The early rapid and ultrasensitive detection of pathogenic bacteria is crucial for preventing foodborne illnesses and addressing bacterial infections effectively. Herein, we have developed an ultrasensitive and rapid method for detecting Salmonella typhimurium based on specific phage tail spike protein-magnetic separation, dual signal amplification by four-in-one AuPt nanoparticles coated enzyme-antibiotic-inorganic nanoflowers and smartphone-assisted paper sensor. The generation of nanoflowers involved the encapsulation of horseradish peroxidase (HRP) and polymyxin B (PMB) within inorganic nanocrystal composites in Ca^2 + solution, imitating the natural biomineralization process through nanoarchitectonics. Subsequently, the nanoenzyme AuPt nanoparticles were coupled to the nanoflower surface by electrostatic adsorption for enhanced catalytic activity. The prepared HRP-PMB-CaHPO₄@AuPt nanoflowers could both target gram-negative bacteria using the biorecognition unit (PMB) and alleviate enzymatic activity by dual signal amplification elements (HRP and AuPt). The phage tail spike protein-magnetic beads were utilized for specific separation of S. typhimurium. Following this, a paper-based sensor containing 3,3′,5,5′-tetramethyl benzidine (TMB) catalyzed by HRP and AuPt was introduced to induce a color change. Finally, a smartphone application (APP) was used to analyze the RGB (red-green-blue) values of the paper sensor, enabling the direct detection of S. typhimurium. The limit of detection (LOD) was 3.28 × 10¹ CFU/mL and the entire detection took 30 min, showing exceptional performance. This proposed assay, serving as a rapid and highly sensitive platform, successfully addresses the requirement for an efficient detection method for S. typhimurium, particularly in limited-resources settings.

中文翻译：

---

基于四合一AuPt纳米酶包被的酶-抗生素-无机纳米花双信号放大的快速超灵敏检测鼠伤寒沙门氏菌


病原菌的早期快速和超灵敏检测对于预防食源性疾病和有效解决细菌感染至关重要。在此，我们开发了一种基于特异性噬菌体尾部刺突蛋白-磁性分离的超灵敏快速检测鼠伤寒沙门氏菌的方法，通过四合一 AuPt 纳米颗粒包被的酶-抗生素-无机纳米花和智能手机辅助纸张传感器进行双重信号放大。纳米花的产生涉及将辣根过氧化物酶 （HRP） 和多粘菌素 B （PMB） 封装在 Ca^{2 +} 溶液中的无机纳米晶体复合材料中，通过纳米结构学模拟自然生物矿化过程。随后，纳米酶 AuPt 纳米颗粒通过静电吸附偶联到纳米花表面以增强催化活性。制备的 HRP-PMB-CaHPO₄@AuPt 纳米花既可以使用生物识别单元 （PMB） 靶向革兰氏阴性菌，也可以通过双信号放大元件 （HRP 和 AuPt） 减轻酶活性。噬菌体尾部刺突蛋白-磁珠用于鼠伤寒沙门氏菌的特异性分离。在此之后，引入含有 HRP 和 AuPt 催化的含有 3,3'，5,5'-四甲基联苯胺 （TMB） 的纸基传感器以诱导颜色变化。最后，使用智能手机应用程序 （APP） 分析纸张传感器的 RGB （红-绿-蓝） 值，从而能够直接检测鼠伤寒沙门氏菌。检测限 （LOD） 为 3.28 × 10¹ CFU/mL，整个检测耗时 30 min，表现出优异的性能。 这种提出的检测方法作为一种快速且高度灵敏的平台，成功地满足了对鼠伤寒沙门氏菌有效检测方法的要求，特别是在资源有限的环境中。