Photoresponsive Materials

Light provides high spatiotemporal resolution to precisely control properties and functions of materials. We synthesize new photoresponsive polymers and nanoparticles for biomedical applications, coatings, energy storages, self-healing and light-guided self-assembly. Our goal is to solve fundamental questions of photoresponsive materials, with the perspective of future applications. 

Figure 1. Properties of photoresponsive Ru complexes.

We are using Ru complexes as building blocks to construct photoresponsive polymers, surfaces and nanoparticles (Figure 1). Photoresponsive ruthenium complexes have some interesting features. First, ruthenium complexes are responsive to visible light. The responsive wavelength can be further red shifted to the NIR region by proper structure design. Second, the responsive coordination bond in Ru complexes can be used to construct reversible and dynamic systems. Third, some ruthenium complexes have anticancer activities, similar to the anticancer metallodrug cisplatin. Fourth, ruthenium complexes are singlet oxygen sensitizers, which are similar to drugs used in photodynamic therapy. These interesting features make ruthenium complexes have many potential applications.

Figure 2. Visible-light-induced photoisomerization of a polymer with tetra-ortho-methoxy-substituted azobenzene groups and reversible photopatterning.

We also use azobenzenes as building blocks to construct photoresponsive polymers, hydrogels and nanoparticles (Figure 2). Figure 2 shows an example: a visible light responsive azopolymer is applied to reversible photopatterning.

Upconverting nanoparticles are used as building blocks for near-infrared (NIR) light-responsive materials for biomedical applications (Figure 3).

Upconverting nanoparticles are building blocks to construct near-infrared (NIR) light-responsive materials. We combine upconverting nanoparticles and conventional photosensitive compound to construct NIR-responsive materials, which are useful in deep-tissue biomedical applications (Figure 3).

Based on photoswitchable azobenzene or Ru complexes we construct photoresponsive polymers and supramolecules. We control glass transition temperatures, adhesion, phase transitions, colors, morphologies, etc. with light. Upconverting nanoparticles allow us to construct near-infrared (NIR) light-responsive materials that are useful for deep-tissue biomedical applications. more
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