20 research outputs found
Buttressing staples with cholecyst-derived extracellular matrix (CEM) reinforces staple lines in an ex vivo peristaltic inflation model
No full textThis is the author's accepted manuscript. The final published article is available from the link below. Copyright @ Springer Science + Business Media, LLC 2008Background - Staple line leakage and bleeding are the most common problems associated with the use of surgical staplers for gastrointestinal resection and anastomotic procedures. These complications can be reduced by reinforcing the staple lines with buttressing materials. The current study reports the potential use of cholecyst-derived extracellular matrix (CEM) in non-crosslinked (NCEM) and crosslinked (XCEM) forms, and compares their mechanical performance with clinically available buttress materials [small intestinal submucosa (SIS) and bovine pericardium (BP)] in an ex vivo small intestine model.
Methods - Three crosslinked CEM variants (XCEM0005, XCEM001, and XCEM0033) with different degree of crosslinking were produced. An ex vivo peristaltic inflation model was established. Porcine small intestine segments were stapled on one end, using buttressed or non-buttressed surgical staplers. The opened, non-stapled ends were connected to a peristaltic pump and pressure transducer and sealed. The staple lines were then exposed to increased intraluminal pressure in a peristaltic manner. Both the leak and burst pressures of the test specimens were recorded.
Results - The leak pressures observed for non-crosslinked NCEM (137.8 ± 22.3 mmHg), crosslinked XCEM0005 (109.1 ± 14.1 mmHg), XCEM001 (150.1 ± 16.0 mmHg), XCEM0033 (98.8 ± 10.5 mmHg) reinforced staple lines were significantly higher when compared to non-buttressed control (28.3 ± 10.8 mmHg) and SIS (one and four layers) (62.6 ± 11.8 and 57.6 ± 12.3 mmHg, respectively) buttressed staple lines. NCEM and XCEM were comparable to that observed for BP buttressed staple lines (138.8 ± 3.6 mmHg). Only specimens with reinforced staple lines were able to achieve high intraluminal pressures (ruptured at the intestinal mesentery), indicating that buttress reinforcements were able to withstand pressure higher than that of natural tissue (physiological failure).
Conclusions - These findings suggest that the use of CEM and XCEM as buttressing materials is associated with reinforced staple lines and increased leak pressures when compared to non-buttressed staple lines. CEM and XCEM were found to perform comparably with clinically available buttress materials in this ex vivo model.Enterprise Irelan
Nanomaterials in glucose sensing
No full textResearch shows that overall, nanomaterials help address the problems with conventional optical and electrochemical biosensors, by enhancing the preferential detection of glucose or its oxidation products through better electron transfer kinetics, sensitivity and response time, while lowering the operating over-voltages for energy efficiency and avoid interference. The reproducible production of nano-materials and nano-structures at low cost is vital for the successful development of nano-technologies for glucose sensing. Several products, especially, home glucose monitoring devices, use nano-materials, but the need for reliable long-term CGM is still unmet. Nano-materials and nano-technologies have an important role in achieving the long-awaited CGM technology
Chapter 11. Electrospinning for Medical Applications
No full textThere is a natural connection between a variety of electrospun fibres and biomedical applications. The most commonly quoted application of electrospun fibres is their use as scaffolds in tissue engineering for regenerative medicine. There are also many other applications, which include drug delivery systems, membrane systems and analytical functionality. This chapter identifies the key challenges in each of these topics, as well as the particular role of electrospun fibres in addressing these challenges
Biomimetic Electrospun Coatings Increase the In Vivo Sensitivity of Implantable Glucose Biosensors
No full textIn vivo tissue responses and functional efficacy of electrospun membranes based on polyurethane (PU) and gelatin (GE) as biomimetic coatings for implantable glucose biosensors was investigated in a rat subcutaneous implantation model. Three electrospun membranes with optimized fiber diameters, pore sizes, and permeability, both single PU and coaxial PU-GE fibers and a solvent cast PU film were implanted in rats to evaluate tissue responses. For functional efficacy testing, four sensor variants coated with the above mentioned electrospun membranes as mass-transport limiting and outermost biomimetic coatings were implanted in rats. The electrospun PU membranes had micron sized pores that were not permeable to host cells when implanted in the body. However, PU-GE coaxial fiber membranes, having similar sized pores, were infiltrated with fibroblasts that deposited collagen in the membrane's pores. Such tissue response prevented the formation of dense fibrous capsule around the sensor coated with the PU-GE coaxial fiber membranes, which helped improve the in vivo sensitivity for at least 3 weeks compared to the traditional sensors in rat subcutaneous tissue. Furthermore, the better in vitro sensor's sensitivity due to electrospun PU as the mass-transport limiting membrane translated to better in vivo sensitivity. Thus, this study showed that electrospun membranes can play an important role in realizing long in vivo sensing lifetime of implantable glucose biosensors
A clinically relevant in vivo model for the assessment of scaffold efficacy in abdominal wall reconstruction
No full textCopyright © The Author(s) 2017. An animal model that allows for assessment of the degree of stretching or contraction of the implant area and the in vivo degradation properties of biological meshes is required to evaluate their performance in vivo. Adult New Zealand rabbits underwent full thickness subtotal unilateral rectus abdominis muscle excision and were reconstructed with the non-biodegradable Peri-Guard®, Prolene® or biodegradable Surgisis® meshes. Following 8 weeks of recovery, the anterior abdominal wall tissue samples were collected for measurement of the implant dimensions. The Peri-Guard and Prolene meshes showed a slight and obvious shrinkage, respectively, whereas the Surgisis mesh showed stretching, resulting in hernia formation. Surgisis meshes showed in vivo biodegradation and increased collagen formation. This surgical rabbit model for abdominal wall defects is advantageous for evaluating the in vivo behaviour of surgical meshes. Implant area stretching and shrinkage were detected corresponding to mesh properties, and histological analysis and stereological methods supported these findings.This study was financially supported by the Enterprise Ireland (Technology Development Grant). This publication has emanated from research conducted with the financial support of Science Foundation Ireland (SFI) and is co-funded under the European Regional Development Fund under grant no. 13/RC/2073. This study was also supported by the Centre for Microscopy & Imaging funded by NUI Galway and PRTLI, Cycles 4 and 5, National Development Plan 2007–2013
Interpenetrating polymer networks based on poly(acrylic acid) and gelatin. I: Swelling and thermal behavior
No full text
Hydrogel Membrane Improves Batch-to-Batch Reproducibility of an Enzymatic Glucose Biosensor
No full textA permselective membrane is a critical component that defines the linear detection limits, the sensitivity, and thus the ultimate efficacy of an enzymatic biosensor. Although membranes like epoxy-polyurethane (epoxy-PU) and Nafion are widely used and provide the desired glucose detection limits of 2 to 30 mM, both the within batch and batch-to-batch variability of sensors that use these materials is a concern. The hypothesis for this study was that a crosslinked hydrogel would have a sufficiently uniform porosity and hydrophilicity to address the variability in sensor sensitivity. The hydrogel was prepared by crosslinking di-hydroxyethyl methacrylate, hydroxyethyl methacrylate and N-vinyl pyrrolidone with 2.5 mol% ethylene glycol dimethacrylate using water soluble initiators – ammonium persulfate and sodium metabisulfite under a nitrogen atmosphere. The hydrogel was applied to the sensor by dip coating during polymerisation. Electrochemical measurements revealed that the response characteristics of sensors coated with this membrane are highly consistent. Scanning electrochemical microscopy (SECM) was used to spatially resolve glucose diffusion through the membrane by measuring the consequent H2O2 release and compared with an epoxy-PU membrane. Hydrogen peroxide measurements using SECM revealed that the epoxy-PU membranes had uneven lateral diffusion profiles compared to the uniform profile of the hydrogel membranes. The uneven diffusion profiles of epoxy-PU membranes are attributed to a fabrication method that results in uneven membrane properties, while the uniform diffusion profiles of the hydrogel membranes are primarily dictated by their uniform pore size
Efficacy of crosslinking on tailoring in vivo biodegradability of fibro-porous decellularized extracellular matrix and restoration of native tissue structure: A quantitative study using stereology methods
No full textCholecyst-derived extracellular matrix (CEM) is a fibro-porous decellularized serosal layer of porcine gall-bladder. CEM loses 90% of its weight at 48 h of in vitro collagenase digestion, but takes two months to be completely resorbed in vivo. Carbodiimide (EDC) crosslinking helps tailoring CEM's in vitro collagenase susceptibility. Here, the efficacy of EDC crosslinking on tailoring in vivo biodegradability of CEM is reported. CEM crosslinked with 0.0005 and 0.0033 × 103 M of EDC/mg that lose 80% and 0% of their weight respectively to in vitro collagenase digestion, were present even after 180 days in vivo. Quantitative histopathology using stereology methods confirmed our qualitative observation that even a tiny degree of crosslinking can significantly prolong the rate of in vivo degradation and removal of CEM. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Enterprise Ireland – Technology Developmen
