BODIPY‐based donor‐acceptor dyads are widely used as sensors and probes in life science. Thus, their biophysical properties are well established in solution, while their photophysical properties in cellulo, i. e., in the environment, in which the dyes are designed to function, are generally understood less. To address this issue, we present a sub‐ns time‐resolved transient absorption study of the excited‐state dynamics of a BODIPY‐perylene dyad designed as a twisted intramolecular charge transfer (TICT) probe of the local viscosity in live cells.

Changes in the urban landscape resulting from rapid urbanisation and climate change have the potential to increase land surface temperature (LST) and the incidence of the urban heat island (UHI). An increase in urban heat directly affects urban livelihoods and systems. This study investigated the spatiotemporal variation of the UHI in the Kurunegala urban area (KUA) of North-Western Province, Sri Lanka. The KUA is one of the most intensively developing economic and administrative capitals in Sri Lanka with an urban system that is facing climate vulnerabilities and challenges of extreme heat conditions. We examined the UHI formation for the period 1996–2019 and its impact on the urban-systems by exploring nature-based solutions (NBS). This study used annual median temperatures based on Landsat data from 1996 to 2019 using the Google Earth Engine (GEE). Various geospatial approaches, including spectral index-based land use/cover mapping (1996, 2009 and 2019), urban-rural gradient zones, UHI profile, statistics and grid-based analysis, were used to analyse the data. The results revealed that the mean LST increased by 5.5 °C between 1996 and 2019 mainly associated with the expansion pattern of impervious surfaces. The mean LST had a positive correlation with impervious surfaces and a negative correlation with the green spaces in all the three time-points. Impacts due to climate change, including positive temperature and negative rainfall anomalies, contributed to the increase in LST. The study recommends interactively applying NBS to addressing the UHI impacts with effective mitigation and adaptation measures for urban sustainability.

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Triplet-triplet annihilation up-conversion (TTAUC) is an emerging technology in photonics with significant potential to impact a variety of fields (e.g. solar cells, bioimaging, drug delivery) due to its ability to convert long-wavelength photons to higher photon energies even at low excitation power densities. However, for many practical applications of TTAUC, the transfer of the upconversion system, consisting of a molecular sensitizer and a molecular annihilator, from solution, in which efficient TTAUC systems have been reported, to solid matrices is required. This is a challenge because diffusion facilitates the close contact between molecular components required for TTET and TTA. To this end, various approaches to fully integrate sensitizer and annihilator into polymers or combining a macromolecular annihilator with monomeric sensitizers have been established. This contribution studies the effect of integrating Ru(dqp)2-inspired molecular sensitizers into the side chains of a PMMA polymer, whichas macromolecular photosensitizeris co-dissolved with 9,10-diphenylanthracene as annihilator. We study the effect of confining the sensitizers into a comparably small volume on the TTAUC process and compare the results to an upconversion system using various concentrations of monomeric annihilator. We show that our approach of using a macromolecular photosensitizer allows for upconversion at extremely low excitation power densities. Furthermore, the onset of the strong annihilation regime, i.e. the regime in which the intensity of the upconverted light scales linearly with the increase of the excitation power, is significantly reduced using the polymeric sensitizer; however, the upconversion intensity sits below the monomeric counterparts.

Cancer epithelia show elevation in levels of sulfated proteoglycans including dermatan sulfates (DS). The effect of increased DS on cancer cell behavior is still unclear. We hypothesized that decreased expression of the enzyme Iduronate-2-sulfatase (IDS) can lead to increased DS levels, which would enhance the invasion of cancer cells. Breast cancer sections shows depleted IDS levels in tumor epithelia, when compared with adjacent untransformed breast tissues. IDS signals showed a progressive decrease in the non-transformed HMLE, transformed but non-invasive MCF-7 and transformed and invasive MDA-MB-231 cells, respectively, when cultured on Type 1 collagen scaffolds. DS levels measured by ELISA increased in an inverse-association with IDS levels. Knockdown of IDS in MCF-7 epithelia also increased the levels of DS. MCF-7 cells with depleted IDS expression, when imaged using two photon-excited fluorescence and second harmonic generation microscopy, exhibited a mesenchymal morphology with multiple cytoplasmic projections compared with epithelioid control cells, interacted with their surrounding matrix, and showed increased invasion through Type 1 collagen matrices. Both these traits were phenocopied when control MCF-7 cells were cultivated on Type 1 collagen gels polymerized in the presence of DS. In monolayer cultures, DS had no effect on MCF-7 migration. In the context of our demonstration that DS enhances the elastic modulus of Type 1 collagen gels, we propose that a decrease of IDS expression leads to accumulation within cancer epithelia of DS: the latter remodels the collagen around cancer cells leading to changes in cell shape and invasiveness through fibrillar matrix milieu.

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Recently, porous photocatalytically active block copolymer membranes were introduced, based on heterogenized molecular catalysts. Here, we report the integration of the photosensitizer, i. e., the light absorbing unit in an intermolecular photocatalytic system into block copolymer membranes in a covalent manner. We study the resulting structure and evaluate the orientational mobility of the photosensitizer as integral part of the photocatalytic system in such membranes. To this end we utilize transient absorption anisotropy, highlighting the temporal reorienta-tion of the transition dipole moment probed in a femtosecond pump-probe experiment. Our findings indicate that the photosensitizer is rigidly bound to the polymer membrane and shows a large heterogeneity of absolute anisotropy values as a function of location probed within the matrix. This reflects the sample inhomogeneity arising from different protonation states of the photosensitizer and different intermolecular interactions of the photosensitizers within the block copolymer membrane scaffold.

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