Single Molecule Electronic Devices Song, Hyunwook; Reed, Mark A.; Lee, Takhee
Advanced materials (Weinheim),
April 12, 2011, Letnik:
23, Številka:
14
Journal Article
Recenzirano
Single molecule electronic devices in which individual molecules are utilized as active electronic components constitute a promising approach for the ultimate miniaturization and integration of ...electronic devices in nanotechnology through the bottom‐up strategy. Thus, the ability to understand, control, and exploit charge transport at the level of single molecules has become a long‐standing desire of scientists and engineers from different disciplines for various potential device applications. Indeed, a study on charge transport through single molecules attached to metallic electrodes is a very challenging task, but rapid advances have been made in recent years. This review article focuses on experimental aspects of electronic devices made with single molecules, with a primary focus on the characterization and manipulation of charge transport in this regime.
Single molecules provide ideal systems to investigate charge transport on the molecular scale, which is a subject of intense current interest for both practical applications and achieving a fundamental understanding of novel physical phenomena that take place in molecular‐scale charge transport. This review article focuses on experimental aspects of electronic devices made with single molecules.
Older patients who are hospitalized for acute decompensated heart failure have high rates of physical frailty, poor quality of life, delayed recovery, and frequent rehospitalizations. Interventions ...to address physical frailty in this population are not well established.
We conducted a multicenter, randomized, controlled trial to evaluate a transitional, tailored, progressive rehabilitation intervention that included four physical-function domains (strength, balance, mobility, and endurance). The intervention was initiated during, or early after, hospitalization for heart failure and was continued after discharge for 36 outpatient sessions. The primary outcome was the score on the Short Physical Performance Battery (total scores range from 0 to 12, with lower scores indicating more severe physical dysfunction) at 3 months. The secondary outcome was the 6-month rate of rehospitalization for any cause.
A total of 349 patients underwent randomization; 175 were assigned to the rehabilitation intervention and 174 to usual care (control). At baseline, patients in each group had markedly impaired physical function, and 97% were frail or prefrail; the mean number of coexisting conditions was five in each group. Patient retention in the intervention group was 82%, and adherence to the intervention sessions was 67%. After adjustment for baseline Short Physical Performance Battery score and other baseline characteristics, the least-squares mean (±SE) score on the Short Physical Performance Battery at 3 months was 8.3±0.2 in the intervention group and 6.9±0.2 in the control group (mean between-group difference, 1.5; 95% confidence interval CI, 0.9 to 2.0; P<0.001). At 6 months, the rates of rehospitalization for any cause were 1.18 in the intervention group and 1.28 in the control group (rate ratio, 0.93; 95% CI, 0.66 to 1.19). There were 21 deaths (15 from cardiovascular causes) in the intervention group and 16 deaths (8 from cardiovascular causes) in the control group. The rates of death from any cause were 0.13 and 0.10, respectively (rate ratio, 1.17; 95% CI, 0.61 to 2.27).
In a diverse population of older patients who were hospitalized for acute decompensated heart failure, an early, transitional, tailored, progressive rehabilitation intervention that included multiple physical-function domains resulted in greater improvement in physical function than usual care. (Funded by the National Institutes of Health and others; REHAB-HF ClinicalTrials.gov number, NCT02196038.).
Several types of nanofluidic devices based on nanopores and nanochannels have been reported to yield ionic current rectification, with the aim to control the delivery of chemical species in ...integrated systems. However, the rectifying properties obtained by existing approaches cannot be altered once the devices are made. It would be desirable to have the ability to modulate the predefined properties in situ without introducing external chemical stimuli. Here we report a field-effect reconfigurable nanofluidic diode, with a single asymmetrically placed gate or dual split-gate on top of the nanochannel. The forward/reverse directions of the diode as well as the degrees of rectification can be regulated by the application of gate voltages. Compared with the stimuli-responsive tuning of the rectification properties, the electrostatic modulation offers a fully independent and digitally programmable approach for controlling the preferential conduction of ions and molecules in fluids. This device would serve as a building block for large-scale integration of reconfigurable ionic circuits.
Monitoring the binding affinities and kinetics of protein interactions is important in clinical diagnostics and drug development because such information is used to identify new therapeutic ...candidates. Surface plasmon resonance is at present the standard method used for such analysis, but this is limited by low sensitivity and low-throughput analysis. Here, we show that silicon nanowire field-effect transistors can be used as biosensors to measure protein-ligand binding affinities and kinetics with sensitivities down to femtomolar concentrations. Based on this sensing mechanism, we develop an analytical model to calibrate the sensor response and quantify the molecular binding affinities of two representative protein-ligand binding pairs. The rate constant of the association and dissociation of the protein-ligand pair is determined by monitoring the reaction kinetics, demonstrating that silicon nanowire field-effect transistors can be readily used as high-throughput biosensors to quantify protein interactions.
Solid-state nanofluidic devices have proven to be ideal systems for studying the physics of ionic transport at the nanometer length scale. When the geometrical confining size of fluids approaches the ...ionic Debye screening length, new transport phenomena occur, such as surface mediated transport and permselectivity. Prior work has explored these effects extensively in monovalent systems (e.g., predominantly KCl and NaCl). In this report, we present a new characterization method for the study of divalent ionic transport and have unambiguously observed divalent charge inversion at solid/fluid interfaces. This observation has important implications in applications ranging from biology to energy conversion.
Observation of molecular orbital gating Kim, Youngsang; Jeong, Heejun; Song, Hyunwook ...
Nature (London),
12/2009, Letnik:
462, Številka:
7276
Journal Article
Recenzirano
The control of charge transport in an active electronic device depends intimately on the modulation of the internal charge density by an external node. For example, a field-effect transistor relies ...on the gated electrostatic modulation of the channel charge produced by changing the relative position of the conduction and valence bands with respect to the electrodes. In molecular-scale devices, a longstanding challenge has been to create a true three-terminal device that operates in this manner (that is, by modifying orbital energy). Here we report the observation of such a solid-state molecular device, in which transport current is directly modulated by an external gate voltage. Resonance-enhanced coupling to the nearest molecular orbital is revealed by electron tunnelling spectroscopy, demonstrating direct molecular orbital gating in an electronic device. Our findings demonstrate that true molecular transistors can be created, and so enhance the prospects for molecularly engineered electronic devices.
The hypercoagulable state associated with pancreatic adenocarcinoma (PDA) results in increased risk of venous thromboembolism, leading to substantial morbidity and mortality. Recently, neutrophil ...extracellular traps (NETs), whereby activated neutrophils release their intracellular contents containing DNA, histones, tissue factor, high mobility group box 1 (HMGB1) and other components have been implicated in PDA and in cancer-associated thrombosis.
Utilizing an orthotopic murine PDA model in C57/Bl6 mice and patient correlative samples, we studied the role of NETs in PDA hypercoagulability and targeted this pathway through treatment with the NET inhibitor chloroquine. PAD4 and RAGE knockout mice, deficient in NET formation, were used to study the role of NETs in platelet aggregation, release of tissue factor and hypercoagulability. Platelet aggregation was assessed using collagen-activated impedance aggregometry. Levels of circulating tissue factor, the initiator of extrinsic coagulation, were measured using ELISA. Thromboelastograms (TEGs) were performed to assess hypercoagulability and changes associated with treatment. Correlative data and samples from a randomized clinical trial of preoperative gemcitabine/nab-paclitaxel with and without hydroxychloroquine were studied and the impact of treatment on venous thromboembolism (VTE) rate was evaluated.
The addition of NETs to whole blood stimulated platelet activation and aggregation. DNA and the receptor for advanced glycation end products (RAGE) were necessary for induction of NET associated platelet aggregation. PAD4 knockout tumor-burdened mice, unable to form NETs, had decreased aggregation and decreased circulating tissue factor. The NET inhibitor chloroquine reduces platelet aggregation, reduces circulating tissue factor and decreases hypercoagulability on TEG. Review of correlative data from patients treated on a randomized protocol of preoperative chemotherapy with and without hydroxychloroquine demonstrated a reduction in peri-operative VTE rate from 30 to 9.1% with hydroxychloroquine that neared statistical significance (p = 0.053) despite the trial not being designed to study VTE.
NETs promote hypercoagulability in murine PDA through stimulation of platelets and release of tissue factor. Chloroquine inhibits NETs and diminishes hypercoagulability. These findings support clinical study of chloroquine to lower rates of venous thromboembolism in patients with cancer.
This study reports correlative data from two clinical trials that registered with clinicaltrials.gov, NCT01128296 (May 21, 2010) and NCT01978184 (November 7, 2013).
Nanowire field effect transistors (NW-FETs) can serve as ultrasensitive detectors for label-free reagents. The NW-FET sensing mechanism assumes a controlled modification in the local channel electric ...field created by the binding of charged molecules to the nanowire surface. Careful control of the solution Debye length is critical for unambiguous selective detection of macromolecules. Here we show the appropriate conditions under which the selective binding of macromolecules is accurately sensed with NW-FET sensors.
A potentiometric non-enzymatic sensor using off-chip extended-gate field effect transistor (EGFET) with a ferrocenyl-alkanethiol modified gold electrode is demonstrated for determining the uric acid ...concentration in human serum and urine. Hexacyanoferrate (II) and (III) ions are used as redox reagent. This potentiometric sensor measures the interface potential on the ferrocene immobilized gold electrode, which is modulated by the redox reaction between uric acid and hexacyanoferrate ions. The device shows a near Nernstian response to uric acid and is highly specific. The interference that comes from glucose, bilirubin, ascorbic acid and hemoglobin is negligible in normal concentration range of these interferents. The sensor also exhibits excellent long term reliability. This extended gate field effect transistor based sensors can be used as a point of care UA testing tool, due to the small size, low cost, and low sample volume consumption.
•Non-enzymatic potentiometric sensor for uric acid detection in human.•Highly specific and near Nernstian response to uric acid.•Excellent long term reliability for more than half a year.•Common interferences are negligible in normal concentrations.
To determine the concentration of amphotericin B that would be both effective against Candida albicans contamination and safe for corneal endothelial cells (CECs) in cold storage conditions.
...Triplicate media cultures were inoculated with 10 colony-forming units (CFUs)/mL of C. albicans (American Type Culture Collection 10231), supplemented with amphotericin B (0-20 μg/mL), stored in cold conditions (2°C-8°C) for 72 hours, and analyzed quantitatively for CFUs. C. albicans concentration in each sample was determined initially and after 6, 24, 48, and 72 hours of storage. CEC mitochondrial function (oxygen consumption rate), apoptosis, and necrosis were examined in donor corneas after 7 days of amphotericin B exposure and compared with untreated controls. CEC viability was also examined by calcein-AM staining and Fiji segmentation after 72 hours or 2 weeks of amphotericin B exposure to mimic potential eye bank practices.
Amphotericin B concentrations of 1.25, 2.5, and 5.0 μg/mL resulted in 0.47, 1.11, and 1.21 log10 CFU reduction after only 6 hours of cold storage and continued to decrease to 3.50, 3.86, and 4.49 log10 reductions after 72 hours, respectively. By contrast, amphotericin B 0.255 µg/mL showed only 1.01 log10 CFU reduction after 72 hours of incubation. CEC mitochondrial function and viability did not differ in donor corneas exposed to amphotericin B ≤2.59 μg/mL compared with the controls.
Optimal efficacy of amphotericin B against C. albicans is achieved in cold storage conditions at concentrations ≥1.25 μg/mL, and 2.5 μg/mL reduces Candida contamination by >90% after 6 hours of cold storage without sacrificing CEC health.
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