Carbon nanotube transistors have outstanding potential for electronic detection of biomolecules in solution. The physical mechanism underlying sensing however remains controversial, which hampers full exploitation these promising nanosensors. Previously suggested mechanisms are electrostatic gating, changes gate coupling, carrier mobility changes, and Schottky barrier effects. We argue that each has its characteristic effect on the liquid dependence device conductance. By studying both...

Abstract DNA intercalators are widely used as fluorescent probes to visualize and transactions in vivo vitro . It is well known that they perturb structure stability, which can turn influence DNA-processing by proteins. Here we elucidate this perturbation combining single-dye fluorescence microscopy with force spectroscopy measuring the kinetics of intercalation mono- bis-intercalating cyanine dyes SYTOX Orange, Green, SYBR Gold, YO-PRO-1, YOYO-1 POPO-3. We show their DNA-binding affinity...

We demonstrate the use of individual single-walled carbon nanotubes (SWNTs) as nanoelectrodes for electrochemistry. SWNTs were contacted by nanolithography, and cyclic voltammetry was performed in aqueous solutions. Interestingly, metallic semiconducting yielded similar steady-state voltammetric curves. clarify this behavior through a model that considers electronic structure SWNTs. Interfacial electron transfer to is observed be very fast but can nonetheless resolved due nanometer critical...

We present a theoretical description of the kinetics electrochemical charge transfer at single-walled carbon nanotube (SWNT) electrodes, explicitly taking into account SWNT electronic band structure. SWNTs have distinct and low density states (DOS), as expressed by small value quantum capacitance. show that this greatly affects alignment occupation in voltammetric experiments thus electrode kinetics. model electrochemistry metallic semiconducting well graphene applying Gerischer−Marcus...

Field-effect transistors based on single-walled carbon nanotubes (SWNTs) and graphene can function as highly sensitive nanoscale (bio)sensors in solution. Here, we compare experimentally how SWNT respond to changes the composition of aqueous electrolyte which they are immersed. We show that conductance SWNTs is strongly affected by ionic strength, pH, type ions present, a manner be qualitatively different for devices. this sensitivity results from combination mechanisms including...

Carbon nanotube transistors show tremendous potential for electronic detection of biomolecules in solution. However, the nature and magnitude sensing signal upon molecular adsorption have so far remained controversial. Here, authors that choice reference electrode is critical resolves much previous controversy. The eliminate artifacts related to by using a well-defined accurately control solution potential. Upon addition bovine serum albumin proteins, measure transistor threshold shift −15mV...

In preparation for mitotic cell division, the nuclear DNA of human cells is compacted into individualized, X-shaped chromosomes1. This metamorphosis driven mainly by combined action condensins and topoisomerase IIα (TOP2A)2,3, has been observed using microscopy over a century. Nevertheless, very little known about structural organization chromosome. Here we introduce workflow to interrogate chromosomes based on optical trapping manipulation. allows high-resolution force measurements...

We report an experimental study of 1/f noise in liquid-gated graphene transistors. show that the gate dependence is well described by a charge-noise model, whereas Hooge's empirical relation fails to describe data. At low carrier density, can be attributed fluctuating charges close proximity graphene, while at high density it consistent with due scattering channel. The charge power scales inversely device area, and bilayer devices exhibit lower than single-layer devices. In air, observed also model.

Architectural proteins have an important role in shaping the genome and act as global regulators of gene expression. How these jointly modulate plasticity is largely unknown. In archaea, one most abundant proteins, Alba, considered to a key organizing genome. Here we characterize multimodal architectural properties interplay Alba1 Alba2 using single-molecule imaging manipulation techniques. We demonstrate that two paralogues can bridge rigidify DNA between influences balance effects. Our...

Significance The mechanism of RAD51-recombinase filament formation is visualized and quantified with single-molecule resolution using a combination dual optical tweezers, fluorescence microscopy, microfluidics. With this method, short-lived transient intermediates formed during nascent RAD51 assembly were observed directly. It that nuclei consisting variable number monomers bind from solution to DNA, an interaction time increases nucleus size. Nuclei remain bound DNA long enough can grow by...

Optical tweezers and single-molecule polarization imaging reveal structural features of overstretched DNA.

The signal-to-noise ratio (SNR) for real-time biosensing with liquid-gated carbon nanotube transistors is crucial exploring the limits of their sensitivity, but has not been studied thus far. Although often performed at high transconductance where device displays largest gate response, here we show that maximum SNR actually obtained when operated in subthreshold regime. In ON-state, additional contributions to noise can lead a reduction by up factor 5. For devices passivated contact regions,...

In a previous paper (Syrjänen et al., 2014), we reported the first structural characterisation of synaptonemal complex (SC) protein, SYCP3, which led us to propose model for its role in chromosome compaction during meiosis. As component SC lateral element, SYCP3 has critical defining specific architecture required correct meiotic progression. model, chromosomal DNA caused by would result from ability bridge distant sites on molecule with DNA-binding domains located at each end strut-like...

Abstract Objective: To validate automated and quantitative three‐dimensional analysis of coronary plaque composition using intracoronary ultrasound (ICUS). Background: ICUS displays different tissue components based on their acoustic properties in 256 grey‐levels. We hypothesised that computer‐assisted image (differential echogenicity) would permit quantification several atherosclerotic plaques. Methods Results: Ten 40‐mm‐long left anterior descending specimens were excised during autopsy...

The noise properties of single-walled carbon nanotube transistors (SWNT-FETs) are essential for the performance electronic circuits and sensors. Here, we investigate mechanism responsible low-frequency in liquid-gated SWNT-FETs its scaling with length channel down to nanometer scale. We show that gate dependence amplitude provides strong evidence a recently proposed charge-noise model. find power charge scales as inverse SWNT-FET. Our measurements also surprisingly ionic strength surrounding...

The three-dimensional structure of DNA is highly susceptible to changes by mechanical and biochemical cues in vivo vitro. In particular, large increases base pair spacing compared regular B-DNA are effected (over)stretching intercalation compounds that widely used biophysical/chemical assays drug treatments. We present single-molecule experiments a three-state statistical model provide quantitative understanding the interplay between B-DNA, overstretched intercalated DNA. predictions this...

We report on the use of polymyxin (PM), a cyclic cationic lipodecapeptide, as an electrode modifier for studying protein film voltammetry (PFV) Au and single-walled carbon nanotube (SWNT) electrodes. Pretreating electrodes with PM allows subsequent immobilization active submonolayer [NiFe]-hydrogenase from Allochromatium vinosum (Av H2ase). Probed by (CV), adsorbed enzyme exhibits characteristic electrocatalytic behavior that is stable several hours under continuous potential cycling. An...

Fluorescence microscopy is invaluable to a range of biomolecular analysis approaches. The required labeling proteins interest, however, can be challenging and potentially perturb functionality as well cause imaging artefacts photo bleaching issues. Here, we introduce inverse (super-resolution) unlabeled bound DNA. In this new method, use DNA-binding fluorophores that transiently label bare DNA but not protein-bound addition demonstrating diffraction-limited imaging, show Binding-Activated...

Significance Primary cilia are important organelles that exist in almost all eukaryotic cells. Intraflagellar transport (IFT) is a motor-protein–driven bidirectional intracellular mechanism cilia. Previous studies have shown motors Caenorhabditis elegans chemosensory undergo rapid turnarounds to effectively work together driving orderly IFT. The of motor has, however, remained unclear. Here, using combination advanced fluorescence imaging and single-molecule analysis, we directly show the...

Coronary atherosclerosis is a dynamic process, which progresses differently in coronary segments containing noncalcified or calcified plaques. This may have implications for the study of effects therapy on progression/regression.To test this hypothesis, we performed post-hoc analysis data randomized trial perindopril treatment was compared with placebo progression/regression regard to degree calcification.The intracoronary ultrasound 118 patients, who were enrolled multicentre,...