<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "Towards photoacoustic neuroimaging in mice: \r\na chemigenetic approach for acoustogenic calcium sensors"^^ . "Photoacoustic imaging is an attractive imaging modality for in vivo applications such as neuroimaging, able to \r\nimage large fields of view, deep in tissue, at high resolution. However, robust molecular reporters are required \r\nfor this modality, to label specific targets of interest and visualise dynamic biochemical events. Various \r\ngenetically-encoded or synthetic reporters have been implemented, but suffer from poor optical properties or \r\nlack of labelling specificity. Here, we report the development of novel “chemigenetic” contrast agents and \r\ncalcium sensors for photoacoustic imaging, based on synthetic dyes and the self-labelling HaloTag protein.\r\nI designed and synthesised new photoacoustic reporters based on quenched near-infrared rhodamine-like\r\nderivatives, tailored for use with HaloTag to exploit the open-closed equilibrium of the lactone ring. These were \r\ncharacterised in vitro for high photoacoustic signal and turn-on upon binding to HaloTag. The most promising \r\nligands were used for the design of calcium indicators, with the HaloTag-based HaloCaMP protein, which show \r\nan absorption-modulated change in calcium-dependent photoacoustic signal. Cell permeability of these ligands \r\nwas confirmed by efficient labelling of live cells cytosolically expressing HaloTag. Our resulting \r\n“acoustogenic” calcium sensors show large turn-ons in response to calcium, up to 8-fold, high photoacoustic \r\nsignal and photostability, outperforming existing far-red sensors for this modality such as NIR-GECO1 in \r\ntissue-mimicking phantoms. Ex vivo brain slices with neuronal expression of HaloTag, labelled with our ligands, \r\ncould be consistently visualised via photoacoustic tomography. In vivo labelling experiments in mice, however, \r\nshowed mixed results with the occasional specific labelling of HaloTag-expressing neurons suggesting that the \r\nbioavailability of our ligands needs to be improved.\r\nIn summary, we developed a novel approach for the design of photoacoustic reporters, with the first \r\nchemigenetic probes for this modality. Our acoustogenic dyes and first-generation photoacoustic calcium \r\nsensors, show superior in vitro performance to existing sensors, and we can label mice brain tissues to produce \r\na localised, strong PA signal. To reach our long-term goal of whole-brain neuroimaging in mice, we have started \r\nprotein engineering to improve the dynamic range, calcium binding affinity, and used established methods to \r\nassess dye bioavailability to optimise this key parameter for future in vivo applications. In general, with this \r\nhybrid design, we hope to stimulate photoacoustic probe and sensor development which can enable this \r\npowerful modality to uncover its true potential in the field of neuroimaging and beyond."^^ . "2025" . . . . . . . "Alexander Stratford"^^ . "Cook"^^ . "Alexander Stratford Cook"^^ . . . . . . "Towards photoacoustic neuroimaging in mice: \r\na chemigenetic approach for acoustogenic calcium sensors (PDF)"^^ . . . "Alexander_Cook_PhD_thesis_final.pdf"^^ . . . "Towards photoacoustic neuroimaging in mice: \r\na chemigenetic approach for acoustogenic calcium sensors (Other)"^^ . . . . . . "lightbox.jpg"^^ . . . "Towards photoacoustic neuroimaging in mice: \r\na chemigenetic approach for acoustogenic calcium sensors (Other)"^^ . . . . . . "preview.jpg"^^ . . . "Towards photoacoustic neuroimaging in mice: \r\na chemigenetic approach for acoustogenic calcium sensors (Other)"^^ . . . . . . "medium.jpg"^^ . . . "Towards photoacoustic neuroimaging in mice: \r\na chemigenetic approach for acoustogenic calcium sensors (Other)"^^ . . . . . . "small.jpg"^^ . . . "Towards photoacoustic neuroimaging in mice: \r\na chemigenetic approach for acoustogenic calcium sensors (Other)"^^ . . . . . . "indexcodes.txt"^^ . . "HTML Summary of #35912 \n\nTowards photoacoustic neuroimaging in mice: \na chemigenetic approach for acoustogenic calcium sensors\n\n" . "text/html" . . . "500 Naturwissenschaften und Mathematik"@de . "500 Natural sciences and mathematics"@en . . . "540 Chemie"@de . "540 Chemistry and allied sciences"@en . . . "570 Biowissenschaften, Biologie"@de . "570 Life sciences"@en . .