SUPPLEMENTARY MATERIAL
Rui Zhang,† Benjamin Fellows,‡ Nikorn Pothayee,*§ Nan Hu,† Nipon Pothayee,† Ami Jo,† Ana C.
Bohórquez,∥ Carlos Rinaldi,∥ Olin Thompson Mefford,‡ Richey M. Davis† and Judy S. Riffle*†
†Department of Chemistry, Department of Chemical Engineering, and Macromolecules
Innovation Institute, Virginia Tech, Blacksburg, VA 24061
‡Department of Materials Science and Engineering and the Center for Optical Materials Science
and Engineering (COMSET), Clemson University, Clemson, SC 29634
§Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders
and Stroke, National Institutes of Health, Bethesda, MD 20892
∥J. Crayton Pruitt Family Department of Biomedical Engineering and Department of Chemical
Engineering, University of Florida, Gainesville, FL 32611
*Corresponding Author E-mail: [email protected]
The experimental setup for calorimetric measurements is shown in Fig. S1. Data was
collected using an EasyHeat Induction Heating System produced by Ameritherm. The five-turn
induction coil contained a polycarbonate recirculating water bath designed to regulate sample
temperature. The temperature changes in each sample were measured using a fiber optic
temperature sensor from NeoptixTM. The sample was allowed to reach thermal equilibrium prior
to turning on the magnetic field. Temperature was recorded every five seconds. Measurements
were conducted at a frequency of 205 kHz and a magnetic field strength of 30 kA m -1 that was
verified using an AC field probe (AMF Life Science). The hexyl MGICs dispersion (3.5 mg mL-
1, 0.5 mL) was used to measure the heating rate. The SAR of the MGICs was calculated from its
heat capacity (C), the initial slope of the temperature versus time curve (ΔT/Δt, K s -1), and the
total mass of the MGICs dispersion, divided by the mass of iron as determined from ICP-AES.
[1]
Fig. S1 Experimental setup for calorimetric measurements
Synthetic methods for the monomers as well as the graft copolymers have been described in
our previous papers.[2, 3] The synthetic scheme for the hexylamino bisphosphonate methacrylate
monomer is shown in Fig. S2. The propylamino bisphosphonate methacrylate monomer can be
prepared by the same procedure, by using 3-amino-1-propanol instead of 6-amino-1-hexanol.
The acrylate-functional PEO oligomer was synthesized by reacting a commercial ~5000 Mn
poly(ethylene oxide) monomethyl ether with freshly-distilled acryloyl chloride.
Fig. S2 Synthesis of hexylamino bisphosphonate methacrylate monomer
Conventional free radical polymerization was utilized to synthesize the graft copolymers.
The phosphonate esters were then selectively hydrolyzed without affecting the carboxylic esters
by a mild approach previous reported by our group. The synthetic scheme for the polymerization
and selective hydrolysis is shown in Fig. S3.
Fig. S3 Synthesis of poly(hexyl ammonium bisphosphonic acid methacrylate)-g-PEO
copolymers
1H and 31P NMR spectra of the poly(propyl ammonium bisphosphonate methacrylate)-g-
PEO before and after phosphonate ester hydrolysis are shown in Fig. S4 and S5. The poly(hexyl
ammonium bisphosphonate methacrylate)-g-PEO had similar spectra. Due to solubility issues,
the graft copolymers before and after selective hydrolysis were analyzed in different deuterated
solvents. The 1H NMR spectra featured the disappearance of protons corresponding to the methyl
and methylene groups of the phosphonate esters (peaks h and i in the top spectrum in Fig. S4).
The methyl protons (peak i) had a chemical shift at ~1.3 ppm, and this peak completely
disappeared after hydrolysis. The methylene protons on the phosphonate esters (peak h) had a
chemical shift of 4 ppm, very close to the methylene proton resonance on the carboxylic ester of
the bisphosphonate graft segment (peak c). Before hydrolysis, peaks c and h combined indicated
that 10 Hs per phosphonate monomer unit were present. After selective hydrolysis, only 2 Hs
remained due to the carboxylic ester methylene. This was confirmed by the integrals in the
spectra. The protons on the poly(ethylene oxide) segment (peaks l and m) remained unchanged,
indicating that the carboxylic esters on the PEO segment were not affected by the hydrolysis
procedure. The spectra indicated that the phosphonate esters had been selectively deprotected,
with little to no effects on the carboxylic esters. 31P NMR spectra (Fig. S5) further demonstrated
the success of the removal of the phosphonate esters. The single phosphorus resonance shifted
from 31 to 16 ppm, which was in good agreement with our previous study with polymer end
groups.[2]
Fig. S4 1H NMR spectra show successful deprotection of the phosphonate esters of the
poly(propyl ammonium bisphosphonate methacrylate)-g-PEO copolymers with minimal effect
on carboxylic esters
Fig. S5 31P NMR spectra of the poly(propyl ammonium bisphosphonate methacrylate)-g-PEO
The 1H NMR spectrum of the PEO-g-PAA is shown in Fig. S6. The integrals indicated that
there were ~75 acrylate repeat units per PEO graft. Based on this, the graft copolymer contained
about 50 wt% of PEO and 50 wt% of poly(sodium acrylate).
Fig. S6 1H NMR spectrum of the PEO-g-PAA
Fig. S7 Additional representative images of MGICs following complexation with copolymers
that led to a cluster formation.
[1] E. C. Vreeland, J. Watt, G. B. Schober, et al., "Enhanced Nanoparticle Size Control by Extending LaMer’s Mechanism," Chemistry of Materials, vol. 27, no. 17, pp. 6059-6066, 2015.[2] N. Hu, L. M. Johnson, N. Pothayee, et al., "Synthesis of ammonium bisphosphonate monomers and polymers," Polymer, vol. 54, no. 13, pp. 3188-3197, 2013.[3] N. Pothayee, N. Pothayee, N. Hu, et al., "Manganese graft ionomer complexes (MaGICs) for dual imaging and chemotherapy," Journal of Materials Chemistry B, vol. 2, no. 8, pp. 1087-1099, 2014.
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