The ability to control the charge-potential landscape at solid-liquid interfaces is pivotal to engineer novel devices for applications in sensing, catalysis and energy conversion. The isoelectric point (pI)/point of zero charge (pzc) of graphene plays a key role in a number of physico-chemical phenomena occurring at the graphene-liquid interface. Supported by theory, we present here a methodology to identify the pI/pzc of (functionalized) graphene, which also allows for estimating the nature and extent of ion adsorption. The pI of bare graphene (as-prepared, chemical vapor deposition (CVD)-grown) is found to be less than 3.3, which we can continuously modify up to 7.5 by non-covalent electrochemical attachment of aromatic amino groups, preserving the favorable electronic properties of graphene throughout. Modelling all the observed results with detailed theory, we also show that specific adsorption of ions and the substrate play only an ancillary role in our capability to tune the pI of graphene.

The presence of unwanted impurities in graphene is known to have a significant impact on its physical and chemical properties. Similar to carbon nanotubes, any trace metals present in graphene will affect the electrocatalytic properties of the material. Here, we show by direct electroanalysis that traces of copper still remain in transferred CVD (chemical vapor deposition)‐grown graphene (even after the usual copper etching process) and strongly influence its electrochemical properties. Subsequently, we use a real‐time electrochemical etching procedure to remove more than 90 % of the trace metal impurities, with a clear improvement in both the electrochemical and electronic‐transport properties of monolayer graphene.

The realization of graphene‐gold‐nanoparticle (G‐AuNP) hybrids is presented here through a versatile electrochemical approach, which allows the continuous tuning of the size and density of the particles obtainable on the graphene surface. Raman scattering from graphene, which is significantly enhanced in such hybrids, is systematically investigated as a function of the size and density of particles at the same location. In agreement with theory, it is shown that the Raman enhancement is tunable by varying predominantly the density of the nanoparticles. Furthermore, it is observed that the increase in Raman cross‐section and the strength of Raman enhancement varies as a function of the frequency of the vibrational mode, which may be correlated with the plasmonic fingerprint of the deposited AuNPs. In addition to this electromagnetic enhancement, support is found for a chemical contribution through the occurrence of charge transfer from the AuNPs onto graphene. Finally, G‐AuNP hybrids can be efficiently utilized as SERS substrates for the detection of specifically bound non‐resonant molecules, whose vibrational modes can be unambiguously identified. With the possibility to tune the degree of Raman enhancement, this is a platform to design and engineer SERS substrates to optimize the detection of trace levels of analyte molecules.

Monolayer graphene field-effect sensors operating in liquid have been widely deployed for detecting a range of analyte species often under equilibrium conditions. Here we report on the real-time detection of the binding kinetics of the essential human enzyme, topoisomerase I interacting with substrate molecules (DNA probes) that are immobilized electrochemically on to monolayer graphene strips. By monitoring the field-effect characteristics of the graphene biosensor in real-time during the enzyme-substrate interactions, we are able to decipher the surface binding constant for the cleavage reaction step of topoisomerase I activity in a label-free manner. Moreover, an appropriate design of the capture probes allows us to distinctly follow the cleavage step of topoisomerase I functioning in real-time down to picomolar concentrations. The presented results are promising for future rapid screening of drugs that are being evaluated for regulating enzyme activity.

O ver the last 15 years, the incidence of brain and spinal cord injuries among ice hockey players has increased. 1 A recent study involving players in junior leagues found that, in the 2009/10 hockey season, the incidence of game-related concussions was 7 times higher than the highest rate previously reported in 1998/99. 2 Brain injuries frequently result from aggressive bodychecking 3 and account for 15% of injuries among players 9-16 years of age. 4,5 In a study of a community-based hockey program involving boys aged 9-15 years, hostile aggressive acts, which have an intention to do harm, 6 were the primary cause of injury in one-third of games in which an injury resulted.7 Among high school students in Minnesota who played varsity ice hockey, those who played to relieve aggression were 4 times more likely than other players to experience a concussion.8 These findings highlight the association between aggressive behaviour and injury in ice hockey. However, little is known about what can be done to reduce this behaviour to create a safer environment for the sport.Existing reviews about reducing injury in sport have primarily assessed equipment or risk factors associated with injury.9−11 Recent systematic reviews highlighted the risks of bodychecking and renewed calls for policies to disallow bodychecking among youth playing ice hockey. 3,12 We conducted a systematic review to assess the effectiveness of interventions designed to reduce aggressive acts and related injuries among ice hockey players. We were particularly interested in evaluating the effectiveness of rule changes, educational interventions and behavioural modification in reducing aggressive acts and related injuries. Methods Data sourcesWe searched 8 electronic databases for potentially relevant articles published from the time

We present a contactless strategy based on bipolar electrochemistry for the local chemical modification of monolayer graphene sheets supported on a substrate. Specifically, peripheral graphene regions are directly modified by copper nanoparticles, the characteristics of which are controllable through the bipolar deposition parameters. This functionalization route provides access to hybrid monolayer graphene modified, for example, with two different metals on opposing peripheries. The presented strategy constitutes a new way to functionalize graphene and an avenue for systematically studying bipolar electrochemistry at the nanoscale.

Chemical functionalization of carbon nanotubes (CNTs) and graphene allows for fine-tuning their physical and chemical properties to realize fascinating new fundamental phenomena as well as exotic applications. A primary challenge in such endeavors is the need to identify the chemical nature of attached functionalities at a single-nano-object level in a spatially resolved manner. Here we report the vibrational fingerprinting of functional groups that are attached to individual CNTs and graphene flakes. In order to achieve this, we decorate noncovalently functionalized CNTs and graphene with nanoparticles, which leads to the appearance of Raman peaks that can be correlated with the vibrational modes characteristic of the functional groups with diffraction-limited spatial resolution. The presented strategy is generic enough to be extended to other chemical modification routes on a range of nanostructures and hence will allow for rapid characterization of chemical modification of individual (semi)conducting nanostructures.

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