Biodegradable Luminescent Silicon Quantum Dots for Two Photon Imaging Applications

Abstract

2 Abstract Cadmium-and lead-based quantum dots are normally coated for biological applications, because their degradation may result in the release of toxic heavy metal ions. Here, we synthesize silicon quantum dots that are expected to biodegrade to non-toxic products. A chitosan coating is used to render the silicon quantum dots stable in storage conditions and biodegradable at physiological conditions. The applications of these particles are demonstrated in cellular imaging with single and two-photon excitation. These results open the door for a new generation of silicon quantum dots that may have a wide variety of applications derived from the flexibility of chitosan.

The Large-Scale Synthesis of Vinyl-Functionalized Silicon Quantum Dot and Its Application in Miniemulsion Polymerization

“…Probably, under acidic conditions, the surface carboxylate groups converted into carboxyl groups giving zero-charged particles that are unstable colloids. Finally, bioapplicability of SiQD@PS NPs was corroborated by their two-photon luminescence ability; the property endows excitation nanoprobes with long-wavelength light that is less scattered by tissues [28]. As shown in Figure 3(d), normalized PL spectra of SiQD@PS NPs were identical with either excitation wavelength at 320 nm or 640 nm.…”

“…The colloidal Si QDs with a hydrodynamic size in order of 10 nm may have fast distribution and urine clearance but they commonly exhibit luminescence blinking properties [23]. Surfactant-stabilized aggregates of QDs contain some QDs so as to give continuous emission being suitable for tracking applications [28]; their size is hardly controlled because it depends on the chemical structure of surfactant. Herein we encapsulated V-Si QDs into polystyrene NPs to not only prevent V-Si QDs from further oxidation, hence preserving their luminescence, but also produce biocompatible NPs whose hydrodynamic sizes could be controlled easily.…”