No abstract

The mechanical properties of cell microenvironments, cells themselves and the linking biomolecular constituents are increasingly recognized as important parameters in understanding and controlling cell behaviour. Specifically, cell adhesionthe first step of interactioncontrols many processes in cell signalling. In this context the viscoelastic characteristics of involved biopolymer systems have to be considered as a key to the understanding of the underlying mechanisms. While elasticity is currently heavily addressed in biophysical and biomaterials science, studies on viscous and dissipative contributions are underrepresented and their impact is frequently neglected. In this review we point out that there is a need to overcome this imbalance and to reveal the impact of dissipative processes in cellmatrix interaction.

We report on temperature-dependent (10 K – 250 K) spectral and dynamical properties of free exciton–polariton and bound exciton emission in copper iodide (CuI) bulk single crystals analyzed by means of time-resolved photoluminescence spectroscopy. The characteristic line shape of the polariton emission at low temperatures is interpreted in terms of the “k-linear term effect” on the degenerate Z1,2 excitons in CuI. For free exciton–polaritons, an increase in the decay time with increasing temperature up to 360 ps at 160 K is observed. For bound exciton emission, decay times between 180 ps and 380 ps are observed at low temperatures, revealing the expected EB3/2 dependence of radiative lifetime on the localization energy. Based on the observed rise times of bound excitons at low temperatures, a defect density of shallow acceptors of 1 × 1017 cm−3 was estimated, in agreement with measured room temperature free hole density.

Self-assembled phospholipid vesicles are functionalized with thrombin-binding aptamers using a thiol-click reaction. The resulting aptasensors signal the binding of the analyte to the vesicle surface by changes of the emission properties of membrane co-embedded reporter dyes.