Anti-OTC antibody-conjugated fluorescent magnetic/silica and fluorescent hybrid silica nanoparticles for oxytetracycline detection

This study presents two alternative fluorescent nanoparticle-based oxytetracycline (OTC) detection methods in milk samples. Rhodamine 6G-coated fluorescent hybrid silica nanoparticles and fluorescent magnetic/silica nanoparticles functionalized with anti-OTC antibodies were used in this test. The sandwich test format was utilized to compare anti-OTC antibody-conjugated fluorescent magnetic/silica nanoparticles with OTC/OTC antibody-conjugated fluorescent hybrid silica nanoparticles in an Eppendorf tube with magnetic separators. The magnetic separator helps to quickly retain all of the OTC captured by fluorescent magnetic core-shell nanoparticles in the milk sample. As a result, the assay time was dramatically shortened. The obtained linear range was 1.34 x 10-6 to 2.10 x 10-8 (M) (R 2 = 0.9954), the detection limit was 4.76 ng/mL, and the total assay time was 90 min. This approach was used to determine the OTC concentration in milk samples, and the maximum percentage (%) of interference was less than 3.0%, with a recovery rate of greater than 97.0%. This approach offers a high potential for residue detection in milk samples. With a total analysis period of less than 90 min, this approach provided the best way to determine the capture and detector nanoparticles' response.