Light-triggered release from dye-loaded fluorescent lipid nanocarriers in vitro and in vivo

Abstract

Light is an attractive trigger for release of active molecules from nanocarriers in biological systems. Here, we describe a phenomenon of light-induced release of a fluorescent dye from lipid nano-droplets under visible light conditions. Using auto-emulsification process we prepared nanoemulsion droplets of 32nm size encapsulating the hydrophobic analogue of Nile Red, NR668. While these nano-droplets cannot spontaneously enter the cells on the time scale of hours, after illumination for 30s under the microscope at the wavelength of NR668 absorption (535nm), the dye showed fast accumulation inside the cells. The same phenomenon was observed in zebrafish, where nano-droplets initially staining the blood circulation were released into endothelial cells and tissues after illumination. Fluorescence correlation spectroscopy revealed that laser illumination at relatively low power (60mW/cm) could trigger the release of the dye into recipient media, such as 10% serum or blank lipid nanocarriers. The photo-release can be inhibited by deoxygenation with sodium sulfite, suggesting that at least in part the release could be related to a photochemical process involving oxygen, though a photo-thermal effect could also take place. Finally, we showed that illumination of NR668 can provoke the release into the cells of another highly hydrophobic dye co-encapsulated into the lipid nanocarriers. These results suggest dye-loaded lipid nano-droplets as a prospective platform for preparation of light-triggered nanocarriers of active molecules.

BODIPY-loaded polymer nanoparticles: chemical structure of cargo defines leakage from nanocarrier in living cells

“…The leakage of dyes was evaluated by fluorescence correlation spectroscopy (FCS) ( Table 1). [64][65][66] FCS is a powerful tool to characterize NPs size 67 and polydipersity, 68 as well as to evaluate their behavior in biological media, 69 including their stability, 70,71 and formation of protein corona on the surface of NPs. 72,73 Recent studies showed the possibility to use FCS to study leakage of dyes from unilamellar lipid vesicles, 74 and lipid nano-droplets directly in biological media.…”

Optimizing the Fluorescence Properties of Nanoemulsions for Single Particle Tracking in Live Cells

“…Although DBS dyes were shown to have reduced brightness in non-viscous environments, in bioimaging experiments such dye leakage phenomenon can lead to decreasing of NEs brightness itself and thus enhancing the background noise. 21,59 In order to estimate the dye leakage, Fluorescent Correlation Spectroscopy (FCS) measurements were conducted in PBS alone and in the presence of 10 %(v/v) fetal bovine serum (FBS) ( Table 3). Serum is an appropriate model of biological dye acceptor as it contains a high variety of amphiphilic biomolecules especially lipoproteins.…”

Quantifying Release from Lipid Nanocarriers by Fluorescence Correlation Spectroscopy

“… 30 , 31 FCS serves as a tool for measuring the size 32 and polydispersity 33 of nanoparticles, as well as for evaluating their behavior in complex biological media 34 and their stability. 35 , 36 Also in many reports, FCS has been used to characterize the formation of the protein corona on the surface of nanoparticles 37 − 39 or the interaction of human serum albumin with liposomes. 40 However, only few studies have reported the use of FCS to study the release of cargo from nanoparticles.…”