Base-washed graphene-oxide which has been sequentially-modified by thiol-epoxy chemistry, results in materials with ice-nucleation activity. The role of hydro-philic/phobic grafts and polymers was evaluated with the most potent functioning at just 0.25 wt %. These 2-D hybrid materials may find use in cryopreservation and fundamental studies on ice formation.The formation and growth of ice crystals presents problems in many fields from aerospace to cell cryopreservation to the automotive industry. Whilst ice formation is thermodynamically preferred below 0 °C, there exists a large barrier to this, such that pure water undergoes homogenous nucleation at ~ − 40 °C. For nucleation to occur above this temperature, a nucleator is necessary. In the environment, nucleators have been identified including dust,1 minerals, birch and conifer pollen2 and recently a species of fungus was found to be a potent nucleator.3 Ice nucleating proteins also exist in living species,4 for example Pseudomonas syringae produce ice nucleating proteins to promote frost formation on plant leaves, to release nutrients for feeding.5 However, the mechanisms of ice nucleation are not understood, and remain a significant challenge for modelling and theory.6,7 A key barrier to this understanding is the lack of sequentially modified materials to enable structure-activity relationships to be drawn. The few known nucleators are insoluble, inorganics such as kaolinite8 or bacterial proteins. Synthetic ice nucleators could play a key role in e.g. cellular cryopreservation, where control over the exact nucleation temperature could improve reproducibility in the cryopreservation process.9 In the past few years, significant progress has been made in the development of synthetic materials for ice recrystallization inhibition (IRI) -the growth of pre-formed ice crystals as mimics of antifreeze proteins (which sometimes, but not always, can influence ice nucleation also Considering the above, we hypothesised that the surface modification of base-washed graphene oxide would provide a versatile template to evaluate the potential of 2-dimensional carbon nanomaterials as ice-nucleating materials and also to provide a versatile scaffold to enable the role of surface chemistry to be probed. Base-washed GO (bwGO) was prepared using established methods16 to generate a 'clean' surface bearing epoxy groups available for orthogonal conjugation to thiols. For the surface modification, a small library of small molecule thiols was chosen, to give a range of hydrophilic/phobic functionalities. Watersoluble polymers with thiol-termini were also synthesised using RAFT (reversible addition fragmentation -transfer) polymerization. RAFT not only enables access to functional polymers of defined chain length and dispersity, but also introduces a thio-carbonyl at the ω-end-group, which can be reduced to a thiol. Using this method, poly(Nisopropylacrylamide), pNIPAM with degree of polymerization of 55 and 140 was synthesised, to use as a water soluble polymeric grafting age...

Carbohydrate–carbohydrate interactions are proposed to be biologically significant but have lower affinities than the well-studied carbohydrate–protein interactions. Here we introduce multivalent glyconanostructures where the surface expression of lactose can be triggered by an external stimulus, and a gold nanoparticle core enables colorimetric signal outputs to probe binding. Macromolecular engineering of a responsive polymer “gate” enables the lactose moieties to be presented only when an external stimulus is present, mimicking how nature uses enzymes to dynamically regulate glycan expression. Two different carbohydrate–carbohydrate interactions are investigated using this tool.

The monolithic integration of InAs(1-x)Sb(x) semiconductor nanowires on graphitic substrates holds enormous promise for cost-effective, high-performance, and flexible devices in optoelectronics and high-speed electronics. However, the growth of InAs(1-x)Sb(x) nanowires with high aspect ratio essential for device applications is extremely challenging due to Sb-induced suppression of axial growth and enhancement in radial growth. We report the realization of high quality, vertically aligned, nontapered and ultrahigh aspect ratio InAs(1-x)Sb(x) nanowires with Sb composition (xSb(%)) up to ∼12% grown by indium-droplet assisted molecular beam epitaxy on graphite substrate. Low temperature photoluminescence measurements show that the InAs(1-x)Sb(x) nanowires exhibit bright band-to-band related emission with a distinct redshift as a function of Sb composition providing further confirmation of successful Sb incorporation in as-grown nanowires. This study reveals that the graphite substrate is a more favorable platform for InAs(1-x)Sb(x) nanowires that could lead to hybrid heterostructures possessing potential device applications in optoelectronics.

Molybdenum (Mo)/4H-silicon carbide (SiC) Schottky barrier diodes have been fabricated with a phosphorus pentoxide (P 2 O 5 ) surface passivation treatment performed on the SiC surface prior to metallization. Compared to the untreated diodes, the P 2 O 5 -treated diodes were found to have a lower Schottky barrier height by 0.11 eV and a lower leakage current by two to three orders of magnitude. Physical characterization of the P 2 O 5 -treated Mo/SiC interfaces revealed that there are two primary causes for the improvement in electrical performance. First, transmission electron microscopy imaging showed that nanopits filled with silicon dioxide had formed at the surface after the P 2 O 5 treatment that terminates potential leakage paths. Second, secondary ion mass spectroscopy revealed a high concentration of phosphorus atoms near the interface. While only a fraction of these are active, a small increase in doping at the interface is responsible for the reduction in barrier height. Comparisons were made between the P 2 O 5 pretreatment and oxygen (O 2 ) and nitrous oxide (N 2 O) pretreatments that do not form the same nanopits and do not reduce leakage current. X-ray photoelectron spectroscopy shows that SiC beneath the deposited P 2 O 5 oxide retains a Si-rich interface unlike the N 2 O and O 2 treatments that consume SiC and trap carbon at the interface. Finally, after annealing, the Mo/SiC interface forms almost no silicide, leaving the enhancement to the subsurface in place, explaining why the P 2 O 5 treatment has had no effect on nickel-or titanium-SiC contacts.