pH-Driven Morphological Diversity in Poly[n-Butyl Acrylate-block-(2-(Dimethylamino)Ethyl Acrylate)] Amphiphilic Copolymer Solutions

Curcumin-Loaded PnBA-b-POEGA Nanoformulations: A Study of Drug-Polymer Interactions and Release Behavior

The current study focuses on the development of innovative and highly-stable curcumin (CUR)-based therapeutics by encapsulating CUR in biocompatible poly(n-butyl acrylate)-block-poly(oligo(ethylene glycol) methyl ether acrylate) (PnBA-b-POEGA) micelles. State-of-the-art methods were used to investigate the encapsulation of CUR in PnBA-b-POEGA micelles and the potential of ultrasound to enhance the release of encapsulated CUR. Dynamic light scattering (DLS), attenuated total reflection Fourier transform infrared (ATR-FTIR), and ultraviolet-visible (UV-Vis) spectroscopies confirmed the successful encapsulation of CUR within the hydrophobic domains of the copolymers, resulting in the formation of distinct and robust drug/polymer nanostructures. The exceptional stability of the CUR-loaded PnBA-b-POEGA nanocarriers over a period of 210 days was also demonstrated by proton nuclear magnetic resonance (¹H-NMR) spectroscopy studies. A comprehensive 2D NMR characterization of the CUR-loaded nanocarriers authenticated the presence of CUR within the micelles, and unveiled the intricate nature of the drug-polymer intermolecular interactions. The UV-Vis results also indicated high encapsulation efficiency values for the CUR-loaded nanocarriers and revealed a significant influence of ultrasound on the release profile of CUR. The present research provides new understanding of the encapsulation and release mechanisms of CUR within biocompatible diblock copolymers and has significant implications for the advancement of safe and effective CUR-based therapeutics.

Nano-Assemblies from Amphiphilic PnBA-b-POEGA Copolymers as Drug Nanocarriers

The focus of this study is the development of highly stable losartan potassium (LSR) polymeric nanocarriers. Two novel amphiphilic poly(n-butyl acrylate)-block-poly(oligo(ethylene glycol) methyl ether acrylate) (PnBA-b-POEGA) copolymers with different molecular weight (M_w) of PnBA are synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization, followed by the encapsulation of LSR into both PnBA-b-POEGA micelles. Based on dynamic light scattering (DLS), the PnBA₃₀-b-POEGA₇₀ and PnBA₂₇-b-POEGA₇₃ (where the subscripts denote wt.% composition of the components) copolymers formed micelles of 10 nm and 24 nm in water. The LSR-loaded PnBA-b-POEGA nanocarriers presented increased size and greater mass nanostructures compared to empty micelles, implying the successful loading of LSR into the inner hydrophobic domains. A thorough NMR (nuclear magnetic resonance) characterization of the LSR-loaded PnBA-b-POEGA nanocarriers was conducted. Strong intermolecular interactions between the biphenyl ring and the butyl chain of LSR with the methylene signals of PnBA were evidenced by 2D-NOESY experiments. The highest hydrophobicity of the PnBA₂₇-b-POEGA₇₃ micelles contributed to an efficient encapsulation of LSR into the micelles exhibiting a greater value of %EE compared to PnBA₃₀-b-POEGA₇₀ + 50% LSR nanocarriers. Ultrasound release profiles of LSR signified that a great amount of the encapsulated LSR is strongly attached to both PnBA₃₀-b-POEGA₇₀ and PnBA₂₇-b-POEGA₇₃ micelles.

Self-assembly of dextran - b - deoxycholic acid polyester copolymers: Copolymer composition and self-assembly procedure tune the aggregate size and morphology

Self-assembly potential of new amphiphilic block copolymers containing dextran (M_n 4500, 8000, 15,000) and a semi-rigid deoxycholic acid-oligoethyleneglycol polyester (M_n 2500-8800, 2 or 4 ethyleneglycol units), was evaluated as a function of copolymer composition and self-assembly procedure, using dynamic light scattering and transmission electron microscopy. Addition of copolymer solution to water provided small star-like micelles (∼ 100 nm), while addition of water to copolymer solution led to various morphologies and sizes (60-600 nm), depending on polymer composition. Worm-like micelles were obtained from a copolymer containing dextran with M_n 4500 and 66 wt% polyester, and vesicles were formed by copolymers prepared from dextran with M_n 8000 and containing 46 wt% polyester. Presence of a longer oligoethyleneglycol decreased the size of micelles and vesicles due to an enhanced flexibility of the polyester hydrophobic block. The results allow the selection of the most appropriate parameters to obtain the desired aggregate characteristics.

Effects of Chemical Modifications on the Thermoresponsive Behavior of a PDMAEA-b-PNIPAM-b-POEGA Triblock Terpolymer

In this work, the synthesis, selective chemical modifications, and self-assembly behavior in aqueous media of a novel poly(2-(dimethylamino)ethyl acrylate)₂₀-b-poly(N-isopropylacrylamide)₁₁-b-poly(oligo ethylene glycol methyl ether acrylate)₁₈ (PDMAEA₂₀-b-PNIPAM₁₁-b-POEGA₁₈) dual-responsive (pH and temperature) and triply hydrophilic amino-based triblock terpolymer are reported. The amine functional triblock terpolymer was synthesized by sequential reversible addition fragmentation chain transfer polymerization (RAFT) polymerization and molecularly characterized by size exclusion chromatography (SEC) and ¹H-NMR spectroscopy that evidenced the success of the three-step polymerization scheme. The tertiary amine pendant groups of the PDMAEA block were chemically modified in order to produce the Q₁PDMAEA₂₀-b-PNIPAM₁₁-b-POEGA₁₈ as well as the Q₆PDMAEA₂₀-b-PNIPAM₁₁-b-POEGA₁₈ quaternized triblock terpolymers (Q₁ and Q₆ prefixes show the number of carbon atoms (C1 and C6) attached on the PDMAEA groups) using methyl iodide (CH₃I) and 1-iodohexane (C₆H₁₃I) as the quaternizing agents and the SPDMAEA₂₀-b-PNIPAM₁₁-b-POEGA₁₈ sulfobetainized triblock terpolymer using 1,3 propanesultone (C₃H₆O₃S) as the sulfobetainization agent. The self-assembly properties of the triblock terpolymers in aqueous solutions upon varying temperature and solution pH were studied by light scattering and fluorescence spectroscopy experiments. The novel triblock terpolymers self-assemble into nanosized aggregates upon solution temperature rise above the nominal lower critical solution temperature (LCST) of the temperature-responsive PNIPAM block. The remarkable stimuli-responsive self-assembly behavior of the novel triblock terpolymers in aqueous media make them interesting candidates for biomedical applications in the fields of drug and gene delivery.