Biophotonics: Improving Dentistry, Diagnoses, And … Space Travel?

By John Oncea, Editor

Biophotonics, combining biology and photonics, revolutionizes dentistry, medical diagnostics, and space travel through advanced imaging, biosensing, and therapeutic applications.

Biophotonics is an interdisciplinary field that combines biology and photonics. It involves the study and application of optical techniques, particularly imaging, to understand and manipulate biological molecules, cells, tissues, and organisms.

The term was coined in the early 1990s, but the roots of this field can be traced back to the development of microscopy in the 17th century and the discovery of various optical phenomena like fluorescence and phosphorescence in the 18th and 19th centuries. The invention of lasers in the 1960s and the subsequent development of fiber optics, detectors, and other photonic technologies further advanced the field of biophotonics.

Over the past few decades, biophotonics has seen rapid growth and has enabled numerous applications in areas such as imaging, biosensing, and therapies, among others. It’s also benefited dentistry and medical imaging, two topics we look at here. Oh, and space travel. It’s benefitting space travel. We’ll look at that, too.

A Powerful Tool In Dentistry

Dentistry, driven by technological advancements, has witnessed significant changes in recent years. According to the National Library of Medicine (NLM), “In dentistry, biophotonics has emerged as a powerful tool that offers new possibilities for diagnosis, treatment, and research.

“One of the most significant contributions of biophotonics to dentistry is the early detection of dental diseases. Traditional diagnostic methods often rely on visual and tactile examination, which may not be sensitive enough to detect early-stage dental problems. Biophotonic techniques, such as fluorescence imaging and Raman spectroscopy, can provide valuable information about the health of dental tissues at a microscopic level.”

Biophotonics also offers precision in dental procedures, reducing patient discomfort, minimizing bleeding, and speeding up healing. It also aids in preventing and managing dental disease through biophotonic sensors and imaging techniques that allow for non-invasive and real-time monitoring of oral conditions. “For instance,” notes NLM, “photoacoustic imaging can be used to assess the vascularization of oral tissues, which is crucial for diagnosing conditions like oral cancer.”

Teeth whitening is another dental procedure in which biophotonics have played a role, specifically laser-assisted teeth whitening. The precise control offered by lasers ensures that the whitening agent is activated evenly across the teeth, resulting in a more uniform and aesthetically pleasing outcome.

Finally, dental restoration has been improved because of biophotonics. “Optical coherence tomography (OCT) is an imaging technique that provides high-resolution cross-sectional images of dental materials and tissues,” NLM writes. “Dentists can use OCT to evaluate the fit and adaptation of restorations like crowns, bridges, and fillings. This ensures that the restorations are precisely placed, reducing the likelihood of complications or the need for replacements.”

Advancing Medical Diagnostics

Biophotonic sensors are utilized in the medical industry in various technologies like fluorescence-based imaging, optical coherence tomography (OCT), surface plasmon resonance (SPR), and Raman spectroscopy depending on the specific use case. According to AZo Optics, “Biophotonic sensors utilizing OCT are used in ophthalmology for retinal imaging due to OCT’s high resolution and depth penetration, which enables detailed visualization of tissue structures, aiding in the early detection of abnormalities.

“SPR-based biophotonic sensors can detect changes in refractive index near the sensor surface, making them suitable for studying and real-time monitoring of binding events between biological molecules, like protein-protein interactions and drug development processes. Similarly, Raman spectroscopy can help characterize biomolecules, which can be crucial for cancer detection by analyzing the chemical composition of tissues to distinguish between healthy and diseased states.”

Three recent advancements in biophotonics sensors – advancements that allow for earlier, more accurate, and more repeatable results – are low-cost point-of-care biophotonic sensors, defected photonic crystals in Dengue detection, and natural material-based biosensors. AZo explains these three advancements as follows:

• Low-Cost Point-of-Care Biophotonic Sensors: In a 2021 study, researchers developed optical biosensors using silicon nitride (Si3N4) waveguide-based sensor circuits with on-chip organic lasers. These low-cost devices aim to enable early disease diagnosis and public health protection through personalized medicine. The proof-of-concept experiment successfully detected different concentrations of fibrinogen, demonstrating the feasibility of this integrated sensor system.
• Defected Photonic Crystals in Dengue Detection: In a 2022 study, researchers explored the use of one-dimensional defected photonic crystals (1D PC) for medical diagnostics. The biophotonic sensor demonstrated the ability to differentiate between infected and normal blood samples. It showed high sensitivity, making it a valuable tool for rapid and accurate medical diagnostics in diverse applications.
• Natural Material-Based Biosensor: A 2021 study highlighted the importance of using natural materials like viruses, cells, and tissues to design biophotonic probes for precise imaging of cellular structures and sensitive detection of biological signals. It discussed bio-microlenses, cell-based biophotonic waveguides, and biological lasers as representative biophotonic probes. Biological lasers, utilizing naturally derived biomaterials, were singled out for their potential in bio-detection and imaging, particularly those based on viruses. Additionally, the study explored cell-based biophotonic waveguides for guiding light in biological systems, offering higher biocompatibility than traditional materials. Cell-based bio-microlenses were also discussed for label-free imaging of living cells and blood diagnostics.

Future advancements in diagnostics include the integration of machine learning and artificial intelligence which is expected to “enhance the interpretation of complex data generated by these sensors, which will further improve diagnostic accuracy.”

Biophotonics In Space

Biophotonics studies how electromagnetic radiation interacts with biological materials such as tissues, cells, and even subcellular structures and molecules in living organisms with one major benefit being its non-invasive nature when examining materials. Biophotonics has interesting applications, including its use in space. Four of those uses, according to Mars on Earth Project, are:

• Biomedical Imaging: Biomedical imaging in space missions is crucial for monitoring astronauts' health and diagnosing potential risks. Ultrasound devices are currently the primary biomedical imaging technique used in space due to their portability, real-time feedback, and lack of ionizing radiation. They are utilized for monitoring musculoskeletal health, cardiovascular function, and soft tissue injuries. Additionally, two-photon microscopy is employed to detect accelerated bone loss, a serious effect of microgravity during extended space flights. This imaging technique allows for high-resolution visualization of bone microstructure, enabling the study of changes in bone architecture and mineralization associated with bone loss. It also facilitates the visualization of individual bone cells and their interactions within the bone matrix, providing valuable insights for understanding the impact of microgravity on bone health during space missions.
• Spectroscopy: Spectroscopy is the study of how light and matter interact, allowing scientists to analyze the unique spectral signatures associated with different elements and molecules. Raman spectroscopy, in particular, involves irradiating a sample with a laser and measuring the scattered light to identify molecules and chemical bonds. In the context of space missions, Raman spectroscopy plays a crucial role in identifying microbial contaminations in spacecraft, ensuring the safety of the crew during long-duration missions. This technique helps analyze the changing microbial consortium in spacecraft and prevent infections. Additionally, astronomers use spectroscopy to study distant planets, analyzing absorption and emission lines to deduce their atmospheres. This analysis provides valuable information about a planet's habitability and the potential existence of life based on the detection of specific molecules closely associated with living organisms. Therefore, spectroscopy serves as a vital tool for both space exploration and the search for extraterrestrial life.
• Therapeutic Applications: Pharmaceuticals play a crucial role in treating various illnesses and injuries, including in space missions. Biophotonics, specifically photodynamic therapy (PDT), is being explored to treat infections, injuries, and wounds using drugs sensitive to specific light wavelengths. PDT helps to selectively target and destroy damaged cells through non-invasive means. The use of photosensitizing agents to produce reactive oxygen species in target tissues is a key aspect of this therapy. PDT is currently used for treating cancers, skin conditions, and microbial infections. Furthermore, the Kristallizator program by the State Space Corporation Roscosmos has successfully produced single protein crystals ideal for X-ray diffraction analysis. This has helped scientists identify the structure of a target protein for anti-tuberculosis drugs, potentially aiding in the development of effective tuberculosis treatments. These advancements highlight the important role pharmaceuticals and Biophotonics play in medical research, from improving astronaut well-being in space to developing treatments for terrestrial illnesses such as tuberculosis.
• Biosensing: Biosensing involves the detection and measurement of biological molecules and organisms, such as proteins, DNA, cells, and pathogens. Biosensors can generate and detect optical signals to provide information about the concentration or activity of the sample. In low earth orbit space missions, biosensors are used to study the effects of deep space on biological samples. For instance, dielectric spectroscopy is employed to research the impacts of microgravity and radiation on biological samples. This method takes advantage of cells' ability to be polarized when exposed to an electric field, which changes the overall capacitance of the cell suspension. The capacitance changes as cells undergo various biological processes, and dielectric spectroscopy correlates these changes to capacitance measurements. This technique is one of many methods used to measure biologically relevant data in space and can be miniaturized and automated for space missions. Overall, biosensing and related techniques play a crucial role in understanding biological processes in space environments.