(263d) Designing Magnetic Nanoparticles for Bioseparation

Maghemite &gamma-Fe2O3 nanoparticles of various sizes (tunable down to 5nm) and silica coating morphologies were synthesized via one-step Flame Spray Pyrolysis (FSP). The nanostructures produced exhibited superparamagnetism and were characterized with TEM, XRD, VSM, Zeta potential analyzer, BET surface area instrument and acid dissolution test. The feasibility of these nanoparticles for protein adsorption and desorption was tested using Bovine Serum Albumin (BSA) as a model protein. Sol-gel coating method was employed as a comparison. Particle surface area was found to be the controlling physical property for adsorption and a maximum BSA binding capacity of 290mg/g particles was obtained. Presence of carbodiimide (CDI) coupling agent mildly enhanced the adsorption onto bare maghemite. Effect of surface properties was studied with various buffer systems; phosphate buffer was found to suppress surface charge variation among different particles due to specific adsorption of phosphate group onto bare maghemite particles. Significant higher BSA binding capacity on maghemite particles was noticed with formate-based buffers, which kept the particle surface to be positively charged, suggesting that manipulating the surface charge properties is an effective mean to enhance protein adsorption. The paper also investigated the separation efficiency of such nanoparticles under a magnetic field and compared the effectiveness of different eluting agents in terms of protein desorption and particle regeneration. Further functionalisation routes and particle-protein interactions were discussed and it is highlighted that the ultimate choice of the nanostructures depends on the particular application and the biomolecules involved.