ABSTRACT
We have recently proposed preferential binding by a cosolvent as the mechanism for chain collapse under co-non-solvency. Here we summarise our earlier works and provide further evidence that alcohol preferentially binds to PNIPAm, forming cosolvent bridges, and thus drives the transition. We also clarify some of the common misconceptions evoked in this debate with Pica and Graziano (PG), reinforcing the arguments of our earlier reply-comment [Soft Matter, 2017, 13, 2292] and published works.
Subject(s)
Methanol/chemistry , Water/chemistry , Ethanol , Molecular Conformation , Solvents/chemistryABSTRACT
Tumor necrosis factor-alpha (TNF-α) is a pleiotropic immune stimulatory cytokine and natural endotoxin that can induce necrosis and regression in solid tumors. However, systemic administration of TNF-α is not feasible due to its short half-life and acute toxicity, preventing its widespread use in cancer treatment. Dendritic mesoporous silica nanoparticles (DMSN) are used coated with a pH-responsive block copolymer gate system combining charged hyperbranched polyethylenimine and nonionic hydrophilic polyethylenglycol to encapsulate TNF-α and deliver it into various cancer cell lines and dendritic cells. Half-maximal effective concentration (EC50 ) for loaded TNF-α is reduced by more than two orders of magnitude. Particle stability and premature cargo release are assessed with enzyme-linked immunosorbent assay. TNF-α-loaded particles are stable for up to 5 d in medium. Tumor cells are grown in vitro as 3D fluorescent ubiquitination-based cell cycle indicator spheroids that mimic in vivo tumor architecture and microenvironment, allowing real-time cell cycle imaging. DMSN penetrate these spheroids, release TNF-α from its pores, preferentially affect cells in S/G2/M phase, and induce cell death in a time- and dose-dependent manner. In conclusion, DMSN encapsulation is demonstrated, which is a promising approach to enhance delivery and efficacy of antitumor drugs, while minimizing adverse side effects.
Subject(s)
Cell Cycle/drug effects , Drug Delivery Systems/methods , Nanoparticles , Neoplasms/drug therapy , Silicon Dioxide , Tumor Necrosis Factor-alpha , Cell Line, Tumor , Dose-Response Relationship, Drug , Humans , Nanoparticles/chemistry , Nanoparticles/therapeutic use , Neoplasms/metabolism , Porosity , Silicon Dioxide/chemistry , Silicon Dioxide/pharmacokinetics , Silicon Dioxide/pharmacology , Tumor Necrosis Factor-alpha/chemistry , Tumor Necrosis Factor-alpha/pharmacokinetics , Tumor Necrosis Factor-alpha/pharmacologyABSTRACT
In a comment van der Vegt and Rodriguez-Ropero (vdVRR) challenged our explanation of the co-non-solvency effect of PNIPAm in aqueous methanol solutions. They argue, based on a careful selection of published studies including some of their own, that direct repulsions between the different constituents are sufficient to understand this phenomenon. According to vdVRR, the emerging view of entropic collapse, put forward by Flory (1910-1985) to explain common polymers in poor solvents, would be enough to explain co-non-solvency. In this reply we attempt to bring this discussion into firmer grounds. We provide a more comprehensive view of available experimental, numerical and theoretical results and review basic concepts of physical chemistry and of statistical mechanics of polymer collapse that show how methanol mediated attractions between chain monomers are required to understand this fascinating behavior.
Subject(s)
Methanol/chemistry , Water/chemistry , Molecular Conformation , Polymers/chemistry , Solvents/chemistryABSTRACT
We synthesized a novel green-light-responsive tetra-ortho-isopropoxy-substituted azobenzene (ipAzo). Cis-ipAzo forms a strong host-guest complex with γ-cyclo dextrin (γ-CD) whereas trans-ipAzo binds weakly. This new photoresponsive host-guest interaction is reverse to the well-known azobenzene (Azo)/α-cyclodextrin (α-CD) complex, which is strong only between trans-Azo and α-CD. By combining the UV-light-responsive Azo/α-CD and green-light-responsive ipAzo/γ-CD host-guest complexes, a photoresponsive orthogonal supramolecular system is developed.
ABSTRACT
Surfactants, even in miniscule amounts, are often used for the synthesis and especially the stabilization of nanomaterials, which is essential for in vivo applications. In this study, we show that the interaction between nanoparticles and proteins strongly depends on the type of stabilizing surfactants and their (small) concentration changes. The reaction between human serum albumin and polystyrene nanoparticles stabilized by an ionic or nonionic surfactant-sodium dodecyl sulfate or Lutensol AT50, respectively-was monitored using isothermal titration calorimetry. It was found that the amount of surfactant molecules on the surface significantly determines the protein binding affinity and adsorption stoichiometry, which is important for all nanomaterials coming into contact with biological components such as blood plasma proteins. Thus after synthesizing nanomaterials for in vivo applications as drug delivery agents, it is crucial to perform a detailed analysis of the obtained surface chemistry that accounts for the presence of minimal amounts of stabilizing agents.
Subject(s)
Drug Delivery Systems , Nanoparticles/chemistry , Serum Albumin/chemistry , Surface-Active Agents/chemistry , Adsorption , Calorimetry , Humans , Nanoparticles/therapeutic use , Particle Size , Polystyrenes/chemistry , Polystyrenes/therapeutic use , Protein Binding , Serum Albumin/therapeutic use , Sodium Dodecyl Sulfate/chemistry , Sodium Dodecyl Sulfate/therapeutic use , Surface-Active Agents/therapeutic useABSTRACT
Combining nuclear magnetic resonance (NMR), dynamic light scattering (DLS), and µs long all-atom simulations with two million particles, we establish a delicate correlation between increased side chain organization of PNIPAm and its collapse in aqueous methanol mixtures. We find that the preferential binding of methanol with PNIPAm side chains, bridging distal monomers along the polymer backbone, results in increased organization. Furthermore, methanol-PNIPAm preferential binding is dominated by hydrogen bonding. Our findings reveal that the collapse of PNIPAm is dominated by enthalpic interactions and that the standard poor solvent (entropic) effects play no major role.
ABSTRACT
Fluorescently labelled proteins are often used to study processes in vitro, e.g. the binding of proteins to cell surfaces or the adsorption of plasma proteins on drug nanocarriers. However, the fact that the fluorescent labelling may affect the protein properties is frequently neglected. On the example of a simple model system, we reiterate the importance of this issue by showing that even a single label may perturb interactions between hydrophilic starch-based nanocapsules and serum albumin and thus prevent binding.
Subject(s)
Fluorescent Dyes/chemistry , Nanostructures/chemistry , Polymers/chemistry , Serum Albumin/chemistry , Adsorption , Animals , Cattle , Fluorescence , Humans , Hydrophobic and Hydrophilic Interactions , Surface PropertiesABSTRACT
The current gold standard to reduce non-specific cellular uptake of drug delivery vehicles is by covalent attachment of poly(ethylene glycol) (PEG). It is thought that PEG can reduce protein adsorption and thereby confer a stealth effect. Here, we show that polystyrene nanocarriers that have been modified with PEG or poly(ethyl ethylene phosphate) (PEEP) and exposed to plasma proteins exhibit a low cellular uptake, whereas those not exposed to plasma proteins show high non-specific uptake. Mass spectrometric analysis revealed that exposed nanocarriers formed a protein corona that contains an abundance of clusterin proteins (also known as apolipoprotein J). When the polymer-modified nanocarriers were incubated with clusterin, non-specific cellular uptake could be reduced. Our results show that in addition to reducing protein adsorption, PEG, and now PEEPs, can affect the composition of the protein corona that forms around nanocarriers, and the presence of distinct proteins is necessary to prevent non-specific cellular uptake.
Subject(s)
Blood Proteins/chemistry , Blood Proteins/metabolism , Drug Carriers/chemistry , Nanoparticles/chemistry , Polyesters/chemistry , Polyethylene Glycols/chemistry , Adsorption , Clusterin , HumansABSTRACT
Whenever nanoparticles encounter biological fluids like blood, proteins adsorb on their surface and form a so-called protein corona. Although its importance is widely accepted, information on the influence of surface functionalization of nanocarriers on the protein corona is still sparse, especially concerning how the functionalization of PEGylated nanocarriers with targeting agents will affect protein corona formation and how the protein corona may in turn influence the targeting effect. Herein, hydroxyethyl starch nanocarriers (HES-NCs) were prepared, PEGylated, and modified on the outer PEG layer with mannose to target dendritic cells (DCs). Their interaction with human plasma was then studied. Low overall protein adsorption with a distinct protein pattern and high specific affinity for DC binding were observed, thus indicating an efficient combination of "stealth" and targeting behavior.
Subject(s)
Dendritic Cells/metabolism , Drug Carriers/metabolism , Mannose/metabolism , Nanoparticles/metabolism , Protein Corona/metabolism , Drug Carriers/chemistry , Drug Delivery Systems , Humans , Hydroxyethyl Starch Derivatives/chemistry , Hydroxyethyl Starch Derivatives/metabolism , Mannose/chemistry , Nanoparticles/chemistry , Polyethylene Glycols/chemistry , Polyethylene Glycols/metabolismABSTRACT
Herein, the synthesis and characterization of heparin-based nanocapsules (NCs) as potential drug delivery systems is described. For the synthesis of the heparin-based NCs, the versatile method of miniemulsion polymerization at the droplets interface was achieved resulting in narrowly distributed NCs with 180 nm in diameter. Scanning and transmission electron microscopy images showed clearly NC morphology. A highly negative charge density for the heparin-based NCs was determined by measuring the electro-kinetic potential. Measuring the activated clotting time demonstrated the biological intactness of the polymeric shell. The ability of heparin-based NCs to bind to antithrombin (AT III) was investigated using isothermal titration calorimetry and dynamic light scattering experiments. The chemical stability of the NCs was studied in physiological protein-containing solutions and also in medically interesting fluids such as sodium chloride 0.9%, Ringer's solution, and phosphate buffer saline using dynamic light scattering and measuring the fluorescence intensity. The impressive uptake of NCs in different cells was confirmed by fluorescence-activated cell sorting, confocal laser scanning microscopy, and transmission electron microscopy. The low toxicity of all types of NCs was demonstrated.
Subject(s)
Antithrombin III , Heparin , Nanocapsules/chemistry , Antithrombin III/chemistry , Antithrombin III/pharmacokinetics , Antithrombin III/pharmacology , HeLa Cells , Heparin/chemistry , Heparin/pharmacokinetics , Heparin/pharmacology , Humans , MCF-7 Cells , Nanocapsules/ultrastructureABSTRACT
Highly reactive emulsions were stabilized by employing a surfmer analogous concept. An interfacial reaction between an emulsion droplet and a cross-linkable reactive surfactant was used to provide colloidal stability and simultaneously maintain the majority of the reactive groups. Polyaddition-type reaction between epoxy and amine was chosen as a model system to spontaneously and covalently bond the surfactant to the emulsion droplets. The interfacial reaction was monitored via isothermal titration calorimetry analysis. With this method, the increased colloidal stability could be attributed to a reaction rather than a pure physical adsorption. The maintained reactivity of the emulsion droplets enables consecutive conversions with coreactive components, e.g., for cross-linking reactions, corrosion protection, or functional coatings.
