The interactions of CdTe quantum dots with serum albumin and subsequent cytotoxicity: the influence of homologous ligands

Abstract

With spreading applications of fluorescent quantum dots (QDs) in biomedical fields in recent years, there is increasing concern over their toxicity. Among various factors, surface ligands play critical roles. Previous studies usually employed QDs with different kinds of surface ligands, but general principles were difficult to be obtained since it was hard to compare these surface ligands with varied chemical structures without common features. Herein, the physicochemical properties of two types of CdTe QDs were kept very similar, but different in the surface ligands with mercaptoacetic acid (TGA) and 3-mercaptopropionic acid (MPA), respectively. These two types of homologous ligands only had a difference in one methylene group (-CH-). The interactions of the two types of CdTe QDs with bovine serum albumin (BSA), which was one of the main components of cell culture, were studied by fluorescence, UV-vis absorption, and circular dichroism spectroscopy. It was found that the fluorescence quenching of BSA by CdTe QDs followed a static quenching mechanism, and there was no obvious difference in the Stern-Volmer quenching constants and binding constants. The thermodynamic parameters of the two types of QDs were similar. BSA underwent conformational changes upon association with these QDs. By comparing the cytotoxicity of these two types of QDs, TGA-capped QDs were found to be less cytotoxic than MPA-capped QDs. Besides, in the presence of serum proteins, the cytotoxicity of the QDs was reduced. QDs in the absence of serum proteins had a higher internalization efficiency, compared with those in the medium with serum. To the best of our knowledge, this is a rare study focusing on surface ligands with such small variations at the biomolecular and cellular levels. These findings can provide new insights for the design and applications of QDs in complex biological media.

Thermodynamic Implications and Time Evolution of the Interactions of Near-Infrared PbS Quantum Dots with Human Serum Albumin

“…To date, some studies have reported the interactions between proteins and nanoparticles, such as carbon dots, nanoclusters, , magnetic nanoparticles, and quantum dots. − These articles used various methods, including fluorescence spectroscopy, UV–vis spectroscopy, electrochemistry, etc., to study the process in depth to obtain driving forces, structural influences, and the thermodynamic parameters, which can explain in principle the interactions. These studies found that the interactions depended on surface ligands, ,, surface charges, and particle sizes .…”

“…To date, some studies have reported the interactions between proteins and nanoparticles, such as carbon dots, nanoclusters, , magnetic nanoparticles, and quantum dots. − These articles used various methods, including fluorescence spectroscopy, UV–vis spectroscopy, electrochemistry, etc., to study the process in depth to obtain driving forces, structural influences, and the thermodynamic parameters, which can explain in principle the interactions. These studies found that the interactions depended on surface ligands, ,, surface charges, and particle sizes . Recently, we briefly summarized the interactions of QDs with proteins .…”

Binding of Water‐Soluble CdSe Quantum Dots with Human Serum Albumin: Further Studies into their Effects on Dietary Polyphenol Binding and Sensing of Antibiotic Lomefloxacin

“…Various groups across the world have reported many literatures in this context. [20][21][22]32,33] In this paper we choose the HSA (the most abundant protein present in blood plasma) as biological target for studying the toxic effect of CdSe QDs. Interactions of dietary polyphenols with HSA have been extensively studied to improve the binding affinity, site specific drug delivery and drug potency.…”

Nano-Bio Interaction between Blood Plasma Proteins and Water-Soluble Silicon Quantum Dots with Enabled Cellular Uptake and Minimal Cytotoxicity

“…As an alternative, researchers choose semiconductor quantum dots (QDs) because of their high quantum yield and low photobleaching characters. Previously studied QDs that exhibit a molecular interaction with proteins consist of toxic heavy metal ions, such as cadmium, lead, selenium, or mercury [ 9 , 10 , 11 ].…”