Heteroatom doping is an effective way to adjust the fluorescent properties of carbon quantum dots. However, selenium-doped carbon dots have rarely been reported, even though selenium has unique chemical properties such as redox-responsive properties owing to its special electronegativity. Herein, a facile and high-output strategy to fabricate selenium-doped carbon quantum dots (Se-CQDs) with green fluorescence (quantum yield 7.6 %) is developed through the hydrothermal treatment of selenocystine under mild conditions. Selenium heteroatoms endow the Se-CQDs with redox-dependent reversible fluorescence. Furthermore, free radicals such as OH can be effectively scavenged by the Se-CQDs. Once Se-CQDs are internalized into cells, harmful high levels of reactive oxygen species (ROS) in the cells are decreased. This property makes the Se-CQDs capable of protecting biosystems from oxidative stress.

Selenium is a semimetallic element lying in group XVI of the periodic table with its chemical properties resembling sulfur. But owing to its relatively low electronegativity and large atomic radius compared with sulfur, selenium also shows unique properties. This feature endows selenium-containing compounds with high reactivity and sensitivity. Although organic selenium chemistry has been developing very fast, the successful introduction of selenium into polymer science is rather scarce. Fortunately, we have seen a drastic rising trend in the area of selenium-containing polymers over the past decade. In this Perspective, the synthetic routes of selenium-containing polymers are summarized, and their unique stimuli-responsive properties are elaborated on, together with their diverse applications in the field of adaptive and biomedical materials.

The application of selenium in the responsive polymer system and the enzyme mimic system have been well studied. Our group initiated this line of research in 2009 by first extending selenium chemistry to dynamic chemistry. In this article, the discovery, progress, and application of selenium-related dynamic covalent bonds will be introduced. The dynamic property of Se−N bond and Se−Se bond were revealed and have been applied in the polymer system as enzyme mimic and selfhealing materials, respectively. Further studies that need to be done and potential application of selenium-related dynamic chemistry will also be discussed.

Heteroatom doping is an effective way to adjust the fluorescent properties of carbon quantum dots. However, selenium‐doped carbon dots have rarely been reported, even though selenium has unique chemical properties such as redox‐responsive properties owing to its special electronegativity. Herein, a facile and high‐output strategy to fabricate selenium‐doped carbon quantum dots (Se‐CQDs) with green fluorescence (quantum yield 7.6 %) is developed through the hydrothermal treatment of selenocystine under mild conditions. Selenium heteroatoms endow the Se‐CQDs with redox‐dependent reversible fluorescence. Furthermore, free radicals such as .OH can be effectively scavenged by the Se‐CQDs. Once Se‐CQDs are internalized into cells, harmful high levels of reactive oxygen species (ROS) in the cells are decreased. This property makes the Se‐CQDs capable of protecting biosystems from oxidative stress.

Surface modification is an important techniquei n fields,s uch as,s elf-cleaning,s urface patterning, sensing, and detection. The diselenide bond was shown to be ad ynamic covalent bond that can undergo ad iselenide metathesis reaction simply under visible light irradiation. Herein we develop this diselenide dynamic chemistry into av ersatile surface modification method with af ast response and reversibility.T he diselenide bond could be modified onto various substrates,s uch as,P DMS,q uartz, and ITOc onductive film glass.D ifferent functional diselenide molecules could then be immobilized onto the surface via diselenide metathesis reaction. We demonstrated that by using this modification method we could achieve liquid motion in acapillary tube under light illumination. We also show that this approach has the potential to serve as an efficient modification method for surface bioconjugation, whichh as practical applications in clinical usage.