Search Results (138)

The formation of beta-lactoglobulin (BLG)/sodium polystyrene sulfonate (PSS) complexes decelerates the change in the surface properties of the mixed solutions with the surface age and increases the steady-state dilational surface elasticity in a narrow PSS concentration range. At the same time, the changes in the surface properties are accelerated in the dispersions of BLG fibrils with and without PSS due to the influence of small peptides coexisting with fibrils. A decrease in the peptide concentration as a result of the dispersion purification leads to slower changes in the surface properties at low PSS concentrations. The increase in the polyelectrolyte concentration results in an increase in the steady-state surface elasticity due to the fibril/PSS complex formation and in very slow changes in the surface properties if the polyelectrolyte exceeds a certain critical value. The latter effect is a consequence of the formation of large aggregates and of an increase in the electrostatic adsorption barrier. The consecutive adsorption of BLG fibrils and PSS leads to the formation of regular multilayers at the liquid–gas interface. The multilayer properties change noticeably with an increase in the number of layers from four to six in agreement with previous results on the multilayers of PSS with an oppositely charged synthetic polyelectrolyte, presumably due to the heterogeneity of the first PSS layer. The dynamic elasticity of the multilayers approaches 250 mN/m, indicating that they can effectively stabilize foams and emulsions. Full article

Three-dimensional printing (3DP) has emerged as a promising method for creating intricate scaffold designs. This study assessed three 3DP scaffold designs fabricated using biodegradable poly(lactic) acid (PLA) through fused deposition modelling (FDM): mesh, two channels (2C), and four channels (4C). To address the limitations of PLA, such as hydrophobic properties and poor cell attachment, a post-fabrication modification technique employing Polyelectrolyte Multilayers (PEMs) coating was implemented. The scaffolds underwent aminolysis followed by coating with SiCHA nanopowders dispersed in hyaluronic acid and collagen type I, and finally crosslinked the outermost coated layers with EDC/NHS solution to complete the hybrid scaffold production. The study employed rotating wall vessels (RWVs) to investigate how simulating microgravity affects cell proliferation and differentiation. Human mesenchymal stem cells (hMSCs) cultured on these scaffolds using proliferation medium (PM) and osteogenic media (OM), subjected to static (TCP) and dynamic (RWVs) conditions for 21 days, revealed superior performance of 4C hybrid scaffolds, particularly in OM. Compared to commercial hydroxyapatite scaffolds, these hybrid scaffolds demonstrated enhanced cell activity and survival. The pre-vascularisation concept on 4C hybrid scaffolds showed the proliferation of both HUVECs and hMSCs throughout the scaffolds, with a positive expression of osteogenic and angiogenic markers at the early stages. Full article

Controlling cell adhesion, viability, and proliferation on solid surfaces is critical for the successful implantation and proper functioning of temporary and permanent medical devices. While, with temporary or removable implants as well as surgical instruments, even slight cellular adhesion leads to an increased risk of secondary infections, bleeding and other complications, good cellular adhesion and viability are essential for the rapid healing and successful integration of permanent implants. This work was motivated by the growing interest in the construction of biocompatible and biodegradable coatings for the biofunctionalization of medical devices. Polysaccharide-based coatings are well known for their biocompatibility, but they are non-cell-adhesive, which hinders their application as implant coatings. In this study, we demonstrate that the incorporation of one or more graphene oxide layers in hyaluronic acid/chitosan multilayers is one avenue to regulate the degree of unspecific adhesion and growth of different cells (human umbilical vein endothelial cells, HUVEC, and mouse embryonic fibroblasts, 3T3). Furthermore, we demonstrate that this approach allows cell adhesion to be regulated across the entire range between completely prevented and highly promoted cell adhesion without introducing systemic cytotoxicity. These findings may contribute to the establishment of a new approach to adapt medical devices to cells and tissues. Full article

Water scarcity and contamination have emerged as critical global challenges, requiring the development of effective and sustainable solutions for the treatment of contaminated water. Recently, functionalized polymer biomaterials have garnered significant interest because of their potential for a wide range of water treatment applications. Accordingly, this paper highlights the design of a new adsorbent material based on a cellulosic nonwoven textile grafted with two extracted biopolymers. The layer-by-layer grafting technique was used for the polyelectrolyte multi-layer (PEM) biosorbent production. Firstly, we extracted a Suaeda fruticosa polysaccharide (SFP) and confirmed its pectin-like polysaccharide structure via SEC, NMR spectroscopy, and chemical composition analyses. Afterward, the grafting was designed via an alternating multi-deposition of layers of SFP polymer and carrageenan crosslinked with 1,2,3,4-butanetetracarboxylic acid (BTCA). FT-IR and SEM were used to characterize the chemical and morphological characteristics of the designed material. Chemical grafting via polyesterification reactions of the PEM biosorbent was confirmed through FT-IR analysis. SEM revealed the total filling of material microspaces with layers of grafted biopolymers and a rougher surface morphology. The assessment of the swelling behavior revealed a significant increase in the hydrophilicity of the produced adsorbent system, a required property for efficient sorption potential. The evaluation of the adsorption capabilities using the methylene blue (MB) as cationic dye was conducted in various experimental settings, changing factors such as the pH, time, temperature, and initial concentration of dye. For the untreated and grafted materials, the greatest adsorbed amounts of MB were 130.6 mg/g and 802.6 mg/g, respectively (pH = 4, T = 22 C, duration = 120 min, and dye concentration = 600 mg/L). The high adsorption performance, compared to other reported materials, was due to the presence of a large number of hydroxyl, sulfonate, and carboxylic functional groups in the biosorbent polymeric system. The adsorption process fitted well with the pseudo-first-order kinetic model and Langmuir/Temkin adsorption isotherms. This newly developed multi-layered biosorbent shows promise as an excellent adsorption resultant and cheap-cost/easy preparation alternative for treating industrial wastewater. Full article

The application of titanium nitride (TiN) as an electrode for electrochemical deposition or characterization requires the removal of an insulating layer from its surface. This process was studied and optimized, and the conditions for the complete removal of this layer through treatment with oxalic acid were formulated. The obtained TiN surfaces were used for the deposition of various conducting and non-conducting polymers. Two different approaches were applied: (i) in situ electrochemical synthesis of the main classes of conducting polymers, including polyaniline, polypyrrole, polythiophene, and selected derivatives thereof, and (ii) electrostatically driven layer-by-layer (LbL) deposition of multilayers of oppositely charged polyelectrolytes. The deposited polymers were characterized by electrochemical methods. The electrochemical properties of the deposited conducting polymers and their deposition on the TiN surface were comparable to those of the metallic electrodes. The films produced via LbL deposition exhibited a pronounced influence of the charge of the last deposited polymer on the redox reaction of ferri/ferrocyanide, validating the charge alteration with each successive polymer layer deposition. The studied deposition technologies can be used for the modification of TiN surfaces required in applications of this material in chemical sensors and other devices. Full article

Immunosensors based on field-effect transistors with nanowire channels (NWFETs) provide fast and real-time detection of a variety of biomarkers without the need for additional labels. The key feature of the developed immunosensor is the coating of silicon NWs with multilayers of polyelectrolytes (polyethylenimine (PEI) and polystyrene sulfonate (PSS)). By causing a macromolecular crowding effect, it ensures the “soft fixation” of the antibodies into the 3-D matrix of the oppositely charged layers. We investigated the interaction of prostate-specific antigen (PSA), a biomarker of prostate cancer, and antibodies adsorbed in the PEI and PSS matrix. In order to visualize the formation of immune complexes between polyelectrolyte layers using SEM and AFM techniques, we employed a second clone of antibodies labeled with gold nanoparticles. PSA was able to penetrate the matrix and concentrate close to the surface layer, which is crucial for its detection on the nanowires. Additionally, this provides the optimal orientation of the antibodies’ active centers for interacting with the antigen and improves their mobility. NWFETs were fabricated from SOI material using high-resolution e-beam lithography, thin film vacuum deposition, and reactive-ion etching processes. The immunosensor was characterized by a high sensitivity to pH (71 mV/pH) and an ultra-low limit of detection (LOD) of 0.04 fg/mL for PSA. The response of the immunosensor takes less than a minute, and the measurement is carried out in real time. This approach seems promising for further investigation of its applicability for early screening of prostate cancer and POC systems. Full article

Degradable layer-by-layer (LbL) polymeric coatings have distinct advantages over traditional biomedical coatings due to their precision of assembly, versatile inclusion of bioactive molecules, and conformality to the complex architectures of implantable devices. However, controlling the degradation rate while achieving biocompatibility has remained a challenge. This work employs polyphosphazenes as promising candidates for film assembly due to their inherent biocompatibility, tunability of chemical composition, and the buffering capability of degradation products. The degradation of pyrrolidone-functionalized polyphosphazenes was monitored in solution, complexes and LbL coatings (with tannic acid), providing the first to our knowledge comparison of solution-state degradation to solid-state LbL degradation. In all cases, the rate of degradation accelerated in acidic conditions. Importantly, the tunability of the degradation rate of polyphosphazene-based LbL films was achieved by varying film assembly conditions. Specifically, by slightly increasing the ionization of tannic acid (near neutral pH), we introduce electrostatic “defects” to the hydrogen-bonded pairs that accelerate film degradation. Finally, we show that replacing the pyrrolidone side group with a carboxylic acid moiety greatly reduces the degradation rate of the LbL coatings. In practical applications, these coatings have the versatility to serve as biocompatible platforms for various biomedical applications and controlled release systems. Full article

Polyelectrolyte multilayers (PEMs) deposited on porous composite polylactic acid/poly(ε-caprolactone) (PDLA/PEC) substrates were studied. The substrates were previously charged in a corona discharge. Time dependences of the normalized surface potential for positively and negatively charged electrets were investigated. The morphology of the obtained porous substrates was examined by means of scanning electron microscopy (SEM). The chitosan and the casein polyelectrolytes were deposited on the substrates using the layer-by-layer (LbL) technique. The drug loading efficiency and the release kinetics were determined spectrophotometrically. Full article

In recent decades, there has been increased attention to the role of layer-by-layer assembled bio-polymer 3D structures (capsules, beads, and microgels) for biomedical applications. Such free-standing multilayer structures are formed via hard templating onto sacrificial cores such as vaterite CaCO₃ crystals. Immobilization of these structures onto solid surfaces (e.g., implants and catheters) opens the way for the formulation of advanced bio-coating with a patterned surface. However, the immobilization step is challenging. Multiple approaches based mainly on covalent binding have been developed to localize these multilayer 3D structures at the surface. This work reports a novel strategy to formulate multilayer surface-supported microgels (ss-MG) directly on the surface via hard templating onto ss-CaCO₃ pre-grown onto the surface via the direct mixing of Na₂CO₃ and CaCl₂ precursor solutions. ss-MGs were fabricated using biopolymers: polylysine (PLL) as polycation and three polyanions—hyaluronic acid (HA), heparin sulfate (HS), and alginate (ALG). ss-MG biodegradation was examined by employing the enzyme trypsin. Our studies indicate that the adhesion of the ss-MG to the surface and its formation yield directly correlate with the mobility of biopolymers in the ss-MG, which decreases in the sequence of ALG > HA > HS-based ss-MGs. The adhesion of HS-based ss-MGs is only possible via heating during their formation. Dextran-loading increases ss-MG formation yield while reducing ss-MG shrinking. ss-MGs with higher polymer mobility possess slower biodegradation rates, which is likely due to diffusion limitations for the enzyme in more compact annealed ss-MGs. These findings provide valuable insights into the mechanisms underlying the formation and biodegradation of surface-supported biopolymer structures. Full article

Bacterial infections are a common mode of failure for medical implants. This study aims to develop antibacterial polyelectrolyte multilayer (PEM) coatings that contain a plant-derived condensed tannin polymer (Tanfloc, TAN) with inherent antimicrobial activity. Tanfloc is amphoteric, and herein we show that it can be used as either a polyanion or a polycation in PEMs, thereby expanding the possibility of its use in PEM coatings. PEMs are ordinarily formed using a polycation and a polyanion, in which the functional (ionic) groups of the two polymers are complexed to each other. However, using the amphoteric polymer Tanfloc with weakly basic amine and weakly acidic catechol and pyrogallol groups enables PEM formation using only one or the other of its functional groups, leaving the other functional group available to impart antibacterial activity. This work demonstrates Tanfloc-containing PEMs using multiple counter-polyelectrolytes including three polyanionic glycosaminoglycans of varying charge density, and the polycations N,N,N-trimethyl chitosan and polyethyleneimine. The layer-by-layer (LbL) assembly of PEMs was monitored using in situ Fourier-transform surface plasmon resonance (FT-SPR), confirming a stable LbL assembly. X-ray photoelectron spectroscopy (XPS) was used to evaluate surface chemistry, and atomic force microscopy (AFM) was used to determine the surface roughness. The LDH release levels from cells cultured on the Tanfloc-containing PEMs were not statistically different from those on the negative control (p > 0.05), confirming their non-cytotoxicity, while exhibiting remarkable antiadhesive and bactericidal properties against Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus), respectively. The antibacterial effects were attributed to electrostatic interactions and Tanfloc’s polyphenolic nature. This work underscores the potential of Tanfloc as a versatile biomaterial for combating infections on surfaces. Full article

Bioactive surface coatings have retained the attention of researchers and physicians due to their versatility and range of applications in orthopedics, particularly in infection prevention. Antibacterial metal nanoparticles (mNPs) are a promising therapeutic, with vast application opportunities on orthopedic implants. The current research aimed to construct a polyelectrolyte multilayer on a highly porous titanium implant using alternating thin film coatings of chitosan and alginate via the layer-by-layer (LbL) self-assembly technique, along with the incorporation of silver nanoparticles (AgNPs) or titanium dioxide nanoparticles (TiO₂NPs), for antibacterial and osteoconductive activity. These mNPs were characterized for their physicochemical properties using quartz crystal microgravimetry with a dissipation system, nanoparticle tracking analysis, scanning electron microscopy, and atomic force microscopy. Their cytotoxicity and osteogenic differentiation capabilities were assessed using AlamarBlue and alkaline phosphatase (ALP) activity assays, respectively. The antibiofilm efficacy of the mNPs was tested against Staphylococcus aureus. The LbL polyelectrolyte coating was successfully applied to the porous titanium substrate. A dose-dependent relationship between nanoparticle concentration and ALP as well as antibacterial effects was observed. TiO₂NP samples were also less cytotoxic than their AgNP counterparts, although similarly antimicrobial. Together, these data serve as a proof-of-concept for a novel coating approach for orthopedic implants with antimicrobial and osteoconductive properties. Full article

Hydrogels can be considered as mimics of the extracellular matrix (ECM). Through integrins, the cytoskeleton is connected to the ECM, and cytoskeleton tension depends on ECM stiffness. A number of age-related diseases depend on cellular processes related to cytoskeleton function. Some examples of cancer initiation and progression and heart disease in relation to ECM stiffness have been analyzed. The incorporation of rigid particles into the ECM can increase ECM stiffness and promote the formation of internal residual stresses. Water migration, changes in water binding energy to biomactomolecules, and changes in the state of water from tightly bound water to free and loosely bound water lead to changes in the stiffness of the ECM. Cardiac tissue engineering, ECM stiffness and cancer, the equivalence of ECM stiffness, oxidative stress, inflammation, multi-layer polyelectrolyte complex hydrogels and bioprinting, residual internal stresses, viscoelastic hydrogels, hydrogel nanocomposites, and the effect of water have been reported. Special attention has been paid to the role of bound water and internal stresses in ECM stiffness. The risks related to rigid particle incorporation into the ECM have been discussed. The potential effect of polyphenols, chitosan, and chitosan oligosaccharide on ECM stiffness and the potential for anti-TNF-α and anti-NF-κB therapies have been discussed. Full article

The in situ synthesis of Fe⁰ particles using poly-(acrylic acid) (PAA) is an effective tool for fabricating catalytic membranes relevant to advanced oxidation processes (AOPs). Through their synthesis in polyelectrolyte multilayer-based nanofiltration membranes, it becomes possible to reject and degrade organic micropollutants simultaneously. In this work, we compare two approaches, where Fe⁰ nanoparticles are synthesized in or on symmetric multilayers and asymmetric multilayers. For the membrane with symmetric multilayers (4.0 bilayers of poly (diallyldimethylammonium chloride) (PDADMAC)/PAA), the in situ synthesized Fe⁰ increased its permeability from 1.77 L/m²/h/bar to 17.67 L/m²/h/bar when three Fe²⁺ binding/reducing cycles were conducted. Likely, the low chemical stability of this polyelectrolyte multilayer allows it to become damaged through the relatively harsh synthesis. However, when the in situ synthesis of Fe⁰ was performed on top of asymmetric multilayers, which consist of 7.0 bilayers of the very chemically stable combination of PDADMAC and poly(styrene sulfonate) (PSS), coated with PDADMAC/PAA multilayers, the negative effect of the Fe⁰ in situ synthesized can be mitigated, and the permeability only increased from 1.96 L/m²/h/bar to 2.38 L/m²/h/bar with three Fe²⁺ binding/reducing cycles. The obtained membranes with asymmetric polyelectrolyte multilayers exhibited an excellent naproxen treatment efficiency, with over 80% naproxen rejection on the permeate side and 25% naproxen removal on the feed solution side after 1 h. This work demonstrates the potential of especially asymmetric polyelectrolyte multilayers to be effectively combined with AOPs for the treatment of micropollutants (MPs). Full article

The increasing demand for nanofiltration processes in drinking water treatment, industrial separation and wastewater treatment processes has highlighted several shortcomings of current state-of-the-art thin film composite (TFC NF) membranes, including limitations in chemical resistance, fouling resistance and selectivity. Polyelectrolyte multilayer (PEM) membranes provide a viable, industrially applicable alternative, providing significant improvements in these limitations. Laboratory experiments using artificial feedwaters have demonstrated selectivity an order of magnitude higher than polyamide NF, significantly higher fouling resistance and excellent chemical resistance (e.g., 200,000 ppmh chlorine resistance and stability over the 0–14 pH range). This review provides a brief overview of the various parameters that can be modified during the layer-by-layer procedure to determine and fine-tune the properties of the resulting NF membrane. The different parameters that can be adjusted during the layer-by-layer process are presented, which are used to optimize the properties of the resulting nanofiltration membrane. Substantial progress in PEM membrane development is presented, particularly selectivity improvements, of which the most promising route seems to be asymmetric PEM NF membranes, offering a breakthrough in active layer thickness and organic/salt selectivity: an average of 98% micropollutant rejection coupled with a NaCl rejection below 15%. Advantages for wastewater treatment are highlighted, including high selectivity, fouling resistance, chemical stability and a wide range of cleaning methods. Additionally, disadvantages of the current PEM NF membranes are also outlined; while these may impede their use in some industrial wastewater applications, they are largely not restrictive. The effect of realistic feeds (wastewaters and challenging surface waters) on PEM NF membrane performance is also presented: pilot studies conducted for up to 12 months show stable rejection values and no significant irreversible fouling. We close our review by identifying research areas where further studies are needed to facilitate the adoption of this notable technology. Full article

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. Full article