The Protein Corona of PEGylated PGMA-Based Nanoparticles is Preferentially Enriched with Specific Serum Proteins of Varied Biological Function

Differential cellular responses to FDA-approved nanomedicines: an exploration of albumin-based nanocarriers and liposomes in protein corona formation

Albumin nanoparticles (NPs) and PEGylated liposomes have garnered tremendous interest as therapeutic drug carriers due to their unique physicochemical properties. These unique properties also have significant effects on the composition and structure of the protein corona formed around these NPs in a biological environment. Herein, protein corona formation on albumin NPs and liposomes was simultaneously evaluated through in vitro and simulation studies. The sizes of both types of NPs increased with more negatively charged interfaces upon being introduced into fetal bovine serum. Gel electrophoresis and label-free quantitative proteomics were performed to identify proteins recruited to the hard corona, and fewer proteins were found in albumin NPs than in liposomes, which is in accordance with isothermal titration calorimetry. The cellular uptake efficiency of the two NPs significantly differed in different serum concentrations, which was further scrutinized by loading an anticancer compound into albumin NPs. The presence of the hard protein corona increased the cellular uptake of albumin NPs in comparison with liposomes. In our simulation study, a specific receptor present in the membrane was greatly attracted to the albumin-apolipoprotein E complex. Overall, this study not only evaluated protein corona formation on albumin NPs, but also made promising advancements toward albumin- and liposome-based therapeutic systems.

Concentration and composition of the protein corona as a function of incubation time and serum concentration: an automated approach to the protein corona

Nanoparticles in contact with proteins form a "corona" of proteins adsorbed on the nanoparticle surface. Subsequent biological responses are then mediated by the adsorbed proteins rather than the bare nanoparticles. The use of nanoparticles as nanomedicines and biosensors would be greatly improved if researchers were able to predict which specific proteins will adsorb on a nanoparticle surface. We use a recently developed automated workflow with a liquid handling robot and low-cost proteomics to determine the concentration and composition of the protein corona formed on carboxylate-modified iron oxide nanoparticles (200 nm) as a function of incubation time and serum concentration. We measure the concentration of the resulting protein corona with a colorimetric assay and the composition of the corona with proteomics, reporting both abundance and enrichment relative to the fetal bovine serum (FBS) proteins used to form the corona. Incubation time was found to be an important parameter for corona concentration and composition at high (100% FBS) incubation concentrations, with only a slight effect at low (10%) FBS concentrations. In addition to these findings, we describe two methodological advances to help reduce the cost associated with protein corona experiments. We have automated the digest step necessary for proteomics and measured the variability between triplicate samples at each stage of the proteomics experiments. Overall, these results demonstrate the importance of understanding the multiple parameters that influence corona formation, provide new tools for corona characterization, and advance bioanalytical research in nanomaterials.

An overview on the exploring the interaction of inorganic nanoparticles with microtubules for the advancement of cancer therapeutics

Targeting microtubules (MTs), dynamic and stable proteins in cells, by different ligands have been reported to be a potential strategy to combat cancer cells. Inorganic nanoparticles (NPs) have been widely used as anticancer, antibacterial, and free radical scavenging agents, where the come in contact with biological macromolecules. The interaction between the NPs and biological macromolecules like MTs frequently occurs through different mechanisms. A prerequisite for a detailed exploration of MT structures and functions for biomedical applications like cancer therapy is to investigate profoundly the mechanisms involved in MT-NP interactions, for which the full explanation and characterization of the parameters that are responsible for the formation of a NP-protein complex are crucial. Therefore, in view of the fact that the goal of the rational NP-based future drug design and new therapies is to rely on the information of the structural details and protein-NPs binding mechanisms to manipulate the process of developing new potential drugs, a comprehensive investigation of the essence of the molecular recognition/interaction is also of considerable importance. In the present review, first, the microtubule (MT) structure and its binding sites upon interaction with MT stabilizing agents (MSAs) and MT destabilizing agents (MDAs) are introduced and rationalized. Next, MT targeting in cancer therapy and interaction of NPs with MTs are discussed. Furthermore, interaction of NPs with proteins and the manipulation of protein corona (PC), experimental techniques, and direct interaction of NPs with MTs, are discussed, and finally the challenges and future perspective of the field are introduced. We envision this review can provide useful information on the manipulation of the MT lattice for the progress of cancer nanomedicine.

Impact of dynamic sub-populations within grafted chains on the protein binding and colloidal stability of PEGylated nanoparticles

Polyethylene glycol grafting has played a central role in preparing the surfaces of nano-probes for biological interaction, to extend blood circulation times and to modulate protein recognition and cellular uptake. However, the role of PEG graft dynamics and conformation in determining surface recognition processes is poorly understood primarily due to the absence of a microscopic picture of the surface presentation of the polymer. Here a detailed NMR analysis reveals three types of dynamic ethylene glycol units on PEG-grafted SiO2 nanoparticles (NPs) of the type commonly evaluated as long-circulating theranostic nano-probes; a narrow fraction with fast dynamics associated with the chain ends; a broadened fraction spectrally overlapped with the former arising from those parts of the chain experiencing some dynamic restriction; and a fraction too broad to be observed in the spectrum arising from units closer to the surface/graft which undergo slow motion on the NMR timescale. We demonstrate that ethylene glycol units transition between fractions as a function of temperature, core size, PEG chain length and surface coverage and demonstrate how this distribution affects colloidal stability and protein uptake. The implications of the findings for biological application of grafted nanoparticles are discussed in the context of accepted models for surface ligand conformation.

Functionalized PLGA nanoparticles prepared by nano-emulsion templating interact selectively with proteins involved in the transport through the blood-brain barrier

During the last few decades, extensive efforts has been made to design nanocarriers to transport drugs into the central nervous system (CNS). However, its efficacy is limited due to the presence of the Blood-Brain Barrier (BBB) which greatly reduces drug penetration making Drug Delivery Systems (DDS) necessary. Polymeric nanoparticles (NPs) have been reported to be appropriate for this purpose and in particular, poly(lactic-co-glycolic acid) (PLGA) has been used for its ability to entrap small molecule drugs with great efficiency and the ease with which it functionalizes NPs. Despite the fact that their synthetic identity has been studied in depth, the biological identity of such manufactured polymers still remains unknown as does their biodistribution and in vivo fate. This biological identity is a result of their interaction with blood proteins, the so-called "protein corona" which tends to alter the behavior of polymeric nanoparticles in the body. The aim of the present research is to identify the proteins bounded to polymeric nanoparticles designed to selectively interact with the BBB. For this purpose, four different PLGA NPs were prepared and analyzed: (i) "PLGA@Drug," in which a model drug was encapsulated in its core; (ii) "8D3-PLGA" NPs where the PLGA surface was functionalized with a monoclonal anti-transferrin receptor antibody (8D3 mAb) in order to specifically target the BBB; (iii) "8D3-PLGA@Drug" in which the PLGA@Drug surface was functionalized using the same antibody described above and (iv) bare PLGA NPs which were used as a control. Once the anticipated protein corona NPs were obtained, proteins decorating both bare and functionalized PLGA NPs were isolated and analyzed. Apart from the indistinct interaction with PLGA NPs with the most abundant serum proteins, specific proteins could also be identified in the case of functionalized PLGA NPs. These findings may provide valuable insight into designing novel vehicles based on PLGA NPs for crossing the BBB.

Recent Advances in Understanding the Protein Corona of Nanoparticles and in the Formulation of "Stealthy" Nanomaterials

In the last decades, the staggering progress in nanotechnology brought around a wide and heterogeneous range of nanoparticle-based platforms for the diagnosis and treatment of many diseases. Most of these systems are designed to be administered intravenously. This administration route allows the nanoparticles (NPs) to widely distribute in the body and reach deep organs without invasive techniques. When these nanovectors encounter the biological environment of systemic circulation, a dynamic interplay occurs between the circulating proteins and the NPs, themselves. The set of proteins that bind to the NP surface is referred to as the protein corona (PC). PC has a critical role in making the particles easily recognized by the innate immune system, causing their quick clearance by phagocytic cells located in organs such as the lungs, liver, and spleen. For the same reason, PC defines the immunogenicity of NPs by priming the immune response to them and, ultimately, their immunological toxicity. Furthermore, the protein corona can cause the physical destabilization and agglomeration of particles. These problems induced to consider the PC only as a biological barrier to overcome in order to achieve efficient NP-based targeting. This review will discuss the latest advances in the characterization of PC, development of stealthy NP formulations, as well as the manipulation and employment of PC as an alternative resource for prolonging NP half-life, as well as its use in diagnostic applications.

Isolation methods for particle protein corona complexes from protein-rich matrices

Background: Nanoparticles become rapidly encased by a protein layer when they are in contact with biological fluids. This protein shell is called a corona. The composition of the corona has a strong influence on the surface properties of the nanoparticles. It can affect their cellular interactions, uptake and signaling properties. For this reason, protein coronae are investigated frequently as an important part of particle characterization. Main body of the abstract: The protein corona can be analyzed by different methods, which have their individual advantages and challenges. The separation techniques to isolate corona-bound particles from the surrounding matrices include centrifugation, magnetism and chromatographic methods. Different organic matrices, such as blood, blood serum, plasma or different complex protein mixtures, are used and the approaches vary in parameters such as time, concentration and temperature. Depending on the investigated particle type, the choice of separation method can be crucial for the subsequent results. In addition, it is important to include suitable controls to avoid misinterpretation and false-positive or false-negative results, thus allowing the achievement of a valuable protein corona analysis result. Conclusion: Protein corona studies are an important part of particle characterization in biological matrices. This review gives a comparative overview about separation techniques, experimental parameters and challenges which occur during the investigation of the protein coronae of different particle types.

Protein corona formation moderates the release kinetics of ion channel antagonists from transferrin-functionalized polymeric nanoparticles

Transferrin (Tf)-functionalized p(HEMA-ran-GMA) nanoparticles were designed to incorporate and release a water-soluble combination of three ion channel antagonists, namely zonampanel monohydrate (YM872), oxidized adenosine triphosphate (oxATP) and lomerizine hydrochloride (LOM) identified as a promising therapy for secondary degeneration that follows neurotrauma. Coupled with a mean hydrodynamic size of 285 nm and near-neutral surface charge of −5.98 mV, the hydrophilic nature of the functionalized polymeric nanoparticles was pivotal in effectively encapsulating the highly water soluble YM872 and oxATP, as well as lipophilic LOM dissolved in water-based medium, by a back-filling method. Maximum loading efficiencies of 11.8 ± 1.05% (w/w), 13.9 ± 1.50% (w/w) and 22.7 ± 4.00% (w/w) LOM, YM872 and oxATP respectively were reported. To obtain an estimate of drug exposure in vivo, drug release kinetics assessment by HPLC was conducted in representative physiological milieu containing 55% (v/v) human serum at 37 °C. In comparison to serum-free conditions, it was demonstrated that the inevitable adsorption of serum proteins on the Tf-functionalized nanoparticle surface as a protein corona impeded the rate of release of LOM and YM872 at both pH 5 and 7.4 over a period of 1 hour. While the release of oxATP from the nanoparticles was detectable for up to 30 minutes under serum-free conditions at pH 7.4, the presence of serum proteins and a slightly acidic environment impaired the detection of the drug, possibly due to its molecular instability. Nevertheless, under representative physiological conditions, all three drugs were released in combination from Tf-functionalized p(HEMA-ran-GMA) nanoparticles and detected for up to 20 minutes. Taken together, the study provided enhanced insight into potential physiological outcomes in the presence of serum proteins, and suggests that p(HEMA-ran-GMA)-based therapeutic nanoparticles may be promising drug delivery vehicles for CNS therapy.

Transferrin (Tf)-functionalized p(HEMA-ran-GMA) nanoparticles were designed to incorporate and release a water-soluble combination of three ion channel antagonists, identified as a promising therapy for secondary degeneration following neurotrauma.

Interfacial and Aggregation Behavior of Dicarboxylic Amino Acid-Based Surfactants in Combination with a Cationic Surfactant

The interfacial and micellization behavior of three dicarboxylic amino acid-based anionic surfactants, abbreviated as AAS (N-dodecyl derivative of -aminomalonate, -aspartate, and -glutamate) in combination with hexadecyltrimethylammonium bromide (HTAB) were investigated by surface tension, conductance, UV-vis absorption/emission spectroscopy, dynamic light scattering (DLS), and viscosity studies. Critical micelle concentration (CMC) values of the surfactant mixtures are significantly lower than the predicted values, indicating associative interaction between the components. Surface excess, limiting molecular area, surface pressure at the CMC, and Gibbs free energy indicate spontaneity of the micellization processes compared to the pure components. CMC values were also determined from the sigmoidal variation in the plot of micellar polarity and pyrene UV-vis absorption/emission intensities with surfactant concentration. The aggregation number, determined by static fluorescence quenching method, increases with decreasing mole fraction of the AAS (α_AAS), where the micelles are mainly dominated by the HTAB molecules. The size of the micelle increases with decreasing α_AAS, leading to the formation of larger and complex aggregates, as also supported by the viscosity studies. Micelles comprising 20-40 mol % AAS are highly viscous, in consonance with their sizes. Some of the mixed surfactant systems show unusual viscosity (shear thickening and increased viscosity with increasing temperature). Such mixed surfactant systems are considered to have potential in gel-based drug delivery and nanoparticle synthesis.

Novel Hydrophilic Copolymer-Based Nanoparticle Enhances the Therapeutic Efficiency of Doxorubicin in Cultured MCF-7 Cells

Nanoparticle drug delivery applications have predominantly focused on the entrapment and delivery of hydrophobic molecules with poor water solubility. However, benefits can also be obtained from nanoparticle-based delivery of hydrophilic therapeutics. This study reports on the development of a p(HEMA-ran-GMA)-based nanoparticle synthesized via a spontaneous water-in-oil inverse nanoemulsion to deliver doxorubicin, a water-soluble chemotherapeutic. High drug loading efficiency and sustained release of doxorubicin from Cy5-functionalized p(HEMA-ran-GMA) nanoparticles enabled effective inhibition of the MCF-7 human breast cancer derived cell line. Direct comparative analyses with a hydrophobic PGMA nanoparticle demonstrated enhanced capabilities of the p(HEMA-ran-GMA)-based nanoparticle in vitro. The results suggest that p(HEMA-ran-GMA)-based nanoparticles, which are better suited for hydrophilic drug loading and delivery, may have the potential for the improved therapeutic effect in vivo by enhanced permeation and retention of the nanoparticles by avoidance of off-site side effects of the chemotherapeutic.

Physicochemical Characterization of FRET-Labelled Chitosan Nanocapsules and Model Degradation Studies

Sub-micron o/w emulsions coated with chitosan have been used for drug delivery, quorum sensing inhibition, and vaccine development. To study interactions with biological systems, nanocapsules have been fluorescently labelled in previous works, but it is often difficult to distinguish the released label from intact nanocapsules. In this study, we present advanced-labelling strategies based on Förster Resonance Energy Transfer (FRET) measurements for chitosan-coated nanocapsules and investigate their dissolution and degradation. We used FRET measurements of nanocapsules loaded with equimolar concentrations of two fluorescent dyes in their oily core and correlated them with dynamic light scattering (DLS) count rate measurement and absorbance measurements during their disintegration by dissolution. Using count rate measurements, we also investigated the enzymatic degradation of nanocapsules using pancreatin and how protein corona formation influences their degradation. Of note, nanocapsules dissolved in ethanol, while FRET decreased simultaneously with count rate, and absorbance was caused by nanocapsule turbidity, indicating increased distance between dye molecules after their release. Nanocapsules were degradable by pancreatin in a dose-dependent manner, and showed a delayed enzymatic degradation after protein corona formation. We present here novel labelling strategies for nanocapsules that allow us to judge their status and an in vitro method to study nanocapsule degradation and the influence of surface characteristics.

Protein-Corona-by-Design in 2D: A Reliable Platform to Decode Bio-Nano Interactions for the Next-Generation Quality-by-Design Nanomedicines

Hard corona (HC) protein, i.e., the environmental proteins of the biological medium that are bound to a nanosurface, is known to affect the biological fate of a nanomedicine. Due to the size, curvature, and specific surface area (SSA) 3-factor interactions inherited in the traditional 3D nanoparticle, HC-dependent bio-nano interactions are often poorly probed and interpreted. Here, the first HC-by-design case study in 2D is demonstrated that sequentially and linearly changes the HC quantity using functionalized graphene oxide (GO) nanosheets. The HC quantity and HC quality are analyzed using NanoDrop and label-free liquid chromatography-mass spectrometry (LC-MS) followed by principal component analysis (PCA). Cellular responses (uptake and cytotoxicity in J774 cell model) are compared using imaging cytometry and the modified lactate dehydrogenase assays, respectively. Cellular uptake linearly and solely correlates with HC quantity (R2 = 0.99634). The nanotoxicity, analyzed by retrospective design of experiment (DoE), is found to be dependent on the nanomaterial uptake (primary), HC composition (secondary), and nanomaterial exposure dose (tertiary). This unique 2D design eliminates the size-curvature-SSA multifactor interactions and can serve as a reliable screening platform to uncover HC-dependent bio-nano interactions to enable the next-generation quality-by-design (QbD) nanomedicines for better clinical translation.

Effect of Surface Chemistry and Associated Protein Corona on the Long-Term Biodegradation of Iron Oxide Nanoparticles In Vivo

The protein corona formed on the surface of a nanoparticle in a biological medium determines its behavior in vivo. Herein, iron oxide nanoparticles containing the same core and shell, but bearing two different surface coatings, either glucose or poly(ethylene glycol), were evaluated. The nanoparticles' protein adsorption, in vitro degradation, and in vivo biodistribution and biotransformation over four months were investigated. Although both types of nanoparticles bound similar amounts of proteins in vitro, the differences in the protein corona composition correlated to the nanoparticles biodistribution in vivo. Interestingly, in vitro degradation studies demonstrated faster degradation for nanoparticles functionalized with glucose, whereas the in vivo results were opposite with accelerated biodegradation and clearance of the nanoparticles functionalized with poly(ethylene glycol). Therefore, the variation in the degradation rate observed in vivo could be related not only to the molecules attached to the surface, but also with the associated protein corona, as the key role of the adsorbed proteins on the magnetic core degradation has been demonstrated in vitro.