Direct Imaging of Mechanical and Chemical Gradients Across the Thickness of Graded Organosilicone Microwave PECVD Coatings

The characterization of variations in the chemical composition and ensuing mechanical properties across the thickness of coatings with continuously varying compositions through their thickness (graded coatings) presents considerable challenges for current analytical techniques in materials science. We report here the direct imaging of nanomechanical and chemical gradients across cross-sections of an organosilicone coating fabricated via microwave plasma enhanced chemical vapor deposition (PECVD). Cross-sectional nanoindentation was used to determine the mechanical properties of uniform and graded organosilicone coatings. Both hardness and modulus across the coatings were directly measured. Additionally, “modulus mapping” on cross-sections was used to map the complex modulus. For the graded coating, it was found that variations in the complex modulus was predominantly due to varying storage modulus. It was observed that at the interface with the substrate there was a low storage modulus, which linearly increased to a relatively high storage modulus at the surface. It is proposed that the increase in stiffness, from the substrate interface to the outer surface, is due to the increasing content of a cross-linked O–Si–O network. This mechanical gradient has been linked to a change in the Si:O ratio via direct compositional mapping using ToF-SIMS. Direct mapping of the mechanical and compositional gradients across these protective coatings provides insight into the changes in properties with depth and supports optimization of the critical mechanical performance of PECVD graded coatings

Important factors in the design of anti-infective materials and their surface coatings.

<p>Important factors in the design of anti-infective materials and their surface coatings.</p

Cellular Micromotion Monitored by Long-Range Surface Plasmon Resonance with Optical Fluctuation Analysis

Long-range surface plasmon resonance (LRSPR) is a powerful biosensing technology due to a substantially larger probing depth into the medium and sensitivity, compared with conventional SPR. We demonstrate here that LRSPR can provide sensitive noninvasive measurement of the dynamic fluctuation of adherent cells, often referred to as the cellular micromotion. Proof of concept was achieved using confluent layers of 3T3 fibroblast cells and MDA-MB-231 cancer cells. The slope of the power spectral density (PSD) of the optical fluctuations was calculated to determine the micromotion index, and significant differences were measured between live and fixed cell layers. Furthermore, the performances of LRSPR and conventional surface plasmon resonance (cSPR) were compared with respect to micromotion monitoring. Our study showed that the micromotion index of cells measured by LRSPR sensors was higher than when measured with cSPR, suggesting a higher sensitivity of LRSPR to the micromotion of cells. To investigate further this finding, simulations were conducted to establish the relative sensitivities of LRSPR and cSPR to membrane fluctuations. Increased signal intensity was predicted for LRSPR in comparison to cSPR, suggesting that membrane fluctuations play a significant role in the optical micromotion measured in LRSPR. Analogous to cellular micromotion measured using impedance techniques, LRSPR micromotion has the potential to provide important biological information on the metabolic activity and viability of adherent cells

Affinity Binding of EMR2 Expressing Cells by Surface-Grafted Chondroitin Sulfate B

The propensity of glycosaminoglycans to mediate cell–cell and cell–matrix interactions opens the door to capture cells, including circulating blood cells, onto biomaterial substrates. Chondroitin sulfate (CS)-B is of particular interest, since it interacts with the receptor (EGF)-like module-containing mucin-like hormone receptor-like 2 precursor (EMR2) displayed on the surface of leukocytes and endothelial progenitor cells. Herein, CS-B and its isomer CS-A were covalently immobilized onto heptylamine plasma polymer films via three different binding chemistries to develop platform technology for the capture of EMR2 expressing cells onto solid carriers. Surface characterization verified the successful immobilization of both glycosaminoglycans. The EMR2 expressing human myeloid cell line U937 preferentially bound onto CS-B-modified substrates, and U937 cells preincubated with CS-B in solution exhibited reduced affinity for the substrate. The direct capture of hematopoietic and blood-circulating endothelial cell types via a glycosaminoglycan-binding surface receptor opens an unexplored route for the development of biomaterials targeted at these cell types

Parvifloranines A and B, Two 11-Carbon Alkaloids from <i>Geijera parviflora</i>

Two novel alkaloids (parvifloranines A and B), possessing an unusual 11-carbon skeleton linked with amino acids, were isolated from <i>Geijera parviflora</i>, an endemic Australian Rutaceae. Their structures were elucidated by extensive spectroscopic measurements including 2D NMR analyses. Parvifloranine A was found to be a mixture of two enantiomers, (<i>S</i>)-<b>1</b> and (<i>R</i>)-<b>1</b>, in a ratio of 1:4, based on their separation using a chiral column. Parvifloranine B is also believed to be a mixture of enantiomers. Proposed biosynthetic pathways are discussed. Parvifloranine A inhibited the synthesis of nitric oxide in LPS-stimulated RAW 264.7 macrophages with an IC₅₀ value of 23.4 μM

Characterisation of plasma modified surface and GFP-mMSCs expansion in our packed bed bioreactor in static and perfusion conditions.

<p>(A) Surface composition of the air plasma treated polystyrene scaffold determined by XPS. (B) GFP-mMSC attachment after one and half hours, initially seeded at 3000 cells/cm² (n = 4). (C) The growth after 3 days of culture of GFP-mMSC seeded at 1000 cells/cm² (n = 6). (D) Growth of GFP-mMSC in the bioreactor (BR) under static conditions (n = 4) and (E) under 5 mL/day perfusion (n = 4). (F) Cell harvest recovery and viablity from the bioreactor. (G, H, I and J) Fluorescent microscopy showed that the GFP-mMSC attached to the scaffold (scale bar is 500 μm). (K) IVIS imaging of the fluorescent intensity of PI stained GFP-mMSC in the bioreactor under static and (L) 5 mL/day perfusion conditions. IVIS images are a red (low) / yellow (high) heat map of fluorescent intensity.</p

Pre-isolated passage four pMSC expanded in our bioreactor in static and perfusion conditions.

<p>(A) pMSC expansion in the small-scale 160 cm² bioreactor (BR) in static (n = 4) and (B) 5 mL/day perfusion (n = 4), with the 2D controls (2D). (C) IVIS imaging of PI stained pMSC under perfusion conditions. IVIS images are a red (low) / yellow (high) heat map of fluorescent intensity. (D) Two week tri-lineage mesodermal differentiation induction of bioreactor expanded pMSC and 2D controls down the adipogenic (Oil Red O, 10x, scale bar is 100 μm), osteogenic (Alizarin Red, 5x, scale bar 500 μm) and chondrogenic (Alcian Blue, 10x, scale bar 500 μm) lineages. Quantification of (E) triglycerides (n = 4), (F) ALP activity (n = 4) and (G) GAG production.</p

Biologically Active Dibenzofurans from <i>Pilidiostigma glabrum</i>, an Endemic Australian Myrtaceae

In an effort to identify new anti-inflammatory and antibacterial agents with potential application in wound healing, five new dibenzofurans, 1,3,7,9-tetrahydroxy-2,8-dimethyl-4,6-di­(2-methylbutanoyl)­dibenzofuran (<b>1</b>), 1,3,7,9-tetrahydroxy-2,8-dimethyl-4-(2-methylbutanoyl)-6-(2-methylpropionyl)­dibenzofuran (<b>2</b>), 1,3,7,9-tetrahydroxy-2,8-dimethyl-4,6-di­(2-methylpropionyl)­dibenzofuran (<b>3</b>), 1,3,7,9-tetrahydroxy-4,6-dimethyl-2-(2-methylbutanoyl)-8-(2-methylpropionyl)­dibenzofuran (<b>4</b>), and 1,3,7,9-tetrahydroxy-4,6-dimethyl-2,8-di­(2-methylpropionyl)­dibenzofuran (<b>5</b>), were isolated from the leaves of <i>Pilidiostigma glabrum</i> together with one previously described dibenzofuran. Structure elucidation was achieved by way of spectroscopic measurements including 2D-NMR spectroscopy. Compounds with 2,8-acyl substitutions had potent antibacterial activity against several Gram-positive strains (MIC in the low micromolar range), while compounds with 4,6-acyl substitutions were less active. All compounds except <b>3</b> inhibited the synthesis of nitric oxide in RAW264 macrophages with IC₅₀ values in the low micromolar range. Compounds with 2,8-acyl substitutions also inhibited the synthesis of PGE₂ in 3T3 cells, whereas 4,6-acyl-substituted compounds were inactive. None of the compounds inhibited the synthesis of TNF-α in RAW264 cells. The compounds showed variable but modest antioxidant activity in the oxygen radical absorbance capacity assay. These findings highlight that much of the Australian flora remains unexplored and may yet yield many new compounds of interest. Initial clues are provided on structure/activity relationships for this class of bioactives, which may enable the design and synthesis of compounds with higher activity and/or selectivity

GFP-mMSC expansion in a scaled-up packed bed bioreactor (A) The fold expansion of GFP-mMSC in a scaled-up bioreactor under 0.5 ml/min perfusion with T175 flask control (n = 4). (B) Glucose and lactate levels in the bioreactor (n = 3). (C, D, E & F) IVIS imaging of the fluorescent intensity of PI stained GFP-mMSC in the bioreactor.

<p>IVIS images are a red (low) / yellow (high) heat map of fluorescent intensity.</p

Serrulatane Diterpenoid from <i>Eremophila neglecta</i> Exhibits Bacterial Biofilm Dispersion and Inhibits Release of Pro-inflammatory Cytokines from Activated Macrophages

The purpose of this study was to assess the biofilm-removing efficacy and inflammatory activity of a serrulatane diterpenoid, 8-hydroxyserrulat-14-en-19-oic acid (<b>1</b>), isolated from the Australian medicinal plant <i>Eremophila neglecta.</i> Biofilm breakup activity of compound <b>1</b> on established <i>Staphylococcus epidermidis</i> and <i>Staphylococcus aureus</i> biofilms was compared to the antiseptic chlorhexidine and antibiotic levofloxacin. In a time-course study, <b>1</b> was deposited onto polypropylene mesh to mimic a wound dressing and tested for biofilm removal. The <i>ex-vivo</i> cytotoxicity and effect on lipopolysaccharide-induced pro-inflammatory cytokine release were studied in mouse primary bone-marrow-derived macrophage (BMDM) cells. Compound <b>1</b> was effective in dispersing 12 h pre-established biofilms with a 7 log₁₀ reduction of viable bacterial cell counts, but was less active against 24 h biofilms (approximately 2 log₁₀ reduction). Compound-loaded mesh showed dosage-dependent biofilm-removing capability. In addition, compound <b>1</b> displayed a significant inhibitory effect on tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) secretion from BMDM cells, but interleukin-1 beta (IL-1β) secretion was not significant. The compound was not cytotoxic to BMDM cells at concentrations effective in removing biofilm and lowering cytokine release. These findings highlight the potential of this serrulatane diterpenoid to be further developed for applications in wound management