Biodegradable Polyelectrolyte Research Articles

Biodegradable Local Chemotherapy Platform with Prolonged and Controlled Release of Doxorubicin for the Prevention of Local Tumor Recurrence.

Local recurrence after surgical and therapeutic treatment remains a significant clinical problem in oncology. Recurrence may be due to imperfections in existing therapies, particularly chemotherapy. To improve antitumor activity and prevent local cancer recurrence while keeping toxicity at acceptable levels, we have developed and demonstrated a biodegradable local chemotherapy platform that provides controlled and prolonged drug release. The platform consists of a polycaprolactone (PCL) substrate, which provides the structural integrity of the platform and the predominant unidirectional drug release, and a thin multilayer coating (∼200 nm) containing doxorubicin (DOX). The coating is an electrostatic complex obtained by the layer-by-layer (LbL) assembly and consists of natural polyelectrolytes [poly-γ-glutamic acid (γ-PGA) and chitosan (CS) or poly-l-lysine (PLL)]. To improve the release stability, an ionic conjugate of DOX and γ-PGA was prepared and incorporated into the multilayer coating. By varying the structure of the coating by adding empty (without DOX) bilayers, we were able to control the kinetics of drug release. The resulting platforms contained equal numbers of empty bilayers and DOX-loaded bilayers (15 + 15 or 30 + 30 bilayers) with a maximum loading of 566 ng/cm2. The platforms demonstrated prolonged and fairly uniform drug release for more than 5 months while retaining antitumor activity in vitro on ovarian cancer cells (SKOV-3). The empty platforms (without DOX) showed good cytocompatibility and no cytotoxicity to human fibroblasts and SKOV-3 cells. This study presents the development of a local chemotherapy platform consisting of a PCL-based substrate which provides structural stability and a biodegradable polyelectrolyte layered coating which combines layers containing a polyanion ionic complex with DOX with empty bilayers to ensure prolonged and controlled drug release. Our results may provide a basis for improving the efficacy of chemotherapy using drug delivery systems.

Layer by layer self-assembly for coating a nanosuspension to modify drug release and stability for oral delivery

Layer-by-layer (LbL) modification is an effective way to tune the properties of particles. However, the traditional LbL process involves repeated washing steps which are not compatible with nanoparticles with a partial solubility. In this work, we demonstrate the use of a titration method for producing LbL coatings onto a nanosuspension of curcumin (a compound with a limited aqueous solubility). The aim of the work was to show how LbL can be used to enhance the release behaviour and stability of the curcumin in a nanosuspension form. Coated nanosuspension samples were produced using biocompatible and biodegradable polyelectrolytes, poly-l-arginine, and sodium alginate and was sizes approximately 500 nm. A stimuli-responsive nanosuspension was prepared by coating the nanosuspension with 5 layers of poly-l-arginine and alginate and Eudragit L100 as an outmost layer. The in vitro release of these nanosuspensions revealed that the use of a pH-responsive layer (Eudragit L100) as an outermost shell resulted in delay the release of curcumin (5%) in acidic pH and facilities its release in neutral pH (11%) over 72 h. Additionally, the bioaccessibility study showed that increasing the number of layers resulted in increasing the stability curcumin in nanosuspension when exposed to conditions that mimic the gastrointestinal tract from 20% for uncoated nanosuspension to 40% and 90% for 4-layered coated nanosuspension and stimuli-responsive (6-layered) coated nanosuspension, respectively. The cytotoxicity of LbL-coating of nanosuspension revealed a reduction in the toxicity of curcumin. This work shows how a titrated LbL modification approach could be used to tailor the stability and the release behaviour of nanosuspensions for oral drug delivery applications.

D20. Agrin Nanoparticles in a Nanofiber Hydrogel-based Drug Delivery System Improve Neuromuscular Junction Reinnervation following Chronic Denervation

PURPOSE: Following peripheral nerve injury, neuromuscular junctions (NMJs) within denervated muscle rapidly destabilize. Agrin, a proteoglycan essential to NMJ formation, may have an essential role in preserving NMJ receptivity to reinnervation. This study aimed to evaluate the efficacy of agrin-NP therapy in a rodent chronic denervation model. METHODS: Agrin was encapsulated in biodegradable polyelectrolyte:polymer NPs and embedded within a hyaluronic acid/PCL nanofiber hydrogel composite (NHC). The effect of locally delivered agrin-NP/NHC on NMJ reinnervation was assessed using a forelimb chronic denervation nerve injury model. Animals were injected with agrin-NP/NHC, free agrin, or empty-NP/NHC every six weeks from time of nerve injury and underwent 16 weeks of functional assessment. RESULTS: Agrin-NP/NHC animals exhibited significantly increased functional recovery compared to free agrin (p<0.01) and empty-NP/NHC animals (p<0.01) At Week 15, Agrin-NP/NHC animals demonstrated an increase of 21.2% compared to free agrin (p=0.056) and of 26.8% compared to empty-NP/NHC (p<0.05). Agrin-NP/NHC animals demonstrated significantly greater NMJ reinnervation than free agrin (78.9% vs 66.8%, p<0.05) and empty-NP/NHC groups (78.9% vs 39.2%, p<0.001). No significant differences were seen in myofibril cross-sectional area between treatment groups. No foreign body response was detected in empty-NP/NHC or agrin-NP/NHC animals. Agrin levels were undetectable in serum and were significantly higher in agrin-NP/NHC than free agrin animals. CONCLUSION: Agrin-NP/NHC treatment in vivo promotes neuromuscular junction reinnervation and improves functional recovery of forelimb grip strength.

Doxorubicin-Loaded Polyelectrolyte Multilayer Capsules Modified with Antitumor DR5-Specific TRAIL Variant for Targeted Drug Delivery to Tumor Cells

Recently, biodegradable polyelectrolyte multilayer capsules (PMC) have been proposed for anticancer drug delivery. In many cases, microencapsulation allows to concentrate the substance locally and prolong its flow to the cells. To reduce systemic toxicity when delivering highly toxic drugs, such as doxorubicin (DOX), the development of a combined delivery system is of paramount importance. Many efforts have been made to exploit the DR5-dependent apoptosis induction for cancer treatment. However, despite having a high antitumor efficacy of the targeted tumor-specific DR5-B ligand, a DR5-specific TRAIL variant, its fast elimination from a body limits its potential use in a clinic. A combination of an antitumor effect of the DR5-B protein with DOX loaded in the capsules could allow to design a novel targeted drug delivery system. The aim of the study was to fabricate PMC loaded with a subtoxic concentration of DOX and functionalized with the DR5-B ligand and to evaluate a combined antitumor effect of this targeted drug delivery system in vitro. In this study, the effects of PMC surface modification with the DR5-B ligand on cell uptake both in 2D (monolayer culture) and 3D (tumor spheroids) were studied by confocal microscopy, flow cytometry and fluorimetry. Cytotoxicity of the capsules was evaluated using an MTT test. The capsules loaded with DOX and modified with DR5-B demonstrated synergistically enhanced cytotoxicity in both in vitro models. Thus, the use of the DR5-B-modified capsules loaded with DOX at a subtoxic concentration could provide both targeted drug delivery and a synergistic antitumor effect.

Chitosan – dextran phosphate carbamate hydrogels for locally controlled co-delivery of doxorubicin and indomethacin: From computation study to in vivo pharmacokinetics

The development of synergistic drug combinations is a promising strategy for effective cancer suppression. Here, we report all-polysaccharide biodegradable polyelectrolyte complex hydrogels (DPCS) based on dextran phosphate carbamate (DP) and chitosan (CS) for controlled co-delivery of the anticancer drug doxorubicin (DOX) and the non-steroidal anti-inflammatory drug indomethacin (IND). IND can induce more apoptosis in tumor cells by reducing the level of multidrug resistance-associated protein 1. Based on calculations using density functional theory and zeta potential analysis data, carriers with high drug loading were obtained. The release profile of both drugs from the hydrogels was tuned by changing the molecular weight and functional groups content of the polysaccharides. The optimized DPCS showed a steady release of DOX both in vitro and in vivo, and a gradual release of IND, which constantly induced the action of DOX. Considering all of these benefits, DOX- and IND-loaded DPCS offer a promising long-acting polysaccharide-based antitumor platform.

Nano-Assembly of Quisinostat and Biodegradable Macromolecular Carrier Results in Supramolecular Complexes with Slow-Release Capabilities.

Self-assembly of ionically charged small molecule drugs with water-soluble biodegradable polyelectrolytes into nano-scale complexes can potentially offer a novel and attractive approach to improving drug solubility and prolonging its half-life. Nanoassemblies of quisinostat with water-soluble PEGylated anionic polyphosphazene were prepared by gradient-driven escape of solvent resulting in the reduction of solvent quality for a small molecule drug. A study of binding, analysis of composition, stability, and release profiles was conducted using asymmetric flow field flow fractionation (AF4) and dynamic light scattering (DLS) spectroscopy. Potency assays were performed with WM115 human melanoma and A549 human lung cancer cell lines. The resulting nano-complexes contained up to 100 drug molecules per macromolecular chain and displayed excellent water-solubility and improved hemocompatibility when compared to co-solvent-based drug formulations. Quisinostat release time (complex dissociation) at near physiological conditions in vitro varied from 5 to 14 days depending on initial drug loading. Multimeric complexes displayed dose-dependent potency in cell-based assays and the results were analyzed as a function of complex concentration, as well as total content of drug in the system. The proposed self-assembly process may present a simple alternative to more sophisticated delivery modalities, namely chemically conjugated prodrug systems and nanoencapsulation-based formulations.

Mechanistic insights into soil heavy metals desorption by biodegradable polyelectrolyte under electric field

In this study, we firstly used alginate to enhance an electrokinetic technology to remediate soil contaminated with divalent heavy metals (Pb2+, Cu2+, Zn2+). The mechanisms of alginate-associated migration of metal ions in electric field were confirmed. Alginate resulted in a high electrical current during electrokinetic process, and soil conductivity also increased after remediation. Obvious changes in both electroosmotic flow and soil pH were observed. Moreover, these factors were affected by increasing alginate dosage. The highest Cu (95.82%) and Zn (97.33%) removal efficiencies were obtained by introducing 1 wt% alginate. Alginate can desorb Cu2+ and Zn2+ ions from soil by forming unstable gels, which could be dissociated through electrolysis. However, Pb2+ ions did not easily migrate out of the contaminated soil. The density functional theory (DFT) calculations show Pb2+ ions could form a more stable coordination sphere in metal complexes than Cu2+ and Zn2+ ions. The metal removal efficiency was decreased by increasing alginate dosage at a high level. More alginate could provide more carboxyl ligands for divalent metal ions to stabilize gels, which were difficult to dissociate by electrolysis. In summary, the results indicate it is potential for introducing alginate into an electrokinetic system to remediate Cu- and Zn- contaminated soil.

Effect of Poly(L-lysine) and Heparin Coatings on the Surface of Polyester-Based Particles on Prednisolone Release and Biocompatibility.

A plethora of micro- and nanoparticle types are currently investigated for advanced ocular treatment due to improved drug retention times, higher bioavailability and better biocompatibility. Yet, comparative studies of both physicochemical and toxicological performance of these novel drug delivery systems are still rare. Herein, poly(L-lactic acid)- and poly(ε-caprolactone)-based micro- and nanoparticles were loaded with prednisolone as a model drug. The physicochemical properties of the particles were varied with respect to their hydrophilicity and size as well as their charge and the effect on prednisolone release was evaluated. The particle biocompatibility was assessed by a two-tier testing strategy, combining the EpiOcularTM eye irritation test and bovine corneal opacity and permeability assay. The biodegradable polyelectrolyte corona on the particles’ surface determined the surface charge and the release rate, enabling prednisolone release for at least 30 days. Thereby, the prednisolone release process was mainly governed by molecular diffusion. Finally, the developed particle formulations were found to be nontoxic in the tested range of concentrations.

Development of Multifunctional Coating of Textile Materials Using Silver Microencapsulated Compositions

The efficiency of the method for the synthesis of silver nanoparticles using a system containing oxalic dialdehyde as a reducing agent, and polyguanidine as a stabilizer is shown. An analysis of the data of photon correlation spectroscopy characterizing the sizes of the formed particles in the Ag-polyelectrolyte system is presented. It has been established that the synthesized silver nanoparticles have a stable biocidal effect. The system of biodegradable polyelectrolytes chitosan-xanthan gum for the synthesis of the capsule shell including silver nanoparticles is selected. This will allow the formation of stable polyelectrolyte capsule shells containing oyster mushroom mycelium extract. A protocol for the synthesis of microcapsules by the method of sequential adsorption of chitosan polyelectrolytes and xanthan gum on calcium carbonate templates was developed. Silver nanoparticles are included in the capsule shell, and a biologically active drug (oyster mushroom mycelium extract) is included in the core. The technological mode of complex capsules immobilization on a textile material by the layer-by-layer method is described. The immobilization of multilayer microcapsules on a fibrous substrate is provided by a system of polyelectrolytes: positively charged chitosan and negatively charged xanthan gum. The developed multifunctional coatings make it possible to impart multifunctional properties to textile materials: antibacterial, antimycotic, high hygroscopic properties.

Biodegradable polyelectrolyte/magnetite capsules for MR imaging and magnetic targeting of tumors.

Rationale: The tireless research for effective drug delivery approaches is prompted by poor target tissue penetration and limited selectivity against diseased cells. To overcome these issues, various nano- and micro-carriers have been developed so far, but some of them are characterized by slow degradation time, thus hampering repeated drug administrations. The aim of this study was to pursue a selective delivery of magnetic biodegradable polyelectrolyte capsules in a mouse breast cancer model, using an external magnetic field.Methods: Four different kinds of magnetic polyelectrolyte capsules were fabricated via layer-by-layer assembly of biodegradable polymers on calcium carbonate templates. Magnetite nanoparticles were embedded either into the capsules' shell (sample S) or both into the shell and the inner volume of the capsules (samples CnS, where n is the number of nanoparticle loading cycles). Samples were first characterized in terms of their relaxometric and photosedimentometric properties. In vitro magnetic resonance imaging (MRI) experiments, carried out on RAW 264.7 cells, allowed the selection of two lead samples that proceeded for the in vivo testing on a mouse breast cancer model. In the set of in vivo experiments, an external magnet was applied for 1 hour following the intravenous injection of the capsules to improve their delivery to tumor, and MRI scans were acquired at different time points post administration.Results: All samples were considered non-cytotoxic as they provided more than 76% viability of RAW 264.7 cells upon 2 h incubation. Sample S appeared to be the most efficient in terms of T2-MRI contrast, but the less sensitive to external magnet navigation, since no difference in MRI signal with and without the magnet was observed. On the other side, sample C6S was efficiently delivered to the tumor tissue, with a three-fold T2-MRI contrast enhancement upon the external magnet application. The effective magnetic targeting of C6S capsules was also confirmed by the reduction in T2-MRI contrast in spleen if compared with the untreated with magnet mice values, and the presence of dense and clustered iron aggregates in tumor histology sections even 48 h after the magnetic targeting.Conclusion: The highlighted strategy of magnetic biodegradable polyelectrolyte capsules' design allows for the development of an efficient drug delivery system, which through an MRI-guided externally controlled navigation may lead to a significant improvement of the anticancer chemotherapy performance.

Biodegradable polyelectrolyte complexes of chitosan and partially crosslinked dextran phosphate with potential for biomedical applications

Polyelectrolyte complexes (PECs) are spontaneously formed by mixing oppositely charged polyelectrolyte solutions without the use of organic solvents and chemical crosslinkers are great candidate carriers for drug delivery. Herein, biodegradable antimicrobial polyelectrolyte complexes of chitosan – dextran phosphate (DPCS) containing cefazolin were developed and characterized in order to assess their suitability for biomedical applications. For this purpose, the simultaneous partial crosslinking and functionalization of dextran with phosphoric acid in a urea melt under reduced pressure were studied. The functional group content and molecular weight of dextran phosphate were varied in order to establish their influence on gel fraction yield, thermal properties and morphologies of the hydrogels. The stoichiometric PECs of DPCS showed good in vitro biocompatibility, pH sensitivity and biodegradability depending on the hydrogel composition. The release of drug from cefazolin-loaded DPCS hydrogels was through non-Fickian diffusion and displayed long sustained-release time. The drug-loaded hydrogels showed antimicrobial activity against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. The tunable degradation behavior under physiological conditions in combination with biocompatibility of the pristine DPCS and high antibacterial efficacy drug-loaded hydrogels may render the presented materials interesting for biomedical applications.

Effective Detection of Nafion®-Based Theranostic Nanocapsules through 19F Ultra-Short Echo Time MRI.

The application of the Three-Dimensional Ultra-Short Echo Time (3D UTE)pulse sequence at a high magnetic field for visualization of the distribution of 19F loaded theranostic core-shell nanocapsules with Nafion® (1,1,2,2-tetrafluoroethene; 1,1,2,2-tetrafluoro-2- [1,1,1,2,3,3-hexafluoro-3-(1,2,2-trifluoroethenoxy)propan-2-yl] oxyethanesulfonic acid) incorporated into the shell is presented. The nanocarriers were formed via the layer-by-layer technique with biodegradable polyelectrolytes: PLL (Poly-L-lysine), and with Nafion®: polymer with high 19F content. Before imaging, an MR (magnetic resonance) spectroscopy and T1 and T2 measurements were performed, resulting in values of T2 between 1.3 ms and 3.0 ms, depending on the spectral line. To overcome limitations due to such short T2, the 3D UTE pulse sequence was applied for 19F MR imaging. First Nafion® solutions of various concentrations were measured to check the detection limit of our system for the investigated molecule. Next, the imaging of a phantom containing core-shell nanocapsules was performed to assess the possibility of visualizing their distribution in the samples. Images of Nafion® containing samples with SNR ≥ 5 with acquisition time below 30 min for 19F concentration as low as 1.53 × 10−2 mmol 19F/g of sample, were obtained. This is comparable with the results obtained for molecules, which exhibit more preferable MR characteristics.

Development and characterization of layer-by-layer coated liposomes with poly(L-lysine) and poly(L-glutamic acid) to increase their resistance in biological media.

Multilayered coated liposomes were prepared using the layer-by-layer (LbL) technique in an effort to improve their stability in biological media. The formulation strategy was based on the alternate deposition of two biocompatible and biodegradable polyelectrolytes - poly(L-lysine) (PLL) and poly(L-glutamic acid) (PGA) - on negatively charged small unilamellar vesicles (SUVs). Some parameters of the formulation process were optimized such as the polyelectrolyte concentration and the purification procedure. This optimized procedure has allowed the development of very homogeneous formulations of liposomes coated with up to 6 layers of polymers (so-called layersomes). The coating was characterized by dynamic light scattering (DLS), zeta potential measurements and Förster resonance energy transfer (FRET) between two fluorescently labeled polyelectrolytes. Studies on the stability of the formulations at 4°C in a buffered solution have shown that most structures are stable over 1month without impacting their encapsulation capacity. In addition, fluorophore release experiments have demonstrated a better resistance of the layersomes in the presence of a non-ionic detergent (Triton™ X-100) as well as in the presence of phospholipase A2 and human plasma. In conclusion, new multilayered liposomes have been developed to increase the stability of conventional liposomes in biological environments.

Polymeric Core-Shell Nanoparticles Prepared by Spontaneous Emulsification Solvent Evaporation and Functionalized by the Layer-by-Layer Method.

The aim of our study was to develop a novel method for the preparation of polymeric core-shell nanoparticles loaded with various actives for biomedical applications. Poly(caprolactone) (PCL), poly(lactic acid) (PLA) and poly(lactide-co-glycolide) (PLGA) nanoparticles were prepared using the spontaneous emulsification solvent evaporation (SESE) method. The model active substance, Coumarin-6, was encapsulated into formed polymeric nanoparticles, then they were modified/functionalized by multilayer shells’ formation. Three types of multilayered shells were formed: two types of polyelectrolyte shell composed of biocompatible and biodegradable polyelectrolytes poly-L-lysine hydrobromide (PLL), fluorescently-labeled poly-L-lysine (PLL-ROD), poly-L-glutamic acid sodium salt (PGA) and pegylated-PGA (PGA-g-PEG), and hybrid shell composed of PLL, PGA, and SPIONs (superparamagnetic iron oxide nanoparticles) were used. Multilayer shells were constructed by the saturation technique of the layer-by-layer (LbL) method. Properties of our polymeric core-shell nanoparticle were optimized for bioimaging, passive and magnetic targeting.

Biodegradable Nanocarriers Resembling Extracellular Vesicles Deliver Genetic Material with the Highest Efficiency to Various Cell Types.

Efficient delivery of genetic material to primary cells remains challenging. Here, efficient transfer of genetic material is presented using synthetic biodegradable nanocarriers, resembling extracellular vesicles in their biomechanical properties. This is based on two main technological achievements: generation of soft biodegradable polyelectrolyte capsules in nanosize and efficient application of the nanocapsules for co-transfer of different RNAs to tumor cell lines and primary cells, including hematopoietic progenitor cells and primary T cells. Near to 100% efficiency is reached using only 2.5 × 10-4 pmol of siRNA, and 1 × 10-3 nmol of mRNA per cell, which is several magnitude orders below the amounts reported for any of methods published so far. The data show that biodegradable nanocapsules represent a universal and highly efficient biomimetic platform for the transfer of genetic material with the utmost potential to revolutionize gene transfer technology in vitro and in vivo.

Gadolinium labeled polyelectrolyte nanocarriers for theranostic application

Here, we designed a novel Gadolinium (Gd) labeled drug-loaded polyelectrolyte nanocarriers for theranostics. The nanocarriers were formed via layer-by-layer technique with biodegradable polyelectrolytes: PLL (Poly-L-lysine), PLL-Gd (Gadolinium-labeled Poly-L-lysine) and PGA (Poly-L-glutamic acid). Anticancer drug (Paclitaxel) was encapsulated in the formed nanocarriers. The average size of synthesized nanocarriers was around 150 nm. The empty gadolinium labeled nanocarriers did not show any deleterious effects on tested cells (CT26-CEA, B16F10, 4T1 and PBMC), whereas encapsulated paclitaxel retained its cytotoxic/cytostatic activity. Using T2 and T1 NMR relaxation measurements with 9.4 T preclinical MRI scanner, we demonstrated that gadolinium labeled nanocarriers can be detected due to a locally altered contrast in the MR image. Thus, they may become a promising platform for future theranostic applications.

Doxorubicin-loaded biodegradable capsules: Temperature induced shrinking and study of cytotoxicity in vitro

Doxorubicin (DOX) is one of mainstays in anticancer therapy due to its universal anticancer activity. Development of DOX delivery systems is of particular importance aiming a reduction in its non-targeted toxicity and improvement of the treatment efficiency. In this study, biodegradable polyelectrolyte multilayer capsules from a dextran sulfate (DS) and poly-l-arginine (Parg) couple for intracellular DOX delivery has been developed. The capsules were fabricated by layer-by-layer (LbL) technique using vaterite particles (500±100nm) as sacrificial templates. An elegant approach for simultaneous miniaturization of the capsules down to a size of 290±60nm and DOX loading was elaborated. Cytotoxicity of the DOX-loaded capsules was evaluated in vitro using human breast adenocarcinoma MCF-7 and DOX-resistant MCF-7/ADR cells. Penetration and accumulation of the capsules in the cells were studied by confocal microscopy and flow cytometry. The pronounced accumulation of the DOX-loaded shrunken capsules in MCF-7/ADR cells suggested overcoming drug resistance. The developed capsules could be promising for both anticancer therapy and diagnostic purposes.

Emerging biomedical applications of polyaspartic acid-derived biodegradable polyelectrolytes and polyelectrolyte complexes.

Polyelectrolytes (PELs) - polymers with charged repeat units - have emerged as a useful class of polymers for biomedical applications due to their high aqueous solubility, low aggregation propensity and the opportunity they afford for polyvalent interactions with surfaces. Biodegradability and biocompatibility of PELs are important prerequisites for their utilization in in vivo applications. PELs that can be chemically functionalized with ease prove advantageous for creating diverse biomaterials. Polyaspartic acid (PASA) is a modular and biocompatible synthetic PEL that has all these features. It also shows many positive biomedical attributes such as bone-tissue targeting, muco-adhesive behavior and extended blood circulation time. Cationic PELs derived from PASA are rapidly internalized by mammalian and bacterial cells, and hence have immense utility in therapeutic delivery applications. Polyelectrolyte complexes (PECs) and multilayers (PEMs) formed from PASA PELs have further expanded their biomedical utility. This mini-review highlights some recent literature examples of unique biomedical applications of PELs, PECs and PEMs prepared through the molecular engineering of PASA. It discusses biomineralization modulators, anti-mycobacterial agents, underwater adhesives, mucoadhesive drug and gene delivery agents, and cell encapsulants fabricated using PASA derived PELs.

Thermo-Induced Shrinking of “Dextran Sulfate/Polyarginine” Capsules with Magnetic Nanoparticles in the Shell

Polyelectrolyte capsules consisting of a combination of biodegradable polyelectrolytes, dextran sulfate/polyarginine, and magnetic nanoparticles have been prepared. The possibility of changing the sizes and morphology of the capsules by heating their aqueous suspension has been investigated. The efficiency of capsule shrinking doesn’t change when a layer of magnetic nanoparticles is introduced into the shell. The nanoparticles are uniformly distributed in the shell and do not aggregate during the process of its rearrangement under the influence of temperature.

Polylactic acid sealed polyelectrolyte complex microcontainers for controlled encapsulation and NIR-Laser based release of cargo.

Surface mediated drug delivery is important for a large variety of applications, especially in medicine to control cell growth, prevent blood platelet activation on implants or for self-disinfecting devices (e.g. catheters). In industrial applications, controlled release of substances from surfaces is needed in a broad range of applications from anti-corrosion systems to anti-biofouling. Polyelectrolyte multilayers (PEM) based microcontainers (MCs) require several days production time, while MCs composed out of polylactic acid (PLA) are entirely hydrophobic, offering no functionality. We hereby present an approach to fabricate PLA coated synthetic as well as biopolymer based biodegradable polyelectrolyte complex MCs able to encapsulate small hydrophilic cargo within less than one hour. The chambers facilitate laser controlled release of cargo within submerged conditions.