Quantification of biological or biochemical processes are of utmost importance for medical, biological and biotechnological applications. However, converting the biological information to an easily processed electronic signal is challenging due to the complexity of connecting an electronic device directly to a biological environment. Electrochemical biosensors provide an attractive means to analyze the content of a biological sample due to the direct conversion of a biological event to an electronic signal. Over the past decades several sensing concepts and related devices have been developed. In this review, the most common traditional techniques, such as cyclic voltammetry, chronoamperometry, chronopotentiometry, impedance spectroscopy, and various field-effect transistor based methods are presented along with selected promising novel approaches, such as nanowire or magnetic nanoparticle-based biosensing. Additional measurement techniques, which have been shown useful in combination with electrochemical detection, are also summarized, such as the electrochemical versions of surface plasmon resonance, optical waveguide lightmode spectroscopy, ellipsometry, quartz crystal microbalance, and scanning probe microscopy. The signal transduction and the general performance of electrochemical sensors are often determined by the surface architectures that connect the sensing element to the biological sample at the nanometer scale. The most common surface modification techniques, the various electrochemical transduction mechanisms, and the choice of the recognition receptor molecules all influence the ultimate sensitivity of the sensor. New nanotechnology-based approaches, such as the use of engineered ion-channels in lipid bilayers, the encapsulation of enzymes into vesicles, polymersomes, or polyelectrolyte capsules provide additional possibilities for signal amplification. In particular, this review highlights the importance of the precise control over the delicate interplay between surface nano-architectures, surface functionalization and the chosen sensor transducer principle, as well as the usefulness of complementary characterization tools to interpret and to optimize the sensor response.

/pdf/electrochemical-biosensors-sensor-principles-and-5i1lr0kwi6.pdf

Electrochemical Biosensors - Sensor Principles and Architectures

Background: The difficulty of directly measuring cellular dose is a significant obstacle to application of target tissue dosimetry for nanoparticle and microparticle toxicity assessment, particularly for in vitro systems. As a consequence, the target tissue paradigm for dosimetry and hazard assessment of nanoparticles has largely been ignored in favor of using metrics of exposure (e.g. μg particle/mL culture medium, particle surface area/mL, particle number/mL). We have developed a computational model of solution particokinetics (sedimentation, diffusion) and dosimetry for non-interacting spherical particles and their agglomerates in monolayer cell culture systems. Particle transport to cells is calculated by simultaneous solution of Stokes Law (sedimentation) and the Stokes-Einstein equation (diffusion). Results: The In vitro Sedimentation, Diffusion and Dosimetry model (ISDD) was tested against measured transport rates or cellular doses for multiple sizes of polystyrene spheres (20-1100 nm), 35 nm amorphous silica, and large agglomerates of 30 nm iron oxide particles. Overall, without adjusting any parameters, model predicted cellular doses were in close agreement with the experimental data, differing from as little as 5% to as much as three-fold, but in most cases approximately two-fold, within the limits of the accuracy of the measurement systems. Applying the model, we generalize the effects of particle size, particle density, agglomeration state and agglomerate characteristics on target cell dosimetry in vitro. Conclusions: Our results confirm our hypothesis that for liquid-based in vitro systems, the dose-rates and target cell doses for all particles are not equal; they can vary significantly, in direct contrast to the assumption of doseequivalency implicit in the use of mass-based media concentrations as metrics of exposure for dose-response assessment. The difference between equivalent nominal media concentration exposures on a μg/mL basis and target cell doses on a particle surface area or number basis can be as high as three to six orders of magnitude. As a consequence, in vitro hazard assessments utilizing mass-based exposure metrics have inherently high errors where particle number or surface areas target cells doses are believed to drive response. The gold standard for particle dosimetry for in vitro nanotoxicology studies should be direct experimental measurement of the cellular content of the studied particle. However, where such measurements are impractical, unfeasible, and before such measurements become common, particle dosimetry models such as ISDD provide a valuable, immediately useful alternative, and eventually, an adjunct to such measurements.

/pdf/isdd-a-computational-model-of-particle-sedimentation-25gpkr9e4j.pdf

ISDD: A Computational Model of Particle Sedimentation, Diffusion and Target Cell Dosimetry for In Vitro Toxicity Studies

Nanomaterials, in addition to their small size, possess unique physicochemical properties that differ from bulk materials, making them ideal for a host of novel applications. Magnetic nanoparticles (MNPs) are one important class of nanomaterials that have been widely studied for their potential applications in nanomedicine. Due to the fact that MNPs can be detected and manipulated by remote magnetic fields, it opens a wide opportunity for them to be used in vivo. Nowadays, MNPs have been used for diverse applications including magnetic biosensing (diagnostics), magnetic imaging, magnetic separation, drug and gene delivery, and hyperthermia therapy, etc. Specifically, we reviewed some emerging techniques in magnetic diagnostics such as magnetoresistive (MR) and micro-Hall (μHall) biosensors, as well as the magnetic particle spectroscopy, magnetic relaxation switching and surface enhanced Raman spectroscopy (SERS)-based bioassays. Recent advances in applying MNPs as contrast agents in magnetic resonance imaging and as tracer materials in magnetic particle imaging are reviewed. In addition, the development of high magnetic moment MNPs with proper surface functionalization has progressed exponentially over the past decade. To this end, different MNP synthesis approaches and surface coating strategies are reviewed and the biocompatibility and toxicity of surface functionalized MNP nanocomposites are also discussed. Herein, we are aiming to provide a comprehensive assessment of the state-of-the-art biological and biomedical applications of MNPs. This review is not only to provide in-depth insights into the different synthesis, biofunctionalization, biosensing, imaging, and therapy methods but also to give an overview of limitations and possibilities of each technology.

https://iopscience.iop.org/article/10.1088/1361-6528/ab4241/pdf

Magnetic nanoparticles in nanomedicine: a review of recent advances.

Antibody-based sensors permit the rapid and sensitive analysis of a range of pathogens and associated toxins. A critical assessment of the implementation of such formats is provided, with reference to their principles, problems and potential for 'on-site' analysis. Particular emphasis is placed on the detection of foodborne bacterial pathogens, such as Escherichia coli and Listeria monocytogenes, and additional examples relating to the monitoring of fungal pathogens, viruses, mycotoxins, marine toxins and parasites are also provided.

https://www.mdpi.com/1424-8220/9/6/4407/pdf

Antibody-Based Sensors: Principles, Problems and Potential for Detection of Pathogens and Associated Toxins

The cardiovascular disease (CVD) is considered as a major threat to global health. Therefore, there is a growing demand for a range of portable, rapid and low cost biosensing devices for the detection of CVD. Biosensors can play an important role in the early diagnosis of CVD without having to rely on hospital visits where expensive and time-consuming laboratory tests are recommended. Over the last decade, many biosensors have been developed to detect a wide range of cardiac marker to reduce the costs for healthcare. One of the major challenges is to find a way of predicting the risk that an individual can suffer from CVD. There has been considerable interest in finding diagnostic and prognostic biomarkers that can be detected in blood and predict CVD risk. Of these, C-reactive protein (CRP) is the best known biomarker followed by cardiac troponin I or T (cTnI/T), myoglobin, lipoprotein-associated phospholipase A(2), interlukin-6 (IL-6), interlukin-1 (IL-1), low-density lipoprotein (LDL), myeloperoxidase (MPO) and tumor necrosis factor alpha (TNF-α) has been used to predict cardiovascular events. This review provides an overview of the available biosensor platforms for the detection of various CVD markers and considerations of future prospects for the technology are addressed.

/pdf/biosensors-for-cardiac-biomarkers-detection-a-review-4qnv27zln9.pdf

Biosensors for cardiac biomarkers detection: A review

Magnetic biosensor for the detection of Yersinia pestis.

Francisella tularensis detection using magnetic labels and a magnetic biosensor based on frequency mixing

The invention relates to a method for selectively detecting and/or quantifying superparamagnetic and/or ferromagnetic particles on analytes The method is characterized in that a frequency component of magnetic fields (15, 18), which is generated due to the non-linearity of the magnetization characteristic curve of the particles, is measured at a mixing frequency A device for selectively detecting and/or quantifying superparamagnetic and/or ferromagnetic particles on analytes comprises: a container (12) that contains particles, which are to be detected and/or quantified, on analytes; at least one oscillator (13, 16; 25) for generating frequencies of alternating magnetic fields (15, 18); at least one field generator (14, 17) for subjecting the analytes to alternating magnetic fields (15, 18); a magnetic field sensor (20) for measuring a response magnetic field (19) of the particles, and; at least one phase-sensitive detector (21, 23) These elements are configured in such a manner as to enable a frequency component of the magnetic fields (15, 18), which is generated due to the non-linearity of the magnetization characteristic curve of the particles, to be measured at a mixing frequency

Method and device for selectively detecting ferromagnetic or superparamagnetic particles.

Die
Erfindung beschreibt ein Verfahren zum selektiven Nachweis und/oder
zur Quantifizierung superparamagnetischer und/oder ferromagnetischer Partikel
an Analyten. Das Verfahren ist dadurch gekennzeichnet, dass
eine aufgrund der Nichtlinearitat
der Magnetisierungskennlinie der Partikel erzeugte Frequenz-Komponente
von Magnetfeldern (15, 18) bei einer Mischfrequenz gemessen wird. Eine
Vorrichtung zum selektiven Nachweis und/oder zur Quantifizierung
superparamagnetischer und/oder ferromagnetischer Partikel an Analyten
umfasst: - einen Behalter
(12) mit nachzuweisenden und/oder zu quantifizierenden Partikeln
am Analyten, - mindestens einen Oszillator (13, 16; 25), zur
Erzeugung von Frequenzen von Wechsel-Magnetfeldern (15, 18), -
mindestens einen Feldgenerator (14, 17) zur Beaufschlagung des Analyten
mit Wechsel-Magnetfeldern (15, 18), - einen Magnetfeldsensor
(20) zur Messung eines Antwort-Magnetfeldes (19) der Partikel, -
mindestens einen phasenempfindlichen Detektor (21, 23), wobei
die Bauteile so konfiguriert sind, dass eine aufgrund der Nichtlinearitat der Magnetisierungskennlinie
der Partikel erzeugte Frequenz-Komponente der Magnetfelder (15, 18)
bei einer Mischfrequenz gemessen wird.

Verfahren und Vorrichtung zum selektiven Nachweis magnetischer Partikel

Ein Verfahren zum selektiven Nachweis und/oder zur Quantifizierung superparamagnetischer und/oder ferromagnetischer Partikel an Analyten. Das Verfahren ist dadurch gekennzeichnet, dass eine aufgrund der Nichtlinearitat der Magnetisierungskennlinie der Partikel erzeugte Frequenz-Komponente von Magnetfeldern (15, 18) bei einer Mischfrequenz gemessen wird. Eine Vorrichtung zum selektiven Nachweis und/oder zur Quantifizierung superparamagnetischer und/oder ferromagnetischer Partikel an Analyten umfasst: einen Behalter (12) mit nachzuweisendem und/oder zu quantifizierenden Partikeln am Analyten, mindestens einen Oszillator (13, 16; 25), zur Erzeugung von Frequenzen von Wechsel-Magnetfeldern (15, 18), mindestens einen Feldgenerator (14, 17) zur Beaufschlagung des Analyten mit Wechsel-Magnetfeldern (15, 18) , einen Magnetfeldsensor (20), zur Messung eines Antwort-Magnetfeldes (19) der Partikel, mindestens einen phasenempfindlichen Detektor (21, 23), wobei die Bauteile so konfiguriert sind, dass eine aufgrund der Nichtlinearitat der Magnetisierungskennlinie der Partikel erzeugte Frequenz-Komponente der Magnetfelder (15, 18) bei einer Mischfrequenz gemessen wird.

Verfahren und vorrichtung zum selektiven nachweis ferromagnetischer oder superparamagnetischer partikel

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