M13KO7 bacteriophage functionalization Viruses are infectious agents that can cause disease in humans, plants, and animals; antibodies are typically used in immunoassays to detect viruses in biological
samples. The M13KO7 bacterial virus was used as a model system to determine if the large (approximately 2 μm in length; 16,400 kDa) M13KO7 could be directly bound to and detected on the PSi BSW/BSSW sensor surface. The M13KO7 bacteriophage is a low-cost, readily available, nonhazardous E. coli bacterial virus that can be readily detected using commercially available antibodies GDC-0449 mouse [18, 19]. The virus was covalently cross-linked to the PSi surface via APTES and GA linkers. APTES was attached IWP-2 research buy as described
above. GA is a homobifunctional cross-linker that can bind to and covalently link molecules through their free amines. A 2.5% GA in phosphate buffered saline (PBS) buffer solution was used to cross-link the APTES free amines on the sensor surface to the free amines on M13KO7 suspended in solution on the sensor surface. After a 30-min GA incubation step, a 1% sodium cyanoborohydride (Sigma-Aldrich, St. Louis, MO, USA) in PBS buffer solution was applied, followed by a 30-min incubation step to stabilize the Schiff base bonds formed during GA cross-linking . The M13KO7 (0.32 mg/ml carbonate/bicarbonate buffer, pH ~ 10) was diluted to a final concentration of 32 μg/ml in PBS buffer (final pH ~ 9.5) and applied to the sensor surface for 20 min at room temperature. The device was thoroughly rinsed with DI water. Figure 2b shows a top view SEM image of the M13KO7 bacteriophage immobilized on the PSi surface. Coulombic interactions prevent a uniform self-assembled monolayer due to the negatively charged nature of the virus. Results and discussion A resonance condition is distinctly excited when the effective index of a BSW or BSSW mode is matched by the coupling conditions of either a prism or diffraction grating. Prism coupling is compatible with existing
surface plasmon resonance biosensing instrumentation. Grating coupling SAR302503 cell line allows for more compact devices, which could be Astemizole used for point of care diagnostics with microfluidics integration . The BSW mode is confined by the band gap created by the Bragg mirror and by total internal reflection near the surface. Similarly, by reducing the optical thickness of one or more layers within the multilayer through the introduction of a step or gradient refractive index profile, BSSW modes with different effective indices can be supported within the multilayer. The implementation of a single step to break the periodicity of the Bragg mirror refractive index profile shifts the band edge of the Bragg mirror and gives rise to a single BSSW mode confined within the corresponding layer with reduced optical thickness.