Polymer Capsule Research Articles

A novel organic-inorganic hybrid hollow polymer capsule with rich amino/imino groups for anionic contaminant removal in wastewater: Synthesis, performance and mechanism

Herein, we developed a new organic-inorganic hybrid polymer adsorbent, termed PECP, by one-step precipitation polycondensation between polyethyene polyamine and hexachlorocyclotriphosphazene. The morphology and microstructure of PECP were investigated by FTIR, SEM, TEM, XPS, XRD and N2 adsorption. Results show PECP owned a hollow capsule structure and lots of amino/imino groups. The adsorption capacity of PECP for anionic dye methyl orange (MO) was up to 1031.9 mg g-1. The adsorption process was very fast. After five cycles, the adsorption capacity of PECP for MO still remained at 89 % of the initial adsorption capacity. Meanwhile, PECP delivered a high adsorption capacity for other anionic contaminants like acid chrome blue K (1003.5 mg g-1), congo red (1152.2 mg g-1) and diclofenac sodium (914.2 mg g-1). In the binary systems contaminated with double dyes, the separation factors of MO for methylene blue, Rhodamine B and crystal violet were up to 450.8, 55.4 and 355.9, respectively. The experimental data unveiled that the MO removal by PECP was very consistent with the pseudo-second-order kinetic model and the Langmuir isotherm model. The removal process was spontaneous and endothermic. FTIR spectroscopy and XPS analysis confirmed the role of electrostatic force and hydrogen bond on the adsorption of MO on PECP.

Preparation and Identification of Magnetic Iron Nanoparticle based on a Natural Hydrogel and its Performance in Targeted Drug Delivery

Billions of dollars are spent annually in the world to treat and investigate problems caused by drug side effects. According to the estimates of health researchers, about 40%of people who take medicine suffer from side effects. In this way, the necessity of using a targeted system in order to deliver medicine to the desired place without damaging healthy tissues is felt more than ever. In recent years, targeted drug delivery systems based on nanoparticles have received much attention. Meanwhile, the use of natural polymers is more suitable for various purposes in drug delivery systems in terms of indicating greater biological compatibility with the body and being non-toxic.In this research, the natural hydrogel extracted from the seeds of the Plantago ovata, which is loaded on the bed of magnetic iron nanoparticles, was used to entrap the drugmefenamic acid. In order to achieve this goal, at the beginning, magnetic iron nanoparticles were prepared by co-precipitation method using iron (II) and iron (III) oxides, and then a coating of silica was created on its surface, then the hydrocolloid of Plantago ovata was extracted from its seed, in order to connect the magnetite nanoparticles and the polymer extracted from the Plantago ovata, the surface of both components was modified by vinyl-functional groups. Next, radical polymerization under heat was used to connect the particles and trap the drug, after that the release of the drug from the polymer capsule was checked by UV-Vis device. Before examining the drug release, the resulting product was identified by FT-IR, XRD, VSM, DLS, TGA, SEM analysis. Therefore, the obtained results indicated that the natural polymer was correctly loaded on the desired magnetic substrate and the drug mefenamic acid was trapped inside the hydrogel networks and polymer capsule. Therefore, the drug can be directed in a controlled and targeted manner by the magnetic field, and the release of the drug was done well and at an acceptable speed.

Inorganic Nanoparticles Embedded in Polydimethylsiloxane Nanodroplets.

To stabilize and transport them through complex systems, nanoparticles are often encapsulated in polymeric nanocarriers, which are tailored to specific environments. For example, a hydrophilic polymer capsule maintains the circulation and stability of nanoparticles in aqueous environments. A more highly designed nanocarrier might have a hydrophobic core and a hydrophilic shell to allow the transport of hydrophobic nanoparticles and pharmaceuticals through physiological media. Polydimethylsiloxane, PDMS, is a hydrophobic material in a liquid-like state at room temperature. The preparation of stable, aqueous dispersions of PDMS droplets in water is problematic due to the intense mismatch in surface energies between PDMS and water. The present work describes the encapsulation of hydrophobic metal and metal oxide nanoparticles within PDMS nanodroplets using flash nanoprecipitation. The PDMS is terminated by amino groups, and the nanodroplet is capped with a layer of poly(styrenesulfonate), forming a glassy outer shell. The hydrophobic nanoparticles nucleate PDMS droplet formation, decreasing the droplet size. The resulting nanocomposite nanodroplets are stable in aqueous salt solutions without the use of surfactants. The hierarchical structuring, elucidated with small-angle X-ray scattering, offers a new platform for the isolation and transport of hydrophobic molecules and nanoparticles through aqueous systems.

Nanite debuts AI platform for polymer design

Nanite has netted $6 million in seed funding to launch its artificial intelligence platform for designing polymer nanoparticles for nonviral gene delivery. A drug’s delivery mechanism can be as important as the drug itself. For gene therapies, adeno-associated viruses (AAVs) are the most established delivery vehicle. But AAVs have a limited payload and can trigger an immune response. Lipid nanoparticles, which are used in COVID-19 messenger RNA vaccines , are an alternative delivery vehicle. But they tend to get stuck in the liver so aren’t suited for tissue-specific delivery. Polymer nanoparticles are the latest nonviral delivery alternatives. Their main advantage is their chemical diversity, says Sean Kevlahan, Nanite’s CEO and cofounder. Their resulting versatility allows scientists to tailor polymers for different cargo and tissue targets. The polymer capsule involves many design considerations, including the monomer chemistry, polymer architecture, and surface charge distribution. Nanite employs AI to predict the design for

Simultaneous Encapsulation of Mixed‐Halide Perovskite on Synthesis Step Using a Thermally Expandable Lamellar Capsule to Fabricate the Multi‐Conversion Layer

AbstractDespite the excellent performance of halide perovskite, low stability, and ion exchange between halides have remained obstacles to practical application. Herein, the polymer capsule encapsulated perovskite through the conventional hot‐injection method is reported to overcome the above issues. The residual heat generated during perovskite synthesis is utilized to expand the layer, and the perovskite particles are grown inside the polyethylene capsule. The products are gathered in a powder state, and the whole emission range can be synthesized. The water stability after 6 h soaked in water shows ≈90% and ≈75% for green and red, respectively. Also, due to the suppressed ion exchange, the single multi‐conversion layer for white light generation can be fabricated.

Targeted Therapy for Glomerulonephritis Using Arterial Delivery of Encapsulated Etanercept.

Complex immunosuppressive therapy is prescribed in medical practice to patients with glomerulonephritis to help them overcome symptoms and prevent chronic renal failure. Such an approach requires long-term systemic administration of strong medications, which causes severe side effects. This work shows the efficiency of polymer capsule accumulation (2.8 ± 0.4 µm) containing labeled etanercept (100 μg per dose) in the kidneys of mice. The comparison of injection into the renal artery and tail vein shows the significant superiority of the intra-arterial administration strategy. The etanercept retention rate of 18% and 8% ID in kidneys was found 1 min and 1 h after injection, respectively. The capsules were predominantly localized in the glomeruli after injection in mice using a model of acute glomerulonephritis. Histological analysis confirmed a significant therapeutic effect only in animals with intra-arterial administration of microcapsules with etanercept. The proposed strategy combines endovascular surgery and the use of polymer microcapsules containing a high molecular weight drug that can be successfully applied to treat a wide range of kidney diseases associated with glomerular pathology.

Time-Based Formulation Strategies for Colon Drug Delivery.

Despite poor absorption properties, delivery to the colon of bioactive compounds administered by the oral route has become a focus of pharmaceutical research over the last few decades. In particular, the high prevalence of Inflammatory Bowel Disease has driven interest because of the need for improved pharmacological treatments, which may provide high local drug concentrations and low systemic exposure. Colonic release has also been explored to deliver orally biologics having gut stability and permeability issues. For colon delivery, various technologies have been proposed, among which time-dependent systems rely on relatively constant small intestine transit time. Drug delivery platforms exploiting this physiological feature provide a lag time programmed to cover the entire small intestine transit and control the onset of release. Functional polymer coatings or capsule plugs are mainly used for this purpose, working through different mechanisms, such as swelling, dissolution/erosion, rupturing and/or increasing permeability, all activated by aqueous fluids. In addition, enteric coating is generally required to protect time-controlled formulations during their stay in the stomach and rule out the influence of variable gastric emptying. In this review, the rationale and main delivery technologies for oral colon delivery based on the time-dependent strategy are presented and discussed.

Long-Term Antibody Release Polycaprolactone Capsule and the Release Kinetics in Natural and Accelerated Degradation.

Although therapy using monoclonal antibodies (mAbs) has been steadily successful over the last 20 years, the means of delivery of mAbs has not been optimized, especially for long-term delivery. Frequent injections or infusions have been the current standard of care. In this study, we have developed a long-term antibody biodegradable implant using a porous polycaprolactone (PCL) capsule. It released bevacizumab (Bev) slowly for 8 months to date. The Bev release kinetics fit a drug release model with experimental data of the diffusion coefficient and partition coefficient through the polymer capsule. Since screening drug release profiles for the long term (>6 months) is time consuming, an accelerated degradation method was used after validating the characteristics of the PCL capsule in natural and accelerated degradation conditions. The correlation of the time period between natural and accelerated degradation was determined. Overall, the study suggests that mAbs can be released from a porous PCL capsule without an effect of the polymer degradation over a long period (∼6 months) and the long-term release kinetics can be determined by the accelerated degradation within 14 days.

Dopamine as a bioinspired adhesion promoter for the metallization of multi-responsive phase change microcapsules

This work reports on an environmentally friendly method to produce encapsulated phase change material with a thin nickel coating, applicable for heat conversion, storage and thermal management of heat-sensitive components and suitable for active heating by electromagnetic radiation. A critical issue for the metallization is the adhesion between the polymer capsule shell and the metal layer. Based on previous studies using the bio-molecule dopamine as adhesion promoter in composites and for plastics metallization, commercial paraffin microcapsules were coated with an ultrathin polydopamine film via a simple wet chemical process. Subsequently, a thin, uniform and compact nickel layer was produced by electroless metallization. The successful deposition of both layers was verified with a broad range of imaging and spectroscopic techniques. For the first time, surface-enhanced IR spectroscopy was used to study the deposition of ultrathin PDA films. The combination of SEM and energy-dispersive X-ray spectroscopy allowed resolving the spatial distribution of the elements Ni, N, and O in the MC shell. Electrically conducting paths in the Ni shell were verified by conductive AFM. Thermal analysis revealed that the coated microcapsules show a phase change enthalpy of approx. 170 J/g, suitable for thermal storage and management. Additionally, the nickel layer enhanced the thermal diffusivity of the microcapsule powders and enables a fast heating of the PCM microcapsules by microwave radiation, demonstrating the applicability of the metallized MCs for controlled heating applications.Graphical abstract

Printed asymmetric microcapsules: Facile loading and multiple stimuli-responsiveness.

Engineering of colloidal particles and capsules despite substantial progress is still facing a number of unsolved issues including low loading capacity, non-uniform size and shape of carriers, tailoring different functionalities and versatility to encapsulated cargo. In this work, we propose a method for defined-shaped functionally asymmetric polymer capsule fabrication based on a soft lithography approach. The developed capsules consist of two classes of polymers - the main part "cup" is made out of polyelectrolyte multilayers (PAH-PSS) and "lid" is made of biodegradable polyether (PLGA). Asymmetric capsules combine advantages from both traditional layer-by-layer capsules and recently developed printed "pelmeni" capsules. This combination provides stimuli-responsiveness due to polyelectrolyte multilayer properties differing from PLGA. The inner volume of capsules can be loaded with a variety of active compounds and the capsule's geometry is defined due to the soft-lithography method. Capsules have a core-shell structure and monodisperse size distribution. Three methods to trigger cargo release have been demonstrated, namely temperature treatment, ultrasonication and pH shift. Steroidal drug dexamethasone was used to illustrate the applicability of the systems for triggered drug release. The application of proposed asymmetric capsules includes but is not limited to pharmacology, diagnostics, sensors, micro- and nanoreactors and chemical actuators.

Drug diffusion and release from a bioerodible spherical capsule

Controlled release of a drug contained in a spherical polymer capsule is of significant interest in many fields of medicine. There is growing interest in tailoring the erosion properties of the drug to help control and optimize the drug release process. Theoretical understanding of the nature of drug release from a bioerodible capsule is, therefore, important for designing effective drug delivery systems. While drug release from a fixed-radius capsule is relatively easier to model, the shrinking nature of a bioerodible capsule due to surface erosion presents several difficulties in theoretical modeling. This work presents a closed-form solution for the drug concentration distribution and drug delivery characteristics from a spherical capsule undergoing linear surface erosion. This problem is solved by a transformation that converts the moving boundary problem into a fixed boundary problem. For uniform initial drug distribution, the solution is shown to depend on a single non-dimensional parameter. The theoretical model is used to develop an understanding of the impact of varying the drug diffusion coefficient and rate of erosion on drug delivery characteristics. It is found that, in general, the nature of drug release in a bioerodible sphere is determined by a delicate balance between two simultaneously occurring processes – erosion and diffusion. This work improves the theoretical understanding of diffusion in drug delivery systems by accounting for the practical erosion phenomena, and may contribute towards the design and optimization of drug delivery systems.

A 3D bioprinted hybrid encapsulation system for delivery of human pluripotent stem cell-derived pancreatic islet-like aggregates

Islet transplantation is a promising treatment for type 1 diabetes. However, treatment failure can result from loss of functional cells associated with cell dispersion, low viability, and severe immune response. To overcome these limitations, various islet encapsulation approaches have been introduced. Among them, macroencapsulation offers the advantages of delivering and retrieving a large volume of islets in one system. In this study, we developed a hybrid encapsulation system composed of a macroporous polymer capsule with stagger-type membrane and assemblable structure, and a nanoporous decellularized extracellular matrix (dECM) hydrogel containing pancreatic islet-like aggregates using 3D bioprinting technique. The outer part (macroporous polymer capsule) was designed to have an interconnected porous architecture, which allows insulin-producing β-cells encapsulated in the hybrid encapsulation system to maintain their cellular behaviors, including viability, cell proliferation, and insulin-producing function. The inner part (nanoporous dECM hydrogel), composed of the 3D biofabricated pancreatic islet-like aggregates, was simultaneously placed into the macroporous polymer capsule in one step. The developed hybrid encapsulation system exhibited biocompatibility in vitro and in vivo in terms of M1 macrophage polarization. Furthermore, by controlling the printing parameters, we generated islet-like aggregates, improving cell viability and functionality. Moreover, the 3D bioprinted pancreatic islet-like aggregates exhibited structural maturation and functional enhancement associated with intercellular interaction occurring at the β-cell edges. In addition, we also investigated the therapeutic potential of a hybrid encapsulation system by integrating human pluripotent stem cell-derived insulin-producing cells, which are promising to overcome the donor shortage problem. In summary, these results demonstrated that the 3D bioprinting approach facilitates the fabrication of a hybrid islet encapsulation system with multiple materials and potentially improves the clinical outcomes by driving structural maturation and functional improvement of cells.

Determination of the Oxygen Concentration in GDP Thin Films Using Rutherford Backscattering Spectroscopy

The oxygen concentration in the glow discharge polymer (GDP) capsule is one of the perturbations that most limit implosion quality. In order to investigate the feasibility of the Rutherford backscattering (RBS) technique for characterizing the oxygen concentration in a GDP capsule, the basic principle of RBS and the experimental conditions are introduced first. Then, the irradiation damage effect of incident ions on the GDP film is simulated numerically. The simulated results demonstrate that the GDP films will be damaged by the incident ions, and the vacancy damage dominates in irradiation modification. Finally, some GDP thin films are measured using RBS, and the oxygen concentration and its depth profile are obtained from the measured RBS spectrum. The simulated and experimental results prove that the oxygen concentration of GDP films can be measured precisely using RBS with an uncertainty of about 3.5%.

Design of New Polyacrylate Microcapsules to Modify the Water-Soluble Active Substances Release.

Despite the poor photochemical stability of capsules walls, polyacrylate is one of the most successful polymers for microencapsulation. To improve polyacrylate performance, the combined use of different acrylate-based polymers could be exploited. Herein butyl methacrylate (BUMA)-based lattices were obtained via free radical polymerization in water by adding (i) methacrylic acid (MA)/methyl methacrylate (MMA) and (ii) methacrylamide (MAC) respectively, as an aqueous phase in Pickering emulsions, thanks to both the excellent polymer shells’ stability and the high encapsulation efficiency. A series of BUMA_MA_MMA terpolymers with complex macromolecular structures and BUMA_MAC linear copolymers were synthesized and used as dispersing media of an active material. Rate and yield of encapsulation, active substance adsorption onto the polymer wall, capsule morphology, shelf-life and controlled release were investigated. The effectiveness of the prepared BUMA-based microcapsules was demonstrated: BUMA-based terpolymers together with the modified ones (BUMA_MAC) led to slow (within ca. 60 h) and fast (in around 10 h) releasing microcapsules, respectively.

The acoustic radiation force on a multi-layered polymer capsule placed in a fluid-filled tube

Acoustic manipulation has a series of application in biomedicine, colloidal assembly, and chemistry. A three-layered polymer capsule is generally used structure in manipulation system because it has better protection to the core filled drug or compounds and possesses higher flexibility. In this paper, a theoretical model of acoustic radiation force acting on a three-layered drug capsule in a vessel is established. The acoustic radiation force on a capsule, which comprises of a drug core, a poly(lactide-co-glycolide) mid shell and a chitosan outer shell in the cylindrical tube filled with ideal fluid, is calculated using acoustic wave theory. The influences of the tube, the surrounding fluid and the geometric size of chitosan, poly(lactide-co-glycolide) shell and drug core on acoustic radiation force are investigated. The numerical simulations based on finite element method are introduced to compute the acoustic radiation force and compared with the analytical results. Moreover, the comparison among the capsule in impedance tube, in rigid tube and in unbounded space is obtained simulating specific environment. Simulation results show that the influences of the rigid tube on the acoustic radiation force of the capsule can be ignored when the capsule is much smaller than the radius of the tube. With the increase of the capsule radius, the acoustic radiation force of the capsule changes demonstrably with the frequency and the tube radius because of the influence of the reflective wave resulted from the inner surface of the tube. The properties of the surrounding fluid affect the position of the resonant peaks. Outer radius and mid layer radius have more effects on the acoustic radiation force, but the drug core radius almost exerts no effect on it. The study illustrates that the capsule can be manipulated by acoustic wave with the suitable selection for the outer or mid shell radii, and the selection of drug core radius is of more freedom in this process.

Effect of salts on size and morphology of extruded dimethyldioctadecylammonium bromide or chloride vesicle for polymeric nanocapsules synthesis via templating emulsion polymerization

In preparing polymer capsules by vesicle templated emulsion polymerization, the initial size and morphology of the biomimetic vesicle template dictate the final size and morphology of the capsules. The presence of salts (NaCl, NaBr and LiCl) influences the size, dispersity (PDI) and morphology of dimethyldioctadecylammonium bromide or chloride (DODAX, X = Br− or Cl−) vesicles, prepared via membrane extrusion. DODAX vesicles in pure water exhibit broad size distributions with PDI of 0.5 and 0.3 for DODAB and DODAC, respectively. Addition of salts in water before (pre-addition) and after (post-addition) extrusion reduces the size and PDI of the vesicles significantly and results in various morphology investigated with cryo-TEM. It is observed that at low salt concentration (≤0.5 mM) in pre-addition, DODAX exists as a nice quasi spherical unilamellar vesicle, suitable for vesicle templated polymerization whereas in post-addition of salt at any concentration, the morphology is dominated by structures not suitable for templating application. The information obtained here is crucial for vesicle templated emulsion polymerization and it will be shown that there is a relationship between vesicle template morphology and final polymer capsule morphology.

'Plate‐like‐coral' polymer particles with dendritic structure and porous channels: Effective delivery of anti‐cancer drugs

Abstract'Plate‐like‐coral' shaped polymer capsule (PC‐PLCDB) with dendritic network structure and porous channels has been synthesized and used for therapeutic purposes. First di‐block copolymer [(PEG)‐b‐(L‐AspA)n] has been synthesized from PEG (polyethylene glycol) and aspartic acid (AspA). Then the biocompatible PC‐PLCDB has been achieved by homogeneous mixing of [(PEG)‐b‐(L‐AspA)n] and poly‐N‐isopropyl acrylamide (PNIPAM) followed by reprecipitation. Only H‐bonding is responsible for the foundation of self‐assembly of the polymer chains and to form PC‐PLCDB. A huge extent of loading anticancer drug, for example, doxorubicin (DOX) in PC‐PLCDB is possible. in vitro study has been performed to check the therapeutic efficacy of PC‐PLCAD‐DOX formulation on chronic myeloid leukemia cells (K562). The IC50 has been calculated to be 0.405 (±0.014) ng μg−1 of the formulation. PC‐PLCAD‐DOX inhibits 80% of the cancer cell only by 1.0 μg mL−1 of the formulation. This study reveals that the PC‐PLCAD could be a promising candidate for therapeutic applications.

Microfluidic interface boosted synthesis of covalent organic polymer capsule

Microcapsules have been widely used in drug carriers, nano/microreactors, artificial organelles for their empty space and functional shell. Microcapsules synthesized from spherical liquid-liquid interface show ultrathin shell and large cavities. However, spherical liquid-liquid interfaces generated by stirring or sonicating are difficult in controlling the droplet size and preventing their coalescence, which results in inhomogeneous capsules. Here, we demonstrate a microfluidic interfacial synthetic method to produce microcapsules using the hot covalent organic polymers (COPs) coupled with Schiff-base reaction. A very high throughput of uniform and individual microdroplets about ~1400 min−1 was generated under high flow rate for COP capsules fabrication. Acidic catalyst promoted amine and aldehyde condensation that reacted less than 1 ​s assured the polymerization occurred at the liquid-liquid interface regardless of the diffusion intensification in microfluidic system. COP capsules with shell thickness around 50 ​nm were flexible enough to response to slight interior capillary force and exterior filtration force to form origami structure and sealed flat membrane, respectively. Each of the interfacial synthesized capsule expressed large capacity by encapsulating 1.41 ​× ​10−2 ​μg SiO2 nanoparticles as theoretically calculated. Thus, these properties make the COP capsules promising in, but not limited to, fast drug delivery and microreactors.

3D crateriform and honeycomb polymer capsule with nano re-entrant and screen mesh structures for the removal of Multi-component cationic dyes from water

In this study, a hybrid sodium alginate-polyvinyl alcohol-silica oxide capsule (SA-PVA-SiO2 capsule, SPSC) was fabricated via the one-step titration-gel method that directly dripped the spherical droplet of the SA, PVA and tetraethyl orthosilicate (TEOS) mixed solutions into the bath with calcium chloride (CaCl2), NaCl and oversaturated boric acid (H3BO3) cross-linking agents. The formation principle of the prepared capsule was investigated. And the adsorptive performance of the SPSC was analyzed by removing the single, binary and multi-component cationic dye solutions [i.e. Methylene Blue (MB), Malachite Green (MG) and Crystal Violet (CV)]. The results indicated that the crateriform and cellular polymer channel with nano screen mesh and re-entrant structures could help to promote the interaction between pollutants and the interface of the SPSC thereby trapping the cationic dyes in its body. In single-component dye solution, the maximal adsorption capacities of the SPSC against MB, MG and CV were respectively found to be 394.077 mg/g, 1034.047 mg/g and 1756.202 mg/g at 25 °C and pH 9. The adsorption mechanism of the cationic dyes by the SPSC was governed by electrostatic attraction and chemisorption. Though the removal capacity of the cationic dyes by the SPSC was reduced in competitive multi-component systems, the saturation adsorption amount of the CV could still maintain above 684,692 mg/g. The affinity between the SPSC and the cationic dyes was in the order of MB > MG > CV. The prepared hydrogel capsule could be used in wide range pH situations. This facile method which was used to produce free-standing spherical support adsorbent with specialized morphology might have good prospects for excessive removing cationic dyes from alkaline wastewater.

Modification of the polyelectrolyte capsule shell by nanodiamonds for remote microwave opening

Nanodiamonds (ND) are one of the most attractive carbon materials for nanotechnology. The impregnation of NDs into the polymer capsule shell in the form of the single nanoparticles insures the control over the thermal conductivity of the capsule shell and increases their sensitivity to the external microwave irradiation. The polymer shell of the polyelectrolyte capsules was modified with NDs by electrostatic adsorption technique. The sensitivity of the capsules with embedded NDs to the external microwave irradiation was demonstrated by scanning electron microscopy leading to the shell rupture and release of the encapsulated agents.