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15 pages, 2289 KiB

Open AccessArticle

Studies towards hcTnI Immunodetection Using Electrochemical Approaches Based on Magnetic Microbeads

by Alejandro Hernández-Albors, Gloria Colom, J.-Pablo Salvador and M.-Pilar Marco

Sensors 2018, 18(8), 2457; https://doi.org/10.3390/s18082457 - 29 Jul 2018

Cited by 9 | Viewed by 3478

Abstract

Different electrochemical strategies based on the use of magnetic beads are described in this work for the detection of human cardiac troponin I (hcTnI). hcTnI is also known as the gold standard for acute myocardial infarction (AMI) diagnosis according to the different guidelines [...] Read more.

Different electrochemical strategies based on the use of magnetic beads are described in this work for the detection of human cardiac troponin I (hcTnI). hcTnI is also known as the gold standard for acute myocardial infarction (AMI) diagnosis according to the different guidelines from the European Society of Cardiology (ESC) and the American College of Cardiology (ACC). Amperometric and voltamperometric sandwich magnetoimmunoassays were developed by biofunctionalization of paramagnetic beads with specific antibodies. These bioconjugates were combined with biotinylated antibodies as detection antibodies, with the aim of testing different electrochemical transduction principles. Streptavidin labeled with horseradish peroxidase was used for the amperometric magnetoimmunoassay, reaching a detectability of 0.005 ± 0.002 µg mL⁻¹ in 30 min. Cadmium quantum dots-streptavidin bioconjugates were used in the case of the voltamperometric immunosensor reaching a detectability of 0.023 ± 0.014 µg mL⁻¹. Full article

(This article belongs to the Special Issue Magnetic Materials Based Biosensors)

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14 pages, 7975 KiB

Open AccessArticle

Biosensing System for Concentration Quantification of Magnetically Labeled E. coli in Water Samples

by Anna Malec, Georgios Kokkinis, Christoph Haiden and Ioanna Giouroudi

Sensors 2018, 18(7), 2250; https://doi.org/10.3390/s18072250 - 12 Jul 2018

Cited by 7 | Viewed by 3497

Abstract

Bacterial contamination of water sources (e.g., lakes, rivers and springs) from waterborne bacteria is a crucial water safety issue and its prevention is of the utmost significance since it threatens the health and well-being of wildlife, livestock, and human populations and can lead [...] Read more.

Bacterial contamination of water sources (e.g., lakes, rivers and springs) from waterborne bacteria is a crucial water safety issue and its prevention is of the utmost significance since it threatens the health and well-being of wildlife, livestock, and human populations and can lead to serious illness and even death. Rapid and multiplexed measurement of such waterborne pathogens is vital and the challenge is to instantly detect in these liquid samples different types of pathogens with high sensitivity and specificity. In this work, we propose a biosensing system in which the bacteria are labelled with streptavidin coated magnetic markers (MPs—magnetic particles) forming compounds (MLBs—magnetically labelled bacteria). Video microscopy in combination with a particle tracking software are used for their detection and quantification. When the liquid containing the MLBs is introduced into the developed, microfluidic platform, the MLBs are accelerated towards the outlet by means of a magnetic field gradient generated by integrated microconductors, which are sequentially switched ON and OFF by a microcontroller. The velocities of the MLBs and that of reference MPs, suspended in the same liquid in a parallel reference microfluidic channel, are calculated and compared in real time by a digital camera mounted on a conventional optical microscope in combination with a particle trajectory tracking software. The MLBs will be slower than the reference MPs due to the enhanced Stokes’ drag force exerted on them, resulting from their greater volume and altered hydrodynamic shape. The results of the investigation showed that the parameters obtained from this method emerged as reliable predictors for E. coli concentrations. Full article

(This article belongs to the Special Issue Magnetic Materials Based Biosensors)

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13 pages, 1079 KiB

Open AccessArticle

Shear Elasticity of Magnetic Gels with Internal Structures

by Dmitry Borin, Dmitri Chirikov and Andrey Zubarev

Sensors 2018, 18(7), 2054; https://doi.org/10.3390/s18072054 - 27 Jun 2018

Cited by 15 | Viewed by 2887

Abstract

We present the results of the theoretical modeling of the elastic shear properties of a magnetic gel, consisting of soft matrix and embedded, fine magnetizable particles, which are united in linear chain-like structures. We suppose that the composite is placed in a magnetic [...] Read more.

We present the results of the theoretical modeling of the elastic shear properties of a magnetic gel, consisting of soft matrix and embedded, fine magnetizable particles, which are united in linear chain-like structures. We suppose that the composite is placed in a magnetic field, perpendicular to the direction of the sample shear. Our results show that the field can significantly enhance the mechanical rigidity of the soft composite. Theoretical results are in quantitative agreement with the experiments. Full article

(This article belongs to the Special Issue Magnetic Materials Based Biosensors)

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12 pages, 2459 KiB

Open AccessArticle

A Multi-Region Magnetoimpedance-Based Bio-Analytical System for Ultrasensitive Simultaneous Determination of Cardiac Biomarkers Myoglobin and C-Reactive Protein

by Zhen Yang, Huanhuan Wang, Pengfei Guo, Yuanyuan Ding, Chong Lei and Yongsong Luo

Sensors 2018, 18(6), 1765; https://doi.org/10.3390/s18061765 - 1 Jun 2018

Cited by 21 | Viewed by 3830

Abstract

Cardiac biomarkers (CBs) are substances that appear in the blood when the heart is damaged or stressed. Measurements of the level of CBs can be used in course of diagnostics or monitoring the state of the health of group risk persons. A multi-region [...] Read more.

Cardiac biomarkers (CBs) are substances that appear in the blood when the heart is damaged or stressed. Measurements of the level of CBs can be used in course of diagnostics or monitoring the state of the health of group risk persons. A multi-region bio-analytical system (MRBAS) based on magnetoimpedance (MI) changes was proposed for ultrasensitive simultaneous detection of CBs myoglobin (Mb) and C-reactive protein (CRP). The microfluidic device was designed and developed using standard microfabrication techniques for their usage in different regions, which were pre-modified with specific antibody for specified detection. Mb and CRP antigens labels attached to commercial Dynabeads with selected concentrations were trapped in different detection regions. The MI response of the triple sensitive element was carefully evaluated in initial state and in the presence of biomarkers. The results showed that the MI-based bio-sensing system had high selectivity and sensitivity for detection of CBs. Compared with the control region, ultrasensitive detections of CRP and Mb were accomplished with the detection limits of 1.0 pg/mL and 0.1 pg/mL, respectively. The linear detection range contained low concentration detection area and high concentration detection area, which were 1 pg/mL–10 ng/mL, 10–100 ng/mL for CRP, and 0.1 pg/mL–1 ng/mL, 1 n/mL–80 ng/mL for Mb. The measurement technique presented here provides a new methodology for multi-target biomolecules rapid testing. Full article

(This article belongs to the Special Issue Magnetic Materials Based Biosensors)

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11 pages, 605 KiB

Open AccessFeature PaperArticle

Magnetorelaxometry in the Presence of a DC Bias Field of Ferromagnetic Nanoparticles Bearing a Viscoelastic Corona

by Victor Rusakov and Yuriy Raikher

Sensors 2018, 18(5), 1661; https://doi.org/10.3390/s18051661 - 22 May 2018

Cited by 11 | Viewed by 3551

Abstract

With allowance for orientational Brownian motion, the magnetorelaxometry (MRX) signal, i.e., the decay of magnetization generated by an ensemble of ferromagnet nanoparticles, each of which bears a macromolecular corona (a loose layer of polymer gel) is studied. The rheology of corona is modelled [...] Read more.

With allowance for orientational Brownian motion, the magnetorelaxometry (MRX) signal, i.e., the decay of magnetization generated by an ensemble of ferromagnet nanoparticles, each of which bears a macromolecular corona (a loose layer of polymer gel) is studied. The rheology of corona is modelled by the Jeffreys scheme. The latter, although comprising only three phenomenological parameters, enables one to describe a wide spectrum of viscoelastic media: from linearly viscous liquids to weakly-fluent gels. The “transverse” configuration of MRX is considered where the system is subjected to a DC (constant bias) field, whereas the probing field is applied perpendicularly to the bias one. The analysis shows that the rate of magnetization decay strongly depends on the state of corona and slows down with enhancement of the corona elasticity. In addition, for the case of “transverse” MRX, we consider the integral time, i.e., the characteristic that is applicable to relaxation processes with an arbitrary number of decay modes. Expressions for the dependence of the integral time on the corona elasticity parameter and temperature are derived. Full article

(This article belongs to the Special Issue Magnetic Materials Based Biosensors)

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9 pages, 10374 KiB

Open AccessArticle

Eight-Channel AC Magnetosusceptometer of Magnetic Nanoparticles for High-Throughput and Ultra-High-Sensitivity Immunoassay

by Jen-Jie Chieh, Wen-Chun Wei, Shu-Hsien Liao, Hsin-Hsein Chen, Yen-Fu Lee, Feng-Chun Lin, Ming-Hsien Chiang, Ming-Jang Chiu, Herng-Er Horng and Shieh-Yueh Yang

Sensors 2018, 18(4), 1043; https://doi.org/10.3390/s18041043 - 30 Mar 2018

Cited by 17 | Viewed by 3941

Abstract

An alternating-current magnetosusceptometer of antibody-functionalized magnetic nanoparticles (MNPs) was developed for immunomagnetic reduction (IMR). A high-sensitivity, high-critical-temperature superconducting quantum interference device was used in the magnetosusceptometer. Minute levels of biomarkers of early-stage neurodegeneration diseases were detectable in serum, but measuring each biomarker required [...] Read more.

An alternating-current magnetosusceptometer of antibody-functionalized magnetic nanoparticles (MNPs) was developed for immunomagnetic reduction (IMR). A high-sensitivity, high-critical-temperature superconducting quantum interference device was used in the magnetosusceptometer. Minute levels of biomarkers of early-stage neurodegeneration diseases were detectable in serum, but measuring each biomarker required approximately 4 h. Hence, an eight-channel platform was developed in this study to fit minimal screening requirements for Alzheimer’s disease. Two consistent results were measured for three biomarkers, namely Aβ40, Aβ42, and tau protein, per human specimen. This paper presents the instrument configuration as well as critical characteristics, such as the low noise level variations among channels, a high signal-to-noise ratio, and the coefficient of variation for the biomarkers’ IMR values. The instrument’s ultrahigh sensitivity levels for the three biomarkers and the substantially shorter total measurement time in comparison with the previous single- and four-channels platforms were also demonstrated in this study. Thus, the eight-channel instrument may serve as a powerful tool for clinical high-throughput screening of Alzheimer’s disease. Full article

(This article belongs to the Special Issue Magnetic Materials Based Biosensors)

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12 pages, 4034 KiB

Open AccessArticle

Accurate Determination of the Q Quality Factor in Magnetoelastic Resonant Platforms for Advanced Biological Detection

by Ana Catarina Lopes, Ariane Sagasti, Andoni Lasheras, Virginia Muto, Jon Gutiérrez, Dimitris Kouzoudis and José Manuel Barandiarán

Sensors 2018, 18(3), 887; https://doi.org/10.3390/s18030887 - 16 Mar 2018

Cited by 17 | Viewed by 4494

Abstract

The main parameters of magnetoelastic resonators in the detection of chemical (i.e., salts, gases, etc.) or biological (i.e., bacteria, phages, etc.) agents are the sensitivity

S

(or external agent change magnitude per Hz change in the resonance frequency) and the quality factor [...] Read more.

The main parameters of magnetoelastic resonators in the detection of chemical (i.e., salts, gases, etc.) or biological (i.e., bacteria, phages, etc.) agents are the sensitivity

S

(or external agent change magnitude per Hz change in the resonance frequency) and the quality factor

Q

of the resonance. We present an extensive study on the experimental determination of the

Q

factor in such magnetoelastic resonant platforms, using three different strategies: (a) analyzing the real and imaginary components of the susceptibility at resonance; (b) numerical fitting of the modulus of the susceptibility; (c) using an exact mathematical expression for the real part of the susceptibility.

Q

values obtained by the three methods are analyzed and discussed, aiming to establish the most adequate one to accurately determine the quality factor of the magnetoelastic resonance. Full article

(This article belongs to the Special Issue Magnetic Materials Based Biosensors)

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25 pages, 4316 KiB

Open AccessArticle

Mechanical, Electrical and Magnetic Properties of Ferrogels with Embedded Iron Oxide Nanoparticles Obtained by Laser Target Evaporation: Focus on Multifunctional Biosensor Applications

by Felix A. Blyakhman, Nikita A. Buznikov, Tatyana F. Sklyar, Alexander P. Safronov, Elizaveta V. Golubeva, Andrey V. Svalov, Sergey Yu. Sokolov, Grigory Yu. Melnikov, Iñaki Orue and Galina V. Kurlyandskaya

Sensors 2018, 18(3), 872; https://doi.org/10.3390/s18030872 - 15 Mar 2018

Cited by 48 | Viewed by 6832

Abstract

Hydrogels are biomimetic materials widely used in the area of biomedical engineering and biosensing. Ferrogels (FG) are magnetic composites capable of functioning as magnetic field sensitive transformers and field assisted drug deliverers. FG can be prepared by incorporating magnetic nanoparticles (MNPs) into chemically [...] Read more.

Hydrogels are biomimetic materials widely used in the area of biomedical engineering and biosensing. Ferrogels (FG) are magnetic composites capable of functioning as magnetic field sensitive transformers and field assisted drug deliverers. FG can be prepared by incorporating magnetic nanoparticles (MNPs) into chemically crosslinked hydrogels. The properties of biomimetic ferrogels for multifunctional biosensor applications can be set up by synthesis. The properties of these biomimetic ferrogels can be thoroughly controlled in a physical experiment environment which is much less demanding than biotests. Two series of ferrogels (soft and dense) based on polyacrylamide (PAAm) with different chemical network densities were synthesized by free-radical polymerization in aqueous solution with N,N’-methylene-diacrylamide as a cross-linker and maghemite Fe₂O₃ MNPs fabricated by laser target evaporation as a filler. Their mechanical, electrical and magnetic properties were comparatively analyzed. We developed a giant magnetoimpedance (MI) sensor prototype with multilayered FeNi-based sensitive elements deposited onto glass or polymer substrates adapted for FG studies. The MI measurements in the initial state and in the presence of FG with different concentrations of MNPs at a frequency range of 1–300 MHz allowed a precise characterization of the stray fields of the MNPs present in the FG. We proposed an electrodynamic model to describe the MI in multilayered film with a FG layer based on the solution of linearized Maxwell equations for the electromagnetic fields coupled with the Landau-Lifshitz equation for the magnetization dynamics. Full article

(This article belongs to the Special Issue Magnetic Materials Based Biosensors)

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24 pages, 2848 KiB

Open AccessArticle

Polyacrylamide Ferrogels with Magnetite or Strontium Hexaferrite: Next Step in the Development of Soft Biomimetic Matter for Biosensor Applications

by Alexander P. Safronov, Ekaterina A. Mikhnevich, Zahra Lotfollahi, Felix A. Blyakhman, Tatyana F. Sklyar, Aitor Larrañaga Varga, Anatoly I. Medvedev, Sergio Fernández Armas and Galina V. Kurlyandskaya

Sensors 2018, 18(1), 257; https://doi.org/10.3390/s18010257 - 16 Jan 2018

Cited by 47 | Viewed by 7042

Abstract

Magnetic biosensors are an important part of biomedical applications of magnetic materials. As the living tissue is basically a “soft matter.” this study addresses the development of ferrogels (FG) with micron sized magnetic particles of magnetite and strontium hexaferrite mimicking the living tissue. [...] Read more.

Magnetic biosensors are an important part of biomedical applications of magnetic materials. As the living tissue is basically a “soft matter.” this study addresses the development of ferrogels (FG) with micron sized magnetic particles of magnetite and strontium hexaferrite mimicking the living tissue. The basic composition of the FG comprised the polymeric network of polyacrylamide, synthesized by free radical polymerization of monomeric acrylamide (AAm) in water solution at three levels of concentration (1.1 M, 0.85 M and 0.58 M) to provide the FG with varying elasticity. To improve FG biocompatibility and to prevent the precipitation of the particles, polysaccharide thickeners—guar gum or xanthan gum were used. The content of magnetic particles in FG varied up to 5.2 wt % depending on the FG composition. The mechanical properties of FG and their deformation in a uniform magnetic field were comparatively analyzed. FG filled with strontium hexaferrite particles have larger Young’s modulus value than FG filled with magnetite particles, most likely due to the specific features of the adhesion of the network’s polymeric subchains on the surface of the particles. FG networks with xanthan are stronger and have higher modulus than the FG with guar. FG based on magnetite, contract in a magnetic field 0.42 T, whereas some FG based on strontium hexaferrite swell. Weak FG with the lowest concentration of AAm shows a much stronger response to a field, as the concentration of AAm governs the Young’s modulus of ferrogel. A small magnetic field magnetoimpedance sensor prototype with Co_68.6Fe_3.9Mo_3.0Si_12.0B_12.5 rapidly quenched amorphous ribbon based element was designed aiming to develop a sensor working with a disposable stripe sensitive element. The proposed protocol allowed measurements of the concentration dependence of magnetic particles in gels using magnetoimpedance responses in the presence of magnetite and strontium hexaferrite ferrogels with xanthan. We have discussed the importance of magnetic history for the detection process and demonstrated the importance of remnant magnetization in the case of the gels with large magnetic particles. Full article

(This article belongs to the Special Issue Magnetic Materials Based Biosensors)

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6789 KiB

Open AccessArticle

Water-Based Suspensions of Iron Oxide Nanoparticles with Electrostatic or Steric Stabilization by Chitosan: Fabrication, Characterization and Biocompatibility

by Galina V. Kurlyandskaya, Larisa S. Litvinova, Alexander P. Safronov, Valeria V. Schupletsova, Irina S. Tyukova, Olga G. Khaziakhmatova, Galina B. Slepchenko, Kristina A. Yurova, Elena G. Cherempey, Nikita A. Kulesh, Ricardo Andrade, Igor V. Beketov and Igor A. Khlusov

Sensors 2017, 17(11), 2605; https://doi.org/10.3390/s17112605 - 13 Nov 2017

Cited by 27 | Viewed by 6432

Abstract

Present day biomedical applications, including magnetic biosensing, demand better understanding of the interactions between living systems and magnetic nanoparticles (MNPs). In this work spherical MNPs of maghemite were obtained by a highly productive laser target evaporation technique. XRD analysis confirmed the inverse spinel [...] Read more.

Present day biomedical applications, including magnetic biosensing, demand better understanding of the interactions between living systems and magnetic nanoparticles (MNPs). In this work spherical MNPs of maghemite were obtained by a highly productive laser target evaporation technique. XRD analysis confirmed the inverse spinel structure of the MNPs (space group Fd-3m). The ensemble obeyed a lognormal size distribution with the median value 26.8 nm and dispersion 0.362. Stabilized water-based suspensions were fabricated using electrostatic or steric stabilization by the natural polymer chitosan. The encapsulation of the MNPs by chitosan makes them resistant to the unfavorable factors for colloidal stability typically present in physiological conditions such as pH and high ionic force. Controlled amounts of suspensions were used for in vitro experiments with human blood mononuclear leukocytes (HBMLs) in order to study their morphofunctional response. For sake of comparison the results obtained in the present study were analyzed together with our previous results of the study of similar suspensions with human mesenchymal stem cells. Suspensions with and without chitosan enhanced the secretion of cytokines by a 24-h culture of HBMLs compared to a control without MNPs. At a dose of 2.3, the MTD of chitosan promotes the stimulating effect of MNPs on cells. In the dose range of MNPs 10–1000 MTD, chitosan “inhibits” cellular secretory activity compared to MNPs without chitosan. Both suspensions did not caused cell death by necrosis, hence, the secretion of cytokines is due to the enhancement of the functional activity of HBMLs. Increased accumulation of MNP with chitosan in the cell fraction at 100 MTD for 24 h exposure, may be due to fixation of chitosan on the outer membrane of HBMLs. The discussed results can be used for an addressed design of cell delivery/removal incorporating multiple activities because of cell capability to avoid phagocytosis by immune cells. They are also promising for the field of biosensor development for the detection of magnetic labels. Full article

(This article belongs to the Special Issue Magnetic Materials Based Biosensors)

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2130 KiB

Open AccessArticle

Characterizations of Anti-Alpha-Fetoprotein-Conjugated Magnetic Nanoparticles Associated with Alpha-Fetoprotein for Biomedical Applications

by Shu-Hsien Liao, Han-Sheng Huang, Jen-Jie Chieh, Yu-Kai Su, Yuan-Fu Tong and Kai-Wen Huang

Sensors 2017, 17(9), 2018; https://doi.org/10.3390/s17092018 - 3 Sep 2017

Cited by 4 | Viewed by 4555

Abstract

In this work, we report characterizations of biofunctionalized magnetic nanoparticles (BMNPs) associated with alpha-fetoprotein (AFP) for biomedical applications. The example BMNP in this study is anti-alpha-fetoprotein (anti-AFP) conjugated onto dextran-coated Fe₃O₄ labeled as Fe₃O₄-anti-AFP, and the [...] Read more.

In this work, we report characterizations of biofunctionalized magnetic nanoparticles (BMNPs) associated with alpha-fetoprotein (AFP) for biomedical applications. The example BMNP in this study is anti-alpha-fetoprotein (anti-AFP) conjugated onto dextran-coated Fe₃O₄ labeled as Fe₃O₄-anti-AFP, and the target is AFP. We characterize magnetic properties, such as increments of magnetization ΔM_H and effective relaxation time Δτ_eff in the reaction process. It is found that both ΔM_H and Δτ_eff are enhanced when the concentration of AFP, Ф_AFP, increases. The enhancements are due to magnetic interactions among BMNPs in magnetic clusters, which contribute extra M_H after the association with M_H and in turn enhance τ_eff. The screening of patients carrying hepatocellular carcinoma (HCC) is verified via ΔM_H/M_H. The proposed method can be applied to detect a wide variety of analytes. The scaling characteristics of ΔM_H/M_H show the potential to develop a vibrating sample magnetometer system with low field strength for clinic applications. Full article

(This article belongs to the Special Issue Magnetic Materials Based Biosensors)

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Review

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13 pages, 4570 KiB

Open AccessFeature PaperReview

Galfenol Thin Films and Nanowires

by Bethanie J. H. Stadler, Madhukar Reddy, Rajneeta Basantkumar, Patrick McGary, Eliot Estrine, Xiaobo Huang, Sang Yeob Sung, Liwen Tan, Jia Zou, Mazin Maqableh, Daniel Shore, Thomas Gage, Joseph Um, Matthew Hein and Anirudh Sharma

Sensors 2018, 18(8), 2643; https://doi.org/10.3390/s18082643 - 12 Aug 2018

Cited by 14 | Viewed by 5041

Abstract

Galfenol (Fe_1−xGa_x, 10 < x < 40) may be the only smart material that can be made by electrochemical deposition which enables thick film and nanowire structures. This article reviews the deposition, characterization, and applications of Galfenol thin films [...] Read more.

Galfenol (Fe_1−xGa_x, 10 < x < 40) may be the only smart material that can be made by electrochemical deposition which enables thick film and nanowire structures. This article reviews the deposition, characterization, and applications of Galfenol thin films and nanowires. Galfenol films have been made by sputter deposition as well as by electrochemical deposition, which can be difficult due to the insolubility of gallium. However, a stable process has been developed, using citrate complexing, a rotating disk electrode, Cu seed layers, and pulsed deposition. Galfenol thin films and nanowires have been characterized for crystal structures and magnetostriction both by our group and by collaborators. Films and nanowires have been shown to be largely polycrystalline, with magnetostrictions that are on the same order of magnitude as textured bulk Galfenol. Electrodeposited Galfenol films were made with epitaxial texture on GaAs. Galfenol nanowires have been made by electrodeposition into anodic aluminum oxide templates using similar parameters defined for films. Segmented nanowires of Galfenol/Cu have been made to provide engineered magnetic properties. Applications of Galfenol and other magnetic nanowires include microfluidic sensors, magnetic separation, cellular radio-frequency identification (RFID) tags, magnetic resonance imaging (MRI) contrast, and hyperthermia. Full article

(This article belongs to the Special Issue Magnetic Materials Based Biosensors)

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22 pages, 17903 KiB

Open AccessReview

Aptamer-Modified Magnetic Beads in Biosensing

by Harshvardhan Modh, Thomas Scheper and Johanna-Gabriela Walter

Sensors 2018, 18(4), 1041; https://doi.org/10.3390/s18041041 - 30 Mar 2018

Cited by 52 | Viewed by 13288

Abstract

Magnetic beads (MBs) are versatile tools for the purification, detection, and quantitative analysis of analytes from complex matrices. The superparamagnetic property of magnetic beads qualifies them for various analytical applications. To provide specificity, MBs can be decorated with ligands like aptamers, antibodies and [...] Read more.

Magnetic beads (MBs) are versatile tools for the purification, detection, and quantitative analysis of analytes from complex matrices. The superparamagnetic property of magnetic beads qualifies them for various analytical applications. To provide specificity, MBs can be decorated with ligands like aptamers, antibodies and peptides. In this context, aptamers are emerging as particular promising ligands due to a number of advantages. Most importantly, the chemical synthesis of aptamers enables straightforward and controlled chemical modification with linker molecules and dyes. Moreover, aptamers facilitate novel sensing strategies based on their oligonucleotide nature that cannot be realized with conventional peptide-based ligands. Due to these benefits, the combination of aptamers and MBs was already used in various analytical applications which are summarized in this article. Full article

(This article belongs to the Special Issue Magnetic Materials Based Biosensors)

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