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The skin cross-section showing dermal penetration by different wavelengths of light (in order from the left: UVB, UVA, blue light, green light, yellow light, red light, infrared light).
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The invention of systems enabling the emission of waves of a certain length and intensity has revolutionized many areas of life, including medicine. Currently, the use of devices emitting laser light is not only an indispensable but also a necessary element of many diagnostic procedures. It also contributed to the development of new techniques for...
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... penetration of laser light in biological tissue increases with wavelength up to mid-infrared, where water that present in the tissues, absorbs the most energy of laser light. [17] (Figure 1). More specific knowledge of this interaction between laser and skin can help the specialist to select specific laser parameters in their therapies, such as the wavelength of the laser light, intensity, duration of radiation, and the density of laser beam energy [19]. ...
Citations
... A promising way to solve this problem is the search for new optical methods for the early non-invasive diagnostics and analysis of the human tissues' structures. One of these methods, which has significant potential to increase the efficiency of the early diagnosis of skin tumors, is confocal scanning Raman and photoluminescence (PL) microspectroscopy, with an excitation wavelength lying in the visible and near-infrared range (e.g., 532, 785, 1064 nm) [9][10][11][12][13][14][15][16][17][18]. ...
... The band intensity at 1655 cm −1 in BCC was unchanged relative to normal skin, but in SCC, it increased by almost 10%. The initially one band at 1745 cm −1 in normal skin was split into two bands each in BCC and SCC with decreased intensity, similarly to the case at 532 nm [12,15]. The intensity of other bands in the ~1800 cm −1 region decreased in both BCC and SCC. ...
... The measuring of Raman/PL spectra at 1064 nm has been widely used for the investigation of various human tissues, including tumors, without destruction (thermal damage, photo damage) [12,30,[32][33][34][35][36], because this wavelength is non-destructive and non-mutagenic. The Raman/PL spectra of normal skin, BCC and SCC were registered at 1064 nm laser excitation in the 900-3100 cm -1 range. ...
Confocal scanning Raman and photoluminescence (PL) microspectroscopy is a structure-sensitive optical method that allows the non-invasive analysis of biomarkers in the skin tissue. We used it to perform in vitro diagnostics of different malignant skin neoplasms at several excitation wavelengths (532, 785 and 1064 nm). Distinct spectral differences were noticed in the Raman spectra of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), compared with healthy skin. Our analysis of Raman/PL spectra at the different excitation wavelengths enabled us to propose two novel wavelength-independent spectral criteria (intensity ratios for 1302 cm-1 and 1445 cm-1 bands, 1745 cm-1 and 1445 cm-1 bands), related to the different vibrational "fingerprints" of cell membrane lipids as biomarkers, which was confirmed by the multivariate curve resolution (MCR) technique. These criteria allowed us to differentiate healthy skin from BCC and SCC with sensitivity and specificity higher than 95%, demonstrating high clinical importance in the differential diagnostics of skin tumors.
... Studies have shown that near-infrared light can penetrate biological tissues more effectively than visible light. 18,19 Existing interpretations suggest that light energy emitted by laser therapy devices is predominantly absorbed within the first 10 mm of biological tissue. This finding aligns with previous research indicating that laser light can penetrate several millimeters into biological tissues. ...
Introduction: The depth of laser light penetration into tissue is a critical factor in determining the effectiveness of photodynamic therapy (PDT). However, the optimal laser light penetration depth necessary for achieving maximum therapeutic outcomes in PDT remains unclear. This study aimed to assess the effectiveness of laser light penetration depth at two specific wavelengths, 532 nm and 660 mm. Methods: Chicken and beef of different thicknesses (1, 3, 5, 10, and 20 mm±0.2 mm) were used as in vitro tissue models. The samples were subjected to irradiation by a low-level laser diode of 532 and 660 nm in continuous mode for 10 minutes. with power densities of 167 and 142 J/cm2 , respectively. Laser light transmission through the tissue was measured using a power meter. Results: For beef samples, the 660 nm wavelength achieved a maximum transmission intensity of 30.7% at 1 cm thickness, while the 532 nm laser had a transmission intensity of 6.5%. Similarly, in chicken breast samples, the maximum transmission occurred at 1 cm thickness with 68.1% for the 660 nm wavelength and 18.2% for the 532 nm laser. Conclusion: Results consistently demonstrated a significant correlation (P<0.05) between tissue thickness and laser light penetration. Thicker tissues exhibited faster declines in light transmission intensity compared to thinner tissues within 10 minutes. These findings highlight the importance of further research to enhance light delivery in thicker tissues and improve the efficacy of PDT in various medical conditions.
... LED light-emitting devices have been widely studied for skin care and regeneration, with the literature describing the effect as varying based on the characteristics of the light, that is, light intensity, exposure time, and wavelength [14]. The wavelength used in skin treatment depends on the required penetration into the skin and the intracellular target [15][16][17]; however, the literature reveals that PBM testing is carried out in a variety of experimental settings which often fail to accurately measure this variable. ...
Starting from the discovery of phototherapy in the beginning of the last century, photobiomodulation (PBM) has been defined in late 1960s and, since then, widely described in different in vitro models. Robust evidence indicates that the effect of light exposure on the oxidative state of the cells and on mitochondrial dynamics, suggesting a great therapeutic potential. The translational scale-up of PBM, however, has often given contrasting and confusing results, mainly due to light exposure protocols which fail to adequately control or define factors such as emitting device features, emitted light characteristics, exposure time, cell target, and readouts. In this in vitro study, we describe the effects of a strictly controlled light-emitting diode (LED)-based PBM protocol on human fibroblasts, one of the main cells involved in skin care, regeneration, and repair. We used six emitter probes at different wavelengths (440, 525, 645, 660, 780, and 900 nm) with the same irradiance value of 0.1 mW/cm2, evenly distributed over the entire surface of the cell culture well. The PBM was analyzed by three main readouts: (i) mitochondrial potential (MitoTracker Orange staining), (ii) reactive oxygen species (ROS) production (CellROX staining); and (iii) cell death (nuclear morphology). The assay was also implemented by cell-based high-content screening technology, further increasing the reliability of the data. Different exposure protocols were also tested (one, two, or three subsequent 20 s pulsed exposures at 24 hr intervals), and the 645 nm wavelength and single exposure chosen as the most efficient protocol based on the mitochondrial potential readout, further confirmed by mitochondrial fusion quantification. This protocol was then tested for its potential to prevent H2O2-induced oxidative stress, including modulation of the light wave frequency. Finally, we demonstrated that the controlled PBM induced by the LED light exposure generates a preconditioning stimulation of the mitochondrial potential, which protects the cell from oxidative stress damage.
... They better penetrate pigmented tissue, making them appropriate for treating darker skin tones. Diode lasers have shorter wavelengths with a higher absorption in water and haemoglobin [43], thus making them more suitable for patients with lighter skin tones, as they are less likely to cause pigmentation changes [44]. ...
The purpose of this study was to evaluate the efficiency of two therapeutic procedures clinically and microbiologically in the management of periodontally affected teeth: scaling and root planing alone and the laser-assisted new attachment procedure (LANAP). Molecular biological determinations of bacterial markers through the polymerase chain reaction (real-time PCR) method with standard PET tests (species-specific DNA probes at a time) were used for the quantification of three of the most important periodontal pathogens (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Treponema denticola). Both nonsurgical periodontal therapies were proven effective in patients with chronic periodontal disease; however, LANAP was associated with a greater reduction in pocket depth and improved clinical outcomes, associated with a significant decrease in the amount of Porphyromonas gingivalis. The clinical results included a decrease in periodontal pocket depth, bleeding on probing, and dental plaque, with LANAP having better overall outcomes than SRP alone. The use of Nd:YAG lasers in LANAP therapy is a safe and effective procedure that is well accepted by patients.
... The production of intracellular ROS and the potential effect of NIR irradiation itself was negligible in the absence of N-CND@P25 NPs, regardless of the selected irradiation time (Figs. 3a-3b) [66]. In contrast, cells treated with N-CND@P25 NPs showed a significant increase of ROS production compared to non-treated cells, even without irradiation (Figs. ...
Cancer represents a major public health issue and a primary cause of death for the mankind and the search for alternative cancer treatments that assist or alleviate the drawbacks of current cancer therapies remains imperative. Nanocatalytic medicine represents a new discipline that aims at exploiting the unique response of heterogeneous catalysts exposed to unconventional conditions such as those encountered in the tumor microenvironment (TME). Photo-triggered cancer therapies using light-activable catalytic materiales can stimulate and activate multiple biological processes and represent a very promising field of study. Herein, we evaluate the use of carbon nanodots with different composition (CNDs) retrieved by laser pyrolysis as potential near-infrared (NIR) photosensitizers able to activate P25 semiconductor nanostructured photocatalysts. We describe the enhanced photocatalytic response towards glucose conversion and reactive oxygen species (ROS) generation upon irradiation with NIR-LEDs when CNDs doped with heteroatoms were tested. The most active photocatalysts were evaluated in the presence of cancer cells and revealed a promising photodynamic effect under NIR irradiation. This work represents one of the scarce examples of a conventional inorganic photocatalyst containing TiO2 that is translated into a biomedical application with a successful outcome.
... When investigating the effects of photobiomodulation, it is important to understand that it involves several parameters. Among these, wavelength is the most important, since it determines the light penetration depth into the tissues [42], which is also associated with the thermal effect caused by the light [43]. In general, a red-light laser presents a wavelength ranging from 620 to 740 nm, and an infrared-light laser has a wavelength ranging from 780 to 1000 nm [43]. ...
... Among these, wavelength is the most important, since it determines the light penetration depth into the tissues [42], which is also associated with the thermal effect caused by the light [43]. In general, a red-light laser presents a wavelength ranging from 620 to 740 nm, and an infrared-light laser has a wavelength ranging from 780 to 1000 nm [43]. Parameters such as energy density and duration of irradiation are also important because they determine the irradiation dose absorbed by the cells, directly affecting the expected biological effects [44]. ...
Unlabelled:
This review aimed to answer the following question "Does photobiomodulation treatment of the root surface decrease the occurrence of root resorption in reimplanted teeth?" Electronic searches were performed in the MEDLINE/PubMed, Cochrane Library, Scopus, Web of Science, Embase, and Grey Literature Report databases. Risk of bias was evaluated using SYRCLE Risk of Bias tool. The Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) tool was used to assess the certainty of evidence. In total, 6 studies were included. Five studies reported a reduced occurrence of root resorption in teeth that received photobiomodulation treatment of the root surface prior to replantation. Only 1 study reported contradictory results. The photobiomodulation parameters varied widely among studies. GRADE assessment showed a low certainty of evidence. It can be inferred that photobiomodulation treatment of the root surface prior to replantation of teeth can reduce the occurrence of root resorption. Nonetheless, further clinical studies are needed.
Trial registration:
PROSPERO Identifier: CRD42022349891.
... These findings show that the laser parameters utilized in this study had no significant effects on WS1 normal human cell death when administered alone without the presence of the ZnPcS 4 PS. These findings are supported by studies performed by Cios et al. (2021), which stated that red laser applications within the wavelength of 620 to 740 nm, without any additions of PS components, noted no difference in WS1 in-vitro-cultured biologic responses [48]. ...
... These findings show that the laser parameters utilized in this study had no significant effects on WS1 normal human cell death when administered alone without the presence of the ZnPcS 4 PS. These findings are supported by studies performed by Cios et al. (2021), which stated that red laser applications within the wavelength of 620 to 740 nm, without any additions of PS components, noted no difference in WS1 in-vitro-cultured biologic responses [48]. ...
The most prevalent type of gynecological malignancy globally is cervical cancer (CC). Complicated by tumor resistance and metastasis, it remains the leading cause of cancer deaths in women in South Africa. Early CC is managed by hysterectomy, chemotherapy, radiation, and more recently, immunotherapy. Although these treatments provide clinical benefits, many patients experience adverse effects and secondary CC spread. To minimize this, novel and innovative treatment methods need to be investigated. Photodynamic therapy (PDT) is an advantageous treatment modality that is non-invasive, with limited side effects. The Cannabis sativa L. plant isolate, cannabidiol (CBD), has anti-cancer effects, which inhibit tumor growth and spread. This study investigated the cytotoxic combinative effect of PDT and CBD on CC HeLa cells. The effects were assessed by exposing in vitro HeLa CC-cultured cells to varying doses of ZnPcS4 photosensitizer (PS) PDT and CBD, with a fluency of 10 J/cm2 and 673 nm irradiation. HeLa CC cells, which received the predetermined lowest dose concentrations (ICD50) of 0.125 µM ZnPcS4 PS plus 0.5 µM CBD to yield 50% cytotoxicity post-laser irradiation, reported highly significant and advantageous forms of cell death. Flow cytometry cell death pathway quantitative analysis showed that only 13% of HeLa cells were found to be viable, 7% were in early apoptosis and 64% were in late favorable forms of apoptotic cell death, with a minor 16% of necrosis post-PDT. Findings suggest that this combined treatment approach can possibly induce primary cellular destruction, as well as limit CC metastatic spread, and so warrants further investigation.
... The light source plays a critical role in providing the required energy for light emission by the target molecule excited in the sample kept within the lateral flow immunoassay test strip. Common light sources are light-emitting diodes [18,[45][46][47] and laser diodes [48,49]. A light-emitting diode (LED) is a solidstate, stable, and compact source producing light when a current is applied. ...
Fluorescence-based optical test strip readers are used to detect and quantify fluorescent signals from immunoassay test strips in medicine, especially for point-of-care applications. The design of optical systems including light sources and detection systems in these devices is not only indispensable but also the most critical part for specific detection applications. This study aims to provide detailed information about fluorescence-based optical test strip readers, existing and emerging technologies, and their contributions to the design of the device. The most commonly used technologies of light sources and detection systems have been discussed and compared for the ideal design. Arc and Xenon lamps may not be appropriate for portable and low-cost devices as they are larger and more costly when compared to LEDs and laser diodes. Photodiodes and CMOS detectors can be used for the design of low-cost, portable fluorescence-based optical test strip readers as they are cheaper and smaller in size when compared to CCDs and PMTs. Both light source and detector should be chosen according to the application priorities and spectral characteristics of the fluorescent molecule by integrating them with proper optical elements like filters, mirrors, etc. This study contributes to the people who are interested in the design of fluorescence-based optical test strip readers as it serves as a guideline for the optical test strip reader systems.
... Based on observations made using the paint experiments, we can hypothesise that the high peak SD values and strong gradients observed using red laser illumination were due to the combined reflection, refraction, and scattering of light in the seed-air interface. By contrast, the scattering produced by water is less intense in IR light, with this wavelength absorbed in a higher proportion compared to that with the red laser, as demonstrated in earlier studies [45,46]. The scattering of the IR laser is combined with the scattering produced by the return of the light from the tissue, which is also affected by pigments. ...
Dynamic laser speckle (DLS) analysis is a very sensitive technique to measure biological activity within samples. In agriculture, the technique is applied to monitor seed germination, but external light, water content, and pigments affect the measurements. DLS systems use visible light sources, typically red lasers, which may exacerbate their influences. The main objective of this work is to assess whether infrared (IR) lasers improve the robustness of DLS measurements in seed germination applications. We develop a system where DLS analysis can be performed simultaneously on visible and IR light. Using the system, we quantify how the DLS signal is affected by pigments and scattering. The results show that the use of IR light reduces the variability of the measurements acquired. DLS systems based on IR light appear to be less sensitive to pigments, and the greater penetration of IR light into samples, which is due to reduced scattering, may contribute to the signal collected being correlated to relevant biological processes within the inner tissue. Additionally, water activity provides less influence on the DLS signal when an IR laser is used. These findings support the wider use of IR lasers in DLS-based instruments for applications in biological samples.
... Additionally, in the field of medical devices and research, significant work has been done in recent years to develop OLED systems based on ITO and improve luminance and its impact on the human body and health [22]. The healing phenomenon occurs at the sites via a photobiological reaction depending on the depth through the human body in the spectrum between 300 nm and 830 nm [23]. An OLED device in photomedicine is engaged during mitochondrial ATP production at specific wavelength bands of PBM. ...
This study investigated the electro-optic properties of organic light-emitting diode (OLED) devices with the addition of an interlayer. A device with the perfluorododecyl-1H,1H,2H,2H-triethoxysilane–perfluorotetradecyl 1H,1H,2H,2H-triethoxysilane mixture (hybrid solution) membrane applied to the hole injection layer (HIL) using a self-assembled monolayer (SAM), along with N,N’-Bis (naphtha-len-1-yl)-N,N’-bis(phenyl)-2,2’-dimethylbenzidine (α-NPD) applied to the hole transport layer (HTL), was fabricated and subsequently assessed. Compared to the device without an HIL, the device with HIL using SAM showed a luminance of 1630.16 (Cd/m2) at the maximum cut-off voltage of 11 V, and the efficiency was increased to ≥200% from the initial turn-on voltage of 3 V to the maximum cut-off voltage. These results suggest that adding an interlayer and the consequent carrier ladder effect led to more efficient injection and transport, possibly lowering the hole injection barrier and allowing excellent power efficiency.
