Brightening of Dark Excitons in Single-Walled Carbon Nanotubes:Investigation by Many-Body Green’s Function Theory

Optical excitations of the hybrids,which are assembled by coupling single-walled carbon nanotubes(SWCNTs)with organic molecules through van der Waals interactions,are studied using ab initio manybody Green’s function theory.We take the semiconducting(7,0)SWCNT,the squarylium and oligothiophene molecules as the example.The E11 and E22 absorption peaks of the(7,0)tube can be redshifted by tens of meV.Most importantly,the lowest dark exciton of the(7,0)tube at the lower-energy side of E11 can be brightened by the interaction between the nanotube and molecules.Position of this new satellite absorption peak is influenced by the type of adsorbed molecule.These findings may be useful for tuning the emission energy and emission efficiency of CNTs.

Low sample volume origami-paper-based graphene-modified aptasensors for label-free electrochemical detection of cancer biomarker-EGFR

In this work,an electrochemical paper-based aptasensor was fabricated for label-free and ultrasensitive detection of epidermal growth factor receptor(EGFR)by employing anti-EGFR aptamers as the bio-recognition element.The device used the concept of paper-folding,or origami,to serve as a valve between sample introduction and detection,so reducing sampling volumes and improving operation convenience.Amino-functionalized graphene(NH 2-GO)/thionine(THI)/gold particle(AuNP)nanocomposites were used to modify the working electrode not only to generate the electrochemical signals,but also to provide an environment conducive to aptamer immobilization.Electrochemical characterization revealed that the formation of an insulating aptamer–antigen immunocomplex would hinder electron transfer from the sample medium to the working electrode,thus resulting in a lower signal.The experimental results showed that the proposed aptasensor exhibited a linear range from 0.05 to 200 ngmL^(−1)(R^(2)=0.989)and a detection limit of 5pgmL^(−1) for EGFR.The analytical reliability of the proposed paper-based aptasensor was further investigated by analyzing serum samples,showing good agreement with the gold-standard enzyme-linked immunosorbent assay.

Lattice vibrational modes and phonon thermal conductivity of singlelayer GaGeTe

Exploring the vibrational properties of experimental or theoretical finding of new phase twodimensional(2D)materials is one key to expand their promising application.The GaGeTe monolayer with high carrier mobility,tunable band structure,and low cleavage energy attracts rapidly growing interests in electronics.However,their vibrational modes and phonon properties are not explored.Based on first-principles calculations within the framework of density functional perturbation theory,we systematically study the lattice vibrational modes as well as phonon thermal conductivity of single-layer GaGeTe,which could be exfoliated from the experimentally synthesized GaGeTe crystal.We find that the frequencies and intensities of A1g and Eg Raman modes,contributing to the main peaks in Raman spectra of monolayer GaGeTe,show distinct responses to different external strains.The calculated lattice thermal conductivity of GaGeTe is about 58 Wm-1 K1,which is comparable to that of MoS2(around 52 Wm1K1)and two orders of magnitude lower than that of graphene(2000 Wm1K1)at room temperature.This is mainly due to the partial couple for acoustic branches and low frequency optic phonon branches,moderate group velocity,strong anharmonic ZA phonon branch.Moreover,atom substitution at tellurium could be as an effective strategy to further decrease lattice thermal conductivity.Our findings fill in the gap about the thermal transport properties of GaGeTe monolayer and trigger for further experimental verification of the predicted properties.