Plasma protein adsorption patterns on liposomes: Establishment of analytical procedure

Abstract

After intravenous (i.v.) injection, colloidal drug carriers such as liposomes, emulsions, polymeric or solid lipid nanoparticles immediately interact with plasma proteins. The adsorbed plasma protein patterns depend on physico-chemical characteristics of the carriers' surface and are regarded as a key factor for the in vivo behavior of the carriers. The comprehension of the correlation between protein adsorption and in vivo organ distribution can be utilized to obtain drug targeting to different tissues. Carriers with different protein adsorption patterns will interact with different tissue-specific receptors or will be recognized by different macrophage subpopulations. Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) was applied to determine the protein adsorption patterns on polystyrene particles as model carriers. To transfer this analytical method to i.v. injectable colloidal carriers such as liposomes, a new sample preparation method was developed. The separation of liposomes from plasma after incubation was achieved by gel filtration using a Sepharose 2B column. This technique allowed a mild separation independent from eluent composition and only according to size differences. Possible protein desorption from the liposomes and adsorption onto the gel were minimized by using an eluent with a sufficiently high ionic strength. To estimate the efficiency of separation, the content of liposomes and plasma in each fraction being eluted was determined by ultraviolet (UV) spectroscopy. With this new separation method plasma protein adsorption patterns on liposomes could be analyzed for the first time. The sample preparation by gel filtration seemed to have no influence on liposome stability as far as size distribution is concerned.

Protein corona: a new approach for nanomedicine design

“…26 After separation of protein-NP complexes from incubation media or, isolation of protein from NP with further steps, electrophoresis was often applied for identification and qualitative determination of protein corona composition. 19,24,25,27 In addition, gel filtration can be used to not only separate protein-NP complexes from incubation media, 28,29 but also to isolate protein from NP surfaces as well as provide information of kinetic exchange rate for adsorbed proteins. 30 A positive point about gel filtration is that it can both separate and isolate adsorbed proteins from easily deformed and low-density NPs such as liposomes and exosomes.…”

Understanding the nanoparticle–protein corona using methods to quantify exchange rates and affinities of proteins for nanoparticles

“…A central methodological problem is to separate free protein from protein bound to nanoparticles, ideally employing nonperturbing methods that do not disrupt the protein-particle complex or induce additional protein binding. The preferred method to-date has been centrifugation, identifying the major serum proteins albumin, IgG and fibrinogen as being associated with a wide range of particles of seemingly disparate molecular composition (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). Due to its high abundance, albumin is almost always observed on particles and may be retrieved even if it has relatively low affinity.…”

The Impact of Nanoparticle Protein Corona on Cytotoxicity, Immunotoxicity and Target Drug Delivery

“…The presence of other biomolecules such as sugars, nucleic acids and lipids is expected but so far little studied [4,5]. The first studies on the interactions between NPs and plasma proteins were conducted between 1996 and 2000 [6][7][8], but it was the group of Dawson that first introduced the NP-PC complex concept [3]. The synthetic identity of the NP was replaced by a new biological identity, namely, the NP-PC complex (Figure 1) and as a consequence, researchers are now starting to consider NP-PC complexes as the new NPs.…”