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Electrosteric Stabilization and Its Role on Cooperative Magnetophoresis of Colloidal Magnetic Nanoparticles.
MedLine Citation:
PMID:  23025323     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
A detailed study on the conflicting role of colloid stability plays in magnetophoresis is presented. Magnetic iron oxide particles (MIOPs) which were sterically stabilized via surface modificaiton with poly(sodium 4-styrene sulfonate) of different molecular weight (ie. 70 kDa and 1000 kDa) were employed as our model system. Both sedimentation kinetics and quartz crystal microbalance with dissipation (QCM-D) measurements suggested that PSS 70 kDa is a better stabilizer as compared to PSS 1000kDa. This observation is mostly attributed to the bridging flocculation of PSS 1000kDa decorated MIOPs originated from the extended polymeric conformation layer. Later on, a lab-scale High Gradient Magnetic Separation (HGMS) device was designed to study the magnetophoretic collection of MIOPs. Our experimental results revealed that the more colloidally stable the MIOP suspension is, the harder it is to be magnetically isolated by HGMS. At 50 mg/L, naked MIOPs without coating can be easily captured by HGMS at separation efficiency up to 96.9 ± 2.6 %. However, the degree of separation dropped quite drastically to 83.1 ± 1.2 % and 67.7 ± 4.6 %., for MIOPs with PSS 1000k- and PSS 70k coating, respectively. This observation clearly implies that polyelectrolyte coating which usually employed to electrosterically stabilize a colloidal system, is in turn compromises the magnetic isolation efficiency. By artificially destroy the colloidal stability of the MIOPs by ionic strength increment, the ability for HGMS to recover the most stable suspension (ie. PSS 70K-coated MIOPs) increased to > 86 % at 100 mM monovalent ion (Na+) or at 10 mM divalent ion (Ca2+). This in turn, has verified the conflicting role of colloidal stability on magnetophoretic separation.
Authors:
Swee Pin Yeap; Abdul Latif Ahmad; Boon Seng Ooi; Jitkang Lim
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-1
Journal Detail:
Title:  Langmuir : the ACS journal of surfaces and colloids     Volume:  -     ISSN:  1520-5827     ISO Abbreviation:  Langmuir     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-2     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9882736     Medline TA:  Langmuir     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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