Magnetic immunoassay (MIA) is a type of diagnostic immunoassay using magnetic beads as labels in lieu of conventional enzymes (ELISA), radioisotopes (RIA) or fluorescent moieties (fluorescent immunoassays)[1] to detect a specified analyte. MIA involves the specific binding of an antibody to its antigen, where a magnetic label is conjugated to one element of the pair. The presence of magnetic beads is then detected by a magnetic reader (magnetometer) which measures the magnetic field change induced by the beads. The signal measured by the magnetometer is proportional to the analyte (virus, toxin, bacteria, cardiac marker, etc.) concentration in the initial sample.
Magnetic beads are made of nanometric-sized iron oxide particles encapsulated or glued together with polymers. These magnetic beads range from 35 nm up to 4.5 μm. The component magnetic nanoparticles range from 5 to 50 nm and exhibit a unique quality referred to as superparamagnetism in the presence of an externally applied magnetic field. First discovered by Frenchman Louis Néel, Nobel Physics Prize winner in 1970, this superparamagnetic quality has already been used for medical application in Magnetic Resonance Imaging (MRI) and in biological separations, but not yet for labeling in commercial diagnostic applications. Magnetic labels exhibit several features very well adapted for such applications:[citation needed]
they are not affected by reagent chemistry or photo-bleaching and are therefore stable over time,
the magnetic background in a biomolecular sample is usually insignificant,
sample turbidity or staining have no impact on magnetic properties,
magnetic beads can be manipulated remotely by magnetism.
Detection
Magnetic Immunoassay (MIA) is able to detect select molecules or pathogens through the use of a magnetically tagged antibody. Functioning in a way similar to that of an ELISA or Western Blot, a two-antibody binding process is used to determine concentrations of analytes. MIA uses antibodies that are coating a magnetic bead. These anti-bodies directly bind to the desired pathogen or molecule and the magnetic signal given off the bound beads is read using a magnetometer. The largest benefit this technology provides for immunostaining is that it can be conducted in a liquid medium, where methods such as ELISA or Western Blotting require a stationary medium for the desired target to bind to before the secondary antibody (such as HRP [Horse Radish Peroxidase]) is able to be applied. Since MIA can be conducted in a liquid medium a more accurate measurement of desired molecules can be performed in the model system. Since no isolation must occur to achieve quantifiable results users can monitor activity within a system. Getting a better idea of the behavior of their target.[citation needed]
The manners in which this detection can occur are very numerous. The most basic form of detection is to run a sample through a gravity column that contains a polyethylene matrix with the secondary anti-body. The target compound binds to the antibody contained in the matrix, and any residual substances are washed out using a chosen buffer. The magnetic antibodies are then passed through the same column and after an incubation period, any unbound antibodies are washed out using the same method as before. The reading obtained from the magnetic beads bound to the target which is captured by the antibodies on the membrane is used to quantify the target compound in solution.[citation needed]
Also, because it is so similar in methodology to ELISA or Western Blot the experiments for MIA can be adapted to use the same detection if the researcher wants to quantify their data in a similar manner.
Magnetometers
A simple instrument can detect the presence and measure the total magnetic signal of a sample, however, the challenge of developing an effective MIA is to separate naturally occurring magnetic background (noise) from the weak magnetically labeled target (signal). Various approaches and devices have been employed to achieve a meaningful signal-to-noise ratio (SNR) for bio-sensing applications:[citation needed]
But improving SNR often requires a complex instrument to provide repeated scanning and extrapolation through data processing, or precise alignment of target and sensor of miniature and matching size. Beyond this requirement, MIA that exploits the non-linear magnetic properties of magnetic labels[citation needed] can effectively use the intrinsic ability of a magnetic field to pass through plastic, water, nitrocellulose, and other materials, thus allowing for true volumetric measurements in various immunoassay formats. Unlike conventional methods that measure the susceptibility of superparamagnetic materials, a MIA-based on non-linear magnetization eliminates the impact of linear dia- or paramagnetic materials such as sample matrix, consumable plastics and/or nitrocellulose. Although the intrinsic magnetism of these materials is very weak, with typical susceptibility values of –10−5 (dia) or +10−3 (para), when one is investigating very small quantities of superparamagnetic materials, such as nanograms per test, the background signal generated by ancillary materials cannot be ignored. In MIA based on non-linear magnetic properties of magnetic labels the beads are exposed to an alternating magnetic field at two frequencies, f1 and f2. In the presence of non-linear materials such as superparamagnetic labels, a signal can be recorded at combinatorial frequencies, for example, at f = f1 ± 2×f2. This signal is exactly proportional to the amount of magnetic material inside the reading coil.
This technology makes magnetic immunoassay possible in a variety of formats such as:
conventional lateral flow test by replacing gold labels with magnetic labels
vertical flow tests allowing for the interrogation of rare analytes (such as bacteria) in large-volume samples
MIA can also be used to monitor therapeutic drugs. A case report of a 53-year-old[6][full citation needed] kidney transplant patient details how the doctors were able to alter the quantities of the therapeutic drug.
References
^Zanut, A.; Fiorani, A.; Canola, S.; Saito, T.; Ziebart, N.; Rapino, S.; Rebeccani, S.; Barbon, A.; Irie, T.; Josel, H.; Negri, F.; Marcaccio, M.; Windfuhr, M.; Imai, K.; Valenti, G.; Paolucci, F. (2020). "Insights into the mechanism of coreactant electrochemiluminescence facilitating enhanced bioanalytical performance". Nat. Commun. 11 (1): 2668. Bibcode:2020NatCo..11.2668Z. doi:10.1038/s41467-020-16476-2. PMC7260178. PMID 32472057.
^Rife, J.C.; Miller, M.M.; Sheehan, P.E.; Tamanaha, C.R.; Tondra, M.; Whitman, L.J. (2003). "Design and performance of GMR sensors for the detection of magnetic microbeads in biosensors". Sensors and Actuators A: Physical. Elsevier BV. 107 (3): 209–218. doi:10.1016/s0924-4247(03)00380-7. ISSN 0924-4247.[verification needed]
^Nikitin, M. P.; Torno, M.; Chen, H.; Rosengart, A.; Nikitin, P. I. (2008). "Quantitative real-time in vivo detection of magnetic nanoparticles by their nonlinear magnetization". Journal of Applied Physics. AIP Publishing. 103 (7): 07A304. Bibcode:2008JAP...103gA304N. doi:10.1063/1.2830947. ISSN 0021-8979.[verification needed]
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Magnetic immunoassay MIA is a type of diagnostic immunoassay using magnetic beads as labels in lieu of conventional enzymes ELISA radioisotopes RIA or fluorescent moieties fluorescent immunoassays 1 to detect a specified analyte MIA involves the specific binding of an antibody to its antigen where a magnetic label is conjugated to one element of the pair The presence of magnetic beads is then detected by a magnetic reader magnetometer which measures the magnetic field change induced by the beads The signal measured by the magnetometer is proportional to the analyte virus toxin bacteria cardiac marker etc concentration in the initial sample Contents 1 Magnetic labels 2 Detection 3 Magnetometers 4 Uses 5 ReferencesMagnetic labels EditMagnetic beads are made of nanometric sized iron oxide particles encapsulated or glued together with polymers These magnetic beads range from 35 nm up to 4 5 mm The component magnetic nanoparticles range from 5 to 50 nm and exhibit a unique quality referred to as superparamagnetism in the presence of an externally applied magnetic field First discovered by Frenchman Louis Neel Nobel Physics Prize winner in 1970 this superparamagnetic quality has already been used for medical application in Magnetic Resonance Imaging MRI and in biological separations but not yet for labeling in commercial diagnostic applications Magnetic labels exhibit several features very well adapted for such applications citation needed they are not affected by reagent chemistry or photo bleaching and are therefore stable over time the magnetic background in a biomolecular sample is usually insignificant sample turbidity or staining have no impact on magnetic properties magnetic beads can be manipulated remotely by magnetism Detection EditMagnetic Immunoassay MIA is able to detect select molecules or pathogens through the use of a magnetically tagged antibody Functioning in a way similar to that of an ELISA or Western Blot a two antibody binding process is used to determine concentrations of analytes MIA uses antibodies that are coating a magnetic bead These anti bodies directly bind to the desired pathogen or molecule and the magnetic signal given off the bound beads is read using a magnetometer The largest benefit this technology provides for immunostaining is that it can be conducted in a liquid medium where methods such as ELISA or Western Blotting require a stationary medium for the desired target to bind to before the secondary antibody such as HRP Horse Radish Peroxidase is able to be applied Since MIA can be conducted in a liquid medium a more accurate measurement of desired molecules can be performed in the model system Since no isolation must occur to achieve quantifiable results users can monitor activity within a system Getting a better idea of the behavior of their target citation needed The manners in which this detection can occur are very numerous The most basic form of detection is to run a sample through a gravity column that contains a polyethylene matrix with the secondary anti body The target compound binds to the antibody contained in the matrix and any residual substances are washed out using a chosen buffer The magnetic antibodies are then passed through the same column and after an incubation period any unbound antibodies are washed out using the same method as before The reading obtained from the magnetic beads bound to the target which is captured by the antibodies on the membrane is used to quantify the target compound in solution citation needed Also because it is so similar in methodology to ELISA or Western Blot the experiments for MIA can be adapted to use the same detection if the researcher wants to quantify their data in a similar manner Magnetometers EditA simple instrument can detect the presence and measure the total magnetic signal of a sample however the challenge of developing an effective MIA is to separate naturally occurring magnetic background noise from the weak magnetically labeled target signal Various approaches and devices have been employed to achieve a meaningful signal to noise ratio SNR for bio sensing applications citation needed giant magneto resistive sensors and spin valves piezo resistive cantilevers inductive sensors superconducting quantum interference devices anisotropic magneto resistive rings and miniature Hall sensors 2 But improving SNR often requires a complex instrument to provide repeated scanning and extrapolation through data processing or precise alignment of target and sensor of miniature and matching size Beyond this requirement MIA that exploits the non linear magnetic properties of magnetic labels citation needed can effectively use the intrinsic ability of a magnetic field to pass through plastic water nitrocellulose and other materials thus allowing for true volumetric measurements in various immunoassay formats Unlike conventional methods that measure the susceptibility of superparamagnetic materials a MIA based on non linear magnetization eliminates the impact of linear dia or paramagnetic materials such as sample matrix consumable plastics and or nitrocellulose Although the intrinsic magnetism of these materials is very weak with typical susceptibility values of 10 5 dia or 10 3 para when one is investigating very small quantities of superparamagnetic materials such as nanograms per test the background signal generated by ancillary materials cannot be ignored In MIA based on non linear magnetic properties of magnetic labels the beads are exposed to an alternating magnetic field at two frequencies f1 and f2 In the presence of non linear materials such as superparamagnetic labels a signal can be recorded at combinatorial frequencies for example at f f1 2 f2 This signal is exactly proportional to the amount of magnetic material inside the reading coil This technology makes magnetic immunoassay possible in a variety of formats such as conventional lateral flow test by replacing gold labels with magnetic labels vertical flow tests allowing for the interrogation of rare analytes such as bacteria in large volume samples microfluidic applications and biochipIt was also described for in vivo applications 3 and for multiparametric testing Uses EditMIA is a versatile technique that can be used for a wide variety of practices Currently it has been used to detect viruses in plants to catch pathogens that would normally devastate crops such as Grapevine fanleaf virus 4 full citation needed and Potato virus X Its adaptations now include portable devices that allow the user to gather sensitive data in the field 5 full citation needed MIA can also be used to monitor therapeutic drugs A case report of a 53 year old 6 full citation needed kidney transplant patient details how the doctors were able to alter the quantities of the therapeutic drug References Edit Zanut A Fiorani A Canola S Saito T Ziebart N Rapino S Rebeccani S Barbon A Irie T Josel H Negri F Marcaccio M Windfuhr M Imai K Valenti G Paolucci F 2020 Insights into the mechanism of coreactant electrochemiluminescence facilitating enhanced bioanalytical performance Nat Commun 11 1 2668 Bibcode 2020NatCo 11 2668Z doi 10 1038 s41467 020 16476 2 PMC 7260178 PMID 32472057 Rife J C Miller M M Sheehan P E Tamanaha C R Tondra M Whitman L J 2003 Design and performance of GMR sensors for the detection of magnetic microbeads in biosensors Sensors and Actuators A Physical Elsevier BV 107 3 209 218 doi 10 1016 s0924 4247 03 00380 7 ISSN 0924 4247 verification needed Nikitin M P Torno M Chen H Rosengart A Nikitin P I 2008 Quantitative real time in vivo detection of magnetic nanoparticles by their nonlinear magnetization Journal of Applied Physics AIP Publishing 103 7 07A304 Bibcode 2008JAP 103gA304N doi 10 1063 1 2830947 ISSN 0021 8979 verification needed Yang et al 2008 a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help Rettcher et al 2015 a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help McMilin et al 2013 a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help Retrieved from https en wikipedia org w index php title Magnetic immunoassay amp oldid 1104355843, wikipedia, wiki, book, books, library,
