Electrospun cancer hyperthermia treatment

Cancer cells have been shown to be more sensitive to elevated temperature compared to normal cells and this has led to the development of using heat to treat cancer tumors [Hildebrandt et al 2002]. The heat applied is generally up to 45 °C. While clinical trials are underway to gain regulatory approval of this treatment method, researchers are exploring the potential use of electrospun fibers for this application. An advantage of electrospun fibers is that it may be delivered as injectable form which is minimally invasive [Ravichandran et al 2012].

Hela cells (Cervical cancer cells) on electrospun nanofibers.

For electrospun fibers to be used as hyperthermia treatment, it must be able to generate heat when activated by an external source. The most commonly explored method is to use an externally applied magnetic field to activate fibers. Magnetic nanoparticles may be incorporated into the electrospun fibers matrix to give it this functional capability. One of the most often used nanoparticles is iron oxide. Amarjagal et al (2013) incorporated 2mg/ml of Fe₃O₄ in electrospun polyurethane (PU) nanofibers and tested its heating rate under an alternating magnetic field. Under a 368 kHz alternating magnetic field, the 2mg/ml of Fe₃O₄ in electrospun polyurethane (PU) nanofibers was able to heat up to 41° in a minute. Heat generation by the nanoparticles within the polymer matrix may be attributed to two different heating mechanism. The first is from the rotation of the nanoparticles. The second is due to magnetization vector rotation or Neel relaxation [Amarjagal et al 2013]. Choi et al (2015) incorporated iron oxide nanoparticles into electrospun polyvinylidene fluoride (PVDF) with up to 20% wt nanoparticles concentration. When an alternating magnetic field with frequency of 355 kHz and 128 Oe was applied, a temperature up to 46.3 °C was reached.

In vitro tests have also supported the use of electrospun membrane in hyperthermia cancer treatment. Huang et al (2012) used electrospun polystyrene (PS) loaded with 20% iron oxide nanoparticles for their hyperthermia tests. The fibers were smooth with no evidence of nanoparticles leaching out over 14 days in PBS. The composite membrane was able to heat 1 ml of water from 23 °C to 83 °C in 180s when an alternating magnetic field of 27.1 kA/m and 232 kHz was applied. SKOV-3 ovarian cancer cells were seeded on the collagen coated PS/iron oxide nanoparticles to verify its hyperthermia performance. When an alternating magnetic field was applied, the medium quickly reached a temperature of 45 °C in two to three minutes and were maintained at that temperature. 100% cell death was observed after 10 minutes.