pH sensitive water-in-water emulsions based on the pullulan and poly(N,N-dimethylacrylamide) aqueous two-phase system

A novel aqueous two-phase system based on pullulan and poly(N,N-dimethylacrylamide) is presented. Furthermore, it is used for the formation of pH sensitive water-in-water emulsions.

Polysaccharide nanoparticles: from fabrication to applications

The present review highlights the developments in polysaccharide nanoparticles with a particular focus on applications in biomedicine, cosmetics and food.

Factors affecting the morphology of some organic and inorganic nanostructures for drug delivery: characterization, modifications, and toxicological perspectives

Introduction: In this review, we aim to highlight the impact of various processes and formulation variables influencing the characteristics of certain surfactant-based nanoconstructs for drug delivery. Areas covered: The review includes the discussion on processing parameters for the preparation of nanoconstructs, especially those made up of surfactants. Articles published in last 15 years (437) were reviewed, 381 articles were selected for data review and most appropriate articles (215) were included in article. Effect of variables such as surfactant concentration and type, membrane additives, temperature, and pH-dependent transitions on morphology has been highlighted along with effect of shape on nanoparticle uptake by cells. Various characterization techniques explored for these nanostructures with respect to size, morphology, lamellarity, distribution, etc., and a separate section on polymeric vesicles and the influence of block copolymers, type of block copolymer, control of block length, interaction of multiple block copolymers on the structure of polymersomes and chimeric nanostructures have been discussed. Finally, applications, modification, degradation, and toxicological aspects of these drug delivery systems have been highlighted. Expert opinion: Parameters influencing the morphology of micelles and vesicles can directly or indirectly affect the efficacy of small molecule cellular internalization as well as uptake in the case of biologicals.[Figure: see text].

Tannic Acid-Mediated Aggregate Stabilization of Poly(N-vinylpyrrolidone)-b-poly(oligo (ethylene glycol) methyl ether methacrylate) Double Hydrophilic Block Copolymers

The self-assembly of block copolymers in aqueous solution is an important field in modern polymer science that has been extended to double hydrophilic block copolymers (DHBC) in recent years. In here, a significant improvement of the self-assembly process of DHBC in aqueous solution by utilizing a linear-brush macromolecular architecture is presented. The improved self-assembly behavior of poly(N-vinylpyrrolidone)-b-poly(oligo(ethylene glycol) methyl ether methacrylate) (PVP-b-P(OEGMA)) and its concentration dependency is investigated via dynamic light scattering (DLS) (apparent hydrodynamic radii ≈ 100-120 nm). Moreover, the DHBC assemblies can be non-covalently crosslinked with tannic acid via hydrogen bonding, which leads to the formation of small aggregates as well (apparent hydrodynamic radius ≈ 15 nm). Non-covalent crosslinking improves the self-assembly and stabilizes the aggregates upon dilution, reducing the concentration dependency of aggregate self-assembly. Additionally, the non-covalent aggregates can be disassembled in basic media. The presence of aggregates was studied via cryogenic scanning electron microscopy (cryo-SEM) and DLS before and after non-covalent crosslinking. Furthermore, analytical ultracentrifugation of the formed aggregate structures was performed, clearly showing the existence of polymer assemblies, particularly after non-covalent crosslinking. In summary, we report on the completely hydrophilic self-assembled structures in solution formed from fully biocompatible building entities in water.

Synthesis and Self-Assembly of Double-Hydrophilic and Amphiphilic Block Glycopolymers

In this report, we present double-hydrophilic block glycopolymers of poly(2-hydroxyethyl methacrylate)- b-poly(2-(β-glucosyloxy)ethyl methacrylate) (PHEMA- b-PGEMA) and amphiphilic block glycopolymers of poly(ethyl methacrylate)- b-PGEMA (PEMA- b-PGEMA) synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The block glycopolymers were prepared in two compositions of P(H)EMA macro-chain transfer agents (CTAs) and similar molecular weights of PGEMA. Structural analysis of the resulting polymers as well as the conversion of (H)EMA and GEMA monomers were determined by 1H NMR spectroscopy. Size exclusion chromatography measurements confirmed both P(H)EMA macro-CTAs and block glycopolymers had a low dispersity ( Đ ≤ 1.5). The synthesized block glycopolymers had a degree of polymerization and a molecular weight up to 222 and 45.3 kg mol-1, respectively. Both block glycopolymers self-assembled into micellar structures in aqueous solutions as characterized by fluorescence spectroscopy, ultraviolet-visible spectroscopy, and dynamic light scattering experiments.

Polysaccharides meet dendrimers to fine-tune the stability and release properties of polyion complex micelles

Dendritic-polysaccharide PIC micelles represent promising delivery systems where dendritic rigidity and polysaccharide stiffness synchronize to determine the stability of the micelles, their kinetics of intracellular drug release, and cytotoxicity.

Poly(ethylene glycol) brush-b-poly(N-vinylpyrrolidone)-based double hydrophilic block copolymer particles crosslinked via crystalline α-cyclodextrin domains

Self-assembly of block copolymers is a significant area of polymer science. The self-assembly of completely water-soluble block copolymers is of particular interest, albeit a challenging task. In the present work the self-assembly of a linear-brush architecture block copolymer, namely poly(N-vinylpyrrolidone)-b-poly(oligoethylene glycol methacrylate) (PVP-b-POEGMA), in water is studied. Moreover, the assembled structures are crosslinked via α-CD host/guest complexation in a supramolecular way. The crosslinking shifts the equilibrium toward aggregate formation without switching off the dynamic equilibrium of double hydrophilic block copolymer (DHBC). As a consequence, the self-assembly efficiency is improved without extinguishing the unique DHBC self-assembly behavior. In addition, decrosslinking could be induced without a change in concentration by adding a competing complexation agent for α-CD. The self-assembly behavior was followed by DLS measurement, while the presence of the particles could be observed via cryo-TEM before and after crosslinking.

Self-assembly of the double hydrophilic block copolymer poly(N-vinylpyrrolidone)-b-poly(oligoethylene glycol methacrylate) and supramolecular crosslinking via α-cyclodextrin in water is presented.

Galactose-Functionalized Double-Hydrophilic Block Glycopolymers and Their Thermoresponsive Self-Assembly Dynamics

Glycopolymers with large galactose units are attractive in biological processes because of their ability to selectively recognize lectin proteins. Recently, thermoresponsive double-hydrophilic block glycopolymers (TDHBGs) have been designed, which allow sugar residues to expose or hide via the lower critical solution temperature (LCST)-type phase transition. In this work, we first synthesize a new type of TDHBGs, composed of a thermoresponsive poly(di(ethylene glycol)methyl ether methacrylate) block and a galactose-functionalized, poly(6- O-vinyladipoyl-d-galactose) (POVNG) block. The LCST can be tuned by varying the size of the POVNG block. Then, we have systematically investigated their thermoresponsive self-assembly behavior, using static and dynamic light scattering techniques, combined with transmission electron microscopy (TEM) imaging. It is found that the TDHBGs possess both micellization and LCST-type transition, and there exist strong interactions between them, depending on the concentration and structure of the TDHBGs. It is particularly interesting that for the same type of TDHBGs under different conditions, such interactions result in rich morphologies of the formed micelles (or nanoparticles) such as spheres, hollow spheres, prolate ellipsoids, crystal-like, and so on, thus potentially enriching their biological applications by noting that they are hepatoma-targeting glycopolymers.

Thermoadaptive Supramolecular α-Cyclodextrin Crystallization-Based Hydrogels via Double Hydrophilic Block Copolymer Templating

Supramolecular hydrogels play a prominent role in contemporary research of hydrophilic polymers. Especially, hydrogels based on α-cyclodextrin/poly(ethylene glycol) (α-CD/PEG) complexation and crystal formation are studied frequently. Here, the effect of double hydrophilic block copolymers (DHBCs) on α-CD/PEG hydrogel properties is investigated. Therefore, a novel DHBC, namely poly(N-vinylpyrrolidone)-b-poly(oligo ethylene glycol methacrylate) (PVP-b-POEGMA), was synthesized via a combination of reversible deactivation radical polymerization and modular conjugation methods. In the next step, hydrogel formation was studied after α-CD addition. Interestingly, DHBC-based hydrogels showed a significant response to thermal history. Heating of the gels to different temperatures led to different mechanical properties after cooling to ambient temperature, i.e., gels with mechanical properties similar to the initial gels or weak flowing gels were obtained. Thus, the hydrogels showed thermoadaptive behavior, which might be an interesting property for future applications in sensing.

Pure hydrophilic block copolymer vesicles with redox- and pH-cleavable crosslinks

The formation and stimuli cleavable crosslinking of completely water drained double hydrophilic block copolymer vesicles is presented.

Self-Assembly of Double Hydrophilic Poly(2-ethyl-2-oxazoline)-b-poly(N-vinylpyrrolidone) Block Copolymers in Aqueous Solution

The self-assembly of a novel combination of hydrophilic blocks in water is presented, namely poly(2-ethyl-2-oxazoline)-b-poly(N-vinylpyrrolidone) (PEtOx-b-PVP). The completely water-soluble double hydrophilic block copolymer (DHBC) is formed via copper-catalyzed polymer conjugation, whereas the molecular weight of the PVP is varied in order to study the effect of block ratio on the self-assembly process. Studies via dynamic light scattering, static light scattering as well as microscopy techniques, e.g., cryo scanning electron microscopy or laser scanning confocal microscopy, show the formation of spherical particles in an aqueous solution with sizes between 300 and 400 nm. Particles of the DHBCs are formed without the influence of external stimuli. Moreover, the efficiency of self-assembly formation relies significantly on the molar ratio of the utilized blocks. The nature of the formed structures relies further on the concentration, and indications of particular and vesicular structures are found.