研究目的
Investigating the integration of dielectrophoresis (DEP) into surface plasmon resonance (SPR) biosensors to overcome diffusion-limited mass transport of bacteria to the sensing surface, thereby improving the limit of detection (LOD) for bacterial detection.
研究成果
The integration of DEP and SPR into a single iSPR chip significantly improved the LOD for E. coli detection by nearly five orders of magnitude compared to conventional SPR chips. The iSPR chip demonstrated a LOD of ~3.0 x 102 CFU/mL, attributed to increased mass transport of bacterial cells to the IDE surface through DEP. Selective detection of E. coli over non-target S. epidermidis was enabled through secondary antibody amplification. This strategy holds great potential for rapid, sensitive, and specific detection of bacteria in various applications.
研究不足
The study is limited by the dependency of SP generation on the presence of discontinuities in the Au films used to define the width of the IDEs. Additionally, the technique's applicability in complex media and its scalability for high-throughput screening were not extensively explored.
1：Experimental Design and Method Selection:
The study involved the development of interdigitated SPR (iSPR) chips with dually functional interdigitated electrodes (IDEs) to sustain SPR and increase bacterial mass transport through DEP. The IDEs were defined into 50 nm thick Au films with fixed electrode gaps (EG = 5 μm) and varied electrode widths (EW = 10, 20, and 100 μm). The iSPR chips were compared against conventional SPR chips for their ability to support SPR and enhance bacterial detection.
2：Sample Selection and Data Sources:
Escherichia coli (ATCC 25922) and Staphylococcus epidermidis (ATCC 14990) were used as target and non-target bacteria, respectively. Bacterial suspensions were adjusted to concentrations ranging from 103 to 108 CFU/mL.
3：List of Experimental Equipment and Materials:
A custom-built, four-channel SPR device in the Kretschmann configuration was used for SPR experiments. IDEs were fabricated using photolithography, soft lithography, and chemical etching. A function generator supplied a 5 Vpp AC voltage potential at 500 Hz across the iSPR chips for DEP application.
4：Experimental Procedures and Operational Workflow:
The surfaces of iSPR chips were modified with mannose to target the FimH adhesin of E. coli. Bacterial suspensions were introduced into the flow channels of the SPR instrument, and DEP was applied simultaneously. SPR wavelength shifts were monitored in real-time.
5：Data Analysis Methods:
The SPR wavelength shifts were analyzed to determine the LOD for E. coli detection. Secondary antibody amplification was used to selectively enhance the detection of target bacteria.
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