Wettability and Other Surface Properties of Modified Polymers

Surface wettability is one of the crucial characteristics for determining of a material’s use in specific application. Determination of wettability is based on the measurement of the material surface contact angle. Contact angle is the main parameter that characterizes the drop shape on the solid surface and is also one of the directly measurable properties of the phase interface. In this chapter, the wettability and its related properties of pristine and modified polymer foils will be described. The wettability depends on surface roughness and chemical composition. Changes of these parameters can adjust the values of contact angle and, therefore, wettability. In the case of pristine polymer materials, their wettability is unsuitable for a wide range of applications (such as tissue engineering, printing, and coating). Polymer surfaces can easily be modified by, e.g., plasma discharge, whereas the bulk properties remain unchanged. This modification leads to oxidation of the treated layer and creation of new chemical groups that mainly contain oxygen. Immediately after plasma treatment, the values of the contact angles of the modified polymer significantly decrease. In the case of a specific polymer, the strongly hydrophilic surface is created and leads to total spreading of the water drop. Wettability is strongly dependent on time from modification

Substrate Effects of Noble Metal Nanostructures Prepared by Sputtering

Cathode sputtering is a well-established technique for preparation of metal nanostructures. However, the substrate properties are very important in this process. On glass substrates, there is a difficulty with poor adhesion of the metal layers, but thanks to this, metal nanostructures can be produced using solid state dewetting process. Thin metal films on polymer substrates are strongly influenced by the surface properties of the polymers, which originate in the method of their preparation. A recent focus is direct sputtering of metal nanoparticles (NPs) into liquid substrates and their characterizations and applications. Polyethylene glycol (PEG) is one of the most commonly used liquid, which provides “stealth” character to nanostructures. Recent results in this area are reviewed in this chapter. PEGylated NPs could find application in drug delivery systems, therapy, imaging, biosensing, and tissue regeneration

Physicochemical Properties of Gold Nanostructures Deposited on Glass

Properties of gold films sputtered onto borosilicate glass substrate were studied. UV-Vis absorption spectra were used to investigate optical parameters. XRD analysis provided information about the gold crystalline nanostructure, the texture, and lattice parameter and biaxial tension was also determined by the XRD method. The surface morphology was examined by atomic force microscopy (AFM); chemical structure of sputtered gold nanostructures was examined by X-ray photoelectron spectroscopy (ARXPS). The gold crystallites are preferentially [111] oriented on the sputtered samples. Gold deposition leads to dramatic changes in the surface morphology in comparison to pristine glass substrate. Oxygen is not incorporated into the gold layer during gold deposition. Experimental data on lattice parameter were also confirmed by theoretical investigations of nanoclusters using tight-binding potentials

Improved Adhesion, Growth and Maturation of Vascular Smooth Muscle Cells on Polyethylene Grafted with Bioactive Molecules and Carbon Particles

High-density polyethylene (PE) foils were modified by an Ar+ plasma discharge and subsequent grafting with biomolecules, namely glycine (Gly), polyethylene glycol (PEG), bovine serum albumin (BSA), colloidal carbon particles (C) or BSA and C (BSA + C). As revealed by atomic force microscopy (AFM), goniometry and Rutherford Backscattering Spectroscopy (RBS), the surface chemical structure and surface morphology of PE changed dramatically after plasma treatment. The contact angle decreased for the samples treated by plasma, mainly in relation to the formation of oxygen structures during plasma irradiation. A further decrease in the contact angle was obvious after glycine and PEG grafting. The increase in oxygen concentration after glycine and PEG grafting proved that the two molecules were chemically linked to the plasma-activated surface. Plasma treatment led to ablation of the PE surface layer, thus the surface morphology was changed and the surface roughness was increased. The materials were then seeded with vascular smooth muscle cells (VSMC) derived from rat aorta and incubated in a DMEM medium with fetal bovine serum. Generally, the cells adhered and grew better on modified rather than on unmodified PE samples. Immunofluorescence showed that focal adhesion plaques containing talin, vinculin and paxillin were most apparent in cells on PE grafted with PEG or BSA + C, and the fibres containing α-actin, β-actin or SM1 and SM2 myosins were thicker, more numerous and more brightly stained in the cells on all modified PE samples than on pristine PE. An enzyme-linked immunosorbent assay (ELISA) revealed increased concentrations of focal adhesion proteins talin and vinculin and also a cytoskeletal protein β-actin in cells on PE modified with BSA + C. A contractile protein α-actin was increased in cells on PE grafted with PEG or Gly. These results showed that PE activated with plasma and subsequently grafted with bioactive molecules and colloidal C particles, especially with PEG and BSA + C, promotes the adhesion, proliferation and phenotypic maturation of VSMC

Application of a 2D Molybdenum Telluride in SERS Detection of Biorelevant Molecules

Two-dimensional (2D) transition-metal dichalcogenides have become promising candidates for surface-enhanced Raman spectroscopy (SERS), but currently very few examples of detection of relevant molecules are available. Herein, we show the detection of the lipophilic disease marker beta-sitosterol on few-layered MoTe2 films. The chemical vapor deposition (CVD)-grown films are capable of nanomolar detection, exceeding the performance of alternative noble-metal surfaces. We confirm that the enhancement occurs through the chemical enhancement (CE) mechanism via formation of a surface-analyte complex, which leads to an enhancement factor of approximate to 10(4), as confirmed by Fourier transform infrared (FTIR), UV-vis, and cyclic voltammetry (CV) analyses and density functional theory (DFT) calculations. Low values of signal deviation over a seven-layered MoTe2 film confirms the homogeneity and reproducibility of the results in comparison to noble-metal substrate analogues. Furthermore, beta-sitosterol detection within cell culture media, a minimal loss of signal over 50 days, and the opportunity for sensor regeneration suggest that MoTe2 can become a promising new SERS platform for biosensing.Peer reviewe

Chiral Metafilms and Surface Enhanced Raman Scattering For Enantiomeric Discrimination of Helicoid Nanoparticles

Chiral nanophotonic platforms provide a means of creating near fields with both enhanced asymmetric properties and intensities. They can be exploited for optical measurements that allow enantiomeric discrimination at detection levels greater than 6 orders of magnitude than is achieved with conventional chirally sensitive spectroscopic methods based on circularly polarized light. The optimal approach for exploiting nanophotonic platforms for chiral detection would be to use spectroscopic methods that provide a local probe of changes in the near field environment induced by the presence of chiral species. Here we show that surface enhanced Raman spectroscopy (SERS) is such a local probe of the near field environment. We have used it to achieve enantiomeric discrimination of chiral helicoid nanoparticles deposited on left and right-handed enantiomorphs of a chiral metafilm. Hotter electromagnetic hotspots are created for matched combinations of helicoid and metafilms (left-left and right-right), while mismatched combinations leads to significantly cooler electromagnetic hotspots. This large enantiomeric dependency on hotspot intensity is readily detected using SERS with the aid of an achiral Raman reporter molecule. In effect we have used SERS to distinguish between the different EM environments of the plasmonic diastereomers produced by mixing chiral nanoparticles and metafilms. The work demonstrates that by combining chiral nanophotonic platforms with established SERS strategies new avenues in ultrasensitive chiral detection can be opened

Preparation of Selective and Reproducible SERS Sensors of Hg²⁺ Ions via a Sunlight-Induced Thiol–Yne Reaction on Gold Gratings

In this contribution, we propose a novel functional surface-enhanced Raman spectroscopy (SERS) platform for the detection of one of the most hazardous heavy metal ions, Hg2+. The design of the proposed sensor is based on the combination of surface plasmon-polariton (SPP) supporting gold grating with the high homogeneity of the response and enhancement and mercaptosuccinic acid (MSA) based specific recognition layer. For the first time, diazonium grafted 4-ethynylphenyl groups have undergone the sunlight-induced thiol−yne reaction with MSA in the presence of Eosine Y. The developed SERS platform provides an extremely sensitive, selective, and convenient analytical procedure to detect mercury ions with limit of detection (LOD) as low as 10−10 M (0.027 µg/L) with excellent selectivity over other metals. The developed SERS sensor is compatible with a portable SERS spectrophotometer and does not require the expensive equipment for statistical methods of analysis

PTFE Based Multilayer Micro-Coatings for Aluminum AlMg3 Forms Used in Tire Production

The basic prerequisite for obtaining the coating of good quality is the production of a layer without the occurrence of surface defects. A possible solution to the occurrence of defects on the functional surface of the form is the application of a polytetrafluoroethylene (PTFE)-based coating. The coating helps to reduce surface roughness and “smooth” defects like pores and micro-shrinkage. For this reason, a new type and methodology of the coating were prepared to achieve more production cycles between the individual cleaning processes during the production of a tire. The subject of the study was the analysis of surface-applied micro-coatings, including the analysis of chemical composition by using energy-dispersive X-ray (EDX) and microstructure in the area of coatings. Detailed microstructural characterization of Alfipas 7818 and Alfiflon 39 and its imaging of surface structures were studied using atomic force microscopy. To examine the surface layer of the coatings, metallographic specimens of cross-sections (by means of a mold) were prepared and examined by light and electron microscopy. This new multilayer micro-coating with a thickness of 20–25 μm has been found to prevent form contamination during tire production and to extend production cycles by 200–400% between process cleanings. This finding was actually tested in the production of tires in the environment of a large manufacturing company

Effects of Bacterial Nanocellulose Loaded with Curcumin and Its Degradation Products on Human Dermal Fibroblasts

Bacterial nanocellulose has found applications in tissue engineering, in skin tissue repair, and in wound healing. Its large surface area enables the adsorption of various substances. Bacterial nanocellulose with adsorbed substances can serve as a substrate for drug-delivery of specific bioactive healing agents into wounds. In this study, we loaded a bacterial nanocellulose hydrogel with curcumin, i.e., an important anti-bacterial and healing agent, and its degradation products. These products were prepared by thermal decomposition of curcumin (DC) at a temperature of 180 °C (DC 180) or of 300 °C (DC 300). The main thermal decomposition products were tumerone, vanillin, and feruloylmethane. Curcumin and its degradation products were loaded into the bacterial nanocellulose by an autoclaving process. The increased temperature during autoclaving enhanced the solubility and the penetration of the agents into the nanocellulose. The aim of this study was to investigate the cytotoxicity and the antimicrobial activity of pure curcumin, its degradation products, and finally of bacterial nanocellulose loaded with these agents. In vitro tests performed on human dermal fibroblasts revealed that the degradation products of curcumin, i.e., DC 180 and DC 300, were more cytotoxic than pure curcumin. However, if DC 300 was loaded into nanocellulose, the cytotoxic effect was not as strong as in the case of DC 300 powder added into the culture medium. DC 300 was found to be the least soluble product in water, which probably resulted in the poor loading of this agent into the nanocellulose. Nanocellulose loaded with pure curcumin or DC 180 exhibited more antibacterial activity than pristine nanocellulose