High Sensitivity Gram-Negative Bacteria Biosensor Based on a Small-Molecule Modified Surface Plasmon Resonance Chip Studied Using a Laser Scanning Confocal Imaging-Surface Plasmon Resonance System

The highly sensitive and rapid detection and distinction of gram-negative bacteria are essential for the early diagnosis and accurate medical treatment of bacterial infection. In this work, we investigated a new selective and sensitive method of detecting gram-negative bacteria based on a small molecule modified sensor chip by a laser scanning confocal imaging-surface plasmon resonance (LSCI-SPR) system. The small molecule (polymyxin B) strongly interacted with bacteria cell membrane. SPR signals changed with SYTO 9 stained bacteria concentrations, and fluorescence images were recorded at the same time. Results showed that Escherichia coli were distinguished clearly with a limit of detection (LOD) of 1.0 x 10(2) CFU/mL for Escherichia coli. Moreover, a good linear relationship was observed between bacteria concentrations and SPR signals from 1.0 x 10(2) CFU/mL to 1.0 x 10(6) CFU/mL with a linear coefficient R-2 of 0.99146. All these results indicated that this small-molecule modified sensor can be used for quantitative detection of known gram-negative bacteria and qualitative distinction of unknown gram-negative bacteria within 10 min each sample in real-time. (C) 2017 Elsevier B.V. All rights reserved.