Abstract
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The development of techniques using light related to living matter is called “biophotonics.” 2 Although actually ancient, biophotonics as a science is considered new, and is the result of an interface among physics, chemistry, and biology. Despite its not being a new field, there is still much to be studied and learned. The use of light as an essential tool in the health field has progressed following the technological advances of light sources and the scientific understanding of these phenomena.
The development of quantum physics, the genomic revolution, and, especially, molecular genetics in the late twentieth century technological revolution were of the utmost importance for the birth of biophotonics.
Physics faced scientists with different concepts, which did not make use of intuition. It enabled the understanding of molecular structure and how molecules interact with light, transferring energy that may be accumulated in the electrons, given back to the environment, or transformed by chemical reactions. The establishment of the basic rules that rule the microscopic world in the atomic scale was fundamental to understanding the macroscopic world, including living beings. The technological revolution began in the 1950s. Suddenly scientific results started being explored by companies, which boosted science to another level.
Laser, since its beginning, put physics and biology in close contact, because it allows a precise exchange of information at a molecular level. Laser also promoted a fast growth of photonics, with solid demonstrations of the power of optics in all areas. Fiberoptics and optics communications became mass products. Eventually, a genomic revolution was started by Watson and Crick when they determined the molecular bases of life, and this continues to date.
Genomics changed the outlook on life. Biology can no longer be considered as a science different from the exact sciences. To understand life, it is necessary to apply basic concepts of physics and chemistry. Atoms and molecules are at the base of everything, and light is the main communication between them. Therefore, light became an essential tool when we talk about life, which certainly helped develop understanding of the basic processes of interaction between light and life from the molecular point of view.
Laser, which is a tool whose mechanism is based on the interaction between luminous radiation and living matter, brought on a new revolution, because few modern scientific feats have such a broad range of applications. Many research centers 3 around the world are exclusively dedicated to the study of laser and its uses, and several publications, such as Photomedicine and Laser Surgery, have flourished.
It is feasible that in the future, laser will be implanted in the human body to make diagnoses as well as for healing purposes.
For many centuries, medicine and odontology 2 have made use of low technology tools, and many surgical instruments have simply changed in appearance. However, in the last decades, because of electronics, biochemistry and physics, laser, and light-emitting diodes (LEDs) leading this transformation, these areas have highly benefited surgery in particular, because laser is an excellent instrument for cutting and vaporizing tissues. Ophthalmic surgeries have achieved a high rate of success because of lasers. In oncology, lasers have been routinely used in treatments and diagnostics of several kinds of tumors. In urology, stones are removed through shock waves caused by intense light pulses, and in cardiology, arteries are in routine procedures. The precision of light allows the invasion of the cells' interior, and the performance of microalterations.
Since the beginning of laser therapy or phototherapy in the 1970s, through research by Endre Mester and scientific bases widely reported by Tina Karu and many others, its benefits have been evident. 4
In his editorial, Enwemeka 5,6 states very clearly the role of phototherapy in the modern world, and how beneficial it has proved to be for people's well-being.
Lately, many authors have published excellent results with laser and LEDs in the prevention and/or treatment of oral mucositis 7 –9 as a result of radio- and chemotherapy. It is a low-cost therapy that not only repairs soft and hard tissue, but also heals pain and palsy.
Recent studies conducted by Rochkind 10 showed results that may suggest that it could be possible to restore nervous cell damage and enable patients to walk again.
The control of microorganisms is currently one of the most researched areas of pharmacology. Throughout history, a significant part of modern civilization was destroyed by an uncontrolled attack of microorganisms and new threats emerge every day. The chemical antimicrobial industry is constantly alert because of the evolution capacity and variety of existing pathogens. The number of pathogens resistant to chemical agents increases the death rate following infections that were easily treated in the past, because despite technology, they seem to be growing stronger, and pharmaceutical resources may be achieving their limit. Some kinds of pneumonia in hospitals do not respond to traditional antibiotics, and biophotonics could make a difference in such situations in which microbiological control is necessary.
Photodynamic therapy (PDT) 11 –13 involves the use of a photosensitizer with an affinity for malign cells, a light source for excitation, and oxygen. The photosensitizer's molecules are activated by light, and start a process of energy exchange with the oxygen's molecules, producing a reactive kind of oxygen, singlet oxygen, which quickly and efficiently oxidizes almost all biological substrates in its way, a fast and safe process of killing cells. This same principle is now being used to kill microorganisms.
Phototherapy can also be efficient in killing fungi such as Candida albicans, responsible for systemic candidiasis that affects especially immunosuppressed patients; parasites such as Plasmodium falciparum, responsible for malaria, and Trypano-soma cruzi, responsible for Chagas disease; and bacteria such as those present in the oral cavity, responsible for caries and periodontal disease. This technique is considered the best alternative for treating local infections, and odontology could make great use of it.
One of the advantages of using antimicrobial photodynamic action is that death of bacteria can be controlled and restricted to the irradiated area, avoiding unnecessary damage and resistance to treatment. Another advantage is the fact that it can be applied numerous times with no side effects, which avoids systemic reactions to certain kinds of drugs. It seems to be the right solution when local and quick control of microorganisms is needed.
The Great Leap
Light sources are used for diagnostics and treatment of several pathologies in a quick and efficient way. Nowadays it is possible to clinically measure, through laser fluorescence, bone density and bacteria levels, and diagnose some kinds of cancer that do not need biopsies and molecular diagnosis with Raman spectroscopy. In the near future, it will be possible to perform blood tests by simply using a drop of blood.
Biophotonics surprises with new treatment techniques in the medical, physical therapy, and dental fields. The more we study the human body, the more we feel the need to understand the physical chemical mechanisms as well as develop less invasive procedures.
It is impossible to evaluate how far we will still travel. However, the development of biophotonics is far from over. Being aware that light is the main communication medium among physics, chemistry, and cellular engineering, we may conclude that this knowledge is essential whenever we talk about life.
Because of the growth of the population's life expectancy and the change in life habits, it is of utmost importance to have light as our main ally.
Footnotes
Acknowledgment
We thank Fatima Zanin for contributing to this editorial.