Reversible growth arrest of 3D tumor spheroids stored in oxygen absorber-induced anoxia.

Multicellular tumor spheroids models are of increasing interest in preclinical studies and pharmacological evaluation. However, their storage and transport is often a limitation because it requires adapted and expensive procedures. Here, we propose a very simple method to store 3D spheroids, using a procedure based on oxygen absorber-induced anoxia. We report that oxygen absorbers allow generating an anoxic environment for spheroid storage in culture plates. Oxygen absorber-induced anoxia fully and reversibly arrests spheroid growth for 4 days at 37°C and up to 18 days at 4°C. We then show that the response to etoposide is comparable in spheroids preserved in conditions of absorber-induced anoxia at 4°C and spheroids kept in normoxia at 37°C. These results represent a major improvement that should simplify the storage, transport and use of 3D spheroids.

One Methylene Group in the Side Chain Can Alter by 90 Degrees the Orientation of a Main-Chain Liquid Crystal on a Unidirectional Substrate.

The mechanisms of orientation of columnar liquid crystals (LCs) on a PTFE-rubbed surface are explored on a homologous series of symmetrically substituted poly(di-n-alkylsiloxanes) (PDAS). It is shown that by increasing the side-chain length in steps of one CH2 group, the orientation of PDAS switches back and forth from perpendicular to parallel with respect to PTFE chains. These changes are sensitive to the smallest possible variation of the macromolecular structure (i.e., modification of the side chain length by just one CH2 group) reflect the alteration of the alignment mechanism identified as graphoepitaxial or epitaxial for the perpendicular and parallel orientation, respectively. The results show that two orthogonal LC orientations are realizable on the same rubbed substrate, which can open new perspectives in the field of organic and printed electronics such as multidomain LCD technology.

Solution-processable septithiophene monolayer transistor.

Septithiophene with endgroups designed to form liquid crystalline phases and allows controlled deposition of an electrically connected monolayer. Field effect mobilies mobilities of charge carriers and spectroscopic properties of the monolayer provide evidence of sustainable transport and delocalization of the excitation through intermolecular interactions within the layer.