Photostability of quantum dots with amphiphilic polymer-based passivation strategies

Abstract

Quantum dots (QDs) have many appealing properties for biological fluorescence imaging,but exhibit photostabilities that are dependent upon surface passivation to minimizesusceptibility to oxygen and light. Here, through spectroscopy and imaging techniques, wecompare the photostability of micelle-encapsulated QDs with QDs passivated with eithercrosslinked amphiphilic polymers or crosslink-free amphiphilic polymers. Both crosslinkedand crosslink-free amphiphilic polymer passivation strategies produced QDs with highphotoluminescence stability for exposure to light under ambient conditions. Incontrast, micelle encapsulation resulted in QDs with photoluminescence emissionlevels that were highly sensitive to both light exposure and oxygen, exhibiting areduction of up to 70% in photoluminescence intensity within twenty minutesof exposure. With the addition of reducing agents, the photoluminescence levelof the micelle-encapsulated QDs was significantly stabilized. We conclude thatamphiphilic polymers provide coatings with considerably higher integrity andstability than micelle encapsulation, reducing the QDs’ sensitivities to oxygenand light, both of which are relevant factors in biological imaging applications.