While breakthroughs in peroxidase-like nanozymes for bioanalysis have been made, most of current nanozyme biosensing systems are based on a single signal output. Such sensing systems could be easily influenced by environmental and personal factors. We envision that nanozyme sensing systems with ratiometric signal outputs would provide more reliable and robust sensing performance. Herein, to construct such ratiometric sensing systems, three fluorescent graphitic carbon nitride (C 3 N 4 )-based nanozymes (i.e., C 3 N 4 −Ru, C 3 N 4 −Cu, and C 3 N 4 −hemin) with excellent peroxidase-like activities were prepared. These fluorescent nanozymes emitted a fluorescence at 438 nm when excited at 385 nm. Interestingly, when o-phenylenediamine (OPD) was catalytically oxidized to oxidized OPD (OPDox) in the presence of H 2 O 2 and nanozymes, the OPDox not only emitted an emerging fluorescence at 564 nm but also quenched the fluorescence at 438 nm of the nanozymes. We therefore employed the ratio of the fluorescent intensity at 564 and 438 nm (i.e., F 564 /F 438 ) as the signal output to construct the ratiometric biosensing systems. First, we used the C 3 N 4 −Ru nanozyme to construct the ratiometric H 2 O 2 sensing system, which showed not only the enhanced robustness but also wider linear range and better sensitivity than most reported H 2 O 2 sensors based on nanozymes. Second, with the assistance of glucose oxidase, glucose can be detected by such ratiometric sensing systems. Third, we used three different C 3 N 4 -based nanozymes to construct ratiometric sensor arrays for the detection and discrimination of five phosphates. This study provides new insights for constructing robust nanozyme biosensing systems.

Fusion of extracellular vesicles to cells contributes to many critical biological pathways. Inspired by the natural fusion process, Hang Xing and co‐workers developed a liposome fusion‐based transport strategy, termed LiFT, that enables the incorporation of a variety of functional moieties onto both external and internal cell membrane surfaces with precise orientation control (e202111647). By using LiFT, asymmetric DNA modifications with orthogonal functionalities on each side of the cell membrane were achieved, realizing applications such as heterotypic cell assembly and intracellular metabolite detection.

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By crosslinking protein spherical nucleic acid (SNA) into a supramolecular architecture X-SNA, the intracellular enzyme delivery efficiency was significantly enhanced, showing 3–4 times higher signal-to-noise ratio in detecting intracellular lactate.

Engineering of the cell plasma membrane using functional DNA is important for studying and controlling cellular behaviors. However, most efforts to apply artificial DNA interactions on cells are limited to external membrane surface due to the lack of suitable synthetic tools to engineer the intracellular side, which impedes many applications in cell biology. Inspired by the natural extracellular vesicle‐cell fusion process, we have developed a fusogenic spherical nucleic acid construct to realize robust DNA functionalization on both external and internal cell surfaces via liposome fusion‐based transport (LiFT) strategy, which enables applications including the construction of heterotypic cell assembly for programmed signaling pathway and detection of intracellular metabolites. This approach can engineer cell membranes in a highly efficient and spatially controlled manner, allowing one to build anisotropic membrane structures with two orthogonal DNA functionalities.