The unique physical properties of single-wall carbon nanotubes (SWCNTs) have been exploited in novel applications in various fields including electronics and life sciences. Their photoluminescence in the near-infrared (NIR) range, where optical interference from biological tissues is minimum, has rendered them particularly attractive as optical probes in biological environments. Herein we review the use of the SWCNT NIR emission in bio-sensing and imaging.To interface the insoluble carbon nanotubes with aqueous biological environment, biomaterials and organic polymers have been widely used for non-covalently functionalizing SWCNTs. Such functionalization minimizes the toxicity of carbon nanotubes in biological and physiological environments, while maintaining its optical properties. SWCNTs have been demonstrated as both in vitro and in vivo optical sensors, targeting biologically important molecules, such as neurotransmitters and cell signaling molecules. For optical imaging, functionalized SWCNTs were used as NIR contrast agents for probing cellular processes and imaging plants and small animals.We also discuss emerging SWCNT-based super-resolution schemes. We conclude that SWCNTs are promising optical materials for basic life science research, biomedical diagnostics, and therapeutics.

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Super-resolution imaging reveals the stochastic behavior of DNA walkers.

Chemotactic cell motility plays a critical role in many biological functions, such as immune response and embryogenesis. Constructing synthetic cell-mimicking systems, such as a dynamic protocell, likewise requires molecular mechanisms that respond to environmental stimuli and execute programmed motility behaviors. Although various molecular components were proposed to achieve diverse functions in synthetic protocells, chemotactic motility on surfaces has not been reported thus far. Here we show directional motility in synthetic lipid vesicles capable of chasing each other by programming DNA components. We demonstrate that the “follow” vesicle recognizes and migrates along the moving trajectory of the “lead” vesicle with an enhanced speed, thus mimicking natural chemotaxis in cell migration. This work provides new possibilities for building synthetic protocells with complex functions such as programmed morphogenesis and cooperative motion. With the vast library of dynamic DNA components, we envision that this platform will enable new discoveries in fundamental sciences and novel applications in biotechnology.

Here we design a DNA origami-based site-specific molecular capture and release platform operated by a DNAzyme-mediated logic gate process. We show the programmability and versatility of this platform with small molecules, proteins, and nanoparticles, which may also be controlled by external light signals.