Fig. 1. Changes in the thickness of the superficial layer of the photonic crystal-based biosensor at the successive stages of surface preparation and the experiment studying the interaction between the polyelectrolyte-coated microbeads and the photonic crystal chip coated with an oppositely charged polyelectrolyte. A. Shows how the adlayer on the surface of the photonic crystal changed in thickness when the crystal was treated with amino groups (APTES) and subjected to the deposition of layers of oppositely charged polyelectrolytes poly(sodium 4-styrenesulfonate) (PSS) and poly(allylamine hydrochloride) (PAH). The thickness of the surface increased with every applied layer of polyelectrolytes. The effect of the sodium phosphate buffer (pH 8.0) containing 0.5 М NaCl pumped through the microfluidic cell is marked with a «Buffer» arrow. The microbeads used as a bacterial model were resuspended in the same buffer; the effect of the microbead suspension pumped through the microfluidic cell is marked with a «Microbeads» arrow. B. Shows how the thickness of the photonic crystal surface increased as the suspension of microbeads coated with poly(acrylic) acid (PAA) was pumped through the cell. The «Buffer» arrow represents a point at which the suspension of the microbeads was discontinued and the buffer was supplied to the flow cell. The figure also shows the results of theoretical modelling of microbeads binding to the surface of the photonic crystal (see the article)

Fig. 2. Detection of the exotoxin A of Pseudomonas aeruginosa by the biosensor based on the photonic crystal surface mode detection

Fig. 3. Detection of the heat-labile toxin LT of Escherichia coli by the biosensor based on the photonic crystal surface mode detection