High-quantum yield alloy-typed core/shell CdSeZnS/ZnS quantum dots for bio-applications

Abstract

Background Quantum dots (QDs) have been used as fluorophores in various imaging fields owing to their strong fluorescent intensity, high quantum yield (QY), and narrow emission bandwidth. However, the application of QDs to bio-imaging is limited because the QY of QDs decreases substantially during the surface modification step for bio-application. Results In this study, we fabricated alloy-typed core/shell CdSeZnS/ZnS quantum dots (alloy QDs) that showed higher quantum yield and stability during the surface modification for hydrophilization compared with conventional CdSe/CdS/ZnS multilayer quantum dots (MQDs). The structure of the alloy QDs was confirmed using time-of-flight medium-energy ion scattering spectroscopy. The alloy QDs exhibited strong fluorescence and a high QY of 98.0%. After hydrophilic surface modification, the alloy QDs exhibited a QY of 84.7%, which is 1.5 times higher than that of MQDs. The QY was 77.8% after the alloy QDs were conjugated with folic acid (FA). Alloy QDs and MQDs, after conjugation with FA, were successfully used for targeting human KB cells. The alloy QDs exhibited a stronger fluorescence signal than MQD; these signals were retained in the popliteal lymph node area for 24 h. Conclusion The alloy QDs maintained a higher QY in hydrophilization for biological applications than MQDs. And also, alloy QDs showed the potential as nanoprobes for highly sensitive bioimaging analysis. Graphical Abstract

Ultrafast dynamics and ultrasensitive single particle spectroscopy of optically robust core/alloy shell semiconductor quantum dots

“…Recently a new “one-pot one-step” synthesis method has been developed by Seonghoon Lee et al which produces an alloy-shelling over the core QDs (Scheme 2b). 55 This “one-pot one-step” “hot injection” alloy shell synthesis approach 55–86 offers a multitude of advantages, e.g. (i) the desired scope of large scale synthesis of QDs in a reproducible and economical manner.…”

Highly Luminescent Positively Charged Quantum Dots Interacting with Proteins and Cells†

“…For bioimaging and biosensing applications, this capping layer must be exchanged with a hydrophilic layer that confers colloidal stability in aqueous solvent. [ 9 ] To this end, long‐chain, monovalent or multivalent thiol reagents, carrying a charged moiety at the ω‐position for electrostatic stabilization of the QD in aqueous solvent, are frequently employed. Many studies have been performed to understand the intriguing charge trapping effects of the capping layer, which can greatly affect the photoluminescence (PL) properties.…”

“…Many studies have been performed to understand the intriguing charge trapping effects of the capping layer, which can greatly affect the photoluminescence (PL) properties. [ 9‐11 ] In biological applications, hydrophilic QDs are often exposed to biofluids of an organism, e.g ., by injection, ingestion or dermal exposure. [ 12‐13 ] Biomolecules (especially proteins) in those fluids interact with the capping layer, forming a biomolecular adsorption layer, the so‐called “protein corona”.…”

Highly bright silica-coated InP/ZnS quantum dot-embedded silica nanoparticles as biocompatible nanoprobes

“…[18,19] Although, InP/ZnS QDs possess the potential to be used in biological applications, [20,21] compared to the well-developed CdSe-based QDs, these still have lower brightness, which limits the direct application of single InP/ZnS QDs to bioimaging. [22][23][24] To overcome the low brightness of single QDs, approaches for embedding multiple QDs onto the surface of a silica template structure have been leveraged. [25][26][27] As the fabricated silica template-based multi-QDs are brighter than single QDs, they could be used as advanced strategies for applying QDs in biological elds.…”