**6. Assembly of cell-based structures in vivo by OFTs**

The assembly capability can also be used for in vivo applications. For example, a non-contact intracellular binding and controllable manipulation of chloroplasts *in vivo* was demonstrated using OFTs [12]. By launching a laser beam at 980 nm wavelength into the tapered fiber, which was placed above the surface of a living plant (*Hydrilla verticillata*) leaf with a gap of about 3 μm to the leaf surface, chloroplasts with different numbers were stably bound and arranged into one-dimensional chains and two-dimensional arrays inside the leaf by optical force without damage to the chloroplasts, by the cooperation of scattering force *F*s and gradient force *F*<sup>g</sup> (**Figure 7**). The formed chloroplast chains were controllably transported inside the living cells. This non-invasive and non-contact method of organelle binding and manipulation could provide a way for biological and biochemical research *in vivo*, especially for investigating signal transduction and communication between intracellular organelles via organized organelle-organelle contact.

#### **Figure 7.**

*Assembly of biophotonic probes in vivo [12]. (a) Schematic illustration of biophotonic probe assembly inside a leaf using OFTs. (b) Schematic illustration of biophotonic probe assembly based on a chain of chloroplasts. The chloroplasts inside a leaf are trapped and assembled by the cooperation of Fg and Fs. (c) Schematics and microscope images of the manipulation and assembly of organelle-based biophotonic probes in vivo.*
