Self-assembled Polyelectrolyte Research Articles

Nanofibrous polyelectrolyte complex incorporated BSA-alginate composite bioink for 3D bioprinting of bone mimicking constructs

Although several bioinks have been developed for 3D bioprinting applications, the lack of optimal printability, mechanical properties, and adequate cell response has limited their practical applicability. Therefore, this work reports the development of a composite bioink consisting of bovine serum albumin (BSA), alginate, and self-assembled nanofibrous polyelectrolyte complex aggregates of gelatin and chitosan (PEC-GC). The nanofibrous PEC-GC aggregates were prepared and incorporated into the bioink in varying concentrations (0 % to 3 %). The bioink samples were bioprinted and crosslinked post-printing by calcium chloride. The average nanofiber diameter of PEC-GC was 62 ± 15 nm. It was demonstrated that PEC-GC improves the printability and cellular adhesion of the developed bioink and modulates the swelling ratio, degradation rate, and mechanical properties of the fabricated scaffold. The in vitro results revealed that the bioink with 2 % PEC-GC had the best post-printing cell viability of the encapsulated MG63 osteosarcoma cells and well oragnized stress fibers, indicating enhanced cell adhesion. The cell viability was >90 %, as observed from the MTT assay. The composite bioink also showed osteogenic potential, as confirmed by the estimation of alkaline phosphatase activity and collagen synthesis assay. This study successfully fabricated a high-shape fidelity bioink with potential in bone tissue engineering.

Theoretical and experimental research of polyelectrolyte multilayer membrane prepared by layer by layer self-assembly

Layer-by-layer self-assembly of polyelectrolytes is one of the most promising methods for preparing nanofiltration membranes. Here poly (sodium 4-styrenesulfonate) (PSS) and poly (diallyldim-ethylammonium chloride) (PDADMAC) were chosen to prepare polyelectrolyte multilayer (PEM) membrane. The effects of background salt concentration, PSS concentration, background salt types, the number of layers and the outermost functional groups on the separation performance of the PEM were investigated systematically. Molecular dynamic simulation was employed to simulate the influence of background salt on the diffusion of PDADMAC. The simulation results agree well with the experimental results. The optimized (PSS/PDADMAC)4.5 membrane with Na2SO4 as background salt shows permeance of 15.9 LMH/bar, Na2SO4 rejection of 98.2 %, and an excellent stability. Our study provides both theoretical and experimental supports for the preparation of PEM membranes using LBL method.

Multivalent Salt-Induced Self-Assembly of Amphiphilic Polyelectrolytes of Different Charge Fractions: A Coarse-Grained Molecular Dynamics Simulation Study.

Amphiphilic polymers with both hydrophobic and hydrophilic blocks are of great interest for their potential applications in drug delivery. Their self-assembly behavior in response to environmental factors like ion charge and multivalent salt concentration has been the subject of recent investigation. Our study utilizes coarse-grained molecular dynamics simulations to investigate the aggregation behavior of amphiphilic copolymers upon introducing tetravalent salt at varying charge fractions. We identify a critical concentration, Cs*, where the aggregation number reaches its maximum for each charge fraction, followed by a subsequent decrease at the excessive salt regime. This study reveals distinct morphological transitions in response to increasing salt concentration and decreasing charged fractions, namely, (i) stable dispersed micelles, (ii) a singular micelle comprising all copolymer chains, and (iii) redispersed micelles, particularly evident at lower charged fractions. Our study highlights the significant influence of tetravalent salt and charge fractions of polyelectrolyte chains on the self-assembly behavior of polyelectrolyte copolymers.

Bioinspired Self-Assembly of Metalloporphyrins and Polyelectrolytes into Hierarchical Supramolecular Nanostructures for Enhanced Photocatalytic H2 Production in Water.

Polypeptides, as natural polyelectrolytes, are assembled into tailored proteins to integrate chromophores and catalytic sites for photosynthesis. Mimicking nature to create the water-soluble nanoassemblies from synthetic polyelectrolytes and photocatalytic molecular species for artificial photosynthesis is still rare. Here, we report the enhancement of the full-spectrum solar-light-driven H2 production within a supramolecular system built by the co-assembly of anionic metalloporphyrins with cationic polyelectrolytes in water. This supramolecular photocatalytic system achieves a H2 production rate of 793 and 685 μmol h-1 g-1 over 24 h with a combination of Mg or Zn porphyrin as photosensitizers and Cu porphyrin as a catalyst, which is more than 23 times higher than that of free molecular controls. With a photosensitizer to catalyst ratio of 10000 : 1, the highest H2 production rate of >51,700 μmol h-1 g-1 with a turnover number (TON) of >1,290 per molecular catalyst was achieved over 24 h irradiation. The hierarchical self-assembly not only enhances photostability through forming ordered stackings of the metalloporphyrins but also facilitates both energy and electron transfer from antenna molecules to catalysts, and therefore promotes the photocatalysis. This study provides structural and mechanistic insights into the self-assembly enhanced photostability and catalytic performance of supramolecular photocatalytic systems.

Activating Illite kaolinite clay with CTAB for adsorbing Methylene blue: Isotherms, Kinetics, and thermodynamics studies

In this study, a stable multilayered adduct of maghemite surfactant and clay was created by sandwich-like electrostatic self-assembly of cationic polyelectrolytes of cetyltrimethylammonium bromide (CTAB) with illite kaolinite (IKaol) clay. The adsorptive property of IKaol/CTAB towards MB from . Aquatic system uptake was investigated. Its characteristics were analysed using X-ray powder diffraction, Fourier transform-infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and the zero point of charge. To attain higher performance of the IKaol/CTAB for MB adsorption, the primary key factors that influence the MB dye, such as (A: loading CTAB into the composite matrix of IKaol), adsorbent dose (B: 0.02–0.06 g), pH (C: 4–10), temperature (D: 30–60 °C), and time (E: 5–60 min) , were optimised using the Box–Behnken design method. The obtained results show that the highest MB removal efficiency of 86.24 % was observed at the following significant interactions: AB, BC, and AC and at optimum adsorption operation parameters (A: 0%, B: 0.06 g, C: 7, D: 45◦C, and E: 17.5 min). At these optimum conditions, the best adsorption capacity of MB dye (114.94 mg/g) was recorded at 45°C. The most effective isotherms and kinetic models were the Freundlich and pseudo-second-order kinetic models. The MB dye adsorption mechanism by IKaol can be assigned to several interactions, such as electrostatic attractions, n-π interaction, and hydrogen bonding interactions. The results of this study demonstrate the viability of IKaol as a promising precursor for the creation of an efficient adsorbent that can be used to remove cationic dye from an aqueous environment.

Coordinated modulation of long non-coding RNA ASBEL and curcumin co-delivery through multicomponent nanocomplexes for synchronous triple-negative breast cancer theranostics

BackgroundAbnormally regulated long non-coding RNAs (lncRNAs) functions in cancer emphasize their potential to serve as potential targets for cancer therapeutic intervention. LncRNA ASBEL has been identified as oncogene and an anti-sense transcript of tumor-suppressor gene of BTG3 in triple-negative breast cancer (TNBC).ResultsHerein, multicomponent self-assembled polyelectrolyte nanocomplexes (CANPs) based on the polyelectrolytes of bioactive hyaluronic acid (HA) and chitosan hydrochloride (CS) were designed and prepared for the collaborative modulation of oncogenic lncRNA ASBEL with antago3, an oligonucleotide antagonist targeting lncRNA ASBEL and hydrophobic curcumin (Cur) co-delivery for synergetic TNBC therapy. Antago3 and Cur co-incorporated CANPs were achieved via a one-step assembling strategy with the cooperation of noncovalent electrostatic interactions, hydrogen-bonding, and hydrophobic interactions. Moreover, the multicomponent assembled CANPs were ulteriorly decorated with a near-infrared fluorescence (NIRF) Cy-5.5 dye (FCANPs) for synchronous NIRF imaging and therapy monitoring performance. Resultantly, MDA-MB-231 cells proliferation, migration, and invasion were efficiently inhibited, and the highest apoptosis ratio was induced by FCANPs with coordination patterns. At the molecular level, effective regulation of lncRNA ASBEL/BTG3 and synchronous regulation of Bcl-2 and c-Met pathways could be observed.ConclusionAs expected, systemic administration of FCANPs resulted in targeted and preferential accumulation of near-infrared fluorescence signal and Cur in the tumor tissue. More attractively, systemic FCANPs-mediated collaborative modulating lncRNA ASBEL/BTG3 and Cur co-delivery significantly suppressed the MDA-MB-231 xenograft tumor growth, inhibited metastasis and extended survival rate with negligible systemic toxicity. Our present study represented an effective approach to developing a promising theranostic platform for combating TNBC in a combined therapy pattern.

Development of a novel thermogelling PEC-based ECM mimicking nanocomposite bioink for bone tissue engineering

Non-union of large bone defects has been an existing clinical problem. 3D extrusion-based bioprinting provides an efficient approach to tackle such problems. This approach enables the use of various biomaterials, cell types and growth factors in developing a superior bone graft that is specific to the defect. In this article, we have designed and printed an ECM mimicking, self-assembled polyelectrolyte complex (PEC) based fibrous bioink using natural polymers like chitosan-polygalacturonic acid (PGA) and other biomaterials – gelatin, laponite and nanohydroxyapatite with a modified 3D printer. The developed bioink possesses a thermo-reversible sol-gel transition at physiological pH and temperature. Here, we demonstrated that post-printing, our fiber-reinforced bioink had significant cell proliferation with cell viability of >80% and negligible cell morbidity. The practicability of developing this self-assembled PEC-based bioink was assessed. Bioink with 4% gelatin (PECHLG4) had optimal printability with a minimal swelling ratio of approximately 3%. The printed scaffold had integrity for a period of 8 days under 0.5 mg/mL lysozyme concentration. We also evaluated the mechanical property of the bioink using compression analysis which gave an elastic modulus of 16 KPa. This combination of natural polymers and nanocomposite, along with a fibrous network of PECs, is itself a novel approach for 3D bioprinting and can be a preliminary proposition for the treatment of large bone defects.

Hybrid Polyelectrolyte Capsules Loaded with Gadolinium-Doped Cerium Oxide Nanoparticles as a Biocompatible MRI Agent for Theranostic Applications.

Layer-by-layer (LbL) self-assembled polyelectrolyte capsules have demonstrated their unique advantages and capability in drug delivery applications. These ordered micro/nanostructures are also promising candidates as imaging contrast agents for diagnostic and theranostic applications. Magnetic resonance imaging (MRI), one of the most powerful clinical imaging modalities, is moving forward to the molecular imaging field and requires advanced imaging probes. This paper reports on a new design of MRI-visible LbL capsules, loaded with redox-active gadolinium-doped cerium oxide nanoparticles (CeGdO2-x NPs). CeGdO2-x NPs possess an ultrasmall size, high colloidal stability, and pronounced antioxidant properties. A comprehensive analysis of LbL capsules by TEM, SEM, LCSM, and EDX techniques was carried out. The research demonstrated a high level of biocompatibility and cellular uptake efficiency of CeGdO2-x-loaded capsules by cancer (human osteosarcoma and adenocarcinoma) cells and normal (human mesenchymal stem) cells. The LbL-based delivery platform can also be used for other imaging modalities and theranostic applications.

Submicron polymer particles loaded with piperine: Preparation from fucoidan and evaluation of morphology, release profile, and antioxidant activity

A combination of two methods, polyelectrolyte self-assembly of fucoidan–chitosan and isocyanide-based multicomponent reactions, was used to obtain submicron polymer particles suitable for lyophilization. Piperine, an alkaloid and the major bioactive compound found in black pepper, is endowed with numerous biological activities; however, its application is hindered by low solubility and poor delivery. To overcome this problem, piperine was loaded into the submicron polymer particles obtained. These particles were subjected to lyophilization to assess their ability to redisperse in aqueous solution after drying and their stability. The characterization of the nanoparticles by dynamic light scattering revealed particle sizes of 219.67 ± 0.61 and 355.63 ± 14.49 nm for fucoidan–chitosan nanoparticles and piperine-loaded nanoparticles, respectively. Also, an irregular spherical piperine-loaded nanoparticle was found using atomic force microscopy. An encapsulation efficiency of 92.78% ± 0.02% was measured with UV/visible spectroscopy. In vitro, the release profile of piperine from the nanoparticles showed a significant release and faster dissolution rate than free piperine. For the release mechanism of piperine from the nanoparticle, the Korsmeyer–Peppas model was the best fit with a correlation coefficient (R2) close to 1. The antioxidant activity of the piperine-loaded nanoparticles was significantly higher than that of the unformulated piperine. The piperine-loaded nanoparticles also exhibited positive stability against stress from lyophilization. Therefore, fucoidan–chitosan nanoparticles to improve the bioavailability of piperine, as well as enhance antioxidant activity, and could be used as a nutraceutical.

Densification and polyelectrolyte assisted fabricating laminated wood composites for outstanding flame retardancy and mechanical properties

Laminated wood composites have widely used in construction, furniture and decoration; however, it remains a great challenge to address the trade-off between flame retardancy and mechanical strength in applications. In this work, we reported a strategy for fabricating a flame-retardancy-improved and mechanically strengthened laminated wood composites via delignification, densification and self-assembly of polyelectrolyte. The delignification significantly increased the porosity of wood cell walls, facilitating the impregnation and accumulation of an intermediate adhesion molecule of polyethyleneimine (PEI) within wood cell walls. It provided a sticky bridge to enhance crosslinking network with ammonium polyphosphate (APP) and wood cell walls in process of densification. Hence, a densely-laminated wood coordination with PEI/APP flame-retardant layer can enable excellent flame-retardant properties with an increase of 77.30% in limited oxygen index and a significant decrease of 24.22% in peak heat release rate (120 s) compared to control laminated wood composite. Meanwhile, the strains transferred more uniformly in the interior of wood composites across the stable crosslinking network via digital image correlation (DIC), resulting in an enhanced bonding strength. Besides, the permeation and distribution of PEI within wood cell walls can be successfully observed with the fluorescence imaging by chemical grafted the fluorescent molecule probe. This work offered a strategy for designing wood composite with high mechanical properties and flame-retardant for construction applications.

Perovskite Solar Cells with an SbX3 (X = Cl, I) Interface Dipole Layer

Forming an interface dipole moment pointing from the absorber to the oxide substrate can improve the open-circuit voltage (VOC) of perovskite solar cells (PSCs) without affecting photocurrent. In past studies, however, interface dipole layers were generally formed using organic self-assembled monolayers or polyelectrolytes, which raises concerns about intrinsic stability. Meanwhile, perovskites’ substrate-dependent electronic properties question the apparent correlation between the oxide’s work function and the built-in voltage. In this work, we propose an interface dipole layer based on solution-processable metal halides, which increases the built-in voltage of the n–i–p diode by simultaneously reducing the electron transport layer’s work function and strengthening the n-type characteristics of the perovskite absorber. The n–i–p-structured PSCs with the SbX3 dipole layer achieve substantially enhanced VOC (1.171 V) and power conversion efficiency (23.11%). Further experiments and calculations confirm that the proposed dipole model can explain the VOC enhancement qualitatively and quantitatively.

Interactions between Rigid Polyelectrolytes Mediated by Ordering and Orientation of Multivalent Nonspherical Ions in Salt Solutions.

Multivalent ions in solutions with polyelectrolytes (PEs) induce electrostatic correlations that can drastically change ion distributions around the PEs and their mutual interactions. Using coarse-grained molecular dynamics simulations, we show how in addition to valency, ion shape and concentration can be harnessed as tools to control rigid like-charged PE-PE interactions. We demonstrate a correlation between the orientational ordering of aspherical ions and how they mediate the effective PE-PE attraction induced by multivalency. The interaction type, strength, and range can thus be externally controlled in ionic solutions. Our results can be used as generic guidelines to tune the self-assembly of like-charged polyelectrolytes by variation of the characteristics of the ions.

Self-assembly of amphiphilic polyelectrolytes in trivalent salt solution.

Multivalent salt plays important roles in polyelectrolyte (PE) systems. Some special effects, such as ion mediated electrostatic correlation and reentrant condensation can be induced in the presence of multivalent salt. In this work, the self-assembly behaviors of diblock PEs in trivalent salt solutions are mainly investigated by molecular dynamics (MD) simulations, and partial results are qualitatively verified by experiments. The electrostatic correlation between PE chains and trivalent counterions is first enhanced with the increase of salt concentration, and then the large complexes of co-ions and trivalent counterions reduce the correlation at the excessive salt regime. Therefore, the electrostatic correlation mediated by trivalent ions shows a non-monotonic dependence on salt content. It should be noted that one-dimensional chain-like and two-dimensional planar network supra-micellar structures are obtained at different concentrations of PEs. It is the strong electrostatic correlation mediated by trivalent counterions that leads to the cross-linking of micelles, and homogeneous spherical micelles rather than anisotropic micelles are used as building blocks. Both of these supra-micellar structures predicted by simulations are qualitatively confirmed by experiments, and a micron sized long polymer chain and planar networks of inter-connected micelles are demonstrated in transmission electron microscopy (TEM) images. Reentrant behavior of the assembled micelles is demonstrated at a lower polymer concentration. The transitions from a dispersed micellar phase to a fully phase separated phase (where all the copolymer chains aggregate into one micelle to precipitate out of the solution) and to the re-dissolution of micelles are displayed with an increase in trivalent salt. The non-monotonic dependence of electrostatic correlation on the salt content is well displayed by the four states of the assembled micelles: (i) dispersed micelles, (ii) a single micelle comprising of all copolymer chains, (iii) micellar complex, and (iv) re-dispersed micelles. Our analysis may provide guidance for cross-linking of isotropic micelles into superstructures.

Polyelectrolyte complex scaffoldings for photocrosslinked hydrogels

Self-assembled polyelectrolyte complex-based scaffoldings to address the limitations and enrich the microstructure and the mechanical properties of photocrosslinked hydrogels.

Periodic Self-Assembly of Poly(ethyleneimine)-poly(4-styrenesulfonate) Complex Coacervate Membranes.

Coacervation is a self-assembly strategy based on the complexation of polyelectrolytes, which is utilized in biomedicine and agriculture, as well as automotive and textile industries. In this paper, we developed a new approach to the on-demand periodic formation of polyelectrolyte complexes through a Liesegang-type hierarchical organization. Adjustment of reaction conditions allows us to assemble materials with a tunable spatiotemporal geometry and establish materials' production cycles with a regulated periodicity. The proposed methodology allows the membrane to self-assemble when striving to reach balance and self-heal after exposure to external stimuli, such as potential difference and high pH. Using chronopotentiometry, K+ ion permeability behavior of the PEI-PSS coacervate membranes was demonstrated. The periodically self-assembled polyelectrolyte nanomembranes could further be integrated into novel energy storage devices and intelligent biocompatible membranes for bionics, soft nanorobotics, biosensing, and biocomputing.

Novel Anion-Exchange Blend Membranes Comprised of a Commercially Available & Water-Soluble Ionomer for All-Vanadium Redox Flow Batteries

The All-Vanadium Redox Flow Battery is a promising technology for solving the problem of cost-efficient and safe large-scale storage of renewable energies [1]. One key component of the batteries, which alters the performance and long-term stability of those systems, is the membrane. For this purpose, Nafion based membranes are often used. However, these membranes are high in cost and show a significant capacity fading and reduction of coulombic efficiency mainly due to crossover of vanadium species [2]. One way around this is to use commercially available, low-cost materials with positively charged ammonium groups, which can effectively repel positively charged vanadium species due to the Donnan exclusion effect [3, 4].In this work we present novel anion-exchange blend membranes comprised of a commercially available and water-soluble ionomer and a PBI blend matrix, which can be used in All-Vanadium Redox Flow batteries. For this approach the water-soluble ionomer was modified to achieve solubility in organic solvents and miscibility with the matrix polymer. The resulting membranes show good mechanical properties even at high IECs and can be modified in a wide range of properties by adjusting the amounts of ionomer and matrix polymer and/or by the addition of crosslinking agents.The above-mentioned membranes were characterised ex-situ by using EIS, NMR spectroscopy, IR spectroscopy, DMA, TGA, tensile tests and permeability tests. In addition, first promising in-situ characterisations were performed in a VRFB single-cell test station.Literature[1] Fan, X; Liu, B; Liu, J; Ding, J; Han, X; Deng, Y; Lv, X; Xie, Y; Chen, B; Hu, W; Zhong, C.: Battery Technologies for Grid-Level Large-Scale Electrical Energy Storage. Trans. Tianjin Univ. 2020, 92 – 103.[2] Düerkop, D; Widdecke, H; Schilde, C; Kunz, U; Schmiemann, A.: Polymer Membranes for All-Vanadium Redox Flow Batteries: A Review. Membranes 2021.[3] Xi, J; Wu, Z; Teng, X; Zhao, Y; Chen, L; Qiu, X.: Self-assembled polyelectrolyte multilayer modified Nafion membrane with suppressed vanadium ion crossover for vanadium redox flow batteries. J. Mater. Chem. 2008, 1232.[4] Mohammadi, T; Kazacos, M.: Modification of anion-exchange membranes for vanadium redox flow battery applications. Journal of Power Sources 1996, 179 – 186.

Molecular sieving through 'layer-by-layer' self-assembly of polyelectrolytes and highly crosslinked graphene oxide

Lack of access to potable water and abating levels of ground water level demands the reuse of unconventional water sources after remediating it in a sustainable way. In this context, purifying brackish, land and sea water seems a feasible solution to the ever-growing population.In this work, a novel composite membrane was fabricated by 'layer-by-layer' self-assembly of poly-dopamine (PDA) and polystyrene sulfonate (PSS) supported on a highly crosslinked graphene oxide (GO) membrane to sieve ions to purify contaminated water as well as enhance the resistance towards chlorine. This GO membrane was sandwiched between layers of various nanoporous polyvinylidene difluoride (PVDF) membranes obtained by selectively etching out the PMMA component from the demixed blends. The blend membranes were designed following the melt-extrusion process and subsequent quenching to facilitate confined crystallization of PVDF and selective etching of PMMA. The membranes with different pore sizes were tuned on varying the composition in blends and a gradient in microstructure was achieved by stitching the membranes. Pure water flux, salt rejection, dye removal, and antibacterial activity were performed to study the membrane's efficiency. The GO membrane was chemically crosslinked with methylenediamine to impart dimensional stability and to enhance rejection efficiency through the nanoslits that GO offers. Besides effective rejection, the sandwiched membrane was modified with ‘layer-by-layer’ self-assembly of polyelectrolytes on the surface to improve the chlorine tolerance performance. This strategy resulted in an excellent salt (about 95% and 97% for monovalent and divalent ion, respectively) and dye rejection (100% for both cationic and anionic dye), besides facilitating excellent chlorine tolerance performance. Moreover, this modified membrane showed superior antifouling properties (flux recovery ratio is more than 90%) and excellent antibacterial performance (near about 3 log reduction).Thus the concept of using layer-by-layer self-assembly of polycations (PDA) and polyanions (PSS) onto a hierarchical chemically modified GO sandwiched PVDF membrane proved to be a productive strategy to purify contaminated water. Thus the membrane can be a potential candidate for domestic as well as industrial application.

Self-assembled polyelectrolyte complexes of chitosan and fucoidan for sustained growth factor release from PRP enhance proliferation and collagen deposition in diabetic mice.

Diabetic wound management is a serious health care challenge due to higher rates of relapse, expensive treatment approaches, and poor healing outcomes. Among cell-based therapies, use of platelet-rich plasma (PRP) has been shown to be effective for diabetic wounds, but its poor shelf-life limits its clinical use. Here, we demonstrate a simple but effective polymer system to increase the shelf-life of PRP by developing a polyelectrolyte complex with dropwise addition of chitosan solution containing PRP by simple mixing at room temperature. Thus, prepared chitosan-fucoidan (CF) carrier complex encapsulated more than 95% of the loaded PRP. The resulting CF/PRP colloids were spherical in shape and ensured extended PRP release up to 72h at 37°C. Routine characterization (FT-IR, XRD, SEM) showed the material properties. The biological assays showed that CF complexes were biocompatible while CF/PRP enhanced the proliferation of fibroblasts and keratinocytes via higher Ki67expression and fibroblast migration. Further investigations using a diabetic mouse model demonstrated significantly higher wound contraction and histopathological observations showed increased fibroblast migration, and collagen and cytokeratin deposition in treatment groups. The results are suggestive of the efficacy of CF/PRP as a cost-effective topical formulation for the sustained delivery of growth factors in treating chronic diabetic wounds.

Fluorescence Signal Enhancement by a Spray-Assisted Layer-by-Layer Technique on Aluminum Tape Devices for Biosensing Applications

Layer-by-layer (LbL) self-assembled polyelectrolyte multilayer (PEM) films are a simple yet elegant bottom-up technology to create films at the nano-microscale. This low-cost technology has been widely used as a universal functionalization technique on a broad spectrum of substrates. Biomolecules under investigation can be incubated onto films based on complementary charge interactions between the films and biomolecules. There is a great demand for developing an ultralow-cost biosensing device, which can optimally enhance the fluorescence signal of the adsorbed biomolecules from the traditional labeled sensing platforms. In this work, we have incorporated a blend of the conventional metal enhanced fluorescence technology and the PEM as a dielectric spacer and functionalized film, coated on an aluminum paper (tape)-based substrate. These device has been found to be capable of holding biomolecules in three-dimensional PEM space. The devices fabricated by the proposed spray LbL technique provide significant fluorescence signal enhancement by holding a relatively higher mass per volume of the adsorbed biomolecules, when compared to traditional spin- and dip-coating techniques. Interestingly, our proposed device has expressed a fluorescence enhancement factor, which is 9 times higher than PEM-functionalized glass-based devices. To demonstrate the practical utility of our devices, we also compared our devices to Whatman FAST slides. Our experimental fluorescence results are almost comparable to Whatman FAST slides. Such PEM devices fabricated on top of low-cost aluminum tape using a spray LbL technique give new insights into the future development of ultralow-cost, high-throughput, and disposable lab-on-chip diagnostic applications.

Ionic strength directed self-assembled polyelectrolyte single-bilayer membrane for low-pressure nanofiltration

Ionic strength directed self-assembled polyelectrolyte single-bilayer membrane for low-pressure nanofiltration