Quantum dots (QDs) are nanoparticles with size-dependent optical and electronic properties that have been proposed for various applications, such as energy-efficient displays and lighting, photovoltaic devices, and biological markers. [1][2][3][4][5][6] Compared with other fluorescent (FL) materials (conventional dyes, polymers, or propeins), QDs offer many promising advantages, such as bright fluorescence, high photostability, and resistance to metabolic degradation in bioapplications. [7][8][9] However, most high-performance QDs are limited by toxicity from their metal elements, such as cadmium. [10,11] Extensive efforts have thus been made on the development of non-or low-toxic FL nanomaterials as alternatives to the semiconductor-based QDs. Carbon-based dots (CDs), including carbon nanoparticles of less than 10 nm in size, [12] which are known as carbon quantum dots (CQDs) and graphene nanosheets of less than 100 nm in size, [13] which are known as graphene quantum dots (GQDs), are particularly encouraging owing to their outstanding optical properties, low toxicity, good biocompatibility, and robust chemical inertness. [6,12] Various methods have been demonstrated in preparation of FL CDs, such as electrochemical oxidation processes, [14,15] chemical oxidation methods, [6,12,[16][17][18] hydrothermal cutting strategies, [19,20] and carbonizing organics routes. [21][22][23][24] Nevertheless, most of the developed methods are unsatisfactory owing to expensive equipment required, low yields, or complicated procedures. In particular, most obtained CDs have a relatively low FL quantum yield (FLQY, usually less than 50 %) in comparison to the conventional semiconductor QDs. Most recently, doped CDs were proposed for highly FL dots. [25][26][27] For example, ZnS-doped CDs with the passivation of oligomeric poly(ethylenelycol) diamine (PEG1500N) molecules show a 78 % FLQY after a gel column fractionation. [26] However, the preparation of highly FL ZnS-doped CDs is complicated. Moreover, the poor chemical inertness of the ZnS would be a severe limitation to broad applications of the CDs. Thus, there is a great need to develop a facile, low-cost, and high-yield method for the preparation of CDs with strong FL emission. Herein, citric acid (CA) and l-cysteine were used to produce nitrogen and sulfur co-doped CDs (N,S-CDs) through a one-step hydrothermal treatment. The CA serves as the carbon source, while the l-cysteine provides nitrogen and sulfur. Compared with other reported CDs, the as-prepared N,S-CDs exhibit very high FLQY (73 %) and excitationindependent emission, resulting from the synergy effect of the doped nitrogen and sulfur atoms.The obtained N,S-CD solution exhibits a long-term homogeneous phase without any noticeable precipitation at room temperature. The transmission electron microscopy (TEM) image (Figure 1 a,g) shows that the size of the asprepared N,S-CDs is distributed in the range from 5 to 9 nm, with an average size of 7 nm. High-resolution TEM (HRTEM) images (Figure 1 b) reveal the high crystallin...

Superoxide anion (O2−) is implicated in a wide variety of biological phenomena and oxidative stress‐related diseases. The electrochemical detection of O2− is very attractive but relies on superoxide dismutase enzymes, thus suffering from high cost and low durability. The advances of nanoscience allows architecting while functionalizing a biomimetic sensing platform in nanoscales for high sensitivity and specificity. In this work, manganous phosphate (Mn3(PO4)2) nanosheets, a biomimetic enzyme, are template‐synthesized with DNA and further assembled on carbon nanotubes (CNTs) to form unique DNA‐Mn3(PO4)2‐CNT nanocomposite sheets, of which the Mn3(PO4)2 sheets efficiently catalyze the dismutation of O2− while CNTs enable fast electron transfer, thus achieving highly sensitive and specific detection of O2− with long‐term stability. The biomimetic O2− sensor is further used to monitor O2−in situ released from mouse cancer cell and normal skin cell under drug stimulation, showing excellent real time quantitative detection capability. This work demonstrates a nanoscale approach to not only synthesize but also design a biomimetic enzyme for comparable performance with the natural enzyme‐based biosensor while rendering much higher durability than the natural one and thus holding a great promise for broad applications in fundamental research, clinic diagnostics and screening for drug therapy effects.

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Phototherapies such as photothermal therapy (PTT) and photodynamic therapy (PDT) are considered as alternatives for tumor remedies, because of their advantages of precise spatial orientation, minimally invasive, and nonradiative operation. However, most of phototherapeutic agents still suffer from low photothermal conversion efficacy and photodynamic performance, poor biocompatibility, and intratumor accumulation. Herein a biocompatible and target-deliverable PTT-PDT self-synergetic nanoplatform of RGD-BPNS@SMFN based on temperature-dependent catalase (CAT)-like behavior for tumor elimination is presented. The homogeneously dispersible nanoplatform is designed and fabricated through anchoring spherical manganese ferrite nanoparticles (SMFN) to black phosphorus nanosheets (BPNS), followed by arginine-glycine-aspartic acid (RGD) peptide modification. The nanoplatform exhibits excellent targeting ability and enhanced photonic response in comparison to plain BPNS and SMFN in vitro and in vivo. It is found that PTT and PDT have a self-synergetic behavior by means of the dual phototherapy mode interaction. The self-synergetic mechanism is mainly ascribed to PTT-promoted inherent CAT-like activity in the nanoplatform, which remodels the tumor hypoxia microenvironment and further ameliorates the PDT efficiency, providing promising high performance nanoplatform for synergetic dual mode phototherapy, enriching the design for the antitumor nanozyme.

Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: http://dx.