We report the synthesis and evidence of graphene fluoride, a two-dimensional wide bandgap semiconductor derived from graphene. Graphene fluoride exhibits hexagonal crystalline order and strongly insulating behavior with resistance exceeding 10 GΩ at room temperature. Electron transport in graphene fluoride is well described by variable-range hopping in two dimensions due to the presence of localized states in the band gap. Graphene obtained through the reduction of graphene fluoride is highly conductive, exhibiting a resistivity of less than 100 kΩ at room temperature. Our approach provides a new path to reversibly engineer the band structure and conductivity of graphene for electronic and optical applications.

Adatoms offer an effective route to modify and engineer the properties of graphene.In this work, we create dilute fluorinated graphene using a clean, controlled and reversible approach. At low carrier densities, the system is strongly localized and exhibits an unexpected, colossal negative magnetoresistance. The zero-field resistance is reduced by a factor of 40 at the highest field of 9 T and shows no sign of saturation. Unusual "staircase" field dependence is observed below 5 K. The magnetoresistance is highly anisotropic. We discuss possible origins, considering quantum interference effects and adatom-induced magnetism in graphene.Defects and adsorbates have proven powerful in altering the electronic properties of graphene through doping, scattering and band gap induction [1][2][3][4][5][6][7][8]. In particular, point defects such as vacancies and adatoms can perturb the electronic states of graphene strongly, leading to midgap states [1] and drastic change of transport properties [4][5][6][7][8].With the ability to control the form and density of defects and the assistance of microscopic imaging tools, defect-engineered graphene can be used as model systems to 2 study the complex role of disorder in two dimensions. Moreover, it has been predicted that point defects may also introduce local magnetic moments and magnetic interactions unavailable in pristine graphene. Calculations show that the peculiar nature of Dirac fermions gives rise to ferromagnetic (antiferromagnetic) interactions among moments occupying the same (opposite) graphene sublattice and possible competing magnetic orders [9,10]. Evidence of magnetism in single-layer graphene remains elusive to date. A controllable defect coverage together with in situ wide tunability of the electronic states makes defective graphene an ideal venue to explore the above novel physical phenomena.In this Letter, we create clean, dilute fluorinated graphene (DFG) and report the observation of unexpected, colossal, negative magnetoresistance (MR). As the electron density is reduced to below the density of fluorine adatoms, the system undergoes a transition from weak to strong localization. In the strongly localization regime, a perpendicular magnetic field drastically reduces the DFG resistance by up to 40-fold at 9 T, while an-plane magnetic field causes only a very small positive MR. We compare our data to existing orbital mechanisms and discuss the possibility of magnetism in our samples.Fluorination controls the properties of carbon materials effectively [11]. Fluorine adatoms are chemically simple and stable in ambient conditions. In this study, we work in the extreme dilute limit such that the properties of graphene dominate. Fluorine adatoms are covalently attached to graphene using CF 4 plasma [12]. This fluorination process is nearly completely reversible. We monitor the concentrations of fluorine adatoms and the unintentionally generated vacancies using Raman spectroscopy (Fig. 1a). With a carefully optimized recipe, the number of vacancies is min...

Abstract:The issue of whether local magnetic moments can be formed by introducing adatoms into graphene is of intense research interest because it opens the window to fundamental studies of magnetism in graphene, as well as of its potential spintronics applications. To investigate this question we measure, by exploiting the well-established weak localization physics, the phase coherence length L  in dilute fluorinated graphene. L  reveals an unusual saturation below ~ 10 K, which cannot be explained by non-magnetic origins. The corresponding phase breaking rate increases with decreasing carrier density and increases with increasing fluorine density. These results provide strong evidence for spin-flip scattering and points to the existence of adatominduced local magnetic moment in fluorinated graphene. Our results will stimulate further investigations of magnetism and spintronics applications in adatom-engineered graphene.Adatom-engineering has become an active research front in the field of graphene recently because it is a powerful tool to alter, control and engineer the transport, optical, and potentially magnetic properties of graphene. Examples include the introduction of a mobility edge [1][2][3][4], and the opening of a band gap and fluorescence [5][6][7][8][9] in hydrogenated, oxygenated and fluorinated graphene. The atomic size of adatoms, their chemical bonding with graphene, and the unique dispersion of the graphene electrons make adatoms a unique type of defects that interact strongly with electrons in graphene [10,11]. This interaction may offer an effective way to induce local

No abstract

Early detection and isolation of circulating tumor cells (CTCs) can provide helpful information for diagnosis, and functional readouts of CTCs can give deep insight into tumor biology. In this work, we presented a new strategy for simple isolation and release of CTCs using engineered nanobioprobes. The nanobioprobes were constructed by Ca(2+)-assisted layer-by-layer assembly of alginate onto the surface of fluorescent-magnetic nanospheres, followed by immobilization of biotin-labeled anti-EpCAM. As-prepared anti-EpCAM-functionalized nanobioprobes were characterized with integrated features of anti-EpCAM-directed specific recognition, fluorescent magnetic-driven cell capture, and EDTA-assisted cell release, which can specifically recognize 10(2) SK-BR-3 cells spiked in 1 mL of lysed blood or human whole blood samples with 89% and 86% capture efficiency, respectively. Our proof-of-concept experiments demonstrated that 65% of captured SK-BR-3 cells were released after EDTA treatment, and nearly 70% of released SK-BR-3 cells kept their viability, which may facilitate molecular profiling and functional readouts of CTCs.