Fluorescent/phosphorescent dual-emissive conjugated polymer dots were designed and synthesized, ere used for tumor hypoxia sensing via ratiometric imaging and photoluminescence lifetime imaging.

Low-price, high-performance and strong-stability electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are highly significant in the application of clean energy devices like rechargeable zinc-air batteries and renewable fuel cells. In this paper, a Prussian blue analogue Co3­[Fe­(CN)6]2·nH2O (Co-Fe PBA), as a well-known member of the metal–organic framework family, was electrospun into polyacrylonitrile (PAN) nanofibers to obtain composite Co-Fe PBA@­PAN nanofibers. Nitrogen-doped carbon nanofibers encapsulated FeCo alloy nanoparticles (FeCo-NCNFs-Ts, T = 700, 800, 900 °C) were synthesized by pyrolysizing Co-Fe PBA@­PAN precursor at different temperatures under an argon atmosphere. The effects of different calcination temperatures and mass ratios between Co-Fe PBA and PAN on ORR/OER catalytic activity were explored. Among FeCo-NCNFs-Ts, FeCo-NCNFs-800 had the highest bifunctional electrocatalytic performance with a lower reversible overvoltage of 0.869 V between ORR (E 1/2) and OER (E j = 10 mA cm–2), excellent stability and methanol durability, which even exceeded those of Pt/C and RuO2. The superb bifunctional activity for FeCo-NCNFs-800 was comparable to that of non-noble electrocatalysts reported in recent literatures. Moreover, the zinc-air battery based on the FeCo-NCNFs-800 air-cathode catalyst had a high power density of 74 mW cm–2 and strong cycling stability (125 cycles for 42 h), which can be comparable to a Pt/C-RuO2 zinc-air battery. The impressive bifunctional activity on ORR and OER for the FeCo-NCNFs-800 catalyst in the zinc-air battery can be attributed to the synergistic effects of the one-dimensional fibrous structure, FeCo alloy nanoparticles, Co-N (pyridinic-N) active sites, and numerous mesopores.

Molecular oxygen (O2) plays a key role in many physiological processes, and becomes a toxicant to kill cells when excited to 1O2. Intracellular O2 levels, or the degree of hypoxia, are always viewed as an indicator of cancers. Due to the highly efficient cancer therapy ability and low side effect, photodynamic therapy (PDT) becomes one of the most promising treatments for cancers. Herein, an early‐stage diagnosis and therapy system is reported based on the phosphorescent conjugated polymer dots (Pdots) containing Pt(II) porphyrin as an oxygen‐responsive phosphorescent group and 1O2 photosensitizer. Intracellular hypoxia detection has been investigated. Results show that cells treated with Pdots display longer lifetimes under hypoxic conditions, and time‐resolved luminescence images exhibit a higher signal‐to‐noise ratio after gating off the short‐lived background fluorescence. Quantification of O2 is realized by the ratiometric emission intensity of phosphorescence/fluorescence and the lifetime of phosphorescence. Additionally, the PDT efficiency of Pdots is estimated by flow cytometry, MTT cell viability assay, and in situ imaging of PDT induced cell death. Interestingly, Pdots exhibit a high PDT efficiency and would be promising in clinical applications.