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Journal of Computer-aided Molecular... Dec 2023Theoretical predictions of the solubilizing capacity of micelles and vesicles present in intestinal fluid are important for the development of new delivery techniques...
Theoretical predictions of the solubilizing capacity of micelles and vesicles present in intestinal fluid are important for the development of new delivery techniques and bioavailability improvement. A balance between accuracy and computational cost is a key factor for an extensive study of numerous compounds in diverse environments. In this study, we aimed to determine an optimal molecular dynamics (MD) protocol to evaluate small-molecule interactions with micelles composed of bile salts and phospholipids. MD simulations were used to produce free energy profiles for three drug molecules (danazol, probucol, and prednisolone) and one surfactant molecule (sodium caprate) as a function of the distance from the colloid center of mass. To address the challenges associated with such tasks, we compared different simulation setups, including freely assembled colloids versus pre-organized spherical micelles, full free energy profiles versus only a few points of interest, and a coarse-grained model versus an all-atom model. Our findings demonstrate that combining these techniques is advantageous for achieving optimal performance and accuracy when evaluating the solubilization capacity of micelles. All-atom (AA) and coarse-grained (CG) umbrella sampling (US) simulations and point-wise free energy (FE) calculations were compared to their efficiency to computationally analyze the solubilization of active pharmaceutical ingredients in intestinal fluid colloids.
Topics: Micelles; Molecular Dynamics Simulation; Colloids; Surface-Active Agents
PubMed: 38103089
DOI: 10.1007/s10822-023-00541-1 -
Journal of Dairy Science Dec 2021Our objective was to determine the effects of temperature and protein concentration on viscosity increase and gelation of liquid micellar casein concentrate (MCC) at...
Our objective was to determine the effects of temperature and protein concentration on viscosity increase and gelation of liquid micellar casein concentrate (MCC) at protein concentrations from 6 to 20% during refrigerated storage. Skim milk (∼350 kg) was pasteurized (72°C for 16 s) and filtered through a ceramic microfiltration system to make MCC and replicated 3 times. The liquid MCC was immediately concentrated via a plate ultrafiltration system to 18% protein (wt/wt). The MCC was then diluted to various protein concentrations (6-18%, wt/wt). The highest protein concentrations of MCC formed gels almost immediately on cooling to 4°C, whereas lower concentrations of MCC were viscous liquids. Apparent viscosity (AV) determination using a rotational viscometer, gel strength using a compression test, and protein analysis of supernatants from ultracentrifugation by the Kjeldahl method were performed. The AV data were collected from MCC (6.54, 8.75, 10.66, and 13.21% protein) at 4, 20, and 37°C, and compression force test data were collected for MCC (15.6, 17.9, and 20.3% protein) over a period of 2-wk storage at 4°C. The maximum compressive load was compared at each time point to determine the changes in gel strength over time. Supernatants from MCC of 6.96 and 11.61% protein were collected after ultracentrifugation (100,605 × g for 2 h at 4, 20, and 37°C) and the nitrogen distributions (total, noncasein, casein, and nonprotein nitrogen) were determined. The protein and casein as a percent of true protein concentration in the liquid phase around casein micelles in MCC increased with increasing total MCC protein concentration and with decreasing temperature. Casein as a percent of true protein at 4°C in the liquid phase around casein micelles increased from about 16% for skim milk to about 78% for an MCC containing 11.6% protein. This increase was larger than expected, and this may promote increased viscosity. The AV of MCC solutions in the range of 6 to 13% casein increased with increasing casein concentration and decreasing temperature. We observed a temperature by protein concentration interaction, with AV increasing more rapidly with decreasing temperature at high protein concentration. The increase in AV with decreasing temperature may be due to the increase in protein concentration in the aqueous phase around the casein micelles. The MCC containing about 16 and 18% casein gelled upon cooling to form a gel that was likely a particle jamming gel. These gels increased in strength over 10 d of storage at 4°C, likely due either to the migration of casein (CN) out of the micelles and interaction of the nonmicellar CN to form a network that further strengthened the random loose jamming gel structure or to a gradual increase in voluminosity of the casein micelles during storage at 4°C.
Topics: Animals; Caseins; Gels; Micelles; Milk; Viscosity
PubMed: 34531054
DOI: 10.3168/jds.2021-20658 -
The Journal of Physical Chemistry. B Jul 2021Polyelectrolyte complex micelles (PCMs) are a unique class of self-assembled nanoparticles that form with a core of associated polycations and polyanions,...
Polyelectrolyte complex micelles (PCMs) are a unique class of self-assembled nanoparticles that form with a core of associated polycations and polyanions, microphase-separated from neutral, hydrophilic coronas in aqueous solution. The hydrated nature and structural and chemical versatility make PCMs an attractive system for delivery and for fundamental polymer physics research. By leveraging block copolymer design with controlled self-assembly, fundamental structure-property relationships can be established to tune the size, morphology, and stability of PCMs precisely in pursuit of tailored nanocarriers, ultimately offering storage, protection, transport, and delivery of active ingredients. This perspective highlights recent advances in predictive PCM design, focusing on (i) structure-property relationships to target specific nanoscale dimensions and shapes and (ii) characterization of PCM dynamics primarily using time-resolved scattering techniques. We present several vignettes from these two emerging areas of PCM research and discuss key opportunities for PCM design to advance precision medicine.
Topics: Hydrophobic and Hydrophilic Interactions; Micelles; Nanoparticles; Polyelectrolytes
PubMed: 34160221
DOI: 10.1021/acs.jpcb.1c01258 -
Biophysical Journal Jul 2023The resolution revolution has increasingly enabled single-particle cryogenic electron microscopy (cryo-EM) reconstructions of previously inaccessible systems, including...
The resolution revolution has increasingly enabled single-particle cryogenic electron microscopy (cryo-EM) reconstructions of previously inaccessible systems, including membrane proteins-a category that constitutes a disproportionate share of drug targets. We present a protocol for using density-guided molecular dynamics simulations to automatically refine atomistic models into membrane protein cryo-EM maps. Using adaptive force density-guided simulations as implemented in the GROMACS molecular dynamics package, we show how automated model refinement of a membrane protein is achieved without the need to manually tune the fitting force ad hoc. We also present selection criteria to choose the best-fit model that balances stereochemistry and goodness of fit. The proposed protocol was used to refine models into a new cryo-EM density of the membrane protein maltoporin, either in a lipid bilayer or detergent micelle, and we found that results do not substantially differ from fitting in solution. Fitted structures satisfied classical model-quality metrics and improved the quality and the model-to-map correlation of the x-ray starting structure. Additionally, the density-guided fitting in combination with generalized orientation-dependent all-atom potential was used to correct the pixel-size estimation of the experimental cryo-EM density map. This work demonstrates the applicability of a straightforward automated approach to fitting membrane protein cryo-EM densities. Such computational approaches promise to facilitate rapid refinement of proteins under different conditions or with various ligands present, including targets in the highly relevant superfamily of membrane proteins.
Topics: Cryoelectron Microscopy; Molecular Dynamics Simulation; Micelles; Protein Conformation
PubMed: 37277992
DOI: 10.1016/j.bpj.2023.05.033 -
Journal of the Royal Society, Interface Oct 2022We model the environment of eukaryotic nuclei by representing macromolecules by only their entropic properties, with globular molecules represented by spherical colloids...
We model the environment of eukaryotic nuclei by representing macromolecules by only their entropic properties, with globular molecules represented by spherical colloids and flexible molecules by polymers. We put particular focus on proteins with both globular and intrinsically disordered regions, which we represent with 'tadpole' constructed by grafting single polymers and colloids together. In Monte Carlo simulations, we find these tadpoles support phase separation via depletion flocculation, and demonstrate several surfactant behaviours, including being found preferentially at interfaces and forming micelles in single phase solution. Furthermore, the model parameters can be tuned to give a tadpole a preference for either bulk phase. However, we find entropy too weak to drive these behaviours by itself at likely biological concentrations.
Topics: Animals; Colloids; Larva; Micelles; Polymers; Proteins; Surface-Active Agents
PubMed: 36195115
DOI: 10.1098/rsif.2022.0172 -
Journal of Controlled Release :... Oct 2021mRNA-based therapy has been evaluated in preclinical and clinical studies for the treatment of a wide variety of disease such as cancer immunotherapies and infectious...
mRNA-based therapy has been evaluated in preclinical and clinical studies for the treatment of a wide variety of disease such as cancer immunotherapies and infectious disease vaccines. However, it remains challenging to development safe and efficient delivery system. Here, we have designed a novel self-assembled polymeric micelle based on vitamin E succinate modified polyethyleneimine copolymer (PVES) to delivery mRNA. In vitro, PVES could transfect mRNA into multiple cell lines such as HEK-293T, HeLa and Vero and the transfection efficiencies were much higher than PEI 25 k. In addition, the cytotoxicity of PVES was much lower than PEI 25 k. Furthermore, mice administered intramuscularly with PVES/SARS-CoV-2 mRNA vaccine induced potent antibody response and show no obvious toxicity. These results demonstrated the potential of PVES as a safe and effective delivery carrier for mRNA.
Topics: Animals; COVID-19; COVID-19 Vaccines; HeLa Cells; Humans; Mice; Micelles; Polyethyleneimine; RNA, Messenger; SARS-CoV-2; Transfection
PubMed: 34481924
DOI: 10.1016/j.jconrel.2021.08.061 -
Langmuir : the ACS Journal of Surfaces... Feb 2021Two new surfactants, FOM and FDM, were designed as partially fluorinated analogues of -dodecyl-β-D-maltoside (DDM). The micellization properties and the morphologies of...
Two new surfactants, FOM and FDM, were designed as partially fluorinated analogues of -dodecyl-β-D-maltoside (DDM). The micellization properties and the morphologies of the aggregates formed by the two surfactants in water and phosphate buffer were evaluated by NMR spectroscopy, surface tension measurement, isothermal titration calorimetry, dynamic light scattering, small-angle X-ray scattering, and analytical ultracentrifugation. As expected, the critical micellar concentration (cmc) was found to decrease with chain length of the fluorinated tail from 2.1-2.5 mM for FOM to 0.3-0.5 mM for FDM, and micellization was mainly entropy-driven at 25 °C. Close to their respective cmc, the micelle sizes were similar for both surfactants, that is, 7 and 13 nm for FOM and FDM, respectively, and both increased with concentration forming 4 nm diameter rods with maximum dimensions of 50 and 70 nm, respectively, at a surfactant concentration of ∼30 mM. The surfactants were found to readily solubilize lipid vesicles and extract membrane proteins directly from membranes. They were found more efficient than the commercial fluorinated detergent FHOM over a broad range of concentrations (1-10 mM) and even better than DDM at low concentrations (1-5 mM). When transferred into the two new surfactants, the thermal stability of the proteins bacteriorhodopsin (bR) and FhuA was higher than in the presence of their solubilization detergents and similar to that in DDM; furthermore, bR was stable over several months. The membrane enzymes SpNOX and BmrA were not as active as in DDM micelles but similarly active as in FOM. Together, these findings indicate both extracting and stabilizing properties of the new maltose-based fluorinated surfactants, making them promising tools in MP applications.
Topics: Maltose; Membrane Proteins; Micelles; Surface Tension; Surface-Active Agents
PubMed: 33539092
DOI: 10.1021/acs.langmuir.0c03214 -
Nature Nanotechnology Feb 2021Real-world bioelectronics applications, including drug delivery systems, biosensing and electrical modulation of tissues and organs, largely require biointerfaces at the...
Real-world bioelectronics applications, including drug delivery systems, biosensing and electrical modulation of tissues and organs, largely require biointerfaces at the macroscopic level. However, traditional macroscale bioelectronic electrodes usually exhibit invasive or power-inefficient architectures, inability to form uniform and subcellular interfaces, or faradaic reactions at electrode surfaces. Here, we develop a micelle-enabled self-assembly approach for a binder-free and carbon-based monolithic device, aimed at large-scale bioelectronic interfaces. The device incorporates a multi-scale porous material architecture, an interdigitated microelectrode layout and a supercapacitor-like performance. In cell training processes, we use the device to modulate the contraction rate of primary cardiomyocytes at the subcellular level to target frequency in vitro. We also achieve capacitive control of the electrophysiology in isolated hearts, retinal tissues and sciatic nerves, as well as bioelectronic cardiac sensing. Our results support the exploration of device platforms already used in energy research to identify new opportunities in bioelectronics.
Topics: Biocompatible Materials; Biosensing Techniques; Carbon; Electrodes; Equipment Design; Membranes, Artificial; Micelles; Nanostructures; Porosity
PubMed: 33288948
DOI: 10.1038/s41565-020-00805-z -
Biophysical Journal Apr 2020Laurdan fluorescence, novel spectral fitting, and dynamic light scattering were combined to determine lateral lipid organization in mixed lipid membranes of the oxidized...
Laurdan fluorescence, novel spectral fitting, and dynamic light scattering were combined to determine lateral lipid organization in mixed lipid membranes of the oxidized lipid, 1-palmitoyl-2-glutaryl-sn-glycero-3-phosphocholine (PGPC), and each of the three bilayer lipids, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), and 1-palmitoyl-2-oleoylphosphatidylcholine (POPC). Second harmonic spectra were computed to determine the number of elementary emissions present. All mixtures indicated two emissions. Accordingly, spectra were fit to two log-normal distributions. Changes with PGPC mole fraction, X, of the area of the shorter wavelength line and of dynamic light scattering-derived aggregate sizes show that: DPPC and PGPC form component-separated mixed vesicles for X ≤ 0.2 and coexisting vesicles and micelles for X > 0.2 in gel and liquid-ordered phases and for all X in the liquid-disordered phase; POPC and PGPC form randomly mixed vesicles for X ≤ 0.2 and component-separated mixed vesicles for X > 0.2. DOPC and PGPC separate into vesicles and micelles. Component segregation is due to unstable inhomogeneous membrane curvature stemming from lipid-specific intrinsic curvature differences between mixing molecules. PGPC is inverse cone-shaped because its truncated tail with a terminal polar group points into the interface. It is similar to and mixes with POPC, also an inverse cone because of mobility of its unsaturated tail. PGPC is least similar to DOPC because mobilities of both unsaturated tails confer a cone shape to DOPC, and PGPC separates form DOPC. DPPC and PGPC do not mix in the liquid-disordered phase because mobility of both tails in this phase renders DPPC a cone. DPPC is a cylinder in the gel phase and of moderate similarity to PGPC and mixes moderately with PGPC.
Topics: Glycerylphosphorylcholine; Lipid Bilayers; Micelles; Phosphatidylcholines
PubMed: 32246900
DOI: 10.1016/j.bpj.2020.03.009 -
Advanced Healthcare Materials May 2022Peptide-based cancer vaccines offer production and safety advantages but have had limited clinical success due to their intrinsic instability, rapid clearance, and low...
Peptide-based cancer vaccines offer production and safety advantages but have had limited clinical success due to their intrinsic instability, rapid clearance, and low cellular uptake. Nanoparticle-based delivery vehicles can improve the in vivo stability and cellular uptake of peptide antigens. Here, a well-defined, self-assembling mannosylated polymer is developed for anticancer peptide antigen delivery. The amphiphilic polymer is prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization, and the peptide antigens are conjugated to the pH-sensitive hydrophobic block through the reversible disulfide linkage for selective release after cell entry. The polymer-peptide conjugates self-assemble into sub-100 nm micelles at physiological pH and dissociate at endosomal pH. The mannosylated micellar corona increases the accumulation of vaccine cargoes in the draining inguinal lymph nodes and facilitates nanoparticle uptake by professional antigen presenting cells. In vivo studies demonstrate that the mannosylated micelle formulation improves dendritic cell activation and enhances antigen-specific T cell responses, resulting in higher antitumor immunity in tumor-bearing mice compared to free peptide antigen. The mannosylated polymer is therefore a simple and promising platform for the delivery of peptide cancer vaccines.
Topics: Animals; Antigens; Cancer Vaccines; Drug Delivery Systems; Mice; Micelles; Neoplasms; Peptides; Polymers; Vaccines, Subunit
PubMed: 34706166
DOI: 10.1002/adhm.202101651