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This study outlines the microfluidic (MF) controlled self-assembly of polylactide (PLA)-based linear and graft copolymers. The PLA-based copolymers (PLA-Cs) were synthesized through a convenient one-pot/one-step ROP/RAFT technique. Three distinct vinyl monomers-triethylene glycol methacrylate (TEGMA), 2-hydroxypropyl methacrylate (HPMA), and N -(2-hydroxypropyl) methacrylamide (HPMAA) were employed to prepare various copolymers: linear thermoresponsive polylactide- b -poly(triethylene glycol methacrylate) (PLA- b -PTEGMA), graft pseudothermoresponsive poly[ N -(2-hydroxypropyl)] methacrylate- g -polylactide (PHPMA- g -PLA), and graft amphiphilic poly[ N -(2-hydroxypropyl)] methacrylamide- g -polylactide (PHPMAA- g -PLA). The MF technology was utilized for the controlled self-assembly of these PLA-based BCs in a solution, resulting in a range of nanoparticle (NP) morphologies. The thermoresponsive PLA- b -PTEGMA diblock copolymer formed thermodynamically stable micelles (Ms) through kinetically controlled assemblies. Similarly, employing MF channels led to the self-assembly of PHPMA- g -PLA, yielding polymersomes (PSs) with adjustable sizes under the same solution conditions. Conversely, the PHPMAA- g -PLA copolymer generated worm-like particles (Ws). The analysis of resulting nano-objects involves techniques such as transmission electron microscopy, dynamic light scattering investigations (DLS), and small-angle X-ray scattering (SAXS). More specifically, the thermoresponsive behavior of PLA- b -PTEGMA and PHPMA- g -PLA nano-objects is validated through variable-temperature DLS, TEM, and SAXS methods. Furthermore, the study explored the specific interactions between the formed Ms, PSs, and/or Ws with proteins in human blood plasma, utilizing isothermal titration calorimetry., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Electrostatic interactions between charged macromolecules are ubiquitous in biological systems, and they are important also in materials design. Attraction between oppositely charged molecules is often interpreted as if the molecules had a fixed charge, which is not affected by their interaction. Less commonly, charge regulation is invoked to interpret such interactions, i.e., a change of the charge state in response to a change of the local environment. Although some theoretical and simulation studies suggest that charge regulation plays an important role in intermolecular interactions, experimental evidence supporting such a view is very scarce. In the current study, we used a model system, composed of a long polyanion interacting with cationic oligolysines, containing up to 8 lysine residues. We showed using both simulations and experiments that while these lysines are only weakly charged in the absence of the polyanion, they charge up and condense on the polycations if the pH is close to the p K a of the lysine side chains. We show that the lysines coexist in two distinct populations within the same solution: (1) practically nonionized and free in solution; (2) highly ionized and condensed on the polyanion. Using this model system, we demonstrate under what conditions charge regulation plays a significant role in the interactions of oppositely charged macromolecules and generalize our findings beyond the specific system used here., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

The influence of hydrophobicity on formation, stability, and size of pH-responsive methacryloylated oligopeptide-based polymer nanoparticles has been studied by dynamic light scattering (DLS), transmission electron microscopy (Cryo-TEM), and NMR. Different polyanions/surfactant systems have been studied at constant polymer concentration and within a broad range of surfactant concentrations. The two newly synthesized pH-sensitive hydrophobic polyanions, poly(N(ω)-methacryloyl glycyl-L-leucine) and poly(N(ω)-methacryloyl glycyl-L-phenylalanyl-L-leucinyl-glycine), and three nonionic surfactants (Brij97, Brij98, and Brij700) have been investigated. The surfactants were different in the length of hydrophilic poly(ethylene oxide) (PEO) chain. In surfactant-free solution at basic pH, the polyanions form hydrophobic domains. In the presence of a surfactant, our results prove the complex formation at high pH between the nonionic surfactant and the polyelectrolyte; a pearl-necklace structure is formed. At low pH below critical pH (pH(tr)), reversible nanoscale structures occur in solutions for all systems. The detailed mechanism of the formation of pH-sensitive nanoparticles from polymer-surfactant complex with varying pH is established. Our results suggest that the polymer hydrophobicity is of primary importance in pretransitional behavior of the complex. Once preliminary nanoparticle nuclei are formed, the hydrophobicity of the polymer plays a minor role on further behavior of formed nanostructures. The subsequent transformation of nanoparticles is determined by the surfactant hydrophilicity, the length of hydrophilic tail that prevents further aggregation due to steric repulsions.

In this work we report a new type of pH-responsive micelle-like nanoparticle. Reversible nanoscale structures are formed in solutions of a pH-sensitive hydrophobic polyelectrolyte, poly( N-methacryloyl- l-valine) or poly( N-methacryloyl- l-phenylalanine), and nonionic surfactant (Brij 98) in the presence of hydrochloric acid. The influence of composition and pH on particles size and shape was investigated by a variety of methods. An entity's size and polydispersity could be varied in a broad range making them a perspective candidate as a drug carrier. Unlike the case of typical micelles, our results indicate the presence of cavities in the formed particles. A hypothetical model of a nanoparticle and mechanism of formation are proposed.