Development of Ag/AgX (X=Cl, I) nanoparticles toward antimicrobial, UVprotectedand self-cleanable viscose fibers

In situ synthesis of Ag/AgX nanoparticles (NPs) onto viscose fibers adds new functionalities and broadens theirapplications. In this study, Ag/AgX (X=Cl, I) NPs were in situ synthesized onto viscose fibers to impart brilliantcolors, UV-protection, antimicrobial, self-cleaning, and photocatalytic properties. The AgX NPs were depositedon the fibers by ultrasonic irradiation, while Ag-NPs were formed by photoreduction of excess Ag+ ions underUV irradiation. The Ag/AgX NPs-loaded onto viscose fibers endowed with pale yellow for Ag/AgI and palepurple/violet for Ag/AgCl. The colored viscose fibers showed excellent antimicrobial activity against Escherichiacoli (gram-negative), Staphylococcus aureus (Gram positive), and Candida Albican. The Ag/AgX/viscose fiber alsoshowed excellent photocatalytic and self-cleaning activity toward degradation of methylene blue

Colored, photocatalytic, antimicrobial and UV-protected viscose fibers decorated with Ag/Ag2CO3 and Ag/Ag3PO4 nanoparticles

Surface modification of textile fibers with nanoparticles (NPs) has been widely investigated for multiple different uses. Herein, a simple and highly efficient technique was developed to impart multifunctional properties to viscose rayon fibers by in situ adding Ag/Ag2CO3 and Ag/Ag3PO4 NPs. Firstly, Ag2CO3 and Ag3PO4 NPs were precipitated via ultrasonic irradiation synthesis. Subsequently, Ag NPs were synthesized in situ by photoreduction of the excess Ag+ ions under UV-irradiation. The viscose rayon fibers decorated with Ag/Ag2CO3 and Ag/Ag3PO4 NPs showed excellent photocatalytic activity, and were protective against pathogenic microorganisms and UV radiation. Additionally, the modified viscose rayon fibers exhibited different colors ranging from pale yellow for Ag/Ag2CO3/viscose fibers to pale purple/violet for Ag/Ag3PO4/viscose fibers

Towards multifunctional cellulosic fabric: UV photo-reduction and in-situ synthesis of silver nanoparticles into cellulose fabrics

Herein, the highly multifunctional cotton fabric surfaces were designed with excellent coloration, UV-protection function, and antimicrobial activity. These multifunctional functions were developed by in-situ synthesis of silver nanoparticles (Ag NPs) into the cotton fabric surface using a simple green one-pot “UV-reduction” method. Cotton fabrics were pretreated with non-anionic detergent, immersed into alcoholic silver nitrate solution (concentration ranging from 100 to 500 ppm), squeezed to remove excess solution and then exposed to UV-irradiation (range 320–400 nm) for 1 h. The influence UV-irradiation on the thermal, chemical, optical and biological properties of the cotton fabric surface was discussed in details. The UV-irradiation promotes reducing of Ag+ ions and the cotton fabrics act as seed medium for Ag NPs formation by “heterogeneous nucleation”. Increasing Ag+ concentration (from 100 to 500 ppm) results in Ag NPs of particle size (distribution) of 50–100 nm. Interestingly, the Ag NPs exhibited different localized surface Plasmon resonance properties causing a coloration of the cotton fabrics with different color shades ranging from bright to dark brown with excellent color fastness properties. The treated cotton fabrics also show high protecting functions against UV-transmission (reduction of 65%) and Escherichia coli growth (99%). The side-effects of the UV-reduction process are further investigated

Impact of Laser Structuring on Medical-Grade Titanium: Surface Characterization and In Vitro Evaluation of Osteoblast Attachment

Improved implant osteointegration offers meaningful potential for orthopedic, spinal, and dental implants. In this study, a laser treatment was used for the structuring of a titanium alloy (Ti6Al4V) surface combined with a titanium dioxide coating, whereby a porous surface was created. The objective was to characterize the pore structure shape, treatment-related metallographic changes, cytocompatibility, and attachment of osteoblast-like cells (MG-63). The treatment generated specific bottleneck pore shapes, offering the potential for the interlocking of osteoblasts within undercuts in the implant surface. The pore dimensions were a bottleneck diameter of 27 µm (SD: 4 µm), an inner pore width of 78 µm (SD: 6 µm), and a pore depth of 129 µm (SD: 8 µm). The introduced energy of the laser changed the metallic structure of the alloy within the heat-affected region (approximately 66 µm) without any indication of a micro cracking formation. The phase of the alloy (microcrystalline alpha + beta) was changed to a martensite alpha phase in the surface region and an alpha + beta phase in the transition region between the pores. The MG-63 cells adhered to the structured titanium surface within 30 min and grew with numerous filopodia over and into the pores over the following days. Cell viability was improved on the structured surface compared to pure titanium, indicating good cytocompatibility. In particular, the demonstrated affinity of MG-63 cells to grow into the pores offers the potential to provide significantly improved implant fixation in further in vivo studies

Biomimetic PDMS-hydroxyurethane terminated with catecholic moieties for chemical grafting on transition metal oxide-based surfaces

The aim of this work was to synthesize a non-isocyanate poly(dimethylsiloxane) hydroxyurethane with biomimetic terminal catechol moieties, as a candidate for inorganic and metallic surface modification. Such surface modifier is capable to strong lyattach onto metallic and inorganic substrates forming layers and, in addition, providing water-repellent surfaces. The non-isocyanate route is based on carbon dioxide cycloaddition into bis-epoxide, resulting in a precursor bis(cyclic carbonate)-polydimethylsiloxane(CCPDMS), thus fully replacing isocyanate in the manufacture process. A biomimetic approach was chosen with the molecular composition being inspired by terminal peptides present in adhesive proteins of mussels, like Mefp (Mytilus edulis foot protein), which bear catechol moieties and are strong adhesives even under natural and saline water. The catechol terminal groups were grafted by aminolysis reaction into a polydimethylsiloxane backbone. The product, PDMSUr-Dopamine, presented high affinity towards inhomogeneous alloy surfaces terminated by native oxide layers as demonstrated by quartz crystal microbalance (QCM-D), as well as stability against desorption by rinsing with ethanol. As revealed by QCM-D, X-ray photoelectron spectroscopy (XPS) and computational studies, the thickness and composition of the resulting nanolayers indicated an attachment of PDMSUr-Dopamine molecules to the substrate through both terminal catechol groups, with the adsorbate exposing the hydrophobicPDMS backbone. This hypothesis was investigated by classical molecular dynamic simulation (MD) of pure PDMSUr-Dopamine molecules on SiO2surfaces. The computationally obtained PDMSUr-Dopamine assembly is in agreement with the conclusions from the experiments regarding the conformation of PDMSUr-Dopamine towards the surface. The tendency of the terminal catechol groups to approach the surface is in agreement with proposed model for the attachment PDMSUr-Dopamine. Remarkably, the versatile PDMSUr-Dopamine modifier facilitates such functionalization for various substrates such as titanium alloy, steel and ceramic surfaces

Functionalization of hydrophobic surfaces with antimicrobial peptides immobilized on a bio-interfactant layer

The design of functionalized polymer surfaces using bioactive compounds has grown rapidly over the past decade within many industries including biomedical, textile, microelectronics, bioprocessing and food packaging sectors. Polymer surfaces such as polystyrene (PS) must be treated using surface activation processes prior to the attachment of bioactive compounds. In this study, a new peptide immobilization strategy onto hydrocarbonaceus polymer surfaces is presented. A bio-interfactant layer made up of a tailored combination of laccase from trametes versicolor enzyme and maltodextrin is applied to immobilize peptides. Using this strategy, immobilization of the bio-inspired peptide KLWWMIRRWG-bromophenylalanine-3,4- dihydroxyphenylalanine-G and KLWWMIRRWG-bromophenylalanine-G on polystyrene (PS) was achieved. The interacting laccase layers allows to immobilize antimicrobial peptides avoiding the chemical modification of the peptide with a spacer and providing some freedom that facilitates different orientations. These are not strongly dominated by the substrate as it is the case on hydrophobic surfaces; maintaining the antimicrobial activity. Films exhibited depletion efficiency with respect to the growth of Escherichia coli bacteria and did not show cytotoxicity for fibroblast L929. This environmentally friendly antimicrobial surface treatment is both simple and fast, and employs aqueous solutions. Furthermore, the method can be extended to three-dimensional scaffolds as well as rough and patterned substrates

Urethanes PDMS-based: Functional hybrid coatings for metallic dental implants

In this study, we propose new polymeric coatings for metallic implants that impart biocompatibility and antibacterialfeatures to such surfaces. The starting material, poly(cyclic carbonate)-polydimethylsiloxane, wasprepared from carbon dioxide fixation and then sequentially reacted by aminolysis with an organoaminosilane,affording the formation of an urethanic polydimethylsiloxane-based material. Finally, a hybrid coating wasobtained by performing a sol-gel process on the metallic surfaces, catalyzed by phosphotungstic acid. We provideevidence that due to the polydimethylsiloxane segments governing the surface termination, the hybrid coatingsshow a hydrophobic character. Furthermore, due the presence of phosphotungstic acid in the upper surface, theadhesion of Gram-positive and Gram-negative bacteria is suppressed in 4 h of contact with aqueous bacterialcultures. In addition, the coatings presented a>70% cytocompatibility besides a low cytotoxicity, making theminteresting candidates as biocompatible materials and an alternative to avoiding the biofilm associated withbacterial infections