The protein corona of circulating PEGylated liposomes

Abstract

Following systemic administration, liposomes are covered by a 'corona' of proteins, and preserving the surface functionality is challenging. Coating the liposome surface with polyethylene glycol (PEG) is the most widely used anti-opsonization strategy, but it cannot fully preclude protein adsorption. To date, protein binding has been studied following in vitro incubation to predict the fate of liposomes in vivo, while dynamic incubation mimicking in vivo conditions remains largely unexplored. The main aim of this investigation was to determine whether shear stress, produced by physiologically relevant dynamic flow, could influence the liposome-protein corona. The corona of circulating PEGylated liposome was thoroughly compared with that formed by incubation in vitro. Systematic comparison in terms of size, surface charge and quantitative composition was made by dynamic light scattering, microelectrophoresis and nano-liquid chromatography tandem mass spectrometry (nanoLC-MS/MS). Size of coronas formed under static vs. dynamic incubation did not appreciably differ from each other. On the other side, the corona of circulating liposomes was more negatively charged than its static counterpart. Of note, the variety of protein species in the corona formed in a dynamic flow was significantly wider. Collectively, these results demonstrated that the corona of circulating PEGylated liposomes can be considerably different from that formed in a static fluid. This seems to be a key factor to predict the biological activity of a liposomal formulation in a physiological environment.

Dispersion of Nanoparticles in Different Media Importantly Determines the Composition of Their Protein Corona

“…Composition of the NPs corona depends on the source of proteins [29–31], time [9,32] and temperature [33] of the incubation of NPs in biological fluids. Not all variables are so intuitive; corona composition can also be affected by serum heat inactivation [34], choice of anticoagulant [30], static versus dynamic conditions of the media [35] and even the presence of magnetic field in the case of iron oxide NPs [36]. Although many factors that define NPs protein corona composition are already well studied, there is one that has been addressed insufficiently—the composition of media used for dispersion of NPs.…”

Protein corona: a new approach for nanomedicine design

“…18 Centrifugation is the typical method to collect NP-protein complex from the interaction media and loosely adsorbed proteins, and sucrose cushion centrifugation allows the separation of complex in a short time (30 sec). 11,12,22,23 The secondary structure of proteins can be evaluated by circular dichroism. However, this method cannot be used for a mixture of proteins due to its spectral complexity.…”

“…Therefore, it is essential to evaluate protein-NP interactions in a biomimetic environment which mimics in vivo physiological conditions to more accurately predict the fate of NPs in vivo. 22 …”

PEGylated and Functionalized Aliphatic Polycarbonate Polyplex Nanoparticles for Intravenous Administration of HDAC5 siRNA in Cancer Therapy

“…Indeed, the high amount of anionic serum proteins can interact and cover the surface of cationic nanovectors, forming a "protein corona" around the particle. 36 The formation of this corona changes the identity of the nanovectors. First, the negatively charged proteins can compete with the siRNA on the binding to the nanovectors, resulting in a premature release of the siRNA in the bloodstream.…”