Isolating Nanoparticles from Complex Biological Media by Immunoprecipitation

Abstract

Polyethylene glycol (PEG) is considered the gold standard to prepare long circulating nanoparticles. The hydrophilic layer that sterically protects PEGylated nanomedicines also impedes their separation from biological media. In this study, we describe an immunoprecipitation method using AntiPEG antibodies cross-linked to magnetic beads to extract three types of radiolabeled PEGylated systems: polymeric nanoparticles, liposomes, and therapeutic proteins. The potential of the method is emphasized by isolating these systems after in vivo administration and ex vivo incubation in human biological fluids. Immunoprecipitation also allows a unique perspective on the size distribution of nanoparticles in the bloodstream after intravenous and intraperitoneal administrations. Further, we highlight the potential of the approach to inform on nanomaterial-associated drug in plasma as well as help characterize the protein corona. Altogether, we believe this method answers an unmet need in nanomedicine research and will contribute a fresh perspective on the interactions of nanomedicines with biological systems.

Comment on “Optimal centrifugal isolating of liposome–protein complexes from human plasma” by L. Digiacomo, F. Giulimondi, A. L. Capriotti, S. Piovesana, C. M. Montone, R. Z. Chiozzi, A. Laganá, M. Mahmoudi, D. Pozzi and G. Caracciolo,Nanoscale Adv., 2021,3, 3824

“…5 Specic immunoprecipitation methods for isolating liposomes and their protein corona have recently been demonstrated. 6,7 While these methods are indeed very neat and specic, they may not capture the entire liposome population, and are typically limited to PEGylated liposomes rather than being generic. Pattipeiluhu et al presented an elegant method relying on click chemistry, but even though it can be carried out with nonPEGylated nanocarriers, it still relies on specic labels.…”

“…3 To overcome these hurdles, the methodologies used to study the protein corona are becoming still more sophisticated. [6][7][8][9] A non-fullled goal is to establish efficient and well-aligned protocols for nanocarrier isolation, including proper controls, which make it possible to obtain high yield and purities of the nanocarrier isolate and to compare studies across laboratories. 2,10,11 As part of this activity, researchers are beginning to compare the different available methodologies, to determine which is the optimal method for investigating the protein corona of various types of nanoparticles.…”

“…2,10,11 As part of this activity, researchers are beginning to compare the different available methodologies, to determine which is the optimal method for investigating the protein corona of various types of nanoparticles. 4,6,7 In the recent paper, 12 Optimal centrifugal isolating of liposome-protein complexes from human plasma, Digiacomo et al state that "it is clear that centrifugation should be the technique of choice for studies on the liposome-protein corona". Here, we challenge this statement by presenting ndings from the bulk literature and providing new experimental data.…”

“…2,10,11 As part of this activity, researchers are beginning to compare the different available methodologies, to determine which is the optimal method for investigating the protein corona of various types of nanoparticles. 4,6,7…”

Kidney functional stages influence the role of PEG end-group on the renal accumulation and distribution of PEGylated nanoparticles

“…5,6 The basic properties of PEG on the nanoparticle (NP) surface have been shown to be important in protecting NPs from clearance during circulation. 7,8 In addition to the molecular weight, 9 density, 7,10 and conformation, 10 PEG end-groups may also have important influences on how PEG shells on NPs interact with serum and cell-surface proteins. 11,12 However, the effects of PEG end-groups on the in vivo fate of PEGylated NPs are still unclear.…”