Synthesis, characterization and cytotoxicity of polyethylene glycol-encapsulated CdTe quantum dots

Abstract

Semiconductor quantum dots (QDs) offer tremendous scope to be used in the field of energy, imaging, sensors and optoelectronic devices. However, several issues regarding their hydrophilicity, stability and cytotoxicity remain unresolved. One of the methods to render CdTe QDs water-soluble is to functionalize the surface with carboxylate groups by the use of heterobifunctional ligands such as 3-mercaptopropionic acid (MPA). Following this motif, we report the synthesis of CdTe QDs using the non-aqueous organometallic route, ligand exchange with MPA was performed to replace the initial surface passivation ligands trioctylphosphine oxide (TOPO) and hexadecylamine, and finally, the prepared MPA-CdTe QDs were encapsulated into the biocompatible polyethylene glycol. Our results show that pegylation of CdTe QDs provided minimal cytotoxicity against baby hamster kidney (BHK 21) cells even at high levels. The IC 50 values of pegylated CdTe QDs were higher than the non-pegylated ones with a % viability ranges from 89:90% at a concentration range of 0.01:0.03 nM. Currently, available ligand exchange procedures lead to significant loss of quantum yields. In our study, the photoluminescence (PL) emission of the MPA capped CdTe QDs decreased gradually as the pH increased from 4 to 10 while after pegylation the prepared QDs exhibited significantly enhanced PL efficiency and storage stability.

Research advance on cell imaging and cytotoxicity of different types of quantum Dots

“…At present, the concentration of QDs is determined by many ways: (1) quantifying a specific element of QDs to determine the concentration (For example, using Cd element to quantify the concentration of CdTe QD) (He et al, 2018; Wu, Liang, He, Wei, Wang, Zou, et al, 2018); (2) weighing the mass of freeze‐dried powder of QDs (especially carbon‐based QDs) (Murugan et al, 2017; Singh et al, 2012); (3) measuring the absorbance and using Beer's Law to calculate the molar concentration (Ali et al, 2019; Han et al, 2019). In addition, QDs are atomic clusters composed of a variety of elements, and they are not fixed, single and pure compounds.…”

Quantum dots as targeted doxorubicin drug delivery nanosystems in human lung cancer cells

“…Covalent functionalization of silicon QDs with phenanthrene, pyrene, and perylene chromophores (Abdelhameed et al 2018) effectively tuned the emission color as well as enhanced the emission quantum efficiency. In order to enhance their water solubility and thus biocompatibility, QDs can be coated with hydrophilic ligands (such as thiolate alcohols, thiolate acids and thiolate siloxane acids (Zhou et al 2017), or monothiol ligands including 3-mercaptopropionic acid (MPA) (Ali et al 2019) and mercaptoundecanoic (MUA)), amphiphilic polymers (such as polyethylene glycol (Susumu et al 2009), poly(N-isopropylacrylamide) (Hu and Gao 2010)), or silica (Cao et al 2020;Hu and Gao 2010). Besides these, glutathione (Aydemir et al 2020), bovine serum albumin (Barba-Vicente et al 2020;Sahoo et al 2019), poly(lactic-co-glycolic acids), and chitosan (Kharkar et al 2020) were also reported to promote the biocompatibility of QDs.…”

Smart Nanoparticles in Biomedicine: An Overview of Recent Developments and Applications

“…QDs potential toxicity can also be limited by surface modification, like adding PEG [86] or carbohydrate to QDs [87], [88]. In this contest, recently, cadmium-free QDs (Cd-free QDs) made of indium/palladium were amply used because of their higher biocompatibility [89], [90].…”