The use of lasers, over the past few decades, has emerged to be highly promising for cancer therapy modalities, most commonly the photothermal therapy method, which employs light absorbing dyes for achieving the photothermal damage of tumors, and the photodynamic therapy, which employs chemical photosensitizers that generate singlet oxygen that is capable of tumor destruction. However, recent advances in the field of nanoscience have seen the emergence of noble metal nanostructures with unique photophysical properties, well suited for applications in cancer phototherapy. Noble metal nanoparticles, on account of the phenomenon of surface plasmon resonance, possess strongly enhanced visible and near-infrared light absorption, several orders of magnitude more intense compared to conventional laser phototherapy agents. The use of plasmonic nanoparticles as highly enhanced photoabsorbing agents has thus introduced a much more selective and efficient cancer therapy strategy, viz. plasmonic photothermal therapy (PPTT). The synthetic tunability of the optothermal properties and the bio-targeting abilities of the plasmonic gold nanostructures make the PPTT method furthermore promising. In this review, we discuss the development of the PPTT method with special emphasis on the recent in vitro and in vivo success using gold nanospheres coupled with visible lasers and gold nanorods and silica-gold nanoshells coupled with near-infrared lasers.

http://wiki.phy.queensu.ca/shughes/images/0/0f/Cancer_3.pdf

Plasmonic photothermal therapy (PPTT) using gold nanoparticles

The characteristics of CO2 lasers that render them interesting for surgical applications are reviewed. An instrument consisting of an integrated CO2 laser and beam manipulator, designed specifically for surgical research work, is descirbed. Operational characteristics of the instrument relevant to such work are reported. An accessory for endoscopic surgery is described and instrumentation for microsurgery is discussed. Surgical researches now in progress with this instrument are mentioned.

A CO2 laser for surgical research.

The use of thermal knives in surgery: electrosurgery, lasers, plasma scalpel.

THE radiation produced by a carbon dioxide laser can destroy tissue1–3; exposure to the unfocused beam results in a superficial lesion which develops the characteristics of a burn: erythema, oedema, blistering and charring. If the beam is focused to a spot of 1–2 mm in diameter it incises tissue to a depth of several millimetres, depending on the laser power and focus cone angle and the speed of incision4, but no visible damage is caused to adjacent tissues.

Incision of tissue by carbon dioxide laser.

In preliminary studies, the carbon dioxide laser with a specially devised surgical manipulator has been shown to have a great potential for surgical application, especially in neurosurgery. It can incise nearly all tissues, bore or drill, excise and vaporize as needed. Cancers, even when ulcerated and infected, can be made to disappear by vaporization or portions of neoplasms can be excised with the laser beam. Experimental, transplantable animal tumours and one human brain tumour have already been treated with this laser. Rapid cleaning of infected, scarred decubitus ulcers, followed by immediate placement of free or pedicle grafts is suggested as a means for eliminating the weeks of pre-operative preparation ordinarily necessary in such cases. Minimal lesions can likewise be made for functional neurosurgery or for other purposes. When used in conjunction with the operating microscope control is correspondingly increased. Action by the laser is swift, gentle and easily controlled. Damage from the beam can be confined to within a millimetre of its application. Small blood vessels are readily coagulated by the CO2 laser making oozing surfaces easier to handle. The disadvantages include the inability of the CO2 laser beam to traverse any tissue, including the transparent media of the eye, without damage. Deep structures must, therefore, be surgically exposed. Ignition of flammable materials, such as drapes, and damage to personnel must be prevented but this can be done quite simply. Among the many problems which remain are those related to the total removal of cancers without causing undue damage to surrounding structures and those related to wound healing especially for skin. The problem of bleeding from large vessels needs further study. A method for controlling the vaporization of neoplasms, using radioactive monitoring of the smoke produced, is suggested.

L. McClusky

Papers

Liver resection with the continuous wave carbon dioxide laser: some experimental observations.

Liver resection with the continuous wave carbon dioxide laser: some experimental observations