Hatton Group Member

Andre Ditsch
Graduate Student

Department of Chemical Engineering
Massachusetts Institute of Technology
Room: 66-321
77 Massachusetts Ave.
Cambridge, MA 02139 USA

Phone: (617) 253-8182
E-mail: aditsch@mit.edu

Personal Information and Interests

Education:
M.S.in Chemical Engineering Practice
Massachusetts Institute of Technology, 2002

B.S. Chemical Engineering
University of Nebraska, 1999

Academic Interests

Research Interests: Magnetic Nanoclusters for Recovery of Recombinant Proteins
Thesis Advisor: Alan Hatton, Daniel Wang, Paul Laibinis (Rice University)

Research Description

The magnetic fluids produced in my research are stable dispersions of magnetic nanoparticles in a carrier liquid consisting of ~10 nm magnetite (Fe3O4) particles, which are coated with a variety of random copolymers containing acrylic acid to both stabilize the particles in solution and provide favorable surface properties. The small size of the particles results in dispersions that remain suspended indefinitely in gravitational and moderate magnetic fields and leads to large surface areas per unit volume, making the particles ideally suited for use in adsorptive separations, due to high capacity for targeted solutes. Surface area is available without any internal pores; thus separations are not limited by pore diffusion and can be performed much more quickly than with standard porous materials. Additionally, the magnetic particles are small enough to easily flow around micron sized debris, and thus separations in "dirty" streams, such as fermentation broth, that are impossible with packed columns are done relatively easily with magnetic nanoparticles.


TEM Image of magnetic nanocluster

The focus of my research is on the use of scaleable magnetic fluids for use in complex media, such as fermentation broth. It has been found by previous members in the group that to efficiently recover the magnetic nanoparticles from solution (e.g. by magnetic filtration) clusters of 50nm or larger are needed. However, for use in complex, high ionic strength environments, such as fermentation broth, the nanoclusters must be extremely stable. Combining controlled clustering with extreme stability is a difficult task, but can be achieved by controlled addition of polymer during synthesis. I have developed models to predict the optimum molecular weight and feeding based on the kinetics of colloidal aggregation and polymer adsorption, allowing the prediction of optimal synthesis conditions for an arbitrary polymer.

Additionally, the adsorption of recombinant proteins, expressed in Pichia Pastoris fermentation, by the magnetic nanoclusters, as well as modeling and optimization of high gradient magnetic separation (HGMS) for recovery of the nanoclusters are current areas of research.


Schematic of process for recovery of proteins from unclarified fermentation broth. The magnetic nanoclusters are added directly to the fermentation broth, where desired proteins are adsorbed. The solution is then run through a high gradient magnetic separation (HGMS) device to capture the magnetic clusters along with the desired protein.