Do plasma proteins distinguish between liposomes of varying charge density?

Absence of Anaphylactic Reactions to Injection of Hemoglobin Vesicles (Artificial Red Cells) to Rodents

The safety and efficacy of hemoglobin vesicles (HbVs) as artificial oxygen carriers encapsulating a purified and concentrated Hb solution in liposomes have been studied extensively. The HbV surface, modified with PEG by incorporating a PEG-conjugated phospholipid, is beneficial for storage and biocompatibility. However, it might be possible that interaction of PEG and the pre-existing anti-PEG antibody in the bloodstream causes acute adverse reaction. This study used two sets of experiments with rats and guinea pigs to ascertain whether the anti-PEG antibody generated by the PEG-modified HbV injection can induce anaphylactic reactions. SD rats received repeated intravenous injection of HbV at a dose rate of 16 or 32 mL/kg three times. Not anti-PEG IgG but anti-PEG IgM was detected. Nevertheless, no anaphylactic reaction occurred. Guinea pigs were used to study the presence of active systemic anaphylaxis further after injections of the PEG-modified liposomes used for HbV. The animals were sensitized by three repeated subcutaneous injections of PEG-modified liposomes (PEG-liposome) along with adjuvant at 1 week intervals. For comparison, unmodified liposomes (liposome) and 10 times excessively PEG-modified liposomes with ionizable lipid (10PEG-DODAP-liposome) were used. Inclusion of PEG modification induced not only anti-PEG IgM but also anti-PEG IgG. Three weeks after the final injection, intravenous injection of both PEG-liposome and liposome (1 mL/kg) induced no anaphylactic reaction. However, the injection of 10PEG-DODAP-liposome showed one lethal anaphylaxis case and one mild anaphylaxis case. Antisera obtained from the animal sensitized as described above were inoculated (0.05 mL) intradermally into fresh guinea pigs. The presence of passive cutaneous anaphylaxis was evaluated after intravenous injections (1 mL/kg) of three liposomes with Evans blue. No dye leakage was detected at any inoculated skin point for PEG-liposome or liposome, but a slight leakage was detected in one inoculated skin point for 10PEG-DODAP-liposome. These results indicate the absence of acute allergic reactions at repeated injections of HbVs despite the anti-PEG antibody induction. Not all the PEG-modified liposomes show anaphylaxis, and it may depend on the amount of PEGylated phospholipid and lipid composition of PEG-modified liposomes.

Systematic modulation of the lipid composition enables the tuning of liposome cellular uptake

As liposomes have been widely explored as drug delivery carriers over the past decades, they are one of the most promising platforms due to their biocompatibility and versatility for surface functionalization. However, to improve the specific design of liposomes for future biomedical applications such as nanovaccines, it is necessary to understand how these systems interact with cell membranes, as most of their potential applications require them to be internalized by cells. Even though several investigations on the cellular uptake of liposomes were conducted, the effect of the liposome membrane properties on internalization in different cell lines remains unclear. Here, we demonstrate how the cellular uptake behavior of liposomes can be driven towards preferential interaction with dendritic cells (DC2.4) as compared to macrophages (RAW264.7) by tuning the lipid composition with varied molar ratios of the lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE). Cellular internalization efficiency was analyzed by flow cytometry, as well as liposome-cell membrane co-localization by confocal laser scanning microscopy. The corresponding proteomic analysis of the protein corona was performed in order to unravel the possible effect on the internalization. The obtained results of this work reveal that it is possible to modulate the cellular uptake towards enhanced internalization by dendritic cells just by modifying the applied lipids and, thus, mainly the physico-chemical properties of the liposomes. STATEMENT OF SIGNIFICANCE: In the field of nanomedicine, it is of key importance to develop new specific and efficient drug carriers. In this sense, liposomes are one of the most widely known carrier types and used in clinics with good results. However, the exact interaction mechanisms of liposomes with cells remain unclear, which is of great importance for the design of new drug delivery platforms. Therefore, in this work we demonstrate that cellular uptake depends on the lipid composition. We are able to enhance the uptake in a specific cell type just by tuning the content of a lipid in the liposome membrane. This finding could be a step towards the selective design of liposomes to be internalized by specific cells with promising applications in biomedicine.

Protein-liposome interactions: the impact of surface charge and fluidisation effect on protein binding

At the dawn of a new nanotechnological era in the pharmaceutical field, it is very important to examine and understand all the aspects that influence in vivo behaviour of nanoparticles. In this point of view, the interactions between serum proteins and liposomes with incorporated anionic, cationic, and/or PEGylated lipids were investigated to elucidate the role of surface charge and bilayer fluidity in protein corona's formation. 1,2-dipalmitoyl-sn-glycero-3- phosphocholine (DPPC), hydrogenated soybean phosphatidylcholine (HSPC), and 1,2-dioctadecanoyl-sn-glycero-3-phosphocholine (DSPC) liposomes with the presence or absence of 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (sodium salt) (DPPG), 1,2-di-(9Z-octadecenoyl)-3-trimethylammonium-propane (chloride salt) (DOTAP), and/or 1,2-dipalmitoylsn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-5000] (DPPE-PEG 5000) lipids were prepared by the thin-film hydration method. The evaluation of their biophysical characteristics was enabled by differential scanning calorimetry and dynamic and electrophoretic light scattering. The physicochemical characteristics of mixed liposomes were compared before and after exposure to foetal bovine serum (FBS) and were correlated to calorimetric data. Our results indicate protein binding to all liposomal formulations. However, it is highlighted the importance of surface charge and fluidisation effect to the extent of protein adsorption. Additionally, considering the extensive use of cationic lipids for innovative delivery platforms, we deem PEGylation a key parameter, because even in a small proportion can reduce protein binding, and thus fast clearance and extreme toxicity without affecting positive charge. This study is a continuation of our previous work about protein-liposome interactions and fraction of stealthiness (Fs) parameter, and hopefully a design road map for drug and gene delivery.

Liposome-Polymer Complex for Drug Delivery System and Vaccine Stabilization

Liposomes have been used extensively as micro- and nanocarriers for hydrophobic or hydrophilic molecules. However, conventional liposomes are biodegradable and quickly eliminated, making it difficult to be used for delivery in specific routes, such as the oral and systemic routes. One way to overcome this problem is through complexation with polymers, which is referred to as a liposome complex. The use of polymers can increase the stability of liposome with regard to pH, chemicals, enzymes, and the immune system. In some cases, specific polymers can condition the properties of liposomes to be explicitly used in drug delivery, such as targeted delivery and controlled release. These properties are influenced by the type of polymer, crosslinker, interaction, and bond in the complexation process. Therefore, it is crucial to study and review these parameters for the development of more optimal forms and properties of the liposome complex. This article discusses the use of natural and synthetic polymers, ways of interaction between polymers and liposomes (on the surface, incorporation in lamellar chains, and within liposomes), types of bonds, evaluation standards, and their effects on the stability and pharmacokinetic profile of the liposome complex, drugs, and vaccines. This article concludes that both natural and synthetic polymers can be used in modifying the structure and physicochemical properties of liposomes to specify their use in targeted delivery, controlled release, and stabilizing drugs and vaccines.

The impact of protein corona on the biological behavior of targeting nanomedicines

For successful translation of targeting nanomedicines from bench to bedside, it is vital to address their most common drawbacks namely rapid clearance and off-target accumulation. These complications evidently originate from a phenomenon called "protein corona (PC) formation" around the surface of targeting nanoparticles (NPs) which happens once they encounter the bloodstream and interact with plasma proteins with high collision frequency. This phenomenon endows the targeting nanomedicines with a different biological behavior followed by an unexpected fate, which is usually very different from what we commonly observe in vitro. In addition to the inherent physiochemical properties of NPs, the targeting ligands could also remarkably dictate the amount and type of adsorbed PC. As very limited studies have focused their attention on this particular factor, the present review is tasked to discuss the best simulated environment and latest characterization techniques applied to PC analysis. The effect of PC on the biological behavior of targeting NPs engineered with different targeting moieties is further discussed. Ultimately, the recent progresses in manipulation of nano-bio interfaces to achieve the most favorite therapeutic outcome are highlighted.

Spotlight on the protein corona of liposomes

Although an established drug delivery platform, liposomes have not fulfilled their true potential. In the body, interactions of liposomes are mediated by the layer of plasma proteins adsorbed on the surface, the protein corona. The review aims to collect the data of the last decade on liposome protein corona, tracing the path from interactions of individual proteins to the effects mediated by the protein corona in vivo. It offers a classification of the approaches to exploitation of the protein corona-rather than elimination thereof-based on the bilayer composition-corona composition-molecular interactions-biological performance framework. The multitude of factors that affect each level of this relationship urge to the widest implementation of bioinformatics tools to predict the most effective liposome compositions relying on the data on protein corona. Supplementing the picture with new pieces of accurately reported experimental data will contribute to the accuracy and efficiency of the predictions. STATEMENT OF SIGNIFICANCE: The review focuses on liposomes as an established nanomedicine platform and analyzes the available data on how the protein corona formed on liposome surface in biological fluids affects performance of the liposomes. The review offers a rigorous account of existing literature and critical analysis of methodology currently applied to the assessment of liposome-plasma protein interactions. It introduces a classification of the approaches to exploitation of the protein corona and tailoring liposome carriers to advance the field of nanoparticulate drug delivery systems for the benefit of patients.

Isolation methods commonly used to study the liposomal protein corona suffer from contamination issues

The liposomal protein corona has been the focus of numerous studies, but there is still no consensus regarding its extent and composition. Rather, the literature is full of conflicting reports on the matter. To elucidate whether there could be a methodological explanation for this, we here scrutinize the efficiency of three commonly used liposome isolation methods at isolating stealth liposomes from human plasma. Firstly, we show that size-exclusion chromatography (SEC) in its standard form is prone to isolating unbound protein material together with the liposomes, but also that the method may be optimized to mitigate this issue. Secondly, we demonstrate that SEC in combination with membrane ultrafiltration is no better at removing the unbound protein material than SEC alone. Thirdly, we show that centrifugation is not able to pellet the liposomes. Overall, our results suggest that previous research on the liposomal protein corona may have suffered from significant methodological problems, in particular related to contaminant proteins interfering with the analysis of the protein corona. We believe that the data presented here may help guide future research around this challenge to reach a converging understanding about the properties of the protein corona on liposomes. STATEMENT OF SIGNIFICANCE: Upon administration into the circulatory system, liposomal drug carriers encounter an environment rich in proteins. These proteins may adsorb to the liposomes to form what is known as the protein corona, potentially governing the interactions of the liposomes with tissues and cells. However, despite decades of intense research efforts, there is currently no clear understanding about the extent and composition of the liposomal protein corona, making it impossible to assess its mechanistic importance. Here we report that the methods commonly used to isolate liposomes from blood plasma or serum to study the protein corona are susceptible to protein contamination. This may be the underlying technical reason for the current confusion about the characteristics of the liposomal protein corona.

Interplay between nanomedicine and protein corona

Nanomedicine is recognized as a promising agent for diverse biomedical applications; however, its safety and efficiency in clinical practice remains to be enhanced. A priority issue is the protein corona (PC), which imparts unique biological identities to prototype and determines the actual biological functions in biological fluids. Decades of work has already illuminated abundant considerations that influence the composition of the protein corona. Thereinto, the physical assets of nanomedicines (e.g., size and shape, surface properties, nanomaterials) and the biological environment collectively play fundamental roles in shaping the PC, including the types and quantities of plasma proteins. The properties of nanomedicines are dependent on certain factors. This review aims to explore the applications of nanomedicines by regulating their interplay with PC.

Tailoring Iron Oxide Nanoparticles for Efficient Cellular Internalization and Endosomal Escape

Iron oxide nanoparticles (IONs) have been widely explored for biomedical applications due to their high biocompatibility, surface-coating versatility, and superparamagnetic properties. Upon exposure to an external magnetic field, IONs can be precisely directed to a region of interest and serve as exceptional delivery vehicles and cellular markers. However, the design of nanocarriers that achieve an efficient endocytic uptake, escape lysosomal degradation, and perform precise intracellular functions is still a challenge for their application in translational medicine. This review highlights several aspects that mediate the activation of the endosomal pathways, as well as the different properties that govern endosomal escape and nuclear transfection of magnetic IONs. In particular, we review a variety of ION surface modification alternatives that have emerged for facilitating their endocytic uptake and their timely escape from endosomes, with special emphasis on how these can be manipulated for the rational design of cell-penetrating vehicles. Moreover, additional modifications for enhancing nuclear transfection are also included in the design of therapeutic vehicles that must overcome this barrier. Understanding these mechanisms opens new perspectives in the strategic development of vehicles for cell tracking, cell imaging and the targeted intracellular delivery of drugs and gene therapy sequences and vectors.

Impact of the protein corona on nanomaterial immune response and targeting ability

Over the last decade nanomaterials have had a major impact on human health for the early detection and treatment of many diseases. The future success of clinically translatable nanomaterials lies in the combination of several functionalities to realize a personalized medical experience for patients. To maintain promises, concerns arising from toxic potential and off-target accumulation of nanomaterials must be addressed first. Upon introduction to a complex biological system (e.g., following systemic administration), nanomaterials interact with all the encountered biomolecules and form the protein corona, a complex coating of plasma proteins that provides them with a totally new biological identity. As the protein corona controls the nanomaterial behavior in vivo, a precise knowledge of the relationship between biological identity and physiological response is needed but not yet achieved. Based on impressive progress made thus far, this review critically discusses how the protein corona activates immune response and influences the targeted delivery of nanomaterials. Furthermore, we comment on emerging strategies to manipulate protein binding in order to promote formation of designer artificial coronas and achieve a desired therapeutic outcome. We conclude by debating challenges that must be overcome to obtain widespread clinical adoption of nanomaterials. This article is categorized under: Nanotechnology Approaches to Biology > Cells at the Nanoscale Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Tuning liposome composition to modulate corona formation in human serum and cellular uptake

Nano-sized objects such as liposomes are modified by adsorption of biomolecules in biological fluids. The resulting corona critically changes nanoparticle behavior at cellular level. A better control of corona composition could allow to modulate uptake by cells. Within this context, in this work, liposomes of different charge were prepared by mixing negatively charged and zwitterionic lipids to different ratios. The series obtained was used as a model system with tailored surface properties to modulate corona composition and determine the effects on liposome interactions with cells. Uptake efficiency and uptake kinetics of the different liposomes were determined by flow cytometry and fluorescence imaging. Particular care was taken in optimizing the methods to isolate the corona forming in human serum to prevent liposome agglomeration and to exclude residual free proteins, which could confuse the results. Thanks to the optimized methods, mass spectrometry of replicate corona isolations showed excellent reproducibility and this allowed semi-quantitative analysis to determine for each formulation the most abundant proteins in the corona. The results showed that by changing the fraction of zwitterionic and charged lipids in the bilayer, the amount and identity of the most abundant proteins adsorbed from serum differed. Interestingly, the formulations also showed very different uptake kinetics. Similar approaches can be used to tune lipid composition in a systematic way in order to obtain formulations with the desired corona and cell uptake behavior. STATEMENT OF SIGNIFICANCE: Liposomes and other nano-sized objects when introduced in biological fluids are known to adsorb biomolecules forming the so-called nanoparticle corona. This layer strongly affects the subsequent interactions of liposomes with cells. Here, by tuning lipid composition in a systematic way, a series of liposomes with tailored surface properties has been prepared to modulate the corona forming in human serum. Liposomes with very different cellular uptake kinetics have been obtained and their corona was identified in order to determine the most enriched proteins on the different formulations. By combining corona composition and uptake kinetics candidate corona proteins associated with reduced or increased uptake by cells can be identified and the liposome formulation can be tuned to obtain the desired uptake behavior.

Effect of Protein Corona on The Transfection Efficiency of Lipid-Coated Graphene Oxide-Based Cell Transfection Reagents

Coating graphene oxide nanoflakes with cationic lipids leads to highly homogeneous nanoparticles (GOCL NPs) with optimised physicochemical properties for gene delivery applications. In view of in vivo applications, here we use dynamic light scattering, micro-electrophoresis and one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis to explore the bionano interactions between GOCL/DNA complexes (hereafter referred to as "grapholipoplexes") and human plasma. When exposed to increasing protein concentrations, grapholipoplexes get covered by a protein corona that evolves with protein concentration, leading to biocoronated complexes with modified physicochemical properties. Here, we show that the formation of a protein corona dramatically changes the interactions of grapholipoplexes with four cancer cell lines: two breast cancer cell lines (MDA-MB and MCF-7 cells), a malignant glioma cell line (U-87 MG) and an epithelial colorectal adenocarcinoma cell line (CACO-2). Luciferase assay clearly indicates a monotonous reduction of the transfection efficiency of biocoronated grapholipoplexes as a function of protein concentration. Finally, we report evidence that a protein corona formed at high protein concentrations (as those present in in vivo studies) promotes a higher capture of biocoronated grapholipoplexes within degradative intracellular compartments (e.g., lysosomes), with respect to their pristine counterparts. On the other hand, coronas formed at low protein concentrations (human plasma = 2.5%) lead to high transfection efficiency with no appreciable cytotoxicity. We conclude with a critical assessment of relevant perspectives for the development of novel biocoronated gene delivery systems.

A comprehensive analysis of liposomal biomolecular corona upon human plasma incubation: The evolution towards the lipid corona

When drug nanocarriers enter a physiological environment, their surface gets coated by a dynamic biomolecular corona (BMC) mainly constituted by proteins. Although a deep investigation has been performed on the composition of BMC in terms of proteins, scarce attention has been posed to low molecular weight metabolites present in human plasma. In this work, for the first time, the investigation of the BMC of liposomal nanoparticles (NPs) constituted by 1,2-dioleoyl-3-trimethylammonium-propane polar lipid has been carried out by an ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry based untargeted metabolomics approach. Compounds were tentatively identified based on matches with online databases and comparison of MS/MS spectra with available spectral libraries. Moreover, a comparison of three metabolite extraction strategies, including an ultrafiltration membrane based protocol, a methanol extraction based protocol, and Wessel & Flügge protocol, was performed. Methanol extraction procedure resulted in the widest metabolic coverage of liposomal NP BMC. A total of 193 metabolites has been tentatively identified, 166 of which belonged to the class of lipids including phospholipids, steroids, carnitines, fatty alcohols, diglycerides and fatty acids. The high abundance of lipids in the BMC can be explained by the adsorption of plasma lipoproteins onto liposome surface, confirming previous works on other kinds of NPs. Lipids are important bioactive molecules, which could impact NP circulation and uptake by cells. Extending the investigation of BMC beyond the protein corona and towards the "lipid corona" may be the keystone of a better understanding and control of NP fate in human body.

Brain Targeting by Liposome-Biomolecular Corona Boosts Anticancer Efficacy of Temozolomide in Glioblastoma Cells

Temozolomide (TMZ) is the current first-line chemotherapy for treatment of glioblastoma multiforme (GBM). However, similar to other brain therapeutic compounds, access of TMZ to brain tumors is impaired by the blood-brain barrier (BBB) leading to poor response for GBM patients. To overcome this major hurdle, we have synthesized a set of TMZ-encapsulating nanomedicines made of four cationic liposome (CL) formulations with systematic changes in lipid composition and physical-chemical properties. The targeting nature of this nanomedicine is provided by the recruitment of proteins, with natural targeting capacity, in the biomolecular corona (BC) layer that forms around CLs after exposure to human plasma (HP). TMZ-loaded CL-BC complexes were thoroughly characterized by dynamic light scattering (DLS), electrophoretic light scattering (ELS), and nanoliquid chromatography tandem mass spectrometry (nano-LC MS/MS). BCs were found to be enriched of typical BC fingerprints (BCFs) (e.g., Apolipoproteins, Vitronectin, and vitamin K-dependent protein), which have a substantial capacity in binding to receptors that are overexpressed at the BBB (e.g., scavenger receptor class B, type I and low-density lipoprotein receptor). We found that the CL formulation exhibiting the highest levels of targeting BCFs had larger uptake in human umbilical vein endothelial cells (HUVECs) that are commonly used as an in vitro model of the BBB. This formulation could also deliver TMZ to the human glioblastoma U-87 MG cell line and thus substantially enhance their antitumor efficacy compared to corona free CLs. Thus, we propose that the BC-based nanomedicines may pave a more effective way for efficient treatment of GBM.

Cubic lyotropic liquid crystals as drug delivery carriers: Physicochemical and morphological studies

The self-assembly process of amphiphilic molecules into solvents results in different mesophases, such as inverse cubic and hexagonal that both belong to the wider category of lyotropic liquid crystals. The above mesophases can be further exploited upon the formation of liquid crystalline nanoparticles, cubosomes and hexosomes respectively, which may be utilized as drug delivery nanosystems, exhibiting major advantages. In the present study, liquid crystalline nanoparticles were prepared and evaluated in terms of morphology and physicochemical behavior. The goal of this study is to examine the effect of the different formulation parameters, as well as the effect of the different microenvironmental factors (temperature, ionic strength, pH, serum proteins presence) on their behavior. The physicochemical behavior and the morphology of the systems were investigated by X-Ray Diffraction (XRD), cryogenic-Transmission Electron Microscopy (cryo-TEM), fluorescence spectroscopy and a gamut of light scattering techniques. The formulation process was proved to influence strictly the physicochemical behavior of the prepared nanosystems. They presented colloidal stability over time and upon ionic strength increase, but they were affected by the presence of proteins and presented reversible structure alterations upon temperature increase. Their morphological structure and internal microenvironment, reflected by micropolarity and microfluidity, were also influenced by the formulation parameters.

Cytotoxicity of CeO2 nanoparticles using in vitro assay with Mytilus galloprovincialis hemocytes: Relevance of zeta potential, shape and biocorona formation

Over the last decades, the growth in nanotechnology has provoked an increase in the number of its applications and consumer products that incorporate nanomaterials in their formulation. Metal nanoparticles are released to the marine environment and they can interact with cells by colloids forces establish a nano-bio interface. This interface can be compatible or generate bioadverse effects to cells. The daily use of CeO₂ nanoparticles (CeO₂ NPs) in industrial catalysis, sunscreen, fuel cells, fuel additives and biomedicine and their potential release into aquatic environments has turned them into a new emerging pollutant of concern. It is necessary to assess of effects of CeO₂ NPs in aquatic organisms and understand the potential mechanisms of action of CeO₂ NP toxicity to improve our knowledge about the intrinsic and extrinsic characteristic of CeO₂ NPs and the interaction of CeO₂ NPs with biomolecules in different environment and biological fluids. The conserved innate immune system of bivalves represents a useful tool for studying immunoregulatory responses when cells are exposed to NPs. In this context, the effects of two different CeO₂ NPs with different physico-chemical characteristics (size, shape, zeta potential and Ce⁺³/Ce⁺⁴ ratio) and different behavior with biomolecules in plasma fluid were studied in a series of in vitro assays using primary hemocytes from Mytilus galloprovincialis. Different cellular responses such as lysosome membrane stability, phagocytosis capacity and extracellular reactive oxygen species (ROS) production were evaluated. Our results indicate that the agglomeration state of CeO₂ NPs in the exposure media did not appear to have a substantial role in particle effects, while differences in shape, zeta potential and biocorona formation in NPs appear to be important in provoking negative impacts on hemocytes. The negative charge and the rounded shape of CeO₂ NPs, which formed Cu, Zn-SOD biocorona in hemolymph serum (HS), triggered higher changes in the biomarker of stress (LMS) and immunological parameters (ROS and phagocytosis capacity). On the other hand, the almost neutral surface charge and well-faceted shape of CeO₂ NPs did not show either biocorona formation in HS under tested conditions or significant responses. According to the results, the most relevant conclusion of this work is that not only the physicochemical characterization of CeO₂ NPs plays an important role in NPs toxicity but also the study of the interaction of NPs with biological fluids is essential to know it behavior and toxicity at cellular level.

Development and evaluation of injectable nanosized drug delivery systems for apigenin

The purpose of this study was to develop different injectable nanosized drug delivery systems (NDDSs) i.e. liposome, lipid nanocapsule (LNC) and polymeric nanocapsule (PNC) encapsulating apigenin (AG) and compare their characteristics to identify the nanovector(s) that can deliver the largest quantity of AG while being biocompatible. Two liposomes with different surface characteristics (cationic and anionic), a LNC and a PNC were prepared. A novel tocopherol modified poly(ethylene glycol)-b-polyphosphate block-copolymer was used for the first time for the PNC preparation. The NDDSs were compared by their physicochemical characteristics, AG release, storage stability, stability in serum, complement consumption and toxicity against a human macrovascular endothelial cell line (EAhy926). The diameter and surface charge of the NDDSs were comparable with previously reported injectable nanocarriers. The NDDSs showed good encapsulation efficiency and drug loading. Moreover, the NDDSs were stable during storage and in fetal bovine serum for extended periods, showed low complement consumption and were non-toxic to EAhy926 cells up to high concentrations. Therefore, they can be considered as potential injectable nanocarriers of AG. Due to less pronounced burst effect and extended release characteristics, the nanocapsules could be favorable approaches for achieving prolonged pharmacological activity of AG using injectable NDDS.

Biophysics and protein corona analysis of Janus cyclodextrin-DNA nanocomplexes. Efficient cellular transfection on cancer cells

The self-assembling processes underlining the capabilities of facially differentiated ("Janus") polycationic amphiphilic cyclodextrins (paCDs) as non-viral gene nanocarriers have been investigated by a pluridisciplinary approach. Three representative Janus paCDs bearing a common tetradecahexanoyl multitail domain at the secondary face and differing in the topology of the cluster of amino groups at the primary side were selected for this study. All of them compact pEGFP-C3 plasmid DNA and promote transfection in HeLa and MCF-7 cells, both in absence and in presence of human serum. The electrochemical and structural characteristics of the paCD-pDNA complexes (CDplexes) have been studied by using zeta potential, DLS, SAXS, and cryo-TEM. paCDs and pDNA, when assembled in CDplexes, render effective charges that are lower than the nominal ones. The CDplexes show a self-assembling pattern corresponding to multilamellar lyotropic liquid crystal phases, characterized by a lamellar stacking of bilayers of the CD-based vectors with anionic pDNA sandwiched among them. When exposed to human serum, either in the absence or in the presence of pDNA, the surface of the cationic CD-based vector becomes coated by a protein corona (PC) whose composition has been analyzed by nanoLC-MS/MS. Some of the CDplexes herein studied showed moderate-to-high transfection levels in HeLa and MCF-7 cancer cells combined with moderate-to-high cell viabilities, as determined by FACS and MTT reduction assays. The ensemble of data provides a detail picture of the paCD-pDNA-PC association processes and a rational base to exploit the protein corona for targeted gene delivery on future in vivo applications.

In vivo protein corona patterns of lipid nanoparticles

In vitro and in vivo biological identity of nanoparticles are substantially different.

Stirred, shaken, or stagnant: What goes on at the blood-biomaterial interface

There is a widely recognized need to improve the performance of vascular implants and external medical devices that come into contact with blood by reducing adverse reactions they cause, such as thrombosis and inflammation. These reactions lead to major adverse cardiovascular events such as heart attacks and strokes. Currently, they are managed therapeutically. This need remains unmet by the biomaterials research community. Recognized stagnation of the blood-biomaterial interface research translates into waning interest from clinicians, funding agencies, and practitioners of adjacent fields. The purpose of this contribution is to stir things up. It follows the 2014 BloodSurf meeting (74th International IUVSTA Workshop on Blood-Biomaterial Interactions), offers reflections on the situation in the field, and a three-pronged strategy integrating different perspectives on the biological mechanisms underlying blood-biomaterial interactions. The success of this strategy depends on reengaging clinicians and on the renewed cooperation of the funding agencies to support long-term efforts.

Nanoparticles-cell association predicted by protein corona fingerprints

In a physiological environment (e.g., blood and interstitial fluids) nanoparticles (NPs) will bind proteins shaping a "protein corona" layer. The long-lived protein layer tightly bound to the NP surface is referred to as the hard corona (HC) and encodes information that controls NP bioactivity (e.g. cellular association, cellular signaling pathways, biodistribution, and toxicity). Decrypting this complex code has become a priority to predict the NP biological outcomes. Here, we use a library of 16 lipid NPs of varying size (Ø≈ 100-250 nm) and surface chemistry (unmodified and PEGylated) to investigate the relationships between NP physicochemical properties (nanoparticle size, aggregation state and surface charge), protein corona fingerprints (PCFs), and NP-cell association. We found out that none of the NPs' physicochemical properties alone was exclusively able to account for association with human cervical cancer cell line (HeLa). For the entire library of NPs, a total of 436 distinct serum proteins were detected. We developed a predictive-validation modeling that provides a means of assessing the relative significance of the identified corona proteins. Interestingly, a minor fraction of the HC, which consists of only 8 PCFs were identified as main promoters of NP association with HeLa cells. Remarkably, identified PCFs have several receptors with high level of expression on the plasma membrane of HeLa cells.

The intracellular trafficking mechanism of Lipofectamine-based transfection reagents and its implication for gene delivery

Lipofectamine reagents are widely accepted as "gold-standard" for the safe delivery of exogenous DNA or RNA into cells. Despite this, a satisfactory mechanism-based explanation of their superior efficacy has remained mostly elusive thus far. Here we apply a straightforward combination of live cell imaging, single-particle tracking microscopy, and quantitative transfection-efficiency assays on live cells to unveil the intracellular trafficking mechanism of Lipofectamine/DNA complexes. We find that Lipofectamine, contrary to alternative formulations, is able to efficiently avoid active intracellular transport along microtubules, and the subsequent entrapment and degradation of the payload within acidic/digestive lysosomal compartments. This result is achieved by random Brownian motion of Lipofectamine-containing vesicles within the cytoplasm. We demonstrate here that Brownian diffusion is an efficient route for Lipofectamine/DNA complexes to avoid metabolic degradation, thus leading to optimal transfection. By contrast, active transport along microtubules results in DNA degradation and subsequent poor transfection. Intracellular trafficking, endosomal escape and lysosomal degradation appear therefore as highly interdependent phenomena, in such a way that they should be viewed as a single barrier on the route for efficient transfection. As a matter of fact, they should be evaluated in their entirety for the development of optimized non-viral gene delivery vectors.

A magnetic-dependent protein corona of tailor-made superparamagnetic iron oxides alters their biological behaviors

In recent years, it is becoming increasingly evident that once nanoparticles come into contact with biological fluids, a protein corona surely forms and critically affects the biological behaviors of nanoparticles. Herein, we investigate whether the formation of protein corona on the surface of superparamagnetic iron oxides (SPIOs) is influenced by static magnetic field. Under static magnetic field, there is no obvious variation in the total amount of protein adsorption, but the proportion of adsorbed proteins significantly changes. Noticeably, certain proteins including apolipoproteins, complement system proteins and acute phase proteins, increase in the protein corona of SPIOs in the magnetic field. More importantly, the magnetic-dependent protein corona of SPIOs enhances the cellular uptake of SPIOs into the normal cell line (3T3 cells) and tumor cell line (HepG2 cells), due to increased adsorption of apolipoprotein. In addition, SPIOs with the magnetic-dependent protein corona cause high cytotoxicity to 3T3 cells and HepG2 cells. This work discloses that superparamagnetism as a key feature of SPIOs affects the composition of protein corona to a large extent, which further alters the biological behaviors of SPIOs.

Exploring Cellular Interactions of Liposomes Using Protein Corona Fingerprints and Physicochemical Properties

To control liposomes fate and transport upon contact with biofluids, it is essential to consider several parameters affecting the synthetic and biological identity of liposomes, as well as liposome-protein corona (PC) aspects. As a powerful tool in this data mining adventure, quantitative structure-activity relationship (QSAR) approach is used to correlate physicochemical properties of liposomes and their PC fingerprints to multiple quantified biological responses. In the present study, the relationship between cellular interactions of a set of structurally diverse liposomal formulations and their physicochemical and PC properties has been investigated via linear and nonlinear QSAR models. Significant parameters affecting cellular uptake and cell viability of liposomes in two important cancer cell lines (PC3 and HeLa) have been identified. The developed QSARs have the capacity to be implemented in advanced targeted delivery of liposomal drugs.

The impact of nanoparticle protein corona on cytotoxicity, immunotoxicity and target drug delivery

In a perfect sequence of events, nanoparticles (NPs) are injected into the bloodstream where they circulate until they reach the target tissue. The ligand on the NP surface recognizes its specific receptor expressed on the target tissue and the drug is released in a controlled manner. However, once injected in a physiological environment, NPs interact with biological components and are surrounded by a protein corona (PC). This can trigger an immune response and affect NP toxicity and targeting capabilities. In this review, we provide a survey of recent findings on the NP-PC interactions and discuss how the PC can be used to modulate both cytotoxicity and the immune response as well as to improve the efficacy of targeted delivery of nanocarriers.

Stealth effect of biomolecular corona on nanoparticle uptake by immune cells

When injected in a biological milieu, a nanomaterial rapidly adsorbs biomolecules forming a biomolecular corona. The biomolecular corona changes the interfacial composition of a nanomaterial giving it a biological identity that determines the physiological response. Characterization of the biomolecular structure and composition has received increasing attention mostly due to its detrimental impact on the nanomaterial's metabolism in vivo. It is generally accepted that an opsonin-enriched biomolecular corona promotes immune system recognition and rapid clearance from circulation. Here we applied dynamic light scattering and nanoliquid chromatography tandem mass spectrometry to thoroughly characterize the biomolecular corona formed around lipid and silica nanoparticles (NPs). Incubation with human plasma resulted in the formation of NP-biomolecular coronas enriched with immunoglobulins, complement factors, and coagulation proteins that bind to surface receptors on immune cells and elicit phagocytosis. Conversely, we found that protein-coated NPs were protected from uptake by macrophage RAW 264.7 cells. This implies that the biomolecular corona formation provides a stealth effect on macrophage recognition. Our results suggest that correct prediction of the NP's fate in vivo will require more than just the knowledge of the biomolecular corona composition. Validation of efficient methods for mapping protein binding sites on the biomolecular corona of NPs is an urgent task for future research.

Serum protein adsorption and excretion pathways of metal nanoparticles

While the synthesis of metal nanoparticles (NPs) with fascinating optical and electronic properties have progressed dramatically and their potential biomedical applications were also well demonstrated in the past decade, translation of metal NPs into the clinical practice still remains a challenge due to their severe accumulation in the body. Herein, we give a brief review on size-dependent material properties of metal NPs and their potential biomedical applications, followed by a summary of how structural parameters such as size, shape and charge influence their interactions with serum protein adsorption, cellular uptake and excretion pathways. Finally, the future challenges in minimizing serum protein adsorption and expediting clinical translation of metal NPs were also discussed.

Surface chemistry and serum type both determine the nanoparticle-protein corona

The protein corona that forms around nanoparticles in vivo is a critical factor that affects their physiological response. The potential to manipulate nanoparticle characteristics such that either proteins advantageous for delivery are recruited and/or detrimental proteins are avoided offers exciting possibilities for improving drug delivery. In this work, we used nanoliquid chromatography tandem mass spectrometry to characterize the corona of five lipid formulations after incubation in mouse and human plasma with the hope of providing data that may contribute to a better understanding of the role played by both the nanoparticle properties and the physiological environment in recruiting specific proteins to the corona. Notably, we showed that minor changes in the lipid composition might critically affect the protein corona composition demonstrating that the surface chemistry and arrangement of lipid functional groups are key players that regulate the liposome-protein interactions. Notably, we provided evidence that the protein corona that forms around liposomes is strongly affected by the physiological environment, i.e., the serum type. These results are likely to suggest that the translation of novel pharmaceutical formulations from animal models to the clinic must be evaluated on a case-by-case basis.

BIOLOGICAL SIGNIFICANCE

In the present work nanoliquid chromatography tandem mass spectrometry was used to characterize the protein corona of five different liposome formulations after exposure to mouse and human plasma. The modern proteomic methods employed have clarified that the arrangement of lipid functional groups is a key player that regulates the liposome-protein interactions. We also clarified that the protein corona enrichment and complexity depend on the serum type. Our results suggest that the translational of novel pharmaceutical formulations from animal models to the clinic must be evaluated on a case-by-case basis.

Accessing to the minor proteome of red blood cells through the influence of the nanoparticle surface properties on the corona composition

Nanoparticle (NP)-protein interactions in complex samples have not yet been clearly understood. Nevertheless, several studies demonstrated that NP's physicochemical features significantly impact on the protein corona composition. Taking advantage of the NP potential to harvest different subsets of proteins, we assessed for the first time the capacity of three kinds of superparamagnetic NPs to highlight the erythrocyte minor proteome. Using both qualitative and quantitative proteomics approaches, nano-liquid chromatography-tandem mass spectrometry allowed the identification of 893 different proteins, confirming the reproducible capacity of NPs to increase the number of identified proteins, through a reduction of the sample concentration range and the capture of specific proteins on the three different surfaces. These NP-specific protein signatures revealed significant differences in their isoelectric point and molecular weight. Moreover, this NP strategy offered a deeper access to the erythrocyte proteome highlighting several signaling pathways implicated in important erythrocyte functions. The automated potentiality, the reproducibility, and the low-consuming sample demonstrate the strong compatibility of our strategy for large-scale clinical studies and may become a standardized sample preparation in future erythrocyte-associated proteomics studies.

Lipid composition: a “key factor” for the rational manipulation of the liposome–protein corona by liposome design

When liposomes are exposed to biological fluids, a dynamic protein coating immediately covers them forming a ‘protein corona’. Those proteins can interact with receptors (over)expressed on the plasma membrane of target cells bringing the liposomes to their final destination.

Nanoparticle–blood interactions: the implications on solid tumour targeting

This review examines nanoparticle–blood interactions, their implications on solid tumour targeting, and provides an outlook to guide future nanoparticle design.

Comprehensive analysis of PEGylated liposome-associated proteins relating to the accelerated blood clearance phenomenon by combination with shotgun analysis and conventional methods

PEGylated liposome, sterically stabilized by polyethylene glycol (PEG), results in reduced recognition of the liposome by the mononuclear phagocyte system. Recently, we reported regarding the accelerated blood clearance (ABC) phenomenon that PEGylated liposome is cleared very rapidly from blood circulation upon repeated injection. Anti-PEG IgM production and subsequent complement activation were crucial in causing the ABC phenomenon. However, there still remains the possibility that unknown plasma factors might affect the fate of PEGylated liposome that is subjected to the ABC phenomenon. A label-free approach to shotgun analysis is a great tool for characterizing proteins in a biological system. In this study, therefore, a shotgun analysis was employed to identify plasma protein bound on PEGylated liposome after the ABC phenomenon was induced in the mouse model. The analysis revealed that immunoglobulin and complement components (C1 and C3) are the major proteins. Subsequent analysis with enzyme-linked immunosorbent assay and Western blotting showed that the immunoglobulin was IgM and that the complement system was mainly activated via an anti-PEG IgM-mediated classical pathway. These results support our earlier assumptions-anti-PEG IgM and complement activation were the major causes of the ABC phenomenon. Our proposed analytical strategy would be expected to provide useful information for the development and design of the nanocarrier drug delivery system.

Hyaluronan polymer length, grafting density, and surface poly(ethylene glycol) coating influence in vivo circulation and tumor targeting of hyaluronan-grafted liposomes

Hyaluronan-grafted liposomes (HA-liposomes) preferentially target CD44-overexpressing tumor cells in vitro via receptor-mediated endocytosis. We investigated the pharmacokinetics and biodistribution of HA-liposomes with various sizes of HA (MW 5-8, 50-60, and 175-350 kDa) in mice. Incorporation of negatively charged HA on the liposome surface compromised its blood circulation time, which led to decreased tumor accumulation in CD44+ human breast cancer MDA-MB-231 xenografts compared to PEGylated liposomes (PEG-5000). Clearance of HA-liposomes was HA polymer length-dependent; high MW (175-350 kDa, highest ligand binding affinity) HA-liposomes displayed faster clearance compared to low MW (5-8, 50-60 kDa) HA-liposomes or PEGylated liposomes. Surface HA ligand density can also affect clearance of HA-liposomes. Thus, HA is not an effective stealth coating material. When dual coating of PEG and HA was used, the PEG-HA-liposomes displayed similar blood circulation time and tumor accumulation to that of the PEGylated liposomes; however, the PEG-HA-liposomes displayed better cellular internalization capability in vivo. Tumor histology showed that PEG-HA-liposomes had a more direct association with CD44+ cancer cells, while PEGylated liposomes located predominantly in the tumor periphery, with less association with CD44+ cells. Flow cytometry analysis of ex vivo tumor cells showed that PEG-HA-liposomes had significantly higher tumor cell internalization compared to PEGylated liposomes. This study demonstrates that a long blood circulation time is critical for active tumor targeting. Furthermore, the use of the tumor-targeting ligand HA does not increase total tumor accumulation of actively targeted liposomes in solid tumors; however, it can enhance intracellular delivery.

Protein corona composition of superparamagnetic iron oxide nanoparticles with various physico-chemical properties and coatings

Because of their biocompatibility and unique magnetic properties, superparamagnetic iron oxide nanoparticles NPs (SPIONs) are recognized as some of the most prominent agents for theranostic applications. Thus, understanding the interaction of SPIONs with biological systems is important for their safe design and efficient applications. In this study, SPIONs were coated with 2 different polymers: polyvinyl alcohol polymer (PVA) and dextran. The obtained NPs with different surface charges (positive, neutral, and negative) were used as a model study of the effect of surface charges and surface polymer materials on protein adsorption using a magnetic separator. We found that the PVA-coated SPIONs with negative and neutral surface charge adsorbed more serum proteins than the dextran-coated SPIONs, which resulted in higher blood circulation time for PVA-coated NPs than the dextran-coated ones. Highly abundant proteins such as serum albumin, serotransferrin, prothrombin, alpha-fetoprotein, and kininogen-1 were commonly found on both PVA- and dextran-coated SPIONs. By increasing the ionic strength, soft- and hard-corona proteins were observed on 3 types of PVA-SPIONs. However, the tightly bound proteins were observed only on negatively charged PVA-coated SPIONs after the strong protein elution.

Effect of polyethyleneglycol (PEG) chain length on the bio-nano-interactions between PEGylated lipid nanoparticles and biological fluids: from nanostructure to uptake in cancer cells

When nanoparticles (NPs) enter a physiological environment, medium components compete for binding to the NP surface leading to formation of a rich protein shell known as the "protein corona". Unfortunately, opsonins are also adsorbed. These proteins are immediately recognized by the phagocyte system with rapid clearance of the NPs from the bloodstream. Polyethyleneglycol (PEG) coating of NPs (PEGylation) is the most efficient anti-opsonization strategy. Linear chains of PEG, grafted onto the NP surface, are able to create steric hindrance, resulting in a significant inhibition of protein adsorption and less recognition by macrophages. However, excessive PEGylation can lead to a strong inhibition of cellular uptake and less efficient binding with protein targets, reducing the potential of the delivery system. To reach a compromise in this regard we employed a multi-component (MC) lipid system with uncommon properties of cell uptake and endosomal escape and increasing length of PEG chains. Nano liquid chromatography coupled with tandem mass spectrometry (nanoLC-MS/MS) analysis allowed us to accurately determine the corona composition showing that apolipoproteins are the most abundant class in the corona and that increasing the PEG length reduced the protein adsorption and the liposomal surface affinity for apolipoproteins. Due to the abundance of apolipoproteins, we exploited the "protein corona effect" to deliver cationic liposome-human plasma complexes to human prostate cancer PC3 cells that express a high level of scavenger receptor class B type 1 in order to evaluate the cellular uptake efficiency of the systems used. Combining laser scanning confocal microscopy with flow cytometry analysis in PC3 cells we demonstrated that MC-PEG2k is the best compromise between an anti-opsonization strategy and active targeting and could be a promising candidate to treat prostate cancer in vivo.

Selective targeting capability acquired with a protein corona adsorbed on the surface of 1,2-dioleoyl-3-trimethylammonium propane/DNA nanoparticles

A possible turning point in drug delivery has been recently reached: the protein shell, which covers nanocarriers in vivo, can be used for targeting. Here, we show that nanoparticles can acquire a selective targeting capability with a protein corona adsorbed on the surface. We demonstrate that lipid particles made of 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) and DNA, upon interaction with human plasma components, spontaneously become coated with vitronectin that promotes efficient uptake in cancer cells expressing high levels of the vitronectin ανβ3 integrin receptor.