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Chu, Jiangtao
Publications (10 of 13) Show all publications
Chu, J., Undin, T., Lind, S., Dahlin, A. & Hjort, K. (2015). Influence of different pluronic surface modifications and pressure on microdialysis protein extraction efficiency. Biomedical microdevices (Print).
Open this publication in new window or tab >>Influence of different pluronic surface modifications and pressure on microdialysis protein extraction efficiency
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2015 (English)In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781Article in journal (Refereed) Submitted
Abstract [en]

There is growing interest in using microdialysis (MD) for monitoring larger and more complexmolecules such as neuropeptides and proteins. This promotes the use of MD membranes withmolecular weight cut off (MWCO) of 100 kDa. Hence, the hydrodynamic property of themembrane goes to ultrafiltration, making the sampling more sensitive to pressure changes. Also,despite the large membrane pore size, studies have shown that membrane biofouling still leads tounstable catheter performance. Our objective is to study in vitro how four kinds of surfacemodifications (Pluronic L31, L44, F87 and F127+L31) affect the fluid recovery (FR) andextraction efficiency (EE) of 100 kDa MWCO MD catheters, under controlled pressure. Apressure chamber was employed to facilitate the tests, using as MD sample a protein standardwith proteins of similar concentrations as in human cerebral spinal fluid. The collected dialysatefractions were examined for FR and EE. Targeted mass spectrometry analysed the EE ofindividual proteins and peptides. The thicker the pluronic adsorption layer, the less thehydrodynamic diameter of the membrane pores, leading to lower and more stable FR. The foursurface modifications had three different behaviours: Pluronic F127 + L31 showed similarbehavior to the Pluronic F127 and the native original membrane; Pluronic F87 showed acontinuous EE increase with pressure; Pluronic L31 and L44 showed similar EE values, whichwere stable with pressure. Different surface modifications are clearly selective to differentproteins and peptides. We conclude that a pluronic surface modification could provide MDsampling with more stable FR, and more stable or enhanced EE with high FR, depending on theobjective of the sampling.

Place, publisher, year, edition, pages
Springer: , 2015
Keyword
microdialysis, surface modification, poloxamer, protein, extraction efficiency
National Category
Nano Technology
Research subject
Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-261557 (URN)
Funder
Berzelii Centre EXSELENT
Available from: 2015-09-01 Created: 2015-09-01 Last updated: 2017-12-04Bibliographically approved
Chu, J. (2015). Influence of Surface Modification and Static Pressure on Microdialysis Protein Extraction Efficiency. In: 26th Micromechanics and Microsystems Europe Workshop: . Paper presented at 26th Micromechanics and Microsystems Europe Workshop (MME 2015, Sept. 20-23, 2015,Toledo, Spain) (pp. D8). .
Open this publication in new window or tab >>Influence of Surface Modification and Static Pressure on Microdialysis Protein Extraction Efficiency
2015 (English)In: 26th Micromechanics and Microsystems Europe Workshop, 2015, D8- p.Conference paper, Poster (with or without abstract) (Other academic)
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-284874 (URN)
Conference
26th Micromechanics and Microsystems Europe Workshop (MME 2015, Sept. 20-23, 2015,Toledo, Spain)
Available from: 2016-04-19 Created: 2016-04-19 Last updated: 2016-04-26
Chu, J., Undin, T., Bergström Lind, S., Hjort, K. & Dahlin, A. (2015). Influence of surface modification and static pressure on microdialysis protein extraction efficiency. Biomedical microdevices (Print), 17(5), Article ID UNSP 96.
Open this publication in new window or tab >>Influence of surface modification and static pressure on microdialysis protein extraction efficiency
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2015 (English)In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 17, no 5, UNSP 96Article in journal (Refereed) Published
Abstract [en]

There is growing interest in using microdialysis (MD) for monitoring larger and more complexmolecules such as neuropeptides and proteins. This promotes the use of MD membranes withmolecular weight cut off (MWCO) of 100 kDa or above. The hydrodynamic property of themembrane goes to ultrafiltration or beyond, making the MD catheters more sensitive to pressure.In the meantime, despite the large pore size, studies have shown that membrane biofouling stilllead to unstable catheter performance. The objective is to study in vitro how 500 kDa dextranand Poloxamer 407 surface modification affect the fluid recovery (FR) and extraction efficiency(EE) of 100 kDa MWCO MD catheters. A pressure chamber was designed to facilitate the tests,using as MD sample a protein standard with similar concentrations as in human cerebral spinalfluid, comparing native and Poloxamer 407 modified MD catheters. The collected dialysatefractions were examined for FR and protein EE, employing Dot-it Spot-it Protein Assay for totalprotein EE and targeted mass spectrometry (MS) for EE of individual proteins and peptides. TheFR results suggested that the surface modified catheters were less sensitive to the pressure andprovide higher precision, and provided a FR closer to 100%. The surface modification did notshow a significant effect on the protein EE. The average total protein EE of surface modifiedcatheters was slightly higher than that of the native ones. The MS EE data of individual proteinsshowed a clear trend of complex response in EE with pressure.

Place, publisher, year, edition, pages
Springer: , 2015
Keyword
microdialysis, surface modification, poloxamer, protein, extraction efficiency
National Category
Nano Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-261031 (URN)10.1007/s10544-015-0005-3 (DOI)000362281200013 ()26342494 (PubMedID)
Funder
Berzelii Centre EXSELENTSwedish Research Council, P29797-1Åke Wiberg FoundationMagnus Bergvall FoundationScience for Life Laboratory - a national resource center for high-throughput molecular bioscience
Available from: 2015-08-28 Created: 2015-08-28 Last updated: 2017-12-04Bibliographically approved
Chu, J. (2015). Microdialysis Sampling of Macro Molecules: Fluid Characteristics, Extraction Efficiency and Enhanced Performance. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis.
Open this publication in new window or tab >>Microdialysis Sampling of Macro Molecules: Fluid Characteristics, Extraction Efficiency and Enhanced Performance
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, fluid characteristics and sampling efficiency of high molecular weight cut-off microdialysis are presented, with the aim of improving the understanding of microdialysis sampling mechanisms and its performance regarding extraction efficiency of biological fluid and biomarkers.

Microdialysis is a well-established clinical sampling tool for monitoring small biomarkers such as lactate and glucose. In recent years, interest has raised in using high molecular weight cut-off microdialysis to sample macro molecules such as neuropeptides, cytokines and proteins. However, with the increase of the membrane pore size, high molecular weight cut-off microdialysis exhibits drawbacks such like unstable catheter performance, imbalanced fluid recovery, low and unstable molecule extraction efficiency, etc. But still, the fluid characteristics of high molecular weight cut-off microdialysis is rarely studied, and the clinical or in vitro molecule sampling efficiency from recent studies vary from each other and are difficult to compare.  

Therefore, in this thesis three aspects of high molecular weight cut-off microdialysis have been explored. The first, the fluid characteristics of large pore microdialysis has been investigated, theoretically and experimentally. The results suggest that the experimental fluid recovery is in consistency with its theoretical formula. The second, the macromolecule transport behaviour has been visualized and semi-quantified, using an in vitro test system and fluorescence imaging. The third, two in vitro tests have been done to mimic in vivo cerebrospinal fluid sampling under pressurization, using native and differently surface modified catheters. As results, individual protein/peptide extraction efficiencies were achieved, using targeted mass spectrometry analysis.

In summary, a theory system of the fluid characteristics of high molecular weight cut-off microdialysis has been built and testified; Macromolecular transport of microdialysis catheter has been visualized; In vivo biomolecules sampling has been simulated by well-defined in vitro studies; Individual biomolecular extraction efficiency has been shown; Different surface modifications of microdialysis catheter have been investigated. It was found that, improved sampling performance can be achieved, in terms of balanced fluid recovery and controlled protein extraction efficiency.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 52 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1278
Keyword
microdialysis, high molecular weight cut-off, fluid characteristics, fluid recovery, extraction efficiency, biomarker, microporous membrane, macromolecule transport, transmembrane, large pore, surface modification, pluronic, dextran, in vitro, microdialysis catheter
National Category
Manufacturing, Surface and Joining Technology Nano Technology
Research subject
Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-261068 (URN)978-91-554-9315-8 (ISBN)
Public defence
2015-10-16, Polhem Salen, Angstrom Laboratory, Uppsala, 09:15 (English)
Opponent
Supervisors
Funder
Berzelii Centre EXSELENT
Available from: 2015-09-25 Created: 2015-08-28 Last updated: 2015-10-01
Chu, J., Undin, T., Dahlin, A., Wang, C., Park, J. & Hjort, K. (2015). Protein Desalination Chip for Mass Spectrometry Sample Preparation. In: : . Paper presented at The 19th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2015. October 25-29, 2015. Gyeongju, Korea.. MicroTAS.
Open this publication in new window or tab >>Protein Desalination Chip for Mass Spectrometry Sample Preparation
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2015 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

This work focuses on desalination of a protein sample in a lab-on-chip device using the ion concentration polarization (ICP) technique. It was demonstrated with a salt containing buffer with four proteins and two peptides of concentrations typical to cerebrospinal fluid (CSF). Not only was the output desalinated but its protein concentration with large molecular weight (MW) was as much as 3 times higher for the largest protein compared to the original. We conclude that ICP based microfluidic chips have great potential for desalination and protein concentration in microdialysis sampling coupled to mass spectroscopy (MS).

Place, publisher, year, edition, pages
MicroTAS: , 2015
Keyword
Ion concentration polarization, Desalination, Protein, Mass spectroscopy
National Category
Nano Technology
Research subject
Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-261067 (URN)
Conference
The 19th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2015. October 25-29, 2015. Gyeongju, Korea.
Available from: 2015-08-28 Created: 2015-08-28 Last updated: 2016-01-05
Hillered, L., Dahlin, A. P., Clausen, F., Chu, J., Bergquist, J., Hjort, K., . . . Lewén, A. (2014). Cerebral microdialysis for protein biomarker monitoring in the neurointensive care setting - a technical approach. Frontiers in Neurology, 5, 245.
Open this publication in new window or tab >>Cerebral microdialysis for protein biomarker monitoring in the neurointensive care setting - a technical approach
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2014 (English)In: Frontiers in Neurology, ISSN 1664-2295, E-ISSN 1664-2295, Vol. 5, 245- p.Article in journal (Refereed) Published
Abstract [en]

Cerebral microdialysis (MD) was introduced as a neurochemical monitoring method in the early 1990s and is currently widely used for the sampling of low molecular weight molecules, signaling energy crisis, and cellular distress in the neurointensive care (NIC) setting. There is a growing interest in MD for harvesting of intracerebral protein biomarkers of secondary injury mechanisms in acute traumatic and neurovascular brain injury in the NIC community. The initial enthusiasm over the opportunity to sample protein biomarkers with high molecular weight cut-off MD catheters has dampened somewhat with the emerging realization of inherent methodological problems including protein-protein interaction, protein adhesion, and biofouling, causing an unstable in vivo performance (i.e., fluid recovery and extraction efficiency) of the MD catheter. This review will focus on the results of a multidisciplinary collaborative effort, within the Uppsala Berzelii Centre for Neurodiagnostics during the past several years, to study the features of the complex process of high molecular weight cut-off MD for protein biomarkers. This research has led to new methodology showing robust in vivo performance with optimized fluid recovery and improved extraction efficiency, allowing for more accurate biomarker monitoring. In combination with evolving analytical methodology allowing for multiplex biomarker analysis in ultra-small MD samples, a new opportunity opens up for high-resolution temporal mapping of secondary injury cascades, such as neuroinflammation and other cell injury reactions directly in the injured human brain. Such data may provide an important basis for improved characterization of complex injuries, e.g., traumatic and neurovascular brain injury, and help in defining targets and treatment windows for neuroprotective drug development.

National Category
Neurology Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-239227 (URN)10.3389/fneur.2014.00245 (DOI)25520696 (PubMedID)
Available from: 2014-12-19 Created: 2014-12-19 Last updated: 2017-12-05Bibliographically approved
Chu, J., Koudriavtsev, V., Hjort, K. & Dahlin, A. P. (2014). Flourescence imaging of molecule transport in high molecular weight cut-off microdialysis. In: : . Paper presented at 10th Micronano Systems Workshop (MSW 2014, 15-16 May, Uppsala, Sweden) (pp. 249-252). .
Open this publication in new window or tab >>Flourescence imaging of molecule transport in high molecular weight cut-off microdialysis
2014 (English)Conference paper, Poster (with or without abstract) (Refereed)
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:uu:diva-239237 (URN)
Conference
10th Micronano Systems Workshop (MSW 2014, 15-16 May, Uppsala, Sweden)
Available from: 2014-12-19 Created: 2014-12-19 Last updated: 2016-04-22
Chu, J., Koudriavtsev, V., Hjort, K. & Dahlin, A. P. (2014). Fluorescence imaging of macromolecule transport in high molecular weight cut-off microdialysis. Analytical and Bioanalytical Chemistry, 406(29), 7601-7609.
Open this publication in new window or tab >>Fluorescence imaging of macromolecule transport in high molecular weight cut-off microdialysis
2014 (English)In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 406, no 29, 7601-7609 p.Article in journal (Refereed) Published
Abstract [en]

When microdialysis (MD) membrane exceeds molecular weight cut-off (MWCO) of 100 kDa, the fluid mechanics are in the ultrafiltration regime. Consequently, fluidic mass transport of macromolecules in the perfusate over the membrane may reduce the biological relevance of the sampling and cause an inflammatory response in the test subject. Therefore, a method to investigate the molecular transport of high MWCO MD is presented. An in vitro test chamber was fabricated to facilitate the fluorescent imaging of the MD sampling process, using fluoresceinylisothiocyanate (FITC) dextran and fluorescence microscopy. Qualitative studies on dextran behavior inside and outside the membrane were performed. Semiquantitative results showed clear dextran leakage from both 40 and 250 kDa dextran when 100 kDa MWCO membranes were used. Dextran 40 kDa leaked out with an order of magnitude higher concentration and the leakage pattern resembled more of a convective flow pattern compared with dextran 250 kDa, where the leakage pattern was more diffusion based. No leakage was observed when dextran 500 kDa was used as a colloid osmotic agent. The results in this study suggest that fluorescence imaging could be used as a method for qualitative and semiquantitative molecular transport and fluid dynamics studies of MD membranes and other hollow fiber catheter membranes.

National Category
Other Medical Engineering Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-239233 (URN)10.1007/s00216-014-8192-y (DOI)000344860300019 ()25286875 (PubMedID)
Available from: 2014-12-19 Created: 2014-12-19 Last updated: 2017-12-05Bibliographically approved
Chu, J., Hjort, K., Larsson, A. & Dahlin, A. P. (2014). Impact of static pressure on transmembrane fluid exchange in high molecular weight cut off microdialysis. Biomedical microdevices (Print), 16(2), 301-310.
Open this publication in new window or tab >>Impact of static pressure on transmembrane fluid exchange in high molecular weight cut off microdialysis
2014 (English)In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 16, no 2, 301-310 p.Article in journal (Refereed) Published
Abstract [en]

With the interest of studying larger biomolecules by microdialysis (MD), this sampling technique has reached into the ultrafiltration region of fluid exchange, where fluid recovery (FR)  has a strong dependence on pressure. Hence in this study, we focus on the fluid exchange across the high molecular weight cut off MD membrane under the influence of the static pressure in the sampling environment. A theoretical model is presented for MD with such membranes, where FR has a linear dependence upon the static pressure of the sample. Transmembrane (TM) osmotic pressure difference and MD perfusion rate decide how fast FR increases with increased static pressure.

A test chamber for in vitro MD under static pressure was constructed and validated. It can hold four MD probes under controlled pressurized conditions. Comparison showed good agreement between experiment and theory. Moreover, test results showed that the fluid recovery of the test chamber MD can be set accurately via the chamber pressure, which is controlled by sample injection into the chamber at precise rate. This in vitro system is designed for modelling in vivo MD in cerebrospinal fluid and studies with biological samples in this system may be good models for in vivo MD. 

National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-212726 (URN)10.1007/s10544-013-9833-1 (DOI)000334362000013 ()
Funder
Swedish Research Council, P29797-1
Available from: 2013-12-13 Created: 2013-12-13 Last updated: 2017-12-06Bibliographically approved
Clausen, F., Dahlin, A., Chu, J., Kaller, B., During, E., Marklund, N. & Hillered, L. (2014). Novel Microdialysis Method to Study The Acute Cytokine Response to Diffuse Traumatic Brain Injury in the Rat. Paper presented at 11th Symposium of the International-Neurotrauma-Society, MAR 19-23, 2014, Budapest, HUNGARY. Journal of Neurotrauma, 31(5), A19-A19.
Open this publication in new window or tab >>Novel Microdialysis Method to Study The Acute Cytokine Response to Diffuse Traumatic Brain Injury in the Rat
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2014 (English)In: Journal of Neurotrauma, ISSN 0897-7151, E-ISSN 1557-9042, Vol. 31, no 5, A19-A19 p.Article in journal, Meeting abstract (Refereed) Published
National Category
Neurosciences Neurology Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-228365 (URN)000331799600063 ()
Conference
11th Symposium of the International-Neurotrauma-Society, MAR 19-23, 2014, Budapest, HUNGARY
Available from: 2014-07-14 Created: 2014-07-11 Last updated: 2018-01-11Bibliographically approved
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