Controlling the optical creation of gold nanoparticles in a PVA matrix by direct laser writing

We report about the study on the physical features of gold nano-particles (GNPs) created by 2-photons photo-reduction Direct Laser Writing in a Poly-Vinyl Alcohol (PVA) matrix doped with HAuCl4. We drop cast a film of the PVA+ HAuCl4 onto a glass substrate, in which we create 1D gratings made by stripes of GNPs with a single laser sweep. We show that the stripe width increases with the laser power and the exposure time. We also analyse the influence of the exposure time over the created nano-particles size distribution and density and we show that by suitably adjusting the exposure time it is possible to maximize the frequency of a given diameter. By comparing the experimental results with a polymerization “voxel” model, we are able to evaluate the effective cross section for 2- photons absorption of our material

The effect of mesenchymal stem cell transplantation on the recovery of bladder and hindlimb function after spinal cord contusion in rats

<p>Abstract</p> <p>Background</p> <p>Mesenchymal stem cells are widely used for transplantation into the injured spinal cord in vivo model and for safety, many human clinical trials are continuing to promote improvements of motor and sensory functions after spinal cord injury. Yet the exact mechanism for these improvements remains undefined. Neurogenic bladder following spinal cord injury is the main problem decreasing the quality of life for patients with spinal cord injury, but there are no clear data using stem cell transplantation for the improvement of neurogenic bladder for in vivo studies and the clinical setting.</p> <p>The purpose of this study was to delineate the effect of human mesenchymal stem cell (hMSCs) transplantation on the restoration of neurogenic bladder and impaired hindlimb function after spinal cord contusion of rats and the relationship between neurotrophic factors such as brain derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) and bladder and hindlimb functions.</p> <p>Results</p> <p>Modified moderate contusion injury were performed on the thoracic spinal cord of Sprague-Dawley rats using MASCIS impactor and hMSCs, human fibroblasts or phosphate-buffered saline were transplanted into injured spinal cord 9 days after injury for hMSC and two control groups respectively. Ladder test showed more rapid restoration of hindlimb function in hMSC group than in control group, but Basso, Beattie, and Bresnahan score and coupling score were not different significantly among hMSC and two control groups. Neurogenic bladder was not improved in either group. ED1 positive macrophages were significantly reduced in hMSC group than in two control groups, but ELISA and RT-PCR studies revealed BDNF and NT-3 levels in spinal cord and bladder were not different among hMSC and two control groups regardless the experimental duration.</p> <p>Conclusion</p> <p>hMSC transplantation was effective in reducing inflammatory reaction after spinal cord contusion of rats but not sufficient to recover locomotor and bladder dysfunction. BDNF and NT-3 levels in the spinal cord and bladder were not increased 28 and 56 days after hMSC transplantation.</p

Self-Organization of Dipolar 4,4’-Disubstituted 2,2’-Bipyridine Metal Complexes into Luminescent Lamellar Liquid Crystals

Mononuclear cis-dichloro complexes, [(LMCl2)-M-n], with different metal centres (Pt-II, Ni-II, and Zn-II) and a series of palladium and platinum derivatives, [(LMX2)-M-2], in which chloride groups are replaced with iodide, bromide, and azide ligands, have been synthesized from 4,4'-disubstituted-2,2'-bipyridines. Upon complexation of these non-mesogenic ligands, the peculiar structural arrangement, characterized by intermolecular associations of the new derivatives, induces mesomorphism in most [(LMX2)-M-2] complexes, confirming the importance of coordination chemistry in metal-mediated formation of liquid crystals. Single crystal X-ray structures have been determined for dihexadecyl 2,2'-bipyridyl-4,4'-dicarboxylatopalladium and -zinc dichloride derivatives. Both the metal centres and the ancillary ligands have been varied to use dipole coupling as a tool to control molecular architecture: thermal, as well as spectroscopic properties, depend strongly upon molecular dipolar interactions. Tunable red and blue emitters based on Pd-II and Pt-II, both in solution and in the solid state, have been obtained

Synthesis, Mesomorphism, and Spectroscopic Characterization of Bis[4-(n-alkoxy)-5-(p-n-tetradecylphenylazo)]-Substituted(N,N’-Salicylidenediaminato)nickel(II) Complexes

The bis[4-(n-C(m)H(2m+1)O)-5-(p-C(14)H(29)C6H4N=N)]-substituted N,N'- salicylidenediamines H2[L(N)(m,14)] (N = 1: 1,2-diaminoethane; N = 2: 1,3- diaminopropane; N = 3: 1,3-diamino-2,2-dimethylpropane; m = 6 or 18) have been synthesized. Both the N = 2 and 3 series of compounds display a smectic C (SmC) mesophase, with clearing points well below 100 °C. By treating the H2[L(N)(m,14)] ligands with an Ni(II) salt, liquid crystalline mononuclear complexes with 'unconventional' (lateral-tailed) molecular shape form. These Ni[L(N)(m, 14)] complexes, showing nematic and smectic disordered phases, are stable over a quite large temperature range and have been characterized by different spectroscopic techniques. The newly synthesized mesogens exhibit lower transition temperatures and higher thermal stability than homologous complexes Ni[L(N)(14)] with a 'conventional' rod-like molecular geometry

Self-Organization of Dipolar 4,4′-Disubstituted 2,2′-Bipyridine Metal Complexes into Luminescent Lamellar Liquid Crystals

Mononuclear cis-dichloro complexes, [(LMCl2)-M-n], with different metal centres (Pt-II, Ni-II, and Zn-II) and a series of palladium and platinum derivatives, [(LMX2)-M-2], in which chloride groups are replaced with iodide, bromide, and azide ligands, have been synthesized from 4,4'-disubstituted-2,2'-bipyridines. Upon complexation of these non-mesogenic ligands, the peculiar structural arrangement, characterized by intermolecular associations of the new derivatives, induces mesomorphism in most [(LMX2)-M-2] complexes, confirming the importance of coordination chemistry in metal-mediated formation of liquid crystals. Single crystal X-ray structures have been determined for dihexadecyl 2,2'-bipyridyl-4,4'-dicarboxylatopalladium and -zinc dichloride derivatives. Both the metal centres and the ancillary ligands have been varied to use dipole coupling as a tool to control molecular architecture: thermal, as well as spectroscopic properties, depend strongly upon molecular dipolar interactions. Tunable red and blue emitters based on Pd-II and Pt-II, both in solution and in the solid state, have been obtained

Organometallic red-emitting chromophores: a computational and experimental study on cyclometallated nile red complexes of palladium(II) and platinum(II) acetylacetonates and hexafluoroacetylacetonates

A comparative photophysical, electrochemical and computational study of a series of Nile Red cyclopalladated and newly synthesised cycloplatinated complexes is reported. All complexes are luminescent at room temperature and the emission properties are governed by the nature of the cyclometallated dye. However, the presence of platinum(II) as metal centre decreases severely the emission quantum yield, while the electronegativity of the ancillary hexafluoroacetylacetonato ligand enhanced the emission properties of the Nile Red complexes