Influence of surface modification and static pressure on microdialysis protein extraction efficiency
There is growing interest in using microdialysis (MD) for monitoring larger and more complex molecules such as neuropeptides and proteins. This promotes the use of MD membranes with molecular weight cut off (MWCO) of 100 kDa or above. The hydrodynamic property of the membrane 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 still lead to unstable catheter performance. The objective is to study in vitro how 500 kDa dextran and 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 spinal fluid, comparing native and Poloxamer 407 modified MD catheters. The collected dialysate fractions were examined for FR and protein EE, employing Dot-it Spot-it Protein Assay for total protein EE and targeted mass spectrometry (MS) for EE of individual proteins and peptides. The FR results suggested that the surface modified catheters were less sensitive to the pressure and provide higher precision, and provided a FR closer to 100 %. The surface modification did not show a significant effect on the protein EE. The average total protein EE of surface modified catheters was slightly higher than that of the native ones. The MS EE data of individual proteins showed a clear trend of complex response in EE with pressure.
KeywordsMicrodialysis Surface modification Poloxamer Protein Extraction efficiency
This research was in part supported by the Uppsala Berzelii Technology Centre for Neurodiagnostics, funded by the Swedish Governmental Agency for Innovation Systems and the Swedish Research Council Grant number P29797-1. Financial support from Åke Wiberg and Magnus Bergvall foundation (SBL) are also acknowledged. We acknowledge mDialysis and Pharmacosomos AS for sharing their knowledge and for material support and Visualize your Science for graphical assistance. This work was supported by the Science for Life Laboratory Mass Spectrometry Based Proteomics Facility in Uppsala. Data storage was obtained and supported by BILS (Bioinformatics Infrastructure for Life Sciences).
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