Oxygen Assessment in Tumors In Vivo Using Phosphorescence Lifetime Imaging Microscopy.

The oxygen level in a tumor is a crucial factor for its development and response to therapies. Phosphorescence lifetime imaging (PLIM) with the use of phosphorescent oxygen probes is a highly sensitive, noninvasive optical technique for the assessment of molecular oxygen in living cells and tissues. Here, we present a protocol for microscopic mapping of oxygen distribution in a mouse tumor model in vivo. We demonstrate that PLIM microscopy, in combination with an Ir(III)-based probe, enables visualization of cellular-level heterogeneity of tumor oxygenation.

Dosis de radiación por radiografías y factores asociados en neonatos de la Unidad de Recién Nacidos del Hospital Universitario San Ignacio, Bogotá, Colombia / X-ray radiation dose and associated factors in neonates from the newborn unit of Hospital Universitario San Ignacio, Bogotá, Colombia

Introducción. Las radiografías continúan usándose ampliamente, subestimando los riesgos. Esto sucede, especialmente, en las unidades de cuidado neonatal, lo que implica que los neonatos reciben una dosis de radiación ionizante mayor que los adultos. Objetivo. Cuantificar las dosis de radiación recibidas al tomar radiografías y evaluar los posibles factores asociados con el aumento de la dosis. Materiales y métodos. Se llevó a cabo un estudio observacional de 160 neonatos de la Unidad de Recién Nacidos del Hospital Universitario San Ignacio, Bogotá, Colombia. Se consideró como variable dependiente la dosis de entrada en piel por cada radiografía. Se hizo la caracterización de los pacientes, seguida de un análisis multivariado con regresión lineal múltiple para identificar factores asociados. Resultados. Se analizaron 160 pacientes y 492 radiografías en total. Entre los hallazgos más frecuentes, se encuentran: pacientes de sexo masculino (n=87; 54,4 %), nacimiento por cesárea (n=122; 76,3 %) e indicación de toma de radiografías por dificultad respiratoria (n=123; 24,9 %). El 1,8 % (n=9) de los pacientes no tenían una indicación para la toma de la radiografía. La radiografía más frecuente fue la de tórax (n=322; 65,4 %). La mayoría de las radiografías se tomaron con el equipo computarizado (n=352; 71,5 %) y no con el digital (n=140, 28,4 %). La mediana de la dosis de entrada en piel con el equipo computarizado fue de 0,112 mGy (0,022; 0,134 mGy) y, con el equipo digital, de 0,020 mGy (0,019, 0,022 mGy). Conclusiones. Se cuantificaron las dosis de radiación absorbida en neonatos, general y específica, con el equipo computarizado y el digital. Se identificaron mayores dosis con el equipo computarizado. Se reconoció la interacción entre el equipo computarizado con menores edades gestacionales corregidas como principal factor para el aumento de la dosis. Además, se reconoció la relación entre el equipo computarizado y una menor edad gestacional corregida, como principal factor para una mayor dosis.

Introduction. Radiographs are still widely used, underestimating the risks. This situation is frequent in neonatal care units, generating radiation doses than in adults. Objective. To quantify the received radiation doses when performing radiographs on neonates and the possible factors associated with higher doses. Materials and methods. We performed an observational study of 160 neonates from the newborn unit of the Hospital Universitario San Ignacio, Bogotá, Colombia. We considered the input dose of each radiograph as the dependent variable. Patients were characterized and a multivariate analysis with multiple linear regression was performed to identify associated factors. Results. We analyzed 160 newborns and 492 radiographs. The most frequent findings were male patients (n=87, 54.4%), cesarean delivery (n=122, 76.3%), and radiograph indication for respiratory distress (n=123, 24.9%). One-point eight percent of the patients (n=9) did not have radiograph indication. The most frequently taken radiograph was chest (322, 65.4%). Most radiographs were taken with a computerized equipment (n=352, 71.5%), compared to a digital one (n=140, 28.4%). The median input dose with computerized equipment was 0.112 mGy (0.022, 0.134 mGy), and with the digital equipment was 0.020 mGy (0.019, 0.022 mGy). Conclusions. The general and specific absorbed radiation doses were measured in neonates with a computerized and a digital equipment. We identified higher doses with the computerized equipment. In addition, it was recognized the correlation between computerized radiography equipment with lower corrected gestational ages as the main factor for dose increase.

Construction of room temperature phosphorescent materials with ultralong lifetime by in-situ derivation strategy.

Although room temperature phosphorescence (RTP) materials have been widely investigated, it is still a great challenge to improve the performance of RTP materials by promoting triplet exciton generation and stabilization. In this study, an in-situ derivation strategy was proposed to construct efficient RTP materials by in-situ deriving guest molecules and forming a rigid matrix during co-pyrolysis of guest molecules and urea. Characterizations and theoretical calculations revealed that the generated derivatives were beneficial for promoting intersystem crossing (ISC) to produce more triplet excitons, while rigid matrix could effectively suppress the non-radiative transition of triplet excitons. Thus, the in-situ derivation strategy was concluded to simultaneously promote the generation and stabilization of triplet excitons. With this method, the ultralong lifetime of RTP materials could reach up to 5.33 s and polychromatic RTP materials were easily achieved. Moreover, the potential applications of the RTP materials in reprocessing or editable anti-counterfeiting were successfully demonstrated.

Multi-Resonant Indolo[3,2,1-jk]carbazole-Based Host for Blue Phosphorescent Organic Light-Emitting Diodes.

In organic light-emitting diodes, positive and negative charge carriers mostly migrate at different rates. This could result in excitons formed in the EML often migrating to the vicinity of the hole transport layer and the electron transport layer. To address this, it is important to design high-quality multi-resonance hosts that can balance the migration rate of carriers. Here, we report two newly developed multi-resonance hosts, m-ICzPBI and o-ICzPBI. The hosts contain an indolo[3,2,1-jk]carbazole (ICz) motif, which functionalized as either a donor or an acceptor unit. The hosts exhibit extremely high molecular rigidity and thermal stability. Devices A and B were constructed using FIrpic as a phosphorescent emitter with m-ICzPBI or o-ICzPBI as a host. Device A achieved high maximum values of EQE, PE and CE of 13.4%, 24.8 lm W-1 and 31.6 cd A-1, respectively, and low efficiency roll-off at 5000 cd m-2 of 8.6%, 10.6 lm W-1 and 20.3 cd A-1, respectively.

A Comparison between Triphenylmethyl and Triphenylsilyl Spirobifluorenyl Hosts: Synthesis, Photophysics and Performance in Phosphorescent Organic Light-Emitting Diodes.

This study presents the synthesis and characterization of two spirobifluorenyl derivatives substituted with either triphenylmethyl (SB-C) or triphenylsilyl (SB-Si) moieties for use as host materials in phosphorescent organic light-emitting diodes (PHOLED). Both molecules have similar high triplet energies and large energy gaps. Blue Ir(tpz)3 and green Ir(ppy)3 phosphorescent devices were fabricated using these materials as hosts. Surprisingly, SB-Si demonstrated superior charge-transporting ability compared to SB-C, despite having similar energies for their valence orbitals. In particular, SB-Si proved to be a highly effective host for both blue and green devices, resulting in maximum efficiencies of 12.6% for the Ir(tpz)3 device and 9.6% for the Ir(ppy)3 device. These results highlight the benefits of appending the triphenylsilyl moiety onto host materials and underscore the importance of considering the morphology of hosts in the design of efficient PHOLEDs.

Intervenções psicológicas necessárias: a prática como residente no serviço de medicina fetal / Necessary psychological interventions: the practice as a resident in the fetal medicine service / Intervenciones psicológicas necesarias: la práctica como residente en el servicio de medicina fetal

Com os avanços tecnológicos e o aprimoramento da prática médica via ultrassonografia, já é possível detectar possíveis problemas no feto desde a gestação. O objetivo deste estudo foi analisar a prática do psicólogo no contexto de gestações que envolvem riscos fetais. Trata-se de um estudo qualitativo sob formato de relato de experiência como psicólogo residente no Serviço de Medicina Fetal da Maternidade Escola da Universidade Federal do Rio de Janeiro (UFRJ). Os registros, feitos por observação participante e diário de campo, foram analisados em dois eixos temáticos: 1) intervenções psicológicas no trabalho em equipe em consulta de pré-natal, exame de ultrassonografia e procedimento de amniocentese; e 2) intervenções psicológicas em casos de bebês incompatíveis com a vida. Os resultados indicaram que o psicólogo nesse serviço é essencial para atuar de forma multiprofissional na assistência pré-natal para gravidezes de alto risco fetal. Ademais, a preceptoria do residente é relevante para sua formação e treinamento para atuação profissional no campo da psicologia perinatal.(AU)

Face to the technological advances and the improvement of medical practice via ultrasound, it is already possible to detect possible problems in the fetus since pregnancy. The objective of this study was to analyze the psychologist's practice in the context of pregnancies which involve fetal risks. It is a qualitative study based on an experience report as a psychologist trainee at the Fetal Medicine Service of the Maternity School of UFRJ. The records, based on the participant observation and field diary, were analyzed in two thematic axes: 1) psychological interventions in the teamwork in the prenatal attendance, ultrasound examination and amniocentesis procedure; and 2) psychological interventions in cases of babies incompatible to the life. The results indicated that the psychologist in this service is essential to work in a multidisciplinary way at the prenatal care for high fetal risk pregnancies. Furthermore, the resident's preceptorship is relevant to their education and training for professional performance in the field of Perinatal Psychology.(AU)

Con los avances tecnológicos y la mejora de la práctica médica a través de la ecografía, ya se puede detectar posibles problemas en el feto desde el embarazo. El objetivo de este estudio fue analizar la práctica del psicólogo en el contexto de embarazos de riesgos fetal. Es un estudio cualitativo basado en un relato de experiencia como residente de psicología en el Servicio de Medicina Fetal de la Escuela de Maternidad de la Universidade Federal do Rio de Janeiro (UFRJ). Los registros, realizados en la observación participante y el diario de campo, se analizaron en dos ejes temáticos: 1) intervenciones psicológicas en el trabajo en equipo, en la consulta prenatal, ecografía y los procedimientos de amniocentesis; y 2) intervenciones psicológicas en casos de bebés incompatibles con la vida. Los resultados señalaron como fundamental la presencia del psicólogo en este servicio trabajando de forma multidisciplinar en la atención prenatal en el contexto de embarazos de alto riesgo fetal. Además, la tutela del residente es relevante para su educación y formación para el desempeño profesional en el campo de la Psicología Perinatal.(AU)

Reducing the risks of nuclear war - the role of health professionals

@#In January, 2023, the Science and Security Board of the Bulletin of the Atomic Scientists moved the hands of the Doomsday Clock forward to 90’s before midnight, reflecting the growing risk of nuclear war.1 In August, 2022, the UN Secretary-General António Guterres warned that the world is now in “a time of nuclear danger not seen since the height of the Cold War.2 The danger has been underlined by growing tensions between many nuclear armed states.1,3 As editors of health and medical journals worldwide, we call on health professionals to alert the public and our leaders to this major danger to public health and the essential life support systems of the planet—and urge action to prevent it.

Time to treat the climate and nature crisis as one indivisible Global Health Emergency

@#Over 200 health journals call on the United Nations, political leaders, and health professionals to recognise that climate change and biodiversity loss are one indivisible crisis and must be tackled together to preserve health and avoid catastrophe. This overall environmental crisis is now so severe as to be a global health emergency.

On the brink: The climate and nature crisis and risks of nuclear war

@#The Russian military invasion of Ukraine on February 24, 2022, and Hamas’ terror attack on Israel on October 7, 2023, signaled the beginning of two of the most recent wars to make international headlines. To date, over 110 armed conflicts are taking place: over 45 in the Middle East and North Africa (Cyprus, Egypt, Iraq, Israel, Libya, Morocco, Palestine, Syria, Turkey, Yemen, Western Sahara); over 35 in Africa (Burkina Faso, Cameroon, the Central African Republic, the Democratic Republic of the Congo, Ethiopia, Mali, Mozambique, Nigeria, Senegal, Somalia, South Sudan, Sudan); 21 in Asia (Afghanistan, India, Myanmar, Pakistan, the Philippines); seven in Europe (Russia, Ukraine, Moldova, Georgia, Armenia, Azerbaijan); and six in Latin America (three each in Mexico and Colombia); with two more international armed conflicts (between India and Pakistan, and between India and China) in Asia.1 This list does not even include such problematic situations as those involving China and the South East Asia region. As though these situations of armed violence were not enough, mankind has already passed or is on the verge of passing several climate tipping points – a recent review lists nine Global core tipping elements (and their tipping points) - the Greenland Ice Sheet (collapse); West Antarctic Ice Sheet (collapse); Labrador-Irminger Seas / SPG Convection (collapse); East Antarctic Subglacial Basins (collapse); Amazon Rainforest (dieback); Boreal Permafrost (collapse); Atlantic M.O. Circulation (collapse); Arctic Winter Sea Ice (collapse); and East Antarctic Ice Sheet (collapse); and seven Regional impact tipping elements (and their tipping points) – Low-latitude Coral Reefs (die-off); Boreal Permafrost (abrupt thaw); Barents Sea Ice (abrupt loss); Mountain Glaciers (loss); Sahel and W. African Monsoon (greening); Boreal Forest (southern dieback); and Boreal Forest (northern expansion).2 Closer to home, how can we forget the disaster and devastation wrought by Super Typhoon Haiyan (Yolanda) 10 years ago to date? Whether international or non-international, armed conflicts raise the risk of nuclear war. Russia has already “rehearsed its ability to deliver a ‘massive’ nuclear strike,” conducting “practical launches of ballistic and cruise missiles,” and stationed a first batch of tactical nuclear weapons in Belarus,3 and the possibility of nuclear escalation in Ukraine cannot be overestimated.4 Meanwhile, in a rare public announcement, the U.S. Central Command revealed that an Ohio- class submarine (560 feet long, 18,750 tons submerged and carrying as many as 154 Tomahawk cruise missiles) had arrived in the Middle East on November 5, 2023.5 Indeed, “the danger is great and growing,” as “any use of nuclear weapons would be catastrophic for humanity.”

Impact of photoinitiator quality on chemical-mechanical properties of dental adhesives under different light intensities / Impacto da qualidade de fotoiniciadores nas propriedades químico mecânicas de adesivos dentais sob diferentes intensidades de luz

Objective: Evaluate the mechanical properties of experimental adhesive models with different photoinitiators (PI) polymerized by LED units of different power densities. Material and Methods: Three groups of adhesive models based on HEMA/BisGMA (45/55) were prepared in association with different PI combinations: G2 (control) ­ 2 PI: 0.5% CQ, 0.5% EDMAB; G3 - 3 PI: 0.5% CQ; 0.5% DMAEMA, 0.5% DPIHP; G4 - 4 PI: 0.5% CQ; 0.5% EDMAB; 0.5% DMAEMA; 0.5% DPIHP. The three formulations were polymerized at two different LED power densities: 550 mW/cm2 and 1200 mW/cm2. The degree of conversion (DC) of adhesive monomers was monitored in situ through the FTIR for 600 s. Specimens were prepared for each formulation for analysis mong adhesive systems (G2

Objetivo: Avaliar as propriedades mecânicas de modelos adesivos experimentais com diferentes fotoiniciadores (PI) polimerizados por unidades de LED de diferentes densidades de energia. Material e Métodos: Três grupos de modelos adesivos baseados em HEMA/BisGMA (45/55) foram preparados em associação com diferentes combinações de PI: G2 (controle) ­ 2 PI: 0,5% CQ, 0,5% EDMAB; G3 - 3PI: 0,5% CQ; 0,5% DMAEMA, 0,5% DPIHP; G4 - 4 PI: 0,5% CQ; 0,5% EDMAB; 0,5% DMAEMA; 0,5% DPIHP. As três formulações foram polimerizadas em duas densidades de potência de LED: 550 mW/cm2 e 1200 mW/cm2. O grau de conversão (DC) dos monômeros adesivos foi monitorado in situ através do FTIR durante 600 s. Amostras foram preparadas para cada formulação para análise de resistência à flexão (FS), módulo de elasticidade (ME), sorção (SOR) e solubilidade (SOL). Os dados foram submetidos aos testes ANOVA 2-fatores e Tukey (5%). Resultados: DC: houve diferença significativa entre os sistemas adesivos (G2

Slow dynamics measured by phosphorescence lifetime reveals global conformational changes in human adult hemoglobin induced by allosteric effectors.

The mechanism underlying allostery in hemoglobin (Hb) is still not completely understood. Various models describing the action of allosteric effectors on Hb function have been published in the literature. It has also been reported that some allosteric effectors-such as chloride ions, inositol hexaphosphate, 2,3-diphospho-glycerate and bezafibrate-considerably lower the oxygen affinity of Hb. In this context, an important question is the extent to which these changes influence the conformational dynamics of the protein. Earlier, we elaborated a challenging method based on phosphorescence quenching, which makes characterizing protein-internal dynamics possible in the ms time range. The experimental technique involves phosphorescence lifetime measurements in thermal equilibrium at varied temperatures from 10 K up to 273 K, based on the signal of Zn-protoporphyrin substituted for the heme in the ß-subunits of Hb. The thermal activation of protein dynamics was observed by the enhancement of phosphorescence quenching attributed to O2 diffusion. It was shown that the thermal activation of protein matrix dynamics was clearly distinguishable from the dynamic activation of the aqueous solvent, and was therefore highly specific for the protein. In the present work, the same method was used to study the changes in the parameters of the dynamic activation of human HbA induced by binding allosteric effectors. We interpreted the phenomenon as phase transition between two states. The fitting of this model to lifetime data yielded the change of energy and entropy in the activation process and the quenching rate in the dynamically activated state. The fitted parameters were particularly sensitive to the presence of allosteric effectors and could be interpreted in line with results from earlier experimental studies. The results suggest that allosteric effectors are tightly coupled to the dynamics of the whole protein, and thus underline the importance of global dynamics in the regulation of Hb function.

Radiación y medios de contraste en embarazo y lactancia: lo que el clínico necesita saber / Radiation and contrast media in pregnancy and lactation: what the clinician needs to know

Introducción: el uso de técnicas de imagenología es habitual e incluso indispensable en algunos procesos diagnósticos. Sin embargo, su indicación en mujeres embarazadas y en período de lactancia es controvertida. Objetivo: presentar una revisión narrativa sobre los riesgos asociados al uso de imágenes con radiación y medio de contraste en embarazo y periodo de lactancia, con énfasis en las recomendaciones y aplicaciones clínicas que el médico tratante debe tener presente al momento de su indicación. Métodos: se realizó una revisión bibliográfica de la literatura relevante sobre los riesgos y consideraciones especiales del uso de medios de contraste en el embarazo y lactancia. Resultados: los riesgos de la radiación ionizante sobre el feto varían de acuerdo al estadio del embarazo, por lo que la indicación del estudio debe ponderar los riesgos y beneficios. En las dosis clínicas en embarazo y lactancia, el uso de contraste yodado como basados en gadolinio no tienen efectos deletéreos en la salud de la madre ni la del feto. Sin embargo, las sociedades internacionales recomiendan limitar su uso. Conclusión: si bien la indicación de estudios de imagen que utilizan radiación ionizante en el embarazo y lactancia es seguro, el médico clínico debe conocer los posibles riesgos de la radiación ionizante en este grupo de pacientes. Respecto a los medios de contraste, el único efecto adverso reportado es la disfunción tiroidea transitoria en hijos de madres que recibieron medios de contraste yodado.

Introduction: the use of imaging techniques is essential in some diagnostic processes. However, its indication in pregnant and lac-tating women is controversial. Objective: To present a narrative review of the risks associated with using images with radiation and contrast media in pregnancy and lactation. Emphasis will be put on the recommendations and clinical applications that the physician must consider before its indication. Methods: a bibliographic review of the relevant literature on the risks and special considerations of contrast media in pregnancy and lactation was performed. Results: the risks of ionising radiation on the fetus vary according to the stage of pregnancy, so the indication of the study must balance the risks and benefits. The use of iodinated and gadolinium-based con-trast agents in clinical doses in pregnancy and lactation has no effects on the health of the mother or the fetus. However, international societies recommend limiting its use. Conclusion: Although the indication for imaging studies using ionising radiation in pregnancy and lactation is safe, the clinician must be aware of the possible risks of ionising radiation in this group of patients. The only adverse effect reported is transient thyroid dysfunction in children of mothers who received iodinated contrast media.

Structural materials with afterglow room temperature phosphorescence activated by lignin oxidation.

Sustainable afterglow room temperature phosphorescence (RTP) materials, especially afterglow RTP structural materials, are crucial but remain difficult to achieve. Here, an oxidation strategy is developed to convert lignin to afterglow materials with a lifetime of ~ 408 ms. Specifically, lignin is oxidized to give aromatic chromophores and fatty acids using H2O2. The aromatic chromophores are locked by a fatty acid-based matrix by hydrogen bonds, triggering enhanced spin orbit coupling and long afterglow emission. More interestingly, motivated by this discovery, an auto fabrication line is built to convert wood (natural structural materials) to wood with afterglow RTP emission (RTP wood) via in situ oxidation of naturally-occurring lignin located in the wood cell walls to oxidized lignin (OL). The as-prepared RTP wood exhibits great potential for the construction of sustainable afterglow furniture. With this research we provide a new strategy to promote the sustainability of afterglow RTP materials and structural materials.

Ultralarge Stokes Shift Phosphorescence Artificial Harvesting Supramolecular System with Near-Infrared Emission.

A two-step sequential phosphorescence harvesting system with ultralarge Stokes shift and near-infrared (NIR) emission at 825 nm is successfully constructed by racemic 1,2-diaminocyclohexan-derived 6-bromoisoquinoline (BQ), cucurbit[8]uril (CB[8]), and amphipathic sulfonatocalix[4]arene (SC4AD) via cascaded assembly strategy in aqueous solution. In virtue of the confinement effect of CB[8] with rigid cavity, BQ can generate an emerging phosphorescent emission at 555 nm. Subsequently, the binary BQ⊂CB[8] further assemblies with SC4AD to form close-packed spherical aggregate, which contributes to the dramatic enhancement of phosphorescence emission intensity ≈30 times with prolonged lifetime from 21.3 µs to 0.364 ms. Notably, the BQ⊂CB[8]@SC4AD assembly can serve as an energy donor to conduct stepwise phosphorescence harvesting process through successive introduction of primary acceptors, cyanine 5 (Cy5) or nile blue (NiB), and secondary acceptor, heptamethine cyanine (IR780). The final aggregate with remarkable ultralarge Stokes shift (≈525 nm) and long-lived NIR photoluminescence (PL) emission at 825 nm is further employed as imaging agent for NIR cell labeling.

Clustering and halogen effects enabled red/near-infrared room temperature phosphorescence from aliphatic cyclic imides.

Pure organic room temperature phosphorescence (RTP) materials become increasingly important in advanced optoelectronic and bioelectronic applications. Current phosphors based on small aromatic molecules show emission characteristics generally limited to short wavelengths. It remains an enormous challenge to achieve red and near-infrared (NIR) RTP, particularly for those from nonaromatics. Here we demonstrate that succinimide derived cyclic imides can emit RTP in the red (665, 690 nm) and NIR (745 nm) spectral range with high efficiencies of up to 9.2%. Despite their rather limited molecular conjugations, their unique emission stems from the presence of the imide unit and heavy atoms, effective molecular clustering, and the electron delocalization of halogens. We further demonstrate that the presence of heavy atoms like halogen or chalcogen atoms in these systems is important to facilitate intersystem crossing as well as to extend through-space conjugation and to enable rigidified conformations. This universal strategy paves the way to the design of nonconventional luminophores with long wavelength emission and for emerging applications.

The Global Experiment: How the International Atomic Energy Agency Proved Dosimetry to Be a Techno-Diplomatic Issue.

This paper draws attention to the role of the IAEA in shaping radiation dosimetry practices, instrumentation, and standards in the late 1950s and 1960s. It traces the beginnings of the IAEA's radiation dose intercomparison program which targeted all member states and involved the WHO so as to standardize dosimetry on a global level. To standardize dosimetric measurement methods, techniques, and instruments, however, one had to devise a method of comparing absorbed dose measurements in one laboratory with those performed in others with a high degree of accuracy. In 1964 the IAEA thus started to build up what I call the "global experiment," an intercomparison of radiation doses with participating laboratories from many of its member states. To carry out the process of worldwide standardization in radiation dosimetry, I argue, an organization with the diplomatic power and global reach of the IAEA was absolutely necessary. Thus, "global experiment" indicates a novel understanding of the experimental process. What counts as an experiment became governed by a process that was designed and strictly regulated by an international organization; it took place simultaneously in several laboratories across the globe, while experimental data became centrally owned and alienated from those that produced it.

Novel NIR-Phosphorescent Ir(III) Complexes: Synthesis, Characterization and Their Exploration as Lifetime-Based O2 Sensors in Living Cells.

A series of [Ir(N^C)2(N^N)]+ NIR-emitting orthometalated complexes (1-7) has been prepared and structurally characterized using elemental analysis, mass-spectrometry, and NMR spectroscopy. The complexes display intense phosphorescence with vibrationally structured emission bands exhibiting the maxima in the range 713-722 nm. The DFT and TD DFT calculations showed that the photophysical characteristics of these complexes are largely determined by the properties of the metalating N^C ligands, with their major contribution into formation of the lowest S1 and T1 excited states responsible for low energy absorption and emission, respectively. Emission lifetimes of 1-7 in degassed methanol solution vary from 1.76 to 5.39 µs and show strong quenching with molecular oxygen to provide an order of magnitude lifetime reduction in aerated solution. The photophysics of two complexes (1 and 7) were studied in model physiological media containing fetal bovine serum (FBS) and Dulbecco's Modified Eagle Medium (DMEM) to give linear Stern-Volmer calibrations with substantially lower oxygen-quenching constants compared to those obtained in methanol solution. These observations were interpreted in terms of the sensors' interaction with albumin, which is an abundant component of FBS and cell media. The studied complexes displayed acceptable cytotoxicity and preferential localization, either in mitochondria (1) or in lysosomes (7) of the CHO-K1 cell line. The results of the phosphorescence lifetime imaging (PLIM) experiments demonstrated considerable variations of the sensors' lifetimes under normoxia and hypoxia conditions and indicated their applicability for semi-quantitative measurements of oxygen concentration in living cells. The complexes' emission in the NIR domain and the excitation spectrum, extending down to ca. 600 nm, also showed that they are promising for use in in vivo studies.

Ultrawide-range radiation detection based on dynamic identification and analysis of the response of a monolithic active pixel sensor.

In this paper, we present an ultrawide-range radiation detection method based on dynamic recognition and analysis of the response signal of a monolithic active pixel sensor (MAPS). Our analysis of the MAPS response mechanism determined that adaptive adjustment of the sensor's integral time is key to quantification of ionizing radiation in an ultrawide range. We also determined that different data processing methods are required for accurate quantification of high and low radiation dose rates. The results of experiments conducted after calibration demonstrate that our technique is capable of radiation detection across five orders of magnitude (ranging from milligrays per hour to hundreds of grays per hour), with errors of less than 5%. Chip-based nuclear radiation detection can be realized using our technique, enabling MAPS to be used as a supplement to traditional detectors in characterization of unknown and complex radiation environments.