Polymer Deposition Research Articles

Multidimensional analysis of textiles coated with electroactive polymers for actuators

This paper presents a multidimensional analysis of textiles coated with conductive polymers for actuators. The purpose of using multidimensional scaling analysis is to compare similarities and dissimilarities between conductive textiles obtained through conductive polymeric film deposition to observe the optimal value for electrical resistance and to select an adequate method to achieve conductive fabric using different polymers (polyethylene glycol, polyvinyl alcohol or polyvinylidene fluoride) and metal microparticles (copper or nickel). The multidimensional analysis is based on mapping a series of material properties from a proximity matrix (similarities or dissimilarities) between these properties. Multidimensional scaling allows rebuilding the exact map of the values (within approximately a symmetry or rotation). To fit dissimilarity or similarity matrices for multiple variables into one common space estimating the weight parameters for each variable, the INDSCAL model (individual differences multidimensional scaling) was used.

Additive manufacturing of polyamide 12 bulk structures using directed energy deposition with a thulium laser: Effect of process conditions on morphology and mechanical performance

Laser-based directed energy deposition of polymers (DED-LB/P) is a highly flexible additive manufacturing process capable of fabricating three-dimensional structures with a high degree of customization on free-form surfaces. In this article, the manufacturability of polyamide 12 bulk structures using DED-LB/P in combination with a thulium laser operating at a wavelength of 1.94 μm is investigated for the first time. The typical absorption bands at this wavelength eliminate the need for additives such as carbon-based nanoparticles, which would limit the range of applications. The generated structures were analyzed regarding porosity, thermal behavior, and mechanical properties to evaluate the potential of DED-LB/P with a thulium laser. As a consequence of the evaporation of absorbed moisture or ethanol residues resulting from powder preparation, a thermal pretreatment of the polymer powder reduced the porosity of the DED-LB/P structures to 0.9%. Depending on the processing parameters, the crystallinity of the produced structures ranged from 25.6% to 29.9%. For the tensile tests, the required geometries were milled from the DED-LB/P bulk structures. The results show that an ultimate tensile strength of up to 52 MPa, an elongation at break of up to 58%, and Young's modulus of up to 1590 MPa can be achieved. These remarkable mechanical properties are primarily attributed to the complete melting of the powder particles in DED-LB/P and the improved surface quality resulting from the milling process.

Metal–Polymer Joining by Additive Manufacturing: Effect of Printing Parameters and Interlocking Design

Additive manufacturing has a strong potential to produce sound metal–polymer joints using controlled polymer deposition on a metallic substrate. In this way, this study aimed to explore the morphological and mechanical properties of metal–polymer joints produced through material-extrusion-based AM using a pin-based macro-mechanical interlocking mechanism. Joints were fabricated with polylactic acid deposited onto a heated aluminium alloy substrate to form the connection. The optimisation process was focused on improving the printing parameters and pin geometries to reduce voids and enhance joint integrity. The results indicate that optimised samples exhibit superior mechanical resistance, achieving a maximum load improvement with an overall strength increase of 368.97% compared to non-optimised joints. A combined pin geometry (50% cylindrical, 50% conical) was found to be the most effective. Morphological analysis confirmed uniform polymer deposition, ensuring reliable joint performance. These findings underscore the critical role of geometric optimisation in enhancing the strength and durability of metal–polymer joints in AM applications.

Finite Element Analysis of Leaf Spring Fabricated Via Fused Deposition Modeling (FDM)

An introduction to fused deposition modeling, or 3D printing technology, will be given in this chapter. The basic idea of additive manufacturing and its underlying scientific theory will be presented at the outset of this chapter as a novel and emerging industrial technology. The parameters used to predict the melt deposition of polymers and their basic interactions with the structural component qualities will also be covered in this chapter. The chapter will provide a brief description of the quality features of FDM products concerning the process parameters. The additive manufacturing process will involve layering material to produce three-dimensional (3D) parts using a class of manufacturing technologies known as additive manufacturing (AM). This substance will include composite, metal, polymer, or concrete materials. A manufacturing process will need to have the following three main elements to be designated as an AM technique: making visual 3D models with computers and computer-aided design (CAD), utilizing a variety of CAD tools such as AutoCAD, SolidWorks, CATIA, and others. Some of these programs will be either closed- source or open-source. For additive manufacturing to be successful, an engineer or artist working with several computers will need to be proficient in using multiple operating systems. With these CAD tools and user experiences, it will be possible to produce a variety of complex 3D product models. The amount of material a 3D printer will take and the time it will require will be important factors influencing the additive manufacturing process.

Cross-Linking-Integrated Sequential Deposition: A Method for Efficient and Reproducible Bulk Heterojunctions in Organic Solar Cells.

The formation of bulk heterojunctions (BHJs) through sequential deposition (SqD) of polymer donor and nonfullerene acceptor (NFA) solutions offers advantages over the widely used single-step deposition of polymer:NFA blend solutions (BSD). To enhance the application of SqD in organic solar cell production, it is crucial to improve reproducibility and stability while maintaining a high efficiency. This study introduces a novel method termed cross-linking-integrated sequential deposition (XSqD) for fabricating efficient and reproducible BHJs. In this method, polymers are cross-linked using efficient 2Bx-4EO or 2Bx-8EO cross-linkers, which enhance the solvent resistance of the polymer donor layer against the solvents used for NFAs. This approach addresses the challenge of selecting a suitable solvent for NFAs, a major obstacle in SqD-processed OSCs. The utilization of 2Bx-4EO in XSqD leads to a significant increase in reproducibility compared to that of conventional SqD, coupled with a high-power conversion efficiency (PCE) of 14.1%. Furthermore, XSqD devices exhibit superior stability, showing only 1% and 6% reductions in their initial PCE after thermal stress at 80 and 120 °C for 50 h, respectively.

Plasma-chamber wall interaction and its impact on polymer deposition in inductively-coupled C4F8/Ar plasmas

Plasma processing chambers, key tools in semiconductor device fabrication, must be meticulously maintained to ensure tool-to-tool matching. Processing chamber walls are liable to contamination with fluorocarbon (CxFy) film, which acts as a source and/or sink for active species during plasma processes. This contamination potentially affects processing quality and alters the plasma properties, increasing deviations between processing chambers. However, quantitative studies on the impact of wall contamination on the substrate deposition outcomes have been limited. Additionally, spatially resolved investigations are crucial for understanding the plasma-wall interaction. Therefore, this study evaluated the influence of polymer (CxFy) film wall contamination on plasma deposition via various plasma diagnostics and surface analyses. When the chamber inner wall was coated with polymer film, the thickness, surface roughness, and chemical composition of the deposited film on the bottom substrate were more uniform. These results were linked to alterations in the uniformity of active species in the plasma, such as CF2 and F, resulting from interaction with the polymer film on the wall's surface. The C–Fx and C–CFx composition ratios in the wall-coated films dramatically reduced, indicating that this film supplied the depositing precursors to the plasma. These results suggest that controlling the chamber wall conditions is important to maintain tool-to-tool matching and modulate the processing performance.

Towards mass-production of ion-selective electrodes by spotting: Optimization of membrane composition and real-time tracking of membrane drying

Solid-contact ion-selective electrodes present tools for rapid assessment of charged species within a vast number of samples. Commercially available point-of-care electrochemical sensing systems are most often produced by screen-printing. However, this method is not applicable to polymeric membrane deposition, due to the mismatch of the membrane physical characteristics to those intended for screen printing. Herein, an industrial automated dispensing machine was used for fast and controlled deposition of small volumes of ion-selective membrane. Compared to the previously published literature, the dry solute membrane content was not altered. Rather, we optimized the solvents for the ISM preparation, thus significantly lowering the required overall number of membrane deposition steps. It was shown that dry membrane uniformity strongly depends on the solvent carrier system, with the best uniformity for the membrane prepared in a solvent mixture consisting of equal volumes of THF and cyclohexanone. The volume of a single membrane deposit (spot) was estimated based on colorimetric absorbance measurements to be 0.20 μL. Already with a single spot of the ion-selective membrane, an adequate potentiometric response to potassium ions was obtained, supporting the efficiency of the production technique. Evaporative membrane drying was investigated for the first time using time-resolved impedance spectroscopy, giving useful information on the influence of the solvent composition to the characteristics of the evaporative time profiles. With this approach, the overall production and drying of the described devices takes less than 30 min.

Long-Lasting, Transparent Antibacterial Shield: A Durable, Broad-Spectrum Anti-Bacterial, Non-Cytotoxic, Transparent Nanocoating for Extended Wear Contact Lenses.

The increasing incidence of serious bacterial keratitis, a sight-threatening condition often exacerbated by inadequate contact lens (CLs) care, highlights the need for innovative protective technology. This study introduces a long-lasting antibacterial, non-cytotoxic, transparent nanocoating for CLs via a solvent-free polymer deposition method, aiming to prevent bacterial keratitis. The nanocoating comprises stacked polymer films, with poly(dimethylaminomethyl styrene-co-ethylene glycol dimethacrylate) (pDE) as a biocompatible, antibacterial layer atop poly(2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane) (pV4D4) as an adhesion-promoting layer. The pD6E1-grafted (g)-pV4D4 film shows non-cytotoxicity toward two human cell lines and antibacterial activity of >99% against four bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), an antibiotic-resistant bacteria and Pseudomonas aeruginosa, which causes ocular diseases. Additionally, the film demonstrates long-lasting antibacterial activity greater than 96% against MRSA for 9 weeks in phosphate-buffered saline. To the best knowledge, this duration represents the longest reported long-term stability with less than 5% decay of antibacterial performance among contact-killing antibacterial coatings. The film exhibits exceptional mechanical durability, retaining its antibacterial activity even after 15 washing cycles. The pD6E1-g-pV4D4-coated CL maintains full optical transmittance compared to that of pristine CL. It is expected that the unprecedentedly prolonged antibacterial performance of the coating will significantly alleviate the risk of infection for long-term CL users.

Bioinspired Nanostructures by Soft‐Template Electropolymerization from Di‐Substituted Triphenylamine

AbstractWe report a bioinspired approach to tune surface nanostructures by soft‐template electropolymerization in micellar conditions. Monomers highly favoring π‐stacking interactions are particularly interesting for favoring the polymer deposition in one direction. Here, original triphenylamine‐based monomers di‐substituted by thiophene and carbazole are investigated. Conjugated building blocks monomers are tested to favor deposition vs polymerization, even if the monomers are not perfectly planar. The carbazole derivatives have a much higher electrodeposition capacity than the thiophene derivatives, which is unexpected if thiophene and carbazole are taken alone. Moreover, in all electrodeposited films, monomer seems to be present as shown by cyclic voltammetry experiments, confirming previous works. The amount of monomer vs oligomers is highly dependent on the investigated monomer. For the resulting surface structures, hollow spheres and nanoribbons are particularly formed with some investigated monomers by cyclic voltammetry while nanotubes are observed at constant potential. The formation of nanotubes indicates a polymer growth more favored in one direction. These surfaces are less hydrophobic (water contact angle up to 111.5°) compared to films with spherical nanoparticles but these results can be explained only by the presence of air inside the surface roughness.

Molecularly Imprinted Microspheres in Active Compound Separation from Natural Product.

Molecularly Imprinted Microspheres (MIMs) or Microsphere Molecularly Imprinted Polymers represent an innovative design for the selective extraction of active compounds from natural products, showcasing effectiveness and cost-efficiency. MIMs, crosslinked polymers with specific binding sites for template molecules, overcome irregularities observed in traditional Molecularly Imprinted Polymers (MIPs). Their adaptability to the shape and size of target molecules allows for the capture of compounds from complex mixtures. This review article delves into exploring the potential practical applications of MIMs, particularly in the extraction of active compounds from natural products. Additionally, it provides insights into the broader development of MIM technology for the purification of active compounds. The synthesis of MIMs encompasses various methods, including precipitation polymerization, suspension polymerization, Pickering emulsion polymerization, and Controlled/Living Radical Precipitation Polymerization. These methods enable the formation of MIPs with controlled particle sizes suitable for diverse analytical applications. Control over the template-to-monomer ratio, solvent type, reaction temperature, and polymerization time is crucial to ensure the successful synthesis of MIPs effective in isolating active compounds from natural products. MIMs have been utilized to isolate various active compounds from natural products, such as aristolochic acids from Aristolochia manshuriensis and flavonoids from Rhododendron species, among others. Based on the review, suspension polymerization deposition, which is one of the techniques used in creating MIPs, can be classified under the MIM method. This is due to its ability to produce polymers that are more homogeneous and exhibit better selectivity compared to traditional MIP techniques. Additionally, this method can achieve recovery rates ranging from 94.91% to 113.53% and purities between 86.3% and 122%. The suspension polymerization process is relatively straightforward, allowing for the effective control of viscosity and temperature. Moreover, it is cost-effective as it utilizes water as the solvent.

Strategies for alkali-free synthesis, surface modification, and electrophoretic deposition of composite films for biomedical applications

This investigation addresses increasing interest in composites for biomedical applications and advanced methods for their synthesis and electrophoretic deposition (EPD). The feasibility of preparation of hydroxyapatite (HA), titania and zirconia particles using branched polyethylenimine polymer (BPEI) or L-arginine amino acid as organic alkalizers is demonstrated. In this new approach, BPEI and L-arginine are used as alkalizers-capping agents instead of inorganic alkalis. The use of BPEI facilitates synthesis of HA nanorods with reduced size. This approach opens an avenue for the fabrication of nanoparticles of other functional inorganic materials using alkalizers-capping agents. It offers advantages of simple procedure, environmental benefits and improved control of particle size. Composite films are obtained by cathodic EPD using linear polyethylenimine (LPEI) as a charging and film-forming agent. A conceptually new approach is developed for anodic EPD of alginic acid polymer (AlgH) and composite films containing drug molecules in AlgH matrix. This strategy involves the use of L-arginine as an alkalizer for solubilization of drugs, which exhibit poor solubility in water. AlgH and drug molecules are solubilized in water and deposited by anodic EPD. Testing results confirm the fabrication of composite films, containing drug molecules. This method allows reduced gas evolution at the electrode, elimination of film porosity, improved stabilization of bioceramic particles in polymer solutions and facilitates composite film formation from stable suspensions. The deposition methods developed in this investigation can be used for deposition of other cationic and anionic polymers and their co-EPD with bioceramics, drugs and other functional materials.

The structure and interaction of polymers affects secondary cell wall banding patterns in Arabidopsis.

Xylem tracheary elements (TEs) synthesize patterned secondary cell walls (SCWs) to reinforce against the negative pressure of water transport. VASCULAR-RELATED NAC-DOMAIN 7 (VND7) induces differentiation, accompanied by cellulose, xylan, and lignin deposition into banded domains. To investigate the effect of polymer biosynthesis mutations on SCW patterning, we developed a method to induce tracheary element transdifferentiation of isolated protoplasts, by transient transformation with VND7. Our data showed that proper xylan elongation is necessary for distinct cellulose bands, cellulose-xylan interactions are essential for coincident polymer patterns, and cellulose deposition is needed to override the intracellular organization that yields unique xylan patterns. These data indicate that a properly assembled cell wall network acts as a scaffold to direct polymer deposition into distinctly banded domains. We describe the transdifferentiation of protoplasts into TEs, providing an avenue to study patterned SCW biosynthesis in a tissue-free environment and in various mutant backgrounds.

Enhancement in the Stability of Porous Silicon Using Electrochemical Grafting of Polymer 2,6 Dihydroxy Naphthalene

While there have been many advancements related to porous silicon, the reactivity of silicon with the ambient (particularly in environments with oxygen and humidity) has limited its use and integration in a wide variety of applications. Therefore, it is important to passivate the surface of nanostructured/porous silicon. To this end, there have been many reports in literature where passivation of bare (or unpassivated) porous silicon (UPSi) surface has been performed using gas phase techniques (thermal carbonization) and solution-based methods. In this work, we have studied the influence of the electrochemical deposition of polymer 2,6 dihydroxynaphthalene (2,6 DHN), in enhancing the stability of porous silicon surfaces.Porous silicon was synthesized by the electrochemical etching of pre-cleaned p-type silicon substrates with resistivity of about 0.001 Ω-cm to 0.005 Ω-cm, in a PTFE cell that we have fabricated, with 48% HF and ethanol mixture (7:3) as the electrolyte solution, at a current density of about 1.08 A/cm². The polymer solution used for electrodeposition was prepared as a solution of 1 mM 2,6-dihydroxy naphthalene (2,6-DHN) in 100 mL of 1x phosphate buffer solution, which was vacuum infiltrated in the synthesized porous silicon and electrodeposited on the same with the standard three electrodes chronopotentiometry method, at a constant current density of about 2 mA/cm² for 120 seconds. Electrodeposited porous silicon was kept on the hot plate for 10 min at 220℃, followed by a thermal treatment at 600℃, for 180 min, in the presence of N2 flow (1 L/min).The surface morphology of the unpassivated porous silicon (UPSi) and passivated porous silicon (PPSi) are shown in the insets of Fig. 1(a) and (b), respectively. This suggests the presence of an incredibly thin coating of the polymer on the pore walls. The pores in, both, unpassivated and passivated porous silicon samples (UPSi and PPSi) remained open and unobstructed, offering a uniform distribution of pores with sizes ranging between 5 nm and 20 nm.To perform a corrosion test of the UPSi and PPSi, we look at these layers after they have been exposed to 1 M NaOH aqueous solution, for different time durations. We have seen the formation of a spontaneous bubble on the surface of the UPSi sample during the test. To this end, we have observed visible and morphological changes of both UPSi and PPSi samples after the corrosion stability test for 5 seconds and 120 minutes, respectively, as seen in Fig. 1(a) to (h). Due to the very high internal area and the hydrogen-terminated surface, in an aqueous solution, UPSi is oxidized by water at room temperature and degrades. In comparison, the PPSi sample is stable for more than 120 minutes.Electrochemical characterisation of UPSi and PPSi was performed in a 10 mM NaCl aqueous electrolyte with a three-electrode cyclic voltammetry (C-V) setup. C-V measurements of the UPSi sample show strong redox reaction in the potential window of 0 V to 1 V, whereas, the PPSi sample shows a nearly constant charging current response in the potential window of -1 V to 1 V, as shown in Fig. 1(i). These results emphasize that the passivation of porous silicon using 2,6 DHN polymer makes it more stable and less reactive in an aqueous medium. Figure 1

Patient-reported outcomes and functional assessments of patients with Alkaptonuria in a 3-year Nitisinone treatment trial

Alkaptonuria is a rare disorder of tyrosine catabolism caused by deficiency of homogentisate 1,2-dioxygenase that leads to accumulation of homogentisic acid (HGA). Deposition of HGA-derived polymers in connective tissue causes progressive arthropathy of the spine and large joints, cardiac valvular disease, and genitourinary stones beginning in the fourth decade of life. Nitisinone, a potent inhibitor of the upstream enzyme, 4-hydroxyphenylpyruvate dioxygenase, dramatically reduces HGA production. As such, nitisinone is a proposed treatment for alkaptonuria. A randomized clinical trial of nitisinone in alkaptonuria confirmed the biochemical efficacy and tolerability of nitisinone for patients with alkaptonuria but the selected primary outcome did not demonstrate significant clinical benefit. Given that alkaptonuria is a rare disease with slow progression and variable presentation, identifying outcome parameters that can detect significant change during a time-limited clinical trial is challenging. To gain insight into patient-perceived improvements in quality of life and corresponding changes in physical function associated with nitisinone use, we conducted a post-hoc per protocol analysis of patient-reported outcomes and a functional assessment. Analysis revealed that nitisinone-treated patients showed significant improvements in complementary domains of the 36-Item Short-Form Survey (SF-36) and 6-min walk test (6MWT). Together, these findings suggest that nitisinone improves both quality of life and function of patients with alkaptonuria. The observed trends support nitisinone as a therapy for alkaptonuria.

3-Methyl Thiophene-Modified Boron-Doped Diamond (BDD) Electrodes as Efficient Catalysts for Phenol Detection-A Case Study for the Detection of Gallic Acid in Three Specific Tea Types.

Polymer modification has been established as a cost-effective, simple, in situ method for overcoming some of the inherent disadvantages of boron-doped diamond (BDD) electrodes, and its application has been extended to reliable, low-cost environmental monitoring solutions. The present review focuses on modifying BDD electrodes with semi-conductive polymers acting as redox mediators. This article reports on the development of a 3-methyl thiophene-modified boron-doped diamond (BDD/P3MT) sensor for the electrochemical determination of total phenolic compounds (TPCs) in tea samples, using gallic acid (GA) as a marker. GA is a significant polyphenol with various biological activities, making its quantification crucial. Thus, a simple, fast, and sensitive GA sensor was fabricated using the electroanalytical square wave voltammetry (SWV) technique. The sensor utilizes a semi-conductive polymer, 3-methyl thiophene, as a redox mediator to enhance BDD's sensitivity and selectivity. Electrochemical synthesis was used for polymer deposition, allowing for greater purity and avoiding solubility problems. The BDD/P3MT sensor exhibits good electrochemical properties, including rapid charge transfer and a large electrochemical area, enabling GA detection with a limit of detection of 11 mg/L. The sensor's response was correlated with TPCs measured by the Folin-Ciocalteu method. Square wave voltammetry (SWV) showed a good linear relationship between peak currents and GA concentrations in a wide linear range of 3-71 mg/L under optimal conditions. The BDD/P3MT sensor accurately measured TPCs in green tea, rooibos tea, and black tea samples, with green tea exhibiting the highest TPC levels. The results demonstrate the potential of the modified BDD electrode for the rapid and accurate detection of phenolic compounds in tea, with implications for quality control and antioxidant activity assessments. The prolific publications of the past decade have established BDD electrodes as robust BDD sensors for quantifying polyphenols. Fruits, vegetables, nuts, plant-derived beverages such as tea and wine, traditional Eastern remedies and various herbal nutritional supplements contain phenolic chemicals. The safety concerns of contaminated food intake are significant health concerns worldwide, as there exists a critical nexus between food safety, nutrition, and food security. It has been well established that green tea polyphenol consumption promotes positive health effects. Despite their potential benefits, consuming high amounts of these polyphenols has sparked debate due to concerns over potential negative consequences.

3D porous PEDOT/MXene scaffold toward high-performance supercapacitors

3D architectures of conductive polymer, especially PEDOT hold great promise in energy storage and conversion fields. However, the facile construction of 3D PEDOT and its functionalization have still been challenges due to its poor processability. Herein, the fabrication of 3D porous PEDOT:PSS and its functionalization with MXene are realized synchronously through a simple and low-cost self-assembly process. The prominent capacitive performance of MXene, excellent chemical stability of PEDOT:PSS and 3D porous architecture with inhibited aggregation of MXene nanosheets, large amount of active sites, and electrolyte storage chamber endow the PEDOT/MXene-based porous structure with superior capacitive performance than individual PEDOT:PSS or MXene porous and flat structures. Furthermore, the PEDOT/MXene-based porous structure can be applied as a flexible scaffold for the deposition of conductive polymer to construct excellent electrodes for supercapacitors (SCs). When polypyrrole (PPy) is deposited, the prepared porous PEDOT:PSS/MXene/PPy electrode exhibits a high gravimetric specific capacitance of 345 F g−1 at a current density of 0.5 A g−1 and a remarkable capacitance retention of 89 % over 5000 cycles. Based on it, an asymmetric supercapacitor (ASC) with a high energy density of 56.34 Wh kg−1 at the power density of 120 W kg−1, and a capacitance retention of 75 % after 5000 cycles is developed. Besides, the porous PEDOT:PSS/MXene/PPy can be constructed on various substrates in any pattern with high design freedom, thus enabling customizable electrochemical performance. When constructing on a flexible substrate, excellent deformation-tolerant performance is shown. This work provides a high-performance electrode for SCs, as well as a universal route for the construction and functionalization of 3D PEDOT-based structures.

MeNPs-PEDOT Composite-Based Detection Platforms for Epinephrine and Quercetin.

The development of low-cost, sensitive, and simple analytical tools for biomolecule detection in health status monitoring is nowadays a growing research topic. Sensing platforms integrating nanocomposite materials as recognition elements in the monitoring of various biomolecules and biomarkers are addressing this challenging objective. Herein, we have developed electrochemical sensing platforms by means of a novel fabrication procedure for biomolecule detection. The platforms are based on commercially available low-cost conductive substrates like glassy carbon and/or screen-printed carbon electrodes selectively functionalized with nanocomposite materials composed of Ag and Au metallic nanoparticles and an organic polymer, poly(3,4-ethylenedioxythiophene). The novel fabrication method made use of alternating currents with controlled amplitude and frequency. The frequency of the applied alternating current was 100 mHz for the polymer deposition, while a frequency value of 50 mHz was used for the in situ electrodeposition of Ag and Au nanoparticles. The selected frequency values ensured the successful preparation of the composite materials. The use of readily available composite materials is intended to produce cost-effective analytical tools. The judicious modification of the organic conductive matrix by various metallic nanoparticles, such as Ag and Au, extends the potential applications of the sensing platform toward a range of biomolecules like quercetin and epinephrine, chosen as benchmark analytes for proof-of-concept antioxidant and neurotransmitter detection. The sensing platforms were tested successfully for quercetin and epinephrine determination on synthetic and real samples. Wide linear response ranges and low limit-of-detection values were obtained for epinephrine and quercetin detection.

NO-cGMP-K+ Channels Pathways Participate in the Antihypertensive Effects of Attalea phalerata Martius ex Spreng Oil-Loaded Nanocapsules.

Attalea phalerata Martius ex Spreng is a palm tree that is widely distributed in the Central-West region of Brazil. In this study, we investigated whether the oil-loaded nanocapsules of A. phalerata (APON) have acute and long-lasting antihypertensive effects in male spontaneously hypertensive rats (SHR), as well as explored the underlying molecular mechanisms. APON was prepared using the interfacial polymer deposition method. The particle size, polydispersity index, and zeta potential were investigated using dynamic and electrophoretic light scattering. The antihypertensive effects of APON (administered at doses of 1, 3, and 10 mg/kg) were evaluated after acute intraduodenal administration and after 7 days of oral treatment. To investigate the molecular pathways involved, we used pharmacological antagonists and inhibitors that target prostaglandin/cyclic adenosine monophosphate, nitric oxide/cyclic guanosine monophosphate, and potassium channels. Both acute and prolonged administration of APON (at doses of 3 and 10 mg/kg) resulted in a significant reduction in systolic, diastolic, and mean arterial pressure. Prior treatment with a non-selective nitric oxide synthase inhibitor (Nω-nitro-L-arginine methyl ester), guanylyl cyclase inhibitor (methylene blue), or non-selective calcium-sensitive K+ channel blocker (tetraethylammonium) abolished the antihypertensive effects of APON. Our study showed that A. phalerata oil-loaded nanocapsules have a significant antihypertensive effect in SHR after both short-term and long-term (7-day) use. This effect seems to rely on the vascular endothelium function and involves the NO-cGMP-K+ channel pathway. This research suggests a new direction for future studies to definitively prove the therapeutic benefits of APON in treating cardiovascular disease.

Immunomodulatory and Anticancer Effects of Fridericia chica Extract-Loaded Nanocapsules in Myeloid Leukemia.

Nanocapsules provide selective delivery and increase the bioavailability of bioactive compounds. In this study, we examined the anticancer and immunomodulatory potential of Fridericia chica (crajiru) extract encapsulated in nanocapsules targeting myeloid leukemias. Nanocapsules containing crajiru (nanocapsules-CRJ) were prepared via interfacial polymer deposition and solvent displacement. Size and polydispersity were measured by dynamic light scattering. Biological assays were performed on leukemia cell lines HL60 and K562 and on non-cancerous Vero cells and human PBMC. The anticancer activity was evaluated using cytotoxicity and clonogenic assays, while the immunomodulatory activity was evaluated by measuring the levels of pro- and anti-inflammatory cytokines in PBMC supernatants treated with concentrations of nanocapsules-CRJ. Nanocapsules-CRJ exhibited significant cytotoxic activity against HL60 and K562 cells at concentrations ranging from 0.75 to 50 μg/mL, with the greatest reductions in cell viability observed at 50 μg/mL (p < 0.001 for HL60; p < 0.01 for K562), while not affecting non-cancerous Vero cells and human PBMCs. At concentrations of 25 μg/mL and 50 μg/mL, nanocapsules-CRJ reduced the formation of HL60 and K562 colonies by more than 90% (p < 0.0001). Additionally, at a concentration of 12 μg/mL, nanocapsules-CRJ induced the production of the cytokines IL-6 (p = 0.0002), IL-10 (p = 0.0005), IL-12 (p = 0.001), and TNF-α (p = 0.005), indicating their immunomodulatory potential. These findings suggest that nanocapsules-CRJ hold promise as a potential therapeutic agent with both cytotoxic and immunomodulatory properties.

Electrochemical visualization of latent fingerprints using polyphenazine dyes on brass cartridges

This work is focused on the visualization of latent fingerprints left on unfired brass cartridges. Polymer films were prepared from 2 mM neutral red or 5 mM toluidine blue using two different electrochemical methods (cyclic voltammetry or chronoamperometry) with relatively short polymerization times. The conditions for the deposition of conductive polymers, poly(neutral red) and poly(toluidine blue), from a neutral medium (phosphate buffer with 0.1 M KNO3 or 0.1 M KNO3, respectively) were optimized to produce high-quality visualization of the remaining fingerprints on the brass substrates. The surface morphology and quality of the polymer films after the electrochemical deposition of both polyphenazine dyes were characterized by stereomicroscope. Phenazine dyes, which were used for the visualization of fingerprints, have been shown to provide different degrees of homogeneity in the deposited film. Furthermore, the dependence of the stability of the monomer solutions on their age, use, and storage conditions are discussed. Finally, a methodology is proposed for how to apply this technique of visualizing latent fingerprints with observed details of papillary lines in forensic practice.Graphical abstract