Biomolecular Corona Research Articles

Link between Low-Fouling and Stealth: A Whole Blood Biomolecular Corona and Cellular Association Analysis on Nanoengineered Particles.

Upon exposure to human blood, nanoengineered particles interact with a multitude of plasma components, resulting in the formation of a biomolecular corona. This corona modulates downstream biological responses, including recognition by and association with human immune cells. Considerable research effort has been directed toward the design of materials that can demonstrate a low affinity for various proteins (low-fouling materials) and materials that can exhibit low association with human immune cells (stealth materials). An implicit assumption common to bio-nano research is that nanoengineered particles that are low-fouling will also exhibit stealth. Herein, we investigated the link between thelow-fouling properties of a particleand its propensity for stealth in whole human blood. High-fouling mesoporous silica (MS) particles and low-fouling zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) particles were synthesized, and their interaction with blood components was assessed before and after precoating with serum albumin, immunoglobulin G, or complement protein C1q. We performed an in-depth proteomics characterization of the biomolecular corona that both identifiesspecific proteinsand measures their relative abundance. This was compared with observations from a whole blood association assay that identified with which cell type each particle system associates. PMPC-based particles displayed reduced association both with cells and with serum proteins compared with MS-based particles. Furthermore, the enrichment of specific proteins within the biomolecular corona was found to correlate with association with specific cell types. This study demonstrates how the low-fouling properties of a material are indicative of its stealth with respect to immune cell association.

Liposome protein corona characterization as a new approach in nanomedicine.

This trends article describes the analytical approaches for the in-depth characterization of the protein corona on liposome nanoparticles. In particular, examples since 2014 are summarized according to the analytical approach. Traditional protein corona characterizations from in vitro static experiments are provided along with the newly introduced experimental setups for characterization of the protein corona by in vitro dynamic and in vivo studies. Additionally, a special attention is also devoted to the need for introduction of new experimental workflows for characterization of a much wider array of biomolecules. In the most recent years, an extension of the protein corona concept to the biomolecular corona was introduced, and the analytical targets are no longer restricted to proteins, but to other important biomolecules as well, as they can potentially affect the biodistribution and interaction of nanoparticles with the biological systems. The few recent examples in this field are discussed for the characterization of metabolites and lipids in the biomolecular corona with examples, also extending the discussion from liposome to other types of nanoparticles. A final discussion is provided on the potential key role of the most recent omics approaches in the study of the nano-bio interface, with an overview on top-down proteomics, which allows a better elucidation of proteoforms, and on lipidomics and metabolomics, which allow a comprehensive untargeted characterization of lipids and metabolites, respectively. Graphical abstract.

Graphene Nanoflake Uptake Mediated by Scavenger Receptors.

The biological interactions of graphene have been extensively investigated over the last 10 years. However, very little is known about graphene interactions with the cell surface and how the graphene internalization process is driven and mediated by specific recognition sites at the interface with the cell. In this work, we propose a methodology to investigate direct molecular correlations between the biomolecular corona of graphene and specific cell receptors, showing that key protein recognition motifs, presented on the nanomaterial surface, can engage selectively with specific cell receptors. We consider the case of apolipoprotein A-I, found to be very abundant in the graphene protein corona, and observe that the uptake of graphene nanoflakes is somewhat increased in cells with greatly elevated expression of scavenger receptors B1, suggesting a possible mechanism of endogenous interaction. The uptake results, obtained by flow cytometry, have been confirmed using Raman microspectroscopic mapping, exploiting the strong Raman signature of graphene.

The biomolecular corona of gold nanoparticles in a controlled microfluidic environment.

Nanoparticles (NPs) exposed to biological media are coated by proteins and other biomolecules forming a biomolecular corona (BC) on the particle surface. Recent studies have shown that shear stress as that created by laminar fluid flow generates more complex coronas with systematic changes in composition with respect to counterparts formed under static incubation. However, in most studies reported so far, dynamic environments have been produced by peristaltic pumps and comparing experimental results appears challenging. On the other side, generating shear stress by microfluidic devices could help to remove user variability and ensure better reproducibility of experimental data. This study was therefore aimed at exploring formation of NP-BC in a microfluidic environment. To this end, 100 nm gold nanoparticles and human plasma (HP) were used as models for nano-formulation and biological medium. We injected gold nanoparticles and HP in each of the islets of a remote-controlled microfluidic cartridge. Static incubation was used as a reference. BC-decorated NPs were thoroughly characterized by dynamic light scattering (DLS), micro-electrophoresis (ME), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) and nano-liquid chromatography tandem mass spectrometry (nano-LC MS/MS). By varying the incubation time from 30 s to 2.5 min we demonstrate that BC is already determined by the earliest exposure time point and does not appreciably evolve in time. DLS and ME results demonstrate that the BC formed in a microfluidic chip is thicker and more negatively charged than its counterpart formed under static incubation. SDS-PAGE and nano-LC MS/MS revealed that the incubation procedure had a major effect on BC composition. As an example, immunoglobulins are the most abundant plasma proteins of the BC generated in a microfluidic environment (relative protein abundance ∼30%), while tissue leakage proteins (relative protein abundance ∼26%) are the most enriched proteins when the BC is formed upon static incubation. Potential implications in emerging biomedical research arenas are discussed.

Effect of molecular crowding on the biological identity of liposomes: an overlooked factor at the bio-nano interface.

Once embedded in a physiological environment, the surface of nanoparticles (NPs) gets covered with a biomolecular corona (BC) that alters their synthetic characteristics and subsequently gives them a peculiar biological identity. Despite recent studies having clarified the role of NP composition, surface chemistry and biological source (e.g., human/animal serum or plasma) in the formation of the BC, little is known about the possible impact of molecular crowding. To fill this gap, we used a cationic liposomal formulation as a model system and studied its biological identity upon incubation with human plasma, at a fixed liposome-to-plasma volume ratio and different concentrations. We carried out dynamic light scattering measurements to quantify the size and zeta potential of the investigated systems and gel electrophoresis to evaluate the composition of the corresponding coronas. Our findings suggest that NP stability may be compromised by molecular crowding, but the corona composition is stable over a wide range of concentrations, which extend over more than two orders of magnitude. As the biological identity of NPs eventually determines their final fate in vivo, we predict that this study could contribute to the development of a safe and effective nanosystem for the targeted delivery of therapeutic agents.

Streptomycin functionalization on silver nanoparticles for improved antibacterial activity

The global health care system is facing a major threat due to the increase in the antibiotic resistant bacterial strains. Hence, there is an urgent need to develop new antimicrobial representatives to overcome the incompetence of the conventional antibiotics. In this study, we report the green synthesis of a range of silver (Ag) nanoparticles engaging tyrosine, tryptophan, curcumin or epigallocatechin gallate (EGCG). Further, the Ag nanoparticles were surface functionalized by streptomycin to develop an efficient biomolecular surface corona and to enhance antibacterial competency of all these Ag nanoparticles. The antibacterial potentials of as-synthesized Ag nanoparticles and post-functionalized Ag nanoparticles were tested against Gram-positive and Gram-negative bacterial strains as proof of concept. The results signpost that the bacterial viability for both the Gram-strains decreased after treatment with streptomycin functionalized Ag nanoparticles compare to as-synthesized Ag nanoparticles. The enhanced antibacterial potential of the streptomycin functionalized Ag nanoparticles and conjugation of inorganic (Ag)/organic (streptomycin and tyrosine, tryptophan, curcumin or EGCG) materials in a single system may open new opportunities even to overcome antibiotic resistance. Therefore, the study highlights that the surface functionalization approach can be extended to other metal nanoparticles and different antibiotics to combat bacterial drug resistance.

<p>Silver nanoparticles: aggregation behavior in biorelevant conditions and its impact on biological activity</p>

PurposeThe biomedical applications of silver nanoparticles (AgNPs) are heavily investigated due to their cytotoxic and antimicrobial properties. However, the scientific literature is lacking in data on the aggregation behavior of nanoparticles, especially regarding its impact on biological activity. Therefore, to assess the potential of AgNPs in therapeutic applications, two different AgNP samples were compared under biorelevant conditions.MethodsCitrate-capped nanosilver was produced by classical chemical reduction and stabilization with sodium citrate (AgNP@C), while green tea extract was used to produce silver nanoparticles in a green synthesis approach (AgNP@GTs). Particle size, morphology, and crystallinity were characterized using transmission electron microscopy. To observe the effects of the most important biorelevant conditions on AgNP colloidal stability, aggregation grade measurements were carried out using UV-Vis spectroscopy and dynamic light scatterig, while MTT assay and a microdilution method were performed to evaluate the effects of aggregation on cytotoxicity and antimicrobial activity in a time-dependent manner.ResultsThe aggregation behavior of AgNPs is mostly affected by pH and electrolyte concentration, while the presence of biomolecules can improve particle stability due to the biomolecular corona effect. We demonstrated that high aggregation grade in both AgNP samples attenuated their toxic effect toward living cells. However, AgNP@GT proved less prone to aggregation thus retained a degree of its toxicity.ConclusionTo our knowledge, this is the first systematic examination regarding AgNP aggregation behavior with simultaneous measurements of its effect on biological activity. We showed that nanoparticle behavior in complex systems can be estimated by simple compounds like sodium chloride and glutamine. Electrostatic stabilization might not be suitable for biomedical AgNP applications, while green synthesis approaches could offer new frontiers to preserve nanoparticle toxicity by enhancing colloidal stability. The importance of properly selected synthesis methods must be emphasized as they profoundly influence colloidal stability, and therefore biological activity.

Graphene oxide touches blood: in vivo interactions of bio-coronated 2D materials.

Graphene oxide is the hot topic in biomedical and pharmaceutical research of the current decade. However, its complex interactions with human blood components complicate the transition from the promising in vitro results to clinical settings. Even though graphene oxide is made with the same atoms as our organs, tissues and cells, its bi-dimensional nature causes unique interactions with blood proteins and biological membranes and can lead to severe effects like thrombogenicity and immune cell activation. In this review, we will describe the journey of graphene oxide after injection into the bloodstream, from the initial interactions with plasma proteins to the formation of the "biomolecular corona", and biodistribution. We will consider the link between the chemical properties of graphene oxide (and its functionalized/reduced derivatives), protein binding and in vivo response. We will also summarize data on biodistribution and toxicity in view of the current knowledge of the influence of the biomolecular corona on these processes. Our aim is to shed light on the unsolved problems regarding the graphene oxide corona to build the groundwork for the future development of drug delivery technology.

Converting the personalized biomolecular corona of graphene oxide nanoflakes into a high-throughput diagnostic test for early cancer detection.

Advances in nanotechnology are introducing the exciting possibility of cancer identification at early stages via analysis of the personalized biomolecular corona (BC), i.e. the dynamic "halo" of proteins that adsorbs onto NPs following exposure to patients' plasma. In this study, we develop a blood test for early cancer detection based on the characterization of the BC that forms around Graphene Oxide (GO) nanoflakes. Among its elective properties, GO binds low amounts of albumin, the most abundant protein in the blood and one of the most enriched proteins in the BC of many nanomaterials. This unique property of GO allows strong adsorption of poorly concentrated plasma proteins without abundant protein depletion. In our study, GO nanometric flakes have been used to analyze BCs from 50 subjects, half of them diagnosed with pancreatic cancer and half of them being healthy volunteers. Pancreatic cancer was chosen as the model of a high mortality disease with poor survival rates due to its delayed diagnosis. The receiver operating characteristic (ROC) curve analysis was applied to measure the diagnostic accuracy of the BC-based test. We obtained an area under the curve (AUC) of 0.96 and the test discriminated cancer patients from healthy subjects with a sensitivity of 92%. Finally, a double-blind validation was made using a second test dataset (10 healthy subjects + 10 pancreatic cancer patients) and it confirmed the results obtained on the first training dataset. Being highly accurate, fast, inexpensive and easy to perform, we believe that the BC-enabled blood test has the potential to become a turning point in early detection of cancer and other diseases.

The Crown and the Scepter: Roles of the Protein Corona in Nanomedicine.

Engineering nanomaterials are increasingly considered promising and powerful biomedical tools or devices for imaging, drug delivery, and cancer therapies, but few nanomaterials have been tested in clinical trials. This wide gap between bench discoveries and clinical application is mainly due to the limited understanding of the biological identity of nanomaterials. When they are exposed to the human body, nanoparticles inevitably interact with bodily fluids and thereby adsorb hundreds of biomolecules. A "biomolecular corona" forms on the surface of nanomaterials and confers a new biological identity for NPs, which determines the following biological events: cellular uptake, immune response, biodistribution, clearance, and toxicity. A deep and thorough understanding of the biological effects triggered by the protein corona in vivo will speed up their translation to the clinic. To date, nearly all studies have attempted to characterize the components of protein coronas depending on different physiochemical properties of NPs. Herein, recent advances are reviewed in order to better understand the impact of the biological effects of the nanoparticle-corona on nanomedicine applications. The recent development of the impact of protein corona formation on the pharmacokinetics of nanomedicines is also highlighted. Finally, the challenges and opportunities of nanomedicine toward future clinical applications are discussed.

Nanoparticle-biomolecular corona: A new approach for the early detection of non-small-cell lung cancer.

Lung cancer (LC) is the most common type of cancer and the second cause of death worldwide in men and women after cardiovascular diseases. Non-small-cell lung cancer (NSCLC) is the most frequent type of LC occurring in 85% of cases. Developing new methods for early detection of NSCLC could substantially increase the chances of survival and, therefore, is an urgent task for current research. Nowadays, explosion in nanotechnology offers unprecedented opportunities for therapeutics and diagnosis applications. In this context, exploiting the bio-nano-interactions between nanoparticles (NPs) and biological fluids is an emerging field of research. Upon contact with biofluids, NPs are covered by a biomolecular coating referred to as "biomolecular corona" (BC). In this study, we exploitedBC for discriminating between NSCLC patients and healthy volunteers. Blood samples from 10 NSCLC patients and 5 subjects without malignancy were allowed to interact with negatively charged lipid NPs, leading to the formation of a BC at the NP surface. After isolation, BCs were characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). We found that the BCs of NSCLC patients was significantly different from that of healthy individuals. Statistical analysis of SDS-PAGE results allowed discriminating between NSCLC cancer patients and healthy subjects with 80% specificity, 80% sensitivity and a total discriminate correctness rate of 80%. While the results of the present investigation cannot be conclusive due to the small size of the data set, we have shown that exploitation of the BC is a promising approach for the early diagnosis of NSCLC.

Towards Utilising Photocrosslinking of Polydiacetylenes for the Preparation of "Stealth" Upconverting Nanoparticles.

We demonstrate a novel strategy for preparing hydrophilic upconverting nanoparticles (UCNPs) by harnessing the photocrosslinking ability of diacetylenes. Replacement of the hydrophobic oleate coating on the UCNPs with 10,12-pentacosadiynoic acid, followed by overcoating with diacetylene phospholipid and subsequent photocrosslinking under 254 nm irradiation produces water-dispersible polydiacetylene-coated UCNPs. These UCNPs resist the formation of a biomolecular corona and show great colloidal stability. Furthermore, amine groups on the diacetylene phospholipid allow for functionalisation of the UCNPs with, for example, radiolabels or targeting moieties. These results demonstrate that this new surface-coating method has great potential for use in the preparation of UCNPs with improved biocompatibility.

Towards Utilising Photocrosslinking of Polydiacetylenes for the Preparation of “Stealth” Upconverting Nanoparticles

AbstractWe demonstrate a novel strategy for preparing hydrophilic upconverting nanoparticles (UCNPs) by harnessing the photocrosslinking ability of diacetylenes. Replacement of the hydrophobic oleate coating on the UCNPs with 10,12‐pentacosadiynoic acid, followed by overcoating with diacetylene phospholipid and subsequent photocrosslinking under 254 nm irradiation produces water‐dispersible polydiacetylene‐coated UCNPs. These UCNPs resist the formation of a biomolecular corona and show great colloidal stability. Furthermore, amine groups on the diacetylene phospholipid allow for functionalisation of the UCNPs with, for example, radiolabels or targeting moieties. These results demonstrate that this new surface‐coating method has great potential for use in the preparation of UCNPs with improved biocompatibility.

Effect of Glucose on Liposome-Plasma Protein Interactions: Relevance for the Physiological Response of Clinically Approved Liposomal Formulations.

Recently, the concept is emerging that the reduced success of nanoparticles in clinical practice is due to the adsorption of the "biomolecular corona (BC)," which alters their biological identity. Apart from protein variations, alterations in the human metabolome may change the BC decoration, which has poorly been addressed so far. Here, glucose is used as a model metabolite and how the interactions between liposomes (as a model nanoparticle) and plasma proteins are influenced by normal and diabetic sugar blood levels is explored. As model liposomes, Doxoves and Onivyde are used that are used for the treatment of breast and metastatic pancreatic cancer, respectively. It is shown that glucose does affect the structure and composition of BC. The biological effects of liposome-BC complexes are investigated in MCF 7 and MDA-MB-231 breast cancer cells for Doxoves and in pancreatic adenocarcinoma (PANC-1) and insulinoma (INS-1) cells for Onivyde. In the presence of glucose, the cellular toxicity of liposome-protein complexes and uptake by human monocytic THP1 cell line increases. These results demonstrate that alterations in glucose concentration, and more generally changes in the human metabolome, may play a fundamental role in the biological identity of liposomes and, consequently, on their in vivo physiological readouts including therapeutic efficacy.

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.

Transformation and Speciation Analysis of Silver Nanoparticles of Dietary Supplement in Simulated Human Gastrointestinal Tract.

Knowledge of the physicochemical properties of ingestible silver nanoparticles (AgNPs) in the human gastrointestinal tract (GIT) is essential for assessing their bioavailability, bioactivity, and potential health risks. The gastrointestinal fate of AgNPs and silver ions from a commercial dietary supplement was therefore investigated using a simulated human GIT. In the mouth, no dissolution or aggregation of AgNPs occurred, which was attributed to the neutral pH and the formation of biomolecular corona, while the silver ions formed complexes with biomolecules (Ag-biomolecule). In the stomach, aggregation of AgNPs did not occur, but extensive dissolution was observed due to the low pH and the presence of Cl-. In the fed state (after meal), 72% AgNPs (by mass) dissolved, with 74% silver ions forming Ag-biomolecule and 26% forming AgCl. In the fasted state (before meal), 76% AgNPs dissolved, with 82% silver ions forming Ag-biomolecule and 18% forming AgCl. A biomolecular corona around AgNPs, comprised of mucin with multiple sulfhydryl groups, inhibited aggregation and dissolution of AgNPs. In the small intestine, no further dissolution or aggregation of AgNPs occurred, while the silver ions existed only as Ag-biomolecule. These results provide useful information for assessing the bioavailability of ingestible AgNPs and their subsequently potential health risks, and for the safe design and utilization of AgNPs in biomedical applications.

Nervous System Injury in Response to Contact With Environmental, Engineered and Planetary Micro- and Nano-Sized Particles.

Nerve cells take a special place among other cells in organisms because of their unique function mechanism. The plasma membrane of nerve cells from the one hand performs a classical barrier function, thereby being foremost targeted during contact with micro- and nano-sized particles, and from the other hand it is very intensively involved in nerve signal transmission, i.e., depolarization-induced calcium-dependent compound exocytosis realized via vesicle fusion following by their retrieval and calcium-independent permanent neurotransmitter turnover via plasma membrane neurotransmitter transporters that utilize Na+/K+ electrochemical gradient as a driving force. Worldwide traveling air pollution particulate matter is now considered as a possible trigger factor for the development of a variety of neuropathologies. Micro- and nano-sized particles can reach the central nervous system during inhalation avoiding the blood–brain barrier, thereby making synaptic neurotransmission extremely sensitive to their influence. Neurosafety of environmental, engineered and planetary particles is difficult to predict because they possess other features as compared to bulk materials from which the particles are composed of. The capability of the particles to absorb heavy metals and organic neurotoxic molecules from the environment, and moreover, spontaneously interact with proteins and lipids in organisms and form biomolecular corona can considerably change the particles‘ features. The absorption capability occasionally makes them worldwide traveling particulate carriers for delivery of environmental neurotoxic compounds to the brain. Discrepancy of the experimental data on neurotoxicity assessment of micro- and nano-sized particles can be associated with a variability of systems, in which neurotoxicity was analyzed and where protein components of the incubation media forming particle biocorona can significantly distort and even eliminate factual particle effects. Specific synaptic mechanisms potentially targeted by environmental, engineered and planetary particles, general principles of particle neurosafety and its failure were discussed. Particle neurotoxic potential depends on their composition, size, shape, surface properties, stability in organisms and environment, capability to absorb neurotoxic compounds, form dust and interrelate with different biomolecules. Changes in these parameters can break primary particle neurosafety.

Pre-adsorption of antibodies enables targeting of nanocarriers despite a biomolecular corona.

To promote drug delivery to exact sites and cell types, the surface of nanocarriers is functionalized with targeting antibodies or ligands, typically coupled by covalent chemistry. Once the nanocarrier is exposed to biological fluid such as plasma, however, its surface is inevitably covered with various biomolecules forming the protein corona, which masks the targeting ability of the nanoparticle. Here, we show that we can use a pre-adsorption process to attach targeting antibodies to the surface of the nanocarrier. Pre-adsorbed antibodies remain functional and are not completely exchanged or covered by the biomolecular corona, whereas coupled antibodies are more affected by this shielding. We conclude that pre-adsorption is potentially a versatile, efficient and rapid method of attaching targeting moieties to the surface of nanocarriers.

Human Biomolecular Corona of Liposomal Doxorubicin: The Overlooked Factor in Anticancer Drug Delivery.

More than 20 years after its approval by the Food and Drug Administration (FDA), liposomal doxorubicin (DOX) is still the drug of choice for the treatment of breast cancer and other conditions such as ovarian cancer and multiple myeloma. Yet, despite the efforts, liposomal DOX did not satisfy expectations at the clinical level. When liposomal drugs enter a physiological environment, their surface gets coated by a dynamic biomolecular corona (BC). The BC changes liposome's synthetic identity, providing it with a new one, referred to as "biological identity" (size, aggregation state, and BC composition). Today, the concept is emerging that specific BCs may determine either success (e.g., stealth effect and accumulation at the target site) or failure (e.g., rapid blood clearance and off-target interactions) of liposomal drugs. To get a comprehensive investigation of liposome synthetic identity, biological identity, and cellular response as a function of human plasma (HP) concentration, here we used a straightforward combination of quantitative analytical and imaging tools, including dynamic light scattering, microelectrophoresis, synchrotron small-angle X-ray scattering, transmission electron microscopy (TEM), fluorescence lifetime imaging microscopy (FLIM), nano-liquid chromatography tandem mass spectrometry/mass spectrometry (nano-LC-MS/MS), confocal microscopy, flow cytometry, and cell viability assays. Doxoves was selected as a reference. Following exposure to HP, Doxoves was surrounded by a complex BC that changed liposome's synthetic identity. Observations made with nano-LC-MS/MS revealed that the BC of Doxoves did not evolve as a function of HP concentration and was poorly enriched of typical "opsonins" (complement proteins, immunoglobulins, etc.). This provides a possible explanation for the prolonged blood circulation of liposomal DOX. On the other hand, flow cytometry showed that protein binding reduced the internalization of DOX in MCF7 and MDA-MB-435S human breast carcinoma. Combining FLIM and TEM experiments, we clarified that reduction in DOX intracellular content was likely due to the frequent rupture of the liposome membrane and consequent leakage of the cargo. In light of reported results, we are prompted to speculate that a detailed understanding of BC formation, composition, and effects on liposome stability and uptake is an indispensable task of future research in the field, especially along the way to clinical translation of liposomal drugs.

Computational Investigations of the Interaction between the Cell Membrane and Nanoparticles Coated with a Pulmonary Surfactant.

When inhaled nanoparticles (NPs) come into the deep lung, they develop a biomolecular corona by interacting with the pulmonary surfactant. The adsorption of the phospholipids and proteins gives a new biological identity to the NPs, which may alter their subsequent interactions with cells and other biological entities. Investigations of the interaction between the cell membrane and NPs coated with such a biomolecular corona are important in understanding the role of the biofluids on cellular uptake and estimating the dosing capacity and the nanotoxicology of NPs. In this paper, using dissipative particle dynamics, we investigate how the physicochemical properties of the coating pulmonary surfactant lipids and proteins affect the membrane response for inhaled NPs. We pinpoint several key factors in the endocytosis of lipid NPs, including the deformation of the coating lipids, coating lipid density, and ligand-receptor binding strength. Further studies reveal that the deformation of the coating lipids consumes energy but on the other hand promotes the coating ligands to bind with receptors more tightly. The coating lipid density controls the amount of the ligands as well as the hydrophobicity of the lipid NPs, thus affecting the endocytosis kinetics through the specific and nonspecific interactions. It is also found that the hydrophobic surfactant proteins associated with lipids can accelerate the endocytosis process of the NPs, but the endocytosis efficiency mainly depends on the density of the coating surfactant lipids. These findings can help understand how the pulmonary surfactant alters the biocompatibility of the inhaled NPs and provide some guidelines in designing an NP complex for efficient pulmonary drug delivery.