Effective Transmission of Light for Media Culture, Plates and Tubes

Abstract

The results of many investigations on low-level laser therapy are contradictory and this is due to the large number of illumination parameters as well as the inability to measure the possible effects after irradiation with the necessary objectivity and the fact that the light needs to pass thorough barriers (usually the plastic of the culture dish/plate and culture medium) to reach the cells. In this manner, the objective of this study was to determine the absorption coefficient, penetration depth and effective transmission in materials commonly used in cell cultures. Among the most commonly used wavelengths in low-level laser therapy, the lowest absorption coefficients were reached by DMEM and RPMI (α = 0.03 cm(-1)), from 633 to 690 nm, which reach an effective transmission of 93% of incident radiation and penetration depth of 33 cm. Among the solid materials in the same range of the electromagnetic spectrum, the lowest absorption coefficient was obtained for the polystyrene (Petri dish and well plate), with α = 1.31 cm(-1), 78% of effective transmission and 0.76 cm of penetration depth. This article also presents a simple equation for estimating the amount of energy that will actually reach the sample.

Photobiomodulation and different macrophages phenotypes during muscle tissue repair

“…The effects of PBM on macrophage phenotypes are beginning to be described in cell cultures studies,10, 30, 31, 32, 33, 34 evidencing that this therapeutic modality, especially using the NIR wavelength, is capable of altering the polarization of these cells in vitro. In vivo experiments have demonstrated that PBM (808 nm) can shift the phenotype of brain microglial polarization from the pro‐inflammatory phenotype (M1) to the anti‐inflammatory (M2) phenotype after ischemic stroke, promoting cortical neurogenesis 35.…”

Photobiomodulation with 660-nm and 780-nm laser on activated J774 macrophage-like cells: Effect on M1 inflammatory markers

“…There are only a few articles that consider the effective transmission of radiation in the discussion of results from in vitro studies [35,48]. In the present study, we took into consideration the loss due to the polypropylene wall of the Falcon tube in order to compare the dosimetry that actually reached the cells with previous studies that provided sufficient information to determine the dosimetry used.…”

“…Table 1 displays the effective energy (amount of energy that actually reached the cells after passing through the polypropylene tube), which was calculated based on Silva et al [35]. In brief, for determination of effective transmission of radiation by Falcon tube (polypropylene thickness of 1 mm) the following equation was used: $$I_t=I_{0}false[false(1-Rfalse)e^{-\propto ․Z}-Rfalse]$$ where I 0 is the photon flux normally incident on the sample, α is the absorption coefficient of polypropylene (α 660 = 1.96 cm −1 and α 780 = 1.79 cm −1 ) and z is the optical path (1 mm).…”

Oil-based gel phantom for ultrasound and optical imaging

“…Phantoms with higher concentration of SEBS (> 10%) and in the absence LDPE presented optical properties similar to that of pure water, in which no significant absorption (or scatter) is observed in the 400 -900 nm range 11 . At 900 nm and 1200 nm regions all phantoms presented absorption peaks (figures 4(a) and 4(b)), which are also similar to those found in water.…”

“…At 900 nm and 1200 nm regions all phantoms presented absorption peaks (figures 4(a) and 4(b)), which are also similar to those found in water. The water's absorption peaks in these regions are mainly due to the resonant molecular vibration of the O-H bond 11 . Besides the small increase in the absorption, the addition of LDPE has a higher impact on the optical scatter coefficient of the compounds, especially in the blue-violet region of the spectrum ( figure 5(b)).…”