Treating cancer and other diseases with laser light is not considered routine in the clinical setting. New approaches using nanoparticles show some promise in improving existing techniques.
One technique is known as photothermal therapy (PTT). It converts laser light into heat that can target and kill tumor cells. Another technique is photodynamic therapy (PDT). It uses laser light to generate reactive oxygen species (ROS). It includes hydroxyl radicals, singlet oxygen, superoxide radicals and hydrogen peroxide. These can wreak devastation on tumor cells.
Scientists review the current status of the field of nanoparticle-enhanced PDT and PTT. They focus on combining the two techniques to achieve the highest level of treatment efficiency.
Scientists have been able to apply these types of phototherapies while also delivering drugs to sites in the body that are otherwise inaccessible, by combining PTT or PDT with nanomaterials. It is also possible to combine PTT and PDT into a single treatment. It creates an even more powerful treatment method.
The surface of the nanoparticle can be modified to attach a photosensitive molecule to the surface. This allows the absorption of light at a particular wavelength. Light is converted to heat, in the PTT method. The light creates ROS, in PDT. Sufficient ambient oxygen must be present to produce enough ROS to kill tumor cells, for PDT to be successful.
Factors that control the penetration depth include the shape of the beam, wavelength of the light, intensity of the laser and the radius of the beam.
A powerful approach is to combine PDT with traditional medical treatments to create photodynamic antibacterial chemotherapy.
The nanoparticles can be used to deliver chemotherapeutic agents or antibiotics to the tumor site. When light is applied, the antibiotics can be released to prevent infection in the treated area.