Persistent Luminescence Strontium Aluminate Nanoparticles as Reporters in Lateral Flow Assays

Abstract

Demand for highly sensitive, robust diagnostics and environmental monitoring methods has led to extensive research in improving reporter technologies. Inorganic phosphorescent materials exhibiting persistent luminescence are commonly found in electroluminescent displays and glowing paints but are not widely used as reporters in diagnostic assays. Persistent luminescence nanoparticles (PLNPs) offer advantages over conventional photoluminescent probes, including the potential for enhanced sensitivity by collecting time-resolved measurements or images with decreased background autofluorescence while eliminating the need for expensive optical hardware, superior resistance to photobleaching, amenability to quantitation, and facile bioconjugation schemes. We isolated rare-earth doped strontium aluminate PLNPs from larger-particle commercial materials by wet milling and differential sedimentation and water-stabilized the particles by silica encapsulation using a modified Stöber process. Surface treatment with aldehyde silane followed by reductive amination with heterobifunctional amine-poly(ethylene glycol)-carboxyl allowed covalent attachment of proteins to the particles using standard carbodiimide chemistry. NeutrAvidin PLNPs were used in lateral flow assays (LFAs) with biotinylated lysozyme as a model analyte in buffer and monoclonal anti-lysozyme HyHEL-5 antibodies at the test line. Preliminary experiments revealed a limit of detection below 100 pg/mL using the NeutrAvidin PLNPs, which was approximately an order of magnitude more sensitive than colloidal gold.

Nanoparticle-based lateral flow biosensors

“…worked with this materials to detect nucleic acids and antigens in complex matrixes with improved results in comparison to the ELISA tests Paterson et al (2014),. B.H.…”

Rare earth based nanostructured materials: synthesis, functionalization, properties and bioimaging and biosensing applications

“…they participate in the mechanism with changes in their number of oxidation), or they just emit light through a controlled and slow ET from the host material [281,282]. The most common matrices used for persistent luminescent materials are based on silicate, aluminate, gallogermanate and gallates [47,118,119,123,283,284].…”

Chemically engineered persistent luminescence nanoprobes for bioimaging

“…In 2014, Willson and co-workers used the same matrix for the development of new in vitro diagnostic tests 132. The demand for reliable diagnostic tests for pathogens and disease biomarkers in low-resource and point-of-care (POC) settings has led to significant research in developing new assay technologies and improved photoluminescent reporters 133.…”

“…One of the most promising assay formats for POC diagnostics is the immuno-chromatographic lateral flow assay (LFA), which is widely known from its use in home pregnancy tests. In 2014, Wilson and co-workers demonstrated the use of strontium aluminate PLNPs as reporters in LFAs with biotinylated hen egg lysozyme (bHEL) as a model analyte 132. As discussed in the previous example, strontium aluminate hydrolyzes in water to form non luminescent aluminum hydroxide precipitate and soluble strontium hydroxide 134.…”