The adsorption behavior of fucoidan as well as chitosan derivatives (chitosan sulfate) on poly(ethylene terephthalate) (PET) model film surface was studied using the quartz crystal microbalance technique. These systems were chosen for this study due to their promising biocompatible properties. Moreover, fucoidan and chitosan sulfate have promising anticoagulant properties and represent an alternative to heparin treatment of vascular grafts. As a first step, PET foils were activated by alkaline hydrolysis to increase their hydrophilicity. From these foils, model PET films were prepared by the spin coating technique on a silica quartz crystal. The selected polysaccharides (chitosan, fucoidan, and chitosan sulfate) were adsorbed from aqueous solutions on the PET surfaces. The adsorption was monitored using a quartz crystal microbalance with a dissipation unit. The surface chemistry and morphology of the chitosan/fucoidan or chitosan/chitosan sulfate coated PET-H films was analyzed using XPS and AFM. It was found that chitosan/fucoidan films were thinner and more compressed, while in the case of chitosan/chitosansulfate, large amounts of chitosan sulfate were adsorbed, indicating a loose and thick adsorbed film.
COBISS.SI-ID: 13016086
Article presents a novel systematic approach to the fabrication of highly functionalized SiO2 nanoparticles used for the adsorption of heavy-metal ions. Almost monodispersed silica (SiO2) nanoparticles with narrow particle size distributions of around 85 ± 5 nm were formed using the Stöber process. The prepared SiO2 nanoparticles were successfully surface-treated by the covalent attachment of mercaptopropyl groups onto the surfaces of the SiO2 nanoparticles. A FTIR spectra and TEM/EDXS analysis confirmed the binding of the mercaptosilane molecules. The final results for the heavy-metal adsorption showed the strongest affinity within the following sequence Hg2+ (99.9%) ) Pb2+ (55.9%) ) Cd2+ (50.2%) ) Zn2+ (4%).
COBISS.SI-ID: 17236758
Photochromic organic dyes can be widely used in materials for optically rewritable data storage, photonic switches, memories, sensors, or actuators. In recent years photochromic materials based on nanoparticles became particularly focused, since they can be dispersed in colloidal aqueous suspensions or incorporated in thin films, avoiding problems of light scattering or shallow light penetration in bulk materials. Spiropyrans, spirooxazines and diarylethenes were by far the most researched photochromes in nanoparticulate systems. Great effort was made to investigate photochromic dyes incorporated into organic nanoparticles via self-assembly strategies, covalent linkage or dispersion of the molecular species in polymers (doping). Nanoparticles composed of solely photochromic dyes were prepared by laser ablation and reprecipitation techniques. Photochromic dyes were microencapsulated by self-assembly, soap free-, emulsion/ microemulsion/miniemulsion or free radical- (co)polymerization. Sol-gel processing from silane precursors to poly(organo)siloxane matrix is a common method to synthesize doped or core-shell photochromic organogels. Colored forms of some photochromes display fluorescence; however, a more effective strategy for fluorescence modulation with photochromic molecules is integrating them, covalently or noncovalently, with a separate fluorophore in the same nanoparticles. These photoresponsive nanoparticles may find applications particularly in biological fields such as cell labelling and bioimaging. The purpose of this review is to summarize the preparation methods of organic nanoparticles containing photochromic dyes and to investigate their typical properties derived from their nanoparticulate character.
COBISS.SI-ID: 17107990
Two different lithographic techniques for the patterning of thin biopolymer films are developed. The first method is based on using a microstructured elastomeric mold for the structuring of thin films of regenerated cellulose. The thin films are manufactured by spin-coating of trimethylsilyl cellulose (TMSC) and subsequent regeneration. The microchannels formed by the mold and the cellulose film are filled with a cellulase solution by capillary action. In the areas exposed to the enzyme solution, the cellulose film is digested, whereas the area in contact with the mold is protected from the enzymatic activity. Optical thickness measurements, atomic force microscopy and fluorescent staining confirm a successful patterning of cellulose on several substrates by this method. The second method is based on the structured regeneration of thin TMSC films. TMSC surfaces are protected with metal masks and exposed to vapors of hydrochloric acid. These treatments result in hydrophilic cellulose structures surrounded by hydrophobic TMSC with differing physicochemical properties. Treatments of the obtained structures with cellulases allow the selective removal of pure cellulose, whereas a TMSC pattern remains on the surface. These TMSC can be regenerated back to pure cellulose by treatments with vapors of hydrochloric acid. The developed methods allow the effective fabrication of micropatterned biopolymer thin films suitable for further functionalization and application in, e.g., bioanalytical devices. This is shown by the immobilization and detection of single-stranded DNA on structured cellulose surfaces. Owing to the versatility of both patterning approaches the methods can be further extended to other combinations of substrates and enzymes.
COBISS.SI-ID: 16217878
A system of permanent magnets, similar to those used for scale prevention during water processing, was tested as an alternative to induce some improvements during the textile laundering procedure. In this comparative study, four sets of 25 runs of standard laundering were performed on white cotton under repeatable conditions: a set washed only with tap water, then with added standard IEC detergent, a set with magnetically treated water without the detergent, and then a set in a combination of both. Samples were analyzed on texture morphology by scanning electron microscopy, mineral fouling by X-ray diffractometry, and fabric characteristics, as prescribed by the standard procedure for the laundering effects' evaluation, i.e. dimensional change, breaking-strength, incineration residue, and color characteristics. It was indicated that magnetic water treatment modified the detergency and the mineral fouling, resulting in increased whiteness of cotton. It also slightly increased the reduction in the breaking strength, but this was still inside the standard quality requirements.
COBISS.SI-ID: 16816150