Characterization of magnetite nanoparticles for SQUID-relaxometry and magnetic needle biopsy

Abstract

Magnetite nanoparticles (Chemicell SiMAG-TCL) were characterized by SQUID-relaxometry, susceptometry, and TEM. The magnetization detected by SQUID-relaxometry was 0.33% of that detected by susceptometry, indicating that the sensitivity of SQUID-relaxometry could be significantly increased through improved control of nanoparticle size. The relaxometry data were analyzed by the moment superposition model (MSM) to determine the distribution of nanoparticle moments. Analysis of the binding of CD34-conjugated nanoparticles to U937 leukemia cells revealed 60,000 nanoparticles per cell, which were collected from whole blood using a prototype magnetic biopsy needle, with a capture efficiency of >65% from a 750 µl sample volume in 1 minute. KeywordsMagnetite; Nanoparticle; Magnetorelaxometry; SQUID detection; Susceptometry; Antibodyconjugation We are developing SQUID (Superconducting Quantum Interference Device) relaxometry as a highly-sensitive platform for detecting and localizing superparamagnetic iron oxide nanoparticles specifically bound to cell-surface antigens (or other disease targets) in vivo. Preliminary in vitro experiments suggest that this technology will be capable of detecting just a few thousand cells located several centimeters from the sensors, enabling the early detection of cancer, or other diseases, in human subjects [1]. Currently we are investigating this methodology for the specific detection of breast cancer, transplant rejection, Alzheimer's disease, and ovarian cancer. Further, as we develop other clinical applications of targeted

A quantitative study of particle size effects in the magnetorelaxometry of magnetic nanoparticles using atomic magnetometry

“…Many of the earlier studies used multi-core particles, while more recently larger single-core magnetic particles have shown large magnetic signals in observation windows ranging from 50 ms to 2 s [15]. Those and others studies [16][17][18] have demonstrated that (SQUID-based) MRX has a high potential for biomedical imaging applications.…”

Selective Nanoparticles in Microextraction

“…The use of MNPs coated with anti-CD34 antibody can improve this performance. (38,39) This type of NPs presents a high affinity toward leukemia cells as it has been proved by imaging, when a leukemia cell line (U9337) is incubated with immuno-MNPs and bare-MNPs (unconjugated NPs). The immuno-MNPs bind to the cell surface due to the antigen recognition, while no (visual) interaction is observed for the bare-MNPs.…”

Nanopharmaceuticals (part 2): products in the pipeline

“…The CD34-NPs-containing cells are attracted to the magnets in the needle and they are liberated into media to be further analyzed by SQUID relaxometry. 40 In SQUID relaxometry, particles are briefly magnetized by a pulsed magnetic field (approximately 38 Gauss) and detected by magnetization decay over time in a zero field using the SQUID sensor. The SQUID sensor detects only the relaxation times that fall within 50 milliseconds to 2 seconds, as seen in Figure 3.…”