• The effect of the spacing between luminescent films of oxygen sensors was studied.
• Fluorophore layers were spaced by different combinations of polyelectrolytes.
• An appropriate spacing between luminescent films prevents from the self-quenching.
• Sensors sensitivity and linearity of the calibration curves can be optimized.
•Morphology of the embedding matrices determines the optimal number of spacing layers.
In this work, different luminescence-based optical fiber oxygen sensors have been fabricated by means of the Layer-by-Layer nanoassembly technique. The sensing material employed has been a platinum metalloporphyrin, platinum tetrakis pentafluorophenylporphine (Pt-TFFP), which has been entrapped into anionic micelles. Poly(diallyldimethylammonium chloride) (PDDA), polyethyleneimine (PEI) and poly(allylamine hydrochloride) (PAH) have been utilized as cationic polyelectrolytes. With the aim of avoiding self-quenching and optimizing sensors in terms of sensitivity and linearity of the calibration curves, the spacing (thickness) between the fluorophore films has been tuned by introducing poly(acrylic acid) (PAA) between the cationic layers. The morphology of the resultant sensors has been analyzed with an Atomic Force Microscope. It has been found that the number of spacing layers between the luminescent ones is determined by the features of the employed polycation.
Keywords: Luminescent sensor; Self-quenching; Fluorophore distance; Layer-by-Layer nanoassembly