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The development of wearable devices provides approaches for the realization of self-health care. Easily carried wearable devices allow individual health monitoring at any place whenever necessary. There are various interesting monitoring targets, including body motion, organ pressure, and biomarkers. An efficient use of space in one small device is a promising resolution to increase the functions of wearable devices. Through integration of a microfluidic system into wearable devices, embedding complicated structures in one design becomes possible and can enable multifunction analyses within a limited device volume. This article reviews the reported microfluidic wearable devices, introduces applications to different biofluids, discusses characteristics of the design strategies and sensing principles, and highlights the attractive configurations of each device. This review seeks to provide a detailed summary of recent advanced microfluidic wearable devices. The overview of advanced key components is the basis for the development of future microfluidic wearable devices. Expected final online publication date for the Annual Review of Analytical Chemistry, Volume 16 is June 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Droplet-based transport driven by surface tension has been explored as an automated pumping source for several biomedical applications. This paper presented a simple and fast superhydrophobic modify and patterning approach to fabricate various open-surface platforms to manipulate droplets to achieve transport, mixing, concentration, and rebounding control. Several commercial reagents were tested in our approach, and the Glaco reagent was selected to create a superhydrophobic layer; laser cutters are utilized to scan on these superhydrophobic surface to create gradient hydrophilic micro-patterns. Implementing back-and-forth vibrations on the predetermined parallel patterns, droplets can be transported and mixed successfully. Colorimetry of horseradish peroxidase (HRP) mixing with substrates also reduced the reaction time by more than 5-times with the help of superhydrophobic patterned chips. Besides, patterned superhydrophobic chips can significantly improve the sensitivity of colorimetric glucose-sensing by more than 10 times. Moreover, all bioassays were distributed homogeneously within the region of hydrophilic micropatterns without the coffee-ring effect. In addition, to discuss further applications of the surface wettability, the way of controlling the droplet impacting and rebounding phenomenon was also demonstrated. This work reports a rapid approach to modify and pattering superhydrophobic films to perform droplet-based manipulations with a lower technical barrier, higher efficiency, and easier operation. It holds the potential to broaden the applications of open microfluidics in the future.

In this study, a novel gradient grating period guided-mode resonance (GGP-GMR) biosensor is proposed, and albumin was successfully detected as a test model. The GGP-GMR sensor exhibits a gradient resonant wavelength along the device. At a fixed incident wavelength, light resonates at a specific period such that the light is reflected at this period (or resonant period) and transmitted to other periods. Thus, for a charge-coupled device under the GGP-GMR sensor, a dip-like intensity distribution was measured with a specific pixel of minimum intensity corresponding to the resonant period. The variation in sample concentrations caused changes in the refractive index (RI) on the sensor surface, which induced a shift in the resonant period and in the pixel corresponding to the minimum intensity. A GGP-GMR sensor can achieve a limit of detection of $8.58\times 10^{{-4}}$ RIU within a detection range of sucrose solutions of 0%–60% concentrations that corresponds to the RI from 1.333 to 1.442. In a buffer solution, albumin was successfully detected to measure the clinically relevant concentration. The simple design and easy fabrication of the GGP-GMR sensor combined with its simple readout and optical path design facilitates system miniaturization for handheld devices and its integration with smartphones, which could be beneficial for future point-of-care applications.

Enzyme-linked immunosorbent assays (ELISAs) are tests that uses antibody recognition and enzyme catalytic activity to identify a substance, and they have been widely used as a diagnostic tool in the clinic.

Lung cancer is one of the leading causes of death worldwide. Fifteen percent of lung cancer patients will present with malignant pleural effusion initially, and up to 50% will have malignant pleural effusion throughout the course of the disease. In this study, we developed a spiral microfluidic device that can rapidly isolate cancer cells and improve their purity through fluid dynamics. This label-free, high-throughput device continuously isolates cancer cells and other unrelated molecules from pleural effusion. Most of the background cells that affect interpretation are flushed to outlets 1 to 3, and cancer cells are hydrodynamically concentrated to outlet 4, with 90% of lung cancer cells flowing to this outlet. After processing, the purity of cancer cells identified in pleural effusion by CD45 and epithelial cell adhesion molecule (EpCAM) antibodies in flow cytometry will be increased by 6 to 24 times. The microfluidic device presented here has the advantages of rapid processing and low cost, which are conducive to rapid and accurate clinical diagnosis.

Electrochemical biosensors have been applied in a broad range of clinical applications for pathogen biomarker detection and medical applications and diagnosis due to the sensitivity of electrochemical methods and the bioselectivity of the components. The complexity of clinical conditions with various biofoulants (proteins, cells, polysaccharides and lipids) severely influences the reliability and stability of sensors for direct detection or immersion under changing conditions. Therefore, designing an antifouling sensing platform that can effectively reduce undesired binding to maintain biosensor performance in optimized analysis is necessary. For this purpose, the fundamental mechanisms of fouling materials and commonly used biocompatible antifouling components have been discussed, and the relevant effective modification strategies are introduced in this review. Recent advances in these strategies are demonstrated in examples with analysis of essential modification methods for reliable sensing in non-specific binding solutions or complex biofluids. The challenges and future perspectives of modification strategies for current clinical application are also discussed in this review.

Proper orientation of probes and the binding capacity of surfaces will determine the performance of bio-applications. It has been reported that immobilizing through bio-/chemical affinity is an efficient but gentle strategy to solve the above-mentioned issue. Herein, we introduce a total self-assembly approach

Alzheimer's disease (AD) is one of the important neurodegenerative diseases, in the modern aging society, it has become an issue people need to work on. Of the pathogenic factor which leads to AD, beta-amyloid (Aβ) is the most important one. It can form the senile plaque which aggregates in the neuron and interrupts the signal transmission. This research is based on the electrochemical system and screen-printed carbon electrode (SPCE) incorporated with pretreatment, electrodeposition, electrochemical impedance spectroscopy (EIS), antibody, and blocking agent. This immunosensor is applied to detect the different concentrations of Aβ. The standard curve between electrical impedance and concentration of Aβ is calculated. The specificity of the immunosensor is tested. This survey optimizes the electrodeposition condition for 4-aminobenzoic acid (4-ABA) and the parameter for antibody and blocking agents. This study fabricates a more dense, uniform, and stable film of 4-ABA. This sensor presents a range of detection from 1 fg/ml to 100 pg/ml and a limit of detection to 3.84 fg/ml. This sensor can identify the isoform of Aβ. This research shortens the fabricating time to 3.5 h. This study fabricates a label-free and low-cost immunosensor for Aβ with a short fabricating time, high stability, wide range of detection, low limit of detection, and good specificity. The impedance of the carbon printed electrodes is very high and is always measured by its current but this study provides a fabrication technique for high-efficiency carbon printed electrodes for electrochemical impedance spectroscopy sensing.

Plasma-based Al2O3 atomic layer etching (pALE) has a reaction mechanism similar to thermal Al2O3 ALE (tALE). The main difference between the two methods is that pALE uses plasma instead of HF in tALE to fluorinate Al2O3 to AlF3. In this study, the CF4 plasma source commonly used for dry etching is combined with a self-developed low-ion-bombardment remote Al2O3 plasma-based ALE system to obtain Al2O3 plasma fluorination conditions, and then the AlCl(CH3)2 (dimethylaluminum chloride) precursor is used to develop the pALE Al2O3 process. In addition to using x-ray photoelectron spectroscopy to investigate ideal fluorination conditions of CF4 plasma for Al2O3 films and establishing the linear etching rate curves of pALE at different process temperatures (250–400 °C), we used atomic force microscopy to analyze the surface morphology of the Al2O3 films after dry etching and pALE. We showed that pALE can smooth Al2O3 films with a root mean square surface roughness of 1.396–0.655 nm and used anodic aluminum oxide substrates with nanotrench structures to demonstrate that pALE can improve the surface roughness of nonplanar structures.

Open-surface microfluidics is promising in terms of enabling economical and rapid biochemical analysis for addressing challenges associated with medical diagnosis and food safety. To this end, we present a simple and economical approach to develop an open-surface microfluidic platform suitable for facile liquid transport and mixing. Customizable patterns with tailored wettability are deposited using a plasma-assisted deposition technique under atmospheric pressure. The flow of the dispensed liquid is driven by gravity, and the tilting angle of the device determines the extent of mixing. First, a hexamethyldisiloxane film was deposited to create hydrophobic patterns on glass, and then, hydrophilic acrylic acid was deposited by a patterned cardboard mask to construct a channel suitable for forming channels to transport aqueous liquids without the need of an external energy input; the liquid can be confined to designated pathways. Several designs including Y-junctions, serpentine-shaped patterns, splitting channels, and concentration gradient generation patterns are presented. The proposed method can spatially pattern a surface with a hydrophobic/hydrophilic area, which can function as a microfluidic channel, and the surface can be applied in microfluidic devices with other types of substrates.

Peripheral blood lymphocytes (PBLs) are mature lymphocytes that circulate in the blood rather than being localized to organs. A reliable label-free collection approach that can viably and appropriately isolate PBLs to establish in vitro culture systems is crucial for basic research and clinical requirements. However, isolation of PBLs from whole blood is difficult, and so the development of a rapid and safe method to perform this task is required. Microfluidic technology offers opportunities that challenge the performance of macroscale methods. In this study, we proposed a simple spiral microfluidic chip for efficient and high-throughput isolation of lymphocytes from a sample with prelysed RBCs. This spiral microfluidic platform does not rely on antibodies or biological markers for labeling cells of interest while isolating lymphocytes but rather enriches B and T lymphocytes through the different physical properties that are intrinsic to lymphocytes and other blood cells. The device was used to achieve high-throughput (~1.3 × 105 cells/min) separation of lymphocytes with high viability (>95%). Compared with previous approaches, our device provided rapid, label-free, high-throughput, and safe lymphocyte separation.

In this study, the surface properties of iron microparticles were modified for the manipulation of liquid droplets using atmospheric pressure plasma jets. These modified hydrophobic iron microparticles were prepared by synthesizing fluorinated silica nanocomposites on the surfaces of iron microparticles under atmospheric pressure plasma. The compositions of the silica nanocomposites were controlled by the deposition of hexamethyldisiloxane and fluoroalkylsilane precursors. The fluorinated silica nanocomposites were then used with iron microparticles to prepare magnetic liquid marbles. The contact angles of the iron microparticles and the fluorinated silica nanoparticle coating on the glass surface were both 154°, which indicated that the surfaces of these particles were superhydrophobic. Higher hexamethyldisiloxane precursor flow rates produced more silica nanocomposites and resulted in greater roughness and larger contact angles. Changes in surface roughness were characterized by atomic force microscopy. X-ray photoelectron spectroscopy showed that C–F bonds were present on the modified glass surface. The presented approach allows rapid and highly efficient modification of uneven surfaces and can therefore be employed to render hydrophilic, superhydrophobic, and oleophilic surfaces. Moreover, the described hydrophobic iron microparticles can be used for the controlled magnetic manipulation of water droplets and oil–water separation.

A biosensor is generally defined as an analytical device, which converts the biochemical responses into the quantifiable electronic signals. Its extensive utilities in medical diagnosis, toxicity testing, chemical analysis, food industry, and many other areas for quantitative assessments has appeared. Quartz crystal microbalance and field-effect transistor based devices have been demonstrated to possess exceptional characteristics and outstanding performance while conjugated with the advanced nanotechnology. However, both devices still have to face the nonspecific binding issue, which is a headache for researchers on all biosensor platforms. In our research, we have efficaciously reduce 95% nonspecific binding via immobilize the zwitterionic layer on the surface of the chip. Moreover, we integrate microfluidics, nanoparticles, rapid surface modification on several bio-sensing platforms to efficiently pretreat specimens and detect target biomolecules. In addition, a series advanced microfluidic ships are designed for lymphocyte isolation, active sperm sorting, and nanoparticle synthesis. Figure 1

Enzyme-linked immunosorbent assays (ELISAs) are tests that uses antibody recognition and enzyme catalytic activity to identify a substance, and they have been widely used as a diagnostic tool in the clinic. However, performing an ELISA requires various liquid handling steps and long binding times. To solve this problem, we developed a magnetic microfluidic ELISA system (MMF-ELISA). Integration with nickel magnetic nanoparticles can streamline the ELISA process in a fully automated manner for

Since polymerase chain reaction (PCR) has become a vital tool for disease diagnosis, the development of precise applied PCR technologies in point-of care testing (POCT) has become more significant. The microfluidic-based PCR platform offers a great opportunity for on-site diagnosis efficiency, and the system is aimed at user-friendly access. Herein, we demonstrate a microfluidic system with simple operation that provides reliable nucleic acid results from 18 uniform droplets via LAMP qPCR detection. By using only micropipette regulation, users are able to control the nanoliter scale of the droplets in this valve-free and pump-free microfluidic (MF) chip. Based on the oil enclosure method and impermeable fabrication, we successfully preserved the reagent inside the microfluidic system, which significantly reduced the fluid loss and condensation. The relative standard deviation (RSD) of the fluorescence intensity between the droplets and during the heating process was

Summary Sweat-based wearable devices have attracted increasing attention by providing abundant physiological information and continuous measurement through noninvasive healthcare monitoring. Sweat pressure generated via sweat glands to the skin surface associated with osmotic effects may help to elucidate such parameters as physiological conditions and psychological factors. This study introduces a wearable device for measuring secretion sweat pressure through noninvasive, continuous monitoring. Secretion pressure is detected by a microfluidic chip that shows the resistance variance from a paired electrode pattern and transfers digital signals to a smartphone for real-time display. A human study demonstrates this measurement with different exercise activities, showing the pressure ranges from 1.3 to 2.5 kPa. This device is user-friendly and applicable to exercise training and personal health care. The convenience and easy-to-wear characteristics of this device may establish a foundation for future research investigating sweat physiology and personal health care., Graphical Abstract, Highlights • A wearable device sensing secreted sweat pressure for personal health care • A noninvasive method for real-time pressure monitoring displayed on a smartphone • Widely adopted in different individuals for ionic and temperature calibrations • Successful in situ measurements with exercise for 30 min, Sensor; Electronic Engineering; Biomedical Engineering; Electronic Materials

Extreme point-of-care testing (POCT) is a medical test performed at or near patients at a resource-limited condition. POCT technology has advantages over traditional medical lab tests for molecular detection and infection diagnosis, such as being simple, portable, low-cost, and user-friendly. However, some POCT devices might rely on bulky equipment, and some might be easily influenced by components in biofluid, which might result in higher prices and lower accuracy. In this paper, we demonstrated a low-cost method for detecting bacterial infection in the early stage. We designed a hand-powered centrifugal microfluidic (CMF) disc with magnetic chitosan beads (MCBs) to detect specific circulating antibodies in human whole blood. Nine identical units was used for calibration curve plotting and sample testing. The MCBs, generated with another microfluidic chip and coated with MBL proteins (biomarker of drug-resistant Streptococcus pneumoniae, DRSP, taken as an example for bacterial infection), were served as the substrate of sandwich-structured enzyme-linked immunosorbent assays (ELISA) and as the micro stirring sphere at the same time. The limit of detection (LOD) in PBS and human whole blood were 22.67 ng/mL and 24.83 ng/mL, respectively. The comparison between calibration curves from the antibody spiked in human whole blood and that in PBS was shown to prove the high compatibility and low interference of biofluid, and the recovery rate was 92 %. In conclusion, since our low-cost, time-saving, and user-friendly hand-powered CMF device with minimally consumed electricity detected the target antibody precisely, we believe that other similar assays would be feasible as well. Therefore, we are firmly convinced that this alternative POCT device may lead to the development of next-generation healthcare diagnoses.

We report a peptide-based sensor that involves a multivalent interaction with L-ascorbate 6-phosphate lactonase (UlaG), a protein marker of Streptococcus pneumonia. By integrating the antifouling feature of the sensor, we significantly improved the signal-to-noise ratio of UlaG detection. The antifouling surface was fabricated via electrodeposition using an equivalent mixture of 4-amino-N,N,N-trimethylanilinium and 4-aminobenzenesulfonate. This antifouling layer not only effectively reduces the non-specific adsorption on the biosensor but also decreases the charge transfer resistance (Rct) of the screen-printed carbon electrode. The aniline-modified S7 peptide, an UlaG-binding peptide, was pre-synthesized and further electrochemically modified to bind onto the antifouling layer. Bio-electrochemical analysis confirms that the antifouling S7-peptide sensor binds strongly to the UlaG with a dissociation constant (Kd) = 0.5 nM. This strong interaction can be attributed to a multivalent interaction between the biosensor and the heximeric form of UlaG. To demonstrate the potential for clinical application, further detection of Streptococcus pneumonia from 50 to 5 × 10 4 CFU/mL were successfully performed in 25% human serum.

Blood tests provide crucial diagnostic information regarding several diseases. A key factor that affects the precision and accuracy of blood tests is the interference of red blood cells; however, the conventional methods of blood separation are often complicated and time consuming. In this study, we devised a simple but high-efficiency blood separation system on a self-strained microfluidic device that separates 99.7% of the plasma in only 6 min. Parameters, such as flow rate, design of the filter trench, and the relative positions of the filter trench and channel, were optimized through microscopic monitoring. Moreover, this air-difference-driven device uses a cost-effective and easy-to-use heater strip that creates a low-pressure environment in the microchannel within minutes. With the aforementioned advantages, this blood separation device could be another platform choice for point-of-care testing.

A biosensor is generally defined as an analytical device, which converts the biochemical responses into the quantifiable electronic signals. Its extensive utilities in medical diagnosis, toxicity testing, chemical analysis, food industry, and many other areas for quantitative assessments has appeared. Quartz crystal microbalance and field-effect transistor based devices have been demonstrated to possess exceptional characteristics and outstanding performance while conjugated with the advanced nanotechnology. However, both devices still have to face the nonspecific binding issue, which is a headache for researchers on all biosensor platforms. In our research, we have efficaciously reduce 95% nonspecific binding via immobilize the zwitterionic layer on the surface of the chip. Moreover, we integrate microfluidics, nanoparticles, rapid surface modification on several bio-sensing platforms to efficiently pretreat specimens and detect target bio-molecules. In addition, a series advanced microfluidic ships are designed for lymphocyte isolation, active sperm sorting, and nanoparticle synthesis. Figure 1

A biosensor is generally defined as an analytical device, which converts the biochemical responses into the quantifiable electronic signals. Its extensive utilities in medical diagnosis, toxicity testing, chemical analysis, food industry, and many other areas for quantitative assessments has appeared. Quartz crystal microbalance and field-effect transistor based devices have been demonstrated to possess exceptional characteristics and outstanding performance while conjugated with the advanced nanotechnology. However, both devices still have to face the nonspecific binding issue, which is a headache for researchers on all biosensor platforms. In our research, we have efficaciously reduce 95% nonspecific binding via immobilize the zwitterionic layer on the surface of the chip. Moreover, we integrate microfluidics, nanoparticles, rapid surface modification on several bio-sensing platforms to efficiently pretreat specimens and detect target biomolecules. In addition, a series advanced microfluidic ships are designed for lymphocyte isolation, active sperm sorting, and nanoparticle synthesis. Figure 1

Dopamine (DA) is an important neurotransmitter that is involved in neuronal signal transduction and several critical illnesses. However, the concentration of DA is extremely low in patients and is difficult to detect using existing electrochemical biosensors with detection limits typically around nanomolar levels (∼10(-9) M). Here, we developed a nanoelectronic device as a biosensor for ultrasensitive and selective DA detection by modifying DNA-aptamers on a multiple-parallel-connected (MPC) silicon nanowire field-effect transistor (referred to as MPC aptamer/SiNW-FET). Compared with conventional electrochemical methods, the MPC aptamer/SiNW-FET has been demonstrated to improve the limit of DA detection to10(-11) M and to possess a detection specificity that is able to distinguish DA from other chemical analogues, such as ascorbic acid, catechol, phenethylamine, tyrosine, epinephrine, and norepinephrine. This MPC aptamer/SiNW-FET was also applied to monitor DA release under hypoxic stimulation from living PC12 cells. The real-time recording of the exocytotic DA induced by hypoxia reveals that the increase in intracellular Ca(2+) that is required to trigger DA secretion is dominated by an extracellular Ca(2+) influx, rather than the release of intracellular Ca(2+) stores.

In applications of silicon nanowire field-effect transistors (SiNW-FETs) as biosensors, the SiNW-FETs conventionally are all area modified (AAM), with receptors covering not only the minute SiNW surface area but also the relatively large surrounding substrate area. In this study, using a bottom-up technique, we successfully fabricated selective surface modified (SSM) SiNW-FETs with the receptors on the SiNW sensing surface only. In this approach, the strategy was to modify the SiNWs with a chemical linker of 3-aminopropyltrimethoxysilane (APTMS) prior to photolithographic fabrication of the device. The APTMS molecules modifying the SiNWs survived the harsh photolithographic processes, including coating with photoresist, washing with organic solvent, and thermal annealing. These SSM SiNW-FETs also exhibited desirable electrical characteristics such as ohmic contact and high transconductance. Using the biotin-avidin binding system, we showed that the faster response time and smaller sample requirements of the SSM SiNW-FETs, relative to the conventional AAM SiNW-FETs, clearly show that restricting the surface modification of the SiNW-FETs substantially improves their detection sensitivity. Detection with a SSM boronic acid-modified SiNW-FET of the dopamine released under high-K(+) buffer stimulation from living PC12 cells also demonstrates that SiNW-FETs can serve as highly sensitive biosensors for biomedical diagnosis. In binding affinity measurements with SiNW-FETs, the dissociation constants (Kd) of the biotin-avidin and dopamine-boronic acid complexes were determined to be 15 ± 1 fM and 33 ± 8 fM, respectively.

Understanding how proteins interact with each other is the basis for studying the biological mechanisms behind various physiological activities. Silicon nanowire field-effect transistors (SiNW-FETs) are sensitive sensors used to detect biomolecular interactions in real-time. However, the majority of the applications that use SiNW-FETs are for known interactions between different molecules. To explore the capability of SiNW-FETs as fast screening devices to identify unknown interacting molecules, we applied mass spectrometry (MS) to analyze molecules reversibly bound to the SiNW-FETs. Calmodulin (CaM) is a Ca(2+)-sensing protein that is ubiquitously expressed in cells and its interaction with target molecules is Ca(2+)-dependent. By modifying the SiNW-FET surface with glutathione, glutathione S-transferase (GST)-tagged CaM binds reversibly to the SiNW-FET. We first verified the Ca(2+)-dependent interaction between GST-CaM and purified troponin I, which is involved in muscle contraction, through the conductance changes of the SiNW-FET. Furthermore, the cell lysate containing overexpressed Ca(2+)/CaM-dependent protein kinase IIα induced a conductance change in the GST-CaM-modified SiNW-FET. The bound proteins were eluted and subsequently identified by MS as CaM and kinase. In another example, candidate proteins from neuronal cell lysates interacting with calneuron I (CalnI), a CaM-like protein, were captured with a GST-CalnI-modified SiNW-FET. The proteins that interacted with CalnI were eluted and verified by MS. The Ca(2+)-dependent interaction between GST-CalnI and one of the candidates, heat shock protein 70, was re-confirmed via the SiNW-FET measurement. Our results demonstrate the effectiveness of combining MS with SiNW-FETs to quickly screen interacting molecules from cell lysates.

Summary Silicon nanowire field-effect transistors (SiNW-FETs) have recently drawn tremendous attention as a promising tool in biosensor design because of their ultrasensitivity, selectivity, and label-free and real-time detection capabilities. Here, we review the recently published literature that describes the device fabrication and biomedical applications of SiNW-FET sensors. For practical uses, SiNW-FETs can be delicately designed to be a reusable device via a reversible surface functionalization method. In the fields of biological research, SiNW-FETs are employed in the detections of proteins, DNA sequences, small molecules, cancer biomarkers, and viruses. The methods by which the SiNW-FET devices were integrated with these representative examples and advanced to virus infection diagnosis or early cancer detection will be discussed. In addition, the utilization of SiNW-FETs in recording the physiological responses from cells or tissues will also be reviewed. Finally, the novel design of a three dimensional (3D) nano-FET probe with kinked SiNWs for recording intracellular signals will be highlighted in this review.

Boronic acids (BAs) provide strong potential in orientation immobilization of antibody and the modification method is crucial for efficiency optimization. A highly effective method has been developed for rapid antibody immobilization on gold electrodes through the electrodeposition of a BA–containing linker in this study. Aniline-based BA forms a condense layer while antibody could automatically immobilize on the surface of the electrode. Compare to traditional self-assembled monolayer method, the electrodeposition process dramatically reduces the modification time from days to seconds. It also enhances the immobilized efficiency from 95 to 408 (ng/cm2) with a strong preference being exhibited for shorter aniline-based linkers.

Rhodobacter sphaeroides produces a novel cytochrome, designated as SHP (sphaeroides haem protein), that is unusual in having asparagine as a redox-labile haem ligand. The gene encoding SHP is contained within an operon that also encodes a DHC (dihaem cytochrome c) and a membrane-associated cytochrome b. DHC and SHP have been shown to have high affinity for each other at low ionic strength (Kd=0.2 μM), and DHC is able to reduce SHP very rapidly. The reduced form of the protein, SHP2+ (reduced or ferrous SHP), has high affinity for both oxygen and nitric oxide (NO). It has been shown that the oxyferrous form, SHP2+–O2 (oxygen-bound form of SHP), reacts rapidly with NO to produce nitrate, whereas SHP2+–NO (the NO-bound form of SHP) will react with superoxide with the same product formed. It is therefore possible that SHP functions physiologically as a nitric oxide dioxygenase, protecting the organism against NO poisoning, and we propose a possible mechanism for this process.

A new approach to immobilize zwitterionic molecules rapidly and highly efficiently on a gold surface applies aniline-based electrodeposition. The zwitterion-functionalized antifouling surface enables a decrease of the adsorption of non-specific proteins by 95% from fetal bovine serum (FBS, 10%).

Electrical biosensors based on silicon nanowire field-effect transistors (SiNW-FETs) have attracted enormous interest in the biosensing field. SiNW-FETs have proven to be significant and efficient in detecting diverse biomolecular species with the advantages of high probing sensitivity, target selectivity, real-time recording and label-free detection. In recent years, significant advances in biosensors have been achieved, particularly for cellular investigation and biomedical diagnosis. In this critical review, we will report on the latest developments in biosensing with SiNW-FETs and discuss recent advancements in the innovative designs of SiNW-FET devices. This critical review introduces the basic instrumental setup and working principle of SiNW-FETs. Technical approaches that attempted to enhance the detection sensitivity and target selectivity of SiNW-FET sensors are discussed. In terms of applications, we review the recent achievements with SiNW-FET biosensors for the investigations of protein–protein interaction, DNA/RNA/PNA hybridization, virus detection, cellular recording, biological kinetics, and clinical diagnosis. In addition, the novel architecture designs of the SiNW-FET devices are highlighted in studies of live neuron cells, electrophysiological measurements and other signal transduction pathways. Despite these remarkable achievements, certain improvements remain necessary in the device performance and clinical applications of FET-based biosensors; thus, several prospects about the future development of nanowire transistor-based instruments for biosensing employments are discussed at the end of this review.

Silicon nanowire field effect transistors (SiNW-FETs) have shown great promise as biosensors in highly sensitive, selective, real-time and label-free measurements. While applications of SiNW-FETs for detection of biological species have been described in several publications, less attention has been devoted to summarize the conjugating methods involved in linking organic bio-receptors with the inorganic transducer and the strategies of improving the sensitivity of devices. This article attempts to focus on summarizing the various organic immobilization approaches and discussing various sensitivity improving strategies, that include (I) reducing non-specific binding, (II) alignment of the probes, (III) enhancing signals by charge reporter, (IV) novel architecture structures, and (V) sensing in the sub-threshold regime.

We have previously identified a new centrosomal protein, centrosomal protein 4.1-associated protein (CPAP), which is associated with the γ-tubulin complex. Here, we report that CPAP carries a novel microtubule-destabilizing motif that not only inhibits microtubule nucleation from the centrosome but also depolymerizes taxol-stabilized microtubules. Deletion mapping and functional analyses have defined a 112-residue CPAP that is necessary and sufficient for microtubule destabilization. This 112-residue CPAP directly recognizes the plus end of a microtubule and inhibits microtubule nucleation from the centrosome. Biochemical and functional analyses revealed that this 112-residue CPAP also binds to tubulin dimers, resulting in the destabilization of microtubules. Using the tetracycline-controlled system (tet-off), we observed that overexpression of this 112-residue CPAP inhibits cell proliferation and induces apoptosis after G2/M arrest. The possible mechanisms of how this 112-residue motif in CPAP that inhibits microtubule nucleation from the centrosome and disassembles preformed microtubules are discussed.