Spatially confined CuFe2O4 nanosphere in N/O-codoped porous carbon mimetics for triple-mode sensing of antibiotics and visual detection of neurotransmitters in biofluids.

BACKGROUND: Carbon-based nanozymes have recently received enormous concern, however, there is still a huge challenge for inexpensive and large-scale synthesis of magnetic carbon-based "Two-in-One" mimics with both peroxidase (POD)-like and laccase-like activities, especially their potential applications in multi-mode sensing of antibiotics and neurotransmitters in biofluids. Although some progresses have been made in this field, the feasibility of biomass-derived carbon materials with both POD-like and laccase-like activities by polyatomic doping strategy is still unclear. In addition, multi-mode sensing platform can provide a more reliable result because of the self-validation, self-correction and mutual agreement. Nevertheless, the use of magnetic carbon-based nanozyme sensors for the multi-mode detection of antibiotics and neurotransmitters have not been investigated. RESULTS: We herein report a shrimp shell-derived N, O-codoped porous carbon confined magnetic CuFe2O4 nanosphere with outstanding laccase-like and POD-like activities for triple-mode sensing of antibiotic d-penicillamine (D-PA) and chloramphenicol (CPL), as well as colorimetric detection of neurotransmitters in biofluids. The magnetic CuFe2O4/N, O-codoped porous carbon (MCNPC) armored mimetics was successfully fabricated using a combined in-situ coordination and high-temperature crystallization method. The synthesized MCNPC composite with superior POD-like activity can be used for colorimetric/temperature/smartphone-based triple-mode detection of D-PA and CPL in goat serum. Importantly, the MCNPC nanozyme can also be used for colorimetric analysis of dopamine and epinephrine in human urine. SIGNIFICANCE: This work not only offered a novel strategy to large-scale, cheap synthesize magnetic carbon-based "Two-in-One" armored mimetics, but also established the highly sensitive and selective platforms for triple-mode monitoring D-PA and CPL, as well as colorimetric analysis of neurotransmitters in biofluids without any tanglesome sample pretreatment.

Biotemplated fabrication of N/O co-doped porous carbon confined spinel NiFe2O4 heterostructured mimetics for triple-mode sensing of antioxidants and ameliorating packaging properties.

In this work, shrimp shell-derived magnetic NiFe2O4/N, O co-doped porous carbon nanozyme with superior oxidase (OXD)-like activity was prepared and used for colorimetric/photothermal/smartphone dual-signal triple-mode detection of antioxidants in fruits and beverages. The magnetic NiFe2O4/N, O co-doped porous carbon (MNPC) material was triumphantly fabricated using a combined in-situ surface chelation and pyrolysis method. The resultant MNPC composite exhibits a superior OXD-like activity, which can effectively oxidize 3,3',5,5'-tetramethylbenzidine (TMB) for yielding colorimetric/temperature dual-signal (CTDS) in absence of H2O2. This CTDS output sensor was successfully used for the determination of ascorbic acid and tannic acid. The proposed CTDS sensor with good specificity and high sensitivity can satisfy different on-site analysis requirements. Interestingly, the MNPC as a sustainable filler was further used for improving packaging properties of polyvinyl alcohol film. In short, this work offers a large-scale and cheap method to fabricate magnetic carbon-based nanozyme for monitoring antioxidants and ameliorating packaging properties.