Nonionic Block Copolymer Research Articles

Comparative Analysis of Bare and Quercetin-Loaded Nonionic Block Copolymer Micelles in an Artificial Gastrointestinal Medium.

Block copolymer micelles have been increasingly used for the solubilization and delivery of hydrophobic drugs. There exists a possibility of dissociation of micelles and formation of other association structures in contact with the gastrointestinal fluid. In this study, we demonstrated the effect of the fed-state intestinal fluid (FeSSIF) upon characteristics of bare and quercetin (QCT)-loaded pluronic 123 (P123) micelles. Characterizations were performed using dynamic light scattering (DLS), 1H NMR, heteronuclear single-quantum coherence (HSQC), two-dimensional 1H-1H nuclear Overhauser effect spectroscopy (2D-NOESY), and diffusion-ordered spectroscopy (DOSY). In the case of bare micelles, we found copolymer-bile salt mixed aggregates without any noticeable change in size. DOSY data revealed that lecithin formed a separate aggregate in the FeSSIF. Complete micellar solubilization of QCT could be verified by the disappearance of its proton signals. At higher dose levels, the diffusion coefficient of micelles increased in the FeSSIF. We speculate that QCT-induced hydrophobicity and availability of FeSSIF components would have driven the formation of small-sized mixed assemblies. On the contrary, the diffusion coefficient of micelles decreased with an increase in the QCT load in the medium devoid of FeSSIF components. We deduce that lack of lecithin and bile salts precluded the formation of mixed assemblies in this case, and therefore, micelles turned heavier at higher QCT loads. Such insights on self-assembled formulations can be valuable in improving their biological performance.

Polypiperazine-Based Micelles of Mixed Composition for Gene Delivery.

We introduce a novel concept in nucleic acid delivery based on the use of mixed polymeric micelles (MPMs) as platforms for the preparation of micelleplexes with DNA. MPMs were prepared by the co-assembly of a cationic copolymer, poly(1-(4-methylpiperazin-1-yl)-propenone)-b-poly(d,l-lactide), and nonionic poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) block copolymers. We hypothesize that by introducing nonionic entities incorporated into the mixed co-assembled structures, the mode and strength of DNA binding and DNA accessibility and release could be modulated. The systems were characterized in terms of size, surface potential, buffering capacity, and binding ability to investigate the influence of composition, in particular, the poly(ethylene oxide) chain length on the properties and structure of the MPMs. Endo-lysosomal conditions were simulated to follow the changes in fundamental parameters and behavior of the micelleplexes. The results were interpreted as reflecting the specific structure and composition of the corona and localization of DNA in the corona, predetermined by the poly(ethylene oxide) chain length. A favorable effect of the introduction of the nonionic block copolymer component in the MPMs and micelleplexes thereof was the enhancement of biocompatibility. The slight reduction of the transfection efficiency of the MPM-based micelleplexes compared to that of the single-component polymer micelles was attributed to the premature release of DNA from the MPM-based micelleplexes in the endo-lysosomal compartments.

High-efficiency triplet-triplet annihilation upconversion microemulsion with facile preparation and decent air tolerance.

Current research of triplet-triplet annihilation upconversion (TTA-UC) faces difficulty such as overuse of organic solvents and quenching of excited triplet sensitizers by molecular oxygen. Herein, we propose an efficient and facile preparation strategy of TTA-UC microemulsion to overcome these issues. With simple device and short preparation process, air-stable TTA-UC with a high upconversion efficiency of 16.52% was achieved in microemulsion coassembled from TritonX114, tetrahydrofuran and upconverting chromophores (platinum octaethyl-porphyrin and 9,10-diphenylanthracene). This is comparable to the highest UC efficiency ever reported for TTA-UC microemulsion systems. The excellent UC performance of TX114-THF could be attributed to two perspectives. Firstly, small-size micelle accommodated chromophores up to high concentrations in organic phase, which promoted efficient molecular collision. Additionally, high absorbance at 532nm ensured full use of excitation light, getting more long wavelength photons involved in the TTA-UC process. Moreover, air-stable TTA-UC also performed well in microemulsion with various surfactants, including nonionic surfactants (Tween 20, Tween 80, Triton X-110, Triton X-114), ionic surfactants (sodium dodecyl sulfate, cetyltrimethyl ammonium bromide) and block copolymers (pluronic F127, pluronic P123), through three conjectural assembly models according to the structural characteristics of surfactant molecules (concentrated, uncompacted and scattered). These discoveries could provide estimable reference for selection of surfactants in relevant fields of TTA-UC.

STUDY OF EXTRACTION OF SORBIC AND BENZOIC ACIDS USING BLOCK COPOLYMER “PLURONIC”

characterized by the use of harmless, environmentally friendly reagents. The relevance of the work is due to the increasing requirements for extractants capable of ensuring almost complete extraction of sorbic and benzoic acids from food objects for the purpose of their subsequent quantitative determination. The work is devoted to studying the extracting ability of the Pluronic block copolymer in relation to sorbic and benzoic acids and establishing the patterns of interphase distribution in the studied systems. Nonionic surfactant block copolymers of ethylene oxide and propylene oxide provide high quantitative indicators of interfacial distribution of a wide class of organic substances. In small quantities, sorbic and benzoic acid in food products do not have a negative effect on human health, but high levels of preservatives cause pathologies in the body. Therefore, the development of new methods for the extraction and determination of sorbic and benzoic acids in aqueous media with the aim of further monitoring their content in food objects is an urgent task of analytical chemistry. The article presents the calculated distribution coefficients and the degree of extraction of sorbic and benzoic acids using the Pluronic block copolymer and ammonium sulfate as an extractant. The concentrations of analytes and extractant, as well as the ratio of the volumes of aqueous and organic phases at which maximum extraction characteristics are achieved, have been established. Еlectrophoretic analysis of the aqueous phase after extraction is used in the work. Parameters for the quantitative determination of sorbic and benzoic acids were established. Schemes for the interaction of the block copolymer with analytes due to hydrogen bonds are proposed, taking into account the structural features of Pluronic and the extracted substances. For citation: Pakhomova O.A., Polteva A.V., Mokshina N.Ya. Study of extraction of sorbic and benzoic acids using block copolymer “Pluronic”. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 7. P. 41-47. DOI: 10.6060/ivkkt.20246707.7020.

Oil mediated polymer based green synthesis of calcium hydroxide nanoparticles and their application in bone conservation

Abstract The present research is characterized by ecofriendly, low cost and robust methods to synthesize calcium hydroxide (CH) nanoparticles using clove oil as capping and reducing agent and nonionic block copolymers as surface modifiers and particle size reducers. The prepared nanoparticles were characterized using UV–visible spectroscopy, dynamic laser light scattering, X-ray diffraction, Fourier transform infra-red spectroscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. The average effective diameter and crystallite size of particle calculated from DLS and XRD were 97–178 and 22–36 nm respectively. The synthesized NPs showed excellent catalytic activities against Allura red and Fast green dye. They also showed improved anti-bacterial and antifungal activities against Staphylococcus aureus, Klebsiella pneumonia and Candida albicans with minimum inhibitory concentration of 50 μl ml−1. The prepared nanocrystals were also incorporated into gum Arabic to be used as consolidant for archaeological bone fragments to fill the cracks, reinforce their mechanical features and save them from further decay. The SEM images of all the bone fragments before and after treatment clearly specify the effectiveness of this treatment.

Molecular Insights on Morphology, Composition, and Stability of Mixed Micelles Formed by Ionic Surfactant and Nonionic Block Copolymer in Water Using Coarse-Grained Molecular Dynamics Simulations.

The nanoscale association domains are the ultimate determinants of the macroscopic properties of complex fluids involving amphiphilic polymers and surfactants, and hence, it is foremost important to understand the role of polymer/surfactant concentration on these domains. We have used coarse-grained molecular dynamics simulations to investigate the effect of polymer/surfactant concentration on the morphology of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO, i.e., pluronics or poloxamers) block copolymer, and ionic surfactants sodium dodecyl sulfate (SDS), mixed micelles in aqueous solution. The proclivity of the surfactant to form the mixed micelles is also probed using umbrella sampling simulations. In this study, we observed that the core of the pluronic + SDS formed mixed micelles consists of PPO, the alkyl tail of SDS, and some water molecules, whereas the PEO, water, and sulfate headgroups of SDS form a shell, consistent with experimental observations. The micelles are spherical at high-pluronic/low-SDS compositions, ellipsoidal at high-SDS/low-pluronic compositions, and wormlike-cylindrical at high-pluronic/high-SDS compositions. The transitions in micelle morphology are governed by the solvent accessible surface area of mixed aggregates, electrostatic repulsion between SDS-headgroups, and dehydration of PEO and PPO segments. The free energy barrier for SDS escape is much higher in mixed micelles than in pure SDS micelles, indicating a stronger tendency for SDS to form pluronic-SDS mixed micelles.

Synergistic effect of cerium and structure directing agent on drug release behavior and kinetics

This work was mainly aimed at the study of the dual effect of cerium and structure directing agent template concentration, on vancomycin release profiles and kinetics from Ce-substituted mesoporous bioactive glasses (MBGs). MBG based on (20-x) B2O3 - 55 SiO2 – 20 CaO – 5 P2O5 – x Ce2O (x = 0, 1 and 3 mol %) was synthesized by the evaporation-induced self-assembly process using two molar ratios (0.01 and 0.02 molar ratio) of nonionic block copolymer Pluronic® 123 (P123) surfactant. The TGA-DTA, FTIR, and textural features analyses were carried out for the glasses. Moreover, the in vitro bone-forming activity and degradation analysis were tested using simulated body fluid (SBF). The drug loading capacity, drug release profile, and kinetics (using different kinetic models such as first order, Higuchi, Hixson-Crowell, and Baker-Lonsdale models) were determined using vancomycin as a drug model. The results showed that the isotherms of all MBGs fit with type IV isotherms, and the surface area of MBGs synthesized by 0.02 M template was higher than that prepared by 0.01 M, where it ranged from 174.05 m2.g−1 to 256.73 m2.g−1. The pore size diameter was decreased as cerium content increased in all MBGs (decreased from 5.44 to 3.54 nm). Moreover, the MBGs induced the formation of a bone-like apatite layer, and their biodegradation properties can be tailored by controlling glass composition. Furthermore, Ce-free MBGs showed the lowest drug adsorption and the highest drug release percentage. The drug release kinetic was best fitted with Higuchi and Baker-Lonsdale models which denoted that the mechanism of drug release from MBGs was a diffusion release from spherical particles. In conclusion, vancomycin release was controlled by the glass composition. Meanwhile, the MBGs synthesized in this study are proposed to be applied for bone regeneration, bone cancer treatment, and reducing the bacterial activity around the tumor site.Graphical abstract

Meso- and Macroporous Polymer Gels for Efficient Adsorption of Block Copolymer Surfactants.

An understanding of surfactant adsorption at solid-liquid interfaces is important for solving many technological problems. This work evaluates surfactant adsorption abilities of high surface area (200-600 m2/g), high porosity (>90%), hierarchically structured open pore polymer gels. Specifically, the interactions of a nonionic block copolymer surfactant, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO), with three polymer gels, namely, syndiotactic polystyrene (sPS), polyimide (PI), and polyurea (PUA) offering different surface energy values, are evaluated at surfactant concentrations below and well above the critical micelle concentration (CMC). Two distinct surfactant adsorption behaviors are identified from the surface tension and nuclear magnetic resonance data. At concentrations below CMC, the surfactant molecules adsorb as a monolayer on polymer strands, inferred from the Langmuir-type adsorption isotherm, with the adsorbed amount increasing with the specific surface area of the polymer gel. The study reports for the first time that the gels show a strong surfactant adsorption above CMC, with the effective surfactant concentration in the gel reaching several folds of the CMC values. The effective surfactant concentration in the gel is analyzed using surfactant micelle size, polymer surface energy, and pore size of the gel. The findings of this study may have strong implications in liquid-liquid separation problems and in the removal of small dye molecules, heavy metal ions, and living organisms from aqueous streams.

Biocompatible calcium phosphate-based ceramics and composites

Synthetic calcium phosphate (CaP) ceramics and composites are used for medical application because of their outstanding biological performance. Although they are the subject of intensive research, so far no material has been obtained with the unique properties of human bones and teeth. This work review recent author strategies using simulated body fluid media synthesis to obtain novel biomimetic CaPs, as well as the combination of supramolecular self-assembly using non-ionic block copolymers and sol-gel chemistry of alcoxysilanes, to obtain silica-CaP composites with remarkable textural properties applicable to dentistry and orthopedics.

Thermoresponsive Self-Assembly of Twofold Fluorescently Labeled Block Copolymers in Aqueous Solution and Microemulsions.

A nonionic double hydrophilic block copolymer with a long permanently hydrophilic and a small thermoresponsive block is synthesized by reversible addition-fragmentation chain-transfer polymerization (RAFT). By employing a specifically designed chain-transfer agent, the polymer is functionalized with complementary end groups which are suited for Förster resonance energy transfer (FRET). The end group attached to the permanently hydrophilic block of poly(N,N-dimethylacrylamide) pDMAm is designed as a permanently hydrophobic segment ("sticker") comprising a long alkyl chain and the 4-aminonaphthalimide fluorophore. The other end attached to the thermoresponsive block of poly(N-isopropylacrylamide) pNiPAm incorporates a coumarin fluorophore. The temperature-dependent self-assembly of the twofold fluorescently labeled copolymer is studied in pure aqueous solution as well as in an o/w microemulsion by several techniques including turbidimetry, dynamic light scattering (DLS), and fluorescence spectroscopy. It is compared to the behaviors of the analogous twofold-labeled pDMAm and pNiPAm homopolymer references. The findings indicate that the block copolymer behaves as a polymeric surfactant at low temperatures, with one relatively small hydrophobic end block and an extended hydrophilic chain forming "hairy micelles". At elevated temperatures above the LCST phase transition of the pNiPAm block, however, the copolymer behaves as an associative telechelic polymer with two nonsymmetrical hydrophobic end blocks, which do not mix. Thus, instead of a network of bridged "flower micelles", large dynamic aggregates are formed. These are connected alternatingly by the original micellar cores as well as by clusters of the collapsed pNiPAm blocks. This type of structure is even more favored in the o/w microemulsion than in pure aqueous solution, as the microemulsion droplets constitute an attractive anchoring point for the hydrophobic dodecyl sticker but not for the collapsed pNiPAm chains.

Structure and composition of mixed micelles formed by nonionic block copolymers and ionic surfactants in water determined by small-angle neutron scattering with contrast variation

HypothesisComplex fluids comprising polymers and surfactants exhibit interesting properties which depend on the overall composition and solvent quality. The ultimate determinants of the macroscopic properties are the nano-scale association domains. Hence it is important to ascertain the structure and composition of the domains, and how they respond to the overall composition. ExperimentsThe structure and composition of mixed micelles formed in aqueous solution between poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers (Pluronics or Poloxamers) and the ionic surfactant sodium dodecylsulfate (SDS) are determined from an analysis of small-angle neutron scattering (SANS) intensity data obtained at different contrasts. Different polymers and concentrations have been probed. FindingsThe SDS + Pluronic mixed micelles include polymer and some water in the micelle core that is formed primarily by alkyl chains. This is different than what was previously reported, but is consistent with a variety of experimental observations. This is the first report on the structure of SDS + Pluronic P123 (EO19PO69EO19) assemblies. The effects on the mixed micelle structure and composition of the surfactant concentration and the polymer hydrophobicity are discussed here in the context of interactions between the different components.

Influence of Surfactant-Mediated Interparticle Contacts on the Mechanical Stability of Supraparticles.

Colloidal supraparticles are micron-scale spherical assemblies of uniform primary particles, which exhibit emergent properties of a colloidal crystal, yet exist as a dispersible powder. A prerequisite to utilize these emergent functionalities is that the supraparticles maintain their mechanical integrity upon the mechanical impacts that are likely to occur during processing. Understanding how the internal structure relates to the resultant mechanical properties of a supraparticle is therefore of general interest. Here, we take the example of supraparticles templated from water/fluorinated oil emulsions in droplet-based microfluidics and explore the effect of surfactants on their mechanical properties. Stable emulsions can be generated by nonionic block copolymers consisting of a hydrophilic and fluorophilic block and anionic fluorosurfactants widely available under the brand name Krytox. The supraparticles formed in the presence of both types of surfactants appear structurally similar, but differ greatly in their mechanical properties. While the nonionic surfactant induces superior mechanical stability and ductile fracture behavior, the anionic Krytox surfactant leads to weak supraparticles with brittle fracture. We complement this macroscopic picture with Brillouin light spectroscopy that is very sensitive to the interparticle contacts for subnanometer-thick adsorbed layers atop of the nanoparticle. While the anionic Krytox does not significantly affect the interparticle bonds, the amphiphilic nonionic surfactant drastically strengthens these bonds to the point that individual particle vibrations are not resolved in the experimental spectrum. Our results demonstrate that seemingly subtle changes in the physicochemical properties of supraparticles can drastically impact the resultant mechanical properties.

Mesoscale Control of PGM Electrocatalysts Using Self-Assembled Block Copolymer Templates

Platinum Group Metals (PGMs) are state-of-the-art electrocatalysts for electrochemical energy conversion technologies. This talk presents a templating approach for the fabrication of dense and periodic platinum and iridium oxide nanowires and standing cylinders with tuned feature sizes (e.g., 12 to 40 nm) and long-range order from self-assembled block copolymer thin films. Unlike previous studies, we show that a starting template utilizing an ion-containing block copolymer electrolyte over a non-ionic block copolymer yields thicker and denser metal/metal oxide nanostructures. PGM geometry and chemical composition were characterized using electron microscopy, atomic force microscopy, grazing incidence x-ray scattering, x-ray photoelectron spectroscopy, and inductively coupled plasma – optical emission spectrometry. The structural characterization tools show high-fidelity pattern transfer from the block copolymer template to the PGM nanostructure. Additionally, the templating process was conducive for preparing the nanostructured PGMs on glassy carbon disks and interdigitated electrodes (IDEs) for electrochemical reactivity assessments. The former substrates were used to assess HER and ORR in a conventional rotating disk electrode setup, while the latter platform was amenable for hydrogen pump and water electrolysis demonstrations with thin film low-temperature and high-temperature polymer electrolytes. Electrochemical measurements revealed a commensurate trend between PGM surface area and mass activity. In summary, the block copolymer templating approach represents a unique platform for high throughput comparative analyses of the intrinsic catalytic activity as a function of meso-scale geometry. It is also an effective platform to understand electrocatalytic reactivity differences for a given catalyst with different types of electrolytes.

Size Effect of Hydroxide Nanobuilding Blocks and Nonionic Block Copolymer Templates on the Formation of Ordered Mesoporous Structures.

The use of precrystallized nanoparticles as nanobuilding blocks (NBBs) is a promising way to obtain mesoporous materials with crystalline walls. In this study, the size effects of both hydroxide NBBs and nonionic block copolymer (BCP) templates on the formation of ordered mesostructures are investigated. The diameter of layered nickel hydroxide NBBs was controlled at the sub-2 nm scale by an epoxide-mediated alkalinization process. Commercially available nonionic BCPs (gyration radii in the range of 11.9-43.9 Å) were used. Mesoperiodic structures were formed by the evaporation-induced self-assembly process. A proper size combination of hydroxide NBBs, smaller than 12.5 Å, and BCPs, larger than 19.9 Å, is shown to be necessary to form ordered mesostructures.

Labelled micelles for the delivery of cytotoxic Cu(II) and Ru(III) compounds in the treatment of aggressive orphan cancers: Design and biological in vitro data

A recent study on our metal-dithiocarbamato complexes pointed out the antiproliferative properties and the druglikeness of some new patented derivatives. In this work, the best compounds have been encapsulated in micellar nanocarriers, being also carbohydrate-functionalized on their hydrophilic surface to investigate the possibility of a cancer-selective delivery. In particular, the nonionic block copolymer Pluronic® F127 (PF127) has been chemically modified with sugars and the derivatives characterized by means of NMR spectroscopy and FT-IR spectrophotometry. Then, the two selected complexes (β-[Ru2(PipeDTC)5]Cl (PipeDTC = piperidine dithiocarbamate) and [Cu(ProOMeDTC)2] (ProOMeDTC = L-proline methyl ester dithiocarbamate)), have been loaded into the hydrophobic core of PF127 micelles and cancer-targeting counterparts. These nanoformulations have been studied for their dimensions (DLS, TEM) and stability, and tested for their cytotoxicity against aggressive human cancer cell lines. The in vitro results were paralleled with mechanistic studies through Confocal Laser Scanning Microscopy and xCELLigence analysis.

Depletion Forces Induced by Mixed Micelles of Nonionic Block Copolymers and Anionic Surfactants.

Depletion forces were measured between a silica sphere and a silica plate in solutions containing nonionic Pluronic P123 poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) triblock copolymers and anionic sodium dodecyl sulfate (SDS) surfactants using colloidal probe atomic force microscopy. Prior research established synergistic depletion force enhancement in solutions containing SDS and unimeric Pluronic F108 block copolymers via formation of large pseudo-polyelectrolyte complexes. The current work addresses a more complex system where the polymer is above its critical micelle concentration, and surfactant binding alters not only the size and charge of the micelles but also the number of polymers per micelle. Force profiles were measured in 10 000 ppm P123 (1 wt %, corresponding to 1.72 mM based on average molar mass) solutions containing SDS at concentrations up to 64 mM and compared to micellar P123 solutions and to P123-free SDS solutions. Whereas force profiles in the SDS-free micellar P123 solutions were purely repulsive, P123/SDS complexation produced synergistic depletion force enhancement for SDS concentrations between 2 and 32 mM. The synergism that occurred within a finite SDS concentration range was explained by comparing the hydrodynamic size, molar mass, charge, and concentration of depletants in P123/SDS mixtures and their respective single-component solutions obtained with the aid of dynamic light scattering, static light scattering, and dodecyl sulfate ion-selective electrode measurements. These measurements showed that complexation produced effects that would be mutually counteracting with respect to depletion forces: decreasing the mixed micelle hydrodynamic diameter relative to SDS-free P123 micelles would tend to weaken depletion forces, while adding charge and decreasing the aggregation number of polymers per micelle (thereby increasing the number concentration of micellar depletants) would tend to strengthen depletion forces.

Quillaic Acid–Containing Saponin-Based Immunoadjuvants Trigger Early Immune Responses

Immunoadjuvants have major effects on the immune responses in vaccine formulations. Many specific adjuvants have been studied, including mineral salts, emulsions, cytokines, non-ionic block copolymers, carbohydrate polymers, muramyl dipeptides, and saponin-based adjuvants. Here, we focus on quillaic acid–containing saponin-based adjuvants and their mechanisms of action. Interestingly, when analyzing the adjuvants capable of forming immune-stimulating complexes, one of the characteristics shared by the majority of them is the presence of quillaic acid as the aglycone. This suggests that quillaic acid might be a strategic molecule for immunoadjuvant activity and a powerful candidate in the development of novel adjuvants.

Study on Synthesized Thermoresponsive Block Copolymer for Water-Based Oil Sands Extraction

Thermoresponsive nonionic block copolymers, methoxy poly(ethylene glycol)-b-poly(N-isopropylacrylamide) (MPEG-b-PNIPAM), were investigated as chemical aids for the water-based oil sands extraction ...

Dynamic tuning of the director field in liquid crystal shells using block copolymers

When an orientationally ordered system, like a nematic liquid crystal (LC), is confined on a self-closing spherical shell, topological constraints arise with intriguing consequences that depend critically on how the LC is aligned in the shell. We demonstrate reversible dynamic tuning of the alignment, and thereby the topology, of nematic LC shells stabilized by the nonionic amphiphilic block copolymer Pluronic F127. Deep in the nematic phase, the director (the average molecule orientation) is tangential to the interface, but upon approaching the temperature TNI of the nematic– isotropic transition, the director realigns to normal. We link this to a delicate interplay between an interfacial tension that is nearly independent of director orientation, and the configurationdependent elastic deformation energy of an LC confined in a shell. The process is primarily triggered by the heating-induced reduction of the nematic order parameter, hence realignment temperatures differ by several tens of degrees between LCs with high and low TNI , respectively. The temperature of realignment is always lower on the positive-curved shell outside than at the negative-curved inside, yielding a complex topological reconfiguration on heating. Complementing experimental investigations with mathematical modeling and computer simulations, we identify and investigate three different trajectories, distinguished by their configurations of topological defects in the initial tangential-aligned shell. Our results uncover a new aspect of the complex response of LCs to curved confinement, demonstrating that the order of the LC itself can influence the alignment and thereby the topology of the system. They also reveal the potential of amphiphilic block copolymer stabilizers for enabling continuous tunability of LC shell configuration, opening doors for in-depth studies of topological dynamics as well as novel applications in, e.g., sensing and programmed soft actuators.

New vaccine technologies, adjuvants and delivery system

Immunization represents the most cost-effective means to achieve the prevention of infectious diseases. Vaccines successfully protected humans from serious infections resulting in worldwide eradication of smallpox and regional elimination of poliomyelitis. New technologies continue to provide many effective biological products for disease control. Various techniques including recombinant DNA approaches, peptide synthesis chemistry, and immunomodulation have been applied to the development of new vaccines and improvement of existing vaccines. These technologies have constructed avirulent and attenuated strains to be used as live vaccines, as well as provided more effective manufacturing methods to produce protein antigens. bacterial polysaccharides (PS) and PS-protein conjugate vaccines. Adjuvant is an agent added to biologics that augments specific immune responses to antigens. Adjuvants can be divided into several classes including aluminum salts, surface-active agents, bacterial derivatives and slow-release materials. Nonionic block copolymer as a multiple emulsion, and proteinoid microspheres were also developed for use in various vaccines. The ideal vaccine delivery system depends on the capabilities of the controlled delivery system to achieve optimum concentration of antigens, while maintaining vaccine stability under physiological conditions. Microspheres were used for controlled release of antigens whereas peptides of monoclonal antibodies were applied for enhancement of mucosal IgA antibody formation.