Bacterial infections are considered as a critical healthcare concern worldwide. Timely infection detection is crucial to effective antibiotic administration which can reduce the severity of infection and the occurrence of antibiotic resistance. We have developed label–free polydiacetylene (PDA) liposome-based colorimetric biosensor to detect and identify bacterial cultures at the genus and species level with naked eyes by simple color change. We found that among the various liposomal systems, moderate concentration of PDA, phospholipids and cholesterol in liposome assemblies can greatly influence the sensitivity to different bacteria, exhibiting unique chromatic properties of each bacterial strain. The strikingly different chromatic color change was due to the various mechanisms of interactions between bacterial toxins and biomimetic lipid bilayers. Furthermore, increase of cholesterol in liposome assemblies greatly enhanced the sensitivity of bacterial strains related to membrane destruction mediated by pore-formation mechanism such as S. aureus and E.coli, whereas the detection of the two bacterial strains was believed to rely on the specific recognition elements coupled with PDA moiety. As a proof of concept, a colorimetric finger-print array for distinguishing 6 bacterial species was studied. Particularly, the proposed bacterial detection platform is achieved through the interaction between bacterially secreted toxins and liposome bilayers instead of specific recognition of receptors-ligands. The results of both response time and sensitivity of label-free-liposome-based system show superior to previous reports on chromatic bacterial detection assays. By combing these results, the label-free-liposome-based colorimetric sensing platform shows great importance as a bacterial-sensing and discrimination platform.

细菌感染被认为是世界范围内一个重要的医疗保健问题。及时检测感染对于有效施用抗生素至关重要，可以降低感染的严重程度和抗生素耐药性的发生。我们开发了基于无标记聚二乙炔 (PDA) 脂质体的比色生物传感器，通过简单的颜色变化，用肉眼在属和种水平上检测和识别细菌培养物。我们发现，在各种脂质体系统中，脂质体组件中中等浓度的 PDA、磷脂和胆固醇可以极大地影响对不同细菌的敏感性，表现出每种菌株独特的颜色特性。显着不同的颜色变化是由于细菌毒素和仿生脂质双层之间的各种相互作用机制。此外，脂质体组装体中胆固醇的增加大大增强了与由孔形成机制介导的膜破坏相关的细菌菌株的敏感性，例如S. aureus和E.coli，而两种细菌菌株的检测被认为依赖于与 PDA 部分偶联的特定识别元件。作为概念证明，研究了用于区分 6 种细菌的比色指纹阵列。特别是，所提出的细菌检测平台是通过细菌分泌的毒素和脂质体双层之间的相互作用而不是受体-配体的特异性识别来实现的。基于无标记脂质体的系统的响应时间和灵敏度结果均优于先前关于染色细菌检测分析的报告。通过结合这些结果，基于无标记脂质体的比色传感平台显示出作为细菌传感和识别平台的重要性。