Nonspecific Adsorption of Charged Quantum Dots on Supported Zwitterionic Lipid Bilayers: Real-Time Monitoring by Quartz Crystal Microbalance with Dissipation

Abstract

Understanding how the composition and environmental conditions of membranes influence their interactions with guest species is central to cell biology and biomedicine. We herein study the nonspecific adsorption of charged quantum dots (QDs) onto a supported zwitterionic lipid bilayer by using quartz crystal microbalance with dissipation (QCM-D). It is demonstrated that (1) the adsorption of charged QDs is charge-dependent in a way similar to but much stronger than that of the capping molecules by reason of size effect; (2) the adsorption behavior of charged QDs is dominated by electrostatic interaction, which can be well described by an "adsorption window"; (3) the "adsorption window" can be broadened by exploiting the bridge role of Ca(2+) ions; and (4) by introducing a cationic lipid into the zwitterionic lipid bilayer, one can achieve preferential adsorption of anionic QDs but suppression of the cationic QD adsorption. Our QCM-D data also indicates that these different adsorption traits effect different changes in the dissipation of supported lipid bilayers (SLBs) after adsorption of the charged QDs. The different adsorption propensities of cationic and anionic QDs on SLBs have reinforced the picture of electrostatic interactions. We believe that these findings provide important information on QD-lipid membrane interactions, which will help to develop new drug molecules and efficient drug delivery systems, and to predict and unravel their potential toxicities if any.

Chemical Basis of Interactions Between Engineered Nanoparticles and Biological Systems

“…A quartz crystal microbalance (QCM) with dissipation monitoring can be used for real-time monitoring of nanoparticle-lipid membrane interactions. 74 Fluorescence microscopy, 65,75 fluorescence spectroscopy, 68 fluorescence correlation spectroscopy (FCS), 73 Föster resonance energy transfer, 73,76 NMR 77 and liposomal leakage assay 78 have all been used to study the biophysical changes and disruptions of model lipid membranes or liposomes by nanoparticles.…”

Supported lipid bilayers with encapsulated quantum dots (QDs) via liposome fusion: effect of QD size on bilayer formation and structure

“…A number of QDs such as CdSe, 21 CdSe/ZnS, 22,23 CdSe/CdZnS, 16 CdTe, 17,24 and carbon 25 have been embedded into the hydrophobic tail region of liposomes without significantly compromising the liposome structure. Nonspecific QD adsorption to pre-formed supported lipid bilayers (SLBs) 26 and polyelectrolyte multilayers (PEMs) 27 has also been previously studied. However, the formation and structure of QD-embedded SLBs via the fusion of QD-endowed liposomes has not been reported, which is the focus of the current study.…”

Studies on intracellular delivery of carboxyl-coated CdTe quantum dots mediated by fusogenic liposomes

“…This hypothesis is supported by the work described by Zhang et al, where the authors demonstrated that adsorption between charged QDs and zwitterionic membranes can be favored by charges, which in turn can be controlled by the environmental pH and by the membrane and QD compositions. 47 The authors have shown the existence of an "adsorption window" that can govern the binding (or not) of QDs to lipids when these species display opposite charges. In this way, interactions between the negative carboxyl-coated QDs and cationic membranes (liposomes or cells) may well explain the co-localized pattern observed in Fig.…”