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Mapping of the metabolic activity of tumor tissues represents a fundamental approach to better identify the tumor type, elucidate metastatic mechanisms and support the development of targeted cancer therapies. The spatially resolved quantification of Warburg effect key metabolites, such as glucose and lactate, is essential. Miniaturized electrochemical biosensors scanned over cancer cells and tumor tissue to visualize the metabolic characteristics of a tumor is attractive but very challenging due to the limited oxygen availability in the hypoxic environments of tumors that impedes the reliable applicability of glucose oxidase-based glucose micro-biosensors. Herein, the development and application of a new glucose micro-biosensor is presented that can be reliably operated under hypoxic conditions. The micro-biosensor is fabricated in a one-step synthesis by entrapping during the electrochemically driven growth of a polymeric matrix on a platinum microelectrode glucose oxidase and a catalytically active Prussian blue type aggregate and mediator. The as-obtained functionalization improves significantly the sensitivity of the developed micro-biosensor for glucose detection under hypoxic conditions compared to normoxic conditions. By using the micro-biosensor as non-invasive sensing probe in Scanning Electrochemical Microscopy (SECM), the glucose uptake by a breast metastatic adenocarcinoma cell line, with an epithelial morphology, is measured., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The kinetics of flash-induced re-reduction of the Photosystem II (PS II) primary electron donor P 680 was studied in solution and in trehalose glassy matrices at different relative humidity. In solution, and in the re-dissolved glass, kinetics were dominated by two fast components with lifetimes in the range of 2-7 μs, which accounted for >85% of the decay. These components were ascribed to the direct electron transfer from the redox-active tyrosine Y Z to P 680 + . The minor slower components were due to charge recombination between the primary plastoquinone acceptor Q A - and P 680 + . Incorporation of the PS II complex into the trehalose glassy matrix and its successive dehydration caused a progressive increase in the lifetime of all kinetic phases, accompanied by an increase of the amplitudes of the slower phases at the expense of the faster phases. At 63% relative humidity the fast components contribution dropped to ~50%. A further dehydration of the trehalose glass did not change the lifetimes and contribution of the kinetic components. This effect was ascribed to the decrease of conformational mobility of the protein domain between Y Z and P 680 , which resulted in the inhibition of Y Z  → P 680 + electron transfer in about half of the PS II population, wherein the recombination between Q A - and P 680 + occurred. The data indicate that PS II binds a larger number of water molecules as compared to PS I complexes. We conclude that our data disprove the "water replacement" hypothesis of trehalose matrix biopreservation., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Cells of the facultative photosynthetic bacterium Rhodobacter capsulatus exploit the simultaneous presence in the cultural medium of the toxic oxyanion tellurite (TeO 3 2- ) and the redox mediator lawsone (2-hydroxy-1,4-naphthoquinone) by reducing tellurite to metal Te 0 nanoprecipitates (TeNPs) outside the cells. Here we have studied the mechanism by which lawsone interacts with metabolically active cells and analysed both structure and composition of the TeNPs collected from the growth medium of phototrophycally grown R. capsulatus. High Resolution Transmission Electron Microscopy (HR-TEM) images and Energy-Dispersive X-ray (EDX) microanalysis of TeNPs showed a central core of polycrystalline tellurium interspersed in an organic matrix with a predominant protein-based composition. The main proteins from Te 0 nanostructures were identified by Liquid Chromatography tandem-Mass Spectrometry and were all correlated with the cell outer membrane composition. The interaction of reduced lawsone with tellurite and with the bacterial cells was probed by Cyclic Voltammetry and Scanning ElectroChemical Microscopy (SECM). We concluded that lawsone is required for the reduction of tellurite to metal Te 0 in a reaction mechanism dependent on reducing equivalents deriving from the cell photosynthetic metabolism. SECM experiments demonstrate that lawsone, by diffusing inside the bacterial cells, is effectively available at the membrane site of the photosynthetic electron transport chain., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

An increasing number of publications report on the efficacy of trehalose in preserving organisms, cells, and macromolecules from adverse environmental conditions such as extreme temperatures and dryness. Although the mechanism by which this disaccharide exerts its protection is still debated, the implementation of trehalose as stabilizer is becoming a praxis in several preparative protocols from the pharmaceutical industry. We tested the ability of trehalose in protecting R-Phycoerythrin (R-PE), a pigment-protein complex widely used as fluorescent marker, from thermal denaturation. Once embedded into a dried trehalose matrix, R-PE retains its optical absorption-emission characteristics even when exposed to 70°C for h or when subjected to freeze-drying. We subsequently examined the protection exerted by trehalose on freeze-dried antihuman CD8-RPE (CD8-RPE) conjugated antibodies. Flow cytometric analysis showed that colyophilized trehalose-CD8-RPE preparations can be exposed for 4 weeks at 45°C without significant loss of functionality. Remarkably, even following 4 weeks incubation at 70°C, the preparations are still able to specifically recognize CD8(+) lymphocyte populations. These results show that colyophilization with trehalose makes possible the preparation of antibody-based diagnostic kits which can withstand breaks in the "cold chain" distribution, particularly suited for use in less-developed countries of the tropical areas., (Copyright © 2012 Wiley Periodicals, Inc.)