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Communication Dans Un Congrès Année : 2019

Enhancing microfluidic separation of magnetic nanoparticles by molecular adsorption

Résumé

Microfluidic manipulation of magnetic nanoparticles is a smart tool for various environmental and biomedical applications, such as water remediation from pollutant molecules (heavy metals, pesticides, …), high-sensitivity immunoassays, cancer treatment by controlled drug delivery, hyperthermia or mechanical destruction of cells, protein purification, gene transfection, etc. In most of these applications, magnetic nanoparticles bear on their surface adsorbed molecules (either pollutants or biomolecules), which should either be delivered to the target site (drug delivery, gene transfection) or be extracted from the solvent (immunoassays, protein purification, water remediation). Unfortunately, these technics have strong limitations related to low efficiency of the magnetic manipulation of nanoparticles because of their strong Brownian motion and low efficiency of their separation from the suspending fluid (magnetic separation) under flows in microfluidic devices. However, molecules adsorbed on the nanoparticle surface often reduce repulsive colloidal interactions between nanoparticles and provoke a weak agglomeration of nanoparticles. Such agglomeration in the absence of applied magnetic field leads to an increase of the effective size of nanoparticles (or rather primary aggregates) and, once the magnetic field is applied, the magnetic force acting on primary aggregates is strongly amplified as compared to the situation of single non-aggregated nanoparticles. In this case the adsorbed molecules not only fulfill their function in water remediation or biomedical applications but allow a drastic enhancement of nanoparticle manipulation by magnetic fields, thereby broadening the application fields of nanoparticles. In the present work, we consider two different systems which follow the aforementioned behavior: iron oxide nanoparticles (of an average size of 8 nm) with either methylene blue (MB) dye adsorbed on their surface or monoclonal antibodies (AB) grafted on their surface and destined for realization of immunoassays. Dynamic light scattering (DLS), zeta-potential measurements along with experiments on kinetics of primary (at zero field) and secondary (field-induced) aggregation and microfluidic magnetic separation allow assessing the quantitative effect of the surface coverage of nanoparticles by MB or AB on the efficiency of nanoparticle clustering and magnetic separation in the presence of external magnetic fields as low as 5-10 mT.
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Dates et versions

hal-02426134 , version 1 (01-01-2020)

Identifiants

  • HAL Id : hal-02426134 , version 1

Citer

J. Queiros Campos, L Checa-Fernandez, Ch Hurel, C. Lomenech, A. Bée, et al.. Enhancing microfluidic separation of magnetic nanoparticles by molecular adsorption. International Conference on Magnetic Fluids 2019, 2019, Paris, France. ⟨hal-02426134⟩
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