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Biomedical Optics Express May 2023Picosecond Nd:YAG lasers using diffractive optical elements (DOE) and micro-lens arrays (MLA) have widely been used in dermatology for the treatment of pigmented lesions...
Picosecond Nd:YAG lasers using diffractive optical elements (DOE) and micro-lens arrays (MLA) have widely been used in dermatology for the treatment of pigmented lesions and skin rejuvenation. This study designed and developed a new optical element of diffractive micro-lens array (DLA) by combing the features of DOE and MLA in order to achieve uniform and selective laser treatment. Both optical simulation and beam profile measurement demonstrated that DLA created a square macro-beam consisting of multiple micro-beams in a uniform distribution. Histological analysis confirmed that the DLA-assisted laser treatment generated micro-injuries at various skin depths from the epidermal layer to the deep dermal layer (up to 1200 µm) by adjusting the focal depths while DOE showed shallow penetration depths and MLA created non-uniform micro-injury zones. The DLA-assisted picosecond Nd:YAG laser irradiation can provide a potential benefit for pigment removal and skin rejuvenation via uniform and selective laser treatment.
PubMed: 37206149
DOI: 10.1364/BOE.488024 -
Lasers in Surgery and Medicine Jan 2021Laser-pumped lasers enable driving a secondary wavelength through pumping with a primary device. Here we investigate the first 730 nm laser-pumped laser for efficacy...
BACKGROUND AND OBJECTIVES
Laser-pumped lasers enable driving a secondary wavelength through pumping with a primary device. Here we investigate the first 730 nm laser-pumped laser for efficacy in tattoo removal.
STUDY DESIGN/MATERIALS AND METHODS
Fifteen subjects with 20 tattoos were enrolled to investigate the effect of a new 730 nm, titanium-sapphire laser-pumped laser at removing decorative tattoos. A total of four treatments were administered and photographic improvement of pre- and post-treatment cross-polarized digital images was evaluated by four blinded physician observers using an 11-point scale.
RESULTS
Blinded assessment of pre- and post-treatment images found 70%, 77%, 83%, 83%, 26%, and 8% clearance from baseline images for black, green, blue, purple, red and yellow pigments, respectively. Side effects were limited to pinpoint bleeding and erythema immediately after treatment and some crusting and scale up to 1-2 weeks following treatment, and a localized allergic reaction in a single subject. There was no scarring or pigmentary alteration visible in any follow-up images.
CONCLUSION
The new 730 nm, picosecond-domain, titanium-sapphire, laser-pumped laser is safe and effective for removing multicolored tattoos. Green, blue, and purple pigments cleared the most as expected, but black ink cleared more completely than was predicted. Lasers Surg. Med. © 2020 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals LLC.
Topics: Humans; Laser Therapy; Lasers; Photography; Pigmentation Disorders; Tattooing
PubMed: 32212171
DOI: 10.1002/lsm.23237 -
Journal of Lasers in Medical Sciences 2022The aging process in the skin naturally happens over time, affected by several factors, of which ultraviolet irradiation is a major factor, and this leads to the...
The aging process in the skin naturally happens over time, affected by several factors, of which ultraviolet irradiation is a major factor, and this leads to the appearance of wrinkles, pigmentations, and textural irregularities. Lasers for facial rejuvenation are very popular in Asian patients, but melanin rick skin types like Asians are more susceptible to pigmentary alterations. Most Indonesians have brown skin, and just a few have light skin. The purpose of this study was to know the efficacy and safety of the picosecond 755 nm laser in facial rejuvenation in Indonesian skin. This is an analysis of 20 healthy patients with Fitzpatrick skin type III-V with facial photoaging from 36 to 55 years. Examinations were evaluated before therapy and 4 weeks after the second therapy. The front and side of both cheeks were photographed and analyzed by using VISIA. Clinical improvement was categorized as excellent-mild. The patients were also asked and examined about the presence of adverse events. The patients were predominantly female with an average age of 44 years. Sixty percent of the patients had a good improvement and 40% of the patients had a moderate improvement. The VISIA analysis showed a significant improvement in wrinkles, pigments, and textures ( < 0.001). Only mild anticipated adverse events were observed, and there was no post-inflammatory hyperpigmentation or hypopigmentation. the picosecond 755 nm laser is effective and safe for facial rejuvenation in the skin of Indonesian patients without significant adverse events.
PubMed: 36743150
DOI: 10.34172/jlms.2022.45 -
Chembiochem : a European Journal of... Aug 2020Charge transfer has proven to be an important mechanism in DNA photochemistry. In particular, guanine (dG) plays a major role as an electron donor, but the photophysical...
Charge transfer has proven to be an important mechanism in DNA photochemistry. In particular, guanine (dG) plays a major role as an electron donor, but the photophysical dynamics of dG-containing charge-transfer states have not been extensively investigated so far. Here, we use UV pump (266 nm) and picosecond IR probe (∼5-7 μm) spectroscopy to study ultrafast dynamics in dG-containing short oligonucleotides as a function of sequence and length. For the pure purine oligomers, we observed lifetimes for the charge-transfer states of the order of several hundreds of picoseconds, regardless of the oligonucleotide length. In contrast, pyrimidine-containing dinucleotides d(GT) and d(GC) show much faster relaxation dynamics in the 10 to 30 ps range. In all studied nucleotides, the charge-transfer states are formed with an efficiency of the order of ∼50 %. These photophysical characteristics will lead to an improved understanding of DNA damage and repair processes.
Topics: Base Sequence; DNA; Electron Transport; Guanosine; Oligonucleotides; Photochemical Processes; Ultraviolet Rays
PubMed: 32239789
DOI: 10.1002/cbic.202000103 -
Optics Express Nov 2023The precise temporal characterization of laser pulses is crucial for ultrashort applications in biology, chemistry, and physics. Especially in femto- and attosecond...
The precise temporal characterization of laser pulses is crucial for ultrashort applications in biology, chemistry, and physics. Especially in femto- and attosecond science, diverse laser pulse sources in different spectral regimes from the visible to the infrared as well as pulse durations ranging from picoseconds to few femtoseconds are employed. In this article, we present a versatile temporal-characterization apparatus that can access these different temporal and spectral regions in a dispersion-free manner and without phase-matching constraints. The design combines transient-grating and surface third-harmonic-generation frequency-resolved optical gating in one device with optimized alignment capabilities based on a noncollinear geometry.
PubMed: 38041296
DOI: 10.1364/OE.503731 -
Optics Express Feb 2020We report a high-average-power mid-infrared picosecond (ps) optical parametric oscillator (OPO) based on orientation-patterned gallium arsenide (OP-GaAs), with wide...
We report a high-average-power mid-infrared picosecond (ps) optical parametric oscillator (OPO) based on orientation-patterned gallium arsenide (OP-GaAs), with wide wavelength tunability. The OP-GaAs OPO is synchronously pumped by a thulium-doped-fiber (TDF) master oscillator power amplifier (MOPA), seeded by a gain-switched laser diode. At a pump power of 35.3 W and a repetition rate of 100 MHz, a maximum OPO total average output power of 9.7 W (signal 5.7 W (0.60 kW peak power), idler 4.0 W (0.42 kW peak power)) is obtained at signal and idler wavelengths of 3093 nm and 5598 nm, and a thermally induced power roll-off is observed. To mitigate the thermal effects, an optical chopper is placed before the OPO to provide burst mode operation and a reduced thermal load. We achieved a linear growth in OPO output power over the full range of available pump powers in this instance confirming thermal effects as the origin of the roll-off observed under continuous pumping. We estimate the maximum peak powers of the signal and idler are estimated to be over 0.79 kW and 0.58 kW, respectively in this instance. A wide mid-infrared wavelength tuning range of 2895-3342 nm (signal) and 4935-6389 nm (idler) is demonstrated.
PubMed: 32121789
DOI: 10.1364/OE.380189 -
Scientific Reports Mar 2022The tattoos removal has become an issue upon spread of the tattooing practice worldwide and hindsight regrets. Lasers are typically used for the purpose, though some...
The tattoos removal has become an issue upon spread of the tattooing practice worldwide and hindsight regrets. Lasers are typically used for the purpose, though some colours such as green are considered "recalcitrant" to the treatment. In the current investigation, we aim at determining the efficacy of removal of a green ink water dispersion, using 5 laser treatments: Nd:YAG nano- and picosecond lasers in normal and array mode and Ruby nanosecond laser, keeping the total irradiated energy constant. The UV-Vis spectroscopy of the treated samples indicate that Nd:YAG picosecond laser is most effective, and the Ruby nanosecond laser is the least efficient. Fragment compounds generated from the pigment and siloxanes are common to all treatments, whereas hydrocarbon emerge by a larger amount upon Nd:YAG nanosecond treatment. Fibres are formed upon picosecond treatments and when operating in array mode, and lamellae are achieved by Ruby nanosecond laser treatment. Residual particles suspensions are very heterogeneous upon nanosecond treatments.
Topics: Ink; Laser Therapy; Lasers, Solid-State; Pigmentation; Tattooing
PubMed: 35246552
DOI: 10.1038/s41598-022-07021-w -
Lasers in Surgery and Medicine Jan 2022A 730 nm picosecond-domain laser was developed to improve the clearance of pigmented lesion and reduce adverse events. This study assessed the safety and efficacy of...
OBJECTIVE
A 730 nm picosecond-domain laser was developed to improve the clearance of pigmented lesion and reduce adverse events. This study assessed the safety and efficacy of this system for the clearance of lentigines and explores how the short picosecond pulses interact with tissue via histology.
STUDY DESIGN AND METHODS
Twenty subjects with Fitzpatrick skin types II-IV were enrolled in this prospective, IRB-approved study. Four treatments were administered using a 730 nm picosecond-domain laser. Pre- and posttreatment photos were assessed by blinded reviewers at 4- and 12-week follow-up visits, using a 5-point clearance scale. Subject satisfaction was measured using a 5-point scale. Investigator Global Improvement Score (IGIS) was performed at the 4- and 12-week follow-up visits, using an 11-point clearance scale. Subject pain level was measured using an 11-point scale (no pain [0], extreme pain [10]). Histology of 730 and 532 nm picosecond pulses was compared with 755 and 532 nm nanosecond pulses.
RESULTS
Sixteen subjects with a total of 118 discontinuous treatment areas, each comprised of 1-20 lesions, completed all study visits. Thirty body regions were studied, including arms (6), hands (16), scalp (1), forehead (2), face (3), and back (2). Spot sizes ranging from 2 to 5 mm diameters were used with fluences ranging from 0.8 to 4.0 J/cm . Mean pain score was 3.6 of 10 for all four treatments. Ninety-nine percent of randomly paired 4-week posttreatment images and 100% of 12-week posttreatment images were correctly identified from their respective baseline images by three blinded reviewers. Mean IGIS demonstrated scores of 6.7 and 7.0 at 4- and 12-week follow-up visits, respectively. At the 4- and 12-week follow-up visits, 76% and 73% of subjects, respectively, were satisfied to highly satisfied. The mean clearance score for all 118 treatment areas was 3 of 4 in follow-up visits. At 12-week follow-up, 36% of 118 treatment areas had a clearance score of 4, and 38% had a clearance score of 3. Post treatment, there was typical erythema, edema, dryness, crusting, and itching but negligible purpura, no pinpoint bleeding, blistering or scarring, and no significant hyperpigmentation or hypopigmentation. Histology showed diffuse, focal epidermal vacuolization ~5-10 µm in diameter and mild extravasation of erythrocytes with 730 nm picosecond pulses, while diffuse epidermal vacuolization was observed with coalescence of vacuoles (~20-100 µm), junctional clefting and mild extravasation of erythrocytes with 755 nm nanosecond pulses. Picosecond pulses of the wavelength of 532 nm produced diffuse, focal epidermal vacuolization and larger dermal vacuoles to depths of 500 µm, while 532 nm nanosecond pulses produced diffuse epidermal vacuolization with coalescence of vacuoles and marked dermal hemorrhage.
CONCLUSION
This study demonstrated the potential of a new 730 nm picosecond-domain laser for the clearance of lentigines. The results showed good clearance with no adverse events and good subject satisfaction in patients with skin type II-III. Additional studies need to be conducted on darker skin types. The histopathologic findings demonstrate that the picosecond 730 nm laser produces excellent selectivity for pigment with minimal disruption of the dermal-epidermal junction and may therefore reduce healing times and the risk of adverse events.
Topics: Aluminum Oxide; Humans; Lasers, Solid-State; Lentigo; Prospective Studies; Titanium; Treatment Outcome
PubMed: 34402537
DOI: 10.1002/lsm.23450 -
Pharmaceutics Mar 2022Remote triggering of contents release with micron spatial and sub-second temporal resolution has been a long-time goal of medical and technical applications of... (Review)
Review
Remote triggering of contents release with micron spatial and sub-second temporal resolution has been a long-time goal of medical and technical applications of liposomes. Liposomes can sequester a variety of bioactive water-soluble ions, ligands and enzymes, and oligonucleotides. The bilayer that separates the liposome interior from the exterior solution provides a physical barrier to contents release and degradation. Tethering plasmon-resonant, hollow gold nanoshells to the liposomes, or growing gold nanoparticles directly on the liposome exterior, allows liposome contents to be released by nanosecond or shorter pulses of near-infrared light (NIR). Gold nanoshells or nanoparticles strongly adsorb NIR light; cells, tissues, and physiological media are transparent to NIR, allowing penetration depths of millimeters to centimeters. Nano to picosecond pulses of NIR light rapidly heat the gold nanoshells, inducing the formation of vapor nanobubbles, similar to cavitation bubbles. The collapse of the nanobubbles generates mechanical forces that rupture bilayer membranes to rapidly release liposome contents at the preferred location and time. Here, we review the syntheses, characterization, and applications of liposomes coupled to plasmon-resonant gold nanostructures for delivering a variety of biologically important contents in vitro and in vivo with sub-micron spatial control and sub-second temporal control.
PubMed: 35456535
DOI: 10.3390/pharmaceutics14040701 -
Nature Communications Feb 2023Interfaces in heavy metal (HM) - antiferromagnetic insulator (AFI) heterostructures have recently become highly investigated and debated systems in the effort to create...
Interfaces in heavy metal (HM) - antiferromagnetic insulator (AFI) heterostructures have recently become highly investigated and debated systems in the effort to create spintronic devices that function at terahertz frequencies. Such heterostructures have great technological potential because AFIs can generate sub-picosecond spin currents which the HMs can convert into charge signals. In this work we demonstrate an optically induced picosecond spin transfer at the interface between AFIs and Pt using time-domain THz emission spectroscopy. We select two antiferromagnets in the same family of fluoride cubic perovskites, KCoF and KNiF, whose magnon frequencies at the centre of the Brillouin zone differ by an order of magnitude. By studying their behaviour with temperature, we correlate changes in the spin transfer efficiency across the interface to the opening of a gap in the magnon density of states below the Néel temperature. Our observations are reproduced in a model based on the spin exchange between the localized electrons in the antiferromagnet and the free electrons in Pt. Through this comparative study of selected materials, we are able to shine light on the microscopy of spin transfer at picosecond timescales between antiferromagnets and heavy metals and identify a key figure of merit for its efficiency: the magnon gap. Our results are important for progressing in the fundamental understanding of the highly discussed physics of the HM/AFI interfaces, which is the necessary cornerstone for the designing of femtosecond antiferromagnetic spintronics devices with optimized characteristics.
PubMed: 36725847
DOI: 10.1038/s41467-023-36166-z