alexa Positively Charged Polyethersulfone Membranes: The Influence of Furosemide on the Zeta Potential | OMICS International
ISSN: 2155-9589
Journal of Membrane Science & Technology

Like us on:

Make the best use of Scientific Research and information from our 700+ peer reviewed, Open Access Journals that operates with the help of 50,000+ Editorial Board Members and esteemed reviewers and 1000+ Scientific associations in Medical, Clinical, Pharmaceutical, Engineering, Technology and Management Fields.
Meet Inspiring Speakers and Experts at our 3000+ Global Conferenceseries Events with over 600+ Conferences, 1200+ Symposiums and 1200+ Workshops on
Medical, Pharma, Engineering, Science, Technology and Business

Positively Charged Polyethersulfone Membranes: The Influence of Furosemide on the Zeta Potential

Joanna Gasch1, Claudia S Leopold2* and Holger Knoth1

1Hospital Pharmacy, University Hospital Carl Gustav Carus, Technical University of Dresden, Germany

2Department of Chemistry, Pharmaceutical Technology, University of Hamburg, Germany

*Corresponding Author:
Claudia S Leopold
Department of Chemistry
Pharmaceutical Technology
University of Hamburg
Hamburg, Germany
Tel: +49 (0)40 42838-3479
Fax: +49 (0)40 42838-6519
E-mail: [email protected]

Received date February 15, 2013; Accepted date March 18, 2013; Published date March 21, 2013

Citation: Gasch J, Leopold CS, Knoth H (2013) Positively Charged Polyethersulfone Membranes: The Influence of Furosemide on the Zeta Potential. J Membra Sci Technol 3:121. doi:10.4172/2155-9589.1000121

Copyright: © 2013 Gasch J, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Visit for more related articles at Journal of Membrane Science & Technology

Abstract

The aim of the present work is to measure changes in the Zeta potential of uncharged (PES0) and positively charged (PES+) polyethersulfone membranes, and to investigate their chemical composition. Endotoxin-retentive filters with a 0.2 μm PES0 and PES+ membranes are used for filtration of a furosemide sodium solution, with an increasing concentration up to 60 μmol/l. To analyze the chemical composition of both membranes, X-Ray photoelectron spectroscopy (XPS) was used. The Zeta potential was determined by a streaming current electrokinetic analyzer. The positive charge of the PES+ membrane corresponding to a positive Zeta potential decreased with increasing furosemide sodium concentration. In contrast, the Zeta potential of PES0 membranes hardly changes with increasing drug concentration. XPS allows the determination of the chemical composition of the investigated membranes. Both membranes only contain oxygen, carbon, sulfur and nitrogen. On the surface of the PES+ membrane, the positive charge is caused by ammonium nitrogen. No ionic additives could be detected. The manufacturer’s intended period of PES+ filter use (96 h), should only be applied to nonionic infusion solutions. Hence, information should be given on the maximum period of filter use, if ionic infusion solutions are applied.

Keywords

Polyethersulfone; Inline filter; Ionic interaction; Drug retention

Introduction

Infusion filters are of outstanding importance for the safety in intravenous drug therapy. They are commonly used as inline filters to minimize particle and microbiological burden, to reduce the incidence of phlebitis and sepsis associated with intravenous infusions [1-7]. Most of the membranes used in intensive care units are made of polyamide 6.6 or polyethersulfone. Materials such as cellulose and polycarbonate are not longer in use as membranes in inline filters, but they still can be found in the preparation of pharmaceutical solutions [8]. Polyethersulfone can be modified with different agents, to achieve different membrane properties [5,9]. For inline filtration, polyethersulfone is available in a positively and an uncharged form.

The measurement of the streaming potential is one of the numerous methods in membrane characterization. The streaming potential is an electokinetic effect, which occurs when a mobile charged phase– electrolyte solution–moves with respect to a solid charged membrane. The Zeta potential is related to the electrokinetic potential created at the boundary between the mobile and the solid phase. The Zeta potential depends on the pH and the electrolyte concentration of the feeding solution [10,11]. The membranes may develop a positive or negative Zeta potential, as a result of the interaction with functional groups present on the membrane surface. This aspect is systematically used to develop membranes for specific tasks in separation [12], and to demonstrate the importance of ions on protein transport through semipermeable membranes [11].

The electrokinetic double layer arises on the membrane surface, consisting of the inner Helmholtz layer and the outer Helmholtz layer, also known as Stern layer. The Stern layer is the first adsorbed ion layer, next to the membrane. The extent of ion adsorption is determined by electrical and other interactions between ions in the feeding solution, and the membrane surface. The ions outside the Stern layer form a diffuse layer. At the shear layer, which depends on the movement in the system, the Zeta potential may be measured. Its value is used to characterize the electrical properties of the membrane surface. A continuous measurement of the Zeta potential allows determining qualitative and quantitative changes at the membrane surface.

The aim of the present work is to analyze the changes in the Zeta potential of uncharged (PES0) and positively charged (PES+) polyethersulfone membranes, resulting from undesired furosemide sodium retention [13]. In the literature, numerous studies on the interactions between different drugs or pharmaceutical additives and filter materials, and/or syringe and tube materials can be found [14-25].

To analyze the chemical composition of the PES0 and PES+ membranes, X-Ray photoelectron spectroscopy (XPS) was used. XPS is a method, also known as electron spectroscopy for chemical analysis (ESCA). The membrane is irradiated with X-Rays, and photoelectrons are emitted from the surface. The kinetic energy of the emitted electrons is characteristic for the element to which the photoelectrons belong. The results of these experiments are required to gain information on the source of the positive charges at the PES+ membrane surface.

Materials

Commercial drug solutions

Lasix® 20 mg solution for injection (Sanofi-Aventis, Frankfurt am Main, Germany): 1 ampoule containing 2 ml solution for injection with 21.3 mg furosemide sodium (corresponding to 20 mg furosemide); additives: sodium chloride, sodium hydroxide, water for injection. To measure the effect of furosemide sodium on the Zeta potential of the membrane, Furosemide was diluted to a concentration of 60 μmol/L.

Eluents

Ultrapure water was prepared with an Ultrapure Water Purification System (Super-AQUADEM®, Wilhelm Werner GmbH, Leverkusen, Germany). Potassium chloride (analytical grade) and CertiPur® buffer solution pH 4/7/10 for calibration (all from Merck, Darmstadt, Germany), were used.

Filters

Intrapur® Paed (BBraun, Melsungen, Germany) is an endotoxinretentive filter with a 0.2 μm Supor® (positively charged polyethersulfone, PES+) membrane and position-independent air removal. Filling volume is 1 ml; the maximum working pressure is 3 bars. Sterifix® Paed (BBraun, Melsungen, Germany) is equivalent to Intrapur® Paed. However, it contains an uncharged 0.2 μm polyethersulfone membrane filter (PES0).

Methods

Streaming potential measurements

The Zeta potential of isolated PES0 and PES+ filter membranes was determined by a streaming current electrokinetic analyzer (SurPass®, Anton Paar, Graz, Austria), equipped with a conductivity electrode (Schott® LF 5100, SI Analytics, Mainz, Germany) and a pH electrode (Schott® N 61, SI Analytics, Mainz, Germany). VisioLab® for electrokinetic analyzer (EKA) V1.03 was used for data acquisition. To minimize the background noise, 0.001% NaCl aqueous solution was taken.

To determine the Zeta potential over a period of 10 h, measurements were done every 30 min, during the first nine hours. After 24 h, one final measurement was done. During the same time interval of 30 min, conductivity of the samples and their pH values were measured. The pH value (5.07-6.54) remained constant during the time course of the experiment. All measurements were done in triplicate.

Surface characterization

The chemical characterization of the surface of both PES0 and PES+ membranes was done by X-ray photoelectron spectroscopy (XPS, Axis® 165, Kratos Analytical, Manchester, Great Britain), with an Al Kα radiation as the excitation source. The spectra were recorded at a variable angle in the constant pass energy mode at 80 eV and 20 Ev, using an analysis area of 300 μm×700 μm, and a depth of 7 nm. The spectra were evaluated regarding to the C, N, O, and S peaks.

Results

Zeta potential measurements

To detect changes in the Zeta potential over the time course of the experiment, temperature (Figures 1 and 2) and conductivity (Figure 3) were measured in a 0.001% aqueous NaCl solution. The measurements with PES+ were done on the apical side of the membrane, which is the side of the influx of the infusion solution, and the basolateral side, which is the side of the efflux of the infusion solution. Both sides seem to be different in their structure [13]. With PES0, the experiments were only done on the apical side, as in the SEM pictures taken; no difference between the influx side and efflux side of the PES0 membranes could be observed [13].

membrane-science-technology-Zeta-potential-temperature-changes

Figure 1: Zeta potential and temperature changes of PES+ membrane over a time period of 10 h (means, n=3). A: ____ Zeta potential of PES+ apical side, ••• Zeta potential of PES+ basolateral side B: ____ temperature of PES+ apical side, ••• temperature of PES+ basolateral side.

membrane-science-technology-Zeta-potential

Figure 2: Zeta potential and temperature changes of PES° membrane over a time period of 10 h (means, n=3). A: Zeta potential of PES° apical side; B temperature of PES° apical side.

membrane-science-technology-basolateral-side

Figure 3: Conductivity changes of PES0 and PES+ membranes in 0.001% NaCl over a period of 10 h (means, n=3): ____ conductivity of PES+ apical side, ···· conductivity of PES+ basolateral side, - - - conductivity of PES0 apical side.

As shown in figures 1-3, all measured data is almost constant during the time course of the experiment.

With increasing furosemide sodium concentration in the feeding solution, the Zeta potential of the PES+ membrane changes from positive to negative values (Figure 4). In contrast, with the PES0 membrane, there are no remarkable changes of the Zeta potential.

membrane-science-technology-furosemide-concentration-period

Figure 4: Zeta potential changes of PES0 and PES+ membranes in dependence of the furosemide concentration over a period of 10 h (means, n=3): ____ Zeta potential of PES+ apical side, •••• Zeta potential of PES+ basolateral side, - - - Zeta potential of PES0 apical side.

To determine the furosemide sodium concentration in the measuring chamber during the time period of the experiment, conductivity was measured (Figure 5).

membrane-science-technology-Conductivity-changes

Figure 5: Conductivity changes of PES0 and PES+ membranes in dependence of the furosemide concentration over a period of 10 h (means, n=3): ____ conductivity of PES+ apical side, •••• conductivity of PES+ basolateral side, - - - conductivity of PES0 apical side.

Surface analysis (XPS)

The surface of PES0 and PES+ membranes consist basically of carbon and oxygen, with small amounts of nitrogen and sulfur (Table 1). In the PES0 membrane, the nitrogen content was found to be higher than in the PES+ membrane.

Element PES0[%] PES+[%]
N 3.5 <0.5
O 15.7 21.9
C 77.2 74.5
S 3.7 3.6

Table 1: Qualitative and quantitative composition of PES0 and PES+ membranes at a depth of 7 nm [8].

In figure 6, the XPS spectra of both membranes are displayed. The similarity is noticeable. It is obvious that both membranes have PES as the basic structure.

membrane-science-technology-XPS-spectra-PES

Figure 6: XPS spectra of PES+ (A) and PES0 (B) membranes.

In contrast to PES+, with PES0 a clear N1s-peak can be detected (Figure 7). From its binding energy (399.32 eV), an amine or amide nitrogen is expected. PES+ membranes show two structures: one with lower binding energy (398.92 eV) and another, which is positively charged ammonium nitrogen (401.85 eV).

membrane-science-technology-PES-membranes

Figure 7: N1s peaks of ____ PES0 and ••• PES+ membranes.

For both membranes, the O1s spectra are obviously different (Figure 8). In the PES+ membrane, the spectrum is characterized by three peaks (530.58 eV (weak), 531.

membrane-science-technology-O-peaks

Figure 8: O1s peaks of ____ PES+ and •••• PES0 membranes.

The C1s spectra of the PES+ and PES0 membranes also show differences (Figure 9).

membrane-science-technology-C1-peaks-PES

Figure 9: C1s peaks of ____ PES+ and •••• PES0 membranes.

Discussion

The positive charge of the PES+ membrane, and the resulting positive Zeta potential, decreases with increasing furosemide sodium concentration. It even approximates the negative Zeta potential of the PES0 membrane. The membrane charge depends on its chemical structure. Unfortunately, most manufacturers do not give information on the cause of the positive charge. Because of this lack of information, inconsistent data is found in the literature. Even in the present study, a PES0 membrane declared as uncharged by the manufacture showed a negative Zeta potential. Usually, end-users do not have information on the exact composition of commercially available membranes [15].

With XPS, it could be shown that both membranes only contain oxygen, carbon, sulfur and nitrogen. The polymer matrix has two characteristic functional groups: the hydrophilic sulfonyl group, which can participate in hydrogen bonding, and the hydrophobic benzene, which interacts in the form of van der Waals forces. In the matrix itself, oxygen is likely to be the most reactive atom. In none of the membranes, ionic additives such as electrolytes could be detected. As a result of the surface analysis, the peaks of interest appear in the photoelectron spectrum at a kinetic energy, which indicates two different functional groups containing nitrogen. In combination with the binding energy of the oxygen, an amide structure in the PES0 membrane, and an ammonium structure in the PES+ membrane, is most likely.

Conclusion

In 1997, the BBraun Company conducted a research study on endotoxin-retaining PES+ membranes [26]. In this investigation, water for injection containing 5.63 EU/ml endotoxin was filtered with a 0.2 μm PES+ membrane. This membrane retained the endotoxin effectively. However, in these experiments, an ion-free aqueous endotoxin solution was used as test solution. In the daily routine, most of the infusibile drugs are administered in ionic solutions such as NaCl or Ringer solution. It is unusual to use water for injection as diluent for infusion stock solutions. Because of the ion-free test solution in the BBraun experiment, the Zeta potential hardly changes, and negatively charged endotoxins can be captured by the membrane with the positive Zeta potential. This experimental setup does not reflect the situation in the daily routine. Hence, conclusions for intravenous drug application in neonatology, where the drug concentrations and the infusion rates are very low, cannot be drawn. As a result, it has to be questioned, to what extent positively charged filter membranes do really have an advantage over “uncharged” membranes.

References

Select your language of interest to view the total content in your interested language
Post your comment

Share This Article

Relevant Topics

Recommended Conferences

  • 8th World Congress on Biopolymers June 28-30, 2018 Berlin, Germany.
    November 19-21-2018 Dubai, Romania
  • 3rd International Conference on Molecular Biology & Nucleic Acids August 27-28, 2018 Toronto, Ontario, Canada.
    August 27-28, 2018 Toronto, Canada
  • 5th International Conference on Glycobiology, Lipids & Proteomics August 27-28, 2018 Toronto, Ontario, Canada.
    August 27-28, 2018 Toronto, Canada
  • International Conference on Computational Biology and Bioinformatics Sep 05-06 2018 Tokyo, Japan.
    Sep 05-06 2018 Tokyo, Japan
  • International Conference on Nutritional Biochemistry September 10-11, 2018 Prague, Czech Republic.
    September 10-11, 2018 Prague, Czech Republic
  • 4th International Conference on Enzymology and Lipid Science September 17-18, 2018 Singapore.
    September 17-18, 2018 Singapore City, Singapore
  • 4th Glycobiology World Congress September 17-19, 2018 Rome, Italy.
    September 17-19, 2018 Rome, Italy
  • 12thInternational Conference on Advancements in Bioinformatics and Drug Discovery November 26-27, 2018 Dublin, Ireland.
    November 26-27, 2018 Dublin, Ireland
  • 4th International Conference on Genetic and Protein Engineering December 05-06, 2018 Chicago, USA
    ,

Article Usage

  • Total views: 13059
  • [From(publication date):
    June-2013 - Jun 23, 2018]
  • Breakdown by view type
  • HTML page views : 9240
  • PDF downloads : 3819
 

Post your comment

captcha   Reload  Can't read the image? click here to refresh

Peer Reviewed Journals
 
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals
International Conferences 2018-19
 
Meet Inspiring Speakers and Experts at our 3000+ Global Annual Meetings

Contact Us

Agri & Aquaculture Journals

Dr. Krish

[email protected]

+1-702-714-7001Extn: 9040

Biochemistry Journals

Datta A

[email protected]

1-702-714-7001Extn: 9037

Business & Management Journals

Ronald

[email protected]

1-702-714-7001Extn: 9042

Chemistry Journals

Gabriel Shaw

[email protected]

1-702-714-7001Extn: 9040

Clinical Journals

Datta A

[email protected]

1-702-714-7001Extn: 9037

Engineering Journals

James Franklin

[email protected]

1-702-714-7001Extn: 9042

Food & Nutrition Journals

Katie Wilson

[email protected]

1-702-714-7001Extn: 9042

General Science

Andrea Jason

[email protected]

1-702-714-7001Extn: 9043

Genetics & Molecular Biology Journals

Anna Melissa

[email protected]

1-702-714-7001Extn: 9006

Immunology & Microbiology Journals

David Gorantl

[email protected]

1-702-714-7001Extn: 9014

Materials Science Journals

Rachle Green

[email protected]

1-702-714-7001Extn: 9039

Nursing & Health Care Journals

Stephanie Skinner

[email protected]

1-702-714-7001Extn: 9039

Medical Journals

Nimmi Anna

[email protected]

1-702-714-7001Extn: 9038

Neuroscience & Psychology Journals

Nathan T

[email protected]

1-702-714-7001Extn: 9041

Pharmaceutical Sciences Journals

Ann Jose

[email protected]

1-702-714-7001Extn: 9007

Social & Political Science Journals

Steve Harry

[email protected]

1-702-714-7001Extn: 9042

 
© 2008- 2018 OMICS International - Open Access Publisher. Best viewed in Mozilla Firefox | Google Chrome | Above IE 7.0 version
Leave Your Message 24x7