The combination of nanotechnology with laser light creates a powerful effect on cancer cells

Treatment of cancer and other diseases with laser light is currently not considered routine in the clinical setting, but new approaches using nanoparticles show promise for improving existing techniques.

One technique, known as photothermal therapy (PTT), converts laser light into heat that can target and kill tumor cells. Another technique, photodynamic therapy (PDT), uses laser light to generate reactive oxygen species (ROS), such as hydroxyl radicals, singlet oxygen, superoxide radicals and hydrogen peroxide, which can destroy tumor cells.

In Applied physics examsby AIP Publishing, a multinational team of researchers reviews the current state of the field of nanoparticle-enhanced PDT and PTT and focuses on combining the two techniques to achieve the highest level of treatment efficacy.

By combining PTT or PDT with nanomaterials, researchers have been able to apply these types of phototherapies while delivering drugs to otherwise inaccessible body sites. It is also possible to combine PTT and PDT in one treatment, creating 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. In the PTT method, this light is converted into heat. In PDT, light creates ROS. For PDT to be successful, enough ambient oxygen must be present to produce enough ROS to kill tumor cells.

“In cancer therapies using this strategy, the depth of laser light penetration into the tissues is critical in determining therapeutic efficacy,” said author Masoud Mozafari, from Iran University of Medical Sciences.

Factors that control penetration depth include beam shape, light wavelength, laser intensity, and beam radius.

A powerful approach is to combine PDT with traditional medical treatments, such as chemotherapy, to create photodynamic antibacterial chemotherapy.

The nanoparticles can be used to deliver chemotherapeutic agents or antibiotics to the tumor site. When light is applied, generating ROS molecules in the tumor and killing both tumor cells and bacteria, antibiotics can be released to prevent infection in the treated area.

Other modifications to the surface of the nanoparticles could allow it to cross the blood-brain barrier in order to treat brain tumours.

One set of studies reviewed in this work involved gold nanorods that had a rabies virus glycoprotein attached to their surface. Since this virus naturally infects the brain, the gold nanorods were able to penetrate the blood-brain barrier and target the brain tumor. Applying light from a laser then allowed the nanorods to generate localized heat, killing the tumor cells.

These techniques can also be used to treat other medical conditions, such as atherosclerosis, scar removal, abscesses, non-healing ulcers, or dental infections.

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Material provided by American Institute of Physics. Note: Content may be edited for style and length.

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