Abstract
Surface derivatized magnetic nanoparticles have been commonly used for magnetic separation. Facile mechanisms are needed to be developed for the design of bio-functionalized magnetic hybrid materials, where the surfaces can be re-generated for the re-use of the developed platforms. Superparamagnetic iron oxide nanoparticles with a diameter below 10 nm were synthesized via a novel microwave-assisted hydrothermal method in the presence of citrate ions, which allowed to obtain uniform and negatively charged nanoparticles. These were then coupled with Poly-l-lysine (PLL), forming micrometer-sized self-assembled spherical entities. Cross-linking the PLL within these microspheres with glutaraldehyde stabilized them chemically and mechanically. The active bio-functionality was introduced by a protein grafting methodology, using m-maleimidobenzoyl-N-hydroxysulfosuccinimide ester (SMBS). The Moringa oleifera Coagulant Protein (MOCP) from a seed extract was employed for its characteristic coagulation activity. The performance of the MOCP functionalized microspheres was evaluated as a function of turbidity removal of problematic colloidal clay from water via magnetic separation, resulting in over 80% of activity within 15 min. Surface of these hybrid materials can be re-generated by treatment with alcohol, allowing their easy magnetic separation and re-use. The rapid and strong response with tunable magnetic property makes these hybrid microspheres a powerful tool for many potential applications, due to the general applicability of the developed methodology.
Highlights
Nanoparticles (NPs) have widely been applied to develop novel environment-friendly methods and techniques
A wide variety of analytical techniques was used to evaluate the crosslinking with the target protein and a possible biological and promising application in water treatment for turbidity removal was demonstrated
Using the Scherrer equation a crystallite size of 6.2 nm was obtained. This value is in a good agreement with the average value of 6.1 nm obtained from Atomic force microscopy (AFM)
Summary
Nanoparticles (NPs) have widely been applied to develop novel environment-friendly methods and techniques. These constitute an advancement to traditional manufacturing, dramatically reducing the contamination or negative impact,. The high surfaceto-volume ratio of nanoparticles enables novel properties which can be tuned by their size control. Superparamagnetism (SPM) is a desired characteristic of magnetic NPs, where colloidal stability and magnetic field responsive particles are deemed essential, especially in biological (Neuberger et al 2005; Lu et al 2017) and environment-related applications (Yantasee et al 2007). The synthesis methods can be tuned to obtain NPs with size and surface properties adjusted to a specific application. MW assisted hydrothermal method was recently used for a highyield synthesis of high quality and water dispersible SPIONs (Carenza et al 2014)
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