Publications scientifiques
Magnetic Immunoassays
P. I. Nikitin et al. (2007). Sensor Letters, 5, 1, 296-9.
Résumé. New low-noise detection method has been developed and used for
design of a new type of biosensors based on detection of nano-sized superparamagnetic
particles or magnetic beads that serve as labels for biochemical reactions.
The method is based on non-linear magnetization of such particles. The
particles are exposed to a magnetic field having components at two frequencies
f1 and f2. The response is measured at combinatorial frequencies fi =
m · f1 + n · f2, where m and n are integers (one of them
can be zero). The integers can be varied to get the best signal-to-noise
ratio, e.g., fi = f1 ±2 · f2. Several readers have been designed
for the particles counting and used for different immunoassay formats,
including those compatible with immunoconcentration and magnetic enrichment
of antigens. Registration of 0.1 ng/ml of Y. pestis antigen and 103 cell/ml
of Salmonella typhimurium has been demonstrated. The developed biosensing
platforms can be used for medical diagnostics, points of care, food pathogen
detection, water analysis, etc.
New type of biosensor based on magnetic nanoparticle detection
Petr I. Nikitin et al. (2007). Journal of Magnetism and Magnetic Materials,
311, 445-9.
Résumé. A new type of biosensor has been developed based on detection
of nanosized superparamagnetic particles that serve as labels in bioreactions.
The method is based on non-linear magnetic material detection by a magnetic
field having components at two frequencies f1 and f2. The response is
measured at the combinatorial frequencies fi = mf1+nf2, where m and n
are integers, e.g., fi = f1 ± f2. Several highly sensitive readers of
superparamagnetic particles have been designed and used for development
of development of various formats of immunoassays, including those compatible
with immunoconcentration and magnetic enrichment of antigen.
Quantitative real-time in vivo detection of magnetic nanoparticles by their
nonlinear magnetization
M. P. Nikitin, Journal of Applied Physics 103, 07A304 (2008)
Résumé. A novel method of highly sensitive quantitative detection of magnetic nanoparticles (MP) in
biological tissues and blood system has been realized and tested in real time in vivo experiments.
The detection method is based on nonlinear magnetic properties of MP and the related device can
record a very small relative variation of nonlinear magnetic susceptibility up to 10−8 at room
temperature, providing sensitivity of several nanograms of MP in 0.1 ml volume. Real-time
quantitative in vivo measurements of dynamics of MP concentration in blood flow have been
performed. A catheter that carried the blood flow of a rat passed through the measuring device. After
an MP injection, the quantity of MP in the circulating blood was continuously recorded. The method
has also been used to evaluate the MP distribution between rat’s organs. Its sensitivity was compared
with detection of the radioactive MP based on isotope of 59Fe. The comparison of magnetic and
radioactive signals in the rat’s blood and organ samples demonstrated similar sensitivity for both
methods. However, the proposed magnetic method is much more convenient as it is safe, less
expensive, and provides real-time measurements in vivo.Moreover, the sensitivity of the method
can be further improved by optimization of the device geometry.