Abstract
Quantum dots (QDs) as a promising optical probe have been widely used for in vivo biomedical imaging; especially enormous efforts recently have focused on the potential toxicity of QDs to the human body. The toxicological effects of the representative InP/ZnS QDs as a cadmium-free emitter are still in the early stage and have not been fully unveiled. In this study, the DPPC/DPPG mixed monolayer was used to simulate the lung surfactant monolayer. The InP/ZnS-COOH QDs and InP/ZnS-NH2 QDs were introduced to simulate the lung surfactant membrane’s environment in the presence of InP/ZnS QDs. The effects of InP/ZnS QDs on the surface behavior, elastic modulus, and stability of DPPC/DPPG mixed monolayer were explored by the surface pressure-mean molecular area isotherms and surface pressure-time curves. The images observed by Brewster angle microscope and atomic force microscope showed that the InP/ZnS QDs affected the morphology of the monolayer. The results further demonstrated that the InP/ZnS QDs coated with different surface groups can obviously adjust the mean molecular area, elastic modulus, stability, and microstructure of DPPC/DPPG mixed monolayer. Overall, this work provided useful information for in-depth understanding of the effects of the −COOH or −NH2 group coated InP/ZnS QDs on the surface of lung surfactant membrane, which will help scientists to further study the physiological toxicity of InP/ZnS QDs to lung health.
Highlights
Quantum dots (QDs) are one kind of the most classical quasi-zero dimensional and semiconductor nanocrystals, which have special optical properties: fluorescence, phosphorescence, and electrochemiluminescence (Bruchez et al, 1998; Namdari et al, 2017; Pohanka, 2017)
It has been suggested that the InP/ZnS QDs modified by the −COOH group caused the DPPC/DPPG mixed monolayer to be more condensed at the above-mentioned range of surface pressures, which was similar to that in the presence of the InP/ZnS QDs modified by the −NH2 group at the higher surface pressures
The InP/ZnS QDs modified by the −COOH group caused the DPPC/DPPG mixed monolayer to be more condensed, but the InP/ZnS QDs modified by the −NH2 group induced the mixed monolayer less condensed at the lower surface pressures
Summary
Quantum dots (QDs) are one kind of the most classical quasi-zero dimensional and semiconductor nanocrystals, which have special optical properties: fluorescence, phosphorescence, and electrochemiluminescence (Bruchez et al, 1998; Namdari et al, 2017; Pohanka, 2017). Chen et al have investigated the in vitro toxicity of InP/ZnS terminated with different surface groups (−COOH, −NH2, and −OH, respectively) on two lung-derived cell lines, human lung cancer cell HCC-15, and Alveolar epithelial type II (AEII) cell RLE-6TN (Chen et al, 2018). They found that the intake of InP/ZnS-OH QDs in the two types of cells was relatively lower than that of the InP/ZnS-COOH QDs and InP/ZnS-NH2 QDs. the uptake mechanism of the InP/ZnS QDs toward cell membrane has been not researched so far
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