Synthesis of an Amphiphilic Miktoarm Star Terpolymer for Self-Assembly into Patchy Polymersomes

Click Chemistry in Polymersome Technology

Polymersomes, self-assembled nanoparticles composed of amphiphilic block copolymers, have emerged as promising versatile nanovesicles with various applications, such as drug delivery, medical imaging, and diagnostics. The integration of click chemistry reactions, specifically the copper [I]-catalysed azide-alkyne cycloaddition (CuAAC), has greatly expanded the functionalisation and bioconjugation capabilities of polymersomes and new drugs, being this synergistic combination explored in this review. It also provides up-to-date examples of previous incorporations of click-compatible moieties (azide and alkyne functional groups) into polymer building blocks, enabling the "click" attachment of various functional groups and ligands, delving into the diverse range of click reactions that have been reported and employed for polymersome copolymer synthesis and the modification of polymersome surfaces, including ligand conjugation and surface modification. Overall, this review explores the current state-of-the-art of the combinatory usage, in recent years, of polymersomes with the click chemistry reaction, highlighting examples of studies of their synthesis and functionalisation strategies.

Membrane and Lumen-Compartmentalized Polymersomes for Biocatalysis and Cell Mimics

Compartmentalization is a crucial feature of a natural cell, manifested in cell membrane and inner lumen. Inspired by the cellular structure, multicompartment polymersomes (MCPs), including membrane-compartmentalized polymersomes and lumen-compartmentalized polymersomes (polymersomes-in-polymersomes), have aroused great expectations for biological applications such as biocatalysis and cell mimics in the past decades. Compared with traditional polymersomes, MCPs have advantages in encapsulating multiple enzymes separately for multistep enzymatic cascade reactions. In this review, first, the design principles and preparation methods of membrane-compartmentalized and lumen-compartmentalized polymersomes are summarized. Next, recent advances of MCPs as nanoreactors and cell mimics to mimic subcellular organelles or artificial cells are discussed. Finally, the future research directions of MCPs are prospected.

Single Functional Group Platform for Multistimuli Responsivities: Tertiary Amine for CO2/pH/ROS-Triggered Cargo Release in Nanocarriers

The design of multistimuli-responsive soft nanoparticles (NPs) often presents synthetic complexities and limited breadth in exploiting changes surrounding physiological environments. Nanocarriers that could collectively take advantage of several endogenous stimuli can offer a powerful tool in nanomedicine. Herein, we have capitalized on the chemical versatility of a single tertiary amine to construct miktoarm polymer-based nanocarriers that respond to dissolved CO2, varied pH, reactive oxygen species (ROS), and ROS + CO2. Curcumin (Cur), an anti-inflammatory phytopharmaceutic, was loaded into micelles, and we validated the sensitivity of the tertiary amine in tuning Cur release. An in vitro evaluation indicated that Cur encapsulation strongly suppressed its toxicity at high concentrations, significantly inhibited nigericin-induced secretion of interleukin-1β by THP-1 macrophages, and the proportion of M2/M1 (anti-inflammatory/pro-inflammatory macrophages) was higher for Cur-loaded NPs than for free Cur. Our approach highlights the potential of a simple-by-design strategy in expanding the scope of polymeric NPs in drug delivery.

MPC-n (IgG) improves long-term cognitive impairment in the mouse model of repetitive mild traumatic brain injury

BACKGROUND

Contact sports athletes and military personnel who suffered a repetitive mild traumatic brain injury (rmTBI) are at high risk of neurodegenerative diseases such as advanced dementia and chronic traumatic encephalopathy (CTE). However, due to the lack of specific biological indicators in clinical practice, the diagnosis and treatment of rmTBI are quite limited.

METHODS

We used 2-methacryloyloxyethyl phosphorylcholine (MPC)-nanocapsules to deliver immunoglobulins (IgG), which can increase the delivery efficiency and specific target of IgG while reducing the effective therapeutic dose of the drug.

RESULTS

Our results demonstrated that MPC-capsuled immunoglobulins (MPC-n (IgG)) significantly alleviated cognitive impairment, hippocampal atrophy, p-Tau deposition, and myelin injury in rmTBI mice compared with free IgG. Furthermore, MPC-n (IgG) can also effectively inhibit the activation of microglia and the release of inflammatory factors.

CONCLUSIONS

In the present study, we put forward an efficient strategy for the treatment of rmTBI-related cognitive impairment and provide evidence for the administration of low-dose IgG.

Stimuli-Responsive Miktoarm Polymer-Based Formulations for Fisetin Delivery and Regulatory Effects in Hyperactive Human Microglia

Branched star polymers offer exciting opportunities in enhancing the efficacy of nanocarriers in delivering biologically active lipophilic agents. We demonstrate that the star polymeric architecture can be leveraged to yield soft nanoparticles of vesicular morphology with precisely located stimuli-sensitive chemical entities. Amphiphilic stars of AB₂ (A = PEG, B = PCL) composition with/without oxidative stress or reduction responsive units at the core junction of A and B arms, are constructed using synthetic articulation. Fisetin, a natural flavonoid with remarkable anti-inflammatory and antioxidant properties, but of limited clinical value due to its poor aqueous solubility, was physically encapsulated into miktoarm star-derived aqueous polymersomes. We evaluated polymersomes and fisetin separately, and in combination, in human microglia (HMC3), to show if (i) polymersomes are toxic; (ii) fisetin reduces the abundance of reactive oxygen species (ROS); and (iii) fisetin modulates the activation of ERK1/2. These signaling molecules and pathways are implicated in inflammatory processes and cell survival. Fisetin, both incorporated and non-incorporated into polymersomes, reduced ROS and ERK1/2 phosphorylation in lipopolysaccharide-treated human microglia, normalizing excessive oxidative stress and ERK-mediated signaling. This article is protected by copyright. All rights reserved.

Polymersomes: Soft Nanoparticles from Miktoarm Stars for Applications in Drug Delivery

Self-assembly of amphiphilic macromolecules has provided an advantageous platform to address significant issues in a variety of areas, including biology. Such soft nanoparticles with a hydrophobic core and hydrophilic corona, referred to as micelles, have been extensively investigated for delivering lipophilic therapeutics by physical encapsulation. Polymeric vesicles or polymersomes with similarities in morphology to liposomes continue to play an essential role in understanding the behavior of cell membranes and, in addition, have offered opportunities in designing smart nanoformulations. With the evolution in synthetic methodologies to macromolecular precursors, the construction of such assemblies can now be modulated to tailor their properties to match desired needs. This review brings into focus the current state-of-the-art in the design of polymersomes using amphiphilic miktoarm star polymers through a detailed analysis of the synthesis of miktoarm star polymers with tuned lengths of varied polymeric arms, their self-assembly, and applications in drug delivery.

Functionalized Particles Designed for Targeted Delivery

Pure bioactive compounds alone can only be exceptionally administered in medical treatment. Usually, drugs are produced as various forms of active compounds and auxiliary substances, combinations assuring the desired healing functions. One of the important drug forms is represented by a combination of active substances and particle-shaped polymer in the nano- or micrometer size range. The review describes recent progress in this field balanced with basic information. After a brief introduction, the paper presents a concise overview of polymers used as components of nano- and microparticle drug carriers. Thereafter, progress in direct synthesis of polymer particles with functional groups is discussed. A section is devoted to formation of particles by self-assembly of homo- and copolymer-bearing functional groups. Special attention is focused on modification of the primary functional groups introduced during particle preparation, including introduction of ligands promoting anchorage of particles onto the chosen living cell types by interactions with specific receptors present in cell membranes. Particular attention is focused on progress in methods suitable for preparation of particles loaded with bioactive substances. The review ends with a brief discussion of the still not answered questions and unsolved problems.

Synthesis, Characterization, and Dynamic Behavior of Well-defined Dithiomaleimide-functionalized Maltodextrins

:

Maltodextrins have an increasing number of biomedical and industrial applications due to their attractive physicochemical properties such as biodegradability and biocompatibility. Herein, we describe the development of a synthetic pathway and characterization of thiol-responsive maltodextrin conjugates with dithiomaleimide linkages. 19F NMR studies were also conducted to demonstrate the exchange dynamics of the dithiomaleimide-functionalized sugar end groups.

Rational design of nonlinear crystalline-amorphous-responsive terpolymers for pH-guided fabrication of 0D–3D nano-objects

Crystallization/pH-induced self-assembly of starlike and tadpole-linear terpolymers allowed the formation of 0D spheres/vesicles, 1D cylinders, 2D platelets/nanosheets and 3D tadpoles/dendritic vesicles.

Directed Insertion of Light-Activated Proteorhodopsin into Asymmetric Polymersomes from an ABC Block Copolymer

Nanoscopic artificial vesicles containing functional protein transporters are fundamental for synthetic biology. Energy-providing modules, such as proton pumps, are a basis for simple nanoreactors. We report on the first insertion of a functional transmembrane protein into asymmetric polymersomes from an ABC triblock copolymer. The polymer with the composition poly(ethylene glycol)-poly(diisopropylaminoethyl methacrylate)-poly(styrenesulfonate) (PEG-PDPA-PSS) was synthesized by sequential controlled radical polymerization. PEG and PSS are two distinctively different hydrophilic blocks, allowing for a specific orientation of our protein, the light-activated proton pump proteorhodopsin (PR), into the final proteopolymersome. A very interesting aspect of the PEG-PDPA-PSS triblock copolymers is that it allowed for simultaneous vesicle formation and oriented insertion of PR simply by adjusting the pH. The intrinsic positive charge of PR's intracellular surface was enhanced by a His-tag, which aligns readily with the negative charges of the PSS on the outside of the polymersomes. The directed insertion of PR was confirmed by a light-dependent pH change of the proteopolymersome solution, indicating the intended orientation. We have hereby demonstrated the first successful oriented insertion of a proton pump into an artificial asymmetric membrane.

pH-Responsive Zwitterionic Copolymer DHA-PBLG-PCB for Targeted Drug Delivery: A Computer Simulation Study

In this work, the self-assembled behaviors of zwitterionic copolymer docosahexaenoic acid- b-poly(γ-benzyl-l-glutamate)- b-poly(carboxybetaine methacrylate) (DHA-PBLG-PCB) and the loading and release mechanism of the anticancer drug doxorubicin (DOX) was investigated via computer simulations. The effects of polymer concentration, drug content, and pH on polymeric micelles were explored by dissipative particle dynamics (DPD) simulations. Simulation results show that DHA-PBLG₁₅-PCB₁₀ can self-assemble into core-shell micelles; in addition, the drug-loaded micelles have a pH-responsive feature. DOX can be encapsulated into the core-shell micelle under normal physiological pH conditions, whereas it can be released under acidic pH conditions. The self-assembled behaviors of copolymer DHA-PBLG-PEG were also studied to have a comparison with those of DHA-PBLG-PCB. The DHA-PBLG₁₅-PCB₁₀ system has a stable structure and it has a great potential to serve as drug delivery vehicles for targeted drug delivery.

Complexes of magnetic nanospheres with amphiprotic polymer-Zn systems for the selective isolation of lactoferrin

Amphiprotic polymer-Zn complex magnetic nanospheres, termed Fe₃O₄@PCL-CMC-Zn, are designed and prepared via a step-wise synthetic strategy. Hydrophobic polycaprolactone (PCL) is firstly coated onto the magnetic Fe₃O₄ nanospheres, and then hydrophilic carboxymethylcellulose (CMC) is grafted onto the hydrophobic PCL blocks via an esterification reaction, followed by finally chelating with Zn²⁺ ions. The homogeneous core-shell structure and fastened amphiprotic polymer layer provide the as-prepared Fe₃O₄@PCL-CMC-Zn magnetic nanospheres with improved protein binding behavior, and the chelated Zn²⁺ offers the nanospheres favorable adsorption selectivity towards apo-lactoferrin. The adsorption capacity of apo-lactoferrin is high, up to 615.3 mg g^-1. The exploitation of FeCl₃ as a stripping reagent not only provides efficient recovery of the adsorbed apo-lactoferrin, i.e. a recovery of 83.2%, but also achieves the restoration of the lactoferrin structure. The Fe₃O₄@PCL-CMC-Zn magnetic nanospheres are then employed as a sorbent for the selective isolation of lactoferrin from human colostrum samples, obtaining high-purity lactoferrin as demonstrated by SDS-PAGE and Q-TOF LC-MS assays.

Rational design of substituted maleimide dyes with tunable fluorescence and solvafluorochromism

A series of maleimide derivatives were systematically designed and synthesized with tunable fluorescent properties. The facile modifications herein provide a simple methodology to expand the scope of maleimide-based dyes and also provide insight into the relationship between substitution pattern and optical properties.

Cargo Release from Polymeric Vesicles under Shear

In this paper we study the release of cargo from polymeric nano-carriers under shear. Vesicles formed by two star block polymers- A 12 B 6 C 2 ( A B C ) and A 12 B 6 A 2 ( A B A )-and one linear block copolymer- A 14 B 6 ( A B ), are investigated using dissipative particle dynamics (DPD) simulations. A - and C -blocks are solvophobic and B -block is solvophilic. The three polymers form vesicles of different structures. The vesicles are subjected to shear both in bulk and between solvophobic walls. In bulk shear, the mechanisms of cargo release are similar for all vesicles, with cargo travelling through vesicle membrane with no preferential release location. When sheared between walls, high cargo release rate is only observed with A B C vesicle after it touches the wall. For A B C vesicle, the critical condition for high cargo release rate is the formation of wall-polymersome interface after which the effect of shear rate in promoting cargo release is secondary. High release rate is achieved by the formation of solvophilic pathway allowing cargo to travel from the vesicle cavity to the vesicle exterior. The results in this paper show that well controlled target cargo release using polymersomes can be achieved with polymers of suitable design and can potentially be very useful for engineering applications. As an example, polymersomes can be used as carriers for surface active friction reducing additives which are only released at rubbing surfaces where the additives are needed most.

Large-scale preparation of a 3D patchy surface with dissimilar dendritic amphiphiles

We show here the first example of the large-scale surface decoration of a macroscopic and porous monolith with dissimilar micropatches. Branched polyethylenimine (PEI) is alkylated with poly(propylene glycol) (PPG), leading to a reverse-micelle-like dendritic amphiphile of PEI@PPG. Peralkylation and partial quaternization of the residual amino groups of PEI@PPG produces a cationic dendritic amphiphile of PEI-N⁺@PPG. The two dendritic amphiphiles jointly stabilize a water-in-oil high-internal-phase emulsion to prepare open-cellular monoliths of macroscopic size, with the monolith pore surface dictated by the cationic and neutral dendritic amphiphiles. The amino groups of the neutral amphiphile are further derivatized into anionic dithiocarbamates. The resulting monolith, along with the dissimilar functional patches on the surface, simultaneously eliminates multiple anionic and cationic micropollutants from water to very low residues, and affords the pH-triggered sequential release. Our strategy of using dissimilar dendritic amphiphiles rather than block copolymers as surface building blocks can confer the resulting surface with robust and predesigned microenvironments besides the conventional coacervate structure, and thus can afford more functions.

Thermoresponse and self-assembly of an ABC star quarterpolymer with O2 and redox dual-responsive Y junctions

The stimuli-tunable LCST-type phase transition and self-assembly behaviors of a multi-responsive 3-miktoarm star bearing O₂/redox-sensitive and H-bond-switchable Y junctions were revealed.

Vesicles in Multiple Shapes: Fine-Tuning Polymersomes' Shape and Stability by Setting Membrane Hydrophobicity

Amphiphilic block-copolymers are known to self-assemble into micelles and vesicles. In this paper, we discuss the multiple options between and beyond these boundaries using amphiphilic AB diblock and ABC triblock copolymers. We adjust the final structure reached by the composition of the mixture, by the preparation temperature, and by varying the time-scale of formation. This leads to the formation of vesicles and micelles, but also internal micelles in larger sheets, lamellar vesicles, and closed tubes, thus broadening the amount of self-assembly structures available and deepening our understanding of them.

Biocompatible pH-responsive nanoparticles with a core-anchored multilayer shell of triblock copolymers for enhanced cancer therapy

Drug nanocarriers are synthesised via a facile self-assembly approach using gold nanoparticles (Au NPs) as a structural core. The nanocarriers feature a multilayer shell of POEGMA-PDPA-PMPC triblock copolymers with a chain-end thiol functional group for anchoring to the Au NP surface. This water-soluble triblock copolymer was synthesised via atom transfer radical polymerisation (ATRP) from a bi-functional initiator containing a disulphide bridge. The resultant nanocarriers exhibit high biocompatibility plus excellent colloidal stability and antifouling capability in bio-media (50% PBS/FBS). Encapsulation and release of a hydrophobic drug can be effectively triggered by a pH-stimulus. Meanwhile drug-loaded nanocarriers show enhanced efficacy towards cancer cells compared to plain drug.

Multi-Dimensional Self-Assembly of a Dual-Responsive ABC Miktoarm Star Terpolymer

This letter reports the first 2D self-assembly of ABC miktoarm star terpolymers based on dual-responsive polycaprolactone-arm-poly(N-isopropylacrylamide)-arm-poly(2-dimethylaminoethyl methacrylate) (μ-CID), which self-assembled into multilayer nanosheets comprising polycaprolactone single crystals in tetrahydrofuran (THF)/methanol mixed solvents. Interestingly, the nanosheets showed pH-responsive morphological transitions in aqueous solutions, yielding multidimensional assemblies, including 2D hexagonal aggregates, patchy nanofibrils, and patchy vesicles, at different pH values. The nanosheets also exhibited thermoresponsive transition to spherical patchy micelles at a temperature above the lower critical solution temperature (LCST) of the poly(N-isopropylacrylamide) block. This study offers a novel system for fundamental study on the self-assembly of miktoarm star terpolymers.

Synthesis and self-assembly of a dual-responsive monocleavable ABCD star quaterpolymer

A modularly synthesized core-functionalized PEG-PSt-PCL-PAA miktoarm star can self-assemble into hollow nanocapsules that are sensitive to pH/redox stimuli and H-bond/polyion complexation.

Reversible surface functionalisation of emulsion-templated porous polymers using dithiophenol maleimide functional macromolecules

Reversible, easy-to-monitor approach to the surface functionalisation of thiol–acrylate polyHIPEs that can be utilised in a wide range of applications.

Reversible Regulation of Thermoresponsive Property of Dithiomaleimide-Containing Copolymers via Sequential Thiol Exchange Reactions

The facile and efficient functionalization of thermoresponsive polymers based on sequential, reversible thiol-exchange reactions is reported. Well-defined dithiomaleimide-containing polymers have been synthesized via Cu(0)-mediated SET-LRP and characterized by ¹H NMR and size exclusion chromatography (SEC). The resulting thermosensitive copolymers were subsequently reacted with various thiols to demonstrate the applicability of the strategy, and the thiol-exchange reaction was found to be very fast and efficient. The cloud point of the prepared copolymers can be continually and reversibly tuned, and desirable functionality can be dynamically exchanged upon sequential addition of functional thiol reagents. Through the substitution by thioglucose, an ON-to-OFF switch for fluorescence of the copolymers along with the generation of a glycopolymer was achieved.