Photo-Induced Click Chemistry for DNA Surface Structuring by Direct Laser Writing.

Oligonucleotides containing photo-caged dienes were prepared and shown to react quantitatively in a light-induced Diels-Alder cycloaddition with functional maleimides in aqueous solution within minutes. Due to its high yield and fast rate, the reaction was exploited for DNA surface patterning with sub-micrometer resolution employing direct laser writing (DLW). Functional DNA arrays were written by direct laser writing (DLW) in variable patterns, which were further encoded with fluorophores and proteins through DNA directed immobilization. This mild and efficient light-driven platform technology holds promise for the fabrication of complex bioarrays with sub-micron resolution.

Star polymer synthesis viaλ-orthogonal photochemistry.

We introduce a light induced sequence enabling λ-orthogonal star polymer formation via an arms-first approach, based on an α,ω-functional polymer carrying tetrazole and o-methyl benzaldehyde moieties, which upon irradiation can readily undergo cycloaddition with a trifunctional maleimide core. Depending on the wavelength, the telechelic strand can be attached to the core at either photo-reactive end.

Wavelength selective polymer network formation of end-functional star polymers.

A wavelength selective technique for light-induced network formation based on two photo-active moieties, namely ortho-methylbenzaldehyde and tetrazole is introduced. The network forming species are photo-reactive star polymers generated via reversible activation fragmentation chain transfer (RAFT) polymerization, allowing the network to be based on almost any vinylic monomer. Direct laser writing (DLW) allows to form any complex three-dimensional structure based on the photo-reactive star polymers.

Light-driven nitrile imine-mediated tetrazole-ene cycloaddition as a versatile platform for fullerene conjugation.

An efficient methodology for modular fullerene functionalization via the photo-induced nitrile imine-mediated tetrazole-ene cycloaddition (NITEC) is introduced. The versatility and platform character of the method is illustrated by the light-driven reaction of fullerenes with small molecule, polymeric and surface-immobilized tetrazoles. The efficient fullerene conjugation is evidenced via mass spectrometric techniques.

Photochemical Design of Functional Fluorescent Single-Chain Nanoparticles.

We report the facile ambient temperature generation of size tunable and well-defined (pro)fluorescent single-chain nanoparticles (SCNPs) via the photoinduced nitrile imine intramolecular cross-ligation of linear precursor polymers, constituting a platform technology as novel imaging agents. A set of three linear precursor polymers (Mn ≈ 14000 g mol-1, D ≈ 1.25) was synthesized via nitroxide-mediated statistical copolymerization of styrene and 4-(chloromethyl)styrene (CMS), followed by a postpolymerization modification of the resulting copolymer installing protected maleimide (PG-Mal) as well as tetrazole (Tet) moieties. The tetrazole content (% Tet) along the lateral polymer chains was varied between 12 and 24% in order to preselect not only the size of the corresponding SCNPs, but also their fluorescence and reactive properties. Finally, the applicability of the profluorescent SCNPs for fluorescence labeling was demonstrated utilizing residual surface expressed Tet moieties on the SCNPs surface in a reaction with maleimide functional polymeric microspheres. The (pro)fluorescent single-chain nanoparticles were in-depth characterized by 1H NMR spectroscopy, dynamic light scattering (DLS), size exclusion chromatography (SEC), and atomic force microscopy (AFM), as well as UV/vis and fluorescence spectroscopy.

Access to intrinsically glucoside-based microspheres with boron affinity.

Intrinsically glucoside-based microspheres are prepared in olive oil via a water in oil inverse suspension polymerization. The microspheres are characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) microscopy, and X-ray photoelectron spectroscopy (XPS), evidencing the intrinsic glucose character of the spheres. A novel boronic acid fluorescent molecule was subsequently conjugated to the microspheres in an aqueous environment, exhibiting the spatial and uniform distribution of glucoside as well as the affinity of the microspheres to bind with boron, evidenced via fluorescence spectroscopy measurements.

A facile route to boronic acid functional polymeric microspheres via epoxide ring opening.

Boronic acid-functionalized microspheres are prepared for the first time via mild epoxide ring opening based on porous cross-linked polymeric microspheres (diameter ≈ 10 µm, porosity ≈ 1000 Å). Quantitative chemical analysis by XPS and EA evidences that there is a greater functionalization with boronic acid when employing a sequential synthetic method [1.7 atom% boron (XPS); 1.12 wt% nitrogen (EA)] versus a one-pot synthetic method [0.2 atom% boron (XPS); 0.60 wt% nitrogen (EA)] yielding grafting densities ranging from approximately 2.5 molecules of boronic acid per nm(2) to 1 molecule of boronic acid per nm(2), respectively. Furthermore, the boronic acid-functionalized microspheres are conjugated with a novel fluorescent glucose molecule demonstrating a homogeneous spatial distribution of boronic acid.

(Ultra)fast catalyst-free macromolecular conjugation in aqueous environment at ambient temperature.

Tailor-made water-soluble macromolecules, including a glycopolymer, obtained by living/controlled RAFT-mediated polymerization are demonstrated to react in water with diene-functionalized poly(ethylene glycol)s without pre- or post-functionalization steps or the need for a catalyst at ambient temperature. As previously observed in organic solvents, hetero-Diels-Alder (HDA) conjugations reached quantitative conversion within minutes when cyclopentadienyl moieties were involved. However, while catalysts and elevated temperatures were previously necessary for open-chain diene conjugation, additive-free HDA cycloadditions occur in water within a few hours at ambient temperature. Experimental evidence for efficient conjugations is provided via unambiguous ESI-MS, UV/vis, NMR, and SEC data.