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Nanozymes are an excellent class of optical reporters for the development of sensitive biosensors for widespread applications. In this study, mesoporous core-shell palladium@platinum (Pd@Pt) nanoparticles were synthesized and then applied as signal amplifier in a dual lateral flow immunoassay (LFIA) and integrated with a smartphone-based device for use in simultaneous detection of Salmonella Enteritidis and Escherichia coli O157:H7. After optimization, the limit of detections were calculated to be ∼20 cfu/mL for S. Enteritidis and ∼34 cfu/mL for E. coli O157:H7, respectively. The greatly improved sensitivity was contributed by the peroxidase-like catalytic activity of the Pd@Pt nanoparticles for signal enhancement and the parallel design of dual detection for eliminating the cross-interference. The estimated recoveries of the dual LFIA range from 91.44 to 117.00%, which indicated that the developed method is capable of detecting live bacteria in food samples. This approach provides an attractive platform for S. Enteritidis and E. coli O157:H7 detection using a smartphone-based device as the sole piece of equipment, indicating great promise for foodborne pathogen analysis or in-field food safety tracking.

In this paper we demonstrate for the first time that structural nanocomposites providing dual drug release can be generated using a combination of electrospraying and electrospinning. Ketoprofen (KET) was used as a model drug, and polyvinylpyrrolidone (PVP) and Eudragit1 L100-55 (EL100) respectively taken as the sheath and core matrices to prepare the nanofibers. Scanning and transmission electron microscope observations demonstrated that the nanofibers had smooth surfaces and cross-sections, and distinct coresheath nanostructures. They also had relatively uniform diameters of 0.64 ¡ 0.21 mm. Differential scanning calorimetry and X-ray diffraction results indicated that the nanofibers contained KET homogeneously distributed in both the sheath and core parts of the fibers. IR spectra indicated that this molecular dispersion was likely to be a result of hydrogen bonding between the components. In vitro dissolution tests showed that the core-sheath fibers provided dual drug release profiles with an immediate release of 35.1% in acidic solutions and sustained release of 62.2% in a pH 6.8 phosphate buffer. The strategy developed here significantly expands the applications of electrohydrodynamic atomization processes in producing novel structural nanocomposites for complex and time-programmed drug release profiles.

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Nanocatalytic therapy, involving the nanozyme-triggered production of reactive oxygen species (ROS) in the tumor microenvironment (TME), has demonstrated potential in tumor therapy, but nanozymes still face challenges of activity and specificity that compromise the therapeutic efficacy. Herein, we report a strategy based on a single-atom nanozyme to initiate cascade enzymatic reactions in the TME for tumorspecific treatment. The cobalt-single-atom nanozyme, with CoÀ N coordination on N-doped porous carbon (Co-SAs@NC), displays catalase-like activity that decomposes cellular endogenous H 2 O 2 to produce O 2 , and subsequent oxidase-like activity that converts O 2 into cytotoxic superoxide radicals to efficiently kill tumor cells. By incorporation with doxorubicin, the therapy achieves a significantly enhanced antitumor effect in vivo. Our findings show that cascade TME-specific catalytic therapy combined with chemotherapy is a promising strategy for efficient tumor therapy.

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