Monolayer Silane‐Coated, Water‐Soluble Quantum Dots

Abstract

A one-step method to produce ≈12 nm hydrodynamic diameter water-soluble CdSe/ZnS quantum dots (QDs), as well as CdS/ZnS, ZnSe/ZnMnS/ZnS, AgInS2 /ZnS, and CuInS2 /ZnS QDs, by ligand exchange with a near-monolayer of organosilane caps is reported. The method cross-links the surface-bound silane ligands such that the samples are stable on the order of months under ambient conditions. Furthermore, the samples may retain a high quantum yield (60%) over this time. Several methods to functionalize aqueous QD dispersions with proteins and fluorescent dyes have been developed with reaction yields as high as 97%.

Quantum dot surface engineering: Toward inert fluorophores with compact size and bright, stable emission

“…Amorphous silica (SiO 2 ) has been widely used to provide highly crosslinked shells on nanocrystals that yield stable products, coated directly through oxide coordination or via ligand anchoring groups [238]. However despite nearly 20 years of reports, silica-coated QDs have not been widely adopted due to the difficulty in generating shells less than ~5 nm due to complex and unpredictable nature of silane chemistry [239-241]. …”

Stable, small, specific, low-valency quantum dots for single-molecule imaging

“…This extended uncleavable flexible linker provided the space and flexibility for subsequent QD labeling. 16 APCs were pulsed with 50 nM of biotin-MCC peptides. 47 The peptide-pulsed APCs were washed five times using cold PBS supplemented with 2% BSA and 0.05% NaN 3 (to prevent any possible internalization or export of MHC), resuspended in 1 mL of the same medium and labeled with mSA-QD conjugates at 4°C for 30 minutes.…”

“…5–7 Quantum dots (QDs), which are semiconductor nanoparticles, have been used widely to complement conventional organic dyes and fluorescent proteins due to their photostability, brightness, broad absorption, and narrow emission. 4–16 However, most immediately available QDs are large in size (~20-30 nm hydrodynamic diameter) 17–19 and incapable of precise, valency-controlled labeling of proteins of interest (POIs). Thus, the construct size and multivalency of labeling pose two major challenges when using QDs as fluorescent probes.…”

Release of Warfarin from Human Serum Albumin by Water‐soluble CdSe Nanotetrapods

“…[35][36][37] Water solubility of nanocrystals is a key requirement in their biological applications and catalysis in aqueous medium. [38][39][40] They find application in sensing analytes in aqueous medium. [41][42][43] Bright and stable water soluble QDs can be prepared by deposition of a monolayer of silane on QDs.…”

“…[44] This layer can be further functionalized with protein and fluorescent dyes. [39] Covalent coupling of ZnS-capped CdSe quantum dots through 3-MPA with proteins, nucleic acids and peptides has been achieved. [45] Noncovalent interactions have also been utilized to prepare bioconjugates of QDs with phospholipid block-copolymer micelles, [46] calixarenes [47] and proteins.…”