Nano-colloid printing of functionalised PLA-b-PEO copolymers: Tailoring the surface pattern of adhesive motif and its effect on cell attachment

n this study, we investigate the preparation of surface pattern of functional groups on poly(lactide) (PLA) surfaces through the controlled deposition of core-shell self-assemblies based on functionalized PLA-b-PEO amphiphilic block copolymers from selective solvents. Through grafting RGDS peptide onto the functionalized copolymer surface, the presented approach enables to prepare PLA surfaces with random and clustered spatial distribution of adhesive motifs. The proposed topography of the adhesion motif was proved by atomic force microscopy techniques using biotin-tagged RGDS peptide grafted on the surface and streptavidin-modified gold nanospheres which bind the tagged RGDS peptides as a contrast agent. The cell culture study under static and dynamic conditions with MG63 osteosarcoma cell line showed that the clustered distribution of RGDS peptides provided more efficient initial cell attachment and spreading, and resistance to cell detachment under dynamic culture compared to randomly distributed RGDS motif when with the same average RGDS peptide concentration

Photo-induced functionalization of spherical and planar surfaces via caged thioaldehyde end-functional polymers

The synthesis and application of a novel reversible addition-fragmentation chain transfer (RAFT) agent carrying a photocaged thioaldehyde moiety is described (λmax = 355 nm). RAFT polymerization of styrene, dimethylacrylamide and a glycomonomer is evidenced (3600 g mol-1 ≤ Mn ≤ 15 000 g mol-1; 1.07 ≤ D{stroke} ≤ 1.20) with excellent end-group fidelity. The photogenerated thioaldehyde on the chain ends can undergo hetero Diels-Alder reactions with dienes as well as reactions with nucleophiles. The terminal photoreactive polymers are photografted to porous diene-reactive polymeric microspheres. The grafted particles are in-depth characterized via scanning electron microscopy, elemental analysis, X-ray photoelectron spectroscopy, and high resolution FT-IR microscopy, leading to a qualitative as well as quantitative image of the core-shell objects. Grafting densities up to 0.10 molecules nm-2 are reached. The versatility of the thioaldehyde ligation is evidenced by spatially resolved grafting of polystyrene onto nucleophilic groups present in poly (dopamine) (PDA)-coated glass slides and silicon wafers via two-photon direct laser writing (DLW) imaged by ToF-SIMS. The combination of thioaldehyde ligation, RAFT polymerization, and DLW allows for the spatially resolved grafting of a vast range of polymers onto various substrates in any desired pattern with sub-micrometer resolution. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

A facile avenue to conductive polymer brushes via cyclopentadiene-maleimide Diels-Alder ligation

Cyclopentadienyl end-capped poly(3-hexylthiophene) was employed to fabricate conductive surface tethered polymer brushes via a facile route based on cyclopentadiene-maleimide Diels-Alder ligation. The efficient nature of the Diels-Alder ligation was further combined with a biomimetic polydopamine- assisted functionalization of surfaces, making it an access route of choice for P3HT surface immobilization. © 2013 The Royal Society of Chemistry

Surface Grafting via Photo-Induced Copper-Mediated Radical Polymerization at Extremely Low Catalyst Concentrations

Surface-initiated photo-induced copper-mediated radical polymerization is employed to graft a wide range of polyacrylate brushes from silicon substrates at extremely low catalyst concentrations. This is the first time that the controlled nature of the reported process is demonstrated via block copolymer formation and re-initiation experiments. In addition to unmatched copper catalyst concentrations in the range of few ppb, film thicknesses up to almost 1 μm are achieved within only 1 h. Surface-initiated photo-induced copper-mediated radical polymerization is employed to graft a wide range of polyacrylate brushes from silicon substrates at extremely low catalyst concentrations. Block copolymer formation and re-initiation experiments evidence good control over the reaction. In addition to unmatched copper catalyst concentrations in the range of few ppb, film thicknesses up to almost 1 μm are achieved within only 1 h. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Hydrothermally grown molybdenum doped ZnO nanorod arrays. The concept of novel ultrafast nanoscintillator

Molybdenum doped ZnO was hydrothermally grown as the arrays of nanorods deposited onto the fused silica glass substrate. The molybdenum doping level varied from 1 to 30 %. The influence of Mo on the electronic and crystalline structure as well as luminescence and defects in the ZnO nanorods is under study of the bundle of experimental techniques complemented with density functional theory calculations. The tendency of Mo to create energy states within the bandgap of ZnO and their influence on the energy levels of native defects as well as excitons were proven by the synergy of experiment and theory. The improvement of the timing characteristics of the exciton- and zinc vacancy-related emission bands upon Mo doping (1–10 %) was observed. This paves the way for the defect engineering strategy in the search of effective and ultrafast scintillator with the improved light yield as well as compared to other materials. The new concept is based on the combination of the exciton and the defect emission. It is expected to have the potential of application in the detection of gamma rays implemented in time-of-flight positron emission tomography (TOFPET). The 20 and 30 % Mo doping levels resulted in the zinc molybdates creation strongly outnumbering ZnO nanorods