Rapid label-free detection of Pseudomonas aeruginosa using a fluidic grating chip with a reflective laser system

Stripe arrays of poly(methacrylic acid) (PMAA) brushes were grafted using a photoresist template to fabricate one-dimensional photonic crystal (OPCs). The as-prepared samples were first bound with protein G to immobilize and orient tails of the antibody of Pa (abY). A fluidic diffraction chip based on the abY-tailed PMMA OPC was fabricated to examine the ability of Pa detection from whole blood specimen. Pa was attached to the abY-tailed PMMA OPC after flowing through the fluidic chip, which changed the diffraction intensity. A laser beam was employed to analyze the reflective signals of OPCs at an incident angle of 45°. The abY-tailed PMAA OPC possessed an optical feature with a characteristic diffraction effect such that the projection of the laser beam on the plane of the OPC chip was parallel to the strips in SII configurations, whereas they were perpendicular in ST configurations. The degree of the diffraction intensity exhibited a linear response to Pa at concentrations from 102 to 107 CFU mL−1, and the limit of detection was 100 CFU mL−1, indicating the excellent sensitivity in Pa-spiked whole blood samples. The proposed platform provides a rapid, label-free method for Pa detection to improve the administration of antibiotics in a timely manner.