Volume Holography: Novel Materials, Methods and Applications

This chapter aims to establish a link between material compositions, analytical methods and advanced applications for volume holography. It provides basics on volume holography, serving as a compendium on volume holographic grating formation, specific material requirements for volume holography and diffractive properties of the different types of volume holographic gratings. The particular significance of three‐dimensional optical structuring for the final optical functionality is highlighted. In this context, the interrelation between function and structure of volume holograms is investigated with view to research on and development of novel materials, methods and applications. Particular emphasis will be placed on analytical methods, assuming that they provide access for a deeper understanding of volume holographic grating formation, which appears to be prerequisite for the design of novel material systems for advanced applications

Nano-contact transfer with gold nanoparticles on PEG hydrogels and using wrinkled PDMS-stamps

In the present work, a soft lithographic process is used to create nanometer-sized line patterns of gold nanoparticles (Au NPs) on PEG-based hydrogels. Hereby nanometer-sized wrinkles on polydimethylsiloxane (PDMS) are first fabricated, then functionalized with amino-silane and subsequently coated with Au NPs. The Au NPs are electrostatically bound to the surface of the wrinkled PDMS. In the next step, these relatively loosely bound Au NPs are transferred to PEG based hydrogels by simple contacting, which we denote “nano-contact transfer”. Nano-patterned Au NPs lines on PEG hydrogels are thus achieved, which are of interesting potential in nano-photonics, biosensor applications (using SERS) and to control nanoscopic cell adhesion events.DFG, 325093850, Open Access Publizieren 2017 - 2018 / Technische Universität Berli

Surface Patterning of Gold Nanoparticles on PEG-Based Hydrogels to Control Cell Adhesion

We report on a versatile and easy approach to micro-pattern gold nanoparticles (Au NPs) on 8-arm poly(ethylene glycol)-vinyl sulfone thiol (8PEG-VS-SH) hydrogels, and the application of these patterned Au NPs stripes in controlling cell adhesion. Firstly, the Au NPs were patterned on silicon wafers, and then they were transferred onto reactive, multifunctional 8PEG-VS-SH hydrogels. The patterned, micrometer-sized Au NPs stripes with variable spacings ranging from 20 μm to 50 μm were created by our recently developed micro-contact deprinting method. For this micro-contact deprinting approach, four different PEG-based stamp materials have been tested and it was found that the triblock copolymer PEG-PPG-PEG-(3BC) stamp established the best transfer efficiency and has been used in the ongoing work. After the successful creation of micro-patterns of Au NPs stripes on silicon, the patterns can be transferred conveniently and accurately to 8PEG-VS-SH hydrogel films. Subsequently these Au NPs patterns on 8PEG-VS-SH hydrogels have been investigated in cell culture with murine fibroblasts (L-929). The cells have been observed to adhere to and spread on those nano-patterned micro-lines in a remarkably selective and ordered manner

Cell phenotypic changes of mouse connective tissue fibroblasts (L-929) to poly(ethylene glycol)-based gels

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Cellular responses to various gels fabricated by photoinitiated crosslinking using acrylated linear and multi-arm poly(ethylene glycol) (PEG)-based and poly(propylene glycol)-b-poly(ethylene glycol) precursors were investigated. While no protein adsorption and cell adhesion were observed on the hydrophilic PEG-based gels, protein adsorption and cell adhesion did occur on the more hydrophobic gel generated from the block copolymer precursor. Murine fibroblast viability on the poly(ethylene glycol)-based gels was studied in the course of 72 h and the results indicated no cytotoxicity. In a systematic study, extra- and intracellular metabolites of the murine fibroblasts cultured on these PEG-based gels were examined by GC-MS. Distinct intra- and extracellular changes in primary metabolism, namely amino acid metabolism, glycolysis and fatty acid metabolism, were observed. Cells cultured on the polymeric gels induced more intense intracellular changes in the metabolite profile by means of higher metabolite intensities with time in comparison to cells cultured on the reference substrate (tissue culture polystyrene). In contrast, extracellular changes of metabolite intensities were comparable.DFG, EXC 314, Unifying Concepts in Catalysi

Novel wet micro-contact deprinting method for patterning gold nanoparticles on PEG-hydrogels and thereby controlling cell adhesion

In the present work we introduce a novel method to create linear and rectangular micro-patterns of gold nanoparticles (Au NPs) on poly(ethylene glycol) (PEG) hydrogels. The strategy consists of removing Au NPs from defined regions of the silicon wafer by virtue of the swelling effect of the hydrogel. Using this method, which we denote as “Wet Micro-Contact Deprinting”, well-defined micro-patterns of Au NPs on silicon can be created. This resulting pattern is then transferred from the hard substrate to the soft surface of PEG-hydrogels. These unique micro- and nano-patterned hydrogels were cultured with mouse fibroblasts L929 cells. The cells selectively adhered on the Au NPs coated area and avoided the pure PEG material. These patterned, nanocomposite biointerfaces are not only useful for biological and biomedical applications, such as tissue engineering and diagnostics, but also, for biosensor applications taking advantage of surface plasmon resonance (SPR) or surface enhanced Raman scattering (SERS) effects, due to the optical properties of the Au NPs.DFG, 325093850, Open Access Publizieren 2017 - 2018 / Technische Universität Berli

Nano- and Micro-Patterning of Gold Nanoparticles on PEG- Based Hydrogels for Controlling Cell Adhesion

Gold nanoparticles (Au NPs) have unique and tunable size- and shape-dependent optical and chemical properties and little toxicity. In this chapter, we describe results on Au NPs employed as cell-binding entities at biomaterials’ interfaces. Hereby, Au NPs with different sizes and shapes were nano- or micro-patterned on the surface of poly(ethylene glycol) (PEG)-based hydrogels by using our recently developed patterning strategies based on soft lithography. These hybrid biomaterials can be applied in various biological or biomedical applications, such as for fundamental cell studies considering adhesion and migration, tissue engineering, drug delivery, or as biosensors by using surface plasmon resonance (SPR) or surface-enhanced Raman spectroscopy (SERS)

Blending PEG-based polymers and their use in surface micro-patterning by the FIMIC method to obtain topographically smooth patterns of elasticity

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.We have designed and fabricated a library of polyethylene glycol (PEG)-based polymer blends, including blends of two PEG-based polymers that are liquid at room temperature where the optimisation of the blending method allows for the incorporation of higher molecular-weight PEG-based polymers which are solid at room temperature. The absence of a solvent in these blends makes them perfect candidates for use in our recently developed Fill-Molding in Capillaries (FIMIC) patterning method. As our FIMIC samples have shown to be not completely smooth (a small topography up to several nanometers has been seen previously), and this is likely to affect the cellular behaviour, we have improved our technique in order to obtain virtually smooth samples that exhibit a pattern of elasticity only. It is demonstrated that, by taking advantage of the differential swelling of the pattern components, we can level out the undesired topographic difference. In particular, by employing blends of materials, (1) the swelling degree of each component can be fine-tuned to even out any topography and (2) the use of the same blends in the sample, yet with varying cross-linker amounts, ensures the swelling degree and elasticity change without changing the surface chemistry significantly. Genuine, binary patterns of elasticity can thus be fabricated, which are a great asset to study cell migration phenomena in systematic detail.DFG, EXC 314, Unifying Concepts in Catalysi

Micro-Patterning of PEG-Based Hydrogels With Gold Nanoparticles Using a Reactive Micro-Contact-Printing Approach

In this work a novel, relatively simple, and fast method for patterning of gold nanoparticles (Au NPs) on poly(ethylene glycol) (PEG)-based hydrogels is presented. In the hereby exploited reactive micro-contact printing (reactive-μ-CP) process, the surface of a micro-relief patterned PDMS-stamp is first functionalized with an amino-silane self-assembled monolayer (SAM), which is then inked with Au NPs. The stamp is subsequently brought into conformal contact with thiol-functionalized PEG-based hydrogel films. Due to the strong gold-thiol interactions the Au NPs are adequately and easily transferred onto the surfaces of these soft, multifunctional PEG hydrogels. In this way, defined μ-patterns of Au NPs on PEG hydrogels are achieved. These Au NPs patterns allow specific biomolecular interactions on PEG surfaces, and cell adhesion has been studied. Cells were found to effectively adhere only on Au NPs micro-patterns and to avoid the anti-adhesive PEG background. Besides the cell adhesion studies, these Au NPs μ-patterns can be potentially applied as biosensors in plasmon-based spectroscopic devices or in medicine, e.g., for drug delivery systems or photothermal therapies