyst, the assembled alkaline direct methanol fuel cell (ADMFC) generates extremely high open-circuit voltage (0.80 V) and unprecedentedly high maximum output power density (40.1 mW cm−2), which is successfully utilized to illuminate a light-emitting diode (LED) lantern. Moreover, the easily controlled structure of Co–N/C catalysts enables us to further reveal their structure–activity relationship, which may provide guidance for future design of advanced electrocatalysts.