mcmahon probe

Cartoon showing nanoscale probe used to detect pH change caused by death of transplanted cell. (McMahon/Nature Materials)

a, The L-arginine (R) moieties (red) entrapped in liposomes (1) and in protamine (2) have exchangeable protons that provide CEST contrast. b, A mixture of cells, alginate and L-arginine liposomes is passed through a needle using a nanoinjector pump. The single-layered charged alginate droplets are collected, washed and resuspended in a crosslinker solution (protamine sulphate), followed by a coating with a second layer of alginate. c, Phase-contrast image (top) and fluorescent image (bottom; with NBD-PE (1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-(7-nitro-2-1,3-benzoxadiazol-4-yl))-labelled liposomes) showing a uniform distribution of cells and liposomes within the microcapsule. Scale bars, 200 μm.