title: The role of particle-to-cell interactions in dictating nanoparticle aided magnetophoretic separation of microalgal cells.
abstract: Successful application of a magnetophoretic separation technique for harvesting biological cells often relies on the need to tag the cells with magnetic nanoparticles. This study investigates the underlying principle behind the attachment of iron oxide nanoparticles (IONPs) onto microalgal cells, Chlorella sp. and Nannochloropsis sp., in both freshwater and seawater, by taking into account the contributions of various colloidal forces involved. The complex interplay between van der Waals (vdW), electrostatic (ES) and Lewis acid-base interactions (AB) in dictating IONP attachment was studied under the framework of extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) analysis. Our results showed that ES interaction plays an important role in determining the net interaction between the Chlorella sp. cells and IONPs in freshwater, while the AB and vdW interactions play a more dominant role in dictating the net particle-to-cell interaction in high ionic strength media (≥100 mM NaCl), such as seawater. XDLVO predicted effective attachment between cells and surface functionalized IONPs (SF-IONPs) with an estimated secondary minimum of -3.12 kT in freshwater. This prediction is in accordance with the experimental observation in which 98.89% of cells can be magnetophoretically separated from freshwater with SF-IONPs. We have observed successful magnetophoretic separation of microalgal cells from freshwater and/or seawater for all the cases as long as XDLVO analysis predicts particle attachment. For both the conditions, no pH adjustment is required for particle-to-cell attachment.
authors.affiliation: School of Chemical Engineering, Universiti Sains Malaysia, Nibong Tebal, Penang 14300, Malaysia. chjitkangl@usm.my.
authors.forename: Pey Yi
authors.initials: PY
authors.lastname: Toh
authors.forename: Bee Wah
authors.initials: BW
authors.lastname: Ng
authors.forename: Abdul Latif
authors.initials: AL
authors.lastname: Ahmad
authors.forename: Derek Chan Juinn
authors.initials: DC
authors.lastname: Chieh
authors.forename: JitKang
authors.initials: J
authors.lastname: Lim
mesh_terms: D002469:Cell Separation; D002708:Chlorella; D003102:Colloids / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007700:Kinetics; D058116:Lewis Acids; D008280:Magnetics; D053768:Metal Nanoparticles / Q000737:chemistry; D058086:Microalgae / Q000166:cytology*; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D012623:Seawater; D012965:Sodium Chloride / Q000737:chemistry; D013499:Surface Properties
chemical_list: D003102:Colloids; D005290:Ferric Compounds; D007477:Ions; D058116:Lewis Acids; C000499:ferric oxide; D012965:Sodium Chloride