Abstract
Quantum dots have been considered to be promising candidates for bioapplications because of their high sensitivity, rapid response, and reliability. The synthesis of high-quality quantum dots that can be dissolved in water and other biological media is a crucial step toward their further application in biology. Starting with a one-pot reaction and the successive ionic layer adsorption and reaction (SILAR) method, we produced the CdSe/ZnS core/shell structure. Through a ligand-exchange mechanism, we coated the as-made CdSe/ZnS structure with 3-mercaptopropionic acid (MPA) or mercaptosuccinic acid (MSA). Various techniques, including photoluminescence (PL), ultraviolet-visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy, were utilized to characterize the ligand-coated CdSe/ZnS structure. The results show enhanced luminescence intensity, CdSe surface passivation by ZnS, and successful coating with MPA and MSA. The stability of quantum dots in solutions with different pH values was investigated by performing zeta potential measurements. The results revealed that the quantum dots shifted from displaying hydrophobic to hydrophilic behavior and could be connected with bioagents.
Highlights
Semiconducting quantum dots have been extensively studied in recent decades because of their unique physical characteristics, which are superior to those of their bulk and thin-film counterparts
We present the synthesis and characterization of the CdSe/ZnS core/shell structure and the functionalization of its surface with mercaptopropionic acid (MPA) and mercaptosuccinic acid (MSA)
The properties of the synthesized quantum dots were characterized by absorption and PL spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR), and transmission electron microscopy (TEM)
Summary
Semiconducting quantum dots have been extensively studied in recent decades because of their unique physical characteristics, which are superior to those of their bulk and thin-film counterparts. CdSe quantum dots have been intensely investigated and applied in many different fields, including display devices, quantum dot solar cells, quantum dot lasers, and biological applications Because of their high photostability, low photobleaching speed, and strong photoluminescence (PL) under illumination, they have great potential to replace the currently used organic dyes and are good candidate materials for biomedical applications. The problems of unstable organic cover layers and low quantum dot surface coverage (approximately 40– 60%) must be overcome [4]. Because of these issues, abundant defects exist at the surface that decreases the dot luminescence efficiency. This, in turn, enhances the dots chemical stability and luminescence efficiency
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