AuNPs金属化是调控胶体金LSPR的一种新方法。该方法通常采用双氧水、抗坏血酸及对氨基苯酚等还原剂将银离子在AuNPs表面还原形成银包金的核壳纳米结构，产生LSPR及颜色变化。但以上还原剂稳定性差，导致在实践中应用受到限制。银离子在氨存在下可被葡萄糖醛基还原形成单质Ag，而葡萄糖具有更好的稳定性。申请人前期实验发现，改变氨或葡萄糖浓度可调控银离子在金纳米花（AuNFs）表面的还原速度，产生丰富的颜色变化。依据此特性，申请人首次提出以脲酶或蔗糖酶替代常规ELISA中辣根过氧化酶，实现对氨或葡萄糖的精细调控，以此建立基于AuNFs 金属化的pELISA新方法；在此基础上进一步提出以硅球聚丙烯酸分子刷为pELISA载酶“集装箱”，通过增大菌体表面酶载量实现E.coli O157:H7、LM以及Salmonella的超灵敏检测（灵敏度达到10E+0~10E+1CFU/mL）。

Enzyme-Induced Metallization of Gold Nanoparticles is a new method to generate the localized surface plasmon resonance (LSPR), which commonly reduces Ag+ ions on the surface of gold nanoparticles (AuNPs) to form Au@Ag core–shell NPs by the addition of silver nitrate to a solution containing citrate-stabilized AuNPs and some reducing agents, such as hydrogen peroxide, ascorbic acid and p-aminophenol. But, their applications were limited in practice because of poor stability. Glucose has better stability, and Ag+ ions can be reduced by the aldehyde group of glucose in the presence of ammonia. In the preliminary experiments, we found that the change of ammonia or glucose concentration can regulate the reduction rate of Ag+ ions on the surface of the gold nano-flowers (AuNFs), and produce a colorful color. Therefore, the applicant proposes a new ideal to develop a sensitive pELISA based on enzyme-induced metallization of AuNFs, in which the urease or sucrase will be introduced into a conventional immunoassay for producing NH3 or glucose, and thereby regulating the NH3 or glucose concentration. In order to further improve the sensitivity of pELISA, the silica nanoparticles carrying poly(acrylic acid) brushes will be suggested as the "container" of urease or sucrase to increase the enzyme loading capacity on the surface of bacteria. The improved pELISA will exhibit the ultra-sensitivity for detection of E.coli O157:H7、LM and Salmonella with the detection limit of 10E+0 ~ 10E+1CFU / mL. Taken together, this proposal aims to establish an ultrasensitive immunoassay to shorten the detection time of foodborne pathogens, and provides a new idea for rapid screening of foodborne pathogens.