Preparation of carboxymethyl cellulose/polyvinyl alcohol wound dressing composite immobilized with anthocyanin extract for colorimetric monitoring of wound healing and prevention of wound infection

Optically pH-Sensing in smart wound dressings towards real-time monitoring of wound states: A review

BACKGROUND

Over the recent years, the investigations on wound dressings have been undergoing significant evolution, and now smart dressings with the function of the real-time monitoring of the wound states have been recognized as one of the most advanced treatment modalities. Among a variety of wound-related biomarkers, pH represents a promising candidate for in situ supervising the wound healing status. In this regard, a variety of optically pH sensing agents have been widely incorporated into different types of wound dressings.

RESULTS

Herein, we first presented an overview of the advanced wound dressings, especially those commonly used in wound pH sensing. Then, a comprehensive summary of the optical pH sensing agents that could be incorporated into the wound dressings for detecting the pH alteration on the wound bed was described in detail. These materials were classified into colorimetric dyes (i.e., synthetic and plant-based dyes) and fluorescent probes (i.e., small-molecular fluorescein and fluorescent nanomaterials). Each type of pH sensing agent was fully discussed with advantages and limitations for monitoring the wound pH alteration, as well as typical examples of practical applications. To well interpret messages produced by the color-coding dressings, the approaches for defining and communicating color were also summarized, and a proof-of-concept, the smartphone-based remote supervision was particularly highlighted.

SIGNIFICANCE

This review provides a comprehensive overview of the utilization of optically pH sensing in advanced wound dressings for the real-time monitoring of the wound states. It was expected to be an informative source for the exploitation of novel diagnostic dressings for wound management, and also a reference the for application of these materials in the biosensing of other physiological or pathological fluids.

Polyphenols in wound healing: unlocking prospects with clinical applications

Wound healing is a multifaceted, complex process that factors like aging, metabolic diseases, and infections may influence. The potentiality of polyphenols, natural compounds, has shown anti-inflammatory and antimicrobial properties in promoting wound healing and their potential applications in wound management. The studies reviewed indicate that polyphenols have multiple mechanisms that promote wound healing. This involves enhancing antioxidant defenses, reducing oxidative stress, modulating inflammatory responses, improving healing times, reducing infection rates, and enhancing tissue regeneration in clinical trials and in vivo and in vitro studies. Polyphenols have been proven to be effective in managing hard-to-heal wounds, especially in diabetic and elderly populations. Polyphenols have shown significant benefits in promoting angiogenesis and stimulating collagen synthesis. Polyphenol treatment has been demonstrated to have therapeutic effects in wound healing and chronic wound management. Their ability to regulate key healing processes makes them suitable for new wound care products and treatments. Future research should enhance formulations and delivery methods to optimize polyphenols' bioavailability and therapeutic efficacy in wound management approaches.

Characterization and antibacterial activity of cellulose extracted from Washingtonia robusta and Phoenix dactylifera L. impregnated with eugenol: Promising wound dressing

This paper aimed to valorize two varieties of date palm mesh, Washingtonia robusta (S1) and Phoenix Dactylifera L. (S2) by extracting their fibrous cellulose structures for potential application in wound dressings. The extracted fibrous dressings were analyzed by using Fourier Transforms Infrareded (FTIR), X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). Additionally, mechanical properties, water absorption, and antimicrobial activity were analyzed. The results showed that S2 contained significantly higher fiber content (37.21 %) compared to S1 (12.63 %). FTIR analysis confirmed successful cellulose extraction from both palm varieties. SEM images showed that S1 fibers had a smooth-surface with smaller pores, contributing to a higher absorption capacity of 1289 ± 93 %. Therefore, S2 exhibited rougher-surfaced fibers, which enhanced its mechanical properties, as demonstrated by stress-strain tensile tests, and Young's modulus. Notably, S2 revealed superior mechanical strength compared to S1 fiber dressings. Water absorption for S2 was calculated at 509 ± 93 %. Both S1 and S2 exhibited high crystalline index (61.17 % and 62.88 %), with crystalline size of 3.54 nm for S1 and 10.03 nm for S2. Finally, Eugenol-enriched fibers showed significant activity against E. coli (3.8 mm and 2.3 mm), S. aureus (4.00 mm and 2.05 mm), and S. epidermidis (2.7 mm and 1.6 mm) for S1 and S2, respectively, suggesting their potential as effective new wound dressing materials.

Recent advances of bioaerogels in medicine: Preparation, property and application

Bioaerogels represent a type of three-dimensional porous materials fabricated from natural biopolymers, and show a significant potential for medical application due to their characteristics of extremely low density, high specific surface area, excellent biocompatibility and biodegradability. The preparation method and parameters of bioaerogels are focused on, and their influence on the structure and properties of bioaerogels are discussed in detail. Then, to match the properties of bioaerogels with the medical applications, this work emphasizes the main properties (including biocompatibility, degradability, and mechanical properties), structural parameters (such as suitable porosity, pore size and high specific surface area), and further summarizes the influence of single-component and composite bioaerogels on their properties. Moreover, according to the different applications (wound healing, drug delivery, and tissue engineering and other fields), the function method, mechanism and practical effect of bioaerogels are comprehensively analyzed. Finally, the challenges, future research directions, and solutions for the practical application of bioaerogels in medicine are discussed.

Foam-based antibacterial hydrogel composed of carboxymethyl cellulose/polyvinyl alcohol/cerium oxide nanoparticles for potential wound dressing

Foam-based wound dressing materials produced by dispersing gas phases in a polymeric material are soft, adapt to the body shape, and allow the absorption of wound exudate due to their porous structure. Most of these formulations are based on synthetic substances such as polyurethane. However, biopolymers have entered the field as a new player thanks to their biocompatible and sustainable nature. Incorporating biopolymers in formulations is gaining interest in scientific literature, and we extend this approach by adding antibacterial cerium oxide nanoparticles to biopolymer formulation. We introduce a novel biopolymer composite of carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and cerium oxide nanoparticles (CeO2 NPs), namely PVA-CMC@CeO2. This mixture was first foamed and then cross-linked with sodium tetraborate solution, followed by a freeze-thaw process. After the novel material's spectroscopic, structural, and morphological characterization, we investigated its swelling, drug-delivery, antibacterial, and biodegradability properties PVA-CMC@CeO2 dressing effectively inhibits Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) growth and delivers the antibiotic drug silver sulfadiazine for up to 6 h. The antibacterial properties, good swelling, and drug release profile of the blend material show promising potential in wound care applications.

Recent advances in bioactive wound dressings

Traditional wound dressings, despite their widespread use, face limitations, such as poor infection control and insufficient healing promotion. To address these challenges, bioactive materials have emerged as a promising solution in wound care. This comprehensive review explores the latest developments in wound healing technologies, starting with an overview of the importance of effective wound management, emphasising the need for advanced bioactive wound dressings. The review further explores various bioactive materials, defining their characteristics. It covers a wide range of natural and synthetic biopolymers used to develop bioactive wound dressings. Next, the paper discusses the incorporation of bioactive agents into wound dressings, including antimicrobial and anti-inflammatory agents, alongside regenerative components like growth factors, platelet-rich plasma, platelet-rich fibrin and stem cells. The review also covers fabrication techniques for bioactive wound dressings, highlighting techniques like electrospinning, which facilitated the production of nanofibre-based dressings with controlled porosity, the sol-gel method for developing bioactive glass-based dressings, and 3D bioprinting for customised, patient-specific dressings. The review concludes by addressing the challenges and future perspectives in bioactive wound dressing development. It includes regulatory considerations, clinical efficacy, patient care protocol integration and wound healing progress monitoring. Furthermore, the review considers emerging trends such as smart materials, sensors and personalised medicine approaches, offering insights into the future direction of bioactive wound dressing research.

Zn@TA assisted dual cross-linked 3D printable glycol grafted chitosan hydrogels for robust antibiofilm and wound healing

Rapid regeneration of the injured tissue or organs is necessary to achieve the usual functionalities of the damaged parts. However, bacterial infections delay the regeneration process, a severe challenge in the personalized healthcare sector. To overcome these challenges, 3D-printable multifunctional hydrogels of Zn/tannic acid-reinforced glycol functionalized chitosan for rapid wound healing were developed. Polyphenol strengthened intermolecular connections, while glutaraldehyde stabilized 3D-printed structures. The hydrogel exhibited enhanced viscoelasticity (G'; 1.96 × 104 Pa) and adhesiveness (210 kPa). The dual-crosslinked scaffolds showed remarkable antibacterial activity against Bacillus subtilis (∼81 %) and Escherichia coli (92.75 %). The hydrogels showed no adverse effects on human dermal fibroblasts (HDFs) and macrophages (RAW 264.7), indicating their superior biocompatibility. The Zn/TA-reinforced hydrogels accelerate M2 polarization of macrophages through the activation of anti-inflammatory transcription factors (Arg-1, VEGF, CD163, and IL-10), suggesting better immunomodulatory effects, which is favorable for rapid wound regeneration. Higher collagen deposition and rapid re-epithelialization occurred in scaffold-treated rat groups vis-à-vis controls, demonstrating superior wound healing. Taken together, the developed multifunctional hydrogels have great potential for rapidly regenerating bacteria-infected wounds in the personalized healthcare sector.

Integration of Functional Polymers and Biosensors to Enhance Wound Healing

Biosensors have led to breakthroughs in the treatment of chronic wounds. Since the discovery of the oxygen electrode by Clarke, biosensors have evolved into the design of smart bandages that dispense drugs to treat wounds in response to physiological factors, such as pH or glucose concentration, which indicate pathogenic tendencies. Aptamer-based biosensors have helped identify and characterize pathogenic bacteria in wounds that often form antibiotic-resistant biofilms. Several functional polymers have served as indispensable parts of the fabrication of these biosensors. Beginning with natural polymers such as alginate, chitosan, and silk-based fibroin, which are biodegradable and absorptive, advances have been made in formulating biocompatible synthetic polymers such as polyurethane and polyethylene glycol designed to reduce non-specific binding of proteins and cells, making biosensors less painful or cumbersome for patient use. Recently, polycaprolactone has been developed, which offers ductility and a large surface-area-to-volume ratio. There is still room for advances in the fabrication and use of biosensors for wound healing and in this review, the trend in developing biosensors from biomarker detection to smart dressings to the incorporation of machine learning in designing customized wound patches while making application easier is highlighted and can be used for a long time.

Optimized production of carboxymethyl cellulose/guar gum based durable hydrogel for in vitro performance assessment

An important objective of researchers is to develop a perfect wound dressing that can effectively treat different kinds of wounds. Natural substances with beneficial qualities, such as plant extracts and biopolymers are an ideal aid for wound care. Hydrogels based on biopolymers offer a lot of promising applications for topical use and are biocompatible, hydrophilic and non-toxic. When employed alone or in conjunction with other active agents, herbal extracts have a great deal of use in the healing of wounds. This study comprises Ruellia tuberosa extract loaded with carboxymethyl cellulose and guar gum hydrogels that have potential anti-bacterial, antioxidant, anti-inflammatory and hemocompatibility. Using mouse fibroblast cells (L929), the MTT (3- (4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) test was conducted to assess the biocompatibility. Furthermore, the scratch wound assay using the L929 fibroblast cell line of mouse was employed to assess the in vitro wound healing potential of the synthesised composite hydrogels.

Synergistic berberine chloride and Curcumin-Loaded nanofiber therapies against Methicillin-Resistant Staphylococcus aureus Infection: Augmented immune and inflammatory responses in zebrafish wound healing

BACKGROUND

Wound healing pivots on a finely orchestrated inflammatory cascade, critical for tissue repair. Chronic wounds, compounded by persistent inflammation and susceptibility to infection, pose formidable clinical challenges. Nanofiber dressings offer promising avenues for wound care, yet their interaction with inflammation and infection remains elusive. We aim to delineate the inflammatory cascade preceding wound closure and assess Cu@Bbc nanofibers' therapeutic efficacy in mitigating inflammation and combating infection. Their unique attributes suggest promise in modulating inflammation, fostering tissue regeneration, and preventing microbial colonization. Investigating the intricate interplay between nanofiber scaffolds, inflammation, and infection may unveil mechanisms of enhanced wound healing. Our findings could stimulate the development of tailored dressings, urgently needed for effective wound management amidst immune dysregulation, infection, and inflammation.

METHODS

In this investigation, we synthesized Cu@Bbc nanofibers, incorporating curcumin and berberine chloride, for wound healing applications. We evaluated their individual and combined antibacterial, anti-biofilm, and antioxidant activities, alongside binding affinity with pro-inflammatory cytokines through molecular docking. Morphological characterization was conducted via SEM, FTIR assessed functional groups, and wettability contact angle measured hydrophobic properties. The physical properties, including tensile strength, swelling behavior, and thermal stability, were evaluated using tensile testing, saline immersion method and thermogravimetric analysis. Biodegradability of the nanofibers was assessed through a soil burial test. Biocompatibility was determined via MTT assay, while wound healing efficacy was assessed with in vitro scratch assays. Controlled drug release and antibacterial activity against MRSA were examined, with in vivo assessment in a zebrafish model elucidating inflammatory responses and tissue remodeling.

RESULTS

In this study, the synergistic action of curcumin and berberine chloride exhibited potent antibacterial efficacy against MRSA, with significant anti-mature biofilm disruption. Additionally, the combination demonstrated heightened antioxidant potential. Molecular docking studies revealed strong binding affinity with pro-inflammatory cytokines, suggesting a role in expediting the inflammatory response crucial for wound healing. Morphological analysis confirmed nanofiber quality, with drug presence verified via FTIR spectroscopy. Cu@Bbc demonstrated higher tensile strength, optimal swelling behavior, and robust thermal stability as evaluated through tensile testing and thermogravimetric analysis. Additionally, the Cu@Bbc nanofiber showed enhanced biodegradability, as confirmed by the soil burial test. Biocompatibility assessments showed favorable compatibility, while in vitro studies demonstrated potent antibacterial activity. In vivo zebrafish experiments revealed accelerated wound closure, re-epithelialization, and heightened immune response, indicative of enhanced wound healing.

CONCLUSION

In summary, our investigation highlights the efficacy of Cu@Bbc nanofibers, laden with curcumin and berberine chloride, in displaying robust antibacterial and antioxidant attributes while also modulating immune responses and inflammatory cascades essential for wound healing. These results signify their potential as multifaceted wound dressings for clinical implementation.

Influence of copper ion cross-linked CMC-PVA film on cell viability and cell proliferation study

In this study, films composed of carboxymethyl cellulose and polyvinyl alcohol were fabricated using the solution casting method. Citric acid (4 %) was employed as a cross-linking agent, while glycerol (3 %) as a plasticizer. Cupric chloride (CuCl2·2H2O) was used for cross-linking at concentrations 0.5 %, 1 %, and 3 % over different times. The cross-linking with copper ions led to a noticeable reduction in elasticity, with the breaking strain ranging from 17.9 %-52.9 %, and increased the contact angle. The ion hydration phenomenon increased the swelling ratio of the films. Fourier-transform infrared (FTIR) spectroscopy confirmed the esterification reactions and copper ion cross-linking with sodium carboxymethyl cellulose (Na-CMC). The films showed antibacterial activity against Staphylococcus aureus and Escherichia coli. The ion-released mechanism followed was the non-Fickian super case-II type. The concentration and duration of cross-linking significantly influenced the cell viability and proliferation. FE-SEM analysis revealed that effective concentrations of CuCl2.2H2O were 0.5 % and 1 %, and the cross-linking times were 5-15 min, facilitating cell attachment and proliferation. Films are non-adhesive with water vapor permeation 800-900 g/m2/day. These results indicate the potential use of the films in treating second-degree burn wounds with low to medium exudate levels. This study provides valuable insights into the development of copper-infused materials for advanced wound healing applications.

Greener healing: sustainable nanotechnology for advanced wound care

Wound healing involves a carefully regulated sequence of events, encompassing pro-inflammatory and anti-inflammatory stages, tissue regeneration, and remodeling. However, in individuals with diabetes, this process gets disrupted due to dysregulation caused by elevated glucose levels and pro-inflammatory cytokines in the bloodstream. Consequently, the pro-inflammatory stage is prolonged, while the anti-inflammatory phase is delayed, leading to impaired tissue regeneration and remodeling with extended healing time. Furthermore, the increased glucose levels in open wounds create an environment conducive to microbial growth and tissue sepsis, which can escalate to the point of limb amputation. Managing diabetic wounds requires meticulous care and monitoring due to the lack of widely available preventative and therapeutic measures. Existing clinical interventions have limitations, such as slow recovery rates, high costs, and inefficient drug delivery methods. Therefore, exploring alternative avenues to develop effective wound-healing treatments is essential. Nature offers a vast array of resources in the form of secondary metabolites, notably polyphenols, known for their antimicrobial, anti-inflammatory, antioxidant, glucose-regulating, and cell growth-promoting properties. Additionally, nanoparticles synthesized through environmentally friendly methods hold promise for wound healing applications in diabetic and non-diabetic conditions. This review provides a comprehensive discussion and summary of the potential wound-healing abilities of specific natural polyphenols and their nanoparticles. It explores the mechanisms of action underlying their efficacy and presents effective formulations for promoting wound-healing activity.

VOLKSMED Database: A Source for Forgotten Wound Healing Plants in Austrian Folk Medicine

The global increase in the incidence of wounds is concerning and fuels the search for new treatment options. The use of traditional medicinal plants in wound healing represents an appreciated available therapeutic possibility. This work introduces the VOLKSMED database, which contains plants and other materials used in Austrian folk medicine, either as monographs or mixtures. This work focuses on the monographs of the database. Concerning wound healing, Hypericum sp., Arnica montana, Calendula officinalis, Plantago sp., and Malva sp. are the most commonly used plants. The focus of this paper is set on selected lesser-known plants (Abies alba, Anthyllis vulneraria, Brassica sp., Gentiana sp., Larix decidua, Picea abies, Sambucus sp., Sanicula europaea) and their status quo in literature concerning wound healing. A systematic search using the databases SciFinder, SCOPUS, and PubMed yielded substantial evidence for the wound healing potential of Brassica sp., Gentiana sp., the Pinaceae A. abies, L. decidua, and P. abies, as well as Sambucus nigra. In vivo and clinical studies substantiate their use in Austrian folk medicine. According to the literature, especially A. vulneraria, Sambucus racemosa, and S. europaea would be worth investigating in-depth since data concerning their wound healing effects - even though scarce - are convincing. In conclusion, the VOLKSMED database contains promising opportunities for further treatment options in the field of wound healing. Future research should consider the listed plants to support their traditional use in Austrian folk medicine and possibly promote the implementation of old knowledge in modern medicine.

Fibrous Structures: An Overview of Their Responsiveness to External Stimuli towards Intended Application

In recent decades, the interest in responsive fibrous structures has surged, propelling them into diverse applications: from wearable textiles that adapt to their surroundings, to filtration membranes dynamically altering selectivity, these structures showcase remarkable versatility. Various stimuli, including temperature, light, pH, electricity, and chemical compounds, can serve as triggers to unleash physical or chemical changes in response. Processing methodologies such as weaving or knitting using responsive yarns, electrospinning, as well as coating procedures, enable the integration of responsive materials into fibrous structures. They can respond to these stimuli, and comprise shape memory materials, temperature-responsive polymers, chromic materials, phase change materials, photothermal materials, among others. The resulting effects can manifest in a variety of ways, from pore adjustments and altered permeability to shape changing, color changing, and thermal regulation. This review aims to explore the realm of fibrous structures, delving into their responsiveness to external stimuli, with a focus on temperature, light, and pH.

An enzyme-responsive hydrogel of ferrocene-grafted carboxymethyl chitosan as a soft electrochemical sensor for MMP-9 detection

Matrix metalloproteinase 9 (MMP-9) plays an important role in wound healing. However, overexpression of MMP-9 leads to the degradation of the newly formed extracellular matrix, which delays wound healing, ultimately leading to chronic wounds. Therefore, timely monitoring of the MMP-9 activity using simple, cost-effective methods is important to prevent the formation of chronic wounds. In this work, ferrocene-modified MMP-9 cleavage peptide (Fc-MG) modified carboxymethyl chitosan hydrogels were prepared as electrochemical biosensors. In the presence of MMP-9, the peptide chain is sheared, and the electrochemically active ferrocene segment is released. Therefore, analyzing the electrochemical activity of hydrogels using differential pulse voltammetry (DPV) can be used to determine MMP-9 activity. The results showed that the DPV peaks were correlated with the MMP-9 concentration in phosphate-buffered saline (PBS, pH 7.4) and Dulbecco's modified Eagle's medium (DMEM). Specifically, the corresponding coefficient of determination (R2) were 0.918 and 0.993. The limit of detections were 73.08 ng/mL and 131.71 ng/mL, respectively. Compared with the enzyme-linked immunosorbent assay, the hydrogel biosensor determined the concentration of MMP-9 in solution with simpler steps. This study demonstrates a novel strategy based on Fc-MG-modified hydrogels to monitor MMP-9 activity in cell secretion samples and shows the potential application in chronic wounds.

Dietary Sources, Stabilization, Health Benefits, and Industrial Application of Anthocyanins-A Review

Natural phytochemicals are well known to protect against numerous metabolic disorders. Anthocyanins are vacuolar pigments belonging to the parent class of flavonoids. They are well known for their potent antioxidant and gut microbiome-modulating properties, primarily responsible for minimizing the risk of cardiovascular diseases, diabetes, obesity, neurodegenerative diseases, cancer, and several other diseases associated with metabolic syndromes. Berries are the primary source of anthocyanin in the diet. The color and stability of anthocyanins are substantially influenced by external environmental conditions, constraining their applications in foods. Furthermore, the significantly low bioavailability of anthocyanins greatly diminishes the extent of the actual health benefits linked to these bioactive compounds. Multiple strategies have been successfully developed and utilized to enhance the stability and bioavailability of anthocyanins. This review provides a comprehensive view of the recent advancements in chemistry, biosynthesis, dietary sources, stabilization, bioavailability, industrial applications, and health benefits of anthocyanins. Finally, we summarize the prospects and challenges of applications of anthocyanin in foods.

Pyrene and Eu3+ modified mesoporous silica used as a fluorescent probe for ratiometric detection of tetracycline antibiotics

The detection of residual tetracycline antibiotics (TCs) in the aquatic environment is important because of the irreversible damage of TCs to the ecosystem and human health. Considering the photostability, sensitivity, and accuracy of the detection systems, mesoporous SBA-15 silica material was an ideal support matrix for improving photostability because it can protect the optical properties of fluorescent signals. To achieve ratiometric detection (with sensitivity and accuracy), pyrene and Eu3+ as two fluorescent signals were implemented into SBA-15, and an organic-inorganic hybrid fluorescent nanoprobe Py/EDTA-SBA-15@Eu3+ was constructed. In the presence of TCs, the red emission of Eu3+ in the nanoprobe was sensitized, and the fluorescence resonance energy transfer occurred from pyrene to Eu3+, resulting in the increased emission of Eu3+ at 617 nm and the decreased emission of pyrene at 384 nm. By monitoring the fluorescent intensity changes at 617 and 384 nm (F617/F384), the nanoprobe achieved the ratiometric detection of oxytetracycline (OTC) and tetracycline (TC) in the range of 0.20-80 and 0.40-80 μM, respectively, with detection limits of 0.18 nM for OTC and 5.83 nM for TC. In addition, the practical application of the nanoprobe was validated in tap water and honey samples.

Preparation of Self-Healing Anthocyanidin-Containing Thermochromic Alginate Ink for Authentication Purposes

Thermochromic inks have proven to be a promising security encoding approach for making commercially available products less susceptible to forgery. However, thermochromic inks have been plagued with poor durability. Thus, self-healable hydrogels can be used as self-repair inks with better durability. Herein, we combined hybrid cellulose nanofibers (CNFs) and sodium alginate (SA) with anthocyanidin(Cy)-based Brassica oleracea L. var. capitata extract in the existence of mordant (ferrous sulfate) to create a self-healing ink for authentication. CNFs were used as a reinforcement agent to enhance the mechanical strength of the sodium alginate hydrogel. Both durability and thermal stability were ensured using self-healing inks. Red cabbage was used to extract Cy-based chromophore as an environmentally friendly spectroscopic probe for immobilization into SA. Using varying concentrations of anthocyanidin, self-healable composite hydrogels (Cy@SA) with thermochromic properties were provided. Using the CIE Lab color coordinate system, homogeneous purple (569 nm) films were printed onto a sheet surface. Upon heating from 25 to 70 °C, the purple color changed to red (433 nm). Transmission electron microscopy was applied to study anthocyanidin/mordant (Cy/M) nanoparticles (NPs). The properties of the applied prints were analyzed using several methods. Both the hydrogel and stamped sheets were tested for their mechanical and rheological characteristics, respectively. Research on the nanocomposite ink (Cy@SA) antibacterial properties and cytotoxicity was also conducted.

Anthocyanin-Loaded Polymers as Promising Nature-Based, Responsive, and Bioactive Materials

Anthocyanins are a specific group of molecules found in nature that have recently received increasing attention due to their interesting biological and colorimetric properties that have been successfully applied in several fields such as food preservation and biomedicine. Consequently, reviews devoted to a general overview of these flavonoids have proliferated in recent years. Meanwhile, the incorporation of anthocyanins into polymeric systems has become an interesting strategy to widen the applicability of these molecules and develop new smart and functional polymers in the above cited areas. However, anthocyanin-based polymers have been scarcely reviewed in the literature. Accordingly, this review aims to be a systematic summary of the most recent approaches for the incorporation of anthocyanins into macro-, micro-, or nanostructured polymers. Moreover, this work describes the fundamentals of the applicability of smart anthocyanin-based polymers and offers an updated review of their most interesting applications as sensors, biological regulators, and active materials.

A fluorescence spectroscopic study of light transmission and adaxial-abaxial distribution of emitting compounds in leaves of Christmas star (Euphorbia pulcherrima)

In situ fluorescence measurements have been used to investigate relative amounts of blue-green pigments and their distributions in plant leaves from Euphorbia pulcherrima. Advantage was taken from the fact that this species has white leaves on the top, with low pigment concentrations, and green leaves on the stem with ordinary pigment concentrations. Excitation- and emission spectra below 410 nm from white leaves, where pigment absorption is low, are not distorted by self-absorption. Absorption- and reflection spectra from white and green leaves were measured using a spectrophotometer equipped with an integrating sphere. The absorption spectra were used to correct recorded fluorescence spectra for self-absorption. Self-absorption corrected photosystem fluorescence from green leaves, modeling light transmission in leaf tissue exponentially, matches to the excitation/emission spectra from white leaves, apart from small differences due to the pigment concentrations and selective scattering. The introduced exponentially decaying transmission relation also predicts that the ratio of excitation spectra from a white and green leaf is in proportion to the absorption spectrum of the green leaf, which was validated for Photosystem II particle fluorescence. This relation was also used to find a scaled absorption spectrum responsible for blue-green emission, which was assumed to originate from lignin. Excitation/emission spectra of the blue-green fluorescence were decomposed into five components and their relative amounts from adaxial and abaxial sides of the leaves have been quantified. Fluorescence lifetime measurements of the leaves, upon 403 nm excitation, revealed three decay times corresponding to the lignin fluorophores emitting in blue and green spectral region, and indicated that emissions at 500 and 550 nm may originate from the same fluorophore residing in the two physically different environments.

Multifunction E-Skin Based on MXene-PA-Hydrogel for Human Behavior Monitoring

Hydrogels have attracted significant attention in various fields, such as smart sensing, human-machine interaction, and biomedicines, due to their excellent flexibility and versatility. However, current hydrogel electronic skins are still limited in stretchability, and their sensing functionality is often single-purpose, making it difficult to meet the requirements of complex environments and multitasking. In this study, we developed an MXene nanoplatelet and phytic acid-coreinforced poly(vinyl alcohol) (PVA) composite, denoted as MXene-PA-PVA. The strong hydrogen bonds formed by the interaction of the different components and the enhancement of chain entanglement result in a significant improvement in the mechanical properties of the PVA/PA/MXene composite hydrogel. This improvement is reflected in an increase of 271.43% in the maximum tensile strain and 35.29% in the maximum fracture stress. Moreover, the composite hydrogel exhibits excellent adhesion, water retention, heat resistance, and conductivity properties. The PVA/PA composite material combined with MXene demonstrates great potential for use as multifunctional sensors for strain and temperature detection with a strain-sensing sensitivity of 3.23 and a resistance temperature coefficient of 8.67. By leveraging the multifunctional characteristics of this composite hydrogel, electronic skin can accurately monitor human behavior and physiological reactions. This advancement opens up new possibilities for flexible electronic devices and human-machine interactions in the future.

From Plants to Wound Dressing and Transdermal Delivery of Bioactive Compounds

Transdermal delivery devices and wound dressing materials are constantly improved and upgraded with the aim of enhancing their beneficial effects, biocompatibility, biodegradability, and cost effectiveness. Therefore, researchers in the field have shown an increasing interest in using natural compounds as constituents for such systems. Plants, as an important source of so-called "natural products" with an enormous variety and structural diversity that still exceeds the capacity of present-day sciences to define or even discover them, have been part of medicine since ancient times. However, their benefits are just at the beginning of being fully exploited in modern dermal and transdermal delivery systems. Thus, plant-based primary compounds, with or without biological activity, contained in gums and mucilages, traditionally used as gelling and texturing agents in the food industry, are now being explored as valuable and cost-effective natural components in the biomedical field. Their biodegradability, biocompatibility, and non-toxicity compensate for local availability and compositional variations. Also, secondary metabolites, classified based on their chemical structure, are being intensively investigated for their wide pharmacological and toxicological effects. Their impact on medicine is highlighted in detail through the most recent reported studies. Innovative isolation and purification techniques, new drug delivery devices and systems, and advanced evaluation procedures are presented.

Physicochemical Characterization, Biocompatibility, and Antibacterial Properties of CMC/PVA/Calendula officinalis Films for Biomedical Applications

This study reports a carboxymethyl cellulose (CMC)/polyvinyl alcohol (PVA) composite film that incorporates Calendula officinalis (CO) extract for biomedical applications. The morphological, physical, mechanical, hydrophilic, biological, and antibacterial properties of CMC/PVA composite films with various CO concentrations (0.1%, 1%, 2.5%, 4%, and 5%) are fully investigated using different experiments. The surface morphology and structure of the composite films are significantly affected by higher CO concentrations. X-ray diffraction (XRD) and Fourier transform infrared spectrometry (FTIR) analyses confirm the structural interactions among CMC, PVA, and CO. After CO is incorporated, the tensile strength and elongation upon the breaking of the films decrease significantly. The addition of CO significantly reduces the ultimate tensile strength of the composite films from 42.8 to 13.2 MPa. Furthermore, by increasing the concentration of CO to 0.75%, the contact angle is decreased from 15.8° to 10.9°. The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay reveals that the CMC/PVA/CO-2.5% and CMC/PVA/CO-4% composite films are non-cytotoxic to human skin fibroblast cells, which is favorable for cell proliferation. Remarkably, 2.5% and 4% CO incorporation significantly improve the inhibition ability of the CMC/PVA composite films against Staphylococcus aureus and Escherichia coli. In summary, CMC/PVA composite films containing 2.5% CO exhibit the functional properties for wound healing and biomedical engineering applications.

Fabrication and characterization of colorimetric indicator for Salmon freshness monitoring using agar/polyvinyl alcohol gel and anthocyanin from different plant sources

In order to investigate the sensitivity of anthocyanins from different plant origin as indicators for salmon freshness, nine plant anthocyanins were extracted and fabricated into colorimetric sensor arrays to detect NH₃, trimethylamine (TMA), dimethylamine (DMA) to indicate salmon freshness. Rosella anthocyanin had the highest sensitivity for amines, ammonia and salmon. HPLC-MSS analysis indicated that Delphinidin-3 glucoside accounted for 75.48 % of the Rosella anthocyanin. UV-visible spectral analysis showed that the maximum absorbance band of Roselle anthocyanins for acid and alkaline forms were located at 525 nm and 625 nm which showed a relatively broader spectrum than other anthocyanins. An indicator film was fabricated by combining Roselle anthocyanin with agar and polyvinyl alcohol (PVA), which showed visible changes from red to green when employed to monitor the freshness of salmon stored at 4 °C. The ΔE value of Roselle anthocyanin indicator film was changed from 5.94 to >10. The ΔE value also can predict the chemical quality indicators of salmon effectively, especially with characteristic volatile components, and the predictive correlation coefficient was above 0.98. Therefore, the proposed indicating film showed great potential monitoring salmon freshness.

Bioengineered Water-Responsive Carboxymethyl Cellulose/Poly(vinyl alcohol) Hydrogel Hybrids for Wound Dressing and Skin Tissue Engineering Applications

The burden of chronic wounds is growing due to the increasing incidence of trauma, aging, and diabetes, resulting in therapeutic problems and increased medical costs. Thus, this study reports the synthesis and comprehensive characterization of water-responsive hybrid hydrogels based on carboxymethyl cellulose (CMC) and poly(vinyl alcohol) (PVA) using citric acid (CA) as the chemical crosslinking agent, with tunable physicochemical properties suitable to be applied as a wound dressing for soft tissue engineering applications. They were produced through an eco-friendly process under mild conditions. The hydrogels were designed and produced with flexible swelling degree properties through the selection of CMC molecular mass (Mw = 250 and 700 kDa) and degree of functionalization (DS = 0.81), degree of hydrolysis of PVA (DH > 99%, Mw = 84-150 kDa) associated with synthesis parameters, CMC/PVA ratio and extension of chemical crosslinking (CA/CMC:PVA ratio), for building engineered hybrid networks. The results demonstrated that highly absorbent hydrogels were produced with swelling degrees ranging from 100% to 5000%, and gel fraction from 40% to 80%, which significantly depended on the concentration of CA crosslinker and the presence of PVA as the CMC-based network modifier. The characterizations indicated that the crosslinking mechanism was mostly associated with the chemical reaction of CA carboxylic groups with hydroxyl groups of CMC and PVA polymers forming ester bonds, rendering a hybrid polymeric network. These hybrid hydrogels also presented hydrophilicity, permeability, and structural features dependent on the degree of crosslinking and composition. The hydrogels were cytocompatible with in vitro cell viability responses of over 90% towards model cell lines. Hence, it is envisioned that this research provides a simple strategy for producing biocompatible hydrogels with tailored properties as wound dressings for assisting chronic wound healing and skin tissue engineering applications.

Exploring the Potential of Alternate Inorganic Fibers for Automotive Composites

Composites are a promising material for high-specific strength applications; specifically, fiber-reinforced polymer composites (FRPCs) are in the limelight for their extraordinary mechanical properties. Amongst all FRPCs, carbon fiber reinforcements are dominant in the aerospace and automotive industry; however, their high cost poses a great obstacle in commercial-scale manufacturing. To this end, we explored alternate low-cost inorganic fibers such as basalt and rockwool as potential replacements for carbon fiber composites. In addition to fibrous inclusions to polymers, composites were also fabricated with inclusions of their respective particulates formed using ball milling of fibers. Considering automotive applications, composites' mechanical and thermo-mechanical properties were compared for all samples. Regarding mechanical properties, rockwool fiber and basalt fiber composites showed 30.95% and 20.77% higher impact strength than carbon fiber, respectively. In addition, rockwool and basalt fiber composites are less stiff than carbon and can be used in low-end applications in the automotive industry. Moreover, rockwool and basalt fiber composites are more thermally stable than carbon fiber. Thermogravimetric analysis of carbon fiber composites showed 10.10 % and 9.98 % higher weight loss than basalt and rockwool fiber composites, respectively. Apart from better impact and thermal properties, the low cost of rockwool and basalt fibers provides a key advantage to these alternate fibers at the commercial scale.