Assessing polymer-surface adhesion with a polymer collection

Polymer modification plays an important role in the construction of devices, but the lack of fundamental understanding on polymer-surface adhesion limits the development of miniaturized devices. In this work, a thermoplastic polymer collection was established using the combinatorial laser-induced forward transfer technique as a research platform, to assess the adhesion of polymers to substrates of different wettability. Furthermore, it also revealed the influence of adhesion on dewetting phenomena during the laser transfer and relaxation process, resulting in polymer spots of various morphologies. This gives a general insight into polymer-surface adhesion and connects it with the generation of defined polymer microstructures, which can be a valuable reference for the rational use of polymers

A low-cost laser-based nano-3D polymer printer for rapid surface patterning and chemical synthesis of peptide and glycan microarrays

A low-cost laser-based printing setup is presented, which allows for the spot-wise patterning of surfaces with defined polymer nanolayers. These nanolayer spots serve as a “solid solvent,” embedding different chemicals, chemical building blocks, materials, or precursors and can be stacked on top of each other. By melting the spot pattern, the polymer-embedded molecules are released for chemical reaction. This enables researchers to quickly pattern a surface with different molecules and materials, mixing them directly on the surface for high-throughput chemical synthesis to generate and screen diverse microarray libraries. In contrast to expensive ink-jet or contact printing, this approach does not require premixing of inks, which enables in situ combinatorial mixing. Easy access and versatility of this patterning approach are shown by generating microarrays of various biomolecules, such as glycans for the first time, to screen interactions of antibodies and lectins. In addition, a layer-by-layer solid-phase synthesis of peptides directly on the microarray is presented. Amino acid–containing nanolayers are repeatedly laser-transferred and reacted with the functionalized acceptor surface in defined patterns. This simple system enables a reproducible array production, down to spot-to-spot distances of 100 μm, and offers a flexible and cheap alternative to expensive spotting robot technology

Laser-driven growth of structurally defined transition metal oxide nanocrystals on carbon nitride photoelectrodes in milliseconds

Fabrication of hybrid photoelectrodes on a subsecond timescale with low energy consumption and possessing high photocurrent densities remains a centerpiece for successful implementation of photoelectrocatalytic synthesis of fuels and value-added chemicals. Here, we introduce a laser-driven technology to print sensitizers with desired morphologies and layer thickness onto different substrates, such as glass, carbon, or carbon nitride (CN). The specially designed process uses a thin polymer reactor impregnated with transition metal salts, confining the growth of transition metal oxide (TMO) nanostructures on the interface in milliseconds, while their morphology can be tuned by the laser. Multiple nano-p-n junctions at the interface increase the electron/hole lifetime by efficient charge trapping. A hybrid copper oxide/CN photoanode with optimal architecture reaches 10 times higher photocurrents than the pristine CN photoanode. This technology provides a modular approach to build a library of TMO-based composite films, enabling the creation of materials for diverse applications

On-chip neo-glycopeptide synthesis for multivalent glycan presentation

Single glycan-protein interactions are often weak, such that glycan binding partners commonly utilize multiple, spatially defined binding sites to enhance binding avidity and specificity. Current array technologies usually neglect defined multivalent display. Laser-based array synthesis technology allows for flexible and rapid on-surface synthesis of different peptides. Combining this technique with click chemistry, we produced neo-glycopeptides directly on a functionalized glass slide in the microarray format. Density and spatial distribution of carbohydrates can be tuned, resulting in well-defined glycan structures for multivalent display. We probed the two lectins concanavalin A and langerin with different glycans on multivalent scaffolds, revealing strong spacing-, density-, and ligand-dependent binding. In addition, we could also measure the surface dissociation constant. This approach allows for a rapid generation, screening, and optimization of a multitude of multivalent scaffolds for glycan binding

Experimental Study of Liquid Interfaces with Compositional Gradients: Distortion & Rupture of Ultra-Thin Films and Other Effects

The topic of this thesis is the experimental investigation of evaporating thin films on planar solid substrates and the enrichment, the crystal growth and Marangoni flows near the three phase line in the case of partially wetting mixtures of volatile and non volatile liquids. In short, it deals with the properties of planar liquid films and with those of thin liquid sections near the three phase contact line. In both cases the liquid looses continuously one component by evaporation. One topic is the rupture behavior of ultra-thin films of binary mixtures of a volatile solvent and a nonvolatile solute. It is studied how the thickness at which the film ruptures is related to the solute crystallization at the liquid/substrate interface as soon as the solute reaches supersaturation. A universal relation between the rupture thickness and the saturation behaviour is presented. The second research subject are individual nanoparticles embedded in molecularly thin films at planar substrates. It is found that the nanoparticles cause an unexpectedly large film surface distortion (meniscus). This distortion can be measured quantitatively by conventional reflective microscopy although the nanoparticles are much smaller than the Rayleigh diffraction limit. Investigations with binary mixtures of volatile solvents and non-volatile solutes (polymers) aim at a better understanding/prediction of the final solute coverage, the time-resolved film thinning, the time-resolved solvent evaporation, and the evolution of the solute concentration within the thinning film. A quantiative theoretical description of the experimental findings is derived. Experiments of completely miscible binary mixtures of volatile liquids, which individually form continuous planar films show unexpectedly that films of mixtures are not necessarily continuous and planar. Rather, they may form surface undulations or even rupture. This is explained with surface Marangoni flows. A new method for the exceptionally fast fabrication (mm/min) of ultralong aligned diphenylalanin single crystals via dip casting is presented. It is shown how the specific evaporation conditions at the three phase line can be used for a controlled peptide crystal growth process. It is further demonstrated how the confinement inside a smalll capillary affects the peptide crystallization and how this can be understood (and used)