title: Optimizing Blue Persistent Luminescence in (Sr1-δBaδ)2MgSi2O7:Eu2+,Dy3+via Solid Solution for Use in Point-of-Care Diagnostics.
abstract: Inorganic persistent luminescent phosphors are an excellent class of optical reporters for enabling sensitive point-of-care diagnostics, particularly with smartphone-based biosensing devices in testing formats such as the lateral flow assay (LFA). Here, the development of persistent phosphors for this application is focused on the solid solution (Sr1-δBaδ)2MgSi2O7:Eu2+,Dy3+(δ = 0, 0.125, 0.25, 0.375), which is prepared using a high-temperature solid-state reaction as confirmed by synchrotron X-ray powder diffraction. The substitution of barium for strontium enables control over the Eu2+5d-orbital crystal field splitting (CFS) as a tool for tuning the emission wavelength while maintaining luminescence lifetimes >9 min across the composition range. Thermoluminescence measurements of the solid solution provide evidence that trap states contribute to the persistent lifetimes with the trap depths also remaining constant as a function of composition. Time-gated luminescence images of these compounds are captured on a smartphone arranged in a layout to mimic a point-of-care test and demonstrate the viability of using these materials as optical reporters. Moreover, comparing the blue-emitting (Sr0.625Ba0.375)2MgSi2O7:Eu2+,Dy3+and the green-emitting SrAl2O4:Eu2+,Dy3+in a single LFA-type format shows these two compounds can be detected and resolved simultaneously, thereby permitting the development of a multiplexed LFA.
authors.affiliation: Department of Chemistry, University of Houston , Houston, Texas 77204-5003, United States.
authors.forename: Erin
authors.initials: E
authors.lastname: Finley
authors.affiliation: Department of Chemistry, University of Houston , Houston, Texas 77204-5003, United States.
authors.forename: Angelica
authors.initials: A
authors.lastname: Cobb
authors.affiliation: Department of Chemistry, University of Houston , Houston, Texas 77204-5003, United States.
authors.forename: Anna
authors.initials: A
authors.lastname: Duke
authors.affiliation: Luminostics Inc., Houston, Texas 77204, United States.|Department of Chemical and Biomolecular Engineering, University of Houston , Houston, Texas 77204, United States.
authors.forename: Andrew
authors.initials: A
authors.lastname: Paterson
authors.affiliation: Department of Chemistry, University of Houston , Houston, Texas 77204-5003, United States.
authors.forename: Jakoah
authors.initials: J
authors.lastname: Brgoch
mesh_terms: D003116:Color; D004419:Dysprosium; D005063:Europium; D049449:Luminescence; D017633:Magnesium Silicates; D019095:Point-of-Care Systems; D013324:Strontium
chemical_list: D017633:Magnesium Silicates; C005013:Florisil; D004419:Dysprosium; D005063:Europium; D013324:Strontium
keywords: biosensing; phosphor; solid solution; thermoluminescence; time-gated imaging