改性壳聚糖类肝素化合物血液相容性研究

选用壳聚糖为原材料，通过改性在其主链上引入-COOH和-SO3H两种基团制备成类肝素化合物。研究反应过程中羧甲基和磺酸基取代度的影响因素及不同取代位置，不同取代度的化合物复钙时间和溶血率。结果表明，壳聚糖类肝素化合物的抗凝血性能是由甲壳糖主链上引入的-COOH和-SO3H两种基团的协同效应产生的，血液相溶性的优劣主要取决于-COOH和-SO3H两者的比例。N—CM，O—SO3H壳聚糖，当N—羧甲基取代度为0．585，O—磺酸基取代度为0．593时其抗凝血性能最优。而N—SO3H，O—CM壳聚糖，当N—磺酸基取代度为0．689，O—羧甲基取代度为0．593时，其血液相溶性最佳。     

Acetylsalicylic acid loaded poly(vinyl alcohol) hemodialysis membranes: effect of drug release on blood compatibility and permeability

Membranes developed from poly(vinyl alcohol) (PVA) have superior permeability because of the highly hydrophilic character of PVA. However, its blood compatibility needs to be further improved. For this we have developed acetylsalicylic acid (ASA, aspirin) loaded PVA membranes. It seems that the slow release of aspirin from the membrane provides a surface concentration of aspirin sufficient for partially inhibiting platelet adhesion. PVA membrane with 531 μg cm-2 of ASA loaded, may be selected for hemodialysis applications. This may help to reduce the amount of heparin infused during hemodialysis, thereby reducing the side-effects associated with the systemic administration of heparin.     

Surface characteristics and blood compatibility of polyurethanes grafted by perfluoroalkyl chains

Polyurethane (PU) surface was chemically modified by grafting of perfluorodecanoic acid (PFDA) to produce a highly hydrophobic surface to compare the blood compatability with hydrophilic poly(ethylene oxide) (PEO) grafted PUs. The advancing contact angle of modified PU-PFDA was increased up to 115 deg, while that of untreated PU was 86 deg. The PFDA grafted PU exhibited less adhesion and shape change of platelets than untreated PU, and the activated partial thromboplastin time (APTT) of PU-PFDA was considerably extended. The ex vivo occlusion time of untreated PU was only 50 min, but that of PFDA grafted PU was extended to 130 min, indicating that this hydrophobic surface is significantly blood compatible. It is interesting to find that the enhanced blood compatibility of very hydrophobic PU-PFDA was equivalent to hydrophilic PU-PEO.     

Gas transfer and blood compatibility of fluorinated polyimide membranes

Fluorinated polyimide derived from 2,2'-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and bis[4-(4-aminophenoxy) phenyl]sulfone (APPS) was synthesized to develop a novel membrane oxygenator combining excellent gas transfer and blood compatibility. The asymmetric gas exchange membranes of 6FDA-APPS made by a dry/wet process consisted of an ultrathin and defect-free skin layer supported by a porous substructure. O₂ transfer through the 6FDA-APPS membrane was extremely augmented as compared with that of the presently available membrane, poly(dimethylsiloxane), and the previously reported 6FDA-DDS membrane. Since CO₂ transfer through the 6FDA-APPS membrane increased with a decrease in CO₂ pressure according to dual-mode transport theory, CO₂ from the membrane was selectively removed at low CO₂ pressure. For the evaluation of in vitro blood compatibility, the platelet adhesion and the plasma protein adsorption on the surface of the 6FDA-APPS membrane were observed by using scanning electron microscopy and the amounts of platelet and plasma protein were determined by an amino acid analyzer. The results indicated that the fluorinated polyimide membranes showed excellent blood compatibility.     

肝素在人工小血管表面改性中的应用

人工小血管因为其抗凝血性能不佳的原因并没有大量应用于临床,肝素化修饰是目前最为理想的增加材料表面抗凝血性能的方法之一。本文介绍肝素的结构及性能,并简述共价修饰、离子键和物理缓释这3个目前主要的肝素改性方法,同时总结各种方法的优缺点并对肝素在人工血管改性的未来方向进行展望。     

Surface modification of a segmented polyetherurethane using a low-powered gas plasma and its influence on the activation of the coagulation system

A medical grade segmented polyetherurethane (PEU) was treated with a low-powered gas plasma using O₂, Ar, N₂ and NH₃ as the treatment gases. Changes in the surface functional group chemistry were studied using X-ray photoelectron spectroscopy. The wettability of the surfaces was examined using dynamic contact angle measurements and the surface morphology was evaluated using atomic force microscopy. The influence of the surface modification to the polyurethane on the blood response to the polyetherurethane was investigated by measuring changes in the activation of the contact phase activation of the intrinsic coagulation cascade. The data demonstrate that the plasma treatment process caused surface modifications to the PEU that in all cases increased the polar nature of the surfaces. O₂ and Ar plasmas resulted in the incorporation of oxygen-containing groups that remained present following storage in an aqueous environment. N₂ and NH₃ plasmas resulted in the incorporation of nitrogen-containing groups but these were replaced with oxygen-containing groups following storage in the aqueous environment. In all plasma treatments there was a lowering of contact phase activation compared to the untreated surface, the N₂ and NH₃ treatments dramatically so.     

Immobilization of Heparin on the Surface of Polypropylene Non-Woven Fabric for Improvement of the Hydrophilicity and Blood Compatibility

Abstract

A polypropylene non-woven fabric (PPNWF) was exposed to oxygen plasma to produce peroxides on its surface. These peroxides were used to initiate graft polymerization of acrylic acid (AA) on the surface of PPNWF. Direct heparinization was accomplished via a reaction between heparin and PP-PAA (AA grafted PPNWF) which was activated by EDC (N-ethyl-N’-[3-(dimethylamino)propyl] carbodiimide). Indirect heparinized PPNWF was prepared by grafting poly(ethylene oxide) (PEO) on a PP-PAA surface to form PP-PAA-PEO, followed by reaction with heparin which was activated by EDC before use. The surface modified PPNWFs were characterized by attenuated total reflection Fourier transform infrared (ATR–FT-IR) spectroscopy, electron spectroscopy for chemical analysis (ESCA) and contact angle goniometry. It was found that hydrophilicity was greatly improved, as indicated by the decrease of the water contact angle from 142 to 33°. In vitro blood compatibility evaluation of modified PPNWFs, including hemolysis rate, platelet adhesion, plasma protein adsorption and activated partial thromboplastin time (APTT) was investigated. The results suggested that both heparinized PPNWFs showed lower hemolysis rates and better platelet anti-adhesion than non-heparinized controls. Furthermore, PPNWF obtained via indirect immobilization of heparin showed better hydrophilicity and blood compatibility than direct heparinization of PPNWF.     

Surface modification of plastic, glass and titanium by photoimmobilization of polyethylene glycol for antibiofouling

Photoreactive poly(ethylene glycol) (PEG) was prepared and the polymer was photoimmobilized on organic, inorganic and metal surfaces to reduce their interaction with proteins and cells. The photoreactive PEG was synthesized by co-polymerization of methacrylate-PEG and acryloyl 4-azidobenzene. Surface modification was carried in the presence and the absence of a micropatterned photomask. It was then straightforward to confirm the immobilization using the micropatterning. Using the micropatterning method, immobilization of the photoreactive PEG on plastic (Thermanox™), glass and titanium was confirmed by time-of-flight secondary ion mass spectroscopy and atomic force microscopy observations. The contact angle on an unpatterned surface was measured. Although the original surfaces have different contact angles, the contact angle on PEG-immobilized surfaces was the same on all surfaces. This result demonstrated that the surface was completely covered with PEG by the photoimmobilization. To assess non-specific protein adsorption on the micropatterned surface, horseradish peroxidase (HRP)-conjugated proteins were adsorbed. Reduced protein adsorption was confirmed by vanishingly small staining of HRP substrates on the immobilized regions. COS-7 cells were cultured on the micropatterned surface. The cells did not adhere to the PEG-coated regions. In conclusion, photoreactive PEG was immobilized on various surfaces and tended to reduce interactions with proteins and cells.     

Evapomeation characteristics of cross‐linked quaternized chitosan membranes for the separation of an ethanol/water azeotrope

The permeation and separation characteristics during evapomeation of an ethanol/water azeotrope (96.5 wt.‐% ethanol) through quaternized chitosan (q‐Chito) membranes and cross‐linked q‐Chito membranes, which were cross‐linked with diethylene glycol diglycidyl ether (DEDGE), were studied. Both the q‐Chito and the cross‐linked q‐Chito membranes showed high water‐permselectivity for an ethanol/water azeotrope. The permeation rates for both membranes decreased and the water‐permselectivities increased, with an increasing degree of quaternization of the chitosan and cross‐linker concentration. The mechanism of separation for the ethanol/water azeotrope through the q‐Chito and cross‐linked q‐Chito membranes was analyzed by the solution‐diffusion model. Increasing permeation temperature increased the permeation rate and decreased the water‐permselectivity for both membranes. However, the permeation rates of a cross‐linked q‐Chito membrane at 60–80°C were almost the same as those of the q‐Chito membrane, and the separation factors for water‐permselectivity (α =4 100–4 200) in the former were greater by two orders of magnitude as compared to the latter (α = 47–58). The above results were discussed from the viewpoints of the physical and chemical structure of the q‐Chito and cross‐linked q‐Chito membranes.

Effects of the degree of quaternization on the separation factor (□), the sorption selectivity (○), and the diffusion selectivity (•) for an ethanol/water azeotrope using the q‐Chito membranes.     

血容量监测的方法及其在血液透析中的应用

随着血液透析在临床中的大量应用,对患者血容量实时监测已成为近年来透析机领域的一项重要工作。血容量监测可以实时提供患者相对血容量信息,对了解患者的水合状态、预防症状性低血压和难治性高血压、调整干体重、制定透析方案具有重要的临床指导意义。本文主要介绍了几种血容量监测方法及血容量监测在临床治疗中的应用价值,并指出目前存在的问题及今后的研究方向。     

Utilization of the platelet release reaction in the blood compatibility assessment of polymers

The release reaction is directly associated with platelet adhesion and aggregation, which are primary events leading to thrombus formation following contact of blood with artificial surfaces. This investigation examined the release reaction from the alpha granules of platelets after blood-polymer interaction, and utilized the measurement of beta-thromboglobulin (BTG), a platelet-specific protein, in the assessment of the in vitro blood compatibility of polymers. A radioimmunoassay was used, to determine the release of BTG following contact of blood with tubes of siliconized glass and polypropylene and flat sheets of poly(vinyl chloride) and silicone rubber. Polypropylene tubes caused less release of BTG than those of siliconized glass and silicone rubber induced less BTG release than poly(vinyl chloride). The investigation indicates a role for BTG measurement in blood compatibility assessment.     

层层静电自组装表面修饰静电纺丝人工血管的生物相容性研究

背景大、中口径人工血管已成功用于临床,但是由于材料的疏水性小口径人工血管仍不能满足临床的需要。因此,提高人工血管材料的亲水性、抗凝血性一直是医学界研究的热点。目的研究静电自组装修饰后的电纺丝纤维膜的形貌特征、细胞相容性和组织相容性。方法利用静电自组装技术将壳聚糖和肝素修饰到静电纺丝聚乳酸纤维膜表面,通过扫描电镜观察组装前后电纺丝纤维的形貌特征;将人脐静脉内皮细胞种植与组装前后的纤维膜上,通过MTT测试检测细胞增殖能力;通过将组装前后不同材料植入兔皮下15天,通过HE染色检测其组织相容性。结果 SEM结果显示,成功将壳聚糖/肝素组装到电纺丝纤维膜表面。MTT结果显示组装后的电纺丝纤维膜促进HUVEC的增殖。兔皮下植入实验结果显示组装修饰后的电纺丝膜具有良好的组织相容性。结论静电自组装成功应用于静电纺丝中,并且电纺丝纤维膜经修饰后成功提高材料的细胞相容性和组织相容性。     

Increased whole blood chemiluminescence in patients with chronic renal failure independent of hemodialysis treatment

Introduction: The luminol-enhanced whole blood chemiluminescence (LBCL) assay is a rapid assay for the measurement of reactive oxygen species (ROS) generation by circulating phagocytes. This study’s aim was to determine if patients on maintenance hemodialysis (HD) and non-dialyzed patients with chronic renal failure (CRF) have altered LBCL and if dialysis itself affects ROS production in the blood. Materials and Methods: Twenty-six HD patients, 11 non-dialyzed patients with CRF, and 20 gender- and age-matched healthy controls were studied. Resting (rCl) and 2 × 10⁻⁵ M n-formyl-methionyl-leucyl-phenylalanine-stimulated LBCL (peak chemiluminescence: pCl, total light emission after agonist addition: tCl) calculated per 10⁴ phagocytes present in the 3-μl blood samples were measured with a Bio-Orbit^? 1251 luminometer at 37°C for 11 min. Results: Prior to the HD session, median rCL, pCL, and tCL were 1.5, 3.0, and 2.8 times higher in HD patients than in healthy controls (p<0.01) and tended to increase at the end of the session. Significant increases in tCl were observed at 30 min and 240 min (end) of HD (1023.5 vs. 1810.6 vs. 2006.8 arbitrary units × s/10⁴ phagocytes, n=9, p<0.05). Median pCl and tCl were 5.0 and 4.3 times higher in non-dialyzed patients with CRF than in healthy controls (p<0.001). However, no significant differences were found between pre- and post-HD LBCL of HD patients and the LBCL of non-dialyzed patients with renal failure. Conclusions: Blood from patients with renal failure generates elevated amounts of oxidants independently of HD treatment. This may add to the understanding of the nature of oxidative stress and suggests the need of anti-oxidant treatment in these patients.     

Surface tension measurement of normal human blood samples by pendant drop method

Abstract

The surface tension of blood plays an important role not only in the birth and decompression sickness but also in other functionality of the organism. It also provides capillary action during blood flow process. In this article, a simple and low-cost device is designed and fabricated for measuring the surface tension of blood by pendant drop method. In this device, a droplet of blood is formed in a closed chamber on tip of an 18-gauge blunt needle and it is photographed by a camera in very humid conditions (RH = 99%) to minimise the evaporation. A wetted wick is provided at the bottom of the chamber for maintaining constant relative humidity in chamber. Surface tension of blood is inferred using drop shape factor method and image analysis technique at various experimental conditions. This device is validated and calibrated with surface tension measurements of water and silicone oil. Its measurements are in good agreement against data reported in literature. Post-validation, surface tensions of blood samples with and without anticoagulant of healthy persons at various temperatures (range from 20 to 40?°C) was measured. It was found that the surface tension of normal blood samples strongly correlates with blood temperature. The surface tension of female blood was remarkably different from same of male blood. However, the effect of age (21–60?year) on the surface tension was negligible for all practical purposes. Increased percentage of anticoagulant in blood increases its surface tension. This research specifies a baseline for surface tension of normal blood samples at various conditions which in turn provides new insights to pathologists in identifying various disease conditions.     

Effect of methylene chain length in phospholipid moiety on blood compatibility of phospholipid polymers

To investigate the effects of the methylene chain length between the phospholipid polar group and the backbone on blood compatibility of a phospholipid polymer, copolymers of ω-methacryloyloxyalkyl phosphorylcholine (MAPC) with n-butyl methacrylate (BMA) were synthesized. The methylene chains were ethylene (n = 2), tetramethylene (n = 4), and hexamethylene (n = 6). Every MAPC copolymer with an MAPC mole fraction in the range of 0.1-0.3 was soluble in ethanol but only swelled in water, and the equilibrium water fraction of the water-swollen MAPC copolymer membrane decreased with the length of the methylene chain. When a rabbit platelet-rich plasma was applied on the MAPC copolymer surface with an 0.1 MAPC mol fraction for 180 min, the number of adhered platelets depended on the length of the methylene chain in the MAPC moiety of the copolymer. The amount of phospholipid adsorbed on the MAPC copolymer from human plasma was larger than that on hydrophobic poly(BMA) and increased with the length of the methylene chain in the MAPC moiety. That is, the reduction of platelet adhesion corresponded to the increase in the amount of phospholipid adsorbed on the MAPC copolymer.     

Adsorption of plasma proteins to DMAA hydrogels obtained by ionizing radiation and its relationship with blood compatibility

The interaction of plasma proteins such as albumin, γ-globulin, and fibrinogen with the surface of graft copolymers DMAA-G-PTFE, DMAA-G-PETFE, and DMAA-G-PE obtained by radiation graft polymerization was studied. The adsorption of serum proteins was affected by the hydrophilicity of the graft copolymers. Increased albumin adsorption and decreased fibrinogen and γ-globulin adsorption with increasing grafting levels was shown. A certain range of degrees of grafting showed an improved blood compatibility of the polymeric surfaces due to the existence of a hydrophilic/hydrophobic balance on the polymers. The results suggest that the DMAA-G-PTFE, DMAA-G-PETFE, and DMAA-G-PE graft copolymers can be used as biomaterials for long-term use in cardiovascular systems.     

Stabilization of red blood cell membranes by thalidomide in vitro

The anti-inflammatory effect of thalidomide has been well established. The mechanism of this anti-inflammatory action is still not completely understood. Certain drugs exert their anti-inflammatory action by stabilizing the membranes of polymorphonuclear neutrophils (PMN) thereby reducing the production of reactive oxygen intermediates. We evaluated the effect of thalidomide on cell membranes by using red blood cells (RBC), PMN and the monocyte-like cell line THP-1. Osmotic fragility of RBC showed that in vitro, thalidomide stabilized the membrane of RBC from plasma free blood; whereas, it did not affect RBCs from whole blood. Red blood cells taken from subjects before and after ingestion of thalidomide were not affected after exposure to different concentrations of hypotonic NaCl solution. Thalidomide did not affect the membrane stability of PMNs as well as THP-1 in a significant manner. These data suggest that the anti-inflammatory mechanism of thalidomide is not related to events associated with the oxidative burst of PMNs or monocytes.     

Laser surface modification of silicone rubber to reduce platelet adhesion in vitro

To improve the blood compatibility, the surface of polydimethylsiloxane (PDMS) films were irradiated using a CO₂-pulsed laser. Acrylamide (AAm) was grafted onto a pre-irradiated surface. The AAm-grafted and laser-treated films were characterized using different techniques. Platelet adhesion and activation onto the AAm-grafted PDMS, laser-treated (ungrafted) and unmodified PDMS film surfaces were compared. Data from in vitro assays indicated that the platelet adhesion was reduced on the AAm-grafted PDMS and laser treated PDMS films in comparison with the unmodified PDMS. The laser-irradiated sample showed the minimum platelet adhesion. It seems that laser irradiation onto a silicone rubber surface is a versatile technique to produce anti-thrombogenic surface for biomaterial applications.     

Adsorption of albumin on flax fibers increases endothelial cell adhesion and blood compatibility in vitro

The physical and chemical properties of flax (linen) are attractive from the perspective of biomaterials science and engineering. Flax textiles uniquely combine hydrophilicity and strength, with the technical know-how to produce precisely engineered two- and three-dimensional knitted or woven structures. It is, however, extremely difficult to completely remove endotoxins from the flax, and this essentially precludes the use of linen for implant purposes. Herein, the potential utility of flax textiles for blood-contacting applications is investigated, using purified two-dimensional mesh specimens, with and without an albumin surface coating. It was hypothesized that the albumin coating will abolish the effect of adherent endotoxins at the flax’s surface. In vitro cell viability assays showed that the flax mesh?±?albumin is not cytotoxic. The albumin coating reduced (but not abolished) the effect of surface-exposed endotoxins (Limulus amebocyte lysate test). Under dynamic conditions, the albumin coating favors coverage with endothelial cells. Experiments with fresh human blood plasma (platelet-rich and platelet-free) showed that the albumin coating reduces the thrombogenicity in vitro. Platelets adhered to the albumin-coated flax mesh showed a less flattened structure. Although the results of this work cannot be extrapolated easily to in vivo situations, the data reveal that woven or knitted tubular structures produced from flax fibers may hold promise as implantable blood contacting devices like for instance vascular grafts.     

LGDP改性人工心瓣材料抗细菌粘附的研究

本实验是在Ｎ２低温等离子体技术（ＬＧＤＰ）对Ｄａｃｒｏｎ材料表面改性的基础上进行的。用非反应性气体Ａｒ作载气,在其表面引入一些亲水基团,接枝抗细菌粘附的聚乙二醇和肝素。对改性后的材料作体外表皮葡萄球菌（Ｓｔａｐｈｙｌｏｃｏｃｃｕｓ Ｅｐｉｄｅｒｍｉｄｉｓ,ＳＥ）的动态粘附实验,其抗细菌粘附的能力有较为明显的提高,与未改性材料相比,细菌粘附减少８０％以上。