Central retinal artery occlusion (CRAO) is an obstruction of the retinal artery carrying oxygen to the cells in the inner retinal layers. This lack of oxygen may result in irreversible loss of sight if not treated within 24−36 h. We propose a dextranbased oxygen nanobubble (DONB) platform for intravitreal delivery of oxygen to rescue the inner retina from such ischemic damage. The size distribution of DONBs was 119.6 ± 44.9 nm and the zeta (ζ)-potential was −35.54 ± 10.54 mV. The DONBs were found to be stable in amber vials at 5 ± 3 °C for over 4 months and the formulation was not cytotoxic. The therapeutic efficacy of DONBs was first evaluated in retinal precursor cell lines which showed excellent recovery and then in a hypoxia/reperfusion rat eye model. Oxygen distribution measurements and histology indicated excellent recovery of the ganglion and inner retinal cell layers. Electroretinography exhibited normal retinal function. Our unique approach suggests a promising pathway to treat CRAO, a blinding condition for which no effective treatment exists.

We disclose for the first time a facile synthetic methodology for the preparation of multicolor carbon dots (CDs) from a single source barring any chromatographic separations. This was achieved via sequential intraparticle cross-linking of surface abundant carboxylic acid groups on the CDs synthesized from a precursor to control their photoluminescence (PL) spectra as well as affect their degree of cellular internalization in cancer cells. The change in PL spectra with sequential cross-linking was projected by theoretical density functional theory (DFT) studies and validated by multiple characterization tools such as X-ray photoelectron spectroscopy (XPS), PL spectroscopy, ninhydrin assay, etc. The variation in cellular internalization of these cross-linked CDs was demonstrated using inhibitor assays, confocal microscopy, and flow cytometry. We supplemented our findings with high-resolution dark-field imaging to visualize and confirm the colocalization of these CDs into distinct intracellular compartments. Finally, to prove the surface-state controlled PL mechanisms of these cross-linked CDs, we fabricated a triple-channel sensor array for the identification of different analytes including metal ions and biologically relevant proteins.

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