Lipid–Polymer Hybrids Encapsulating Iron-Oxide Nanoparticles as a Label for Lateral Flow Immunoassays

Abstract

The feasibility of using Superparamagnetic Iron Oxide Nanoparticles (SPIONs) encapsulated by lipid–polymer nanoparticles as labels in lateral flow immunoassays (LFIA) was studied. First, nanoparticles were synthesized with average diameters between 4 and 7 (nm) through precipitation in W/O microemulsion and further encapsulated using lipid–polymer nanoparticles. Systems formulated were characterized in terms of size and shape by DLS (Nanozetasizer from Malvern) and TEM. After encapsulation, the average size was around (≈20 and 50 nm). These controlled size agglomerates were tested as labels with a model system based on the biotin–neutravidin interaction. For this purpose, the encapsulated nanoparticles were conjugated to neutravidin using the carbodiimide chemistry, and the LFIA was carried out with a biotin test line. The encapsulated SPIONs showed that they could be promising candidates as labels in LFIA test. They would be useful for immunomagnetic separations, that could improve the limits of detection by means of preconcentration.

Fe3O4@Au Core–Shell Magnetic Nanoparticles for the Rapid Analysis of E. coli O157:H7 in an Electrochemical Immunoassay

“…SPIONs allow the sample concentration and elimination of interferents with efficient washing steps due to their magnetic properties, thus improving the biosensors' performance [14,19]. These nanoparticles, with a typical diameter lower than 20 nm, rapidly respond to an external magnetic field and can be easily redispersed after the magnet is removed due to their superparamagnetic properties at room temperature [19,20]. This property can also increase the probability of detecting the target analyte in a small volume of sample through electrochemical biosensors [11].…”