Probing temperature-sensitive behavior of pNIPAAm-coated iron oxide nanoparticles using frequency-dependent magnetic measurements

Slew-rate dependence of tracer magnetization response in magnetic particle imaging

“…Detailed synthesis and phase transfer methods have been reported previously. [8][9][10][11] The two samples studied in this work, named LS-1 and LS-1-3, were prepared in separate phase transfer reactions, from the same batch of magnetic cores and polymer coating. Immobilized nanoparticles (LS-1-3) were prepared by suspending the nanoparticles in dimethyl sulfoxide (DMSO) and then freezing at À20 C.…”

Monitoring colloidal stability of polymer-coated magnetic nanoparticles using AC susceptibility measurements

“…Curves of v 00 as a function of frequency had well defined Debye peaks corresponding to these two hydrodynamic diameters, thus confirming that the particles remained well dispersed above the LCST and their particle size decreased due to contraction of the polymer coating. Recently, Kalele et al [52] have made similar observations using magnetite nanoparticles obtained by a temperature decomposition method and coated with physisorbed pNI-PAM. Unfortunately, their plots of v 00 as a function of frequency show multiple relaxation peaks, indicating either that the particles relax through both possible mechanisms, that their samples are highly polydisperse with multiple size populations, or that significant aggregation is occurring both below and above the LCST.…”

“…Unfortunately, their plots of v 00 as a function of frequency show multiple relaxation peaks, indicating either that the particles relax through both possible mechanisms, that their samples are highly polydisperse with multiple size populations, or that significant aggregation is occurring both below and above the LCST. All of these limitations make interpretation of the observations of Kalele et al [52] difficult. Kalele et al [52] compare their results to measurements obtained through DLS, however, given that the AC susceptibility measurements indicate polydispersity and aggregation, they must have confronted significant problems in interpreting their DLS results to extract a particle size.…”

“…All of these limitations make interpretation of the observations of Kalele et al [52] difficult. Kalele et al [52] compare their results to measurements obtained through DLS, however, given that the AC susceptibility measurements indicate polydispersity and aggregation, they must have confronted significant problems in interpreting their DLS results to extract a particle size. In this contribution we discuss an alternate approach of using AC susceptibility measurements in studying changes in the state of a colloidal suspension.…”

Stimulus-responsive polymeric nanoparticles for biomedical applications

“…As a widely studied thermo-sensitive polymer, PNIPPAm is commonly used as a surface layer to encapsulate magnetic nanoparticles to prepare magnetic/thermal-responsive nanoparticles [83][84][85][86][87][88]. For example, Zhang et al fabricated magnetic cores with double bonds on the surface via the coprecipitation method.…”