Photopatterning of fluorescent host-guest carriers through pore activation of metal-organic framework single crystals.

Encoded fluorescent particles are fabricated through the selective uptake of dyes in photopatterned metal-organic framework single crystals. The concept is based on spatially controlled photochemical cleavage of pore-blocking pendant groups. Because of the crystalline and porous nature of the host, this approach enables guest uptake that is tunable and can be triggered though controlled irradiation.

Highly controllable direct femtosecond laser writing of gold nanostructures on titanium dioxide surfaces.

A highly reproducible and controllable deposition procedure for gold nanostructures on a titanium dioxide (TiO2) surface using femtosecond laser light has been demonstrated. This is realized by precisely focusing onto the TiO2 surface in the presence of a pure gold ion solution. The deposition is demonstrated both in dot arrays and line structures. Thanks to the multi-photon excitation, we observe that the deposition area of the nanostructures can be confined to a degree far greater than the diffraction limited focal spot. Finally, we demonstrate that catalytic activity with visible light irradiation is enhanced, proving the applicability of our new deposition technique to the catalytic field.

A non-invasive fluorescent staining procedure allows Confocal Laser Scanning Microscopy based imaging of Mycobacterium in multispecies biofilms colonizing and degrading polycyclic aromatic hydrocarbons.

To study the micro scale interactions of Mycobacterium with bacteria belonging to other genera by means of Confocal Laser Scanning Microscopy (CLSM), a procedure was developed to non-invasively and fluorescently stain Mycobacterium without compromising the signal produced by commonly used fluorescent reporter genes. The procedure makes use of the commercial non-specific nucleic acid stain Syto62 and was optimized to efficiently stain Mycobacterium cells in suspensions and biofilms. The staining procedure was found non-invasive towards overall cell viability, biofilm architecture and fluorescence signals emitted by other organisms expressing the fluorescent reporter genes gfp and dsRed. The procedure was successfully applied to visualize the comportment of the PAH-degrading Mycobacterium sp. VM552 in triple species biofilms containing, in addition to strain VM552, the GFP labeled PAH-degrading Sphingomonas sp. LH128-GFP and DsRed-labeled Pseudomonas putida OUS82(RF), and colonizing a glass substrate coated with phenanthrene crystals in flow chambers. CLSM imaging and subsequent appropriate image processing of the biofilms show that the comportment of strain Mycobacterium sp. VM552 was largely affected by the presence of the other organisms. The data support the value of the staining procedure to study ecological questions about micro scale behavior and niche occupation of Mycobacterium in multi-species systems.