Honeycomb-patterned fluorescent films fabricated by self-assembly of surfactant-assisted porphyrin/polymer composites

Au Nanoparticles Immobilized on Honeycomb-Like Polymeric Films for Surface-Enhanced Raman Scattering (SERS) Detection

We have successfully developed novel surface-enhanced Raman scattering (SERS) substrates with three-dimensional (3D) porous structures for effectively improving the sensitivity and reproducibility of SERS, which can rapidly detect small molecules (rhodamine 6G as an example). Periodical arrays of the honeycomb-like substrates were fabricated by self-assembling polyurethane-co-azetidine-2,4-dione (PU-PAZ) polymers. PU-PAZ comprising amphiphilic dendrons could stabilize the phase separation between the water droplets and polymer solution, and then organize into regular porous structures during the breath figure method. Subsequently, SERS substrates were fabricated by immobilizing gold nanoparticles (AuNPs) onto the honeycomb-like films with various 3D porous structures, controlled by the different PU-PAZ concentrations and relative humidities. Results show that surface enhancement factors of honeycomb-like substrates were 20 times higher than that of flat-film substrates (control group) due to enormous hot-spots resonance effects by the 3D porous structure, verified through Raman mapping at various positions of the z-axis. Furthermore, the particle size effects were evaluated by immobilized 12 and 67 nm of AuNPs on the honeycomb-like substrates, indicating larger AuNPs could induce more pronounced hot-spots effects. The generation of hot-spots resonance to enhance Raman intensity is strongly dependent on the diameter of AuNPs and the pore size of the honeycomb-like and 3D porous substrates for label-free and rapid SERS detection.

Micropatterned fabrication of chitosan-based thermoresponsive membranes for improving cell adhesion and gene expression

A simple, rapid, and economical method to fabricate micropatterned thermoresponsive chitosan membranes was developed. Porous polystyrene films were prepared by liquid-induced phase separation. The size of pores on polystyrene films could be regulated by adjusting the composition of coagulation bath and changing the solvent evaporation rate. Subsequently, chitosan-based thermoresponsive membranes with island protrusions were fabricated using porous polystyrene films as templates. The effects of the micropatterns on the behaviors of mouse fibroblast L929 were investigated. The presence of micropatterns altered the cell cycle distribution and enhanced the gene expression of cyclin D1 and integrin β1. The micro-convex surface could promote the adhesion and proliferation of L929 cells. These results provided valuable guidance to design appropriate topographic surfaces for tissue engineering applications.

Tailored honeycomb-like polymeric films based on amphiphilic poly(urea/malonamide) dendrons

A series of hydrogen bond-rich poly(urea/malonamide) dendrons were utilized as surfactants to facilitate the formation of honeycomb-like porous structures from the breath figure (BF) process.

Synthesis of carbon microrings using polymer blends as templates

Carbon microrings were produced using a template based on phase separation of amylose/pentadecyl phenol (PDP)/dimethyl sulfoxide (DMSO) mixtures.

Porphyrinated polyimide honeycomb films with high thermal stability for HCl gas sensing

Thermally stable films with ordered pores are fabricated from porphyrinated polyimides and they exhibit excellent property in HCl gas sensing.

Porphyrin-based honeycomb films and their antibacterial activity

Micrometer-sized porous honeycomb-patterned thin films based on hybrid complexes formed via electrostatic interaction between Mn(III) meso-tetra(4-sulfonatophenyl) porphine chloride (an acid form, {MnTPPS}) and dimethyldioctadecylammonium bromide (DODMABr). The morphology of the microporous thin films can be well regulated by controlling the concentration of MnTPPS-DODMA complexes, DODMABr, and polystyrene (PS), respectively. The formation of the microporous thin films was largely influenced by different solvents. The well-ordered microporous films of MnTPPS-DODMA complexes exhibit a more efficient antibacterial activity under visible light than those of hybrid complexes of nanoparticles modified with DODMABr, implying that well-ordered microporous films containing porphyrin composition can improve photochemical activity and more dominance in applications in biological medicine fields.

Mechanism of peripheral substituent effects on adsorption-aggregation behaviors of cationic porphyrin dyes on tungsten(VI) oxide nanocolloid particles

The adsorption and aggregation behaviors of the cationic porphyrin derivatives such as 5,10,15,20-tetrakis(4-pyridyl)porphyrin [TPyP], 5,10,15,20-tetrakis(N-methyl-4-pyridyl)porphyrin [TMPyP], 5,10,15,20-tetrakis(N-ethyl-4-pyridyl)porphyrin [TEPyP], and 5,10,15,20-tetrakis(N-n-propyl-4-pyridyl)porphyrin [TPPyP] (hereafter called "TPyP derivatives") in the tungsten(VI) oxide (WO3) colloid aqueous solution at weak acidic pH were studied by UV-vis spectroscopy. The TPyP derivatives were strongly adsorbed as monolayer onto the WO3 surface via the electrostatic interaction between their peripheral cationic substituents and negatively surface-charged WO3 colloid particles, and most of the ones adsorbed eventually formed J-type dimers aligned in the head-to-tail fashion. These different dimerization states were effectively analyzed by the change of ratios among the intensities of exciton split Soret bands (H- and J-bands). Judging from the exciton coupling theory and adsorption measurements, we concluded that the J-dimer geometry of the TPyP derivatives adsorbed on the WO3 colloid particle surface is strongly dependent on the presence and difference of peripheral substituents. The results described here indicate a new and promising way of designing surface supramolecular structures combination of two principles, the self-association of organic dyes, and the steric repulsive interaction between the peripheral substituents and the inorganic semiconductor surfaces.