On-line laser radiation controlled to the removal of adhesive on teeth after bracket debonding.

Background And Aims: After bracket debonding a correct removal of the adhesive from tooth surfaces without causing any iatrogenic damage to the enamel is needed. However, conventional techniques do not allow a selective removal process. The present article focuses on the removal of adhesive on teeth after bracket debonding by using laser radiation at 355 nm (third harmonic wavelength of a Q-switched Nd:YAG).

Circularly polarized laser emission induced in isotropic and achiral dye systems.

The production of efficient, tunable, and switchable circularly polarized laser emission would have far reaching implications in optical communications or biophotonics. In this work, it is demonstrated the direct generation of circularly polarized (CP) laser emission in achiral and isotropic dye laser systems without the use of extracavity polarizing elements, and without resorting to chiral dyes, chiral liquid crystal matrices, or interferometric methods. The origin of this ellipticity arises from the dynamic birefringence induced by the strong and polarized laser pumping and the subsequent orientation anisotropy of the excited molecular dipoles.

Mechanically tunable organic vertical-cavity surface emitting lasers (VCSELs) for highly sensitive stress probing in dual-modes.

Herein, we report a straight forward stress probing method based on mechanically tunable organic VCSELs via dual detecting-modes. By designing the active layer thickness, uploaded stress was measured simultaneously by the laser wavelength and mode separations, facilitating highly sensitive stress detection in broad ranges. Single-mode laser emission with low threshold and narrow line-width was characterized, which could be tuned continuously within 8 nm.

A borane laser.

Emission from electronically excited species forms the basis for an important class of light sources-lasers. So far, commercially available solution-processed blue-emitting laser materials are based on organic compounds or semiconductor nanocrystals that have significant limitations: either low solubility, low chemical- and/or photo-stability and/or uncompetitive prices. Here we report a novel and competitive alternative to these existing laser materials that is based on boron hydrides, inorganic cluster compounds with a rich and diverse chemistry.

Straightforward synthetic protocol for the introduction of stabilized C nucleophiles in the BODIPY core for advanced sensing and photonic applications.

A straightforward synthetic protocol to directly incorporate stabilized 1,3-dicarbonyl C nucleophiles to the meso position of BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) is reported. Soft nucleophiles generated by deprotonation of 1,3-dicarbonyl derivatives smoothly displace the 8-methylthio group from 8-(methylthio)BODIPY analogues in the presence of Cu(I) thiophenecarboxylate in stoichiometric amounts at room temperature. Seven highly fluorescent new derivatives are prepared with varying yields (20-92%) in short reaction times (5-30 min).

First highly efficient and photostable E and C derivatives of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) as dye lasers in the liquid phase, thin films, and solid-state rods.

A new library of E- and C-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) derivatives has been synthesized through a straightforward protocol from commercially available BODIPY complexes, and a systematic study of the photophysical properties and laser behavior related to the electronic properties of the B-substituent group (alkynyl, cyano, vinyl, aryl, and alkyl) has been carried out. The replacement of fluorine atoms by electron-withdrawing groups enhances the fluorescence response of the dye, whereas electron-donor groups diminish the fluorescence efficiency. As a consequence, these compounds exhibit enhanced laser action with respect to their parent dyes, both in liquid solution and in the solid phase, with lasing efficiencies under transversal pumping up to 73 % in liquid solution and 53 % in a solid matrix.

Blue-to-orange color-tunable laser emission from tailored boron-dipyrromethene dyes.

A series of meso-substituted boron-bipyrromethene (BODIPY) dyes are synthesized and their laser and photophysical properties systematically studied. Laser emission covering a wide visible spectral region (from blue to orange) is obtained by just changing the electron donor character of the heteroatom at position 8. The additional presence of methyl groups at positions 3 and 5 results in dyes with a photostability similar to that of the unsubstituted dye but with much improved efficiency.

Photophysical and laser properties of cassettes based on a BODIPY and rhodamine pair.

This work deals with the synthesis and the photophysical and laser properties of new BODIPY-rhodamine cassettes. These dyads differ in their rigid and conjugated spacer group (phenyl or acetylenephenyl) and in their linking positions (meta or para). The photophysical properties of these cassettes are controlled by the formation/opening of the spirolactone ring, which, in turn, switches off/on an energy-transfer process between the chromophores.

Reaction of amines with 8-methylthioBODIPY: dramatic optical and laser response to amine substitution.

A thorough study of the photophysical and laser properties of 8-aminoboron dipyrromethene dyes was undertaken to determine the role of amine substitution and spatial disposition on the properties of the dyes. It was found that the fluorescent and laser response varied significantly. Although primary amines give rise to highly fluorescent products at the blue edge of the visible region, secondary amines yield nonfluorescent analogues in polar media.

Synthesis and optical and redox properties of symmetric and asymmetric BODIPYs.

Herein, we present the synthetic route and the photophysical, electrochemical as well as laser properties of novel red-emitting boron-dipyrromethenes (BODIPYs) bearing arylethyne moieties. Such functionality is added along the main axis of the chromophore leading to single- and double-substituted derivatives. The relationship between the dye structure and the lasing properties is studied in detail with the help of the photophysical and electrochemical properties as well as quantum mechanical simulations.

Click assembly of dye-functionalized octasilsesquioxanes for highly efficient and photostable photonic systems.

New hybrid organic-inorganic dyes based on an azide-functionalized cubic octasilsesquioxane (POSS) as the inorganic part and a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BDP) chromophore as the organic component have been synthesized by copper(I)-catalyzed 1,3-dipolar cycloaddition of azides to alkynes. We have studied the effects of the linkage group of BDP to the POSS unit and the degree of functionalization of this inorganic core on the ensuing optical properties by comparison with model dyes. The high fluorescence of the BDP dye is preserved in spite of the linked chain at its meso position, even after attaching one BDP moiety to the POSS core.

Unprecedented laser action from energy transfer in multichromophoric BODIPY cassettes.

A cassette molecule, featuring direct integration of two donor BODIPY units to one acceptor BODIPY unit, was conveniently developed as the first highly "through-bond energy transfer" (TBET) laser dye. This multicolor absorbing dye exhibited highly efficient and photostable laser action under drastic pumping conditions.

Development of excellent long-wavelength BODIPY laser dyes with a strategy that combines extending π-conjugation and tuning ICT effect.

By comparison and combination of two strategies, extending π-conjugation and tuning Intramolecular Charge Transfer (ICT) effect, new long-wavelength BODIPY dyes have been efficiently synthesized. The new chromophores exhibit good optical properties: high fluorescence quantum yields, exceptionally large molar extinction coefficients, narrow red-emission bands, and relatively large Stokes shifts etc., in polar or apolar solvents.

New 8-amino-BODIPY derivatives: surpassing laser dyes at blue-edge wavelengths.

The development of highly efficient and stable blue-emitting dyes to overcome some of the most important shortcomings of available chromophores is of great technological importance for modern optical, analytical, electronic, and biological applications. Here, we report the design, synthesis and characterization of new tailor-made BODIPY dyes with efficient absorption and emission in the blue spectral region. The major challenge is the effective management of the electron-donor strength of the substitution pattern, in order to modulate the emission of these novel dyes over a wide spectral range (430-500 nm).

Difluoro-boron-triaza-anthracene: a laser dye in the blue region. Theoretical simulation of alternative difluoro-boron-diaza-aromatic systems.

The synthesis, photophysical and laser properties of a difluoro-boron-triaza-anthracene (BTAA) compound are analyzed in the present paper. The molecular structure of this dye is an anthracene-like core with N atoms at 4a, 9 and 10a positions where two of them (4a and 10a) are linked through a BF(2)-bridge group. This structure is reminiscent of aza-BODIPY dye with an s-indacene core, BODIPY being one of the most commonly used laser dye family in the Vis region.

Influence of the light source and bleaching gel on the efficacy of the tooth whitening process.

Objective: To examine the whitening efficacy of three whitening agents in combination with six different photoactivation systems.

Background: Bleaching techniques have achieved significant advances using photoactivation with coherent or incoherent radiation sources.

Methods: Quick White, Ena White Power, and Opalescence Endo bleaching agents, all containing 35% hydrogen peroxide, were stimulated with halogen lamp, light-emitting diode (LED), low-power diode laser, and neodymium: yttrium-aluminum-garnet (Nd:YAG), second harmonic of Nd:YAG, and Er:YAG lasers.

Controlling optical properties and function of BODIPY by using asymmetric substitution effects.

Asymmetrically substituted BODIPY analogues of the dye PM567 have been synthesised from 2-acylpyrroles and pyrroles that bear indene, fluorene or difluorene units. The type of linkage between the fluorene and the BODIPY core plays an important role in the photophysics of the BODIPY chromophore. Indeed, an aliphatic bridge gives rise to an energy-transfer process between the chromophores, whereas a vinyl spacer allows an electronic interaction between them, leading to a large red shift of the spectral bands.

Skin laser treatments enhancing transdermal delivery of ALA.

Drug delivery across skin has been limited due to barrier properties of the skin, especially those of the stratum corneum (SC). Use of the laser radiation has been suggested for the controlled removal of the SC. The purpose of this study was to study in vitro the influence of infrared radiation from the erbium:yttrium-aluminum-garnet (Er:YAG) laser (λ = 2940  nm), and visible from the 2nd harmonic of a neodymium:yttrium-aluminum-garnet (Nd:YAG) laser (λ = 532  nm) on transdermal delivery of 5-aminolevulinic acid (ALA).

8-PropargylaminoBODIPY: unprecedented blue-emitting pyrromethene dye. Synthesis, photophysics and laser properties.

Highly emitting 8-propargylaminoBODIPY (8-PAB) 2 was prepared in 94% yield. Unlike any other BODIPY structure hitherto described in the literature, 2 displays efficient emission in the blue region of the visible spectrum with a fluorescence quantum yield up to 0.94 and high laser efficiency (35%) at 483 nm.

Conventional unidirectional laser action enhanced by dye confined in nanoparticle scatters.

The synthesis, structural characterization, and lasing properties of new dye-sensitized organic scattering gain medium based on Rhodamine 6G (Rh6G) confined in polymeric nanoparticles are reported. We have demonstrated coherent laser action from amplifying random media using dye confined into polymeric nanoparticles as scattering centers and gain media. Lasing efficiency and photostability were significantly enhanced by nonresonant feedback of the emission by multiple scattering.

In vitro and in vivo laser treatments of tattoos: high efficiency and low fluences.

Objective: To analyze the absorption of tattoo inks related to their in vivo and in vitro behavior under laser irradiation to improve laser-assisted tattoo removal.

Design: The absorption of 21 tattoo inks in a wavelength range from 300 to 800 nm was characterized by reflection spectroscopy from samples consisting of inks mixed in gelatin. Tattoo inks were removed in vitro using pulsed laser radiation with different variables, and morphologic analysis of the irradiated areas was performed.

Efficient red-edge materials photosensitized by Rhodamine 640.

We report on tunable, highly efficient and photostable solid-state dye laser emitting around 640 nm based on Rhodamine 640 incorporated into homopolymers, linear and cross-linked copolymers, and silicon-modified organic matrices. The effect on the lasing properties of both dye concentration and environmental conditions was analyzed. Under transversal pumping at 532 nm with 5.

Evaluation of the effects of Er:YAG and Nd:YAG lasers and ultrasonic instrumentation on root surfaces.

Objective: Evaluate the effects of Er:YAG and Nd:YAG lasers on the morphology and chemical composition of root surfaces and compare them with those produced by using ultrasonic instrumentation (US).

Background Data: The benefits of the use of Er:YAG and Nd:YAG lasers as an adjunct to conventional periodontal therapy have not yet been determined.

Materials And Methods: The radicular surfaces of 18 extracted human multi-radicular teeth were treated for 1 min on the right side of the root either with laser (Er:YAG, 2940 nm, 10 Hz, output 80 mJ/pulse, 100 mJ/pulse, and 120 mJ/pulse, 250 mus pulse length, spot size 0.

Laser treatments on skin enhancing and controlling transdermal delivery of 5-fluorouracil.

Background And Objective: Laser ablation of stratum corneum (SC) enhances transdermal delivery of hydrophilic drugs. The influence of the infrared (IR) (lambda = 1,064 nm), visible (lambda = 532 nm), and ultraviolet (UV) (lambda = 355 nm) radiations of a Nd:YAG laser on transdermal delivery of 5-Fluorouracil (5-Fu) across skin was studied in vitro.

Materials And Methods: Pinna skin of the inner side of rabbit ear, was used for the skin permeation.

Synthesis, photophysical properties, and laser behavior of 3-amino and 3-acetamido BODIPY dyes.

The asymmetrically substituted BODIPY dyes 9a and 9b have been synthesized through a key redox step involving the alpha-nitroso derivative of the starting pyrrol. Both dyes emit fluorescence with quantum yields of ca. 0.