Low Concentrations Of Glutaraldehyde Research Articles

A thin biofilm of chitosan as a sorptive phase in the rotating disk sorptive extraction of triclosan and methyl triclosan from water samples

The features and nature of the sorptive phase may be the stage that determines the scope of microextraction techniques. In search of new alternatives, materials of natural origin have recently been explored to establish greener analytical strategies. Based on that search, this research proposes the use of chitosan as a sorptive phase, which was assessed in the rotating disk sorptive extraction of emerging contaminants from aqueous systems. Chitosan is a biopolymer of animal origin that is usually found in the shells of crustaceans. The main characteristic of this material is the presence of a high number of nitrogenous groups, which gives it high reactivity, but its main disadvantage is associated with its high swelling capacity.In this research, chitosan was crosslinked with a low concentration of glutaraldehyde to form thin films that were easily immobilized on the surface of the rotating disk. The main advantage of this modification is the considerable decrease in the swelling capacity, which prevents loss and rupture of the sorbent during high rotation of the disk. In addition, it not only improved the physical characteristics of chitosan but also increased its extraction capacity. With regard to its use as a sorptive phase, all the variables associated with the microextraction of the analytes were studied, and optimal variables were found to be: pH 4, 20% NaCl (salting out effect), 30–45 min as equilibrium time and elution of analytes with a mixture of methanol:ethyl acetate (1:1).Validation of the methodology for the determination of methyl triclosan and triclosan was carried out, and relative recoveries between 89 and 96% and relative standard deviations less than 14% were found. The detection limits were 0.11 and 0.20 μg L−1, respectively. Through its application in real samples (natural and residual waters), triclosan was quantified between 0.7 and 1.3 μg L−1. Finally, the “green” properties of the phase were evaluated, demonstrating that it is reusable for at least three cycles and biodegradable. Compared to its efficiency with a commercial phase (in this case, the styrene divinyl benzene phase), the proposed biosorbent provided a similar and even higher sorptive capacity (depending on the analyte).

The influence of glutaraldehyde on the microscopic structure of human pericardium

ObjectivesIn our study, we investigate the collagen structure of human pericardium microscopically in dependence of glutaraldehyde (GA) concentration and fixation time. MethodsPericardial samples were taken from 9 patients aged 40+ years who underwent cardiac surgery, either coronary artery bypass surgery or valve implantation/reconstruction. Specimens were cut in 5 equal pieces and treated with GA at fixed concentrations (0.3125%, 0.625%, or 1.25%) but different exposer times (5 min, 10 min, 20 min, 30 min, and 60 min). Elastica van Gieson (EvG) staining was used for microscopic examination of pericardial collagen structure. ResultsThe collagen structure studied microscopically depended on both GA incubation time and GA concentration. At low GA concentrations (0.3125%, 0.625%) and short incubation times, individual collagen fibers appeared separately. After one hour incubation period, single collagen fibers could not be distinguished at any GA concentration. For fixed incubation times no differences were seen in the collagen structure when 0.3125% and 0.625% GA were used. However, at a concentration of 1.25% GA fusion of individual collagen fibers was already observed at low incubation times. ConclusionPericardial collagen structure changes with increasing incubation time and increasing GA concentration by raising fusion of single fibers. For GA concentrations of ≤0.625%, fiber fusion depends plainly on incubation time. That is relevant as this concentration is used in cardiac surgery. At a concentration of 1.25% GA, single collagen fibers could not be separated, even at short incubation times. Fusion of individual collagen fibers and changes in appearance (less undulating) were assumed to be responsible for stiffening of GA-fixed pericardium.

Virucidal effect of commercial disinfectants on fowl adenovirus serotype 1 strains causing chicken gizzard erosion in Japan

Summary To find an efficient control method for gizzard erosion (GE) caused by fowl adenovirus serotype 1 (FAdV-1) infection in poultry farms, we examined the virucidal effects of commercial disinfectants. In laboratory tests, the virucidal effects of the disinfectants calcium hydroxide (CHO), glutaraldehyde (GLT), orthodichlorobenzene, cresol, and didecyldimethylammonium chloride against FAdV-1s were examined. Among them, CHO and GLT were extremely effective in all tested viruses, even at low concentrations, under the condition of 20°C. However, virucidal effect under the condition of 4°C at low concentrations of GLT was attenuated. Then, in a broiler farm where GE in chickens continuously occurred, we applied 2 combinations of disinfectants on the inside and outside of poultry houses every “chicken-free” period after shipping of chickens. The disinfection effect was then evaluated by gizzard rejection rate in the next flock. We detected GE in the flocks after disinfection with a combination of GLT and CHO at an ambient temperature of approximately 11°C. Moreover, we detected GE in the flock after disinfecting with didecyldimethylammonium chloride and CHO, regardless of the environmental temperature. In contrast, we did not detect GE in the flock after disinfecting with GLT and CHO under the condition of ambient temperature of approximately 21°C. These findings underline the importance of performing thorough disinfection with effective disinfectants during the “chicken-free” downtime to prevent the persistence of GE caused by FAdV-1 infection. It is necessary to use liquid disinfectants such as GLT and to pay close attention to ambient temperatures and the working concentration of disinfectants.

Effect of microtubule immobilization by glutaraldehyde on kinesin-driven cargo transport

The glutaraldehyde fixation method for fixing tissues is attractive for its ease of use and straightforward surface chemistry. We investigated the effect of glutaraldehyde-induced microtubule immobilization on kinesin-driven cargo transport along microtubules and found that at low glutaraldehyde concentrations, the microtubule–kinesin interaction remains unperturbed. Such findings may facilitate the application of the glutaraldehyde fixation method for many in vitro studies aiming to build nanodevices powered by the microtubule–motor protein interaction. The graphical abstract shows that the kinesin-driven quantum dot transport along microtubule immobilized on a substrate using glutaraldehyde concentration ≤0.10% (v/v) remain unaltered, whereas, at higher glutaraldehyde concentration, >0.10% (v/v), the quantum dot transportation is slowed down.

Immunocytochemical Analysis of α-Tubulin Distribution Before and After Rapid Axopodial Contraction in the Centrohelid Raphidocystis contractilis

The centrohelid Raphidocystis contractilis is a heliozoan that has many radiating axopodia, each containing a bundle of microtubules. Although the rapid contraction of the axopodia at nearly a video rate (30 frames/s) is induced by mechanical stimuli, the mechanism underlying this phenomenon in R. contractilis has not yet been elucidated. In the present study, we described for the first time an adequate immunocytochemical fixation procedure for R. contractilis and the cellular distribution of α-tubulin before and after rapid axopodial contraction. We developed a flow-through chamber equipped with a micro-syringe pump that allowed the test solution to be injected at a flow rate below the threshold required to induce rapid axopodial contraction. Next, we used this injection method for evaluating the effects of different combinations of two fixatives (paraformaldehyde or glutaraldehyde) and two buffers (phosphate buffer or PHEM) on the morphological structure of the axopodia. A low concentration of glutaraldehyde in PHEM was identified as an adequate fixative for immunocytochemistry. The distribution of α-tubulin before and after rapid axopodial contraction was examined using immunocytochemistry and confocal laser scanning fluorescence microscopy. Positive signals were initially detected along the extended axopodia from the tips to the bases and were distributed in a non-uniform manner within the axopodia. Conversely, after the induction of a rapid axopodial contraction, these positive signals accumulated in the peripheral region of the cell. These results indicated that axopodial microtubules disassemble into fragments and/ or tubulin subunits during rapid axopodial contraction. Therefore, we hypothesize that the mechanism of extremely rapid axopodial contraction accompanied by cytoskeletal microtubule degradati

Glutaraldehyde-crosslinking chitosan scaffolds reinforced with calcium phosphate spray-dried granules for bone tissue applications.

The clinical demand for bone scaffolds as an alternative strategy for bone grafting has increased exponentially and, up to date, numerous formulations have been proposed to regenerate the bone tissue. However, most of these structures lack at least one of the fundamental/ideal properties of these materials (e.g., mechanical resistance, interconnected porosity, bioactivity, biodegradability, etc.). In this work, we developed innovative composite scaffolds, based on crosslinked chitosan with glutaraldehyde (GA), combined with different atomized calcium phosphates (CaP) granules - hydroxyapatite (HA) or biphasic mixtures of HA and β - tricalcium phosphate (β-TCP), with improved biomechanical behavior and enhanced biological response. This innovative combination was designed to improve the scaffolds' functionality, in which GA improved chitosan mechanical strength and stability, whereas CaP granules enhanced the scaffolds' bioactivity and osteoblastic response, further reinforcing the scaffolds' structure. The biological assessment of the composite scaffolds showed that the specimens with 0.2% crosslinking were the ones with the best biological performance. In addition, the inclusion of biphasic granules induced a trend for increase osteogenic activation, as compared to the addition of HA granules. In conclusion, scaffolds produced in the present work, both with HA granules or the biphasic ones, and with low concentrations of GA, have shown adequate properties and enhanced biological performance, being potential candidates for application in bone tissue engineering.

Fish biowaste gelatin coated phosphate-glass fibres for wound-healing application

Inadequate wound management techniques can result in severe consequences for patients and are a major Health Economic burden worldwide. Currently, biosynthetic scaffolds for wound healing are of interest to address the shortcomings of existing treatment options. Gelatin is a derivative of collagen with similar properties, however, with non-antigenic properties. Fish biowaste gelatin has been recognized as a safer, economical and more widely accepted alternative to gelatin derived from mammalian sources. This study investigated the use of bioresorbable phosphate-based glass fibres (PGFs) coated with fish scale gelatin (FSG - extracted from tilapia fish scales) for potential wound healing application. Assessments of the FSG revealed a high protein content of 89.4%. The bloom gel strength, viscosity, SDS-PAGE molecular pattern and functional groups of FSG were found to be similar to bovine gelatin. FSG was then crosslinked using relatively low concentrations of glutaraldehyde (GTA) to coat PGF surfaces. These GTA-crosslinked coated scaffolds were then evaluated in vitro for their cytocompatibility via HaCaT cell adhesion, migration and proliferation studies. All cells grown on the un-crosslinked coated (UCS) and GTA-crosslinked coated scaffolds (GCS5, GCS10 and GCS15) revealed cells with flat and spreading morphologies along the fibres. However, only GCS15 samples showed a significantly greater number of adhered cells than the uncoated PGFs. GCS10 and GCS15 both revealed accelerated in vitro artificial wound closure via additional 27.4% and 28.5% (µm/µm), respectively in wound scratch test, as compared to the untreated wound within 24 h. Tetrazolium (MTT) assay revealed the highest cell viability in GCS15 among all the scaffolds on day 7. Overall, GCS15 promoted adhesion and proliferation of HaCaT cells and ultimately, accelerated their migration in vitro demonstrating high potential of this material as a wound healing scaffold.

Decellularization as a method to reduce calcification in bovine pericardium bioprosthetic valves.

Decellularization is an alternative method for processing biological tissues with decreased antigenicity and resistance to calcification. The aim of this study was to characterize the properties of decellularized (dCell) bovine pericardium fixed with 0.1% glutaraldehyde (GA) and to evaluate outcomes of bioprosthetic valves constructed with this tissue when implanted in the mitral position of juvenile sheep. Bioprosthetic mitral valves were constructed with fresh bovine pericardium fixed in 0.5% GA (control group) or dCell bovine pericardium fixed in 0.1% GA (study group). Before implantation, samples were submitted to histological (haematoxylin-eosin, Movat and 4',6-diamidino-2-phenylindole), biochemical (residual deoxyribonucleic acid and α-gal epitopes) and biomechanical characterization. Valves were implanted (n = 8 in each group) as a mitral valve replacement for 180 days in sheep and explants were re-evaluated histologically and for calcification with radiological studies and calcium content determination. Unimplanted dCell pericardia exhibited a well-preserved extracellular matrix with absence of cells, a 77% reduction in deoxyribonucleic acid levels and with no detectable α-gal epitopes. When compared to controls, they had lower ultimate tensile strength (7.3 ± 5.4 vs 10.2 ± 3.0 mPa, P = 0.04) and greater percentage elongation in the longitudinal direction (29 ± 6.5% vs 23.8 ± 5.1%, P = 0.02). After 180 days in mitral position, dCell valves showed pliable leaflets without macroscopic signs of calcification. Histologically, dCell leaflets had intact collagen fibres, better tissue remodelling and a significant 89% reduction in calcium content. This study demonstrates that bioprosthetic valves constructed with dCell bovine pericardium fixed in low GA concentration were resistant to calcification and may thereby improve long-term durability of the tissue.

Antibacterial activity of Staphylococcus aureus biofilm under combined exposure of glutaraldehyde, near-infrared light, and 405-nm laser.

Healthcare-associated infections have increasingly become problematic in the endoscopic procedures resulting in several severe diseases such as carbapenem-resistant Enterobacteriaceae (CRE)-related infections, pneumonia, and bacteremia. Especially, some bacterial strains are resistant to traditional antimicrobials. Therefore, the necessity of developing new antibiotics or management to deal with bacterial infections has been increasing. The current study combined a low concentration of glutaraldehyde (GTA) with near-infrared (NIR) light and 405-nm laser to entail antibacterial activity on Staphylococcus aureus biofilm. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and colony forming unit (CFU) counting were used to quantify the viable cells while fluorescent and scanning electron microscopic images were used to qualitatively evaluate the cell membrane integrity and structural deformation, respectively. Practically, S. aureus biofilm was highly susceptible (7% cell viability and 6.8-log CFU/cm2 bacterial reduction for MTT assay and CFU analysis, respectively) to the combination of GTA (0.1%), NIR light (270 J/cm2), and 405-nm laser (288 J/cm2) exposure. GTA could form either DNA-protein or protein-protein crosslinks to inhibit DNA and protein synthesis. The NIR light induced the thermal damage on protein/enzymes while 405-nm laser could induce reactive oxygen species (ROS) to damage the bacterial membrane. Thus, the proposed technique may be a feasible modality for endoscope cleaning to prevent any secondary infection in the healthcare industry.

Synergism between high hydrostatic pressure and glutaraldehyde for the inactivation of Staphylococcus aureus at moderate temperature.

The sterilization of transplant and medical devices should be effective but not detrimental to the structural properties of the materials used. In this study, we examined the effectiveness of chemical and physical agents for inactivating Staphylococcus aureus, a gram-positive bacterium and important cause of infections and biofilm production. The treatment conditions in this work were chosen to facilitate their subsequent use with sensitive materials. The effects of temperature, high hydrostatic pressure, and glutaraldehyde disinfectant on the growth of two strains of S. aureus (ATCC 25923 and BEC 9393) were investigated individually and/or in combinations. A low concentration of glutaraldehyde (0.5mM), high hydrostatic pressure (300MPa for 10min), and moderate temperature (50°C), when used in combination, significantly potentiated the inactivation of both bacterial strains by > 8 orders of magnitude. Transmission electron microscopy revealed structural damage and changes in area that correlated with the use of pressure in the presence of glutaraldehyde at room temperature in both strains. Biofilm from strain ATCC 25923 was particularly susceptible to inactivation. The conditions used here provided effective sterilization that can be applied to sensitive surgical devices and biomaterials, with negligible damage. The use of this experimental approach to investigate other pathogens could lead to the adoption of this procedure for sterilizing sensitive materials.

Erythrocyte Rigidity Affects Blood Clot Contraction and Formation of Polyhedrocytes

Blood clot contraction or retraction has been implicated to play a significant role in hemostasis, reduction of thrombus volume, and wound healing. Clot contraction is driven by forces that are generated by platelets and transmitted by fibrin and results in volume shrinkage followed by the compaction of erythrocytes into the core of the blood clot, resulting in their mechanical deformation towards a polyhedral shape, giving rise to the term polyhedrocytes. Despite the fact that erythrocytes are a major component of blood clots, relatively little is known about the influence of the mechanical properties or deformability of erythrocytes on the process of clot contraction. Increased hematocrit reduces extent of clot contraction due to mechanical resilience of erythrocytes and it is likely that in addition to a volume fraction the stiffness of erythrocytes can also affect the extent and rate of clot contraction. Here we tested this assumption by using artificially or naturally stiffened erythrocytes that have pathophysiological implications. The reduced deformability of erythrocytes is associated with a number of pathological conditions, such as hypertension, diabetes mellitus, atherosclerosis and smoking, but perhaps one of the most well-known diseases associated with increased erythrocyte rigidity is sickle cell disease (SCD). Another example of naturally stiff erythrocyte membrane is that of llama or camel that have red blood cells with increased osmotic resistance.To assess the extent of clot contraction, we used an optical tracking methodology that allows for the quantitative tracking for clot size. To assess the influence of erythrocyte rigidity on clot contraction we also used scanning electron microscopy to evaluate deformations of the erythrocytes, including the presence of polyhedrocytes. Centrifugation of citrated blood can be used to mimic the contractile forces generated by platelets and has been shown to cause polyhedrocyte formation. Increasing the erythrocyte rigidity through their treatment with a low concentration of glutaraldehyde resulted in a decrease in polyhedrocyte formation and the requirement of larger centrifugal forces to observe erythrocyte deformation, suggesting that the mechanical properties of erythrocytes could influence the process of clot contraction. As residual glutaraldehyde may have unwanted effects on platelets, clot contraction experiments were completed using naturally stiffer erythrocytes from SCD patients and llama ovalocytes, which are stiffer than human erythrocytes due to the increased amount of the membrane cytoskeletal protein spectrin. SCD patients were only included in this study if they had Sickle Trait, SCD Hb SS, SCD Hb SC and have not received recent transfusions. The blood samples of SCD patients were examined and on average had a 53% decrease (p<0.0001) in the extent of clot contraction compared to healthy subjects. Likewise, addition of llama ovalocytes to human platelet rich plasma resulted in a 28% decrease in extent of clot contraction compared to human erythrocytes and larger centrifugal forces were needed to see red cell deformation. SCD patients contracted 2.4X slower (p<0.001) during linear contraction (Phase 2) and 2.7X slower (p<0.05) during mechanical stabilization (Phase 3) when compared to healthy subjects. Clot contraction was impaired also by erythrocytes treated with antibodies that bind to the Wright b epitope on the erythrocytes and exert a rigidifying effect on the cells. The binding of the antibody to erythrocytes was determined by flow cytometry and the KD was ~50 nM. Increased red blood cell rigidity following exposure to antibodies was confirmed through mechanical and osmotic resistance and compared to unaltered erythrocytes.Collectively, these results demonstrate that erythrocyte mechanical properties can influence the process of clot contraction so that stiffer cells reduce the rate and extent of clot contraction. A better understanding of the role of erythrocyte deformability in the process of clot contraction has the potential to inform the development of more targeted treatments for limiting bleeding and thrombosis in patients who are prone to having altered erythrocyte content and mechanical properties of these highly abundant cells embedded into blood clots and thrombi. DisclosuresWeisel:Bayer: Research Funding.

Converting Red Blood Cells to Efficient Microreactors for Blood Detoxification.

A simple method to convert red blood cells (RBCs) into efficient microreactors is reported. Triton X-100 is employed at finely tuned concentrations to render RBCs highly permeable to substrates, while low concentrations of glutaraldehyde are used to stabilize cells. The ability for blood detoxification of these microreactors is demonstrated.

The efficiency of cell seeding on acellular heart valve scaffolds modified with low concentrations of glutaraldehyde (GA)

The efficiency of cell seeding on acellular heart valve scaffolds modified with low concentrations of glutaraldehyde (GA)

Evaluation of biodegradation and biocompatibility of collagen/chitosan/alkaline phosphatase biopolymeric membranes

The aim of this study was to develop a new variant of membranes based on collagen (COL), chitosan (CHI) and alkaline phosphatase (ALP) immobilized and cross-linking with glutaraldehyde (GA) at different concentrations. The biodegradation in the presence of collagenase was investigated. Biocompatibility was evaluated by MTT assay using a mouse fibroblast cell culture type NCTC (clone 929). Non-cross-linked samples were biocompatible and membranes cross-linked with low concentrations of GA (0.04, 0.08%) were also biocompatible. However, high concentrations of GA lead to a decreased biocompatibility. The adsorption behaviour of Ca2+ ions to all membranes were evaluated using the Freundlich isotherms. Haemolytic studies were performed in order to consider their applications in biomineralization process. By the addition of collagen and ALP to chitosan, the haemolytic index decreases, the COL–CHI–ALP membrane being in the non-haemolytic domain, while the COL–CHI–ALP–GA membrane has a haemolytic index greater than 2, and is slightly haemolytic.

Evaluation of an established pericardium patch for delivery of mesenchymal stem cells to cardiac tissue.

The present study has evaluated a commercial pericardial material for its capacity to assist as a natural extracellular matrix (ECM) patch for the delivery and retention of mesenchymal stem cells for cardiac repair. The repair of cardiac tissue with cells delivered by an appropriate bioscaffold is expected to offer a superior, long-lasting treatment strategy. The present material, CardioCel®, is based on acellular pericardium that has been stabilized by treatments, including a low concentration of glutaraldehyde, that eliminate calcification after implantation. In the present study, we have assessed this material using human bone marrow mesenchymal stem cells at various cell densities under standard, static cell culture conditions. The initial seeding densities were monitored to evaluate the extent of cell attachment and cell viability, with subsequent cell proliferation assessed up to 4 weeks using an MTS assay. Cell morphology, infiltration, and spreading were tracked using scanning electron microscopy and phalloidin staining. The efficacy of long-term cell survival was further assessed by examining the extent and type of new tissue formation on seeded scaffolds at 70 days; both type I and type III collagens were present in fibrillar structures on these scaffolds indicating that the seeded stem cells had the capacity to differentiate into collagen-producing cells necessary to repair damaged ECM. These data show that the CardioCel® scaffold is an appropriate substrate for the stem cells and has the potential to both retain seeded stem cells and to act as a template for cell propagation and new tissue formation.

Hemoglobin-Based Oxygen Carrier Microparticles: Synthesis, Properties, and In Vitro and In Vivo Investigations

Bovine hemoglobin microparticles (Hb-MPs) as suitable oxygen carriers are fabricated easily by three key steps: coprecipitation of Hb and CaCO(3) to make Hb-CaCO(3)-microparticles (Hb-CaCO(3)-MPs), cross-linking by glutaraldehyde (GA) to polymerize the Hb and dissolution of CaCO(3) template to obtain pure Hb-MPs. The Hb entrapment efficiency ranged from 8 to 50% corresponding to a hemoglobin quantity per Hb-MP of at least one-third of that in one erythrocyte. The Hb-MPs are spherical, with an average diameter of 3.2 μm and high oxygen affinity. The methemoglobin level was increased after preparation, but can be reduced to less than 7% with ascorbic acid. Phagocytosis assays showed low immunogenicity of Hb-MPs if the particles were cross-linked with low concentration of GA and treated with sodium borohydride. Magnetite-loaded Hb-MPs circulated up to 4 days after intravenous application.

Mechanical, swelling and adsorptive properties of dry–wet spun chitosan hollow fibers crosslinked with glutaraldehyde

Chitosan (CS) hollow fiber (HF) membranes were successfully prepared according to the dry–wet spinning technique. A post-treatment with glutaraldehyde (GA) aqueous solution was carried out to perform the cross-linking reaction. The effect of GA concentration in the range 50–1000mgl−1 on the swelling, mechanical and adsorptive properties was investigated. The morphology and chemical structure of the fibers were examined by means of SEM and FTIR. The degree of swelling and adsorption capacity decreased as the GA concentration increased. CS hollow fibers swelled the most in acidic solution as compared with distilled water and saline solution. The adsorption capacity of CS HFs increased while decreasing of initial pH from 7.5 to 3.5. Desorption experiments showed that CS HFs were reusable as adsorbent. Mechanical properties were strongly affected by GA post-treatment: tensile strength and elastic modulus increased at low GA concentration (50mgl−1), to sharply decrease when concentration was ⩾500mgl−1. Breaking elongation decreased with increasing GA concentration.

Quantitative evaluation of freeze-substitution effects on preservation of nuclear antigens during preparation of biological samples for immunoelectron microscopy

Using quantitative evaluation of immuno-gold labeling and antigen content, we evaluated various automated freeze-substitution protocols used in preparation of biological samples for immunoelectron microscopy. Protein extraction from cryoimmobilized cells was identified as a critical point during the freeze-substitution. The loss of antigens (potentially available for subsequent immuno-gold labeling) was not significantly affected by freezing, while the cryosubstitution with an organic solvent caused a significant loss of antigens. While addition of water can improve visibility of some cell structures, it strengthened the negative effect of cryosubstitution on antigen loss by extraction. This was, however, significantly reversed in the presence of 0.5% glutaraldehyde in the substitution medium. Furthermore, we showed that the level of these changes was antigen-dependent. In conclusion, low concentrations of glutaraldehyde can be generally recommended for cryosubstitution rather than the use of pure solvent, but the exact conditions need to be elaborated individually for certain antigens.

A Comparative Study on Mechanical and Biochemical Properties of Bovine Pericardium After Single or Double Crosslinking Treatment

Background and ObjectivesGlutaraldehyde (GA) has been used as a representative method of tissue preservation in cardiovascular surgery. However, GA has showed limited durability including calcification, mechanical failure and toxicity. To overcome those unsolved problems, we analyzed the crosslinking differences of primary amines, GA and genipin in their mechanical and biochemical properties with a single or double crosslinking agent for clinical application.Materials and MethodsSamples were divided into 3 groups; control, single crosslinking fixation and double crosslinking fixation after decellurarization using bovine pericardium. For analysis of the biochemical and mechanical properties of each crosslinking method, tensile strength, percentage strain, thermal stability, resistance to pronase, nynhydrin and cytotoxicity test were studied.ResultsCombined hexamethylene diamine and suberic acid in the carbodiimide hydrochloride/N-hydroxysucinimide solution (EDC/NHS) after decellurarization, tensile strength and strain percentage were not statistically significant compared to the single crosslinking treated groups (p>0.05). Tissue crosslinking stability was weak in single treatment of diphenylphosphoryl azide, suberic acid, low concentration of EDC, hexamethylene diamine and procyanidin groups, but thermal stability and resistance to the pronase and ninhydrin were markedly increased in concentrated EDC/NHS or after combined double treatment with low concentration of GA or genipin (p<0.001).ConclusionSingle or double crosslinking with low concentration of carbodiimide, diphenylphosphonyl azide, procyanidin, suberic acid and hexane diamine were not as effective in mechanical, biochemical, cytotoxic and crosslinking properties compared to GA or genipin fixation, but their mechanical and chemical properties were much improved when combined with low concentrations of GA or genipin in the double crosslinking process.

Preparation and characterization of plasticized gelatin films cross-linked with low concentrations of Glutaraldehyde

Thermal and mechanical properties as well as moisture resistance and water vapor barrier properties of films from bovine gelatin added with d-sorbitol (30 wt%) as plasticizer and cross-linked with low amounts of glutaraldehyde (GTA, from 0 to 2 wt%) were investigated to determine their suitability as barrier layers for flexible packaging materials. Results revealed that free amino side chain groups of gelatin decreased with GTA, confirming the occurrence of cross-linking between GTA and gelatin. The extent of cross-linking reaction in the presence of d-sorbitol was lower compared with the unplasticized counterpart suggesting that plasticizer hampers GTA to react. The glass transition temperature (Tg) as measured from differential scanning calorimetry (DSC) increased with GTA concentration owing to the formation of more reticulated materials while the incorporation of d-sorbitol led to a small reduction in this parameter due to plasticization. Increasing GTA concentration from 0 to 1 wt% provoked the enhancement of elastic modulus from 3.7 ± 0.2 to 4.9 ± 0.2 GPa. These values reduced significantly by the addition of d-sorbitol, whereas elongation at break improved in about 150%. The optimum formulation for the intended purpose was that containing 1 wt% GTA and 30 wt% d-sorbitol since it exhibited the best set of properties: total soluble mater reduced from 100 to 16%, moisture absorption decreased from 1854.1 ± 85 to 210.4 ± 8%, water vapor permeability at 65% relative humidity improved from 2.42 ± 0.27 to 0.94 ± 0.06 × 10−14 kg m Pa−1 s−1 m−2, with minor reduction in opacity and with the additional benefit of releasing only 5% of the initial GTA content.