Photothermal Effects of High-Energy Photobiomodulation Therapies: An In Vitro Investigation

Abstract

The purpose of this study was to investigate photothermal aspects of photobiomodulation therapies (PBMT) in vitro to assist in the development of safe clinical parameters with respect to higher-power devices with large surface applicators. Laser wavelengths in the range of 650 nm–1064 nm were investigated using a thermal camera. Thermographic measures of surface and sub-surface temperature variations of similar lean porcine muscle tissue samples were recorded for a series of calibrated experiments. A thermal comparison was then made between Flat-top and Gaussian beam spatial distribution devices. Outcome data were subjected to statistical analysis using an ANOVA model. Results acquired at similar parameters of irradiance indicated that the application of the 980 nm wavelength was associated with the highest rise in temperature, which decreased with other wavelengths in the order 980 > 1064 ≈ 650 >>> 810 nm (p < 5 × 10−20). All wavelengths assessed were associated with a significant temperature increase, and with the exception of 810 nm, all exceeded the threshold of a 6 °C rise within the prescribed parameter limits. Optical scanning by movement of the applied source over a relevant area was found to offer effective mitigation of these temperature increases. An extended discussion is presented, analysing the clinical significance of the study outcomes. Recommendations are made within the limits of this in vitro study in order to assist future clinical investigations.

Spectral Characterization of a Blue Light-Emitting Micro-LED Platform and Microbial Chromophores for Therapeutic Applications in Skin Conditions

“…Titanium dioxide (used as nanoparticles in the scatter membrane) exhibits a series of beneficial properties, not only does incorporation into PDMS provides potential for incorporation into a wearable flexible device suitable for clinical application (38), but also potentiates light delivery without increasing thermal output from a light source. Resulting in the application of a model system capable of discerning wavelengthspecific effects on biological outputs, rather than potential undesired thermal effects (39). It also offers a dual advantage, in which photocatalysis of TiO₂ has proven to induce the production of reactive oxygen species (ROS).…”

Spectral characterization of a blue light-emitting micro-LED platform on skin-associated microbial chromophores

“…Titanium dioxide (used as nanoparticles in the scatter membrane) exhibits a series of beneficial properties, not only does incorporation into PDMS provides potential for incorporation into a wearable flexible device suitable for clinical application [ 38 ], but also potentiates light delivery without increasing thermal output from a light source. This resulted in the implementation of a model system capable of discerning wavelength-specific effects on biological outputs, rather than potential undesired thermal effects [ 39 ]. It also offers a dual advantage, in which photocatalysis of TiO 2 has proven to induce the production of reactive oxygen species (ROS).…”

Gold nanomakura: nanoarchitectonics and their photothermal response in association with carrageenan hydrogels

“…Therefore, it can be assumed that AuNMs due to their outward concave growth at the edges provided more surface area and greater stability in k-CG hydrogels, leading to greater photothermal response as compared to that of AuNRs. The intactness and ability of AuNMs to exhibit photothermal conversion even after incorporation into k-CG hydrogels show a possible use of the designed nanostructures for therapeutic purposes in the wavelength window of 600–700 nm [ 30 ].…”