Compound Vesicles Research Articles

Preparation of diblock copolymer nano-assemblies by ultrasonics assisted ethanol-phase polymerization-induced self-assembly

Assemblies are widely used in biomedicine, batteries, functional coatings, Pickering emulsifiers, hydrogels, and luminescent materials. Polymerization-induced self-assembly (PISA) is a method for efficiently preparing particles, mainly initiated thermally. However, thermally initiated PISA usually requires a significant amount of time and energy. Here, we demonstrate the preparation of nano-assemblies with controllable morphologies and size using ultrasound (20 kHz) assisted ethanol-phase RAFT-PISA in three hours. Using poly (N, N-dimethylaminoethyl methacrylate) as the macromolecular reversible addition-fragmentation chain transfer agent (PDMA-CTA) to control the nucleating monomer benzyl methacrylate (BzMA), we obtained nano-assemblies with different morphologies. With the length of hydrophobic PBzMA block growth, the morphologies of the assemblies at 15 wt% solid content changed from spheres to vesicles, and finally to lamellae; the morphologies of the assemblies at 30 wt% changed from spheres micelles to short worms, then vesicles, and finally to large compound vesicles. With the same targeted degree of polymerization, nano-assemblies having a 30 wt% solid content display a more evolved morphology. The input of ultrasonic energy makes the system have higher surface free energy, results the mass fraction interval of solventphilic blocks (fhydrophilic) corresponding to the formation of spherical micelles is expanded from fhydrophilic > 45 % to fhydrophilic > 31 % under ultrasound and the fhydrophilic required to form worms, vesicles, and large composite vesicles decreases in turn. It is worth noting that the fhydrophilic interval of worms prepared by ultrasonics assisted PISA gets larger. Overall, the highly green, externally-regulatable and fast method of ultrasonics assisted PISA can be extended to vastly different diblock copolymers, for a wide range of applications.

Combined Core Stability and Degradability of Nanomedicine via Amorphous PDLLA-Dextran Bottlebrush Copolymer for Alzheimer's Disease Combination Treatment.

Nanomedicine faces the challenges of infinite dilution, shear force, biological protein, or electrolyte competition. However, core cross-linking leads to biodegradability deficiency and brings inevitable side effects of nanomedicine on normal tissues. In order to overcome this bottleneck problem, we turn to amorphous poly(d,l)lactic acid (PDLLA)-dextran bottlebrush to emphasize the core stability of nanoparticles, and the amorphous structure offers an additional advantage of fast degradation property over the crystalline PLLA polymer. The graft density and side chain length of amorphous PDLLA together played important influence roles in controlling the architecture of nanoparticles. This effort produces structure-abundant particles, including micelles, vesicles, and large compound vesicles after self-assembly. Here, the amorphous bottlebrush PDLLA was verified to play a beneficial role in the structure stability and degradability of nanomedicines. The codelivery of the hydrophilic antioxidant of citric acid (CA), vitamin C (VC), and gallic acid (GA) via the optimum nanomedicines could effectively repair the SH-SY5Y cell damage caused by H2O2. The CA/VC/GA combination treatment repaired the neuronal function efficiently, and the cognitive abilities of senescence-accelerated mouse prone 8 (SAMP8) recovered.

Degradable polymeric nanomaterials with a high solid content and multiple morphologies by polymerization-induced self-assembly.

The preparation of degradable polymeric nanomaterials with a high solid content and multiple morphologies is highly desirable but still challenging. Here, the RAFT dispersion polymerization of styrene and 5,6-benzo-2-methylene-1,3-dioxepane was demonstrated to achieve various morphologies, including spheres, vesicles, worms, and large compound vesicles, with a high solid content through polymerization-induced self-assembly, which opens up a new avenue for the preparation of degradable polymeric nanomaterials.

Structural Engineering in the Self-Assembly of Amphiphilic Block Copolymers with Reactive Additives: Micelles, Vesicles, and Beyond.

Control of polymer assemblies in solution is of great importance to determine the properties and applications of these polymer nanostructures. We report a novel co-self-assembly strategy to control the self-assembly outcomes of a micelle-forming amphiphilic block copolymer (BCP) of poly(ethylene oxide) (PEO) and poly[3-(trimethoxysilyl)propyl methacrylate] (PTMSPMA), PEO114-b-PTMSPMA228. With a reactive and hydrophobic additive tetraethyl orthosilicate (TEOS), the assembly nanostructures of PEO114-b-PTMSPMA228 are tunable. The swelling of the PTMSPMA block by hydrophobic TEOS increases the hydrophobic-to-hydrophilic ratio that enables a continuous morphological evolution from spherical micelles to vesicles and eventually to large compound vesicles. TEOS that co-hydrolyzes with the PTMSPMA block can further stabilize and fix these hybrid nanostructures. With high TEOS concentrations, these polymer assemblies can be further converted through thermal annealing into unique silica nanomaterials, including nanospheres, hollow nanoparticles with dual shells, and mesoporous silica frameworks that cannot be synthesized through conventional syntheses otherwise.

Two new species of the genus Psyllaphorura/ (Collembola: Onychiuridae) from the east of European Russia.

Two new species of the genus Psyllaphorura Bagnall, 1948, namely P. silvestris sp. nov. and P. pseudopodis sp. nov., are described from the European Russia. The former species can be compared to the Nearctic P. obesa (Mills, 1934) which has almost the same number of dorsal pseudocelli, but differs in having compound vesicles in PAO. Psyllaphorura pseudopodis sp. nov. is similar to P. altaica Weiner, Stebaeva Kaprus', 2019 recently described from the Altai Mountains, southern Siberia. Both these species have the same number and arrangement of the cephalic pseudocelli. Nonetheless, P. pseudopodis sp. nov. can be distinguished by the absence of pseudocelli on Abd. IV, only 2+2 dental setae and a shorter unguiculus. Besides this, P. pseudopodis sp. nov. is unique in the presence of a pair of ventral swellings on the fourth abdominal segment. Based on a revision of the types, P. sensillifera (Martynova, 1981) is considered a senior synonym of P. raoheensis Sun Wu, 2013. Taxonomic notes on the most important diagnostic characters of the genus are given, as well as a key and a table summarizing these characters in all Psyllaphorura species known in the World so far.

Two new species of the tribe Hymenaphorurini Pomorski, 1996 (Collembola: Onychiuridae) from Korea

• Two new species of family Onychiuridae are discovered in Korea. • Description with illustrations of the new species are presented. • Table to major characters of the genus Psyllaphorura are provided. Two new species, Heteraphorura koreana sp. nov. and Psyllaphorura jirisana sp. nov. , of the tribe Hymenaphorurini are described and illustrated based on materials from South Korea. Heteraphorura koreana sp. nov. belongs to the oriental species-group of the genus Heteraphorura , because of compound vesicles in the postantennal organ. This new species shares the same number of PAO with Heteraphorura pseudoseolagensis ( Martynova, 1981 ) from Russia, but differs in pso dorsal formula and lateral teeth of claw. Psyllaphorura jirisana sp. nov. is similar to Psyllaphorura sensillifera. (Martynova, 1981) from the Russian Far East, but can be distinguished by shape of vesicles in PAO, dorsal s-chaetae on head and ratio AS/unguis. www.zoobank.org/urn:lsid:zoobank.org:pub:F854CBFD-06D0-4396-B8D9-62468B427111 .

Self-Assembly of Linear Amphiphilic Pentablock Terpolymer PAAx-PS48-PEO46-PS48-PAAxin Dilute Aqueous Solution.

A series of linear amphiphilic pentablock terpolymer PAAx-b-PS48-b-PEO46-b-PS48-b-PAAx (AxS48O46S48Ax) with various lengths x of the PAA block (x = 15, 40, 60, and 90) were synthesized via a two-step atom transfer radical polymerization (ATRP) using Br-poly(ethylene oxide)-Br (Br-PEO46-Br) as the macroinitiator, styrene (St) as the first monomer, and tert-butyl acrylate (tBA) as the second monomer, followed with the hydrolysis of PtBA blocks. The AxS48O46S48Ax pentablock terpolymers formed micelles in dilute aqueous solution, of which the morphologies were dependent on the length x of the PAA block. Cryogenic transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS), and zeta potential measurement were employed to investigate the morphologies, chain structures, size, and size distribution of the obtained micelles. The morphology of AxS48O46S48Ax micelles changed from spherical vesicles with ordered porous membranes to long double nanotubes, then to long nanotubes with inner modulated nanotubes or short nanotubes, and finally, to spherical micelles or large compound vesicles with spherical micelles inside when x increased from 15 to 90. The hydrophobic PS blocks formed the walls of vesicles and nanotubes as well as the core of spherical micelles. The hydrophilic PEO and PAA block chains were located on the surfaces of vesicle membranes, nanotubes, and spherical micelles. The PAA block chains were partially ionized, leading to the negative zeta potential of AxS48O46S48Ax micelles in dilute aqueous solutions.

Polymerization-Induced Self-Assembly for the Synthesis of Poly(N,N-dimethylacrylamide)-b-Poly(4-tert-butoxystyrene) Particles with Inverse Bicontinuous Phases.

Polymerization-induced self-assembly (PISA) has been routinely used to produce block copolymer (BCP) particles with various morphologies, but inverse bicontinuous phases have remained scarce. Herein, PISA preparation of poly(N,N-dimethylacrylamide-b-poly(4-tert-butoxystyrene) (PDMA-b-PtBOS) BCP particles with inverse bicontinuous phases in ethanol/water at 30% w/v solid content is reported. The effect of solvent composition and degree of polymerization of the core-forming PtBOS block is investigated. tBOS monomer conversion is enhanced on increasing water content, and inverse bicontinuous phases are effectively produced using a short PDMA stabilizer block. Morphology studies by both transmission and scanning electron microscopies reveal that transitions from vesicles to compound vesicles to inverse bicontinuous phases are the key mechanistic steps toward the formation of (partially) ordered mesophases.

Nonequilibrium Reshaping of Polymersomes via Polymer Addition.

Polymersomes are a class of artificial liposomes, assembled from amphiphilic synthetic block copolymers, holding great promise toward applications in nanomedicine. The diversity in polymersome morphological shapes and, in particular, the precise control of these shapes, which is an important aspect in drug delivery studies, remains a great challenge. This is due to a lack of general methodologies that can be applied and the inability to capture the morphologies at the nanometer scale. Here, we present a methodology that can accurately control the shape of polymersomes via the addition of polyethylene glycol (PEG) under nonequilibrium conditions. Various shapes including spheres, ellipsoids, tubes, discs, stomatocytes, nests, stomatocyte-in-stomatocytes, disc-in-discs, and large compound vesicles (LCVs) can be uniformly captured by adjusting the water content and the PEG concentration. Moreover, these shapes undergo nonequilibrium changes in time, which is reflected in their phase diagram changes. This research provides a universal tool to fabricate all shapes of polymersomes by controlling three variables: water content, PEG concentration, and time. The use of the biofriendly polymer PEG enables the application of this methodology in the field of nanomedicine.

Extraction-Induced Fabrication of Yolk–Shell-Structured Nanoparticles with Deformable Micellar Cores and Mesoporous Silica Shells for Multidrug Delivery

Yolk-shell-structured nanoparticles (YSNs) provide useful carriers for applications in biomedicine and catalysis due to the excellent loading capability and versatile functionality of the flexible core and porous shell. Unfortunately, the reported YSNs always require complex multistep synthesis processes and a harsh hard-template etching strategy. Herein, a facile "selective extraction" strategy is developed to synthesize yolk-shell-structured polymer@void@mSiO2 nanoparticles (designated as YSPNs) comprising deformable and soft polystyrene-b-poly(acrylic acid) (PS-b-PAA) micellar cores and mesoporous silica shells. The YSPNs are formed by a morphological change and volume shrinkage of the PS-b-PAA aggregates from large compound vesicles to large compound micelles during the extraction process. As a multidrug vehicle, both hydrophobic curcumin (Cur, 6.4 wt %) and hydrophilic doxorubicin hydrochloride (Dox, 19.4 wt %) can be coloaded onto YSPNs through a successive impregnation method. Moreover, the resulting Cur/Dox@YSPNs possess intelligent pH-responsive capability, time-sequenced release behavior, and high in vivo antitumor efficiency, demonstrating excellent potential as safe and efficient multidrug nanocarriers for tumor chemotherapy. We envision that such a facile "selective extraction" strategy will enable pathways to construct organic-inorganic hybrid nanoparticles with yolk-shell structures for various applications.

Tailoring Polymersome Shape Using the Hofmeister Effect.

Reshaping polymersomes remains a challenge for both size and shape control, methodology development, and mechanism understanding, which hindered their application in nanomedicine and nanomachine. Unlike liposome, polymersomes are capable of maintaining their shape due to their rigid and glassy membrane. Here we use the Hofmeister effect to guide the shape control of polymersome by tuning the ion type and concentration. Multiple morphologies such as ellipsoid, tube, disc, stomatocytes, and large compound vesicles are found. These results give evidence of demonstrating that the shape changes are not only induced by osmotic pressure, but also by the interaction with the polymersome membranes. Additionally, this methodology provides a general tool to tailor the shape of polymersome into various morphologies.

Electrostatic Interaction Mediates the Formation of Vesicular Structures from Coassembly of PS-b-PAA with Quantum Dots.

Vesicular structures of block copolymers and inorganic nanoparticles with good stability have potential applications in therapeutic drug release and bioimaging. Herein, a block copolymer of polystyrene-b-poly(acrylic acid) (PS48-b-PAA67) and water-soluble AgInS2/ZnS core/shell quantum dots (QDs) capped with gelatin and thioglycolic acid were coassembled in tetrahydrofuran by adding water. The positively charged QDs bind to negatively charged PAA segments through electrostatic interaction. Numerous vesicular structures, such as uniform bilayer vesicles, flowerlike large compound vesicles, onionlike lamellar structures consisting of alternating PS and PAA&QD layers, and multilamellar vesicles with spaces between concentric vesicle layers were obtained from the coassembly of PS48-b-PAA67 with QDs. The binding of the positively charged QDs to the PAA block influenced both the intra-aggregate PAA corona conformation and the interaggregate interactions. The key parameters affecting the formation of these vesicular structures included the QD content, solution pH, and water addition rate. Thus, tunable vesicular structures can be prepared and regulated through this simple but effective coassembly method.

Block copolymer vesicles via liquid/liquid interface-mediated self-assembly

Self-assembly behavior of amphiphilic block copolymers has attracted much attention recently. In this paper, a novel liquid/liquid interface-mediated self-assembly behavior of block copolymer is reported. An aqueous solution of HAuCl4 and a chloroform solution of poly(2-vinylpyridine)-block-polycaprolactone (P2VP199-b-PCL22) are employed as the upper phase and the bottom phase, respectively. Structural transitions from toroids and plate like structures to vesicles and large compound vesicles are observed in the bottom phase by using transmission electron microscopy (TEM). It is proved that vesicles and large compound vesicles are formed through adsorption and desorption of copolymers at the liquid/liquid interface, molecular aggregation and microphase separation in the bottom phase due to the amphiphilic property of protonated P2VP199-b-PCL22. The well-dispersed Au nanoparticles are formed during the self-assembly process and embedded in the bilayers of the vesicles. The concentrations of HAuCl4 and P2VP199-b-PCL22 have an effect on the self-assembly behavior. A unique structure, “pearl necklace”, is obtained at higher concentrations. In addition, it was found that P2VP252-b-PCL44 also formed vesicles, while P2VP195-b-PCL75 and P2VP195-b-PCL307 formed spherical micelles in the bottom phase through the same approach. The dependence of the aggregate morphology and the molecular structure was discussed based on the critical packing parameter, p.

Overcoming Kinetic Trapping for Morphology Evolution during Polymerization‐Induced Self‐Assembly

Polymerization-induced self-assembly (PISA) is a powerful technique to synthesize assemblies with various morphologies. However, PISA mediated by long, stabilizing chains usually produces kinetically trapped spheres; thus, the morphology evolution remains a challenge. Here, a convenient and general strategy for facilitating the morphological evolution by the copolymerization of solvophilic monomers is reported. With the incorporation of only 7% (molar ratio) solvophilic 3-(triethoxysilyl)propyl methacrylate (TESPMA) into poly(N,N-dimethylaminoethyl methacrylate)-b-poly(benzyl methacrylate) (PDMA-b-PBzMA) spheres, PDMA-b-P(BzMA-co-TESPMA) assemblies evolve from spheres to worms, octopi-like and jellyfish-like structures, vesicles, and large compound vesicles. This non-specific effect is further confirmed by the copolymerization of BzMA with other solvophilic monomers, including N,N-dimethylaminoethyl methacrylate (DMA), N,N-diethylaminoethyl methacrylate (DEA), and 2-hydroxypropyl methacrylate (HPMA). This work provides a convenient approach to promote morphology evolution and develops the formulations design of PISA.

Exceptional Multi Stage Mineralization of Secondary Minerals in Cavities of Flood Basalts from the Deccan Volcanic Province, India

Flood basalts of the Deccan Volcanic Province erupted between about 67.5 to 60.5 Ma ago and reached a thickness of up to 3500 m. The main part consists of compound and simple lava flows with a tholeiitic composition erupted within 500,000 years at about 65 Ma. Within the compound lava flows, vesicles and cavities are frequent. They are filled by secondary minerals partly of well development and large size. This study presents data on the secondary mineralization including detailed field descriptions, optical, cathodoluminescence and SEM microscopy, X-ray diffractometry, fluid inclusions, C and O isotope analyses, and Rb-Sr and K-Ar geochronology. The investigations indicate a multistage precipitation sequence with three main stages. During stage I clay minerals and subsurface filamentous fabrics (SFFs), of probably biogenic origin, formed after the lava flows cooled down near to the Earth’s surface. In stage II, first an assemblage of calcite (I) and zeolite (I) (including mordenite, heulandite, and stilbite) as well as plagioclase was overgrown by chalcedony, and finally a second calcite (II) and zeolite (II) generation developed by burial metamorphism by subsequent lava flows. Stage III is characterized by precipitation of a third calcite (III) generation together with powellite and apophyllite from late hydrothermal fluids. Rb-Sr and K-Ar ages of apophyllite indicate a large time span for stage III. Apophyllite formed within different time intervals from the Paleogene to the early Miocene even within individual lava flows at certain localities. From the Savda/Jalgaon quarry complex, ages cluster at 44–48 Ma and 25–28 Ma, whereas those from the Nashik area are 55–58 Ma and 21–23 Ma, respectively.

A theoretical study on the dynamics of a compound vesicle in shear flow.

The dynamics of nucleate cells in shear flow is of great relevance in cancer cells and circulatory tumor cells where they determine the flow properties of blood. Buoyed by the success of giant unilamellar vesicles in explaining the dynamics of anucleate cells such as red blood cells, compound vesicles have been suggested as a simple model for nucleate cells. A compound vesicle consists of two concentric unilamellar vesicles with the inner, annular and outer regions filled with aqueous Newtonian solvents. In this work, a theoretical model is presented to study the deformation and dynamics of a compound vesicle in linear shear flow using small deformation theory and spherical harmonics with higher order approximation to the membrane forces. A coupling of viscous and membrane stresses at the membrane interface of the two vesicles results in highly nonlinear shape evolution equations for the inner and the outer vesicles which are solved numerically. The results indicate that the size of the inner vesicle (χ) does not affect the tank-treading dynamics of the outer vesicle. The inner vesicle admits a greater inclination angle than the outer vesicle. However, the transition to trembling/swinging and tumbling is significantly affected. The inner and outer vesicles exhibit identical dynamics in the parameter space defined by the nondimensional rotational (Λan) and extensional (S) strength of the general shear flow. At moderate χ, a swinging mode is observed for the inner vesicle while the outer vesicle exhibits tumbling. The inner vesicle also exhibits modification of the TU mode to IUS (intermediate tumbling swinging) mode. Moreover, synchronization of the two vesicles at higher χ and a Capillary number sensitive motion at lower χ is observed in the tumbling regime. These results are in accordance with the few experimental observations reported by Levant and Steinberg. A reduction in the inclination angle is observed with an increase in χ when the inner vesicle is replaced by a solid inclusion. Additionally, a very elaborate phase diagram is presented in the Λan-S parameter space, which could be tested in future experiments or numerical simulations.

Versatile preparation of vesicle from amphiphilic bottlebrush block copolymers

Polymeric vesicles show vast potential in drug delivery for the treatments of various diseases. In this work, we report here an advanced polymeric vesicle formed by amphiphilic bottlebrush block copolymers (BBCPs), which have a large size and can resist different kinds of surfactants in a degree. The amphiphilic BBCPs with controlled molecular weights and narrow molecular weight distributions were synthesized by ring-opening metathesis polymerization of norbornyl-poly (ethylene glycol) (NPEG) and norbornyl-trithiocarbonates (NTTA) followed by reversible addition-fragmentation chain transfer (RAFT) with styrene. GPC and 1HNMR were used to characterize BBCPs. Turbidity measurements, transmission electron microscopy, and scanning electron microscopy were used to explore the morphologies of the aggregation. Depending on the content of water added, many intermediate structures like compound vesicles and sphere could be found. After lyophilization, the BBCP vesicles happended a fusion and can retain vesicle morphology and show some stability in the presence of sodium dodecyl sulfate (SDS), hexadecyl trimethyl ammonium bromide (CTAB), Brij 78P and sodium chloride. This work serves a promising way to construct stable vesicles with BBCPs for biomedical applications.

Photo/pH-controlled host–guest interaction between an azobenzene-containing block copolymer and water-soluble pillar[6]arene as a strategy to construct the “compound vesicles” for controlled drug delivery

Herein, dual stimuli-responsive compound vesicles were constructed based on host-guest interaction between a water-soluble pillar[6]arene (WP6) and an amphiphilic azobenzene-containing block copolymers (BCP). Reversible morphological transformation between compound vesicles and solid aggregates was achieved by repeated pH- and photo-stimuli. These compound vesicles were then applied in the controlled release of water-soluble anticancer drug, doxorubicin hydrochloride (DOX · HCl). Upon external stimuli, the DOX · HCl displayed a faster release rate than that without stimuli. Moreover, the compound vesicles showed an excellent cytocompatibility toward the human breast cancer cells (Michigan Cancer Foundation-7, MCF-7), and the drug-loaded compound vesicles exhibited lower cytotoxicity than free drug. The drug-loaded compound vesicles could be taken up by MCF-7 cells and can release the DOX · HCl in cancer cells due to the acid environment, which was important for applications in the therapy of cancers as a controlled-release drug carrier.

A new cave-dwelling species of Deuteraphorura from northern Italy (Collembola, Onychiuridae).

A new cave-dwelling species, Deuteraphorura pieroluccii sp. n., is described from northern Italy. The size of adult specimens, number, and distribution of dorsal and ventral pseudocelli, and number of compound vesicles of the post antennal organ were used to distinguish it among other congeneric species.

Stomatocyte in Stomatocyte: A New Shape of Polymersome Induced via Chemical-Addition Methodology.

Accurate control of the shape transformation of polymersome is an important and interesting challenge that spans across disciplines such as nanomedicine and nanomachine. Here, we report a fast and facile methodology of shape manipulation of polymersome via out-of-equilibrium polymer self-assembly and shape change by chemical addition of additives. Due to its increased permeability, hydrophilicity, and fusogenic properties, poly(ethylene oxide) was selected as the additive for bringing the system out of equilibrium via fast addition into the polymersome organic solution. A new shape, stomatocyte-in-stomatocyte (sto-in-sto), is obtained for the first time. Moreover, fast shape transformation within less than 1 min to other relevant shapes such as stomatocyte and large compound vesicles was also obtained and accurately controlled in a uniform dispersion. This methodology is demonstrated as a general strategy with which to push the assembly further out of equilibrium to generate unusual nanostructures in a controllable and fast manner.