A block copolymer with diselenide bonds in the polymer backbone was reported. This block copolymer was capable of forming micellar aggregates that were responsive to redox stimuli. Compared with other redox responsive aggregates, this type of diselenide-containing block copolymer aggregates could be responsive to both oxidants and reductants even in a solution with a very low concentration under mild conditions.

Although researchers have made great progress in the development of responsive polymeric materials for controlled drug release or diagnostics over the last 10 years, therapeutic results still lag behind expectations. The development of special materials that respond to physiological relevant concentrations, typically within the micromolar or nanomolar concentration regime, remains challenging. Therefore, researchers continue to pursue new biomaterials with unique properties and that respond to mild biochemical signals or biomarkers. Selenium is an essential element in human body with potential antioxidant properties. Because of selenium's electronegativity and atomic radius, selenium-containing compounds exhibit unique bond energy (C-Se bond 244 kJ mol⁻¹; Se-Se bond 172 kJ mol⁻¹). These values give the C-Se or Se-Se covalent bonds dynamic character and make them responsive to mild stimuli. Therefore, selenium-containing polymers can disassemble in response to changes under physiological relevant conditions. This property makes them a promising biomaterial for controlled release of drugs or synthetic enzyme mimics. Until recently, few researchers have looked at selenium-containing polymers as novel biomaterials. In this Account, we summarize our recent research on selenium-containing polymers and show their potential application as mild-responsive drug delivery vehicles and artificial enzymes. We begin by reviewing the current state of the art in the synthesis of selenium-containing main chain block copolymers. We highlight the dual redox and gamma-irradiation behaviors of diselenide-containing block copolymers assemblies, discussing the possibility of their use in a combination of chemotherapy and actinotherapy. We also describe the coordination of platinum with monoselenide containing block copolymers. Such structures offer the possibility of fabricating multidrug systems for cooperative chemotherapy. In addition, we summarize the methods for the covalent and noncovalent preparation of selenium-containing polymers with side chains, which highlight the opportunity to reversibly tune the amphiphilicity of selenium-containing polymers. Finally, we present strategies for the design of highly efficient selenium-containing dendritic polymers that can mimic enzymes. This field is still in its infancy period, and further research can only be limited by our imagination.

Amphiphilicity is one of the molecular bases for self‐assembly. By tuning the amphiphilicity of building blocks, controllable self‐assembly can be realized. This article reviews different routes for tuning amphiphilicity and discusses different possibilities for self‐assembly and disassembly in a controlled manner. In general, this includes irreversible and reversible routes. The irreversible routes concern irreversible reactions taking place on the building blocks and changing their molecular amphiphilicity. The building blocks are then able to self‐assemble to form different supramolecular structures, but cannot remain stable upon loss of amphiphilicity. Compared to the irreversible routes, the reversible routes are more attractive due to the good control over the assembly and disassembly of the supramolecular structure formed via tuning of the amphiphilicity. These routes involve reversible chemical reactions and supramolecular approaches, and different external stimuli can be used to trigger reversible changes of amphiphilicity, including light, redox, pH, and enzymes. It is anticipated that this line of research can lead to the fabrication of new functional supramolecular assemblies and materials.

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Visible light is an easily achievable and mild trigger for self-healing materials. By incorporating dynamic diselenide bonds into polyurethane, visible-light-induced self-healing materials can be fabricated. Besides mild visible light, the healing process can also be realized using directional laser irradiation, which makes the system a remotely controllable self-healing system.