![]() CdSe xS 1−x/ZnSe yS 1−y alloy shells were grown gradationally onto the surface of a CdSe core, thus reducing the degree of lattice mismatch of the QDs due to the gradient conformation structure. fabricated CdSe-derived core/shell gradient alloy QDs, which had a QY of ca. The QY of the fabricated QDs increased to 85% after the encapsulation of the ZnS shell, and it decreased as the thickness of the ZnS shell increased. QDs with a CdZnSeS/ZnS core–shell structure were fabricated with various thicknesses of ZnS, and their photochemical properties were analyzed. They could also be used for in vitro fluorescence imaging. The fabricated QDs had a satisfactory QY (48%) and low cytotoxicity. reported the fabrication and application of core/multi-shell QDs that had an alloy-typed core. To address this limitation, several researchers focused on novel alloy-typed QDs instead of conventional multi-layer QDs. Thus, low QY has been a major drawback of QDs, which limits their bio-application. However, the quantum yield (QY), an important performance index, of QDs has been reported to decrease during the surface modification step. Therefore, several studies have attempted to modify the surface of QDs for bio-imaging applications. Although these ligands enhance the stability of QDs in hydrophobic environments such as toluene or n-hexane, QDs with these ligands cannot be used for bio-imaging because they easily aggregate in such physiological conditions due to the hydrophobicity of the ligands. ĭuring QD fabrication, their surface is surrounded with ligands such as trioctylphosphine (TOP) or trioctylphosphine oxide (TOPO). Therefore, QDs have been used as an alternative to fluorophores in various fields, particularly in bio-imaging. ![]() Furthermore, the photo-stability of QDs is higher than that of traditional fluorophores. The maximum wavelength of the emitted light depends on the size of the QDs and can be easily adjusted by controlling the QD size. QDs can absorb a wide range of light wavelengths and emit light with a narrower bandwidth than that of organic fluorophores. Quantum dots (QDs) are semiconductor nanocrystals that have unique optical properties depending on their nanoscale size. And also, alloy QDs showed the potential as nanoprobes for highly sensitive bioimaging analysis. The alloy QDs maintained a higher QY in hydrophilization for biological applications than MQDs. The alloy QDs exhibited a stronger fluorescence signal than MQD these signals were retained in the popliteal lymph node area for 24 h. Alloy QDs and MQDs, after conjugation with FA, were successfully used for targeting human KB cells. The QY was 77.8% after the alloy QDs were conjugated with folic acid (FA). After hydrophilic surface modification, the alloy QDs exhibited a QY of 84.7%, which is 1.5 times higher than that of MQDs. The alloy QDs exhibited strong fluorescence and a high QY of 98.0%. The structure of the alloy QDs was confirmed using time-of-flight medium-energy ion scattering spectroscopy. 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). 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. 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.
0 Comments
Leave a Reply. |