Long period grating based biosensor for the detection of Escherichia coli bacteria

In this paper we report a stable, label-free, bacteriophage-based detection of Escherichia coli (E. coli) using ultra sensitive long-period fiber gratings (LPFGs). Bacteriophage T4 was covalently immobilized on optical fiber surface and the E. coli binding was investigated using the highly accurate spectral interrogation mechanism. In contrast to the widely used surface plasmon resonance (SPR) based sensors, no moving part or metal deposition is required in our sensor, making the present sensor extremely accurate, very compact and cost effective. We demonstrated that our detection mechanism is capable of reliable detection of E. coli concentrations as low as 103 cfu/ml with an experimental accuracy greater than 99%.

► A stable, label-free, bacteriophage-based detection of E. coli using ultra sensitive long-period gratings is demonstrated.
► E. coli binding by covalently immobilized bacteriophage T4 is investigated using the spectral interrogation mechanism.
► No moving part or metallization is required in our sensor, making it extremely accurate, very compact and cost effective.
► The detection mechanism is capable of reliable detection of E. coli concentrations as low as 103 cfu/ml with an experimental accuracy > 99%.
► We present the SEM images to confirm a reliable binding of E. coli bacteria to the optical fiber surface.