Bacillus cereus is increasingly recognized as one of the major causes of food poisoning in the industrialized world. In this paper, we describe a sensitive double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) that was developed for rapid detection of B. cereus in food to minimize the risk of contamination. The polyclonal antibody (pAb) and monoclonal antibodies (mAbs) specific to B. cereus were generated from rabbit antiserum and mouse ascites, respectively, using the octanoic acid/saturated ammonium sulfate precipitation method and protein A-sepharose columns. IgG-isotype mAbs were specially developed to undergo a novel peripheral multiple sites immunization for rapid gain of hybridomas and a subtractive screen was used to eliminate cross reactivity with closely related species such as Bacillus thuringiensis, B. subtilis, B. licheniformis and B. perfringens. The linear detection range of the method was approximately 1 × 104–2.8 × 106 cells/mL with a detection limit (LOD) of 0.9 × 103 cells/mL. The assay was able to detect B. cereus when the samples were prepared in meat with various pathogens. The newly developed analytical method provides a rapid method to sensitively detect B. cereus in food specimens.

Conventional lateral flow biosensing technologies face the dual formidable challenges of poor sensitivity and cumbersome quantitative devices. Here, we developed a Au@Pd nanopopcorn and aptamer nanoflower assisted lateral flow strip (ANAN-LFS) with a thermal signal output to improve detection sensitivity. Moreover, a smartphone-based thermal reader was designed and meticulously optimized to hand-held style, realizing the essential portability of this quantitative device. Experimental studies revealed that the synthesized Au@Pd nanopopcorns clearly red-shifted into the near-infrared region, thus resulting in a higher photothermal response than the standard gold nanoparticles. Aptamer nanoflowers enhanced the system’s biorecognition ability significantly compared with single-stranded aptamers due to their functional spatial structure, thus resulting in an even greater improvement in the sensitivity of the ANAN-LFS. With exosomes as model targets, the limit of detection (LOD) was calculated to be 1.4 × 104 exosomes/μL, which exhibited a 71-fold improved analytical performance. The feasibility of this system for detecting spiked biological samples at clinical concentrations was also confirmed. These results suggest that the proposed strategy of integrating a ANAN-LFS with a smartphone-based thermal reader has great potential as a powerful tool for bioanalytical applications, offering the combined unique advantages of high sensitivity and expedient portability.

Nucleic acid-based hydrogels that integrate intrinsic biological properties of nucleic acids and mechanical behavior of their advanced assemblies are appealing bioanalysis and biomedical studies for the development of new-generation smart biomaterials. It is inseparable from development and incorporation of novel structural and functional units. This review highlights different functional units of nucleic acids, polymers, and novel nanomaterials in the order of structures, properties, and functions, and their assembly strategies for the fabrication of nucleic acid-based hydrogels. Also, recent advances in the design of multifunctional and stimuli-responsive nucleic acid-based hydrogels in bioanalysis and biomedical science are discussed, focusing on the applications of customized hydrogels for emerging directions, including 3D cell cultivation and 3D bioprinting. Finally, the key challenge and future perspectives are outlined.

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Aims:  Ethidium monoazide in combination with quantitative PCR (EMA–qPCR) has been considered as a promising method to enumerate viable cells; however, its efficacy can be significantly affected by disinfection conditions and various environments. In this study, thermal disinfection, osmotic pressure and acids with different pH values were systematically investigated to achieve the optimum conditions. Methods and Results:  EMA treatment of pure cultures at low concentration (10 μg ml−1) for 20 min resulted in effective differentiation between viable and nonviable bacteria and had no effect on viable cells. Heating at 85°C for 35 min was the optimum condition that yields inactivated Escherichia coli (E. coli) cells that were not detected with EMA–qPCR. Performing EMA treatment in high‐salt ion environment (sodium chloride concentration ≥4%) could weaken EMA inhibition effect. Both strong and weak acid solutions could react with EMA, change its absorption spectra and influence EMA inhibition effect. Because of the sublethal acidification injury, underestimation of cell counts were found using EMA–qPCR method, and 40‐min incubation in Luria–Bertani medium could completely offset this error. Conclusion:  Our results provided optimum EMA treatment, thermal disinfection and environment conditions for EMA–qPCR and demonstrated the feasibility of this method when enumerating viable cells under varied osmotic pressure and pH environment. Significance and Impact of the Study:  Optimum EMA treatment, thermal disinfection and EMA‐treated environment will be successfully applied in EMA–qPCR. Osmotic pressure and acid‐induced injury can be detected by EMA–qPCR with optimization.