Photonic stop band - Fluorophore Overlap in inverse structure Enhances E. coli Detection via Fluorescence Imaging

Enhancing fluorescence image brightness is critical for improving the detection sensitivity in analytical applications. In this study, we evaluated the respective contributions of ( i ) the overlap between the photonic stop band (PSB) wavelength (λ _PSB ) of a hydrogel-based inverse opal photonic crystal (IOPC) and the emission wavelength (λ _emi ) of a fluorescent dye, and ( ii ) the pore diameter ( d ) of the IOPC, which determines the fluorophore loading capacity, to the overall fluorescence intensity. The overlap was selected by employing a consistent d and a specific dye, Alexa Fluor™ 488 (A488). Meanwhile, the variation in the fluorescence intensity ( I _fluor .) with respect to d was normalized, showing that although d reached 90% of the value at which wavelength overlap occurred ( d _overl .), I _fluor . increased to only 59%. However, when d increased to 110% and 125% the value of d _overl ., I _fluor reached only 75.6% and 77.1%, respectively. This suggested that the overlap effect was a kye factor contributing to the enhancement of the I _fluor . compared to the contribution from an increase in d . In addition, this result highlighted for the potential application of the IOPC with overlapping between λ _PSB and λ _emi to the detection of Escherichia coli ( E. coli ). Although IOPC samples with d reached 110% and 125% the value of d _overl were used, I _fluor . only reached 71.6% and 78.4%, respectively, of the value at which the overlap occurs. This indicated the potential application of the hydrogel IOPC exhibiting the overlap effect in the analytical field through fluorescence imaging.