Oxygen mapping of melanoma spheroids using small molecule platinum probe and phosphorescence lifetime imaging microscopy

Solid tumours display varied oxygen levels and this characteristic can be exploited to develop new diagnostic tools to determine and exploit these variations. Oxygen is an efficient quencher of emission of many phosphorescent compounds, thus oxygen concentration could in many cases be derived directly from relative emission intensity and lifetime. In this study, we extend our previous work on phosphorescent, low molecular weight platinum(II) complex as an oxygen sensing probe to study the variation in oxygen concentration in a viable multicellular 3D human tumour model. The data shows one of the first examples of non-invasive, real-time oxygen mapping across a melanoma tumour spheroid using one-photon phosphorescence lifetime imaging microscopy (PLIM) and a small molecule oxygen sensitive probe. These measurements were quantitative and enabled real time oxygen mapping with high spatial resolution. This combination presents as a valuable tool for optical detection of both physiological and pathological oxygen levels in a live tissue mass and we suggest has the potential for broader clinical application

Factors Associated with Step Numbers in Acutely Hospitalized Older Adults: The Hospital-Activities of Daily Living Study

ObjectivesTo determine the number of steps taken by older patients in hospital and 1 week after discharge; to identify factors associated with step numbers after discharge; and to examine the association between functional decline and step numbers after discharge.DesignProspective observational cohort study conducted in 2015–2017.Setting and ParticipantsOlder adults (≥70 years of age) acutely hospitalized for at least 48 hours at internal, cardiology, or geriatric wards in 6 Dutch hospitals.MethodsSteps were counted using the Fitbit Flex accelerometer during hospitalization and 1 week after discharge. Demographic, somatic, physical, and psychosocial factors were assessed during hospitalization. Functional decline was determined 1 month after discharge using the Katz activities of daily living index.ResultsThe analytic sample included 188 participants [mean age (standard deviation) 79.1 (6.7)]. One month postdischarge, 33 out of 174 participants (19%) experienced functional decline. The median number of steps was 656 [interquartile range (IQR), 250–1146] at the last day of hospitalization. This increased to 1750 (IQR 675–4114) steps 1 day postdischarge, and to 1997 (IQR 938–4098) steps 7 days postdischarge. Age [β = −57.93; 95% confidence interval (CI) −111.15 to −4.71], physical performance (β = 224.95; 95% CI 117.79–332.11), and steps in hospital (β = 0.76; 95% CI 0.46–1.06) were associated with steps postdischarge. There was a significant association between step numbers after discharge and functional decline 1 month after discharge (β = −1400; 95% CI –2380 to −420; P = .005).Conclusions and ImplicationsAmong acutely hospitalized older adults, step numbers double 1 day postdischarge, indicating that their capacity is underutilized during hospitalization. Physical performance and physical activity during hospitalization are key to increasing the number of steps postdischarge. The number of steps 1 week after discharge is a promising indicator of functional decline 1 month after discharge

A dinuclear ruthenium(II) complex excited by near-infrared light through two-photon absorption induces phototoxicity deep within hypoxic regions of melanoma cancer spheroids

The dinuclear photo-oxidizing RuII complex [{Ru(TAP2)}2(tpphz)]4+ (TAP = 1,4,5,8- tetraazaphenanthrene, tpphz = tetrapyrido[3,2-a:2',3'-c:3'',2''- h:2''',3'''-j]phenazine), 14+ is readily taken up by live cells localizing in mitochondria and nuclei. In this study, the two-photon absorption cross-section of 14+ is quantified and its use as a two-photon absorbing phototherapeutic is reported. It was con-firmed that the complex is readily photo-excited using near infrared, NIR, light through two-photon absorption, TPA. In 2-D cell cul-tures, irradiation with NIR light at low power results in precisely focused photo-toxicity effects in which human melanoma cells were killed after 5 minutes of light exposure. Similar experiments were then carried out in human cancer spheroidsthat provide a realistic tumor model for the development of therapeutics and phototherapeutics. Using the characteristic emission of the complex as a probe, its up-take into 280 µm spheroids was investigated and confirmed that the spheroid takes up the complex. Notably TPA excitation results in more intense luminescence being observed throughout the depth of the spheroids, although emission intensity still drops off toward the necrotic core. As 14+ can directly photo-oxidize DNA without the mediation of singlet oxygen or other reactive oxygen species, photo-toxicity within the deeper, hypoxic layers of the spheroids was also investigated. To quantify the penetration of these phototoxic effects, 14+ was photo-excited through TPA at a power of 60 mW, which was progressively focused in 10 µm steps throughout the entire z-axis of individual spheroids. These experiments revealed that, in irradiated spheroids treated with 14+, acute and rapid photo-induced cell death was observed throughout their depth, including the hypoxic region

A dinuclear ruthenium(II) phototherapeutic that targets duplex and quadruplex DNA

With the aim of developing a sensitizer for photodynamic therapy, a previously reported luminescent dinuclear complex that functions as a DNA probe in live cells was modified to produce a new iso-structural derivative containing RuII(TAP)2 fragments (TAP = 1,4,5,8-tetraazaphenanthrene). The structure of the new complex has been confirmed by a variety of techniques including single crystal X-ray analysis. Unlike its parent, the new complex displays Ru → L-based 3MLCT emission in both MeCN and water. Results from electrochemical studies and emission quenching experiments involving guanosine monophosphate are consistent with an excited state located on a TAP moiety. This hypothesis is further supported by detailed DFT calculations, which take into account solvent effects on excited state dynamics. Cell-free steady-state and time-resolved optical studies on the interaction of the new complex with duplex and quadruplex DNA show that the complex binds with high affinity to both structures and indicate that its photoexcited state is also quenched by DNA, a process that is accompanied by the generation of the guanine radical cation sites as photo-oxidization products. Like the parent complex, this new compound is taken up by live cells where it primarily localizes within the nucleus and displays low cytotoxicity in the absence of light. However, in complete contrast to [{RuII(phen)2}2(tpphz)]4+, the new complex is therapeutically activated by light to become highly phototoxic toward malignant human melanoma cell lines showing that it is a promising lead for the treatment of this recalcitrant cancer