Cellulose Acetate Dialysis Membrane Research Articles

Preparation of guanidinylated carboxymethyl chitosan and its application in the diffusive gradients in thin films (DGT) technique for measuring labile trace metals in water

ABSTRACTGuanidinylated carboxymethyl chitosan (GCMCS) was prepared via the guanidinylation of carboxymethyl chitosan (CMCS). A device employing the diffusive gradients for thin films (DGT) technique was made using a GCMCS aqueous solution as the binding agent and a cellulose acetate dialysis membrane (CADM) as the diffusion phase to measure labile Cu2+, Pb2+ and Cd2+ in water. The percentage uptake (U%) values of labile Cu2+, Pb2+ and Cd2+ in a synthetic water sample were almost consistent with the theoretical values at 101.6 ± 2.8%, 104.6 ± 6.1% and 95.9 ± 4.4%, respectively. The optimum pH ranges for the measurement of labile Cu2+, Pb2+ and Cd2+ were 3.0–7.0, 3.0–7.0 and 4.0–8.0, respectively. The ionic strength mainly affected the diffusion of metal ions in the CADM. The diffusion rates decreased with increasing concentrations of NaNO3 solutions. The application of GCMCS-DGT in natural water and industrial wastewater showed that dissolved organic carbon (DOC) only affects metal species, and the accurate determination of labile Cu2+, Pb2+ and Cd2+ can be achieved when the diffusion coefficients of these metal ions in the diffusion phase have been determined. GCMCS is suitable for DGT application as a chelating agent for metal ions.

Detection of Trace Glucose on the Surface of a Semipermeable Membrane Using a Fluorescently Labeled Glucose-Binding Protein: A Promising Approach to Noninvasive Glucose Monitoring

Our motivation for this study was to develop a noninvasive glucose sensor for low birth weight neonates. We hypothesized that the underdeveloped skin of neonates will allow for the diffusion of glucose to the surface where it can be sampled noninvasively. On further study, we found that measurable amounts of glucose can also be collected on the skin of adults. Cellulose acetate dialysis membrane was used as surrogate for preterm neonatal skin. Glucose on the surface was collected by saline-moistened swabs and analyzed with glucose-binding protein (GBP). The saline-moistened swab was also tested in the neonatal intensive care unit. Saline was directly applied on adult skin and collected for analysis with two methods: GBP and high-performance anion-exchange chromatography (HPAEC). The amount of glucose on the membrane surface was found (1) to accumulate with time but gradually level off, (2) to be proportional to the swab dwell time, and (3) the concentration of the glucose solution on the opposite side of the membrane. The swab, however, failed to absorb glucose on neonatal skin. On direct application of saline onto adult skin, we were able to measure by HPAEC and GBP the amount of glucose collected on the surface. Blood glucose appears to track transdermal glucose levels. We were able to measure trace amounts of glucose on the skin surface that appear to follow blood glucose levels. The present results show modest correlation with blood glucose. Nonetheless, this method may present a noninvasive alternative to tracking glucose trends.

Preparation Of Cellulose Acetate Dialysis Membrane Using D–Glucose Monohydrate As Additive

Dialisis membran yang mengandungi sellulosa asetat (CA) sebagai polimer, asid formik (FA) sebagai pelarut dan glukosa-D monohidrat sebagai bahan tambah telah disediakan melalui proses fasa balikan. Objektif utama bagi penyelidikan ini adalah untuk menyelidik pengaruh bahan tambah glukosa–D terhadap prestasi membran dialisis dari segi pemisahan urea dan kreatinina. Kepekatan glukosa–D diubah daripada 2 hingga 10 wt%. Pemanasan menggunakan ketuhar mikrogelombang yang dapat memendekkan masa pelarutan digunakan untuk melarutkan CA polimer dalam pelarut asid formik. Keputusan menunjukkan bahawa membran yang dihasilkan daripada 20 wt% selulosa asetat, 70 wt% asid formik dan 10 wt% glukosa–D monohidrat memberi prestasi yang terbaik bagi penyingkiran urea and kreatinina sebanyak masing–masimg 49.77% dan 19.54%. Apabila membran yang sama dikaji bagi penahanan BSA, ia memberikan peratus penyingkiran larutan BSA sebanyak 96.78%. Berbanding dengan membran dialisis selulosa asetat komersial, didapati bahawa keputusan adalah memuaskan. Gambar SEM menunjukkan bahawa penambahan glukosa–D monohidrat dalam larutan memberi pembentukan struktur jejari. Kata kunci: Membran dialisis; selulosa asetat; penyingkiran urea; penyingkiran kreatinina; peratus penahanan BSA Dialysis membrane containing cellulose acetate (CA) as polymer, formic acid (FA) as solvent and D–glucose monohydrate as additive was prepared by phase inversion method. The main objective of this study is to investigate the influence of D–glucose monohydrate as an additive on the performance of dialysis membrane in terms of urea and creatinine clearance. The concentration of D–glucose is varied from 2 to 10 wt%. Microwave heating which is capable of reducing dissolution time was used to dissolve the CA polymer in the formic acid solvent. Results revealed that the membrane produced from the 20 wt% cellulose acetate, 70 wt% formic acid and 10 wt% D–glucose monohydrate gives the best performance with urea and creatinine clearance of 49.77% and 19.54% respectively. When testing the same membranes with BSA solutions, it gives a BSA rejection rate as high as 96.78%, which seems to be comparable with the commercial cellulose acetate dialysis membranes. Membrane morphology was observed by using a scanning electron microscopy (SEM). The SEM images illustrated that the increment of D–glucose monohydrate in casting solution tends to promote macrovoid formation. Key words: Dialysis membrane; cellulose acetate; SEM images; urea clearance; creatine clearance; BSA rejection rate

Preparation and characterization of a novel smart polymeric hydrogel for drug delivery of insulin.

Over the past years, temperature and pH-sensitive hydrogels was developed as suitable carriers for drug delivery. In this study temperature and pH-sensitive hydrogels was designed for an oral insulin delivery modeling. NIPAAm-MAA -HEM copolymers were synthesized by radical chain reaction with 86:4:10 (5% w/v) ratios respectively. Reaction was carried out in 1,4-Dioxane under Nitrogen gas-flow. The copolymers were characterized with FT-IR, 1H-NMR and DSC. Copolymers were loaded with regular insulin by modified double emulsion method with ratio of 1:10. Release study carried out in two different pH (pH=2 and 7.4 for stomach and intestine simulation respectively) at 37ºC. For each pH, a 5 mL suspension of the insulin containing hydrogel was taken in to a cellulose acetate dialysis membrane, and the dialysis membrane was allowed to float in a beaker containing 15 mL of buffer solution. The beakers were placed in a shaker incubator maintained at 37ºC. Phosphate buffer (0.1 M, pH 3)/ acetonitrile (60/40) was used as the mobile phase in HPLC assay. Yield of reaction was 86% with an optimum Lower Critical Solution Temperature point (30ºC). In-vitro studies showed a control release behavior via pH changes which the amount of insulin releases was 80% and 20% at pH=2 and 7.4 respectively. Results showed that by optimizing polymerization and loading method we could achieve a suitable nano system for oral delivery of insulin.

Effective concentration difference model to study the effect of various factors on the effective diffusion coefficient in the dialysis membrane

Cellulose acetate dialysis membrane (CDM) has been used in the diffusive gradients in thin films (DGT) technique, where accurate diffusion coefficients are essential for the assessment of the concentrations of labile metal in solution. Effective concentration difference model (ECDM), based on the assumption that the effective diffusion coefficient of metal ion in the dialysis membrane is determined by the effective concentration difference (Δ C e) across the dialysis membrane, is proposed and applied to study the effect of ionic strength, binding agent, ligands and Donnan potential on the effective diffusion coefficient. The effective diffusion coefficients of Cd 2+ through the dialysis membrane immersed in receptor solutions with binding agent were almost the same as those in receptor solutions without binding agent at higher ionic strengths (0.01–1 M) but much higher than those at lower ionic strengths (0.001–0.0001 M). The effective diffusion coefficients of Cd 2+ through the dialysis membrane immersed in deionized water receptor solutions with binding agent were not significantly different from those in synthetic receptor solutions (receptor solutions with various ionic strengths) with binding agent. The DGT-labile fractions were measured in synthetic solutions and natural waters, which indicated that the effective diffusion coefficients, through the dialysis membrane immersed in the deionized water solution with binding agent as receptor solution and in the spiked natural water as source solution, were more suitable for DGT application.

Analysis of inorganic cations in biological samples by the combination of micro‐electrodialysis and capillary electrophoresis with capacitively coupled contactless conductivity detection

Micro-electrodialysis (μED) and CE were combined for rapid pretreatment and subsequent determination of inorganic cations in biological samples. Combination of μED with CE greatly improved the analytical performance of the latter as the adsorption of high molecular weight compounds present in real samples on the inner capillary wall was eliminated. Fifty microliter of 80-fold diluted human body fluids such as plasma, serum and whole blood was used in the donor compartment of the μED system requiring less than 1 μL of the original body fluid per analysis. Inorganic cations that migrated through a cellulose acetate dialysis membrane with molecular weight cut-off value of 500 Da were collected in the acceptor solution and were then analyzed using CE-C⁴D. Baseline separation of inorganic cations was achieved in a BGE solution consisting of 12.5 mM maleic acid, 15 mM L-arginine and 3 mM 18-crown-6 at pH 5.5. Repeatability of the CE-C⁴D method was better than 0.5% and 2.5% for migration times and peak areas, respectively; limits of detection of all inorganic cations in the presence of 2 mM excess of Na(+) were around 1 μM and calibration curves were linear with correlation coefficients better than 0.998. Repeatability of the sample pretreatment procedure was calculated for six independent electrodialysis runs of artificial and real samples and was better than 11.8%. Recovery values between 96.3 and 110% were achieved for optimized electrodialysis conditions of standard solutions and real samples; lifetime of the dialysis membranes for pretreatment of real samples was estimated to 100 runs.

Vitamin E-coated cellulose acetate dialysis membrane: long-term effect on inflammation and oxidative stress

Background: Chronic inflammation and oxidative stress are prevalent in hemodialysis (HD) patients. We evaluated the long-term effect of a vitamin E-coated cellulose acetate (CAE) membrane on oxidative stress and inflammation. Methods: Nine patients were switched to CAE membrane for 3 months and then changed back to polysulfone (PS) membrane again for 6 months. Reactive oxygen metabolites and derivatives (d-ROMs), total antioxidant capacity (TAC) and superoxide dismutase (SOD) (oxidative stress biomarkers), high-sensitivity C-reactive protein (Hs-CRP), and interleukin-6 (IL-6) (inflammation biomarkers) were measured. Results: d-ROMs decreased and TAC rose significantly at the end of the study, whereas SOD increased rapidly and immediately after the end of CAE treatment. Hs-CRP and IL-6 levels were significantly lowered at the end of the study. Conclusions: Vitamin E supplementation by vitamin E-coated CAE dialysis membrane suppresses oxidative stress and inflammation.

Asymmetric cellulose acetate dialysis membranes: Synthesis, characterization, and performance

AbstractCellulose acetate (CA) is highly comparable to other synthetic polymer materials and is effective in the hemodialysis process. In this work, asymmetric CA membranes were synthesized with the phase‐inversion method. CA with a molecular weight of 52,000, poly(ethylene glycol) (PEG) with a molecular weight of 400, and 1‐methyl‐2‐pyrrolidone (NMP) were used as the polymer, additive, and solvent, respectively. The effects of the CA and PEG concentrations and coagulation bath temperature (CBT) on the morphology, pure water permeability (PWP), insulin/human serum albumin (HSA) transmission, and finally thermal and chemical stability of the prepared membranes were determined and investigated. In general, increasing the PEG concentration and CBT and reducing the CA concentration resulted in increased PWP and insulin/HSA transmission. Also, these variations facilitated the formation of macrovoids in the membrane sublayer. On the other hand, increasing the PEG and CA concentrations and reducing CBT resulted in increased thermal and chemical stability of the prepared membranes. Also, ratios of 15.5/10/74.5 and 17.5/10/72.5 (w/w) for the CA/PEG/NMP casting solutions and their immersion into coagulation baths with CBTs of 0 and 25°C, respectively, resulted in the preparation of membranes that had not only optimum sieving properties and higher PWP but also thermal and chemical stability better than that of conventional CA hemodialysis membranes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Lymphopenia in dialysis patients: a preliminary study indicating a possible role of apoptosis.

Lymphopenia is a common finding in dialysis patients. Since infection rate and mortality associated with infection are high in dialysis patients, lymphopenia may be one of the contributing factors. In the present study, we evaluated the mechanism responsible for lymphopenia in these patients. Lymphocytes isolated from dialysis patients showed increased apoptosis (p < 0.001) when compared to lymphocytes isolated from healthy subjects (healthy subjects, 0.5 +/- 0.2% vs. dialysis patients, 8.8 +/- 0.7% apoptotic cells/field). Sera from dialysis patients promoted lymphocyte apoptosis in a time- and dose-dependent manner. These sera also enhanced lymphocyte DNA fragmentation into multiple integers of 180 base pairs in the form of a ladder pattern. Cellulose acetate membranes promoted T cell apoptosis when compared to polysulfone membranes and to control. Cellulose acetate dialysis membranes also appear to promote lymphocyte FasL expression. Similarly, dialysis sera enhanced T cell Fas as well as FasL expression. Neither the cellulose acetate nor polysulfone membranes could induce FasL expression on B cells. Similarly, dialysis sera failed to induce FasL expression on B cells. On the other hand, anti-FasL antibodies attenuated dialysis sera-induced apoptosis in T as well as B cells. Interestingly, dialysis serum showed a 5-fold increase in FasL content when compared with control serum. These results suggest that dialysis-associated factors can induce autocrine death in T cells but the help of activated T cells is required to induce death in B cells.

Aged dialyzers and vision loss.

JAMA Acute Onset of Decreased Vision and Hearing Traced to Hemodialysis Treatment With Aged Dialyzers Joseph C. Hutter, PhD; Matthew J. Kuehnert, MD; Roland R. Wallis, PhD; Anne D. Lucas, PhD; Sumit Sen, PhD; William R. Jarvis, MD Context A recent event in which 7 patients at 1 hospital developed decreased vision and hearing, conjunctivitis, headache, and other severe neurologic symptoms 7 to 24 hours after hemodialysis drew attention to the issue of the long-term integrity of dialysis machines and materials. Objective To determine the cause of the adverse reactions that occurred during this event. Design, Patients, and Setting Retrospective cohort study of all 9 patients who received hemodialysis at hospital A on September 18, 1996, the day of the outbreak. A case-patient was defined as any hospital A patient with acute onset of decreased vision and hearing and conjunctivitis after dialysis on that day. Non–case-patients were all others who underwent dialysis on that day but did not develop adverse reactions. In an attempt to reproduce the conditions of the vent, cellulose acetate dialysis membranes of various ages were retrieved from other sources and tested for physical and chemical degradation, and degradation products were identified, characterized, and injected intravenously into rabbits. Main Outcome Measures Clinical signs and symptoms, time to resolution of symptoms, mortality, and dialyzer type and age, for case vs non–case-patients. Results Seven of the 9 patients met the case definition. In addition to diminished vision and hearing, conjunctivitis, and headache, some case-patients had blood leak alarm activation (n = 6), confusion/lethargy (n = 5), corneal opacification (n = 4), cardiac arrest (n = 2), or other neurologic signs and symptoms. One case-patient died during hospitalization after the event; 5 of 7 case-patients died within 13 months. Resolution of signs and symptoms varied but persisted more than 3 years or until death in 3 of the 6 patients who survived hospitalization. All case-patients but no non–case-patients were exposed to 11.5-year-old cellulose acetate dialyzers (all of these dialyzers were discarded by the hospital before our investigation). Laboratory investigation of field-retrieved 0- to 13.6-year-old dialyzers of similar type indicated significant chemical degradation in the older membranes. In vivo injection of extracts of membrane degradation products produced iritis and hemorrhages in rabbits' eyes. Conclusions Severe patient injury was associated with exposure to aged cellulose acetate membranes of dialyzers, allowing cellulose acetate degradation products to enter the blood. Clinicians should be aware that aged cellulose acetate membranes may cause severe adverse reactions. JAMA. 2000;283:2128-2134.

Acute onset of decreased vision and hearing traced to hemodialysis treatment with aged dialyzers.

A recent event in which 7 patients at 1 hospital developed decreased vision and hearing, conjunctivitis, headache, and other severe neurologic symptoms 7 to 24 hours after hemodialysis drew attention to the issue of the long-term integrity of dialysis machines and materials. To determine the cause of the adverse reactions that occurred during this event. Retrospective cohort study of all 9 patients who received hemodialysis at hospital A on September 18, 1996, the day of the outbreak. A case-patient was defined as any hospital A patient with acute onset of decreased vision and hearing and conjunctivitis after dialysis on that day. Non-case-patients were all others who underwent dialysis at hospital A on that day but did not develop adverse reactions. In an attempt to reproduce the conditions of the event, cellulose acetate dialysis membranes of various ages were retrieved from other sources and tested for physical and chemical degradation, and degradation products were identified, characterized, and injected intravenously into rabbits. Clinical signs and symptoms, time to resolution of symptoms, mortality, and dialyzer type and age, for case- vs non-case-patients. Seven of the 9 patients met the case definition. In addition to diminished vision and hearing, conjunctivitis, and headache, some case-patients had blood leak alarm activation (n=6), confusion/lethargy (n=5), corneal opacification (n=4), cardiac arrest (n=2), or other neurologic signs and symptoms. One case-patient died during hospitalization after the event; 5 of 7 case-patients died within 13 months. Resolution of signs and symptoms varied but persisted more than 3 years or until death in 3 of the 6 patients who survived hospitalization. All case-patients but no non-case-patients were exposed to 11.5-year-old cellulose acetate dialyzers (all of these dialyzers were discarded by the hospital before our investigation). Laboratory investigation of field-retrieved 0- to 13.6-year-old dialyzers of similar type indicated significant chemical degradation in the older membranes. In vivo injection of extracts of membrane degradation products produced iritis and hemorrhages in rabbits' eyes. Severe patient injury was associated with exposure to aged cellulose acetate membranes of dialyzers, allowing cellulose acetate degradation products to enter the blood. Clinicians should be aware that aged cellulose acetate membranes may cause severe adverse reactions.

Amperometric Determination of Lactic Acid. Applications on Milk Samples

Abstract A hydrogen peroxide electrochemical sensor, coupled with immobilized lactate oxidase and covered with a cellulose acetate dialysis membrane has been applied in flow analysis of lactate in milk samples. The hydrogen peroxide produced by the enzymatic reaction is measured with a platinum electrode polarized at +650 mV versus Ag/AgCl. Milk samples were analyzed and compared with a spectophotometric reference method. The developed procedure is very simple and the short response time allows its use in assaying milk samples on dairy farms.

Lactose Determination in Raw Milk with a Two-Enzyme Based Electrochemical Sensor

Abstract A hydrogen peroxide electrochemical sensor, coupled with two enzymes (s -galactosidase and glucose oxidase) immobilized on the surface of the sensor covered with a cellulose acetate dialysis membrane (cut off 100), is proposed for the analysis of lactose in raw milk. The resulting hydrogen peroxide formation is measured with a platinum electrode polarized at +650 mV versus Ag/AgCl. The procedure developed is very simple and the short response time permits its use in assaying milk samples on dairy farms.

Platelet adhesion and contact activation time tests on HEMA coated cellulose acetate membranes.

Surface modification of cellulose acetate dialysis membranes was carried out by 60Co radiation induced graft copolymerization of the hydrogel, hydroxyethyl methacrylate (HEMA). The degree of grafting was controlled by varying the HEMA monomer concentration in the grafting solution and the radiation dose. A continuous flow platelet adhesion test was designed which allows testing under conditions more closely approximating hemodialysis than other small scale in vitro tests. Platelet adhesion on treated membranes fell substantially with increasing surface HEMA concentration. The presence of HEMA on the membrane surface did not affect the membrane activated clotting times significantly.

Use of solubility parameters for the preparation of hemodialysis membrances

AbstractThe Solvent mixtures of acetone and ethanol (swelling agent) were selected for the preparation of cellulose acetate dialysis membranes using the solubility parameter concept. Increased concentration of ethanol or decreased concentration of cellulose acetate in the formulation resulted in membranes with higher dialysis rate constants but with decreased tensile strengths. The membranes prepared from 20 g of cellulose acetate per 100 ml of mixed solvent of 59.9 mole‐% acetone and 40.1 mole‐% ethanol were comparable to Cuprophane membrane but were better than those prepared by using formamide as a swelling agent.

Permeabilities of coagulated cellulose acetate dialysis membranes

AbstractThe diffusive flux of NaCl and the hydraulic flux of pure water through coagulated cellulose acetate membranes are examined. Coagulated cellulose acetate membranes (without densification by heat treatment or drying) possess higher permeability than what may be expected from the permeabilities of the dry polymer. Their overall hydraulic permeability (ultrafiltration rate of water) is greatly dependent upon the membrane casting conditions and the resulting asymmetry of the membrane. On the other hand, the asymmetry of a membrane does not play as great a role in the diffusive permeability of a solute. With homogeneous membranes, higher diffusive flux is always accompanied by higher hydraulic permeability. With asymmetric membranes, this is not always true. The diffusive permeability of NaCl and the hydraulic permeability of water through coagulated cellulose acetate membranes can be controlled nearly independently. Consequently, high diffusive (NaCl) permeability with low hydraulic water permeability and vice versa can be obtained by varying the casting conditions and also by partially saponifying the denser portion of the membrane.