遊佐 真一

Abstract A dual zwitterionic diblock copolymer (M₁₀₀C₁₀₀) consisting of poly(2‐(methacryloyloxy)ethyl phosphorylcholine) (PMPC, M) and poly(3‐((2‐(methacryloyloxy)ethyl) dimethylammonio) propionate) (PCBMA, C) is synthesized via reversible addition‐fragmentation chain transfer (RAFT) polymerization. A double hydrophilic diblock copolymer (M₁₀₀S₁₀₀) consist of PMPC and anionic poly(3‐sulfopropyl methacrylate potassium salt) (PMPS, S) is synthesized via RAFT. The degrees of polymerization of each block are 100. The charges of PMPC are neutralized intramolecularly. At neutral pH, the charges in PCBMA are also neutralized intramolecularly due to its carboxybetaine structure. Under acidic conditions, PCBMA exhibits polycation behavior as the pendant carboxy groups become protonated, forming cationic tertiary amine groups. PMPS shows permanent anionic nature independent of pH. Charge neutralized mixture of cationic M₁₀₀C₁₀₀ and anionic M₁₀₀S₁₀₀ in acidic aqueous solution forms water‐soluble polyion complex (PIC) micelle owing to electrostatic attractive interactions. The core is composed of the cationic PCBMA and anionic PMPS blocks, with the PMPC blocks serving as shells that covered the core surface, forming spherical core–shell PIC micelles. Above pH 4 the pendant carboxy groups in PCBMA undergo deprotonation, transitioning to a zwitterionic state, thereby eliminating the cationic charge in PCBMA. Therefore, above pH 4 the PIC micelles are dissociated due to the disappearance of the charge interactions.

Gas marbles are a new family of particle-stabilized soft dispersed system with a soap bubble-like air-in-water-in-air structure. Herein, stimulus-responsive character is successfully introduced to a gas marble system for the first time using polymer particles carrying a poly(tertiary amine methacrylate) (pKa ≈7) steric stabilizer on their surfaces as a particulate stabilizer. The gas marbles exhibited long-term stability when transferred onto the planar surface of liquid water, provided that the solution pH of the subphase is basic and neutral. In contrast, the use of acidic solutions led to immediate disintegration of the gas marbles, resulting in release of the inner gas. The critical minimum solution pH required for long-term gas marble stability correlates closely with the known pKa value for the poly(tertiary amine methacrylate) stabilizer. It also demonstrates amphibious motions of the gas marbles.

Liquid marbles (LMs) can be prepared by adsorption of hydrophobic particles at the air-liquid interface of a water droplet. LMs have been studied for their application as microreaction vessels. However, their opaqueness poses challenges for internal observation. Liquid plasticines (LPs), akin to LMs, can be prepared by the adsorption of hydrophobic particles with a diameter of 50 nm or less, at the air-liquid interface of a water droplet. Unlike LMs, LPs are transparent, allowing for internal observation, thus presenting promising applications as reactors and culture vessels on a microliter scale. In this study, the surface of silica particles, approximately 20 nm in diameter, was rendered hydrophobic to prepare hydrophobic silica particles (SD0). A small amount of poly(2-(diisopropylamino)ethyl methacrylate) (PDPA) was then grafted onto the surface of SD0, yielding SD1. SD0 particles exhibited consistent hydrophobicity irrespective of the environmental pH atmosphere. Under acidic conditions, SD1 became hydrophilic due to the protonation of pendant tertiary amines in the grafted PDPA chains. However, SD1 alone was unsuitable for LP preparation due to its high surface wettability regardless of atmospheric pH, attributable to the presence of PDPA-grafted chains. Therefore, to prepare pH-responsive LP, SD1 and SD0 were mixed (SD1/SD0 = 3/7). Upon exposure to HCl gas, these LPs ruptured, with the leaked water from the LPs being absorbed by adjacent paper. Moreover, clear LPs, prepared using an aqueous solution containing a water-soluble photoacid generator (PAG), disintegrated upon exposure to light as PAG generated acid, leading to LP breakdown. In summary, pH-responsive LPs, capable of disintegration under acidic conditions and upon light irradiation, were successfully prepared in this study.

AB-type and BAB-type betaine block copolymers composed of a carboxybetaine methacrylate and a sulfobetaine methacrylate, PGLBT-b-PSPE and PSPE-b-PGLBT-b-PSPE, respectively, were synthesized by one-pot RAFT polymerization. By optimizing the concentration of the monomer, initiator, and chain transfer agent, block extension with precise ratio control was enabled and a full conversion (~99%) of betaine monomers was achieved at each step. Two sets (total degree of polymerization: ~300 and ~600) of diblock copolymers having four different PGLBT:PSPE ratios were prepared to compare the influence of block ratio and molecular weight on the temperature-responsive behavior in aqueous solution. A turbidimetry and dynamic light scattering study revealed a shift to higher temperatures of the cloud point and micelle formation by increasing the ratio of PSPE, which exhibit upper critical solution temperature (UCST) behavior. PSPE-dominant diblocks created spherical micelles stabilized by PGLBT motifs, and the transition behavior diminished by decreasing the PSPE ratio. No particular change was found in the diblocks that had an identical AB ratio. This trend reappeared in the other set whose entire molecular weight approximately doubled, and each transition point was not recognizably impacted by the total molecular weight. For triblocks, the PSPE double ends provided a higher probability of interchain attractions and resulted in a more turbid solution at higher temperatures, compared to the diblocks which had similar block ratios and molecular weights. The intermediates assumed as network-like soft aggregates eventually rearranged to monodisperse flowerlike micelles. It is expected that the method for obtaining well-defined betaine block copolymers, as well as the relationship of the block ratio and the chain conformation to the temperature-responsive behavior, will be helpful for designing betaine-based polymeric applications.

Block copolymers (PmMn; P20M101 and P100M98) comprising poly(2-(methacryloyloxy)ethylphosphorylcholine) (PMPC, P) containing biocompatible phosphorylcholin pendants and cationic poly((3-acryloylaminopropyl) trimethylammonium chloride) (PMAPTAC, M) were synthesized via a controlled radical polymerization method. The degrees of polymerization of the PMPC and PMAPTAC segments are denoted by subscripts (PmMn). The mixture of cationic PmMn and anionic sodium chondroitin sulfate C (CS) with the pendant anionic carboxylate and sulfonate groups formed polyion complex (PIC) aggregates in phosphate-buffered saline. A charge-neutralized mixture of P20M101 with CS formed P20M101/CS PIC vesicles with a hydrodynamic radius (Rh) of 97.2 nm, zeta potential of ca. 0 mV, and aggregation number (Nagg) of 23,044. PMPC shells covered the surface of the PIC vesicles. The mixture of P100M98 and CS formed PIC spherical micelles with the PIC core and hydrophilic PMPC shells. The Rh, zeta potential, and Nagg of the PIC micelles were 26.4 nm, ca. 0 mV, and 404, respectively. At pH < 4, the carboxylate anions in CS were protonated. Thus, the charge balance in the PIC micelles shifted to decrease the core density owing to the electrostatic repulsions of the excess cations in the core. The PIC micelles dissociated at a NaCl concentration ≥0.6 M owing to the charge screening effect. The positively charged PIC micelles with excess P100M98 can encapsulate anionic dyes owing to electrostatic interaction.

Polymeric drug delivery technology, which allows for medicinal ingredients to enter a cell more easily, has advanced considerably in recent decades. Innovative medication delivery strategies use biodegradable and bio-reducible polymers, and progress in the field has been accelerated by future possible research applications. Natural polymers utilized in polymeric drug delivery systems include arginine, chitosan, dextrin, polysaccharides, poly(glycolic acid), poly(lactic acid), and hyaluronic acid. Additionally, poly(2-hydroxyethyl methacrylate), poly(N-isopropyl acrylamide), poly(ethylenimine), dendritic polymers, biodegradable polymers, and bioabsorbable polymers as well as biomimetic and bio-related polymeric systems and drug-free macromolecular therapies have been employed in polymeric drug delivery. Different synthetic and natural biomaterials are in the clinical phase to mitigate different diseases. Drug delivery methods using natural and synthetic polymers are becoming increasingly common in the pharmaceutical industry, with biocompatible and bio-related copolymers and dendrimers having helped cure cancer as drug delivery systems. This review discusses all the above components and how, by combining synthetic and biological approaches, micro- and nano-drug delivery systems can result in revolutionary polymeric drug and gene delivery devices.

Highly positively charged poly(vinyl benzyl trimethylammonium chloride) (PVBMA) was successfully synthesized with approximately 82% of yield. The PVBMA was characterized by the molecular weight (Mw ) of 343.45 g mol-1 and the molecular weight distribution, (Đ) of 2.4 by 1 H NMR and SEC measurements. The PVBMA was applied as an effective agent for α-Al2 O3 surface modification in the adsorptive removal of the azo dye acid orange G (AOG). The AOG removal performance was significantly enhanced at all pH compared to without surface modification. The experimental parameters were optimal at pH 8, free ionic strength, 15 min of adsorption time, and 5 mg mL-1 α-Al2 O3 adsorbents. The AOG adsorption which was mainly controlled by the PVBMA-AOG electrostatic attractions was better applicable to the Langmuir isotherm and the pseudo-second kinetic model. The PVBMA-modified α-Al2 O3 demonstrates a high-performance and highly reusable adsorbent with great AOG performances of approximately 90.1% after 6 reused cycles.

It has been 100 years since the first article on polymerization was published by Hermann Staudinger [...].

Cationic random copolymers (PCm) consisting of 2-(methacryloyloxy)ethyl phosphorylcholine (MPC; P) with methacroylcholine chloride (MCC; C) and anionic random copolymers (PSn) consisting of MPC and potassium 3-(methacryloyloxy)propanesulfonate (MPS; S) were prepared via a reversible addition-fragmentation chain transfer method. "m" and "n" represent the compositions (mol %) of the MCC and MPS units in the copolymers, respectively. The degrees of polymerization for the copolymers were 93-99. Water-soluble MPC unit contains a pendant zwitterionic phosphorylcholine group whose charges are neutralized in pendant groups. MCC and MPS units contain the cationic quaternary ammonium and anionic sulfonate groups, respectively. The stoichiometrically charge-neutralized mixture of a matched pair of PCm and PSn aqueous solutions resulted in the spontaneous formation of water-soluble PCm/PSn polyion complex (PIC) micelles. These PIC micelles have the MPC-rich surface and MCC/MPS core. These PIC micelles were characterized using 1H NMR, dynamic and static light scattering, and transmission electron microscopic measurements. The hydrodynamic radius of these PIC micelles depends on the mixing ratio of the oppositely charged random copolymers. The charge-neutralized mixture formed maximum-size PIC micelles.

Solvent extraction has been ubiquitously used to recover valuable metals from wastes such as spent batteries and electrical boards. With increasing demands for energy transition, there is a critical need to improve the recycling rate of critical metals, including copper. Therefore, the sustainability of reagents is critical for the overall sustainability of the process. Yet, the recycling process relies on functional organic compounds based on the hydroxyoxime group. To date, hydroxyoxime extractants have been produced from petrol-based chemical feedstocks. Recently, natural-based cardanol has been used to produce an alternative hydroxyoxime. The natural-based oxime has been employed to recover valuable metals (Ga, Ni, Co) via a liquid/liquid extraction process. The natural compound has a distinctive structure with 15 carbons in the alkyl tail. In contrast, petrol-based hydroxyoximes have only 12 or fewer carbons. However, the molecular advantages of this natural-based compound over the current petrol-based ones remain unclear. In this study, molecular dynamics simulation was employed to investigate the effect of extractant hydrocarbon chains on the extraction of copper ions. Two hydroxyoxime extractants with 12 and 15 carbons in the alkyl chain were found to have similar interactions with Cu2+ ions. Yet, a slight molecular binding increase was observed when the carbon chain was increased. In addition, lengthening the carbon chain made the extracting stage easier and the stripping stage harder. The binding would result in a lower pH in the extraction step and a lower pH in the stripping step. The insights from this molecular study would help design the extraction circuit using natural-based hydroxyoxime extractants. A successful application of cashew-based cardanol will improve the environmental benefits of the recycling process. With cashew-producing regions in developing countries, the application also improves these regions' social and economic sustainability.

A laboratory-synthesized triblock copolymer poly(ethylene oxide-b-acrylic acid-b-styrene) (PEG-PAA-PS) was used as a template to synthesize hollow BaCO3 nanoparticles (BC-NPs). The triblock copolymer was synthesized using reversible addition-fragmentation chain transfer radical polymerization. The triblock copolymer has a molecular weight of 1.88 × 104 g/mol. Transmission electron microscopy measurements confirm the formation of spherical micelles with a PEG corona, PAA shell, and PS core in an aqueous solution. Furthermore, the dynamic light scattering experiment revealed the electrostatic interaction of Ba2+ ions with an anionic poly(acrylic acid) block of the micelles. The controlled precipitation of BaCO3 around spherical polymeric micelles followed by calcination allows for the synthesis of hollow BC-NPs with cavity diameters of 15 nm and a shell thickness of 5 nm. The encapsulation and release of methotrexate from hollow BC-NPs at pH 7.4 was studied. The cell viability experiments indicate the possibility of BC-NPs maintaining biocompatibility for a prolonged time.

Near-infrared (NIR)-triggered artificial meniscus climbing was realized using a shape memory polymer (SMP) object. The SMP was coated with polypyrrole (PPy) overlayer, which can convert NIR light into heat. The flat PPy-coated SMP became curved upon NIR irradiation owing to the photothermal conversion of PPy. The curved PPy-coated SMP demonstrated meniscus climbing.

Double hydrophilic diblock copolymers (DHBCs) with a zwitterionic block of poly[2-(methacryloyloxyethyl phosphorylcholine)] (PMPC) having degree of polymerization (DP) (n = 25) and other as thermo/pH-responsive poly[2-(dimethylaminoethyl methacrylate)] (PDMAEMA) block with DP (n = 24 and 48) abbreviated as PMPC25-b-PDMAEMAn were synthesized using reversible addition-fragmentation chain transfer (RAFT). The influence of the DP of the PDMAEMA block in both the DHBCs in different environments like pH, temperature, and salt concentration was studied exhaustively using proton nuclear magnetic resonance spectroscopy (1H-NMR) and gel-permeation chromatography (GPC). Additionally, the molecular interaction between the blocks was predicted from the optimized descriptors using a computational simulation framework. The self-assembly leading to successive micellization is examined from scattering techniques in the applied stimuli environment. The micellization was favored in alkaline pH and in the presence of salt, particularly for the DHBC with a high DP. Graphical Abstract: [Figure not available: see fulltext.]

We wish you all happiness, health and progress in the new year [...].

An amphiphilic diblock copolymer (PChM-PNIPAM), composed of poly(cholesteryl 6-methacryloyloxy hexanoate) (PChM) and poly(N-isopropyl acrylamide) (PNIPAM) blocks, was prepared via reversible addition-fragmentation chain transfer radical polymerization. The PChM and PNIPAM blocks exhibited liquid crystalline behavior and a lower critical solution temperature (LCST), respectively. PChM-PNIPAM formed water-soluble polymer micelles in water below the LCST because of hydrophobic interactions of the PChM blocks. The PChM and PNIPAM blocks formed the core and hydrophilic shell of the micelles, respectively. With increasing temperature, the molecular motion of the pendant cholesteryl groups increased, and a liquid crystalline phase transition occurred from an amorphous state in the core. With further increases in temperature, the PNIPAM block in the shell exhibited the LCST and dehydrated. Hydrophobic interactions of the PNIPAM shells resulted in inter-micellar aggregation above the LCST.

A series of amphiphilic diblock copolymers (PVAm-b-PVPin: AmPn = A82P6, A72P26, and A70P74) with different block lengths of hydrophilic poly(vinyl alcohol) (PVA, A) and hydrophobic poly(vinyl pivalate) (PVPi, P) blocks were prepared. AmPn was synthesized from a poly(vinyl acetate)-b-P (PVAc-b-P) diblock copolymer by selectively hydrolyzing the pendant acetyl groups in PVAc. In water, AmPn polymers formed spherical polymer micelles with a PVPi core and a PVA shell due to hydrophobic interactions between the PVPi blocks. The hydrodynamic radius (Rh), light scattering intensity (LSI), and aggregation number (Nagg) of AmPn increased with increasing PVPi block length. Conversely, the critical micelle concentration (CMC) was reduced due to stronger hydrophobic interactions. This study promotes potential applications for AmPn micelles to be used as nanocarriers for hydrophobic anticancer drugs.

We describe the synthesis of anticancer polymers containing hydrophobic groups. Cationic homopolymer does not show any anticancer activity on its own; however, the insertion of hydrophobic moieties synergistically enhances their anticancer activity.

Functionalizable poly(pentafluorophenyl methacrylate) (PPFPMA) and zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) are two polymers with an extremely different solubility. It is, therefore, almost impossible to synthesize their block copolymers in a controlled manner using a conventional approach. Herein, it is demonstrated, for the first time, that the synthesis and in situ formation of nanoassemblies of their diblock copolymers (PMPC-b-PPFPMA) can be achieved via polymerization-induced self-assembly using reversible addition-fragmentation chain-transfer dispersion polymerization in ethanol as a selective solvent. The PMPC was synthesized as the first block and further employed as a macro chain transfer agent (PMPC Macro-CTA) for the synthesis of the PPFPMA second block. In situ self-assembled nanostructures of the diblock copolymers were found to be mostly spherical with a varied degree of inter-micellar aggregation depending on the solid concentration and the relative length of the two blocks. Apparently, the limited chain mobility of the core-forming PPFPMA block, due to π-π stacking and hydrophobic interactions, hampered the formation of nanostructures of high-order morphologies. It is possible to perform core functionalization via post-polymerization modification with 1-pyrenemethylamine to yield fluorescently labeled nanostructures that may be applicable as biocompatible and non-fouling nanocarriers and nanosensors in the future.

Polyion complex (PIC) micelles were fabricated by directly mixing aqueous solutions of oppositely charged diblock copolymers, poly(2-(methacryloyloxy)ethylphosphorylcholine)-block-poly(vinylbenzyl trimethylammonium chloride) (PMPC-b-PVBTAC; P91V100) and PMPC-block-poly(sodium p-styrenesulfonate) (PMPC-b-PNaSS; P91N100). Cationic and anionic diblock copolymers were synthesized via controlled/living radical polymerization using the poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC) macrochain transfer agent. The subscript number represents the degree of polymerization (DP) of each block. A pair of oppositely charged diblock copolymers was mixed in an aqueous medium to prepare the PIC micelle using electrostatic, hydrophobic, and π–π interactions. The PIC micelles attained the maximum size and aggregation number when the charges of the cationic and anionic blocks were neutralized. The spherical core-shell micelle structure of the PIC micelle was confirmed. Generally, upon the addition of salt to the PIC micelle aqueous solution, the micelles dissociated because of the screening effect. However, the P91V100/P91N100 PIC micelle was stable against NaCl because the PVBTAC/PNaSS core of the PIC micelle was formed by electrostatic, hydrophobic, and π–π interactions. The P91V100/P91N100 PIC micelle can encapsulate charged and hydrophobic guest molecules.

Poly(4-((3-methacrylamidopropyl)dimethylammonium)butane-1-sulfonate) (PSBP) was prepared via controlled radical polymerization. PSBP showed upper critical solution temperature (UCST) behavior in aqueous solutions, which could be controlled by adjusting the polymer and NaCl concentrations. Owing to its pendant sulfonate anions, PSBP exhibited a negative zeta potential of -7.99 mV and formed a water-soluble ion complex with the cationic surfactant cetyltrimethylammonium bromide (CTAB) via attractive electrostatic interaction. A neutral PSBP/CTAB complex was formed under equimolar concentrations of the pendant sulfonate group in PSBP and the quaternary ammonium group in CTAB. Transmittance electron microscopic images revealed the spherical shape of the complex. The stoichiometrically neutral-charge PSBP/CTAB complex exhibited UCST behavior in aqueous solutions. Similar to PSBP, the phase transition temperature of the PSBP/CTAB complex could be tuned by modifying the polymer and NaCl concentrations. In 0.1 M aqueous solution, the PSBP/CTAB complex showed UCST behavior at a low complex concentration of 0.084 g/L, whereas PSBP did not exhibit UCST behavior at concentrations below 1.0 g/L. This observation suggests that the interaction between PSBP and CTAB in the complex was stronger than the interpolymer interaction of PSBP.

Effect of 1-butyl-3-methylimidazolium chloride ionic liquid ([bmim]Cl, IL) on the monolayer/bilayer of either soy-phosphatidylcholine (SPC) or hydrogenated soy-phosphatidylcholine (HSPC), in combination with 30 ​mol% cholesterol (Chol), were investigated. Impact of IL on monolayers were explored by measuring the surface pressure (π)-area (A) isotherm with a Langmuir-surface balance. Lift-off area (A0) of the monomolecular films gradually increased [A0(HSPC+IL) ​> ​A0(SPC+IL)], collapse pressures (πc) decreased and passed through minima [πc(HSPC+IL) ​> ​πc(SPC+IL)] with increasing IL concentration ([IL]). Minimum molecular area (Amin) increased monotonously and compression moduli (Cs−1) followed the sequence (HSPC+IL) ​> ​(SPC+IL) at a particular π with respect to [IL]. Dynamic light scattering studies were carried out to determine the hydrodynamic diameter (dh), zeta potential (Z.P.) and polydispersity index (PDI) values while fluorescence anisotropy studies, using 7-hydroxycoumarin and 1,6-diphenyl-1,3,5-hexatriene, could reveal the micro-viscosity of liposomes. Increased size and rigidity, induced by IL, suggest the formation of leak-proof, condensed liposomes. Disruption of vesicles induced by IL were observed from transmission electron microscopic (TEM) studies. IL induced disintegration of liposome and kinetics of subsequent formation of adsorbed monolayer were accomplished by surface pressure-time isotherms. IL-induced liposomes were substantially less toxic as revealed by MTT assay. These liposomes are considered to be safely used as effective and controlled drug delivery systems.

Polyion complex (PIC) micelles having a hydrodynamic radius of approximately 20 nm were prepared in water by simply mixing a pair of double hydrophilic oppositely charged diblock copolymers composed of a first block containing pendant phos-phobetaine groups and a second cationic or anionic styrene -based polyelectrolyte block. The PIC micelles were stable under high salt concentration because the formation of the PIC micelles was driven by both electrostatic and hydrophobic interactions.

There has been increasing interest in colloidal particles adsorbed at the air-water interface, which lead to stabilization of aqueous foams and liquid marbles. The wettability of the particles at the interface is known to play an important role in determining the type of air/water dispersed system. Foams are preferably formed using relatively hydrophilic particles, and liquid marbles tend to be formed using relatively hydrophobic particles. In this study, submicrometer-sized polystyrene particles carrying poly(N,N-diethylaminoethyl methacrylate) hairs (PDEA-PS particles), which are synthesized by dispersion polymerization, are demonstrated to work as a particulate stabilizer for both aqueous foams and liquid marbles. A key point for the hydrophilic PDEA-PS particles to stabilize both aqueous foams and liquid marbles, which have been generally stabilized with hydrophilic and hydrophobic particles, respectively, is the wetting mode of the particles with respect to water. The flocculates of PDEA-PS particles adsorb to the air-water interface from the aqueous phase to stabilize foam in a Wenzel mode, and the dried PDEA-PS particles adsorb to the interface as aggregates from the air phase to stabilize liquid marbles in a metastable Cassie-Baxter mode. On the basis of the difference in the wetting mode, stabilization of an air-in-water-in-air multiple gas-liquid dispersed system, named "foam marble", is realized. After the evaporation of water from the foam marble, a porous sphere is successfully obtained with pore sizes of a few tens of micrometers (reflecting the bubble sizes) and a few tens of nanometers (reflecting the gap sizes among the PDEA-PS particles).

A deep understanding of the effect of the ionic density in a polymer on the solution properties would contribute to the development of novel stimuli-responsive materials. To this end, a multibranched and highly dense structure is an attractive platform for the accumulation of ionizable groups. In this study, we focus on core-crosslinked multiarm star polymers having ionizable poly(acrylic acid) (PAA) segments in the arms with different sequences to evaluate the density effect of ionic segments on pH-responsive properties. Two types of star polymers with a PAA block on the outer or inner side of an arm chain in combination with a hydrophilic poly(2-hydroxyethyl acrylate) (PHEA) block were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. These star polymers exhibited aggregation behavior different from the corresponding linear block polymer in an acidic aqueous solution. Dynamic light scattering analysis in water revealed that the star polymer with PAA in the outer layer formed larger aggregates than the star polymer with the inverse layer structure, and the pH-responsive change of the hydrodynamic radius in water depends on the sequence in the arm polymers. This behavior resulted from the balance of hydrogen bonding between PAA and PHEA segments and PAA electrostatic repulsion.

A diblock copolymer (P(VBTAC/NaSS)17-b-PAPTAC50; P(VS)17A50) composed of amphoteric random copolymer, poly(vinylbenzyl trimethylammonium chloride-co-sodium p-styrensunfonate) (P(VBTAC/NaSS); P(VS)) and cationic poly(3-(acrylamidopropyl) trimethylammonium chloride) (PAPTAC; A) block, and poly(acrylic acid) (PAAc49 ) were prepared via a reversible addition−fragmentation chain transfer radical polymerization. Scrips V, S, and A represent VBTAC, NaSS, and PAPTAC blocks, respectively. Water-soluble polyion complex (PIC) vesicles were formed by mixing P(VS)17A50 and PAAc49 in water under basic conditions through electrostatic interactions between the cationic PAPTAC block and PAAc49 with the deprotonated pendant carboxylate anions. The PIC vesicle collapsed under an acidic medium because the pendant carboxylate anions in PAAc49 were protonated to delete the anionic charges. The PIC vesicle comprises an ionic PAPTAC/PAAc membrane coated with amphoteric random copolymer P(VS)17 shells. The PIC vesicle showed upper critical solution temperature (UCST) behavior in aqueous solutions because of the P(VS)17 shells. The pH-and thermo-responsive behavior of the PIC vesicle were studied using1H NMR, static and dynamic light scattering, and percent transmittance measurements. When the ratio of the oppositely charged polymers in PAPTAC/PAAc was equal, the size and light scattering intensity of the PIC vesicle reached maximum values. The hydrophilic guest molecules can be encapsulated into the PIC vesicle at the base medium and released under acidic conditions. It is expected that the PIC vesicles will be applied as a smart drug delivery system.

Poly(2-methoxyethyl acrylate) (PMEA) and poly(ethylene oxide) (PEO) have protein-antifouling properties and blood compatibility. ABA triblock copolymers (PMEAl-PEO11340-PMEAm (MEOMn; n is average value of l and m)) were prepared using single-electron transfer-living radical polymerization (SET-LRP) using a bifunctional PEO macroinitiator. Two types of MEOMn composed of PMEA blocks with degrees of polymerization (DP = n) of 85 and 777 were prepared using the same PEO macroinitiator. MEOMn formed flower micelles with a hydrophobic PMEA (A) core and hydrophilic PEO (B) loop shells in diluted water with a similar appearance to petals. The hydrodynamic radii of MEOM85 and MEOM777 were 151 and 108 nm, respectively. The PMEA block with a large DP formed a tightly packed core. The aggregation number (Nagg) of the PMEA block in a single flower micelle for MEOM85 and MEOM777 was 156 and 164, respectively, which were estimated using a light scattering technique. The critical micelle concentrations (CMCs) for MEOM85 and MEOM777 were 0.01 and 0.002 g/L, respectively, as determined by the light scattering intensity and fluorescence probe techniques. The size, Nagg, and CMC for MEOM85 and MEOM777 were almost the same independent of hydrophobic DP of the PMEA block.

Double-hydrophilic diblock copolymers, PMPC100-block-PGEMAn (M100Gn), were synthesized via reversible addition-fragmentation chain transfer radical polymerization using glycosyloxyethyl methacrylate and 2-(methacryloyloxy)ethyl phosphorylcholine. The degree of polymerization (DP) of the poly(2-(methacryloyloxy) ethylphosphorylcholine) (PMPC) block was 100, whereas the DPs (n) of the poly(glycosyloxyethyl methacrylate) PGEMA block were 18, 48, and 90. Water-soluble complexes of C70/M100Gn and fullerene (C70) were prepared by grinding M100Gn and C70 powders in a mortar and adding phosphate-buffered saline (PBS) solution. PMPC can form a water-soluble complex with hydrophobic C70 using the same method. Therefore, the C70/M100Gn complexes have a core-shell micelle-like particle structure possessing a C70/PMPC core and PGEMA shells. The maximum amounts of solubilization of C70 in PBS solutions using 2 g/L each of M100G18, M100G48, and M100G90 were 0.518, 0.358, and 0.257 g/L, respectively. The hydrodynamic radius (Rh) of C70/M100Gn in PBS solutions was 55-75 nm. Spherical aggregates with a similar size to the Rh were observed by transmission electron microscopy. When the C70/M100Gn PBS solutions were irradiated with visible light, singlet oxygen was generated from C70 in the core. It is expected that the C70/M100Gn complexes can be applied to photosensitizers for photodynamic therapy treatments.

Hydrophilic poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC) shows biocompatibility because the pendant phosphorylcholine group has the same chemical structure as the hydrophilic part of phospholipids that form cell membranes. Hollow particles can be used in various fields, such as a carrier in drug delivery systems because they can encapsulate hydrophilic drugs. In this study, vinyl group-decorated silica particles with a radius of 150 nm were covered with cross-linked PMPC based on the graft-through method. The radius of PMPC-coated silica particles increased compared to that of the original silica particles. The PMPC-coated silica particles were immersed in a hydrogen fluoride aqueous solution to remove template silica particles to prepare the hollow particles. The PMPC hollow particles were characterized by dynamic light scattering, infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy observations. The thickness of the hollow particle shell can be controlled by the polymerization solvent quality. When a poor solvent for PMPC was used for the polymerization, PMPC hollow particles with thick shells can be obtained. The PMPC hollow particles can encapsulate hydrophilic guest molecules by immersing the hollow particles in a high-concentration guest molecule solution. The biocompatible PMPC hollow particles can be used in a drug carrier.

The routine monitoring of direct oral anticoagulants (DOACs) may be considered in patients with renal impairment, patients who are heavily obese, or patients requiring elective surgery. Using the heparin-binding copolymer (HBC) and polybrene, we aimed to develop a solution for monitoring the anticoagulant activity of DOACs in human plasma in the interfering presence of unfractionated heparin (UFH) and enoxaparin. The thrombin time (TT) and anti-factor Xa activity were monitored in pooled plasma from healthy volunteers. In these tests, plasma with dabigatran or rivaroxaban was mixed with UFH or enoxaparin and then incubated with HBC or polybrene, respectively. HBC and polybrene neutralized heparins and enabled monitoring of anticoagulant activity of dabigatran in the TT test. Both agents allowed for accurate measurement of anti-factor Xa activity in the plasma containing rivaroxaban and heparins in the concentration range reached in patients’ blood. Here, we present diagnostic tools that may improve the control of anticoagulation by eliminating the contamination of blood samples with heparins and enabling the monitoring of DOACs’ activity.

Multi-stimuli-responsive materials may dominate next-generation drug delivery systems. Herein, dual-thermo-responsive micelles were prepared by introducing cholesterol chloroformate to facilitate the spontaneous self-assembly of graft polymers prepared by combining two charged polymers, poly-sulfobetaine and carboxylated ϵ-poly-l-lysine. This polymerization was controlled by reversible addition fragmentation chain transfer polymerization. Turbidimetry measurements and temperature-dependent 1H NMR spectroscopy were used to investigate the phase transition behaviors; transmission electron microscopy and atomic force microscopy were used to determine the morphology of the micelles. The dependence of self-assembled structures on temperature was investigated through ultra-small-angle X-ray scattering (USAXS). The micelles formed spherical shapes in water which was confirmed by TEM and AFM. Interestingly, different, temperature-dependent micelle size change behaviors were observed through dynamic light scattering, Ultraviolet-visible (UV-Vis) spectroscopy, and USAXS; this might be due to the concentration-dependent hierarchical phase transition. This study provides crucial information on the mesoscopic structure of the micelles, and will enable greater control over their transition temperatures for numerous biomaterial applications.

This review summarizes the development of pH-responsive polymers and their main applications. Random pH-responsive copolymers have been prepared via conventional free radical polymerization from a pH-responsive pendant fatty acid-containing monomer (AaU) and a permanent water-soluble pendant sulfonate-containing monomer (AMPS). In water, the resulting copolymers, P(A/AaU), form single polymer chain (unimer) micelles under acidic conditions due to intrapolymer hydrophobic interactions between the protonated AaU units. The surfaces of the unimer micelles are covered with hydrophilic AMPS units, which provide colloidal stabilization. Under basic conditions, the P(A/AaU) polymer chains expand as a result of the electrostatic repulsive interactions between the pendant ionized fatty acids and the sulfonate anions. Through the use of a pH-responsive AaU homopolymer, pH-responsive sunscreen was developed. Although pH-responsive sunscreen shows waterproof properties under neutral conditions, it disperses under weakly basic conditions such as soap water. Therefore, pH-responsive sunscreen resists sweat but can be washed off using soap water. pH-responsive diblock copolymers composed of a PAMPS block and a pH-responsive pendant fatty acid-containing block were prepared via controlled radical polymerization. In water, the block copolymers form interpolymer micelles under acidic conditions due to hydrophobic interactions between the protonated pendant fatty acid groups, whereas the polymer micelles dissociate under basic conditions. Finally, this review also discusses pH-responsive gelling agents based on ABA triblock copolymers.

Poly(2-methacryloyloxyethyl choline methylphosphonate) (PMCP) containing choline phosphonate groups, which consist of quaternary ammonium and anionic phosphonate groups in reverse order to that of phosphorylcholine, was synthesized via controlled radical polymerization. PMCP formed aggregates in water through electrostatic interactions. Meanwhile, poly(2- methacryloyloxyethyl phosphorylcholine) (PMPC) having a similar structure to that of PMCP was dissolved as a unimer in both water and salt solutions.

In this study, we investigated the morphology transition of polyion complex (PIC) micelles with the change in block ratio and pH-responsivity of PIC micelles or vesicles using entirely ionic diblock copolymers composed of carboxybetaine and ionic blocks. We used 2-((2-(methacryloylo-xy)ethyl)dimethylammonio)acetate (PGLBT) as carboxybetaine, poly(sodium styrenesulfonate) (PSSNa) as the anionic polymer, and poly[3-(methacrylamido)propyltrimethylammonium chlorid-e] (PMAPTAC) as the cationic polymer. The effect of pH on the PGLBT homopolymer and the PGLBT-containing diblock copolymer was examined by DLS, ELS, and transmittance, and a rapid change of state was observed between pH 4 and 2. At this pH, the carboxyl group of PGLBT was protonated to form a hydrogen bond in the molecule. Furthermore, at a lower pH, diblock copolymer behaved like a cationic polymer. The formation behavior of PIC micelles at different block ratios in the diblock copolymers was investigated by DLS, SLS, TEM, and AFM. PIC vesicles formed when the block ratio of ionic blocks to the PGLBT block was equal or larger (the content of PGLBT was 52% or less). On the other hand, PIC micelles were formed when the block ratio of PGLBT to ionic blocks was larger (the content of PGLBT was 68% or more). The pH-responsivity of PIC micelles was different from that of PIC vesicles. The size of PIC vesicles decreased by lowering pH and increased when the below pH 3. The behavior was the same as the change of state of PGLBT homopolymer with the change in pH. However, the size of PIC micelles increased by lowering pH from pH 6 to 3 and decreased at pH below pH 3. The PGLBT, which became the shell, changed its state with the change in pH and affected the aggregation number of micelles. Graphical Abstract: [Figure not available: see fulltext.]

The self-assembly of pH-responsive random and block copolymers composed of 2-(N,N-diisopropylamino)ethyl methacrylate and 2-methacryloyloxyethyl phosphorylcholine was investigated in aqueous media. Their pH-responsive behaviors were investigated in aqueous media by dynamic light scattering (DLS) and fluorescence measurements using a pyrene hydrophobic fluorescence probe. In an acidic environment, these copolymers existed as single polymer chains that did not interact with each other. In contrast, upon increasing the pH of the solution above the critical value of ~8, separated micelles were formed in the mixture, which was indicated by bimodal distribution in DLS results with radius of 4.5 and 10.4 nm, corresponding to the random and block copolymer micelles, respectively. Fluorescence resonance energy transfer efficiencies were near to zero in the mixture of the donor labeled block and acceptor labeled random copolymers under both acidic and basic pH. These results demonstrated the coexistence of two distinct micelles.

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A series of anionic homopolymers, poly(sodium 2-(acrylamido)-2-methyl-1-propanesulfonate) (PAMPS) and amphiphilic copolymers of AMPS and sodium 11-(acrylamido)undecanoate (AaU), both block (PAMPS75-b-PAaUn), and random (P(AMPSm-co-AaUn)), were synthesized and their antiviral activity against Zika virus (ZIKV) was evaluated. Interestingly, while the homopolymers showed limited antiviral activity, the copolymers are very efficient antivirals. This observation was explained considering that under the conditions relevant to the biological experiments (pH 7.4 PBS buffer) the macromolecules of these copolymers exist as negatively charged (zeta potential about −25 mV) nanoparticles (4–12 nm) due to their selforganization. They inhibit the ZIKV replication cycle by binding to the cell surface and thereby blocking virus attachment to host cells. Considering good solubility in aqueous media, low toxicity, and high selectivity index (SI) of the PAMPS-b-PAaU copolymers, they can be considered promising agents against ZIKV infections.

Polymer vesicles (polymersomes) have received considerable attention in the last several decades, but little has been known about the kinetics of the formation process, despite their importance both scientifically and in practical applications. Here, we reported the formation kinetics of polymer vesicles in aqueous NaCl solutions of anionic-neutral and cationic-neutral block copolymers when they transform from micelles with a polyelectrolyte complex core. Vesicle formation from spherical or cylindrical micelles was initiated by fast mixing with a stopped-flow device. We then employed time-resolved ultrasmall-angle X-ray scattering with millisecond resolution, which enabled monitoring the kinetic process of vesicle formation. An in-depth analysis of the scattering data elucidated the following processes: in the case that the initial state was spherical micelles, they grew with time to form short cylindrical micelles. These short cylindrical micelles then transformed into disklike micelles, which subsequently closed to form vesicles. On the other hand, when the initial state involved cylindrical micelles, the disklike micelles similarly assembled, which then transformed into vesicles. The bilayer membrane of vesicles used in this study was 4 times thicker than that of vesicles formed from conventional low-molecular-weight surfactants; hence, the bending rigidity of the bilayer was approximately 16 times higher. Due to this feature, the kinetic process was different from that of conventional low-molecular-weight surfactants, in particular, an increase in the size of the disklike micelles was not observed. Instead, the weight fraction of the disklike micelles gradually decreased, and concomitantly, the weight fraction of vesicles increased since the larger transient disklike micelles or bowl-like micelles were unstable. This behavior could be well reproduced by our proposed kinetic model. This is the first report on the self-assembly kinetics of polymer vesicles probed by time-resolved small-angle scattering.

A triblock copolymer (PEG-b-PUEM-b-PMPC; EUM) comprising poly(ethylene glycol) (PEG), thermo-responsive poly(2-ureidoethyl methacrylate) (PUEM), and poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC) blocks was synthesized via controlled radical polymerization. PEG and PMPC blocks exhibit hydrophilicity and biocompatibility. The PUEM block exhibits an upper critical solution temperature (UCST). PMPC can dissolve hydrophobic fullerenes in water to form a complex by grinding PMPC and fullerene powders. Fullerene-C70 (C70) and EUM were ground in a mortar and phosphate-buffered saline (PBS) was added to synthesize a water-soluble complex (C70/EUM). C70/EUM has a core-shell-corona structure, whose core is a complex of C70 and PMPC, the shell is PUEM, and corona is PEG. The maximum C70 concentration dissolved in PBS was 0.313 g L−1 at an EUM concentration of 2 g L−1. The C70/EUM hydrodynamic radius (Rh) was 34 nm in PBS at 10 °C, which increased due to the PUEM block's UCST phase transition with increasing temperature, and Rh attained a constant value of 38 nm above 36 °C. An anticancer drug, doxorubicin, was encapsulated in the PUEM shell by hydrophobic interactions in C70/EUM at room temperature, which can be released by heating. The generation of singlet oxygen (1O2) from C70/EUM upon visible-light irradiation was confirmed using the singlet oxygen sensor green indicator. Water-soluble C70/EUM may be used as a carrier that releases encapsulated drugs when heated and as a photosensitizer for photodynamic therapy.

Uncontrolled bleeding after enoxaparin (ENX) is rare but may be life-threatening. The only registered antidote for ENX, protamine sulfate (PS), has 60% efficacy and can cause severe adverse side effects. We developed a diblock copolymer, heparin-binding copolymer (HBC), that reverses intravenously administered heparins. Here, we focused on the HBC inhibitory activity against subcutaneously administered ENX in healthy mice. BALB/c mice were subcutaneously injected with ENX at the dose of 5 mg/kg. After 110 min, vehicle, HBC (6.25 and 12.5 mg/kg), or PS (5 and 10 mg/kg) were administered into the tail vein. The blood was collected after 3, 10, 60, 120, 360, and 600 min after vehicle, HBC, or PS administration. The activities of antifactors Xa and IIa and biochemical parameters were measured. The main organs were collected for histological analysis. HBC at the lower dose reversed the effect of ENX on antifactor Xa activity for 10 min after antidote administration, whereas at the higher dose, HBC reversed the effect on antifactor Xa activity throughout the course of the experiment. Both doses of HBC completely reversed the effect of ENX on antifactor IIa activity. PS did not reverse antifactor Xa activity and partially reversed antifactor IIa activity. HBC modulated biochemical parameters. Histopathological analysis showed changes in the liver, lungs, and spleen of mice treated with HBC and in the lungs and heart of mice treated with PS. HBC administered in an appropriate dose might be an efficient substitute for PS to reverse significantly increased anticoagulant activity that may be connected with major bleeding in patients receiving ENX subcutaneously.

Stimuli-responsive di-block copolymers viz. poly(N-isopropylacrylamide)m-block-poly(butyl-3-vinylimidazolium bromide)n [abbreviated as PNIPAMm-b-PBVIBn m = 50 and 100, n = 54 and 115] were synthesized using RAFT (Reversible addition−fragmentation chain-transfer) polymerization. Gel permeation chromatography (GPC) and nuclear magnetic resonance (1H NMR) spectroscopy were used to characterize the block copolymer. Turbidity data shows that the lower critical solution temperature (LCST) of PNIPAM is independent of the molecular weight. No LCST behavior was estimated for PBVIB58 in an aqueous media. The addition of 2.75 M NaCl brings LCST of PBVIB58 to room temperature. The cloud point temperature (CPT) of both the block copolymers increases with an increase in the degree of polymerization of PBVIB. Scattering techniques confirm the molecular state of all the homopolymers at 28 °C in the dissolved condition. With an increase in temperature and the presence of sodium chloride (NaCl), both the copolymers remain as aggregates with PNIPAM as a core and PBVIB as a shell. The reverse structure is formed via the addition of 10 mM sodium dodecyl sulfate (SDS) into PNIPAM100-b-PBVIB54 solution.

Physicochemical properties of lipid monolayer depend on its composition where a blend of lipids exhibit superior behaviour than the individual component. Surface pressure (π) – area (A) isotherms of mixed monolayer (PCmix) formed by dipalmitoylphosphatidylcholine (DPPC), palmitoleylphosphatidylcholine (POPC), soyphosphatidylcholine (SPC) and hydrogenated soy phosphatidylcholine (HSPC) in combination with 30 mole % cholesterol (Chol) were obtained by using Langmuir trough. Effects of dipalmitoylphosphatidyethanolamine (DPPE) on its mutual miscibility at the air-water interface with DPPC ​+ ​Chol, POPC ​+ ​Chol, HSPC ​+ ​Chol and SPC ​+ ​Chol were also investigated separately, followed by studying the effects of DPPE and dipalmitoylphosphatidylglycerol (DPPG) to PCmix ​+ ​Chol and PCmix ​+ ​DPPE ​+ ​Chol respectively. Lift-off area, minimum molecular area, excess molecular area, collapse pressure, Gibbs free energy of interfacial mixing, compressibility modulii values were evaluated by analyzing the isotherms. Deviations from the ideal mixing behaviours were dependent on the composition of the lipid blends. Surface dilatational rheology studies could assess monolayer elasticity, whereas the film morphologies were analysed by Brewster angle microscopic (BAM) studies. DPPC induced formation of condensed monolayer, whereas film rigidity was increased with the incorporation of DPPE and DPPG into mixed systems. Interactions among the lipid components of the investigated mixed systems were thoroughly discussed from the point of view of polar head and acyl chain saturation and obtained results follow the sequence: PCmix ​+ ​DPPE ​+ ​DPPG ​+ ​Chol ​> ​PCmix ​+ ​DPPE ​+ ​Chol ​> ​individual PC ​+ ​DPPE ​+ ​Chol which could be translated into the bilayer studies. Such investigation of mixed lipid is important for class of its own composition and combined results are expected to contribute in better understanding the interaction of selected lipid in proposed blend.

We report the first study of adsorption of a strong polycation, poly(3-methacryloylamino propyl-trimethylammonium chloride) (PMAPTAC) on nanosilica (nano-SiO2) extracted from rice husk. PMAPTAC was successfully synthesized and characterized by 1H-nuclear magnetic resonance (1H NMR) and gel-permeation chromatography (GPC) methods. PMAPTAC characteristics were found to be Mn = 1.61 × 105, Mw = 2.16 × 106, Mw/Mn = 13.4. Beta-lactam cefixime (CEF) removal was dramatically enhanced after polymer coating by pre-adsorption of PMAPTAC on nano-SiO2. The new adsorbent was dubbed PMAPTAC coated nano-SiO2 (PCNS). Required time for adsorption, PCNS dosage, pH, and KCl concentration were thoroughly optimized for CEF removal and achieved at 120 min, 10 mg/mL, 4, and 1 mM, respectively. A two-step model can be used to fit the PMAPTAC on nano-SiO2 and CEF on PCNS isotherms at different ionic strengths. Adsorption kinetics of CEF on PCNS appears to be pseudo-second-order. CEF removal using PCNS reached 89%, saturating at 10.9 mg/g. The driving force for CEF adsorption on PCNS was primarily Coulombic interaction of negative CEF species and positive surface charge of PCNS. After three reuses, CEF elimination was still greater than 85%. The influence of some organics on CEF treatment using PCNS was insignificant while CEF removal from a real hospital wastewater sample was greater than 70%. Our study indicates that a hybrid and new adsorbent based on nano-SiO2 rice husk with pre-adsorption with PMAPTAC is useful for antibiotic removal from wastewater.

The combination of polymerization-induced self-assembly (PISA) and post-polymerization modification is a versatile route to prepare core-functionalized nanoaggregates. PISA is a useful approach for preparingin situself-assembled nano-objects, in which morphological nanostructures are tunable with a high solid concentration that can afford scale-up syntheses. Herein, the preparationviaPISA of diblock copolymers that have functional groups in their structures to be further post-functionalized using active modifiers has been reviewed. The resulting multifunctional nanoaggregates exhibit great potential for use in a wide range of applications, for example, crosslinked nano-objects having improved stability, stimuli responsive vehicles for drug delivery, and fluorescent nanomaterials for bioimaging.

Amphiphilic diblock copolymers (M98En) composed of hydrophilic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC, M) and hydrophobic poly(2-methoxyethyl acrylate) (PMEA, E) were prepared via controlled radical polymerization. The degree of polymerization (DP) of the PMPC block was 98, and the DP values of the PMEA block (=n) were 95 and 314. In water, M98En formed micelles with hydrophobic PMEA cores and hydrophilic PMPC shells. The size, density, and aggregation number of M98E314 were larger than those of M98E95 because the hydrophobic interactions became stronger with increasing PMEA block length. A hydrophobic anticancer agent, i.e., doxorubicin, was encapsulated into the core of the polymer micelles to assess the potential of these micelles as carriers in a drug delivery system. Micelles formed from M98En did not interact with proteins in the aqueous solution because the micelle surfaces were covered with biocompatible PMPC shells.

Liquid marble (LM) can be prepared by the adsorption of hydrophobic powder on the gasliquid interface of a water droplet. Generally, LM is prepared using hydrophobic powder with a size of >100 nm. LM is opaque and the inside of LMs cannot be observed because the surface powder adsorbs and scatters the visible light. In this study, a pH-responsive clear LM (CLM) is prepared using tertiary amino groups containing hydrophobic silica particles with a diameter of ~20 nm. The shape of CLM changed under acidic conditions, because the tertiary amino groups on the silica particles became hydrophilic under these conditions.