Pressure-Controlled Encapsulation of Graphene Quantum Dots into Liposomes by the Reverse-Phase Evaporation Method

Abstract

Ultrasmall nanoparticles (USNPs) with sizes below 10 nm have shown great potentials in medical applications owing to their outstanding physical, chemical, optical, and biological properties. However, they suffer from a rapid renal clearance and biodegradation rate in the biological environment due to the small size. Liposomes are one of the most promising delivery nanocarriers for loading USNPs because of their excellent biocompatibility and lipid bilayer structure. Encapsulation of USNPs into liposomes in an efficient and controllable manner remains a challenge. In this study, we achieved a high loading of graphene quantum dots (GQDs, ∼4 nm), a typical USNP, into the aqueous core of liposomes (45.68 ± 1.44%), which was controllable by the pressure. The GQDs-loaded liposomes (GQDs-LPs) exhibited a very good aqueous stability for over a month. Furthermore, indocyanine green (ICG), an efficient near-infrared (NIR) photothermal agent, was introduced in the GQDs-LP system that could convert NIR laser energy into thermal energy and break down the liposomes, causing the release of GQDs in 6 min. Moreover, this NIR light-controlled release system (GQDs-ICG-LPs) also exhibited a good photothermal therapeutic performance in vitro, and 75% of cancer cells were killed at a concentration of 200 μg/mL. Overall, the successful development of the NIR light-controlled release system has laid a solid foundation for the future biomedical application of USNPs-loaded liposomes.

Methods of Liposomes Preparation: Formation and Control Factors of Versatile Nanocarriers for Biomedical and Nanomedicine Application

“…The constructed MCLs (of <200 nm) offer a magnetic resonance imaging contrast enhancement agent (due to the encapsulated magnetic nanoparticles), and can be considered a promising nanovector for image-guided gene-delivery therapy. Recently, a (pressure-controlled) encapsulation of graphene quantum dots (GQDs) into liposome nanocarriers has been obtained by the reverse-phase evaporation method [ 93 ]. The GQDs-loaded liposomes exhibited a high loading of ultra-small (~4 nm) GQDs into the aqueous liposomes’ cores (45.68 ± 1.44%), which was controllable by the pressure, and exhibited a very good stability for over a month.…”

“…Furthermore, the inclusion of the indocyanine green (an near-infrared photothermal agent) could convert NIR laser energy into thermal energy and break down the liposomes, causing the release of GQDs in 6 min. This NIR light-controlled drug-release nanoformulation exhibited a good in vitro (photothermal) therapeutic performance, and 75% of cancer cells were killed at a concentration of 200 μg/mL [ 93 ]. The successful development of these controlled-release nanocarriers by the reverse-phase evaporation method may stimulate future biomedical applications of advanced liposome theranostic systems.…”

A state-of-the-art liposome technology for glioblastoma treatment

“…6III). 47,53 The main advantage of this technique is its simple process, suitable EE, and easy synthesis. However, its main drawbacks are the need for a large quantity of organic solvent, the production of both MLVs and LUVs, it is not suitable for fragile bioactive drugs, time-consuming process, and the need for sterilization.…”

“…However, its main drawbacks are the need for a large quantity of organic solvent, the production of both MLVs and LUVs, it is not suitable for fragile bioactive drugs, time-consuming process, and the need for sterilization. 47,48 Freeze-drying (FD) employs low temperature and low pressure for the preparation of nanoformulations, mainly involving the removal of frozen water from liposomes. A reconstructed liposomal suspension is obtained after dispersing lyophilized liposomes in an aqueous medium (Fig.…”

Polyethylenimine-functionalized graphene quantum dots for Cd2+ ion adsorption

“…The GQDs were synthesized as previously reported. 39 Briefly, carbon fiber (4.0 g) was added into a 250 mL round-bottomed flask, the concentrated sulfuric acid (135 mL) and nitric acid (45 mL) were further added into the same flask, and then continuously mixed up to obtain a homogeneous solution. The resulting mixture was sonicated at 30 1C for 1 h and then heated at 85 1C for 24 h. After cooling down the temperature of mixture at room temperature, the solution was diluted with 300 mL of deionized water, and the resulting suspension was centrifuged twice at 8000 rpm min À1 for 30 min.…”