Machine learning to determine optimal conditions for controlling the size of elastin-based particles

AbstractThis paper evaluates the aggregation behavior of a potential drug and gene delivery system that combines branched polyethyleneimine (PEI), a positively-charged polyelectrolyte, and elastin-like polypeptide (ELP), a recombinant polymer that exhibits lower critical solution temperature (LCST). The LCST behavior of ELP has been extensively studied, but there are no quantitative ways to control the size of aggregates formed after the phase transition. The aggregate size cannot be maintained when the temperature is lowered below the LCST, unless the system exhibits hysteresis and forms irreversible aggregates. This study shows that conjugation of ELP with PEI preserves the aggregation behavior that occurs above the LCST and achieves precise aggregate radii when the solution conditions of pH (3, 7, 10), polymer concentration (0.1, 0.15, 0.3 mg/mL), and salt concentration (none, 0.2, 1 M) are carefully controlled. K-means cluster analyses showed that salt concentration was the most critical factor controlling the hydrodynamic radius and LCST. Conjugating ELP to PEI allowed crosslinking the aggregates and achieved stable particles that maintained their size below LCST, even after removal of the harsh (high salt or pH) conditions used to create them. Taken together, the ability to control aggregate sizes and use of crosslinking to maintain stability holds excellent potential for use in biological delivery systems.

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Bottlebrush polymers in the melt and polyelectrolytes in solution share common structural features

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1916362117 ◽

2020 ◽

Vol 117 (10) ◽

pp. 5168-5175 ◽

Cited By ~ 4

Author(s):

Joel M. Sarapas ◽

Tyler B. Martin ◽

Alexandros Chremos ◽

Jack F. Douglas ◽

Kathryn L. Beers

Keyword(s):

Neutron Scattering ◽

Correlation Length ◽

Salt Concentration ◽

Polymer Concentration ◽

Structural Features ◽

Peak Position ◽

Correlation Peak ◽

Grafting Density ◽

Scattering Measurements ◽

Polyelectrolyte Solutions

Uncharged bottlebrush polymer melts and highly charged polyelectrolytes in solution exhibit correlation peaks in scattering measurements and simulations. Given the striking superficial similarities of these scattering features, there may be a deeper structural interrelationship in these chemically different classes of materials. Correspondingly, we constructed a library of isotopically labeled bottlebrush molecules and measured the bottlebrush correlation peak position q*=2π/ξ by neutron scattering and in simulations. We find that the correlation length scales with the backbone concentration, ξ∼cBB−0.47, in striking accord with the scaling of ξ with polymer concentration cP in semidilute polyelectrolyte solutions (ξ∼cP−1/2). The bottlebrush correlation peak broadens with decreasing grafting density, similar to increasing salt concentration in polyelectrolyte solutions. ξ also scales with sidechain length to a power in the range of 0.35–0.44, suggesting that the sidechains are relatively collapsed in comparison to the bristlelike configurations often imagined for bottlebrush polymers.

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Dual-temperature and pH responsive (ethylene glycol)-based nanogels via structural design

Polymer Chemistry ◽

10.1039/c3py01772a ◽

2014 ◽

Vol 5 (8) ◽

pp. 3061-3070 ◽

Cited By ~ 22

Author(s):

Yohei Kotsuchibashi ◽

Ravin Narain

Keyword(s):

Carboxylic Acid ◽

Ethylene Glycol ◽

Salt Concentration ◽

Structural Design ◽

Solution Temperature ◽

Ph Responsive ◽

Solution Ph ◽

Critical Solution Temperature ◽

Carboxylic Acid Groups ◽

The Core

Dual-temperature and pH responsive (ethylene glycol)-based nanogels were synthesized. Both the core and the shell of the nanogels showed a lower critical solution temperature (LCST) and the LCST of the shell was strongly affected by the solution pH and salt concentration due to the presence of carboxylic acid groups at the nanogel surface.

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Aggregation of Gold Nanoparticles in Presence of the Thermoresponsive Cationic Diblock Copolymer PNIPAAM48-b-PAMPTMA6

Polymers ◽

10.3390/polym13234066 ◽

2021 ◽

Vol 13 (23) ◽

pp. 4066

Author(s):

David Herrera Robalino ◽

María del Mar Durán del Amor ◽

Carmen María Almagro Gómez ◽

José Ginés Hernández Cifre

Keyword(s):

Gold Nanoparticles ◽

High Ionic Strength ◽

Solution Temperature ◽

Trimethylammonium Chloride ◽

Aggregation Process ◽

Critical Solution Temperature ◽

Transmission Electron ◽

Vis Spectroscopy ◽

Copolymer Poly ◽

Positively Charged

The adsorption of the thermoresponsive positively charged copolymer poly(N-isopropylacrylamide)-block-poly(3-acrylamidopropyl)trimethylammonium chloride, PNIPAAM48-b-PAMPTMA6(+), onto negatively charged gold nanoparticles can provide stability to the nanoparticles and make the emerging structure tunable by temperature. In this work, we characterize the nanocomposite formed by gold nanoparticles and copolymer chains and study the influence of the copolymer on the expected aggregation process that undergoes those nanoparticles at high ionic strength. We also determine the lower critical solution temperature (LCST) of the copolymer (around 42 °C) and evaluate the influence of the temperature on the nanocomposite. For those purposes, we use dynamic light scattering, UV-vis spectroscopy and transmission electron microscopy. At the working PNIPAAM48-b-PAMPTMA6(+) concentration, we observe the existence of copolymer structures that trap the gold nanoparticles and avoid the formation of nanoparticles aggregates. Finally, we discuss how these structures can be useful in catalysis and nanoparticles recovery.

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Fluorescence Tumor-Imaging Using a Thermo-Responsive Molecule with an Emissive Aminoquinoline Derivative

Nanomaterials ◽

10.3390/nano8100782 ◽

2018 ◽

Vol 8 (10) ◽

pp. 782 ◽

Cited By ~ 2

Author(s):

Takeru Araki ◽

Yasufumi Fuchi ◽

Shuhei Murayama ◽

Ryoma Shiraishi ◽

Tokimi Oyama ◽

...

Keyword(s):

Cloud Point ◽

Intravenous Administration ◽

Tumor Tissue ◽

Tumor Imaging ◽

Fluorescence Probe ◽

Local Heat ◽

Solution Temperature ◽

Lcst Behavior

We synthesized (2,4-trifluoromethyl-7-N-bis(2,5,8,11-tetraoxatridecane-13-yl)-aminoquinoline) TFMAQ-diEg4, an emissive aminoquinoline derivative that incorporated two tetraethyleneglycol chains into an amino group. TFMAQ-diEg4 showed fluorescence and thermo-responsive properties accompanied by a lower critical solution temperature (LCST), due to the introduction of the oligoethylene glycol chain. This thermo-responsive LCST behavior occurred at the border of a cloud point. Below and above the cloud point, self-assemblies of 6-7-nm nanoparticles and ~2000-nm microparticles were observed, in vitro. In addition, TFMAQ-diEg4 showed a high solubility, over 20 mM for aqueous solution, in vivo, which not only prevented thrombosis but also allowed various examinations, such as single intravenous administration and intravenous drips. Intravenous administration of TFMAQ-diEg4, to tumor-bearing, mice led to the accumulation of the molecule in the tumor tissue, as observed by fluorescence imaging. A subset of mice was treated with local heat around their tumor tissue and an intravenous drip of TFMAQ-diEg4, which led to a high intensity of TFMAQ-diEg4 emission within the tumor tissue. Therefore, we revealed that TFMAQ-diEg4 was useful as a fluorescence probe with thermo-responsive properties.

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A Critical Factor for Quantifying Proteins in Unmodified Gold Nanoparticles-Based Aptasensing: The Effect of pH

Chemosensors ◽

10.3390/chemosensors8040098 ◽

2020 ◽

Vol 8 (4) ◽

pp. 98

Author(s):

Dai Lu ◽

Dong Zhang ◽

Qian Zhao ◽

Xiangyang Lu ◽

Xingbo Shi

Keyword(s):

Gold Nanoparticles ◽

Limit Of Detection ◽

Protein Detection ◽

Critical Factor ◽

Cost Effective ◽

Protein Corona ◽

Target Protein ◽

Universal Method ◽

Salt Addition ◽

Positively Charged

Unmodified gold nanoparticles (AuNPs)-based aptasensing (uGA) assay has been widely implemented in the determination of many different targets, but there are few reports on protein detection using uGA. Here, we designed a uGA assay for protein detection including the elimination of interfering proteins. Positively charged protein can be absorbed directly on the surface of AuNPs to form “protein corona”, which results in the aggregation of AuNPs even without salt addition, thereby preventing target protein detection. To overcome this problem, we systematically investigated the effect of modifying the pH of the solution during the uGA assay. A probe solution with a pH slightly higher than the isoelectric points (pI) of the target protein was optimal for protein detection in the uGA assay, allowing the aptamer to selectively detect the target protein. Three proteins (beta-lactoglobulin, lactoferrin, and lysozyme) with different pI were chosen as model proteins to validate our method. Positively charged interfering proteins (with pIs higher than the optimal pH) were removed by centrifugation of protein corona/AuNPs aggregates before the implementation of actual sample detection. Most importantly, the limit of detection (LOD) for all three model proteins was comparable to that of other methods, indicating the significance of modulating the pH. Moreover, choosing a suitable pH for a particular target protein was validated as a universal method, which is significant for developing a novel, simple, cost-effective uGA assay for protein detection.

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Upper Critical Solution Temperature (UCST) Behavior of Coacervate of Cationic Protamine and Multivalent Anions

Polymers ◽

10.3390/polym11040691 ◽

2019 ◽

Vol 11 (4) ◽

pp. 691 ◽

Cited By ~ 2

Author(s):

Hyungbin Kim ◽

Byoung-jin Jeon ◽

Sangsik Kim ◽

YongSeok Jho ◽

Dong Soo Hwang

Keyword(s):

Electrostatic Interactions ◽

Solution Temperature ◽

Complex Coacervation ◽

Critical Factors ◽

Critical Solution Temperature ◽

Temperature Changes ◽

Upper Critical Solution Temperature ◽

Large Asymmetry ◽

Positively Charged ◽

Liquid Liquid Phase Separation

Complex coacervation is an emerging liquid/liquid phase separation (LLPS) phenomenon that behaves as a membrane-less organelle in living cells. Yet while one of the critical factors for complex coacervation is temperature, little analysis and research has been devoted to the temperature effect on complex coacervation. Here, we performed a complex coacervation of cationic protamine and multivalent anions (citrate and tripolyphosphate (TPP)). Both mixtures (i.e., protamine/citrate and protamine/TPP) underwent coacervation in an aqueous solution, while a mixture of protamine and sodium chloride did not. Interestingly, the complex coacervation of protamine and multivalent anions showed upper critical solution temperature (UCST) behavior, and the coacervation of protamine and multivalent anions was reversible with solution temperature changes. The large asymmetry in molecular weight between positively charged protamine (~4 kDa) and the multivalent anions (<0.4 kDa) and strong electrostatic interactions between positively charged guanidine residues in protamine and multivalent anions were likely to contribute to UCST behavior in this coacervation system.

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Drag Reduction in Synthetic Seawater by Flexible and Rigid Polymer Addition Into a Rotating Cylindrical Double Gap Device

Journal of Fluids Engineering ◽

10.1115/1.4031229 ◽

2015 ◽

Vol 138 (2) ◽

Cited By ~ 17

Author(s):

Rafhael M. Andrade ◽

Anselmo S. Pereira ◽

Edson J. Soares

Keyword(s):

Drag Reduction ◽

Turbulent Flows ◽

Salt Concentration ◽

Polymer Concentration ◽

Transient Behavior ◽

Turbulent Structures ◽

Polymer Addition ◽

Rigid Polymer ◽

Potential Applications ◽

Poly Ethylene

Flexible and rigid long chain polymers in very dilute solutions can significantly reduce the drag in turbulent flows. The polymers successively stretch and coil by interacting with the turbulent structures, which changes the turbulent flow and further imposes a transient behavior on the drag reduction (DR) as well as a subsequent mechanical polymer degradation. This time-dependent phenomenon is strongly affected by a number of parameters, which are analyzed here, such as the Reynolds number, polymer concentration, polymer molecular weight, and salt concentration. This last parameter can dramatically modify the polymeric structure. The investigation of the salt concentration's impact on the DR is mostly motivated by some potential applications of this technique to ocean transport and saline fluid flows. In the present paper, a cylindrical double gap rheometer device is used to study the effects of salt concentration on DR over time. The reduction of drag is induced by three polymers: poly (ethylene oxide) (PEO), polyacrylamide (PAM), and xanthan gum (XG). These polymers are dissolved in deionized water both in the presence of salt and in its absence. The DR is displayed from the very start of the test to the time when the DR achieves its final level of efficiency, following the mechanical degradations. The presence of salt in PEO and XG solutions reduces the maximum DR, DRmax, as well as the time to achieve it. In contrast, the DR does not significantly change over the time for PAM solutions upon the addition of salt.

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Surface charges of anionic and cationic polyelectrolytes and their effects on the nucleation and the growth of CaCO3 crystals

e-Polymers ◽

10.1515/epoly.2009.9.1.1620 ◽

2009 ◽

Vol 9 (1) ◽

Author(s):

Amane Jada ◽

Arnaud Verraes ◽

Alexandrine Aue ◽

Céline Ducroquetz

Keyword(s):

Surface Charge ◽

Calcium Ions ◽

Polymer Concentration ◽

Free Calcium ◽

Precipitation Reaction ◽

Surface Charges ◽

Strong Reduction ◽

Interaction Efficiency ◽

Cationic Polyelectrolytes ◽

Positively Charged

AbstractStreaming Induced Potential (SIP) of polystyrene sulfonate, PSS, and poly(ethylenimine), PEI, in the presence of monovalent (NaCl) and divalent (CaCl2) electrolytes, were measured at ambient temperature. The data indicate that screening of polyelectrolyte surface charge, i.e. the reduction of SIP amplitude, is more efficient by divalent CaCl2, as compared to monovalent NaCl electrolytes. The screening of polyelectrolyte surface charge leads to reduction of the mutual repulsion between the polyelectrolyte segments. In the case of CaCl2 electrolyte, since PSS and PEI are, respectively, negatively and positively charged, sequestration of calcium ions by the polyelectrolyte leads to strong reduction of the free calcium ions concentration in the medium in the presence of the PSS when compared to the PEI. Further, the preparation of CaCO3 particles through a precipitation reaction, at room temperature, by using PSS and PEI polyelectrolytes as crystal modifiers were investigated. The final CaCO3 particles are found to result from the aggregation of nanocrystals, and have various shapes and sizes depending on polymer concentration and structure. It comes out that the properties of CaCO3 particles prepared in the presence of the polymer are function of the interaction efficiency between the polymer-repeating units and the calcium ions. Such interaction is found to affect the free calcium ions concentration in the medium.

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Synthesis and Lcst Behavior of Thermally Responsive Poly(N-Isopropylacrylamide)/Layered Silicate Nanocomposites

MRS Proceedings ◽

10.1557/proc-457-507 ◽

1996 ◽

Vol 457 ◽

Cited By ~ 12

Author(s):

Phillip B. Messersmith ◽

F. Znidarsich

Keyword(s):

Aqueous Suspension ◽

Layered Silicate ◽

Polymer Nanocomposite ◽

Solution Temperature ◽

Stimuli Responsive ◽

Thermally Responsive ◽

Isopropyl Acrylamide ◽

Lcst Behavior ◽

Hydrogel Composites

ABSTRACTStimuli responsive polymeric hydrogel composites were synthesized by room temperature copolymerization of N-isopropyl acrylamide and methylene bisacrylamide (crosslinking monomer) in an aqueous suspension of Na-montmorillonite. Hydrogels containing 3.5 weight % of montmorillonite exhibited a lower critical solution temperature (LCST) similar to unmodified PNIPAM hydrogel (approximately 32°C), and underwent a reversible 60–70% volume shrinkage when heated from ambient temperature to above the LCST. However, hydrogels containing 10 weight% montmorillonite did not exhibit a measurable LCST, and underwent considerably less shrinkage when heated. A solvent exchange reaction was used to replace the water with an acrylic monomer, which was polymerized in-situ to create a delaminated montmorillonite/polymer nanocomposite.

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