Abstract：
A dual-recognition strategy is reported to construct a one-step washing and highly efficient signal-transduction tag system for high-sensitivity colorimetric detection of Staphylococcus aureus (S. aureus). The porous (gold core)@(platinum shell) nanozymes (Au@PtNEs) as the signal labels show highly efficient peroxidase mimetic activity and are robust. For the sake of simplicity the detection involved the use of a vancomycin-immobilized magnetic bead (MB) and aptamer-functionalized Au@PtNEs for dual-recognition detection in the presence of S. aureus. In addition, we designed a magnetic plate to fit the 96-well microplate to ensure consistent magnetic properties of each well, which can quickly remove unreacted Au@PtNEs and sample matrix while avoiding tedious washing steps. Subsequently, Au@PtNEs catalyze hydrogen peroxide (H2O2) to oxidize 3,3\',5,5\'-tetramethylbenzidine (TMB) generating a color signal. Finally, the developed Au@PtNEs-based dual-recognition washing-free colorimetric assay displayed a response in the range of S. aureus of 5 × 101-5 × 105 CFU/mL, and the detection limit was 40 CFU/mL within 1.5 h. In addition, S. aureus-fortified samples were analyzed to further evaluate the performance of the proposed method, which yielded average recoveries ranging from 93.66 to 112.44% and coefficients of variation (CVs) within the range 2.72-9.01%. These results furnish a novel horizon for the exploitation of a different mode of recognition and inexpensive enzyme-free assay platforms as an alternative to traditional enzyme-based immunoassays for the detection of other Gram-positive pathogenic bacteria.
摘要：
据报道，双重识别策略可构建一步洗涤和高效信号转导标签系统，用于高灵敏度比色检测金黄色葡萄球菌（S.金黄色葡萄球菌）。作为信号标记的多孔(金核)@(铂壳)纳米酶(Au@PtNE)显示出高效的过氧化物酶模拟活性并且是稳健的。为了简单起见,检测涉及使用万古霉素固定的磁珠(MB)和适体官能化的Au@PtNE用于在金黄色葡萄球菌存在下的双重识别检测。此外,我们设计了一个磁性板，以适应96孔微孔板，以确保每个孔的磁性一致，这可以快速去除未反应的Au@PtNE和样品基质，同时避免繁琐的洗涤步骤。随后，Au@PtNE催化过氧化氢（H2O2）氧化3,3'，5,5'-四甲基联苯胺(TMB)产生颜色信号。最后,开发的基于Au@PtNEs的双识别免洗涤比色测定显示在5×101-5×105CFU/mL的金黄色葡萄球菌范围内的响应，在1.5h内检测限为40CFU/mL。分析了金黄色葡萄球菌强化的样品，以进一步评估所提出方法的性能，平均回收率在93.66至112.44％之间，变异系数（CV）在2.72-9.01％之间。这些结果为开发不同的识别模式和廉价的无酶测定平台提供了新的视野，以替代传统的基于酶的免疫测定来检测其他革兰氏阳性病原菌。
