Rational design and electrical study of conducting bionanocomposites hydrogel based on chitosan and silver nanoparticles

Green synthesis of silver nanoparticles-capped aminated lignin as a robust active catalyst for dye discoloration

Considering the severity of global environmental issues, biomass-derived products have received significant attention as alternatives to foster sustainability and eco-friendliness. The use of metal nanoparticle catalysts for dye decomposition is emerging as a promising approach for environmentally friendly dye removal. In this study, an aminosilane-modified lignin (AML)/silver nanoparticle (AgNP) composite was fabricated and used as a hydrogenation catalyst. The AgNPs were well dispersed on the AML surface and formed strong bonds within the AML/AgNP complex. AML also served as an effective reducing and capping agent for Ag(I) ions. The AML/AgNPs were found to be an efficient catalyst with excellent dye degradation ability and easy reusability. Biomass-derived lignin can be used as a reducing and capping agent for metals and this complex can be used as a high-value bio-catalyst for wastewater remediation.

Hierarchical Design of Tissue-Mimetic Fibrillar Hydrogel Scaffolds

Most tissues of the human body present hierarchical fibrillar extracellular matrices (ECMs) that have a strong influence over their physicochemical properties and biological behavior. Of great interest is the introduction of this fibrillar structure to hydrogels, particularly due to the water-rich composition, cytocompatibility, and tunable properties of this class of biomaterials. Here, the main bottom-up fabrication strategies for the design and production of hierarchical biomimetic fibrillar hydrogels and their most representative applications in the fields of tissue engineering and regenerative medicine are reviewed. For example, the controlled assembly/arrangement of peptides, polymeric micelles, cellulose nanoparticles (NPs), and magnetically responsive nanostructures, among others, into fibrillar hydrogels is discussed, as well as their potential use as fibrillar-like hydrogels (e.g., those from cellulose NPs) with key biofunctionalities such as electrical conductivity or remote stimulation. Finally, the major remaining barriers to the clinical translation of fibrillar hydrogels and potential future directions of research in this field are discussed.

Biodegradable Conducting Polymer-Based Composites for Biomedical Applications-A Review

In recent years, researchers have increasingly directed their focus toward the biomedical field, driven by the goal of engineering polymer systems that possess a unique combination of both electrical conductivity and biodegradability. This convergence of properties holds significant promise, as it addresses a fundamental requirement for biomedical applications: compatibility with biological environments. These polymer systems are viewed as auspicious biomaterials, precisely because they meet this critical criterion. Beyond their biodegradability, these materials offer a range of advantageous characteristics. Their exceptional processability enables facile fabrication into various forms, and their chemical stability ensures reliability in diverse physiological conditions. Moreover, their low production costs make them economically viable options for large-scale applications. Notably, their intrinsic electrical conductivity further distinguishes them, opening up possibilities for applications that demand such functionality. As the focus of this review, a survey into the use of biodegradable conducting polymers in tissue engineering, biomedical implants, and antibacterial applications is conducted.

Poly (aniline-co-aniline-2,5-disulfonic acid) / L-ascorbic acid / Ag@SiO2 / polysafranin nanocomposite: synthesis, characterization and anomalous electrical behaviour

We report the synthesis of sulfonated copolyaniline/polysafranin/L-ascorbic acid/Ag@SiO2 fine powdered nanocomposites and investigate the influence of incorporating the dye on their conductivity. The composite was characterized via IR, UV, cyclic voltammetry (CV), electric, dielectric, SEM, TEM, TGA and DSC measurements. Microscopy images revealed intensified spherical particles that were dispersed across the entire surface, and the SiO2/Ag particles were distributed on the surface. The XRD results exhibited peaks at many 2q values, and their interatomic spacing (d) and crystallite (grain) sizes were calculated. The thermal degradation curves exhibited an interesting model of stability. The cyclic voltammogram exhibited redox peaks identical to those of the reported analogues. The d.c. conductivity of the oligomer varied from 0.06 - 0.016 (s/cm), and that of the composite varied from 0.008 to 0.016 (s/cm). The material changed from a semiconductor to a metallic material. The observed conductivity is mainly attributed to self-doping between the sulfonate groups and the charged nitrogen atoms in the polymer chains. The frequency dependence of the permittivity, ε', showed a marked effect on the frequency window under consideration. The permittivity, ε', is independent of the increase in the frequency of the oligomer and the composite. This behavior supports the non-Debye dependency by confirming the occurrence of electrode polarization and space charge effects. In conclusion, the incorporation of safranin dye with a thermally stable, highly sulfonated polyaniline derivative/Ag@SO2 nanocomposite achieved improved conductivity after heating. The d.c. conductivities are comparable to those of many commercial inorganic or organic composites, and because of their attractive electrical properties, we suggest that these materials are promising for electronic field applications.

Review of sustainable, eco-friendly, and conductive polymer nanocomposites for electronic and thermal applications: current status and future prospects

Biodegradable polymer nanocomposites (BPNCs) are advanced materials that have gained significant attention over the past 20 years due to their advantages over conventional polymers. BPNCs are eco-friendly, cost-effective, contamination-resistant, and tailorable for specific applications. Nevertheless, their usage is limited due to their unsatisfactory physical and mechanical properties. To improve these properties, nanofillers are incorporated into natural polymer matrices, to enhance mechanical durability, biodegradability, electrical conductivity, dielectric, and thermal properties. Despite the significant advances in the development of BPNCs over the last decades, our understanding of their dielectric, thermal, and electrical conductivity is still far from complete. This review paper aims to provide comprehensive insights into the fundamental principles behind these properties, the main synthesis, and characterization methods, and their functionality and performance. Moreover, the role of nanofillers in strength, permeability, thermal stability, biodegradability, heat transport, and electrical conductivity is discussed. Additionally, the paper explores the applications, challenges, and opportunities of BPNCs for electronic devices, thermal management, and food packaging. Finally, this paper highlights the benefits of BPNCs as biodegradable and biodecomposable functional materials to replace traditional plastics. Finally, the contemporary industrial advances based on an overview of the main stakeholders and recently commercialized products are addressed.

Review on chitosan-based antibacterial hydrogels: Preparation, mechanisms, and applications

Chitosan (CS) is known for its remarkable properties, such as good biocompatibility, biodegradability, and renewability, in addition to its antibacterial and biological activities. However, as CS is insoluble in water, it displays limited antibacterial performance under neutral and physiological conditions. A viable solution to this problem is grafting chemically modified groups onto the CS framework, thereby increasing its solubility and enhancing its antibacterial effect. Herein, the antibacterial action mechanism of CS and its derivatives is reviewed, confirming the prevalent use of composite materials comprising CS and its derivatives as an antibacterial agent. Generally, the antimicrobial ability of CS-based biomaterials can be enhanced by incorporating supplementary polymers and antimicrobial agents. Research on CS-based composite biomaterials is ongoing and numerous types of biomaterials have been reported, including inorganic nanoparticles, antibacterial agents, and CS derivatives. The development of these composite materials has considerably expanded the application of CS-based antibacterial materials. This study reviews the latest progress in research regarding CS-based composite hydrogels for wound repair, tissue engineering, drug release, water purification, and three-dimensional printing applications. Finally, the summary and future outlook of CS-based antibacterial hydrogels are presented in anticipation of a broader range of applications of CS-based antibacterial hydrogels.

Developments and application of chitosan-based adsorbents for wastewater treatments

Water quality is deteriorating continuously as increasing levels of toxic inorganic and organic contaminants mostly discharging into the aquatic environment. Removal of such pollutants from the water system is an emerging research area. During the past few years use of biodegradable and biocompatible natural additives has attracted considerable attention to alleviate pollutants from wastewater. The chitosan and its composites emerged as a promising adsorbents due to their low price, abundance, amino, and hydroxyl groups, as well as their potential to remove various toxins from wastewater. However, a few challenges associated with its practical use include lack of selectivity, low mechanical strength, and solubility in acidic medium. Therefore, several approaches for modification have been explored to improve the physicochemical properties of chitosan for wastewater treatment. Chitosan nanocomposites found effective for the removal of metals, pharmaceuticals, pesticides, microplastics from the wastewaters. Nanoparticle doped with chitosan in the form of nano-biocomposites has recently gained much attention and proven a successful tool for water purification. Hence, applying chitosan-based adsorbents with numerous modifications is a cutting-edge approach to eliminating toxic pollutants from aquatic systems with the global aim of making potable water available worldwide. This review presents an overview of distinct materials and methods for developing novel chitosan-based nanocomposites for wastewater treatment.

Assessment of self-doped poly (5-nitro-2-orthanilic acid) as a scaling inhibitor to control the precipitation of CaCO3 and CaSO4 in solution

Self-doped- and nitro-polyanilines have become a widely used strategy to optimize the electronic and vibratory spectra of polymeric building blocks in various applications. We report the synthesis of poly (5-nitro-2-orthanilic acid) by an aniline-initiated oxidative polymerization reaction. The polymer is characterized by spectroscopic techniques, elemental shapes, cyclic voltammetry, electrical conductivity, and microscopic and thermal measurements. The hydrophilic and hydrophobic nature of the supports provided the formation of amphiphilicity as judged by SEM. Thermogravimetric measurements reveal thermal stability up to 500 °C and glass temperature (T_g) observed at 240 °C. Electrical conductivity decreases as the temperature rises at the different frequencies used, reflecting the semiconducting nature in the extrinsic range, which is characterized by high carriers and low mobility. The presence of these electron residues causes a decrease in efficiency and increases the thermal conductivity. Dielectric measurements have shown that permittivity decreases gradually at lower levels, mainly due to the transport of charging carriers, resulting in higher performance. The testing of the copolymer as a new scale blocker has resulted in moderate to fairly high performance. This effect is attributed to the change in polymer geometry using intramolecular H-bonding group -SO₃H and a chain polymer in an aqueous medium.

Regenerative rehabilitation with conductive biomaterials for spinal cord injury

The individual approaches of regenerative medicine efforts alone and rehabilitation efforts alone have not yet fully restored function after severe spinal cord injury (SCI). Regenerative rehabilitation may be leveraged to promote regeneration of the spinal cord tissue, and promote reorganization of the regenerated neural pathways and intact spinal circuits for better functional recovery for SCI. Conductive biomaterials may be a linchpin that empowers the synergy between regenerative medicine and rehabilitation approaches, as electrical stimulation applied to the spinal cord could facilitate neural reorganization. In this review, we discuss current regenerative medicine approaches in clinical trials and the rehabilitation, or neuromodulation, approaches for SCI, along with their respective translational limitations. Furthermore, we review the translational potential, in a surgical context, of conductive biomaterials (e.g., conductive polymers, carbon-based materials, metallic nanoparticle-based materials) as they pertain to SCI. While pre-formed scaffolds may be difficult to translate to human contusion SCIs, injectable composites that contain blended conductive components and can form within the injury may be more translational. However, given that there are currently no in vivo SCI studies that evaluated conductive materials combined with rehabilitation approaches, we discuss several limitations of conductive biomaterials, including demonstrating safety and efficacy, that will need to be addressed in the future for conductive biomaterials to become SCI therapeutics. Even so, the use of conductive biomaterials creates a synergistic opportunity to merge the fields of regenerative medicine and rehabilitation and redefine what regenerative rehabilitation means for the spinal cord. STATEMENT OF SIGNIFICANCE: For spinal cord injury (SCI), the individual approaches of regenerative medicine and rehabilitation are insufficient to fully restore functional recovery; however, the goal of regenerative rehabilitation is to combine these two disparate fields to maximize the functional outcomes. Concepts similar to regenerative rehabilitation for SCI have been discussed in several reviews, but for the first time, this review considers how conductive biomaterials may synergize the two approaches. We cover current regenerative medicine and rehabilitation approaches for SCI, and the translational advantages and disadvantages, in a surgical context, of conductive biomaterials used in biomedical applications that may be additionally applied to SCI. Furthermore, we identify the current limitations and translational challenges for conductive biomaterials before they may become therapeutics for SCI.

Gelatin-based adhesive hydrogel with self-healing, hemostasis, and electrical conductivity

As a kind of natural protein derived material, gelatin has been widely used in the preparation of medical hydrogels due to its good biocompatibility, non-immunogenicity and the ability of promoting cell adhesion. Functionalization of gelatin-based hydrogels is a hot topic in research and its clinic application. Herein, a novel gelatin-based adhesive hydrogel was prepared via mussel-inspired chemistry. Gelatin was firstly functionalized by dopamine to form dopamine grafted gelatin (GelDA). After the mixture with 1,4-phenylenebisboronic acid and graphene oxide (GO), the GelDA/GO hydrogels were obtained by H₂O₂/HRP (horseradish peroxidase) catalytic system. Based on the self-healing and tissue adhesion of the hydrogels, the hemostatic property has been exhibited in the rat hepatic hemorrhage model. Additionally, the incorporation of GO endowed conductivity and enhanced the mechanical property of GelDA/GO hydrogels. The electromyography (EMG) signals of finger movement were successfully monitored by using hydrogel as the adhesive electrodes of EMG monitor. L929 cell experiments showed that the hydrogels had good cytocompatibility. The results indicated the potential application of GelDA/GO hydrogels in tissue adhesives, wound dressings, and wearable devices.

Preparation of conductive cellulose fabrics with durable antibacterial properties and their application in wearable electrodes

Electroless silver plating on fabrics can obtain conductive and antibacterial bifunctional materials which can be used as electrodes in wearable electronic products. However, these activities are deteriorated easily after washing because of the falling off of silver coating resulted from the weak adhesion. In order to improve the binding force between silver and cellulose fabrics, 3-mercaptopropytrimethoxysilane (MPTS) was applied to modify cellulose fabrics before silver electroless plating to develop the durable conductive fabrics with excellent antibacterial. The silver nanoparticles (Ag NPs) deposition process was observed via field emission scanning electron microscopy (FESEM), thermal properties were evaluated by thermogravimetric analysis (TGA). A dense and uniform silver layer was formed on the fabric. The initial electrical resistance of the conductive fabric was 0.04 Ω/sq and lowered than 2 Ω/sq after 200 washing cycles. The antibacterial efficiency of the fabric after 200 washing cycles remained 92.82%, compared to 100% with the fabric before washing. Moreover, the inhibition rate was determined by optical density of bacteria suspension at 260 nm and further substantiated by releasing of Ag⁺ from the fabric. The conductive fabrics were applied as wearable electrodes to capture electrocardiogram (ECG) signals of human in static states and running states.

Applications of nanotechnology on vegetable crops

Agriculture is the backbone of most developing countries, and most of their people depend on it for their livelihood. The world population is increased by approximately 83 million people each year, so there is a need to increase agricultural productivity. At present, productivity growth can be achieved either by expanding the area cultivated or increasing crop yields through improving the efficiency of fertilizers used. Therefore, there has been a trend to use modern technologies, such as nanotechnology (NT), to increase the productivity of plants. Where, it is involved in the food production process, from planting to packaging. NT improves plants' ability to absorb nutrients, and the agronomic properties of soil, which improves plant growth and productivity. Economically, NT increased the efficiency of nano-fertilizers, and so contributed to increasing productivity and the production of crops. However, the study of the effect of nanotechnology on the environment of soils and plants did not receive the required study. In this review, a comprehensive survey is exhibited on NT as an effective method in dealing with the problem of fertilizer loss during irrigation. This review discusses the technologies and applications of the latest research findings in this field. Furthermore, this review deals with the forms and types of nanoparticles and the methods of their transmission in plants, as well as their effect on plants (physiological and DNA) as well as on those who eat those plants.

Development of polymer composites and encapsulation technology for slow-release fertilizers

The fertilizer manufacturing faces an ongoing challenge to develop its products to raise the effectiveness of their application, mainly of nitrogenous fertilizers, as well as to reduce any probable adverse ecological effect. In general, chemical fertilizers are very necessary for agricultural lands to provide the essential nutrients for plant growth, which are lost and leached into the surrounding environment during irrigation, which then leads to unwanted side effects, such as crop failure or increased losses to the environment. To solve this problem of nutrients being wasted, the most effective way is to use slow or controlled-release fertilizers (S/CRFs). The current review provides an insight vision into the methods used to save agricultural fertilizers from being wasted due to irrigation. The functional materials or physical techniques are used to maintain a steady release of nutrients. Fertilizers are encapsulated with various compounds based on synthetic or natural polymers to be used as SRFs. In this review paper, a comprehensive survey is presented on SRFs as an effective method in dealing with the problem of fertilizer wastage during irrigation. This review discusses the technology and applications of the latest research findings in this field.

Engineering next-generation bioinks with nanoparticles: moving from reinforcement fillers to multifunctional nanoelements

The application of additive manufacturing in the biomedical field has become a hot topic in the last decade owing to its potential to provide personalized solutions for patients. Different bioinks have been designed trying to obtain a unique concoction that addresses all the needs for tissue engineering and drug delivery purposes, among others. Despite the remarkable progress made, the development of suitable bioinks which combine printability, cytocompatibility, and biofunctionality is still a challenge. In this sense, the well-established synthetic and functionalization routes to prepare nanoparticles with different functionalities make them excellent candidates to be combined with polymeric systems in order to generate suitable multi-functional bioinks. In this review, we briefly discuss the most recent advances in the design of functional nanocomposite hydrogels considering their already evaluated or potential use as bioinks. The scientific development over the last few years is reviewed, focusing the discussion on the wide range of functionalities that can be incorporated into 3D bioprinted constructs through the addition of multifunctional nanoparticles in order to increase their regenerative potential in the field of tissue engineering.

Conducting chitosan/hydroxylethyl cellulose/polyaniline bionanocomposites hydrogel based on graphene oxide doped with Ag-NPs

The current work focuses on a cheap and simple preparation of highly conducting chitosan/hydroxyl ethylcellulose/polyaniline loaded with graphene oxide doped by silver nanoparticles (CS/HEC/PAni/GO@Ag) bionanocomposite as a biodegradable and biocompatible hydrogel for energy storage technology. Scanning electron microscopy (SEM) displays the compatibility of chitosan, hydroxyl ethyl cellulose, and polyaniline and a good distribution of GO@Ag-NPs in bionanocomposite hydrogels. X-ray diffraction (XRD) displayed the structure and existence of GO@Ag-NPs in the matrix. The swelling percentage and the antibacterial activities slightly increased with raising the content of GO@Ag-NPs. Also, the presence of both chitosan and cellulose improves the biodegradation of the fabricated bionanocomposites, which is increased by adding GO. Moreover, the incorporation of 5% GO@Ag-NPs in hydrogels enhances dc-conductivity by about 25 times from 3.37 × 10^-3 to 8.53 × 10^-2 S/cm. The fabricated hydrogels are inexpensive, eco-friendly, and have high capacitance and permittivity, and so they can store electrical energy.

In situ synthesis of Fe3O4@ cyanoethyl cellulose composite as antimicrobial and semiconducting film

Cyanoethyl cellulose (CEC)/ magnetite (Fe₃O₄) flexible composite film with enhanced dielectric and magnetic properties was successfully prepared. CEC has been synthesized from micro crystalline cellulose (MCC). The effects of magnetite mass fraction on the morphology, microstructure, thermal stability, and antimicrobial activity of the as-prepared composite films were investigated. The Vibrating sample magnetometer (VSM) and broadband dielectric spectrometer was also employed to study the magnetic and dielectric properties, respectively. In addition to study the computational calculation of MCC, and CEC by DFT/ B3LYP/6-31G (d) basis sets. The results showed that, the sample that is magnetite free has a diamagnetic response to the applied magnetic field, however the other samples that is loaded with magnetite show super-paramagnetic behavior indicating that the particles' sizes of the magnetite mostly below 20 nm. Also, antimicrobial activities of composite films against (G + ve), (G-ve), were investigated.