Hao Shen,Xuelian Zheng,Zixin Zhou,Wenting He,Mengqi Li,Ping Su,Jiayi Song,Yi Yang
Various organelles (e.g., mitochondria and chloroplasts) have a multicompartment structure, providing superior function of material transformation, selective segregation and energy conversion. Enlightened by the elegant evolution of nature, intended isolation of the biochemical process by cooperative multicompartments in cells has become an appealing blueprint to construct bioreactors. In this study, we develop a “soft separation” way to establish a delicate multicompartment multienzyme system (MMS) with polyphenol-encapsulated enzyme–DNA conjugates, which are anchored on magnetic Janus particles, providing a biomimetic catalysis network with the model cascade reactions in confinement. The well-designed MMS exhibits preferable bioactivity benefitting from the dependable DNA bridges and the oriented immobilization of enzymes, while the polyphenol shell further protects the anchored enzymes from exterior attacks, such as heat and enzymatic degradation. Moreover, by applying the MMS as nanomotors, the asymmetrical distribution of enzymes on Janus particles is found to improve mutual elevation between the self-driven locomotion and enzyme-mediated reactions, delivering enhanced dispersal ability and bioactivity. Owing to the excellent enzymatic activity, promoted stability and satisfying biocompatibility, the assembled MMS is proved to be promising for the in vitro and intracellular sensing of glucose, showing significant potential for biochemical analysis applications.
Tb 3+ -doped carbon dots (Tb 3+ @CDs) were prepared in a facile hydrothermal method by using ammonium citrate as carbon source and Tb 3+ as dopant. A 15-bp GT-rich single-strand DNA (ssDNA) was introduced to sensitize Tb 3+ via the antenna effect for generating two fluorescence signals (CDs and Tb 3+ ), forming a conjugate of Tb 3+ @CDs/ssDNA. The ratiometric fluorescence of Tb 3+ @CDs/ssDNA could be reversibly regulated by Ag + and Cys, in which the fluorescence peak at 546 nm of Tb 3+ could be switched to “On” or “Off” as the signal indicator while the fluorescence peak at 444 nm of CDs remained constant as the build-in reference. The proposed Ag + /Cys-mediated reversible fluorescence changes in Tb 3+ @CDs/ssDNA was also proven for the design of a self-calibrating ratiometric fluorescence logic system. By integrated with the specific reaction between H 2 O 2 and Cys, Tb 3+ @CDs/ssDNA was applied for ratiometric fluorescence detection of H 2 O 2 . More importantly, the sensing strategy could be further successfully extended to the monitoring of H 2 O 2 -produced oxidase-related reactions, such as GOx-biocatalyzed oxidation of glucose (the limit of detection: 0.06 μM) and was well applied in rat serum compared to commercial kits. This work unveiled a novel ratiometric fluorescent design, which is cost-effective, simple to prepare and easy-to-use without chemical modification or fluorescence labeling .
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