On the mechanism of visible-light sensitized photosulfoxidation of toluidine blue O.

We report on the formation of toluidine blue O (TBO) sulfoxide by a self-sensitized photooxidation of TBO. Here, the photosulfoxidation process was studied by mass spectrometry (MS) and discussed in the context of photodemethylation processes which both contribute to TBO consumption over time. Analysis of solvent effects with D2O, H2O, and CH3CN along with product yields and MS fragmentation patterns provided mechanistic insight into TBO sulfoxide's formation. The formation of TBO sulfoxide is minor and detectable up to 12% after irradiation of 3 h. The photosulfoxidation process is dependent on oxygen wherein instead of a type II (singlet oxygen, 1O2) reaction, a type I reaction involving TBO to reach the TBO sulfoxide is consistent with the results. Density functional theory results point to the formation of the TBO sulfoxide by the oxidation of TBO via transiently formed peroxyl radical or thiadioxirane intermediates. We discover that the TBO photosulfoxidation arises competitively with TBO photodemethylation with the latter leading to formaldehyde formation.

Self-Sensitized and Reversible O2 Reactivity with Bisphenalenyls for Simple, Tunable, and Multicycle Colorimetric Oxygen-Sensing Films.

Monitoring the levels of molecular oxygen (O2) is critical for numerous applications, but there is still a long-standing challenge to develop robust and cost-effective colorimetric sensors that enable detection by changes in color. Current technologies employ chromophores that require additional additives, which inherently increase the cost and complexity. Here, we report that bisphenalenyls (PQPLs) function as the single active component for colorimetric O2 sensing through their quantitative conversion into aromatic endoperoxides (EPOs). PQPLs display self-sensitizing reactivity: they are capable of generating singlet oxygen and binding it without the need for external photosensitizers. The rates of PQPL photooxygenation depend on the electron-donating ability of substituents, which highlights a simple strategy for tuning O2 sensitivity. EPOs are stable under ambient conditions but can be thermally stimulated to convert back to PQPLs and concomitantly release O2. Polymer-supported (PTMSP) films of PQPLs (2 wt %) reproduce these reactivity trends with a rapid red-to-colorless transition that is visible to the naked eye within 1 h of exposure and show a very low limit of detection (<5 ppm O2). Films are chemically and thermally robust and maintain up to >99% of their original colorimetric response when reused and subjected to multiple cycles of photooxygenation and O2 release. The simplicity and solution processability of these materials highlight their potential as "intelligent" inks for printable colorimetric sensors.

NIR-activated self-sensitized polymeric micelles for enhanced cancer chemo-photothermal therapy.

NIR-activated therapies based on light-responsive drug delivery systems are emerging as a remote-controlled method for cancer precise therapy. In this work, fluorescent dye indocyanine green (ICG)-conjugated and bioactive compound gambogic acid (GA)-loaded polymeric micelles (GA@PEG-TK-ICG PMs) were smoothly fabricated via the self-assembly of the reactive oxygen species (ROS)-responsive thioketal (TK)-linked amphiphilic polymer poly(ethyleneglycol)-thioketal-(indocyanine green) (PEG-TK-ICG). The resultant micelles demonstrated increased resistance to photobleaching, enhanced photothermal conversion efficiency, NIR-controlled drug release behavior, preferable biocompatibility, and excellent tumor accumulation performance. Moreover, upon an 808 nm laser irradiation, the micellar photoactive chromophore ICG converted the absorbed optical energy to both hyperthermia for photothermal therapy (PTT) and ROS as the feedback trigger to the micelles for the tumor-specific release of GA, which could serve as not only a chemotherapeutic drug to directly kill tumor cells but also a heat shock protein 90 (HSP90) inhibitor to realize the photothermal sensitization. As a result, an extremely high tumor inhibition rate (97.9%) of mouse 4 T1 breast cancer models was achieved with negligible side effects after the chemo-photothermal synergistic therapy. This NIR-activated nanosystem with photothermal self-sensitization function may provide a feasible option for the effective treatment of aggressive breast cancers.

Significant role of iron on the fate and photodegradation of enrofloxacin.

Enrofloxacin (ENR) belongs to the fluoroquinolone (FQ) antibiotics family, which are contaminants of emerging concern frequently found in effluents. Although many works studying photo-Fenton process for FQ degradation have been reported, there are no reports analysing in deep the effect of iron complexation, as well as other metals, towards FQs' photolysis, which, evidently, also contributes in the overall degradation of the pollutant. Therefore, in this work, we report a comparative study between the photochemical fate of ENR and its complex with Fe(III) under simulated sunlight irradiation. In addition, the effect of dissolved oxygen, self-sensitization process, and H2O2 addition on the studied photochemical systems are also investigated. Results indicate that, for free and iron-complexed ENR, singlet oxygen (1O2) is generated from the interaction of its triplet state with ground state oxygen. Half-life time (t1/2) of ENR under sun simulated conditions is estimated to be around 22 min, while complexation with iron enhances its photostability, leading to a t1/2 of 2.1 h. Such finding indicates that at least the presence of iron, might notably increase the residence time of these pollutants in the environment. Eventually, only with the addition of H2O2, the FQ-iron complex is efficiently degraded due to photo-Fenton process even at circumneutral pH values due to the high stability of the formed complex. Finally, after LC/FT-ICR MS analysis, 39 photoproducts are detected, of which the 14 most abundant ones are identified. Results indicate that photoproducts formation is pH and iron dependent.

A chemotherapeutic self-sensibilized drug carrier delivering paclitaxel for the enhanced chemotherapy to human breast MDA-MB-231 cells.

To enhance the chemotherapy effect to MDA-MB-231, a glutathione (GSH)-sensitive amphiphilic hyperbranched poly (amide-amine) (mPEG-PLGA-HPAA) was synthesized, and the anti-cancer drug, paclitaxel (PTX) was then encapsulated into the mPEG-PLGA-HPAA micelles. The mPEG-PLGA-HPAA containing a large number of disulfide bonds could degrade and then consume the GSH intracellularly, which was expected to enhances the sensitivity of MDA-MB-231 cells to PTX. It was found that the mPEG-PLGA-HPAA/PTX nanoparticles could respond to the GSH and showed a GSH-controlled PTX release. Simultaneously, the mPEG-PLGA-HPAA/PTX nanoparticles significantly enhanced the efficacy of PTX by inhibiting MDA-MB-231 cells proliferation and inducing cells apoptosis, performing the self-sensitization effect of chemotherapy. Moreover, the drug carrier of mPEG-PLGA-HPAA exhibited excellent biocompatibility in vitro and in vivo. These results indicated that the self-sensitized drug carrier is a promising route to maximize the therapeutic effect and minimize the side effects of chemotherapy drugs used currently in clinical.

Self-Sensitization and Photo-Polymerization of Diacetylene Molecules Self-Assembled on a Hexagonal-Boron Nitride Nanosheet.

Long poly-diacetylene chains are excellent candidates for planar, on-surface synthesized molecular electronic wires. Since hexagonal-Boron Nitride (h-BN) was identified as the best available atomically flat insulator for the deposition of poly-diacetylene precursors, we demonstrate the polymerization patterns and rate on it under UV-light irradiation, with subsequent polymer identification by atomic force microscopy. The results on h-BN indicate self-sensitization which yields blocks comprised of several polymers, unlike on the well-studied graphite/diacetylene system, where the polymers are always isolated. In addition, the photo-polymerization proceeds at least 170 times faster on h-BN, where it also results in longer polymers. Both effects are explained by the h-BN bandgap, which is larger than the diacetylene electronic excitation energy, thus allowing the transfer of excess energy absorbed by polymerized wires to adjacent monomers, triggering their polymerization. This work sets the stage for conductance measurements of single molecular poly-diacetylene wires on h-BN.

Síndrome de Gardner-Diamond.: Presentación de un caso / Gardner-Diamond syndrome:: A case presentation

Se presenta el caso de una mujer de 44 años, blanca, ingresada en el Servicio de Medicina Interna del Hospital Clinicoquirúrgico Docente "Miguel Enríquez" por síndrome febril agudo y hematuria. En el examen físico realizado se notó la salida de lágrimas con sangre muy fluida, por el ángulo externo del ojo izquierdo. La inyección intradérmica en la cara dorsal del muslo derecho de 0,1 mL de sangre autóloga, indujo una reacción equimótica dolorosa en el sitio de la inyección. La inyección de 0,1 mL de solución salina al 0,9 % como control en el muslo contralateral, resultó negativa. Sobre la base del examen clínico y estas pruebas, se concluyó como un Síndrome de Gardner-Diamond. Esta entidad debe ser considerada en el diagnóstico diferencial de un síndrome purpúrico de etiología no bien precisada, fundamentalmente en pacientes con problemas psiquiátricos.

This is the case of a white woman aged 44, admitted in the Internal Medicine Service of "Miguel Enríquez" Clinical Surgical Hospital due to acute febrile syndrome and hematuria. At physical examination performed we noted a very high level of watering with presence of blood by left angle of left eye. The intradermal injection of 0,1 ml of autologous blood in dorsal part of right thigh, induced a painful ecchymotic reaction in injection site. The injection of 0.1 ml of 0,9% saline solution as control in contralateral thigh was negative. On the base of clinical examination and these tests, we conclude that it was a Gardner-Diamond syndrome. This entity must to be considered in differential diagnosis of a purpuric syndrome of a non-well established etiology, mainly in patients presenting with psychiatric disorders.