Complex three-dimensional (3D) pore geometries, useful for tissue engineering scaffolds, can be fabricated via photo-crosslinking of resorbable poly(propylene fumarate) (PPF) resins using ...stereolithography (SLA) and/or continuous digital light processing (cDLP) methods. Physico-chemical parameters inherent to 3D printable resin design, include viscosity, polymer concentration, degree of polymerization, and resin printing temperature. We report here on our study of these parameters and their influence the cDLP 3D printing process and the resulting mechanical properties. A series of PPF oligomers were synthesized by the ring-opening copolymerization (ROCOP) of maleic anhydride and propylene oxide followed by a base-catalyzed isomerization. The resin viscosities were measured as a function of number-average molecular mass ( M n ̅ ) of the PPF oligomers (1.1, 1.7 and 2.0 kDa), concentrations of PPF in the reactive diluent diethyl fumarate (DEF) (50 and 75 wt %) and resin temperature (25 to 55 °C). The zero-shear viscosity (η0) of the resins was found to be temperature-dependent and follow a linear Arrhenius relationship. Tensile tests demonstrated mechanical properties within the range of trabecular bone, with the ultimate strength at break above 15 MPa and elastic moduli between 178 and 199 MPa.
3D/4D printing is enabling transformative advances in device manufacturing and medicine but remains limited by the lack of printable resorbable materials with advanced properties and functions. ...Herein, we report the rapid and precise 4D printing of shape-memory scaffolds based on poly(propylene fumarate) (PPF) star polymers. Scaffolds with tunable and distinguishable properties can be produced with identical polymer formulation and stoichiometry. The resulting scaffold glass transition temperatures and Young’s moduli increase with the postcuring time. Significantly, both the extent and rate of shape recovery following compression can be tuned by varying the strut design, the postcuring step duration, and/or the temperature applied for the recovery step. Finally, accelerated degradation studies confirmed the resorbability of the PPF star polymer gyroid scaffolds.
Compartmentalization and binding‐triggered conformational change regulate many metabolic processes in living matter. Here, we have synergistically combined these two biorelevant processes to tune the ...Diels‐Alder (DA) reactivity of a synthetic self‐complexing host‐guest molecular switch CBPQT4+‐Fu, consisting of an electron‐rich furan unit covalently attached to the electron‐deficient cyclobis(paraquat‐p‐phenylene) tetrachloride (CBPQT4+, 4Cl−) host. This design allows CBPQT4+‐Fu to efficiently compartmentalize the furan ring inside its host cavity in water, thereby protecting it from the DA reaction with maleimide. Remarkably, the self‐complexed CBPQT4+‐Fu can undergo a conformational change through intramolecular decomplexation upon the addition of a stronger binding molecular naphthalene derivative as a competitive guest, triggering the DA reaction upon addition of a chemical regulator. Remarkably, connecting the guest to a thermoresponsive lower critical solution temperature (LCST) copolymer regulator controls the DA reaction on command upon heating and cooling the reaction media beyond and below the cloud point temperature of the copolymer, representing a rare example of decreased reactivity upon increasing temperature. Altogether, this work opens up new avenues towards combined topological and supramolecular control over reactivity in synthetic constructs, enabling control over reactivity through molecular regulators or even mild temperature variations.
Combining two biorelevant concepts, i. e., compartmentalization and regulator‐induced conformational change allows control of the Diels‐Alder reactivity between a furan moiety and maleimide in water. Using a thermosensitive regulator enables the Diels‐Alder reaction to be turned off at elevated temperature, whereas it is activated by lowering the temperature, representing a rare example of reduced reactivity at elevated temperature.
Two pairs of oppositely charged PEO‐b‐poly(amino acid) copolymers with neutral poly(ethylene oxide) block and polypeptide block composed of the hydrophobic l‐phenylalanine (Phe) amino acid mixed with ...either negative l‐glutamic acid (Glu) or positive l‐lysine (Lys) units are synthesized. N‐carboxyanhydride (NCA) ring opening polymerization is performed with either PEO46‐NH2 or PEO114‐NH2 macroinitiators, leading respectively to PEO46‐b‐P(Glu100‐co‐Phe65) and PEO46‐b‐P(Lys100‐co‐Phe65), and PEO114‐b‐P(Glu60‐co‐Phe40) and PEO114‐b‐P(Lys60‐co‐Phe40). Polyion complexes (PIC) formed at near charge equilibrium led to vesicle formation (PICsomes), as shown by DLS, zetametry, and TEM. The good stability of PICsomes, even in high salinity media, is interpreted by ππ stacking hydrophobic interactions between the Phe residues, playing the role of “physical cross‐linking”. These PICsomes are successfully loaded with small interfering ribonucleic acid (siRNA) directed against firefly luciferase enzyme expression. They also exhibit minimal cell cytotoxicity while superior silencing efficacy is shown by cell bioluminescence assay as compared to free siRNA and a standard lipofectamine‐siRNA complex. As such, self‐assembly of oppositely charged PEO‐b‐poly(amino acids) block copolymers enables forming PICsomes of high stability thanks to ππ interactions of the Phe co‐monomer in the polypeptide block, with high potential as biocompatible nanocarriers for RNA interference.
A series of pH‐sensitive PEO‐b‐poly(l‐Glux‐co‐l‐Phey) and PEO‐b‐poly(l‐Lysx‐co‐l‐Phey) PEO‐copolypeptides are synthesized. The hydrophobic l‐Phe co‐monomer influences secondary structure and shifts effective pKa. Co‐assembly of oppositely charged PEO‐copolypeptides with similar amino acid content forms PICsomes stable in isotonic NaCl thanks to ππ stacking of l‐Phe. Duplex‐firefly siRNA encapsulation shows superior and less toxic luciferase gene silencing in HeLa cells than lipofectamine polyplex.
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•Sur-saturated Curcumin/PVP amorphous solid dispersions (ASD) obtained by milling.•PVP low dispersity drastically increases glass transition temperature of ASD with Curcumin.•Shortest ...PVP chains reduce the anti-plasticisation effect of Curcumin-PVP interactions.•Solubility of Curcumin is increased in ASD formulated with well-defined PVP.
Amorphous solid dispersions (ASD) are known to enhance the absorption of poorly water-soluble drugs. In this work we synthesise well-defined Polyvinylpyrrolidone (PVP) to establish the impact of dispersity and chain-end functionality on the physical properties of Curcumin (CUR)/PVP ASD. Thermodynamic characterisation of synthesised PVP emphasises a strong effect of the dispersity on the glass transition temperature (Tg), 50 °C higher for synthesised PVP than for commercial PVP K12 of same molar mass. This increase of Tg affects the thermodynamic properties of CUR/PVP ASD successfully formulated up to 70 wt% of CUR by milling or solvent evaporation. The evolution of both the Tg and CUR solubility values versus CUR content points out the development of fairly strong CUR-PVP interactions that strengthen the antiplasticising effect of PVP on the Tg of ASD. However, for ASD formulated with commercial PVP this effect is counterbalanced at low CUR content by a plasticising effect due to the shortest PVP chains. Moreover, the overlay of the phase and state diagrams highlights the strong impact of the polymer dispersity on the stability of CUR/PVP ASD. ASD formulated with low dispersity PVP are stable on larger temperature and concentration ranges than those formulated with PVP K12.
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In the framework of the development of multi-responsive polymer materials, a well-defined copolymer bearing supramolecular recognition units was designed based on ...2-(dimethylamino)ethyl methacrylate (DMAEMA) and a dialkoxynaphthalene-functionalized monomer (NaphtA). The supramolecular host–guest interactions of this P(DMAEMA-co-NaphtA) copolymer with the electron-deficient CBPQT4+, 4Cl- cyclophane host were studied by 1H NMR spectroscopy, UV–Visible spectroscopy and isothermal titration calorimetry (ITC), revealing, a high association constant of 6.5 × 105 M−1 in water. The addition of CBPQT4+, 4Cl- to a colorless solution of the copolymer in water resulted in a purple solution due to the formation of donor–acceptor inclusion complexes, the intensity being directly proportional to the amount of host added. Investigations on the thermoresponsive behavior of the naphthalene-functionalized copolymer highlighted that the cloud point temperature is directly proportional to the amount of CBPQT4+, 4Cl- host added and can simply be programmed within a temperature window from 30 °C to 48 °C by playing with pH. The dethreading process was studied as function of temperature and anionic exchange of the counterions of the CBPQT4+, 4Cl-. Interestingly, a partial decomplexation was observed by heating the sample above the cloud point temperature while a complete and programmable dethreading was achieved by adding the anionic surfactant sodium dodecyl sulfate (SDS) as a competitive counterion of the host molecule.
The synthesis and original thermoresponsive behavior of hybrid diblock copolypeptides composed of synthetic and recombinant polypeptides are herein reported. A thermoresponsive recombinant ...elastin-like polypeptide was used as a macroinitiator to synthesize a range of poly( l -glutamic acid)-block-elastin-like polypeptide (PGlu-b-ELP) diblock copolypeptides with variable PGlu block lengths. Their temperature-triggered self-assembly in water and in phosphate-buffered saline (PBS) was investigated at the macroscopic scale using complementary techniques such as turbidimetry, dynamic and static light scattering, small-angle neutron scattering, and at the molecular scale by 1H NMR and circular dichroism (CD). In deionized water, PGlu-b-ELP copolypeptides showed one transition from free soluble chains below the transition temperature (T t) of the ELP block to macroscopic aggregates above the T t. In contrast, in PBS, four successive regimes were observed upon increasing temperature: below the T t, copolypeptides were soluble, above the T t, large aggregates appeared and fell apart into discrete and defined spherical nanoparticles at a temperature named critical micellization temperature (CMT), before finally reaching an equilibrium. During the last regime, neutron scattering experiments revealed that the micelle-like structures underwent a densification step and expelled water from their core. In addition, 1H NMR and CD experiments revealed, in deionized water, the formation of type II β-turns into the ELP block upon temperature increase. These β-turns are known to participate in the intrinsic thermoresponsive behavior of the ELPs. In contrast, in PBS, circular dichroism measurements showed an attenuation of folded structure during the self-assembly phase, leading to less cohesive aggregates able to reorganize into nanoparticles at the CMT.
Despite many efforts devoted toward the design of covalent organic frameworks (COFs) at the framework level by selecting the building blocks, their organization in the nano to meso regimes is often ...neglected. Moreover, the importance of processability for their applications has recently emerged and the synthesis of COF nanostructures without agglomeration is still a challenge. Herein, the first example of hybrid COF‐polymer particles for which polymers are used to manipulate the 2D COF growth along a specific direction is reported. The study examines how the nature, chain‐end functionality, and molar mass of the polymer influence the shaping of hybrid 2D boronate ester‐linked COF‐polymer particles. Catechol‐poly(N‐butyl acrylate) leads to the self‐assembly of crystallites into quasi‐spherical structures while catechol‐poly(N‐isopropylacrylamide) mediates the synthesis of raspberry‐like COF‐polymer particles with radial grain orientation. Scanning and transmission electron microscopies (SEM and TEM) and 4D‐STEM‐ACOM (automated crystal orientation mapping) highlight the single‐crystal character of these domains with one plane family throughout the particles. Interestingly, the presence of PNIPAm on the particle surface allows their drying without co‐crystallization and enables their resuspension. Kinetic investigations show that catechol‐PnBuA acts as a modulator and catechol‐PNIPAm induces a template effect, introducing supramolecular self‐assembly properties into particles to create new morphologies with higher structural complexity, beyond the framework level.
Catechol chain‐end functionalized polymers can act either as modulators or impart supramolecular self‐assembly properties into colloidal covalent organic framework (COF)‐5 to mediate the synthesis of well‐defined raspberry‐like particles with a radial single‐crystal orientation. The presence of macromolecular chains on the hybrid particle surface allows their drying without co‐crystallization and enables their resuspension.
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