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The endothelialization of synthetic surfaces applied as cardiovascular implant materials is an important issue to ensure the anti-thrombotic quality of a biomaterial. However, the rapid and constant development of a functionallycon-fluent endothelial cell monolayer is challenging. In order to investigate the compatibility of potential implant materials with endothelial cells several in vitro studies are performed. Here, glass and tissue culture plates (TCP) are often used as reference materials for in vitro pre-testing. However, a direct comparison of both substrates is lacking. Therefore, a comparison of study results is difficult, since results are often related to various reference materials. In this study, the endothelialization of glass and TCP was investigated in terms of adherence, morphology, integrity, viability and function using human umbilical vein endothelial cells (HUVEC). On both substrates an almost functionally confluent HUVEC monolayer was developed after nine days of cell seeding with clearly visible cell rims, decreased stress fiber formation and a pronounced marginal filament band. The viability of HUVEC was comparable for both substrates nine days after cell seeding with only a few dead cells. According to that, the cell membrane integrity as well as the metabolic activity showed no differences between TCP and glass. However, a significant difference was observed for the secretion of IL-6 and IL-8. The concentration of both cytokines, which are associated with migratory activity, was increased in the supernatant of HUVEC seeded on TCP. This result matches well with the slightly increased number of adherent HUVEC on TCP. In conclusion, these findings indicate that both reference materials are almost comparable and can be used equivalently as control materials in in vitro endothelialization studies.
BACKGROUND: Physical and chemical characteristics of implant materials determine the fate of long-term cardiovascular devices. However, there is still a lack of fundamental understanding of the molecular mechanisms occurring in the material-tissue interphase. In a previous study, soft covalently crosslinked poly(n-butyl acrylate) networks (cPnBA) were introduced as sterilizable, non-toxic and immuno-compatible biomaterials with mechanical properties adjustable to blood vessels. Here we study the influence of different surface treatments in particular oxygen plasma modification and fibrinogen deposition as well as a combinatorial approach on the adhesion and viability of fibroblasts. RESULTS: Compared to non-treated cPnBAs the advancing water-contact angles were found to be reduced after all surface modifications (p<0.05, each), while lowest values were observed after the combined surface treatment (OPT+FIB). The latter differed significantly from the single OPT and FIB. The number of adherent fibroblasts and their adherence behavior differed on both pristine cPnBA networks. The fibroblast density on cPnBA04 was 743 +/- 434 cells. mm(-2), was about 6.5 times higher than on cPnBA73 with 115 +/- 73 cells. mm(-2). On cPnBA04 about 20% of the cells were visible as very small, round and buckled cells while all other cells were in a migrating status. On cPnBA73, nearly 50% of fibroblasts were visible as very small, round and buckled cells. The surface functionalization either using oxygen plasma treatment or fibrinogen coating led to a significant increase of adherent fibroblasts, particularly the combination of both techniques, for both cPnBA networks. It is noteworthy to mention that the fibrinogen coating overruled the characteristics of the pristine surfaces; here, the fibroblast densities after seeding were identical for both cPnBAnetworks. Thus, the binding rather depended on the fibrinogen coating than on the substrate characteristics anymore. While the integrity of the fibroblasts membrane was comparable for both polymers, the MTS tests showed a decreased metabolic activity of the fibroblasts on cPnBA. CONCLUSION: The applied surface treatments of cPnBA successfully improved the adhesion of viable fibroblasts. Under resting conditions as well as after shearing the highest fibroblast densities were found on surfaces with combined post-treatment.
Remaining uremic toxins in the blood of chronic renal failure patients represent one central challenge in hemodialysis therapies. Highly porous poly(ether imide) (PEI) microparticles have been recently introduced as candidate absorber materials, which show a high absorption capacity for uremic toxins and allow hydrophilic surface modification suitable for minimization of serum protein absorption. In this work, the effects of extracts prepared from PEI microparticles modified by nucleophilic reaction with low molecular weight polyethylene imine (Pei) or potassium hydroxide (KOH), on human monocytic (THP-1) cells are studied. The obtained results suggested that the extracts of Pei and KOH modified PEI absorbers have no negative effect on THP-1 cell viability and do not initiate the critical differentiation towards macrophages. The extracts did not enhance transcript or protein levels of investigated proinflammatory markers in THP-1 cells, namely, TNF alpha, MCP1, IL6 and IL8. Based on these findings such modified PEI microparticles should be qualified for further pre-clinical evaluation i.e. in an in vivo animal experiment.
Breaking the Barrier
(2018)
Topical administration permits targeted, sustained delivery of therapeutics to human skin. Delivery to the skin, however, is typically limited to lipophilic molecules with molecular weight of < 500 Da, capable of crossing the stratum corneum. Nevertheless, there are indications protein delivery may be possible in barrier deficient skin, a condition found in several inflammatory skin diseases such as psoriasis, using novel nanocarrier systems. Methods: Water in water thermo-nanoprecipitation; dynamic light scattering; zeta potential measurement; nanoparticle tracking analysis; atomic force microscopy; cryogenic transmission electron microscopy; UV absorption; centrifugal separation membranes; bicinchoninic acid assay; circular dichroism; TNF alpha binding ELISA; inflammatory skin equivalent construction; human skin biopsies; immunohistochemistry; fluorescence microscopy; western blot; monocyte derived Langerhans cells; ELISA Results: Here, we report the novel synthesis of thermoresponsive nanogels (tNG) and the stable encapsulation of the anti-TNFa fusion protein etanercept (ETR) (similar to 150 kDa) without alteration to its structure, as well as temperature triggered release from the tNGs. Novel tNG synthesis without the use of organic solvents was conducted, permitting in situ encapsulation of protein during assembly, something that holds great promise for easy manufacture and storage. Topical application of ETR loaded tNGs to inflammatory skin equivalents or tape striped human skin resulted in efficient ETR delivery throughout the SC and into the viable epidermis that correlated with clear anti-inflammatory effects. Notably, effective ETR delivery depended on temperature triggered release following topical application. Conclusion: Together these results indicate tNGs hold promise as a biocompatible and easy to manufacture vehicle for stable protein encapsulation and topical delivery into barrier-deficient skin.
This publication demonstrates the abilities of a precise and straightforward microcontact printing approach for the preparation of patchy silica particles. In a broad particle size range, it is possible to finely tune the number and parameters of three-dimensional patches like diameter and thickness using only polyethyleneimine ink, poly(dimethoxysilane) as stamp material and a suitable release solvent.
The problem of atmospheric emission from OH molecules is a long standing problem for near-infrared astronomy. PRAXIS is a unique spectrograph which is fed by fibres that remove the OH background and is optimised specifically to benefit from OH-Suppression. The OH suppression is achieved with fibre Bragg gratings, which were tested successfully on the GNOSIS instrument. PRAXIS uses the same fibre Bragg gratings as GNOSIS in its first implementation, and will exploit new, cheaper and more efficient, multicore fibre Bragg gratings in the second implementation. The OH lines are suppressed by a factor of similar to 1000, and the expected increase in the signal-to-noise in the interline regions compared to GNOSIS is a factor of similar to 9 with the GNOSIS gratings and a factor of similar to 17 with the new gratings. PRAXIS will enable the full exploitation of OH suppression for the first time, which was not achieved by GNOSIS (a retrofit to an existing instrument that was not OH-Suppression optimised) due to high thermal emission, low spectrograph transmission and detector noise. PRAXIS has extremely low thermal emission, through the cooling of all significantly emitting parts, including the fore-optics, the fibre Bragg gratings, a long length of fibre, and the fibre slit, and an optical design that minimises leaks of thermal emission from outside the spectrograph. PRAXIS has low detector noise through the use of a Hawaii-2RG detector, and a high throughput through a efficient VPH based spectrograph. PRAXIS will determine the absolute level of the interline continuum and enable observations of individual objects via an IFU. In this paper we give a status update and report on acceptance tests.
In order to replace bio-macromolecules by stable synthetic materials in separation techniques and bioanalysis biomimetic receptors and catalysts have been developed: Functional monomers are polymerized together with the target analyte and after template removal cavities are formed in the "molecularly imprinted polymer" (MIP) which resemble the active sites of antibodies and enzymes. Starting almost 80 years ago, around 1,100 papers on MIPs were published in 2016. Electropolymerization allows to deposit MIPs directly on voltammetric electrodes or chips for quartz crystal microbalance (QCM) and surface plasmon resonance (SPR). For the readout of MIPs for drugs amperometry, differential pulse voltammetry (DPV) and impedance spectroscopy (EIS) offer higher sensitivity as compared with QCM or SPR. Application of simple electrochemical devices allows both the reproducible preparation of MIP sensors, but also the sensitive signal generation. Electrochemical MIP-sensors for the whole arsenal of drugs, e.g. the most frequently used analgesics, antibiotics and anticancer drugs have been presented in literature and tested under laboratory conditions. These biomimetic sensors typically have measuring ranges covering the lower nano-up to millimolar concentration range and they are stable under extreme pH and in organic solvents like nonaqueous extracts.
The incorporation of inorganic particles in a polymer matrix has been established as a method to adjust the mechanical performance of composite materials. We report on the influence of covalent integration of magnetic nanoparticles (MNP) on the actuation behavior and mechanical performance of hybrid nanocomposite (H-NC) based shape-memory polymer actuators (SMPA). The H-NC were synthesized by reacting two types of oligo(ω-pentadecalactone) (OPDL) based precursors with terminal hydroxy groups, a three arm OPDL (3 AOPDL, Mn = 6000 g mol•1−1 ) and an OPDL (Mn =3300 g • mol−1 ) coated magnetite nanoparticle (Ø = 10 ± 2 nm), with a diisocyanate. These H-NC were compared to the homopolymer network regarding the actuation performance, contractual stress (σcontr) as well as thermal and mechanical properties. The melting range of the OPDL crystals (ΔTm,OPDL) was shifted in homo polymer networks from 36 ºC − 76 ºC to 41ºC − 81 °C for H-NC with 9 wt% of MNP content. The actuators were explored by variation of separating temperature (Tsep), which splits the OPDL crystalline domain into actuating and geometry determining segments. Tsep was varied in the melting range of the nanocomposites and the actuation capability and contractual stress (σcontr) of the nanocomposite actuators could be adjusted. The reversible strain (εrev) was decreased from 11 ± 0.3% for homo polymer network to 3.2±0.3% for H-NC9 with 9 wt% of MNP indicating a restraining effect of the MNP on chain mobility. The results show that the performance of H-NCs in terms of thermal and elastic properties can be tailored by MNP content, however for higher reversible actuation, lower MNP contents are preferable.
The synthesis, structure, and photocatalytic water splitting performance of two new titania (TiO2)/gold(Au)/Bombyx mori silk hybrid materials are reported. All materials are monoliths with diameters of up to ca. 4.5 cm. The materials are macroscopically homogeneous and porous with surface areas between 170 and 210 m(2)/g. The diameter of the TiO2 nanoparticles (NPs) - mainly anatase with a minor fraction of brookite - and the Au NPs are on the order of 5 and 7-18 nm, respectively. Addition of poly(ethylene oxide) to the reaction mixture enables pore size tuning, thus providing access to different materials with different photocatalytic activities. Water splitting experiments using a sunlight simulator and a Xe lamp show that the new hybrid materials are effective water splitting catalysts and produce up to 30 mmol of hydrogen per 24 h. Overall the article demonstrates that the combination of a renewable and robust scaffold such as B. mori silk with a photoactive material provides a promising approach to new monolithic photocatalysts that can easily be recycled and show great potential for application in lightweight devices for green fuel production.
The reaction between propargyl ethers of hydroxybenzaldehydes and the ylide ethyl (triphenylphosphoranylidene)acetate was carried out under microwave irradiation to regioselectively afford angular pyranocoumarins. The chromene and coumarin heterocyclic scaffolds were simultaneously formed in the same synthetic step without changing the reaction conditions. The natural products seselin, braylin, and dipetalolactone were among the products synthesized by this method.