MWCNT-Hydrogel Nanocomposites: Synthesis, Characterization, and Radiofrequency Heating

Nanocomposites obtained by incorporation of nanoparticulates in hydrogel matrix are attractive biomaterials for a variety of biomedical applications including drug delivery, hyperthermia cancer treatment, sensors and actuators, and tissue engineering. In this study, we present a nanocomposite of hydrogels with multi-walled carbon nanotubes (MWCNT). MWCNT were dispersed in temperature responsive N-isopropylacrylamide hydrogels. Lower critical solution temperature (LCST) of the nanocomposites was tailored for physiological applications by addition of varying amounts of acrylamide. LCST shifted to higher temperatures with increasing amounts of acrylamide. Nanocomposites were characterized for dispersion, temperature responsive swelling, mechanical properties, and response to radiofrequency (RF) field at 13.56 MHz. Addition of nanotubes contributed to interesting properties including reduction in swelling due to MWCNT hydrophobicity. Addition of MWCNT increased mechanical strength and was dependent on loadings. The effect of MWCNT addition on mechanical properties of the nanocomposites was characterized over a range of temperatures. Application of RF resulted into nanocomposite heating and resultant temperatures were measured using infrared thermography. The heating ability of nanocomposites was proportional to amount of MWCNT.

In addition to N-isopropylacrylamide, poly(ethylene glycol) hydrogel nanocomposites were also synthesized. Swelling, mechanical, and RF heating properties of the nanocomposites were studied for different MWCNT loadings. Cytotoxicity of the nanocomposites was evaluated with direct contact method.