Hyperthermia Flashcards
Explain the rationale for hyperthermia treatment of cancer and how can nanotechnology be used to implement it?
Normal cells they can survive temperatures up to 42 degrees before proteins start to degrade. Cancer cells are more sensitive to heat –> idea with hyperthermia treatment is that cancer cells are targeted and killed in a controlled way without damaging healthy tissue.
There are two ways to create heat with nanoparticles, with magnetic field or light. But the principle is the same – you hit the cancer cells a little more.
Provide at least 3 factors that are hindering for successful implementation of hyperthermia therapy
-Hard to accurately measure the temperature inside a tumor
-Hard to keep an area at constant temperature without affecting nearby tissues
-Not all body tissues respond the same way to heat – for instance the brain is very sensitive to heat
Define eddy currents and nanosize-dependent non-specific heating due to eddy currents for magnetic NPs
Eddy currents are loops of electrical current induced within conductors by a changing magnetic field. Eddy currents flow in closed loops within conductors, in plane perpendicular to the magnetic field
For nano-sized materials below critical size, the eddy current heating is extremely weak due to poor electrical conductivity to produce a noticeable induction heating as nanoparticles cannot generate a substantial electrical voltage
Smaller particle –> larger distance between energy levels –> less conductive –> less heat generated
What is Neelian and Brownian relaxation?
Neelian: Magnetic spin, single domain. Changes
inside particle flip change –> produce heat
Brownian: Entire particle is moving when the magnetic field is changing. Movement of the entire particle produces heat.
Down side, viscosity – may not be able move
Which magnetic materials are desired for hyperthermia treatment: single- or multi-domain?
Single domains (only one magnetic spin)
Particle less than 20-25 nm –> super paramagnetic
What is the typical size range for superparamagnetic nanomaterials?
Superparamagnetic nanomaterials are below 25 nm
Which material is the most common material for producing magnetic hyperthermia in clinical practice?
Iron oxide nanoparticles
SPIONS, Super paramagnetic iron oxide nanoparticles
List at least three critical magnetic parameters for hyperthermia generation?
Critical magnetic parameters for hyperthermia:
- Magnetic properties of material
- Applied magnetic field strength
- Applied magnetic field frequency
- Atkinson-Bregovic safety limit – how much magnetic field can be applied to humans!
Also
- Type of material and its heat capacity
- Size of NP
- Dynamic viscosity of the medium
Describe the details of NanoTherm treatment, clinical indication, etc.
This is for treatment of a brain cancer. Open brain and inject NPs, SPIONs Surface coated iron oxide nanoparticles. Applied directly in the brain tumor or in the area after surgical resection
- Patient placed in magnetic field
- Particles vibrate –> flip and create heat. Burn away cancer tissue
- If not eliminated by the heat at least it is made more sensible to other treatments
- Iron oxide dissolves over time, enough for treatment of a few weeks. Non toxic.
- One injection -> several treatments,
In your own words, describe surface plasmon resonance? What is plasmon?
When electric fields of light are directed at nanoparticles, the surface plasmons become excited and begin to resonate.
The oscillation that occur when light shines –> electron cloud resonate and start to move together,
Plasmon is the quantum of plasma. Cloud around particle = plasmon –> start to move with the light-wave.
