Magneto-stimulated hydrodynamic control of electrocatalytic and bioelectrocatalytic processes

Magnetic rotation of redox-functionalized magnetite particles leads to enhanced electrocatalysis and bioelectrocatalysis.     

Magnetic control of bioelectrocatalytic processes based on assembled iron oxide particles

A facile magnetic control system was designed in bioelectrocatalytic process based on functionalized iron oxide particles. The iron oxide particles were modified with glucose oxidase, and ferrocene dicarboxylic acid was used as electron transfer mediator. Functionalized iron oxide particles can assemble along the direction of applied magnetic field, and the directional dependence of the assembled iron oxide particles can be utilized for device purposes. We report here how such functionalized magnetic particles are used to modulate the bioelectrocatalytic signal by changing the orientation of the applied magnetic field.     

Magneto-switchable electrocatalytic and bioelectrocatalytic transformations

Magnetic switching of redox reactions and bioelectrocatalytic transformations is accomplished in the presence of relay-functionalized magnetite particles (Fe(3)O(4)). The electrochemistry of a naphthoquinone (1), pyrroloquinoline quinone (2; PQQ), microperoxidase-11 (3), a ferrocene derivative (4) and a bipyridinium derivative (5), functionalized magnetic particles, is switched "ON" and "OFF" by an external magnet upon the attraction of the magnetic particles to an electrode or their retraction from the electrode, respectively. The magneto-switchable activation and deactivation of the electrochemical oxidation of the ferrocene-functionalized magnetic particles and the electrochemical reduction of the bipyridinium-functionalized magnetic particles are used for the triggering of mediated bioelectrocatalytic oxidation of glucose, in the presence of glucose oxidase (GOx), and bioelectrocatalytic reduction of nitrate (NO(3) (-)), in the presence of nitrate reductase (NR), respectively. Magnetic particles functionalized with a PQQ-NAD(+) dyad are used for the magnetic switching of the bioelectrocatalytic oxidation of lactate in the presence of lactate dehydrogenase (LDH). The coupling of these particles with a ferrocene-monolayer-functionalized electrode allows the dual and selective sensing of lactate and glucose in the presence of LDH and GOx, respectively, by using an external magnet to switch the detection mode.     

Protein‐Functionalized Synthetic Antiferromagnetic Nanoparticles for Biomolecule Detection and Magnetic Manipulation

Direct protein functionalization provides synthetic antiferromagnetic nanoparticles with high chemical specificity and multifunctionality. These nanoparticle–protein conjugates function as improved magnetic labels for biological detection experiments, and exhibit tunable responses to a small external magnetic field gradient, thus allowing the observation of distinctive single nanoparticle motion.

     

Remote Control of T Cell Activation Using Magnetic Janus Particles

We report a strategy for using magnetic Janus microparticles to control the stimulation of T cell signaling with single‐cell precision. To achieve this, we designed Janus particles that are magnetically responsive on one hemisphere and stimulatory to T cells on the other side. By manipulating the rotation and locomotion of Janus particles under an external magnetic field, we could control the orientation of the particle–cell recognition and thereby the initiation of T cell activation. This study demonstrates a step towards employing anisotropic material properties of Janus particles to control single‐cell activities without the need of complex magnetic manipulation devices.     

Harnessing Effective Molarity to Design an Electrochemical DNA‐based Platform for Clinically Relevant Antibody Detection

Easy‐to‐use platforms for rapid antibody detection are likely to improve molecular diagnostics and immunotherapy monitoring. However, current technologies require multi‐step, time‐consuming procedures that limit their applicability in these fields. Herein, we demonstrate effective molarity‐driven electrochemical DNA‐based detection of target antibodies. We show a highly selective, signal‐on DNA‐based sensor that takes advantage of antibody‐binding‐induced increase of local concentration to detect clinically relevant antibodies in blood serum. The sensing platform is modular, rapid, and versatile and allows the detection of both IgG and IgE antibodies. We also demonstrate the possible use of this strategy for the monitoring of therapeutic monoclonal antibodies in body fluids. Our approach highlights the potential of harnessing effective molarity for the design of electrochemical sensing strategies.     

Harnessing Effective Molarity to Design an Electrochemical DNA-based Platform for Clinically Relevant Antibody Detection

Easy-to-use platforms for rapid antibody detection are likely to improve molecular diagnostics and immunotherapy monitoring. However, current technologies require multi-step, time-consuming procedures that limit their applicability in these fields. Herein, we demonstrate effective molarity-driven electrochemical DNA-based detection of target antibodies. We show a highly selective, signal-on DNA-based sensor that takes advantage of antibody-binding-induced increase of local concentration to detect clinically relevant antibodies in blood serum. The sensing platform is modular, rapid, and versatile and allows the detection of both IgG and IgE antibodies. We also demonstrate the possible use of this strategy for the monitoring of therapeutic monoclonal antibodies in body fluids. Our approach highlights the potential of harnessing effective molarity for the design of electrochemical sensing strategies.     

Magnetic nano- and microparticles in biotechnology

Both synthetic and biologically produced magnetic nano- and microparticles exhibit several types of responses to external magnetic field which have been already employed in various areas of biosciences, biotechnology, medicine, environmental technology, etc. This short review shows selected important biotechnological applications of magnetic particles, and the biological processes leading to biogenic magnetic particles formation. Presented at the 1st Nanomaterials and Nanotechnology Meeting, Nano Ostrava, Ostrava, Czech Republic, 1–4 September 2008.     

Electrochemistry in solids prepared by sol-gel processes

Sol-gel chemistry provides a route to preparing inorganic polymers with ionically conducting properties by room temperature synthetic routes. The products, which are rigid solids, are well-suited as media for conventional electrochemical techniques such as cyclic voltammetry. This property, when combined with their ability to host a wide variety of species, has allowed development of a variety of devices of interest in electrochemistry and analytical chemistry. Examples include cathodes for fuels cells, electrochromic devices, biosensors, and amperometric sensors for analytes in the gas phase. In this review, the emphasis will be on reported applications to analytical chemistry; however, studies on the general properties of these materials and on their use in electrochemical science also will be summarized because they may provide the basis for further development of sensors.     

磁场对超细镍粉的磁性能及电磁屏蔽性能的影响

分别在水和乙二醇溶液中,于搅拌条件下采用液相还原法制备超细镍粉,研究反应过程中外加磁场对产物形貌及性能的影响。结果表明,水中得到的产品为刺球状颗粒,外加磁场对产物的形貌影响不大;乙二醇中得到类球形颗粒,加磁场后得到短链状结构。外加磁场使超细镍粉的饱和磁化强度值降低而矫顽力值升高。将水体系中得到的超细镍粉作为导电填料制备电磁屏蔽涂料,结果发现外加磁场条件下得到的超细镍粉/树脂复合涂料在130 MHz～1.5 GHz频段内具有更好的电磁屏蔽性能。     

Physical Properties of Elongated Magnetic Particles: Magnetization and Friction Coefficient Anisotropies

Anisotropy counts: A brief review of the main physical properties of elongated magnetic particles (EMPs) is presented. The most important characteristic of an EMP is the additional contribution of shape anisotropy to the total anisotropy energy of the particle, when compared to spherical magnetic particles. The electron micrograph shows Ni‐ferrite microrods fabricated by the authors.

     

Extraction of Rutin and Rhoifolin by Inorganic Borate Functionalized Magnetic Particles

We demonstrate a facile approach for smart time‐saving extraction of active components of rutin and rhoifolin by a new kind of magnetic particles (MPs). The inorganic borate functionalized magnetic particles are quasi‐spherical with an average diameter of 200–220 nm. The MPs were characterized by scanning electron microscopy and X‐ray diffraction techniques. The inorganic boron content in MPs was confirmed by electron‐dispersive X‐ray spectroscopy. The extraction and release efficiency of MPs were investigated. The smart borate‐decorated magnetic particles show a specific extraction towards the active components containing cis‐1,2 diol moieties. Rutin and rhoifolin were extracted at 16.55 and 22.49 mg/g, respectively. The recycling test shows that MPs can be reused and maintain a significant efficiency for seven cycles. Hence, a novel structured and reusable magnetic nanomaterial for extracting rutin and rhoifolin was developed. This strategy of specific extraction will be an important method to obtain the active components with some structure features through designing various structured particles.     

电化学DNA生物传感器*

对特异DNA序列的检测在基因相关疾病的诊断、军事反恐和环境监测等方面均具有非常重要的意义,DNA传感器的研究就是为了满足对特异DNA序列的快速、便捷、高灵敏度和高选择性检测的需要。近年来涌现出了多种传感策略,根据检测方法的不同可以大致分为光学传感器、电化学传感器、声学传感器等。由于电化学检测方法本身所具有的灵敏、快速、低成本和低能耗等特点,电化学DNA传感器已成为一个非常活跃的研究领域并在近几年中得到了快速发展。本文概括了近年来在DNA传感器的重要分支——电化学DNA传感器领域内的一些重要进展,主要包括DNA探针在传感界面上的固定方法和各种电化学DNA杂交信号的检测方法。     

Magnetic Resonance Imaging of Electrochemical Cells Containing Bulk Metal

The development of improved energy‐storage devices, as well as corrosion prevention and metal‐electrofinishing technologies, requires knowledge of local composition and transport behaviour in electrolytes near bulk metals, in situ and in real time. It remains a challenge to acquire such data and new analytical methods are required. Recent work shows that magnetic resonance imaging (MRI) is able to map concentration gradients and visualise electrochemical processes in electrochemical cells containing bulk metals. This recent work, along with the challenges, and solutions, associated with MRI of these electrochemical cells are reviewed.