Characterization of magnetic relaxation when biofunctionalized magnetic nano-particles are associated with biomarkers in the liquid state in biomedical applications. Issue 8 (23rd January 2018)

• Record Type: Journal Article
• Authors: Liao, Shu-Hsien; Huang, Han-Sheng; Chen, Jean-Hong; Su, Yu-Kai; Tong, Yuan-Fu
• Is Part Of: RSC advances. Volume 8:Issue 8(2018)
• Page Start: 4057
• Page End: 4062
• Publication Date: 2018-01-23
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c7ra12634d
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : This study determined the characteristics of the time-dependent effective relaxation time τ eff and magnetization M when biofunctionalized magnetic nanoparticles (BMNPs) associated with biomarkers in a liquid immunoassay. Abstract : This study determined the characteristics of the time-dependent effective relaxation time τ eff and magnetization M when biofunctionalized magnetic nanoparticles (BMNPs) associated with biomarkers in a liquid immunoassay. Carcinoembryonic antigen (CEA) was used as the biomarker. BMNP is an anti-CEA that was coated onto dextran-coated Fe3 O4 and labeled as Fe3 O4 -anti-CEA. The phase lag θ of M with respect to the applied field H was measured using a sensitive homemade alternative-current susceptometer, and θ was measured using lock-in detection. The results were used to estimate τ eff using the relationship tan θ ( t ) = ωτ eff ( t ), where 2π f = ω and f is the excitation frequency. Δ τ eff increased with Φ CEA, where Δ τ eff was the increment of τ eff after Fe3 O4 -anti-CEA associated with CEA, and Φ CEA was the concentration of CEA. Additionally, M enhanced when Φ CEA increased. We attributed these enhancements to magnetic dipole–dipole interactions among MNPs that contributed extra M and in turn enhanced τ eff . Magnetic clusters after the association were verified using a transmission electron microscope. This study established the relationship between Δ τ eff / τ eff, 0 and Φ CEA, where τ eff, 0 = τ eff ( Φ CEA = 0), allowing the assay of an unknown amount of CEA molecules.