Magnetic Nanoparticles as Nanoscale Probes and Actuators in Complex Fluids and Biological Systems

Date(s) - 11/28/2011
11:45 am - 12:35 pm

Dr. Carlos Rinaldi, Department of Chemical Engineering, University of Puerto Rico, Mayagüez


Magnetic nanoparticles are of interest in a variety of applications which take advantage of their manipulation using externally applied magnetic fields. Depending on the material used, these nanoparticles may possess either a freely rotating magnetic dipole or a dipole pointing in a fixed particle-locked direction. Their response to magnetic fields depends on the nature of the magnetic material, their coating, and the viscous properties of the suspending medium. In this talk I will summarize our recent work on the response of magnetic nanoparticles in suspension and subjected to time-varying magnetic fields through two topics. First, the dynamic response of magnetic nanoparticles with particle-locked dipoles in oscillating magnetic fields can be used to obtain information of the mechanical properties of the surrounding fluid. This is demonstrated through experiments in which properly functionalized nanoparticles are used to determine the liquid-solid transition temperature in a physical gel and to quantitatively determine the viscosity “felt” by nanoparticles suspended in simple and complex fluids. In the latter case deviations are seen between the nanoscale and macroscale viscosities. Second, application of high frequency and moderate to high amplitude magnetic fields to suspensions of magnetic nanoparticles results in conversion of magnetic energy to thermal energy, resulting in a localized increase in temperature. Such an effect can be applied to the treatment of certain diseases such as cancer. I will present part of our work on developing targeted magnetic nanoparticles which are biocompatible and colloidally stable in biological fluids and in vitro evaluation of the applicability of this novel form of treatment in destroying cancer cells.



Carlos Rinaldi obtained his undergraduate degree in Chemical Engineering from the University of Puerto Rico, Mayagüez, in 1998 with top honors. Later he attended the Massachusetts Institute of Technology where he participated in the David H. Koch School of Chemical Engineering Practice (MSCEP 2001), and completed an MS (2001) and PhD (2002). He was awarded the J. Edward Vivian Award for Exemplary Performance and Commitment to the David H. Koch School of Chemical Engineering Practice. In the summer of 2002 he served as Assistant Station Director for the MIT Practice School in Mitsubishi Chemical Corporation, Mizushima, Japan. In the fall of 2002 he joined the Department of Chemical Engineering at the University of Puerto Rico, Mayagüez. Carlos Rinaldi has been recognized as one of the 2006 Presidential Early Career Award for Scientists and Engineers (PECASE) awardees, has been elected Distinguished Professor of Chemical Engineering at UPRM multiple times, and was recognized as an Emerging Scholar by Diverse Issues in Higher Education. Dr. Rinaldi’s research interests are in biomedical applications of magnetic nanoparticles and fundamental fluid physics of suspensions of magnetic nanoparticles. Students in his laboratory work on magnetic nanoparticle synthesis and functionalization, suspension hydrodynamics and rheology, and biomedical applications.