TABLE 3.

Examples of optical biosensors for detection of whole bacterial cells^a

Target analyte(s)	Transducer signal	Sensor assembly	Bioreceptor(s)	LOD	Analyte(s)	Reference(s)
Various, e.g., Salmonella Typhimurium, Escherichia coli O157:H7, Shigella dysenteriae, Campylobacter jejuni	Fluorescence	NRL array sensor (fluorescence-based affinity assay)	Antibody, ganglioside receptors, oligosaccharides	2 × 103–8 × 104 CFU/ml	Food or environmental samples	35
Salmonella enterica, Listeria monocytogenes, Escherichia coli O157:H7	Fluorescence	Antibodies linked via biotin/avidin to optical fibers	Polyclonal antibody for capture, fluorescent monoclonal antibody or aptamer against surface protein InlA as reporter	103 CFU/ml	Artificially contaminated meat samples	50, 51
Escherichia coli	Fluorescence	Bioconjugated magnetic beads for capture, fluorescent polymeric micelles for reporting	Polyclonal anti-E. coli antibodies	15 cells/ml	Bacteria in buffer	37
Escherichia coli	Thin-film optical interference spectroscopy	Antibody-functionalized nanostructured oxidized porous silicon (PSiO2)	Anti-E. coli polyclonal antibody	104 cells/ml	Bacteria in buffer	52
Salmonella Typhimurium	Light scattering	Immunoagglutination assay using anti-Salmonella-conjugated polystyrene microparticles	Anti-Salmonella polyclonal antibody	10 CFU/ml	Liquid from processed raw chicken	53
Shewanella oneidensis	SERS	Silver nanoparticles sandwiched by analyte binding on optical fiber tip	NA	106 cells/ml	Bacteria in buffer	54
Escherichia coli, Staphylococcus aureus, Bacillus subtilis	SPR	Lectin-functionalized anisotropic silver nanoparticles	Potato lectin	1.5 × 104 CFU/ml	Bacteria in serum-spiked buffer	42
Escherichia coli O157:H7	Long-range SPR	Antibodies on SAM-gold surface/antibody-functionalized magnetic nanoparticles	Anti-E. coli antibody	50 CFU/ml	Bacteria in buffer	39
Escherichia coli	SPR	Bacteriophage covalently bound to SiO2 optical fibers	T4 bacteriophage	103 CFU/ml	Bacteria in buffer	41

^aAbbreviations: SERS, surface-enhanced Raman scattering; SPR, surface plasmon resonance; NA, not applicable.