Development of a surface to increase retinal pigment epithelial cell (ARPE-19) proliferation under reduced serum conditions.

Age related macular degeneration of the eye is brought about by damage to the retinal pigment epithelium (RPE) and is a major cause of adult blindness. One potential treatment method is transplantation of RPE cells grown in vitro. Maintaining RPE cell viability and physiological function in vitro is a challenge, and this must also be achieved using materials that can be subsequently used to deliver an intact cell sheet into the eye. In this paper, plasma polymerisation has been used to develop a chemically modified surface for maintaining RPE cells in vitro. Multiwell plates modified with a plasma copolymer of allylamine and octadiene maintained RPE cell growth at a level similar to that of TCPS. However, the addition of bound glycosaminoglycans (GAGs) to the plasma polymerised surface significantly enhanced RPE proliferation. Simply adding GAG to the culture media had no positive effect. It is shown that a combination of plasma polymer and GAG is a promising method for developing suitable surfaces for cell growth and delivery, that can be applied to any substrate material.

Role of positive ions in determining the deposition rate and film chemistry of continuous wave hexamethyl disiloxane plasmas.

New data shed light on the mechanisms of film growth from low power, low pressure plasmas of organic compounds. These data rebalance the widely held view that plasma polymer formation is due to radical/neutral reactions only and that ions play no direct role in contributing mass at the surface. Ion reactions are shown to play an important role in both the plasma phase and at the surface. The mass deposition rate and ion flux in continuous wave hexamethyl disiloxane (HMDSO) plasmas have been studied as a function of pressure and applied RF power. Both the deposition rate and ion flux were shown to increase with applied power; however, the deposition rate increased with pressure while the ion flux decreased. Positive ion mass spectrometry of the plasma phase demonstrates that the dominant ionic species is the (HMDSO-CH(3))(+) ion at m/z 147, but significant fragmentation and subsequent oligomerization was also observed. Chemical analysis of the deposits by X-ray photoelectron spectroscopy and secondary ion mass spectrometry show that the deposits were consistent with deposits reported by previous workers grown from plasma and hyperthermal (HMDSO-CH(3))(+) ions. Increasing coordination of silicon with oxygen in the plasma deposits reveals the role of ions in the growth of plasma polymers. Comparing the calculated film thicknesses after a fixed total fluence of 1.5 × 10(19) ions/m(2) to results for hyperthermal ions shows that ions can contribute significantly to the total absorbed mass in the deposits.

Utilization of Point-of-Care Ultrasonography (POCUS) for Small Bowel Obstruction.

Small bowel obstruction is a frequently encountered condition throughout emergency departments and accounts for a large number of surgical hospital admissions. Point-of-care ultrasonography (POCUS) by emergency providers can serve as a valuable tool to assist in prompt and accurate diagnosis, which could potentially reduce the quantity of undesirable effects such as radiation and cost seen with other advanced imaging modalities (e.g., computed tomography).

Development of a surface to enhance the effectiveness of fibroblast growth factor 2 (FGF-2).

Growth factors (GFs) play an important role in biological processes such as cell proliferation, differentiation and angiogenesis. GFs are known to bind to glycosaminoglycans (GAGs) in the extracellular matrix, aiding projection from degradation and pooling the GFs for quick response to biological stimuli in vivo. GFs are typically expensive and have a relatively short half-life in culture media, requiring regular replenishment. Here the cooperative binding of GF to a plasma polymerised surface decorated with heparin, and the subsequent culture of primary human dermal fibroblasts (HDFs) is investigated. A simple one-step technique suitable for coating a wide range of different substrates was utilised. Substrates such as culture-ware, scaffolds, bandages and devices for implantation could be coated. The modified surface was compared to standard culture techniques of addition of GF to the media. Results demonstrate that surface bound heparin and FGF-2 have a greater effect on cell proliferation especially at reduced serum concentrations. With performance equivalent to supplementing the media achieved at as little as 1% total FGF-2 added. The protective cooperative effect of FGF-2-GAG bound to modified surface at the interface could lead to reduced costs by reduction of FGF-2 required. Furthermore, for applications such as chronic non-healing wounds, bandages can be produced modified by plasma and decorated with GAGs that could utilise and protect important GFs. This would effectively re-introduce important biomolecules which are protected by GAG binding into a harsh environment.

Glycosaminoglycan (GAG) binding surfaces for characterizing GAG-protein interactions.

Glycosaminoglycans play an important role in tissue organisation through interactions with a diverse range of proteins, growth factors and other chemokines. In this report, we demonstrate the GAG-binding 'fingerprint' of two important GAG-binding proteins - osteoprotogerin and TIMP-3. The technique uses a straightforward method for attaching GAGs to assay surfaces in a non-covalent manner using plasma polymerization that leaves the adsorbed GAG able to participate in subsequent ligand binding. We show that OPG and TIMP-3 bind preferentially to different GAGs in a simple ELISA and that this binding does not correlate directly with simple GAG properties such as degree of sulfation. The methods outlined in this report can be easily applied to tissue engineering scaffolds in order to exploit the potential of surface-bound GAGs in influencing the structure of engineered tissues.

Microplasma patterning of bonded microchannels using high-precision "injected" electrodes.

A rapid, high-precision method for localised plasma-treatment of bonded PDMS microchannels is demonstrated. Patterned electrodes were prepared by injection of molten gallium into preformed microchannel guides. The electrode guides were prepared without any additional fabrication steps compared to conventional microchannel fabrication. Alignment of the "injected" electrodes is precisely controlled by the photomask design, rather than positioning accuracy of alignment tools. Surface modification is detected using a fluorescent dye (Rhodamine B), revealing a well-defined micropattern with regions less than 100 µm along the length of the microchannel.

Osteoblast biocompatibility on poly(octanediol citrate)/sebacate elastomers with controlled wettability.

This work examines the biocompatibility of poly(octanediol citrate)/sebacate (p(OCS)) biodegradable polyester elastomers. The growth of human MG63 osteoblast-like cells was studied on p(OCS) films. Three types of p(OCS) films were synthesised simply by varying the concentrations of 1,8-octanediol (OD), citric acid (CA), and sebacic acid (SA) monomers at initial molar ratios of 1:1:0, 1:0.75:0.25 and 1:0.5:0.5. At these ratios, the p(OCS) films exhibit decreasing hydrophilicity as shown by the measured water contact angle values of 31, 41 and 64 degrees , respectively. For all the samples, no difference in cell growth was detected after 1 day of cell culture. However, after 4 days, the highest number of viable cells was detected on the p(OCS) film synthesised with the intermediate CA molar ratio of 0.75. This sample also contains the median concentration of surface carboxylic acid groups and hydrophilicity. Following long-term cell culture (18 days), a statistically significant higher density of viable cells had grown on the p(OCS) films with SA molar ratios of 0.25 (P < 0.0001) and 0.5 (P = 0.002) in comparison to the material containing 100% CA and no SA. The work demonstrated that the performance of possible p(OCS) bone tissue engineering scaffolds could be improved by simply adjusting the molar ratios of CA and SA in the pre-polymer without any requirements for post-synthesis modification.

Polyoctanediol citrate/sebacate bioelastomer films: surface morphology, chemistry and functionality.

Elastomeric polyesters synthesized from non-toxic and biocompatible reactants are topical research materials for tissue-engineering applications. In such applications, the morphology, chemistry and functionality of the materials surfaces play a key role. While a number of papers have focused and reported on the fabrication and biological evaluation of elastic polyesters, only a few have attempted to characterise the surfaces of such materials. In this paper, we report on the preparation and surface characterization of films of a co-polyester bioelastomer, polyoctanediol citrate/sebacate (p(OCS)). The co-polymer was synthesized following the standard procedure of polyesterification using three non-toxic monomers (1,8-octanediol, citric acid and sebacic acid) in a catalyst-free environment. Nuclear magnetic resonance spectroscopy was used to monitor the chemical composition of the various p(OCS) elastomers. The p(OCS) films, prepared by both spin-coating and solvent casting of the p(OCS) pre-polymer solutions, were characterized by scanning electron microscopy, UV-Vis titration, photo-acoustic Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, and tested for their cytocompatibility. The results obtained suggest that the surface morphology, chemistry and the concentration of the surface functional groups can be controlled by simply varying the initial acid concentration (citric/sebacic acids) in the pre-polymer. The films supported the attachment and proliferation of osteoblast-like cells (MG63). This unique approach provides an effective method of controlling and monitoring the fundamental p(OCS) surface properties important for their potential utilisation as a tissue-engineering material.

Submillimeter-scale surface gradients of immobilized protein ligands.

We describe a method to produce antibody-captured ligand gradients over biologically relevant distances (hundreds of micrometers) whereby the ligand density and gradient shape may be tailored. Separation of the ligand from the solid-phase surface ensures that the biological activity of the ligand remains unaffected by immobilization. Our method involves the use of a plasma-masking method to generate a surface chemical gradient on a glass substrate to which the 9E10 antibody is covalently coupled. This antibody captures myc-tagged biomolecules. In our example, the antibody is then used to immobilize a gradient of the intercellular signaling molecule delta-like-1 (Dll1). To visualize the gradient of Dll1, we have used the multistep approach of binding with rabbit anti-Dll1 primary antibody and then adding colloidal-gold-conjugated secondary antibody.

The geometric control of E14 and R1 mouse embryonic stem cell pluripotency by plasma polymer surface chemical gradients.

Plasma polymer surfaces were fabricated such that the cell response to a range of carboxylic acid concentrations on a single sample could be investigated. Surface chemical gradients from hydrophobic plasma polymerised octadiene (OD) to a more hydrophilic plasma polymerised acrylic acid (AA) were formed on glass coverslips. Surface characterisation of the chemical gradients was performed using X-ray photoelectron spectroscopy to determine elemental composition. Following culture of E14 and R1 mouse embryonic stem cells (mES) in differing culture media, cell pluripotency was determined by alkaline phosphatase staining. The results demonstrate that for these cell lines the capacity for self-renewal is maintained if the cells are restricted in their spreading to <120 microm2.

Preoperative chemoembolization for unresectable hepatoblastoma.

Complete surgical resection offers the only chance for cure in patients with hepatoblastoma (HB). Patients with unresectable lesions are given preoperative chemotherapy in an attempt to create a resectable lesion. We present a case of an 11-month-old with an unresectable stage III HB unresponsive to systemic chemotherapy. Transfemoral hepatic-artery chemoembolization resulted in a surgically resectable tumor. The patient underwent a right trisegmentectomy with complete resection of the tumor and remains tumor-free 24 months postoperatively. Salvage chemoembolization can be an effective preoperative modality to convert an unresectable tumor into a resectable one.