Self-assembly of phosphorescent quantum dots/boronic-acid-substituted viologen nanohybrids based on photoinduced electron transfer for glucose detection in aqueous solution

Abstract

We synthesized boronic-acid-substituted viologens (BBV) and designed a glucose sensor based on room-temperature phosphorescence (RTP) quantum dots (QDs) and BBV. This sensor utilizes 3-mercaptopropionic acid (MPA)-capped Mn-doped ZnS QDs as an RTP indicator as well as BBV as an RTP quencher and a glucose detection receptor. At physiological pH 7.4, the negatively-charged MPA-capped Mn-doped ZnS QDs and the positively-charged BBV interact via electrostatic attraction to form composites, which quench the RTP of MPA-capped Mn-doped ZnS QDs via photoinduced electron transfer (PIET). After addition of glucose into this two-component system, it binds with boric acid to form a tetrahedral anionic borate, which effectively neutralizes the positive charge of BBV and deprives BBV from the QDs, thereby restoring the RTP. On this basis, this new sensor is built for glucose detection. This sensor has a detection limit of 0.09 mM and two linear ranges from 0 to 4 mM and from 4 to 16 mM, respectively. This sensor features enzyme independence, simple design and easy operation.