Langmuir-Blodgett Technique Research Articles

Filling the gaps: Introducing plasticizers into π-conjugated OPE-NH2 Langmuir layers for defect-free anisotropic interfaces and membranes towards unidirectional mass, charge, or energy transfer

The construction of ultrathin membranes from linearly aligned π-electron systems is advantageous for targeted energy, charge, or mass transfer. The Langmuir-Blodgett (LB) technique enables the creation of such membranes, especially with amphiphilic π-electron systems. However, these systems often aggregate, forming rigid Langmuir monolayers with defects or holes. In this study we introduce plasticizers to effectively address this issue. To create anisotropic membranes, we used an oligo(phenylene ethynylene) derivative (OPE-NH2) as an linear amphiphile and bisphenol A di-tert-butyl ester (BPAE) as a plasticizer. We analyzed surface pressure (mean molecular area) (Π(mma)) isotherms and characterized Langmuir monolayers with Brewster Angle Microscopy (BAM), to determine the optimal miscibility of OPE-NH2 with BPAE. Detailed analysis of hole areas filled was performed through image binarization. We identified an optimal BPAE concentration of 4 mol-% in the OPE-NH2 Langmuir monolayer. Our BAM image evaluation via binarization determined the difference between the mean molecular areas of close-packed Langmuir domains and those quantified via the Π(mma) isotherm. This study presents an automated method for BAM image analysis and a new approach for fabricating defect-free anisotropic molecular monolayers of π-conjugated amphiphiles.

Strontium-containing mineralized phospholipid coatings improve osseointegration in osteoporotic rats.

Surface treatments play an important role in enhancing the osseointegration of Titanium (Ti) and its alloys. This study introduces a method employing biomimetic hydroxyapatite (Hap) deposition guided by molecularly organized phospholipids, affixed to the metal implant surface. Using the Langmuir-Blodgett technique, phospholipids were deposited onto Ti-screws by using CaCl2 or CaCl2/SrCl2 aqueous solution in the subphase of a Langmuir trough in the target proportion (i.e. 10 and 90 mol% of Sr2+ in relation of Ca2+) followed by immersion in phosphate buffer and in supersaturated simulated body fluid. Coating composition and morphology were evaluated using infrared spectroscopy and scanning electron microscopy, respectively, while contact angle measurements assessed coating wettability and surface energy. Randomized screws were then implanted into the tibias of healthy and osteoporotic female rats (G1: Control-Machined, G2: Hap, G3: HapSr10, G4: HapSr90). Osseointegration, assessed 60 days post-implantation, included reverse torque, fluorochrome area, bone tissue-screw contact area, and linear extent of bone-screw contact. Results, grouped by surface treatment (Machined, Hap, HapSr10, HapSr90), revealed that the deposition of Hap, HapSr10, and HapSr90 resulted in thin and rough coatings composed of hydroxyapatite (Hap) on the screw surface with nanoscale pores. The coatings resulted in increased wettability and surface energy of Ti surfaces. The minerals are chemically similar to natural bone apatite as revealed by FTIR analysis. In vivo analyses indicated higher torque values for strontium-containing surfaces in the osteoporotic group (p = 0.02) and, in the control group superior torque for screw removal on the Hap surface (p = 0.023). Hydroxyapatite-treated surfaces enhance morphology, composition, and reactivity, promoting screw osseointegration in healthy and osteoporotic female rats. The incorporation of strontium into the mineral phase has been proposed to not only stimulate osteoblast activity but also reduce osteoclastic resorption, which may explain the improved outcomes observed here in experimental osteoporotic conditions.

Trace element selenium–augmented Kirschner wire with enhanced osteogenetic and antibacterial properties

The Kirschner wire (K-wire) is widely used in orthopedic external fixation due to its versatility and clinical effectiveness. However, a significant challenge associated with its use is the potential for bacterial migration, subsequent infection, and dislodgement as the wire penetrates the skin and bone. This study introduces a novel bioactive material, selenium/calcium silicate (Se/β-CS), achieved by integrating selenium—an essential trace element in the human body—into bioceramic calcium silicate. This integration was accomplished using a combined chemical co-deposition method and redox reaction. Furthermore, a uniform and controllable Se/β-CS coating was applied to the K-wire's surface using the Langmuir-Blodgett technique. This coating gradually releases active components—Si, Ca, and Se—that effectively eliminate bacterial infections and promote osteointegration. The findings of this study offer promising opportunities for the use of robust and multifunctional coating materials on implantable devices, particularly within the fields of orthopedics, transplantation, and surgery.

Fabrication and Self-Assembly Behavior of BPEF and BBPEF Composite Langmuir-Blodgett Films with Photovoltaic Conversion Properties.

The LB films prepared through the Langmuir-Blodgett (LB) technique are of significant importance for the fabrication of functional films such as optoelectronic materials and sensors. In this study, 9,9-bis (4-(2-hydroxy-ethoxy) phenyl) fluorene (BPEF) and 9,9-bis [3-phenyl-4-(β-hydroxy-ethoxy) phenyl] fluorene (BBPEF) were combined with saffron T (ST), methylene blue (MB) and Rhodamine B (RhB) dyes by LB technique to prepare ordered composite films. The nanostructures and morphologies of the composite films were analyzed by transmission electron microscopy (TEM) and atomic force microscopy (AFM). It was found that the films exhibited distinct aggregation morphologies. The UV-VIS absorption spectra showed that the concentration of dye molecules had a significant effect on the spectral characteristics. The contact Angle test shows that the prepared composite films are hydrophobic. The photovoltaic conversion performance of LB composite films was studied by transient photocurrent response experiments. It was found that BPEF/dye and BBPEF/dye composite films exhibited significant responses in photocurrent. In particular, BPEF/RhB and BBPEF/RhB composite films demonstrated excellent photoresponsive performance. This study used LB technology in combination with BPEF and BBPEF to demonstrate enhanced photocurrent and stable performance of LB film, which provided ideas for expanding the application range of materials.

Flexible electrospun test strips functionalized with a graphene oxide/doxorubicin complex for dopamine detection

A novel flexible test strip has been developed for the selective and sensitive detection of dopamine (DA) using an electrospun polyacrylonitrile nanofiber membrane as a substrate and doxorubicin (DOX)-functionalized graphene oxide (GO) as a fluorescent ligand. Employing the Langmuir-Blodgett technique, the fluorescent probe of GO/DOX was controllably and flatly applied onto the surface of nanofiber membranes. The adsorption behavior of DA and DOX on GO in solution and on the surface of solid test strips has been investigated, respectively. The results showed that DA exhibited a higher affinity for GO, both in solution and on the surface of test strips, compared to DOX. Due to the competitive adsorption of DOX and DA onto GO, the addition of DA to the GO/DOX complex led to a significant fluorescence enhancement, attributed to the replacement of the GO-supported DOX with DA of a higher adsorption affinity to GO, enabling the detection of DA. This nanofiber-based method proves to be simple, sensitive, selective, and effectively minimizes interference from common biomolecules and small molecules in serum. Thus, this portable, cost-effective, and selective nanofiber strip holds great promise for early diagnosis of neurodegenerative diseases by measuring DA levels.

Large-Scale Formation of a Close-Packed Monolayer of Spheres Using Different Colloidal Lithography Techniques.

The possibility of using colloidal lithography at the industrial level depends on the ability to form defect-free coatings over large areas. The spin-coating method has not yet shown acceptable results, but a more detailed studying of the regularities of this process may improve the quality of masks. The Langmuir-Blodgett method is expected to be the most preferable for forming high-quality large-scale monolayers. Real-time controlling the surface pressure of the monolayer can allow to obtain close-packed arrays with long-range order. In this work, to develop the spin-coating technology, the influence of technological parameters (spin-coating speed and time, concentrations of components in suspension) on the substrate coverage area with a monolayer of polystyrene spheres (1.25 μm) was studied. An original automated Langmuir-Blodgett system was developed to study the influence of the monolayer surface pressure on its quality using polystyrene spheres (1.25, 1.8, 2.1 μm). The developed spin-coating technology resulted in a record coverage area (90%) of Si substrate (76 mm) and a defect-free hexagonally ordered domain area of 500 μm2. As a result of the developed Langmuir-Blodgett technique, a close-packed monolayer coating was obtained over the entire substrate area (coverage area 99.5%, defect-free domain area 3000 μm2) without the use of any surfactants.

Green and solid state reduction of GO monolayers sandwiched between Arachidic acid LB layers

A novel, single step and environment friendly solid state approach for reduction of graphene oxide (GO) monolayers has been demonstrated, in which, arachidic acid/GO/arachidic acid (AA/GO/AA) sandwich structure obtained by Langmuir-Blodgett (LB) technique was heat treated at moderate temperatures to obtain RGO sheets. Heat treatment of AA/GO/AA sandwich structure at 200 °C results in substantial reduction of GO, with concurrent removal of AA molecules. Such developed RGO sheets possess sp2-C content of ∼69 %, O/C ratio of ∼0.17 and significantly reduced I(D)/I(G) ratio of ∼1.1. Ultraviolet photoelectron spectroscopy (UPS) studies on RGO sheets evidenced significant increase in density of states in immediate vicinity of Fermi level and decrease in work function after reduction. Bottom gated field effect transistors fabricated with isolated RGO sheets displayed charge neutrality point at a positive gate voltage, indicating p-type nature, consistent with UPS and electrostatic force microscopy (EFM) measurement results. The RGO sheets obtained by heat treatment of AA/GO/AA sandwich structure exhibited conductivity in the range of 2–7 S/cm and field effect mobility of 0.03–2 cm2/Vs, which are comparable with values reported for RGO sheets obtained by various chemical/thermal reduction procedures. The extent of GO reduction is determined primarily by proximity of AA molecules and found to be unaltered with either escalation of heat treatment temperature or increase of AA content in sandwich structure. The single-step GO reduction approach demonstrated in this work is an effective way for development of RGO monolayers with high structural quality towards graphene-based electronic device applications.

Graphene Oxide Surface Modification of Reverse Osmosis (RO) Membrane via Langmuir-Blodgett Technique: Balancing Performance and Antifouling Properties.

The reverse osmosis water treatment process is prone to fouling issues, prompting the exploration of various membrane modification techniques to address this challenge. The primary objective of this study was to develop a precise method for modifying the surface of reverse osmosis membranes to enhance their antifouling properties. The Langmuir-Blodgett technique was employed to transfer aminated graphene oxide films assembled at the air-liquid interface, under specific surface pressure conditions, to the polyamide surface with pre-activated carboxylic groups. The microstructure and distribution of graphene oxide along the modified membrane were characterized using SEM, AFM, and Raman mapping techniques. Modification carried out at the optimal surface pressure value improved the membrane hydrophilicity and reduced the surface roughness, thereby enhancing the antifouling properties against colloidal fouling. The flux recovery ratio after modification increased from 65% to 87%, maintaining high permeability. The modified membranes exhibited superior performance compared to the unmodified membranes during long-term fouling tests. This membrane modification technique can be easily scaled using the roll-to-roll approach and requires minimal consumption of the modifier used.

Preparation of Langmuir-Blodgett composite films based on Bisphenol fluorene and Epoxy bisphenol fluorene with photovoltaic properties

The Langmuir-Blodgett (LB) technique can be used to obtain highly ordered arrangement and assembly of high polymer molecular chains, and the obtained LB films exhibit the controllable structures and special physicochemical properties. Here, we successfully prepared the composite LB films based on bisphenol fluorene (BPF) and epoxy bisphenol fluorene (DGPF) by LB technique, as well as explored the microstructures of the composite LB films by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The different aggregation states of various dye molecules in the composite LB films are investigated by UV–vis. Interestingly, the composite LB film electrodes exhibit promising photoelectrochemical properties. In particular, BPF/MB and DGPF/MB LB films show better photoelectric conversion efficiency. It is attributed to the ordered arrangement of BPF and DGPF and their effective aggregation with dye molecules, which improves the light absorption ability and charge transfer efficiency of the materials. Therefore, the prepared LB films based on the synthetic polymers BPF and DGPF are expected to play an important role in microelectronics.

Designing Microneedle Patch for Prophylaxis of Postoperative Atrial Fibrillation.

Postoperative atrial fibrillation (POAF) is a common complication following cardiac surgery, which often occurs within 30 postoperative days, especially peaking at 2-3 days. Antiarrhythmic medications such as amiodarone are recommended in clinical practice for the prophylaxis and treatment of POAF. However, conventional oral administration is hindered due to delayed drug action and high risks of systemic toxicity, and emerging localized delivery strategies suffer from a limited release duration (less than 30 days). Herein, we develop a microneedle (MN) patch for localized delivery of amiodarone to the atria in a "First Rapid and Then Sustained" dual-release mode. Specifically, this patch is composed of a needle array integrated with an amiodarone-loaded reservoir for a sustained and steady release for over 30 days; and an amiodarone-containing coating film deposited on the needle surface via the Langmuir-Blodgett technique for a rapid release at the first day. Upon this design, only one MN patch enables a higher drug accumulation in the atrial tissue at the first day than oral administration and simultaneously remains therapeutical levels for over 30 days, despite at a significantly reduced drug dosage (5.08 mg in total versus ∼10 mg per day), thereby achieving ideal preventive effects and safety in a rat model. Our findings indicate that this MN device provides a robust and efficient delivery platform for long-term prophylaxis of POAF.

Langmuir-Blodgett Transfer of Nanocrystal Monolayers: Layer Compaction, Layer Compression, and Lattice Stretching of the Transferred Layer.

Grazing incidence small angle X-ray scattering (GISAXS) was used to study the structure and interparticle spacing of monolayers of organic ligand-stabilized iron oxide nanocrystals floating at the air-water interface on a Langmuir trough, and after transfer to a solid support via the Langmuir-Blodgett technique. GISAXS measurements of the nanocrystal arrangement at the air-water interface showed that lateral compression decreased the interparticle spacing of continuous films. GISAXS also revealed that Langmuir-Blodgett transfer of the nanocrystal layers to a silicon substrate led to a stretching of the film, with a significant increase in interparticle spacing.

Preparation of Langmuir-Blodgett Films from Quinoxalines Exhibiting Aggregation-Induced Emission and Their Acidochromism.

The development of aggregation-induced emission (AIE)-exhibiting compounds heavily relies on our evolving comprehension of their behavior at interfaces, an understanding that still remains notably limited. In this study, we explored the preparation of two-dimensional (2D) sensing films from 2,3-diphenylquinoxaline-based diazapolyoxa- and polyazamacrocycles displaying AIE via the Langmuir-Blodgett (LB) technique. This systematic investigation highlights the key role of the heteroatom-containing tether of 2,3-diphenylquinoxalines in the successful fabrication of Langmuir layers at the air-water interface and the transfer of AIE-emitting supramolecular aggregates onto solid supports. Using both diazapolyoxa- and polyazamacrocycles, we prepared AIE-exhibiting monolayer films containing emissive supramolecular aggregates on silica, mica, and quartz glass and characterized them using ultraviolet-visible (UV-vis) and photoluminescence (PL) spectroscopies, atomic force microscopy (AFM) imaging, and fluorescence microscopy. We also obtained multilayer AIE-emitting films through the LB technique, albeit with increased complexity. Remarkably, by employing the smallest macrocycle N2C3Q, we successfully prepared LB films suitable for the visual detection of acidic vapors. This sensing material, which contains a much lesser amount of organic dye compared with traditional drop-cast films, can be regenerated and utilized for real-life sample analysis, such as monitoring the presence of ammonia in the air and the freshness of meat.

PH effect in Langmuir–Blodgett self-assembly of MoS2 and WS2 thin films

We reported Langmuir–Blodgett films of molybdenum disulphide and tungsten disulfide and studied the formation of MoS2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{Mo}}{\ ext{S}}_{2}$$\\end{document} and WS2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{WS}}_{2}$$\\end{document} layers. The effect of the subphase pH is investigated. Also, the influence of the subphase conditions on the number of layers was reported. By varying the pH of the buffer solution subphase, the solvent-to-nanoparticle interaction is changed and the compression of the layer during deposition is influenced. The stacking of the MoS2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{Mo}}{\ ext{S}}_{2}$$\\end{document} and WS2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{WS}}_{2}$$\\end{document} crystalline structure under the influence of subphase pH and the material concentration were investigated. Langmuir layers assembly is a useful method to manipulate the distribution of WS2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{WS}}_{2}$$\\end{document} and MoS2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{Mo}}{\ ext{S}}_{2}$$\\end{document}. Successful deposition of dichalcogenides at the air–water interface on silicon substrate was performed using Balance Langmuir–Blodgett technique. The characterization of WS2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{WS}}_{2}$$\\end{document} and films MoS2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{Mo}}{\ ext{S}}_{2}$$\\end{document} with X-ray diffraction, Raman spectroscopy, atomic force microscopy and scanning electron microscopy was carried out.

Detailed Study on the Interfacial Interaction between Different Polyoxometalates and Tetronic Block Copolymers Exploring the Langmuir-Blodgett Technique.

Polyoxometalates (POMs) interact with various biologically relevant entities. A basic understanding of this interaction is very important for various applications in the biological field. In this work, the focus is on the study of the interaction between tetronics and Keggin POMs. T701 and T90R4 are the two tetronics considered here; they have different solubilities in water due to different PPO/PEO ratios. The arrangement of PPO and PEO is also different with respect to the central ethylenediamine groups. Three different Keggin-type POMs, phosphomolybdic acid (PMA), phosphotungstic acid (PTA), and silicotungstic acid (STA), with different charge densities are chosen for an elaborate investigation using Langmuir-Blodgett technique. The observation is analyzed thoroughly, which shows both electrostatic interaction and adsorption of POMs on the PPO blocks of the tetronics due to the chaotropic effect, which is responsible for the binding of POMs (in subphase) with the tetronic monolayer. This interaction results in an expanded yet rigid monolayer for POM-tetronic association on the surface. Surface pressure vs mean molecular area isotherm is the key characterization to reach the conclusion. UV-vis spectroscopy, NMR, ITC, ellipsometric studies, FTIR, and SEM also serve as supportive characterization techniques.

Equipment-Free Fabrication of Thiolated Reduced Graphene Oxide Langmuir-Blodgett Films: A Novel Approach for Versatile Surface Engineering.

This research presents a novel method for the fabrication of mercapto reduced graphene oxide (m-RGO) Langmuir-Blodgett (LB) films without the need for specialized equipment. The conventional LB technique offers precise control over the deposition of thin films onto solid substrates, but its reliance on sophisticated instrumentation limits its accessibility. In this study, we demonstrate a simplified approach that circumvents the necessity for such equipment, thereby democratizing the production of m-RGO LB films. Thiolation of reduced graphene oxide (rGO) imparts enhanced stability and functionality to the resulting films, rendering them suitable for a wide range of applications in surface engineering, sensing, and catalysis. The fabricated m-RGO LB films exhibit favorable morphological, structural, and surface properties, as characterized by various analytical techniques including scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). Furthermore, the performance of the m-RGO LB films is evaluated in terms of their surface wettability, electrochemical behavior, and chemical reactivity. The equipment-free fabrication approach presented herein offers a cost-effective and scalable route for the production of functionalized graphene-based thin films, thus broadening the scope for their utilization in diverse technological applications.

Continuous protein-density gradients: A new approach to correlate physical cues with cell response.

To assess cellular behavior within heterogeneous tissues, such as bone, skin, and nerves, scaffolds with biophysical gradients are required to adequately replicate the in vivo interaction between cells and their native microenvironment. In this study, we introduce a strategy for depositing ultrathin films comprised of laminin-111 with precisely controlled biophysical gradients onto planar substrates using the Langmuir-Blodgett (LB) technique. The gradient is created by controlled desynchronization of the barrier compression and substrate withdrawal speed during the LB deposition process. Characterization of the films was performed using techniques such as atomic force microscopy and confocal fluorescence microscopy, enabling the comprehensive analysis of biophysical parameters along the gradient direction. Furthermore, human adipose-derived stem cells were seeded onto the gradient films to investigate the influence of protein density on cell attachment, showing that the distribution of the cells can be modulated by the arrangement of the laminin at the air-water interface. The presented approach not only allowed us to gain insights into the intricate interplay between biophysical cues and cell behavior within complex tissue environments, but it is also suited as a screening approach to determine optimal protein concentrations to achieve a target cellular output.

Interfacing Langmuir-Blodgett and Pickering Emulsions for the Synthesis of 2D Nanostructured Films: Applications in Copper Ion Adsorption.

This research focuses on developing a 2D thin film comprising a monolayer of silica nanoparticles functionalized with polyethyleneimine (PEI), achieved through a novel integration of Langmuir-Blodgett (L-B) and Pickering emulsion techniques. The primary aim was to create a nanostructured film that exhibits dual functionality: iridescence and efficient metal ion adsorption, specifically Cu(II) ions. The methodology combined L-B and Pickering emulsion polymerization to assemble and stabilize a nanoparticle monolayer at an oil/water interface, which was then polymerized under UV radiation to form an asymmetrically structured film. The results demonstrate that the film possesses a high adsorption efficiency for Cu(II) ions, with the enhanced mechanical durability provided by a reinforcing layer of polyvinyl alcohol/glycerol. The advantage of combining L-B and Pickering emulsion technology is the ability to generate 2D films from functional nanoparticle monolayers that are sufficiently sturdy to be deployed in applications. The 2D film's practical applications in environmental remediation were confirmed through its ability to adsorb and recover Cu(II) ions from aqueous solutions effectively. We thus demonstrate the film's potential as a versatile tool in water treatment applications owing to its combined photonic and adsorptive properties. This work paves the way for future research on the use of nanoengineered films in environmental and possibly photonic applications focusing on enhancing the film's structural robustness and exploring its broader applicability to other pollutants and metal ions.

The effect of nanobubbles on Langmuir-Blodgett films

Nanobubbles (NBs) are classified in two distinct categories: surface and bulk. Surface NBs are readily observed using atomic force microscopy (AFM), while the existence of bulk NBs has been a subject of debate, conflicting with the diffusion theory's predictions. Current methodologies for identifying bulk NBs yield inconclusive results. In this study, Langmuir Blodgett (LB) technique and AFM, are utilized to visualize NB imprints on anionic, cationic and zwitterionic lipid films deposited on glass-slide substrates. Our analysis of Langmuir monolayers compression isotherms reveals the impact of bulk NBs on lipid monolayer development. AFM scans of the deposited lipid films consistently show NB imprints. Notably, cationic and zwitterionic film depositions exhibit NB formations from the 1st layer, whereas in anionic films, these formations are observed only after the 3rd layer. These results suggest that the origin of these imprinted formations may be attributed to bulk NBs.

Plasmonic Properties of Self-Assembled Gold Nanocrescents: Implications for Chemical Sensing.

A bottom-up approach, the Langmuir-Blodgett technique, is used for the preparation of composite thin films of gold nanoparticles and polymers: poly(styrene-b-2-vinylpyridine), poly-2-vinylpyridine, and polystyrene. The self-assembly of poly(styrene-b-2-vinylpyridine) at the air-water interface leads to the formation of surface micelles, which serve as a template for the organization of gold nanoparticles into ring assemblies. By using poly-2-vinylpyridine in conjunction with low surface pressure, the distance between nanostructures can be increased, allowing for optical characterization of single nanostructures. Once deposited on a solid substrate, the preorganized gold nanoparticles are subjected to further growth by the reduction of additional gold, leading to a variety of nanostructures which can be divided into two categories: nanocrescents and circular arrays of nanoparticles. The optical properties of individual structures are investigated by optical dark-field spectroscopy and numerical calculations. The plasmonic behavior of the nanostructures is elucidated through the correlation of optical properties with structural features and the identification of dominant plasmon modes. Being based on a self-assembly approach, the reported method allows for the formation of interesting plasmonic materials under ambient conditions, at a relatively large scale, and at low cost. These attributes, in addition to the resonances located in the near-infrared region of the spectrum, make nanocrescents candidates for biological and chemical sensing.

Smart Energy Storage: W18O49 NW/Ti3C2Tx Composite-Enabled All Solid State Flexible Electrochromic Supercapacitors.

Developing a highly efficient electrochromic energy storage device with sufficient color fluctuation and significant electrochemical performance is highly desirable for practical energy-saving applications. Here, to achieve a highly stable material with a large electrochemical storage capacity, a W18O49 NW/Ti3C2Tx composite has been fabricated and deposited on a pre-assembled Ag and W18O49 NW conductive network by Langmuir-Blodgett technique. The resulting hybrid electrode composed of 15 layers of W18O49 NW/Ti3C2Tx composite exhibits an areal capacitance of 125mFcm-2, with a fast and reversible switching response. An optical modulation of 98.2% can be maintained at a current density of 5mAcm-2. Using this electrode, a bifunctional symmetric electrochromic supercapacitor device having an energy density of 10.26µWhcm-2 and a power density of 0.605mWcm-2 is fabricated, with high capacity retention and full columbic efficiency over 4000 charge-discharge cycles. Meanwhile, the device displays remarkable electrochromic characteristics, including fast switching time (5s for coloring and 7s for bleaching), and a significant coloration efficiency of 116cm2C-1 with good optical modulation stability. In addition, the device exhibits significant mechanical flexibility and fast switching while being stable over 100 bending cycles, which is promising for real-world applications.