Catechol Functionality Research Articles

Flow and On-Water Synthesis and Cancer Cell Cytotoxicity of Caffeic Acid Phenethyl Amide (CAPA) Derivatives.

Caffeic acid phenethyl ester (CAPE) is a phenolic natural product with a wide range of biological activities, including anticancer activity; however, the ester group of CAPE is metabolically labile. The corresponding amide, CAPA, has improved metabolic stability but limited anticancer activity relative to CAPE. We report the synthesis using flow and on-water Wittig reaction approaches of five previously reported and five novel CAPA analogues. All of these analogues lack the reactive catechol functionality of CAPA and CAPE. Cytotoxicity studies of CAPE, CAPA, and these CAPA analogues in HeLa and BE(2)-C cells were carried out. Surprisingly, we found that CAPA is cytotoxic against the neuroblastoma BE(2)-C cell line (IC50 = 12 µM), in contrast to the weak activity of CAPA against HeLa cells (IC50 = 112 µM), and the literature reports of the absence of activity for CAPA against a variety of other cancer cell lines. One novel CAPA analogue, 3f, was identified as having cytotoxic activity similar to CAPE in HeLa cells (IC50 = 63 µM for 3f vs. 32 µM for CAPE), albeit with lower activity against BE(2)-C cells (IC50 = 91 µM) than CAPA. A different CAPA analogue, 3g, was found to have similar effects against BE(2)-C cells (IC50 = 92 µM). These results show that CAPA is uniquely active against neuroblastoma cells and that specific CAPA analogues that are predicted to be more metabolically stable than CAPE can reproduce CAPA's activity against neuroblastoma cells and CAPE's activity against HeLa cells.

Tuning interfacial viscoelasticity of catechol-functionalized alginate by pH-responsive covalent network for stabilizing high internal phase pickering emulsions

Polysaccharide-based soft particles have wide applications in preparing high phase Pickering emulsions (HIPPEs) because of their adjustable interfacial properties, which can advance the stability of HIPPEs by strengthening their interfacial viscoelasticity. Nevertheless, there is limited research on the interfacial viscoelasticity of soft particles regarding the stability of HIPPEs. We synthesized Alg-CA soft particles by the Ugi reaction, featuring catechol functionality and amphiphilic alginate. These particles can self-assemble under pH stimulation, resulting in a network structure that impacts the interfacial viscoelasticity of HIPPEs. We investigated the relationship between self-assembled microstructure and interfacial viscoelasticity using transmission electron microscopy (TEM) and rheometry. The study indicates that the Alg-CA solution produced a compact network structure at a pH level of 3, leading to the formation of highly stable HIPPEs (with a viscosity of approximately 1000 Pa·s). Additionally, by utilizing emulsion templates, 3D network aerogels with pH-sensitive, consistent microstructures may be developed, which presents a promising approach for designing and producing aerogels with distinct microporous architectures.

High-sensitivity wearable multi-signal sensor based on self-powered MXene hydrogels

Developing high-performance wearable sensors with multi-sensing capabilities for different signals such as temperature, human motion and physiological signals remains a challenge. In this report, a novel catechol functionalization of PVA-CA/Poly(N-acryloyl glycinamide)/MXene hydrogels(PcNA-M) was fabricated by combining the thermosensitivity of Poly(N-acryloyl glycinamide)(PNAGA) hydrogel and the self-powered properties of the catechol functionalization of PVA(Pc)/MXene hydrogels. The mixing ratio of PNAGA and Pc was adjusted to impart the resulting PcNA-M with good tensile, compression, rebound properties, rapid self-healing and temperature sensing properties. In addition, the conductivity of the hydrogel was found to have contributions from ionic and electrical conductivity. To produce different forms of electrical signals for different signal sources, the PcNA-M sensor was utilized to monitor the resistive and voltage signals during body movements, switching temperature and handwriting motion. The PcNA-M sensor exhibits high sensitivity, identifiability, and reliability in applications of self-powered wearable sensors, and demonstrates great prospects in the field of low-frequency mechanical energy harvesting. This study opens a new possibility for wearable self-powered multi-signal sensors to monitor different signals related to human motion.

Boronic acid conjugated polyacrylate coating: A strategy for material-independent surface functionalization

Most biomaterial surfaces are non-functional, which inevitably requires additional functionalization steps. However, these steps are typically material-dependent; only a few limited methods, such as catechol functionalization using polydopamine coating, have been reported as material-independent for surface modification. In this study, we developed a one-step boronic acid surface functionalization method utilizing a polyacrylate that contains both butyl and boronic acid groups. The butyl group exhibits strong interfacial adhesion due to its low glass transition temperature (Tg), which maintains its softness and tackiness, thereby facilitating attachment to various substrates. Meanwhile, the boronic acid acts as a functional group for surface modification. Various substrates, including polymers, metals, and ceramics widely used in implants, were successfully coated with the polyacrylate, bestowing boronic acid functionality on the surface. Given that boronic acid is one of the most widely applied functional groups in the biomaterials field, we anticipate that our methodology will be applicable in developing various biomedical applications such as antifouling coatings, biosensors, and bioadhesives.

Characterization of heteromeric state of novel functional catechol 1,2-dioxygenase using small-angle X-ray scattering

Characterization of heteromeric state of novel functional catechol 1,2-dioxygenase using small-angle X-ray scattering

A comparative study on surface-engineered nanoceria using a catechol copolymer design: colloidal stability vs. antioxidant activity.

Nanoceria (NC) are widely studied as potent nanozyme antioxidants, featuring unique multifunctional, self-regenerative, and high-throughput enzymatic functions. However, bare NC are reported to show poor colloidal stability in biological media. Despite this, the nexus between colloidal stability and antioxidant activity has rarely been assessed. Here, a library of three copolymeric stabilising agents was synthesised, each consisting of hydrophilic poly(oligo(ethylene glycol) methyl ether methacrylate) brushes (P(OEGMA)) and a novel catechol anchoring block, and used for surface engineering of NC. The colloidal stability of the surface-engineered NC was assessed in phosphate buffered saline (PBS) by monitoring their precipitation via UV-Vis spectrophotometry, and their catalase (CAT)- and superoxide dismutase (SOD)-like activities were analysed using fluorospectrophotometry. The obtained results indicate that P(OEGMA) coating improves colloidal stability of NC over 48 h, highlighting the stable attachment of catechol functionalities to the surface of NC. In addition, X-ray photoelectron spectroscopy (XPS) indicates that the catechol functionalities lead to an increase in Ce3+/Ce4+ ratio and the concentration of oxygen vacancies, depending on the number of catechol units. Altogether, surface engineering of NC optimally results in an increase in CAT- and SOD-like activities by, respectively, 41% (=57.7% H2O2 elimination) and 78% (=78.0% O2˙- elimination) relative to bare NC, signifying a positive correlation between colloidal stability and antioxidant activity of the NC nanozymes.

Designing anti(-bio)fouling membranes with synergistic grafting of quaternized and zwitterionic polymers through surface initiated atom transfer radical polymerization

Membrane-based filtration technologies have significant potential to address the global problem of freshwater scarcity. However, fouling, caused by nonspecific adsorption of foulants and microbiological growth during filtration, remains a considerable concern. To address this, a rational surface design method comprising bifunctional coating with both defensive and attacking techniques has been devised, which can successfully decrease fouling and biofouling. To generate a bifunctional membrane, a single-step surface-initiated atom-transfer radical polymerization (SI-ATRP) of monomers with zwitterionic and quaternized imidazolium moieties was done on a polydopamine (PDA) primed polyvinylidene fluoride (PVDF) membrane. The PDA layer’s catechol functionalities provided abundant anchoring sites, allowing the grafting of a dense polymer layer on the membrane. The addition of active zwitterionic and quaternized imidazolium moieties in the grafted polymer chains resulted in very low fouling and microbiological species death. Extensive antifouling studies revealed that the functionalized membranes have excellent flux recovery (>93%), low irreversible fouling (<8.5%), and long-term filtration stability. This surface functionalization strategy based on a bifunctional unit represents a significant advancement in fouling mitigation by minimizing membrane-foulant interactions and killing adhered bacteria, with the potential to significantly broaden the range of membrane-based filtration applications and contribute to more efficient and sustainable water purification processes.

Catechol Conjugation for Bioadhesion in Photo-Cross-Linkable Biomaterials

Inspired by mussel adhesion, catechol functionalization of different biomacromolecules has become a popular technique to impart adhesion to biomaterials. However, the bioadhesion capacity of catechol motifs in hydrogels that cross-link through free-radical-based systems is debated. Here, we revisit the bioadhesion efficacy of catechol functionalization in methacryloyl-modified photo-cross-linkable biomaterials. For this purpose, gelatin biomolecules functionalized with caffeic acid (CA) and methacryloyl groups are cross-linked using UV light to assess their cross-linking and bioadhesion. Despite the typical emphasis on wet adhesion of catecholic biomaterials, samples with larger catechol content showed lower adhesion strength, particularly when bioadhesives are cross-linked in situ as injectable sealants. Cross-linking was found to decay toward the interface with the substrates as more catechol groups are introduced to the hydrogels, which further undermines hydrogel integrity and adhesive bonds. Finally, cytotoxic and immunostimulatory effects associated with the catechol groups are evaluated for their translational potential in clinical applications.

Poly-Catecholic Functionalization of Biomolecules for Rapid Gelation, Robust Injectable Bioadhesion, and Near-Infrared Responsiveness.

Mussel-inspired catechol-functionalization of degradable natural biomaterials has garnered significant interest as an approach to achieve bioadhesion for sutureless wound closure. However, conjugation capacity in standard coupling reactions, such as carbodiimide chemistry, is limited by low yield and lack of abundant conjugation sites. Here, a simple oxidative polymerization step before conjugation of catechol-carrying molecules (i.e., 3,4-dihydroxy-l-phenylalanine, l-DOPA) as a potential approach to amplify catechol function in bioadhesion of natural gelatin biomaterials is proposed. Solutions of gelatin modified with poly(l-DOPA) moieties (GelDOPA) are characterized by faster physical gelation and increased viscosity, providing better wound control on double-curved tissue surfaces compared to those of l-DOPA-conjugated gelatin. Physical hydrogels treated topically with low concentrations of NaIO4 solutions are crosslinked on-demand via through-thickness diffusion. Poly(l-DOPA) conjugates enhance crosslinking density compared to l-DOPA conjugated gelatin, resulting in lower swelling and enhanced cohesion in physiological conditions. Together with cohesion, more robust bioadhesion at body temperature is achieved by poly(l-DOPA) conjugates, exceeding those of commercial sealants. Further, poly(l-DOPA) motifs introduced photothermal responsiveness via near-infrared (NIR) irradiation for controlled drug release and potential applications in photothermal therapy. The above functionalities, along with antibacterial activity, render the proposed approach an effective biomaterial design strategy for wound closure applications.

Bioinspired fabrication of self-recovery, adhesive, and flexible conductive hydrogel sensor driven by dynamic borate ester bonds and tannic acid-mediated noncovalent network

Conductive polymer hydrogels have received enormous attention because of their promising applications in healthcare monitoring, soft robots, and wearable electronics. Development of hydrogel sensor with strong mechanical properties, excellent sensing capabilities, self-healing and adhesive properties is highly desirable and still remains a critical challenge. Herein, we report a borax crosslinked flexible hydrogel based on polyvinyl alcohol (PVA), sodium alginate (SA), and tannic acid (TA) modify barium titanate (BT) nanoparticles (T@BT) via a facile one-pot method. The crosslinking network was formed by dynamic reversible borate ester bond and TA-enabled interactions including hydrogen bonds and coordination bonds, which endowed the hydrogel with excellent self-healing and mechanical properties. Meanwhile, the combination of functional catechol groups in TA with the significantly improved cohesion of the hydrogel enabled the hydrogel to exhibit strong and residue-free adhesion to a variety of inorganic and organic materials. The adhesion strength to wood was up to 67.5 kPa. Furthermore, the addition of the T@BT not only rendered the hydrogel highly conductive (1.91 S/m) and sensitive for sensing, but also synergistically enhanced the toughness (587.1 KJ/m3) of the hydrogel. This work provides new ideas for the preparation of multifunctional conductive hydrogels.

Catechol redox couple functionalized metal-organic framework UiO-66-NH2 as an efficient catalyst for chromium ion sensor in water samples

Hexavalent chromium (Cr6+) is a major toxic pollutant than the trivalent (Cr3+) in water, which is challenging for selective Cr6+ detection in an acidic medium. Zirconium-cluster (Zr6) metal-organic frameworks (MOFs) are highly stable in acid medium, and their three-dimensional structures enable facile access to target analytes. However, non-electroactive metals and linkers within MOFs limit their electrochemical applications. Therefore, the purpose of the present study is an innovative diazotization of redox-active functional moiety on the non-electroactive MOF to electroactive MOF for electrocatalytic applications. Present work, post-synthetically diazotized UiO-66-NH2 MOF with redox-active catechol form UiO-66-NN-φ(OH)2. Phenolic groups in as-prepared UiO-66-NN-φ(OH)2 were revealed as excellent redox couple that was effectively used as an electrocatalytic Cr6+ sensor. The pKa (Brønsted acidities) of the Zr-η3-OH and functional catechol were estimated. To improve redox current, electrochemically reduced graphene oxide (ERGO) was used as a substrate for UiO-66-NN-φ(OH)2 MOF with the surface coverage (τ) of 6.63 × 10−10 mol cm−2. In contrast, the τ value of UiO-66-NN-φ(OH)2/glassy carbon (GC) electrode was 2.12 × 10−11 mol cm−2. The temperature effect on the redox chemistry of UiO-66-NN-φ(OH)2@ERGO/GC C–OH and Cr6+ was examined. The UiO-66-NN-φ(OH)2@ERGO/GC electrode operates in a wide Cr6+ concentration range (0.062–962 μM) with excellent sensitivity (0.211 μA μM−1), a low limit of detection (0.06 μM), and high specificity and storage stability. Finally, the innovative new UiO-66-NN-φ(OH)2@ERGO/GC was applied to actual tap waters containing Cr6+ and exhibited a wide recovery range that traditional ICP-AES validated.

A Straightforward Access to New Amides of the Melanin Precursor 5,6-Dihydroxyindole-2-carboxylic Acid and Characterization of the Properties of the Pigments Thereof.

We report herein an optimized procedure for preparation of carboxamides of 5,6-dihydroxyindole-2-carboxylic acid (DHICA), the main biosynthetic precursor of the skin photoprotective agents melanins, to get access to pigments with more favorable solubility properties with respect to the natural ones. The developed procedure was based on the use of a coupling agent (HATU/DIPEA) and required protection of the catechol function by easily removable acetyl groups. The O-acetylated compounds could be safely stored and taken to the reactive o-diphenol form just before use. Satisfactorily high yields (>85%) were obtained for all amides. The oxidative polymerization of the synthesized amides carried out in air in aqueous buffer at pH 9 afforded melanin-like pigmented materials that showed chromophores resembling those of DHICA-derived pigments, with a good covering of the UVA and the visible region, and additionally exhibited a good solubility in alcoholic solvents, a feature of great interest for the exploitation of these materials as ingredients of dermocosmetic formulations.

Novel Bio‐Based Catechol‐Containing Copolymers by Precision Polymerization of Caffeic Acid‐Derived Styrenes Using Ester Protection

Front Cover: Caffeic acid is a component of coffee beans and bears catechol functionality. In article number 2100378 by Kotaro Satoh and co-workers, a caffeic acid-derived styrene monomer is amenable to RAFT polymerization, which is one of the emerging methodologies for polymer synthesis. Combined with protection/deprotection processes, the polymerization results in welldefined functional block copolymers consisting of catechol-containing segments and acrylic segments.

Novel Adhesive Nanocarriers Based on Mussel-Inspired Polyglycerols for the Application onto Mucosal Tissues

A synthetic route for adhesive core-multishell (CMS) nanocarriers for application to the oral mucosa was established using mussel-inspired catechol moieties. The three CMS nanocarriers with 8%, 13%, and 20% catechol functionalization were evaluated for loading capacity using Nile red, showing an overall loading of 1 wt%. The ability of Nile red loaded and functionalized nanocarriers to bind to a moist mucosal surface was tested in two complementary adhesion assays under static and dynamic conditions using monolayers of differentiated gingival keratinocytes. Adhesion properties of functionalized nanocarriers were compared to the adhesion of the non-functionalized nanocarrier. In both assays, the CMS nanocarrier functionalized with 8% catechol exhibited the strongest adhesion compared to its catechol-free counterpart and the CMS nanocarriers functionalized with 13% and 20% catechol.

Synthesis and Validation of a Bioinspired Catechol-Functionalized Pt(IV) Prodrug for Preclinical Intranasal Glioblastoma Treatment.

Simple SummaryGlioblastoma (GB) is a type of brain cancer with a poor prognosis and few improvements in its treatment. One of the greatest difficulties in GB therapy lies in the fact that most of the drugs with high anticancer potential do not reach the brain and exert high therapeutic activity while minimizing side effects. To overcome these limitations, we focused on a catechol-based Pt(IV) prodrug (able to reverse cisplatin in a cellular environment) with the intention of repurposing Pt-based drugs as GB chemotherapeutic agents. Our in vitro results have corroborated the therapeutic effect of the synthesized complexes as comparable to cisplatin, and in vivo studies have demonstrated the potential of nose-to-brain delivery of this Pt(IV) prodrug for GB treatment.Glioblastoma is the most malignant and frequently occurring type of brain tumors in adults. Its treatment has been greatly hampered by the difficulty to achieve effective therapeutic concentration in the tumor sites due to its location and the blood–brain barrier. Intranasal administration has emerged as an alternative for drug delivery into the brain though mucopenetration, and rapid mucociliary clearance still remains an issue to be solved before its implementation. To address these issues, based on the intriguing properties of proteins secreted by mussels, polyphenol and catechol functionalization has already been used to promote mucopenetration, intranasal delivery and transport across the blood–brain barrier. Thus, herein we report the synthesis and study of complex 1, a Pt(IV) prodrug functionalized with catecholic moieties. This complex considerably augmented solubility in contrast to cisplatin and showed a comparable cytotoxic effect on cisplatin in HeLa, 1Br3G and GL261 cells. Furthermore, preclinical in vivo therapy using the intranasal administration route suggested that it can reach the brain and inhibit the growth of orthotopic GL261 glioblastoma. These results open new opportunities for catechol-bearing anticancer prodrugs in the treatment for brain tumors via intranasal administration.

Effect of Concrete Composition on the Thermodynamic Binding of Dopamine: A DFT Study.

Concrete has long been a standard in construction projects. However, increasing the binding of cement paste to the concrete aggregate (a collection of geological materials containing, e.g., gravel, sand, etc.) remains an open area of research, as this is a common failure point in concrete-based infrastructure. One solution is the application of an adhesive into the mix that not only is capable of binding under aqueous conditions but can aid in the binding of the aggregate to the cement paste. Bioinspired catecholic-type molecules have been shown to be an ultrastrong adhesive, even under wet conditions, and would, in principle, be an ideal candidate to use. In this study, we examine how dopamine (a molecule with a catechol functionality) binds to various oxides found in concrete mixtures. We find that dopamine binds preferentially to alkaline earth oxides; thus, for concrete mixtures rich in these minerals dopamine would be an ideal candidate for improved adhesion.

Synthesis and Cu(I)/Mo(VI) Reactivity of a Bifunctional Heterodinucleating Ligand on a Xanthene Platform.

In an effort to probe the feasibility of a model of Mo-Cu CODH (CODH = carbon monoxide dehydrogenase) lacking a bridging sulfido group, the new heterodinucleating ligand LH2 was designed and its Cu(I)/Mo(VI) reactivity was investigated. LH2 ((E)-3-(((5-(bis(pyridin-2-ylmethyl)amino)-2,7-di-tert-butyl-9,9-dimethyl-9H-xanthen-4-yl)imino)methyl)benzene-1,2-diol) features two different chelating positions bridged by a xanthene linker: bis(pyridyl)amine for Cu(I) and catecholate for Mo(VI). LH2 was synthesized via the initial protection of one of the amine positions, followed by two consecutive alkylations of the second position, deprotection, and condensation to attach the catechol functionality. LH2 was found to exhibit dynamic cooperativity between two reactive sites mediated by H-bonding of the catechol protons. In the free ligand, catechol protons exhibit H-bonding with imine (intramolecular) and with pyridine (intermolecular in the solid state). The reaction of LH2 with [Cu(NCMe)4]+ led to the tetradentate coordination of Cu(I) via all nitrogen donors of the ligand, including the imine. Cu(I) complexes were characterized by multinuclear NMR spectroscopy, high-resolution mass spectrometry (HRMS), X-ray crystallography, and DFT calculations. Cu(I) coordination to the imine disrupted H-bonding and caused rotation away from the catechol arm. The reaction of the Cu(I) complex [Cu(LH2)]+ with a variety of monodentate ligands X (PPh3, Cl-, SCN-, CN-) released the metal from coordination to the imine, thereby restoring imine H-bonding with the catechol proton. The second catechol proton engages in H-bonding with Cu-X (X = Cl, CN, SCN), which can be intermolecular (XRD) or intramolecular (DFT). The reaction of LH2 with molybdate [MoO4]2- led to incorporation of [MoVIO3] at the catecholate position, producing [MoO3(L)]2-. Similarly, the reaction of [Cu(LH2)]+ with [MoO4]2- formed the heterodinuclear complex [CuMoO3(L)]-. Both complexes were characterized by multinuclear NMR, UV-vis, and HRMS. HRMS in both cases confirmed the constitution of the complexes, containing molecular ions with the expected isotopic distribution.

Noncovalent interactions in catechol/ammonium-rich adhesive motifs: Reassessing the role of cation-π complexes?

Cation-π interactions between ammonium and catechol groups provide a commonly held paradigm in the complex interplay of noncovalent forces that govern both biological phenomena, such as underwater adhesion in mussel byssus and other marine organisms, and aggregation processes in self-assembly of catecholamine-derived polymers. However, closer consideration of the peculiar properties of the catechol functionality, that features two adjacent phenoxyl groups endowed with chelating properties, would suggest operation of alternate interaction geometries besides typical cation-π. Following previous studies on various alkali metal cations, we report herein compelling computational evidence in favor of a so far overlooked σ-type interaction between the ammonium cation and the catechol system, as the most important contributor to binding, far exceeding the cation-π component. The present findings would hence prompt an experimental and theoretical reassessment of the actual importance of cation-π against σ-type interaction between ammonium and catechol groups in underwater adhesive patterns. In this framework, the catechol-ammonium interaction energy potential surfaces herein reported may provide an improved reference to approach more realistic natural and synthetic adhesion models encompassing other participating molecules/ions and the role of the solvent.

Surface Functionalization of Ti3C2Tx MXene Nanosheets with Catechols: Implication for Colloidal Processing.

Precise tailoring of two-dimensional nanosheets with organic molecules is critical to passivate the surface and control the reactivity, which is essential for a wide range of applications. Herein, we introduce catechols to functionalize exfoliated MXenes (Ti3C2Tx) in a colloidal suspension. Catechols react spontaneously with Ti3C2Tx surfaces, where binding is initiated from a charge-transfer complex as confirmed by density functional theory (DFT) and UV-vis. Ti3C2Tx sheet interlayer spacing is increased by catechol functionalization, as confirmed by X-ray diffraction (XRD), while Raman and atomic force microscopy-infrared spectroscopy (AFM-IR) measurements indicate binding of catechols at the Ti3C2Tx surface occurs through metal-oxygen bonds, which is supported by DFT calculations. Finally, we demonstrate immobilization of a fluorescent dye on the surface of MXene. Our results establish a strategy for tailoring MXene surfaces via aqueous functionalization with catechols, whereby colloidal stability can be modified and further functionality can be introduced, which could provide excellent anchoring points to grow polymer brushes and tune specific properties.

Dispersant Molecules with Functional Catechol Groups for Supercapacitor Fabrication.

Cathodes for supercapacitors with enhanced capacitive performance are prepared using MnO2 as a charge storage material and carbon nanotubes (CNT) as conductive additives. The enhanced capacitive properties are linked to the beneficial effects of catecholate molecules, such as chlorogenic acid and 3,4,5-trihydroxybenzamide, which are used as co-dispersants for MnO2 and CNT. The dispersant interactions with MnO2 and CNT are discussed in relation to the chemical structures of the dispersant molecules and their biomimetic adsorption mechanisms. The dispersant adsorption is a key factor for efficient co-dispersion in ethanol, which facilitated enhanced mixing of the nanostructured components and allowed for improved utilization of charge storage properties of the electrode materials with high active mass of 40 mg cm−2. Structural peculiarities of the dispersant molecules are discussed, which facilitate dispersion and charging. Capacitive properties are analyzed using cyclic voltammetry, chronopotentiometry and impedance spectroscopy. A capacitance of 6.5 F cm−2 is achieved at a low electrical resistance. The advanced capacitive properties of the electrodes are linked to the microstructures of the electrodes prepared in the presence of the dispersants.