Polyelectrolyte Bilayers Research Articles

Electronic Conductance of Nano Composite Polymer Single Walled Nanotube with Spin Spray Variant

We have studied electronic conductance of nano composite polymer single walled nanotube with spin spray variant by using layer by layer technique. The study showed that there existed a critical number of polyelectrolyte bilayer below which the electronic conductance of the material was negligible. The sheet conductance increased above the critical value. This indicated that the material conductivity was controlled by the formation of a percolating network of highly conducting nanotubes in an insulating polymetric matrix. We have presented the dependence of junction resistance on the layer separation leaded to the logarithmic behavior. The quasi two dimensional model treated the nanotube as infinitely conducting rods with resistive junctions. A junction was formed when projections of two nanotubes on the plane of the material intersect. The junction resistance increased with inter layer separation. The results found were compared with previous results and were found in good agreement

Construction of Ag-mediated organic-inorganic phosphorus-hybrid coating for flame-retardant and antibacterial cotton fabrics

Cotton fabrics (CF) with high flame retardancy and antibacterial performance are attracting more and more attention in the practical applications, e.g. home decorations. In this work, a novel Ag-mediated organic-inorganic phosphorus-hybrid coating (5BL/Ag-D) was developed using polyethylene imine (PEI)/ammonium polyphosphate (APP) polyelectrolyte bilayer and Ag-phosphoryl triazole complex (AgD) via dip-coating method for flame-retardant CF with the antibacterial property. Interestingly, limiting oxygen index (LOI) of CF/5BL/Ag-D was sharply promoted to 33.5 % from 18.6 % of CF. Besides, CF/5BL/Ag-D could self-extinguish in the vertical burning test with afterflame time and afterglow time as low as 0 s. More importantly, as revealed in the cone calorimeter tests (CCT), the heat release involving peak heat release rate (PHRR) and total heat release (THR) of CF/5BL/Ag-D decreased from 193.8 kW/m2 and 14.8 MJ/m2 of CF to merely 16.7 kW/m2 and 3.2 MJ/m2, respectively. In addition, owing to the presence of Ag+, CF/5BL/Ag-D was endowed with the desired antibacterial property, and the bacteriostatic rates of CF/5BL/Ag-D on escherichia coli (E. coli) and staphylococcus aureus (S. aureus) were up to 94.7 % and 95.1 %, respectively. Moreover, the softness, the whiteness and the mechanical properties of CF/5BL/Ag-D were comparable to those of CF. In general, this work provides a promising approach to prepare Ag-mediated organic-inorganic phosphorus-hybrid coating for multifunctional cotton fabrics.

Large-scale plasmonic nanodisk array as a biosensing platform fabricated by transfer nanoprinting.

Surface plasmon resonance based on nanostructures has been a powerful analytical tool in rapid detection and analysis of biomolecules. However, the fabrication of nanostructure sensors, such as electron beam lithography and focused ion beam milling, has inherent defects as manufacturing cost, complex process flow, and small fabrication area. In this paper, using the transfer nanoprinting approach based on an ultrathin anodic aluminum oxide membrane, a centimeter-scale ordered periodic Ag-ZnS bilayer nanodisk on Au film with a low cost and simple process is fabricated. A surface plasmon polariton Bloch mode from nanodisk arrays is experimentally demonstrated at normal incident of light. The plasmonic platform exhibits an ideal refractive index bulk sensitivity of up to 438nm/RIU. Furthermore, by using a polyelectrolyte bilayer with well-defined thickness, the surface sensitivity of the biosensing platform is also investigated. The large-scale plasmonic bilayer nanoparticle biosensing platform has broad application prospects in development of low-cost and high-performance biosensing chips.

Molecular Structure Engineering of Polyelectrolyte Bilayer-Based Memristors: Implications for Linear Potentiation and Depression Characteristics

Critical to artificial intelligence’s future is emulating biological synapses with memristors. Moreover, according to a wide variety, low cost, simple fabrication, and good flexibility, organic materials provide a competitive approach in memristor and synapse emulation, especially in devices where ions carry current. Polyelectrolytes with different molecular structures were used as functional layers in this study to enhance the memory and synapse performance of polyelectrolyte bilayer-based memristors, performed by ions, and polyelectrolyte chain migration caused a potential drop change at the interface of the ∼15 nm thick polyelectrolyte bilayer and its electrodes. Consequently, the memory device with strong polyelectrolyte sodium poly(styrene sulfonic acid) (PSS) and poly(diallyl dimethylammonium chloride) (PDAC), which were prepared by spin-coating, shows outstanding resistive switching performance and synapse functionalities than those with weak polyelectrolytes and/or polyelectrolytes without a ring structure. Particularly, the indium tin oxide (ITO)/PSS/PDAC/ITO device shows almost linear potentiation and depression characteristics by applying continuous pulse voltage, which results in high performance on the artificial neural network simulation as 90% on the Mixed National Institute of Standards and Technology data set. The steric hindrance between the two polyelectrolytes with the five-ring structure can be attributed to the causation of linear conductance update. Furthermore, it shows short- and long-term plasticity during potentiation and depression, which is essential for the development of neuromorphic systems with complex cognitive capabilities.

Enhanced Ionic Current Rectification through Innovative Integration of Polyelectrolyte Bilayers and Charged-Wall Smart Nanochannels

The tools utilized by humans continue to shrink and speed up. Lab-on-a-chip (LOC) is one of the most recent techniques for decreasing the size of chemical systems. Today, LOCs have made substantial strides in developing nanomaterial fabrication techniques. Controlling and regulating the fluid and ion mobility in these systems is crucial. Layer-by-layer (LBL) soft layers are one of the most effective strategies for controlling fluid flow in channels. In light of the present constraints for developing these systems and the high expense of experimental investigations, it is vital to employ modeling to minimize costs and comprehend their underlying ideas and operations. In this study, we examined the influence of the LBL soft layer's presence in the charged nanochannels on the ion transport parameters. To examine the effect of the coating length of the LBL soft layer, we first examined three lengths of coating: one with a length greater than half (type (I)), one with a length equal to half (type (II)), and one with a length less than half (type (III)) of the nanochannel length. Then, by solving Poisson-Nernst-Planck and Navier-Stokes equations, we determined the influences of pH, soft layer charge density (NPEL/NA), bulk concentration (C0), and hard surface charge density (σ) on the ionic current rectification (Rf) and selectivity (S) of the nanochannel. The maximum rectification of 30.65 was achieved using a nanochannel of type (III) and σ = +10 mC/m2. The current results demonstrate a promising hybrid architecture consisting of an LBL soft layer and a smart charged nanochannel for enhanced rectification.

Fabrication and Characterization of Eco-Friendly Polyelectrolyte Bilayer Films Based on Chitosan and Different Types of Edible Citrus Pectin.

The eco-friendly polyelectrolyte bilayer films were prepared by layer-by-layer (LBL) casting method using chitosan (CS) and four types of edible citrus pectin as film substrates. The results showed that the polyelectrolyte bilayer films exhibited excellent comprehensive properties. Furthermore, the interaction between CS and pectin was closely related to the degree of methyl-esterification (DM), molecular weight (Mw), and zeta potential of pectin. The low DM, Mw, and high zeta potential of the low methyl-esterified pectin (LM) resulted in a denser internal structure of the bilayer film, stronger UV shielding performance, and stronger gas barrier ability. The high DM and Mw of the high methyl-esterified pectin (HM) endow the bilayer film with stronger mechanical properties, thermal stability, and antifogging property. The microstructural and spectroscopic analysis showed that there are hydrogen bonds and electrostatic interactions between the layers. Overall, the developed CS-pectin polyelectrolyte bilayer films provided potential applications for food bioactive packaging.

Removal of antibiotics and antibiotic resistance genes by self-assembled nanofiltration membranes with tailored selectivity

Antibiotics and extracellular resistance genes (eARGs) in wastewater pose a potential threat to human health and hinder wastewater reuse. In this study, we present a facile and designable approach for fabricating selective polyelectrolyte multilayer (PEM) NF membranes and evaluated their performance in antibiotics and eARGs rejection from wastewater effluent. We fabricated PEM NF membranes by layer-by-layer assembly of two strong polyelectrolytes, poly (diallyl dimethylammonium chloride) and poly (sodium styrenesulfonate). By systematic manipulation of the polyelectrolyte coating solution and deposition cycle, we obtained an asymmetric separation layer with loose bottom layers and dense top layers. The PEM membrane took full advantage of the high permeability of the loose polyelectrolyte layer and the high selectivity of the dense polyelectrolyte layer, which exhibited superior antibiotics retention while maintaining a comparable permeability to the NF270 membrane. In addition, the fabricated membranes showed excellent removal of eARGs, and membranes terminated with polyanionic electrolytes could further enhance eARG retention through electrostatic repulsion. Overall, membranes with more than four polyelectrolyte bilayers could retain >99.9% of eARG. The results show that the selective asymmetric PEM membranes provide an efficient solution for remediation of antimicrobial resistance (AMR) in wastewater.

Polyelectrolyte Bilayer-Based Transparent and Flexible Memristor for Emulating Synapses.

Memristors will be critical components in the next generation of digital technology and artificial synapses. Researchers are investigating innovative mechanistic understanding of the memristor devices based on low-cost, solution-processable, and organic materials as promising candidates. Here, we demonstrate a novel polyelectrolyte-based memristor device, which is simply prepared by spin-coating poly(acrylic acid) (PAA) and polyethylenimine (PEI) on an indium tin oxide (ITO) substrate followed by a magnetron sputtering of the ITO as the top electrode. The device has a potential to achieve excellent resistive switching (RS) performance and synapse functionality as well as greater flexibility and transmittance when compared to the oxide-based memories. An on/off resistance ratio of 50 can be maintained without degradation for up to 20 000 cycles (flat state) and over 4000 cycles (bending to a 2 mm radius 10 000 times) in the DC sweep mode. Moreover, the device performs various synaptic functions, including spike-timing-dependent plasticity, pulse pair plasticity, and short-term and long-term plasticity in the potentiation and depression processes. The counterions and two oppositely charged polyelectrolyte chains can move in and out of each other depending on the applied electrical potential (pulse), resulting in a change in the potential drop at the interface of the polyelectrolyte bilayer and its electrodes, which can be attributed to the RS mechanism and various synaptic functions. This insight may accelerate the technological deployment of the organic resistive memories.

Open and dense hollow fiber nanofiltration membranes through a streamlined polyelectrolyte-based spinning process

Polyelectrolyte composite hollow fiber membranes show a high potential to become applied in industrial nanofiltration applications such as water purification or downstream processing in several industries. This material platform allows multiple routes to achieve tailored selectivities and high permeances. Hollow fiber membranes promise a higher process efficiency due to higher packing densities and their backwash stability. However, the fabrication of composite polyelectrolyte hollow fiber nanofiltration membranes is more challenging compared to state of the art spiral wound modules. While the Layer-by-Layer deposition has proven versatile opportunities and is recently entering the commercial market, the multi-step post-treatment is elaborate. In this work, we streamline the fabrication of polyelectrolyte composite hollow fiber membranes. We extend our recently presented ”chemistry-in-a-spinneret” approach with a membrane modification in a subsequent coating bath. The additional modification can be incorporated in the composite hollow fiber membrane manufacturing process without additional process steps. Sulfonated polyethersulfone as a polyanionic additive is used in the polymer solution which complexates with the polycations polyethylenimine (PEI) or poly(diallyldimethylammonium chloride (PDADMAC) in the bore fluid during fiber spinning. The extruded fibers have a positively charged lumen surface which allows a subsequent modification with the polyanion poly(sodium 4-styrenesulfonate) (PSS) in the coating bath. The spun fibers reveal with 16-4 LMH/bar pure water permeance (PWP) and 2000-1100 Dalton (Da) molecular weight cut-off (MWCO) open nanofiltration characteristics, while the PEI+PSS modified fibers show dense nanofiltration characteristics (0.6 LMH/bar PWP and 360 Da MWCO). The fibers are backwash stable and the PDADMAC and PDADMAC+PSS fibers show a significantly higher sodium hypochlorite (NaOCl) stability compared to the PEI and PEI+PSS fibers. This new technique creates composite hollow fiber nanofiltration membranes with a polyelectrolyte bilayer without multi-step post-treatment. Therefore, it provides a promising alternative to the Layer-by-Layer post-modification, where two coating steps and one water washing post-treatment step are required to create a polyelectrolyte bilayer on a porous hollow fiber membrane support. • Composite hollow fiber nanofiltration membranes without multi-step post-treatment. • The chemistry in a spinneret technique is extended with a polyanion coating step. • Backwash stable hollow fibers feature open or dense NF characteristics. • PDADMAC and PDADMAC+PSS show higher NaOCl stability compared to PEI and PEI+PSS. • Fibers with open NF characteristics are competitive with commercial nanofiltration membranes.

The effect of layer thickness and immobilization chemistry on the detection of CRP in LSPR assays

The immobilization of a capture molecule represents a crucial step for effective usage of gold nanoparticles in localized surface plasmon resonance (LSPR)-based bioanalytics. Depending on the immobilization method used, the resulting capture layer is of varying thickness. Thus, the target binding event takes place at different distances to the gold surface. Using the example of a C-reactive protein immunoassay, different immobilization methods were tested and investigated with regard to their resulting target signal strength. The dependency of the target signal on the distance to the gold surface was investigated utilizing polyelectrolyte bilayers of different thickness. It could be experimentally demonstrated how much the LSPR-shift triggered by a binding event on the gold nanoparticles decreases with increasing distance to the gold surface. Thus, the sensitivity of an LSPR assay is influenced by the choice of immobilization chemistry.

Origin of Ultrahigh Rectification in Polyelectrolyte Bilayers Modified Conical Nanopores.

The switching of "ON" and "OFF" states of an ionic diode is investigated by considering a conical nanopore partially functionalized two polyelectrolyte (PE) layers via layer-by-layer deposition. Through observing the inversion of its rectification behavior, we demonstrate the function of the PE bilayers in ionic transport regulation. The ionic diode exhibits an ultrahigh ion rectification at a low level of pH. In an aqueous NaCl solution at pH 2, for example, the ratio of the current at "ON" state and that at "OFF" state can be about 800 and 200 for 1 and 100 mM, respectively. This remarkable gating behavior can be explained by the anion-pump-induced ion accumulation in the neutral region as well as the depletion zone at the interface. Our results further demonstrate the possibility of achieving an ultrahigh rectification in an ionic diode having a unipolar-like configuration.

Concentration of potassium acetate solutions via sweeping gas pervaporation using TFC membranes comprising of a PDA sublayer and PEI/PAA bilayers

• TFC membranes comprising of a PDA sublayer and PEI/PAA bilayers. • Pervaporative concentration of potassium acetate solutions. • Only a sweeping air stream is needed to carry out pervaporation. Thin film composite (TFC) membranes comprising of a self-polymerized dopamine (PDA) sublayer and self-assembled polyethyleneimine/poly(acrylic acid) (PEI/PAA) bilayers were developed to concentrate aqueous potassium acetate (KAc) solutions via sweeping gas pervaporation. To have a closer look into permeation behavior of the membrane, pervaporation with aqueous solutions containing other select salts (KCl, NaAc, NaCl and MgCl 2 ) was also investigated. It was shown that the number of the polyelectrolyte bilayers could be reduced effectively by the use of a PDA sublayer in constructing the composite membranes. It was shown that the TFC membrane with a single PEI/PAA bilayer on top of the PDA sublayer was effective for pervaporative concentration of the salts, and a complete salt retention was achieved for essentially all feed solutions studied. The effects of operating conditions (i.e., temperature and feed concentration) and nature of the salt in the feed solution on the performance of the pervaporative separation were also studied, along with an analysis of activation energy for water permeation and mass transfer resistance of the membrane. It was shown that the membrane permeability to water was affected by the anions of the salts more significantly than the cations. The membrane was found stable in pervaporative concentration of the salt solutions at different concentrations and temperatures.

Enhanced monovalent over divalent cation selectivity with polyelectrolyte multilayers in membrane capacitive deionization via optimization of operational conditions

In this work, we tuned the ion selectivity of a polyelectrolyte multilayer (PEM)-coated, cation-exchange membrane (CMX) in a membrane capacitive deionization (MCDI) process by carefully studying different operational modes, namely constant voltage (CV) and constant current (CC). The monovalent cation selectivity and its time-dependent behavior were monitored at different voltage and current values. Upon optimizing the current density (10 A/m2) and the number of polyelectrolyte bilayers (5.5) on the CMX membranes, a time-independent and nearly full monovalent cation selectivity was obtained for various feed solutions, provided a polycation-terminated PEM was applied. Furthermore, the selectivity values of several commercially available cation-exchange membranes were tested under the optimized conditions and compared with CMX and PEM-CMX, yielding the best performance for PEM-CMX, regardless the composition of feed solution. Before this optimization, this MCDI system showed a time-dependent selectivity, with a maximum of ρMgNa ≈3. The results were rationalized by applying an MCDI model based on the dynamic potential profile, describing the potential drops across the membrane and demonstrating a threshold for the current density.

Functionalization of additive-manufactured Ti6Al4V scaffolds with poly(allylamine hydrochloride)/poly(styrene sulfonate) bilayer microcapsule system containing dexamethasone

Porous titanium alloy Ti6Al4V scaffolds manufactured via electron beam melting (EBM®) reveal broad prospects for applications in bone tissue engineering. However, local inflammation and even implant failure may occur while placing an implant into the body. Thus, the application of drug carriers to the surface of a metallic implant can provide treatment at the inflammation site. In this study, we propose to use polyelectrolyte (PE) microcapsules formed by layer-by-layer (LbL) synthesis loaded with both porous calcium carbonate (CaCO3) microparticles and the anti-inflammatory drug dexamethasone (DEX) to functionalize implant surfaces and achieve controlled drug release. Scanning electron microscopy indicated that the CaCO3 microparticles coated with PE bilayers loaded with DEX had a spherical shape with a diameter of 2.3 ± 0.2 μm and that the entire scaffold surface was evenly coated with the microcapsules. UV spectroscopy showed that LbL synthesis allows the manufacturing of microcapsules with 40% DEX. According to high performance liquid chromatography (HPLC) analysis, 80% of the drug was released within 24 h from the capsules consisting of three bilayers of polystyrene sulfonate (PSS) and poly(allylamine)hydrochloride (PAH). The prepared scaffolds functionalized with CaCO3 microparticles loaded with DEX and coated with PE bilayers showed hydrophilic surface properties with a water contact angle below 5°. Mouse embryonic fibroblast cells were seeded on Ti6Al4V scaffolds with and without LbL surface modification. The surface modification with LbL PE microcapsules with CaCO3 core affected cell morphology in vitro. The results confirmed that DEX had no toxic effect and did not prevent cell adhesion and spreading, thus no cytotoxic effect was observed, which will be further studied in vivo.

Defect Repair of Polyelectrolyte Bilayers Using SDS: The Action of Micelles Versus Monomers.

Defects within single, double, and triple polyelectrolyte bilayers derived from poly(sodium 4-styrenesulfonate) (PSS) and poly(diallyldimethyammonium chloride) (PDDA) have been repaired using aqueous solutions of sodium dodecyl sulfate (SDS), as evidenced by a reduction in their permeability and an increase in their permeation selectivity. In contrast to the use of monomer solutions of SDS, which were moderately effective in repairing only double and triple bilayers, micellar solutions proved highly effective for all three assemblies. Evidence for intact micelles or micellar fragments being deposited on the surface of single bilayers of PSS/PDDA has been obtained from a combination of atomic force microscopy, X-ray photoelectron spectroscopy, ellipsometry, and contact angle measurements. Observed CO2 permeances of ca. 200 GPU and CO2/N2 selectivities of ca. 30 for SDS-repaired, single bilayers of PSS/PDDA suggest that further development of such assemblies could have the practical potential for the separation of CO2 from N2 in the flue gas.

Molecular modeling of interfacial layer-by-layer assembly towards functionalized capsule materials.

Encapsulated nanomaterials, such as polymer-coated nanoemulsions, have highly tunable properties leading to versatile applications. A current lack of understanding of the fundamentals governing the choice of "capsule" materials (polyelectrolyte + surfactant) and its ensuing performance effectively precludes their widespread use. Computational methods can start to redress this by discovering molecule-scale attributes that significantly control the design of capsule materials tuned to fit desired properties. We use molecular dynamics (MD) to carry out the layer-by-layer (LbL) assembly of six unique polyelectrolyte bilayer systems at a surfactant-mediated interface, modeling early-stage capsule synthesis. Monolayer thickness is related to layer density and polyelectrolyte/surfactant interaction energy through polyelectrolyte molecular weight and radius of gyration, respectively, yielding a simple relationship between absorption kinetics and layer structure. For the second monolayer, faster absorption kinetics are observed for pairings of polyelectrolytes with similarly sized functional groups. Surfactants with a more delocalized charge on the head-group catalyze the build-up of ions at the interface, resulting in faster absorption kinetics and greater confinement of the encapsulated material but leading to thicker, less uniform bilayers. These relationships between capsule building block molecules and nanomaterial capsule properties provide a foundation for property prediction and rational design of optimized multi-functional capsule materials.

Preparation of multilayer polyelectrolyte ceramic membrane for water disinfection

Abstract A multilayer polyelectrolyte ceramic membrane using LbL was assembled to test the performance of water disinfection capability. The natural raw clay material (kaolin) was used as the main ceramic membrane (CM) support. The impact of the number of polyelectrolyte bilayers (2, 4, 6) on the retention of Escherichia coli was systematically investigated. Test results showed the water permeability coefficients (Lp) were 85.3 L/m2.h.bar and 69.5, 28.3, 50.1 L/m2.h.bar for pristine (CM0) and ceramic membranes with two bilayers (CM2), four bilayers (CM4), and six bilayers (CM6), respectively. Complete retention of E. coli was achieved by the multilayer polyelectrolyte ceramic membrane with four bilayers. The surface morphology of the multilayer polyelectrolyte ceramic membrane was identified by scanning electron microscopy (SEM). The results showed that the multilayer polyelectrolyte ceramic membrane can be safely applied in providing water disinfection.

Effect of number of layers and deposition time on layer-by-layer (LbL) composite forward osmosis membrane

Forward osmosis (FO) refers to the osmotic process for water transfer through a semipermeable membrane that results in the separation of water from dissolved solutes. This method has been explored due to low fouling propensity and low energy requirement since the driving force is an osmotic pressure gradient between the feed and draw solutions. This research focused on determining the optimum FO membrane by controlling the number of polyelectrolyte bilayers and deposition time of membrane for seawater desalination. Poly(diallyl-dimethylammonium chloride), PDADMAC and poly(sodium 4-styrenesulfonate), PSS were used as active monomers to generate a thin layer on the ultrafiltration membrane support through layer-by-layer (LbL) deposition method. The FO lab-scale experiment was performed by using 1.75 M of sodium sulphate (Na 2 SO 4 ) as draw solution and deionised water (DI) as feed. This research was conducted based on the different number of bilayers (5, 10, and 15 bilayers) and deposition time (5, 10, and 15 min) which affected the water flux. After the best parameters were obtained, treatment on synthetic seawater (35 g/L of NaCl) was conducted, and the results were compared with that of real seawater. Among the modified membranes, it was found that the membrane 5FO15 with 5-bilayers of polyelectrolytes and 15 min of deposition time exhibited the highest water flux (4.75 L/m 2 ∙h). The membrane exhibited a lower water flux for seawater than synthetic seawater due to the existing of other solutes which may contribute to membrane fouling. From this research, the polyelectrolyte membrane exhibited a high potential of treating seawater in Malaysia by FO process which is a good option of water treatment.

Energy barriers to anion transport in polyelectrolyte multilayer nanofiltration membranes: Role of intra-pore diffusion

We investigated the relative contributions of intra-pore diffusion (via membrane thickness) and partitioning into nanofiltration (NF) membrane pores (via membrane pore size and ion hydration energy) to the apparent energy barriers for ion transport in NF membranes. Using polyelectrolyte layer-by-layer assembly, we independently altered NF membrane thickness as well as membrane pore size and then determined the apparent energy barriers to bromide and fluoride transport through the fabricated membranes. Membrane thickness and pore size were estimated using an AFM scratch technique and the hydrodynamic pore transport model, respectively. By increasing the number of polyelectrolyte bilayers from four to ten, the polyelectrolyte film thickness increased from 28 to 77 nm, while the apparent energy barriers to bromide transport through the membranes with four, seven, and ten bilayers were negligibly affected (4.4, 3.4, and 3.9 kcal mol−1, respectively, at 1.7 bar). Instead, we found that solute flux and the apparent energy barriers to ion transport were significantly affected by both membrane pore size and ion hydration energy. Overall, our results support the traditional energy barrier-based models for ion transport in membranes and the recently proposed notion that ion dehydration at the solution-membrane interface is the rate-limiting step during transport through NF membranes.

Sonication-assisted Layer-by-Layer self-assembly nanoparticles for resveratrol delivery.

This paper advances the development of a novel drug nanodelivery solution to the oral administration of resveratrol (RSV), a low soluble drug whose recognized therapeutic applications are circumscribed when administered in the free compound form. Layer-by-Layer (LbL) self-assembly is an emergent nanotechnology proposed to address this concern with means to afford control over key formulation parameters, which are able to ultimately promote an improved pharmacokinetics. LbL self-assembly consists in the sequential adsorption of oppositely charged polyelectrolytes upon a low soluble drug nanoparticle (NP) template, giving rise to onion-like multilayered nanoarchitectures. In this work, RSV nanoprecipitation followed by LbL self-assembly of polyelectrolytes, led by a washless approach, was carried out by using the cationic poly(allylamine hydrochloride) (PAH) and the anionic dextran sulfate (DS) as polyelectrolytes towards the nanoencapsulation of RSV. Each saturated polyelectrolyte layer deposition involved the rigorous polyelectrolyte concentration assessment which was accomplished by tracing titration curves. This way, aqueous RSV nanocores and RSV LbL nanoformulations with a distinct number of PAH/DS bilayers were developed, including 2.5 (RSV-(PAH/DS)2.5 NPs), 5.5 (RSV-(PAH/DS)5.5 NPs) and 7.5 (RSV-(PAH/DS)7.5 NPs) bilayered nanoformulations. Homogenous particle size distributions at the desired nanoscale interval (ca. 116-220 nm; polydispersity index below 0.15), good colloidal (zeta potential magnitudes ca. ± 20-30 mV) and chemical stabilizations, high encapsulation efficiency (above 90%) together with an excellent cytocompatibility with Caco-2 cells (cell viability above 90%) were observed for all the nanoformulations. Eventfully, LbL NPs promoted a controlled release of RSV pursuant to the number of polyelectrolyte bilayers under simulated gastrointestinal conditions, particularly in the intestine medium, emphasizing their biopharmaceutical advantage. Our findings manifestly pinpoint that LbL PAH/DS NPs constitute a promising nanodelivery system for the oral delivery of RSV, providing a rational strategy to enlarge the implementation range of this interesting polyphenol, which is possibly the most actively investigated phytochemical worldwide.