Red algae-derived k-carrageenan-based proton-conducting electrolytes for the wearable electrical devices

Banana sheath cellulose extraction and incorporation into pectin/carrageenan film employing linalool: fabrication and comprehensive characterisation of physical and antimicrobial properties as potential food packaging applications

This study explores the use of banana sheath cellulose (BSC), extracted from banana sheath fibres, as a reinforcing agent in high methoxyl pectin/κ-carrageenan (PEC/CAR) films. BSC was characterised using XRD, FTIR, SEM, and TGA analyses and incorporated into PEC/CAR films. To further enhance functionality, linalool was added to create antimicrobial active packaging. Rheological analysis revealed shear-thinning behavior in the film-forming solutions. FTIR showed that BSC increased tensile strength through hydrogen bonding, while linalool's hydrophobicity reduced tensile strength. XRD results indicated that BSC increased film crystallinity, improving mechanical properties, while linalool reduced crystallinity. Thermal stability improved with BSC and linalool, raising peak degradation temperatures. BSC reduced oxygen permeability from 5.26 to 2.95 cc.mm/m2.day, while linalool slightly increased it to 7.09 cc.mm/m2.day. In contrast, BSC significantly increased the water vapor permeability from 0.089 ± 0.011 to 0.299 ± 0.010 g·mm/m2·day, but the addition of 15 % linalool reduced it to 0.255 ± 0.006 g·mm/m2·day. Although linalool reduced the mechanical strength of the films, it significantly enhanced the antimicrobial properties. However, the addition of BSC helped counteract the reduction in mechanical performance caused by linalool, resulting in a balanced combination of strength and antimicrobial effectiveness of the film.

Mitochondrial activation via calcium peroxide/carrageenan/soybean lecithin-derived polypyrrole phototherapeutic microparticles

Mitochondria, often referred to as the "powerhouses" of eukaryotic cells, play a critical role in maintaining cellular homeostasis and supporting essential life functions, particularly in cell survival and apoptosis. This study introduces a composite formulation-combining carrageenan (Car), calcium peroxide (CaO2), and microparticles, derived from soybean oil lecithin, enhanced with photothermally active polypyrrole (PPy)-to create Car-Lec-PPy MP, aimed at promoting mitochondrial activation in cells. The investigation focuses on intercellular mitochondrial transfer and activation as a therapeutic strategy. The formulation seeks to stimulate mitochondrial biogenesis and enhance cellular resilience through targeted mitochondrial activation, leveraging the synergistic effects of near-infrared (NIR) therapy. In the in vivo experiment, phototherapeutic Car-Lec-PPy MP was administered to rodent muscle tissue. The results showed increased expression of heat-shock proteins and reduced oxidative stress in the treated muscle. Preliminary findings suggest that this approach not only boosts mitochondrial activity but also improves cell proliferation and survival, presenting significant potential for applications in regenerative medicine and cellular therapy.

κ-carrageenan - Gelatin hydrogel embedding carvacrol loaded gold nanobipyramids for treating prostate cancer via fractionated photothermal-chemotherapy

Conventional treatment of prostate cancer need more specificity, and higher efficiency. The present work is the first attempt to utilize hydrogel-loaded carvacrol-based chemotherapy with fractionated photothermal therapy (F-PTT) using a 635 nm laser for its treatment. Gold nanobipyramids (AuNBPs) were used as drug carrier and photosensitizer. A marine-derived hydrogel (AuNBP-HG) was fabricated and physicochemically characterized. A 635 nm NIR light was used for the fractionated PTT in three cycles of treatment on different days at varying power densities for 5 min. The efficiency of single and dual treatments was experimented in vitro and in vivo. The results showed that the dual therapy imparted a better effect than monotherapy. The AuNBP-CVL synthesized was nearly 50 nm and efficiently loaded within AuNBP-HG, displaying thermal responsiveness, a good sol-gel transition, a controlled drug release rate, and high stability. In vitro evaluation demonstrated that the F-PTT evinced stability during temperature rise without damaging healthy surrounding tissue. In vivo study revealed that a stable temperature rise up to 60 °C by the 635 nm NIR light due to photosensitization of AuNBP and sustained CVL release from AuNBP-HG into the tumor microenvironment exhibited successful thermal ablation of the cancer cells. Histological analysis confirmed that the uniform suspension of AuNBP within cancer tissues might have enhanced tumor cell lysis during the dual therapy. Western blot analysis exhibited that the cellular death could result from the upregulation of pJNK and p53 protein. In conclusion, the current study illustrated that dual therapy could be a feasible alternative to non-target specific and invasive traditional therapies against prostate cancer.

Fabrication of smart nanogel based on carrageenan and green coffee extract as a long-term antifouling agent to improve biofilm prevention in food production

This study investigates the extract of the bioactive compounds from green coffee extract (GCE) and the loading of two different concentrations of GCE (1% and 2%) onto carrageenan nanogels (CAR NGs) to compare their antibacterial and antibiofilm effects with unloaded nanogels (NGs). The bioactive compounds of GCE were characterized using GC-MS analysis. The GCE1 and GCE2 were successfully deposited onto the surface of CAR NGs. The antibacterial and antibiofilm potential of prepared NGs were conducted against some foodborne pathogens (E. coli O157, Salmonella enterica, Staphylococcus aureus, and Listeria monocytogenes). The results of GC-MS analysis indicated that there were identified 16 bioactive compounds in GCE, including caffeine (36.27%), Dodemorph (9.04%), and D-Glycero-d-ido-heptose (2.44%), contributing to its antimicrobial properties. The antibacterial coatings demonstrated a notable antimicrobial effect, showing zone of inhibition (ZOI) diameters of up to 37 mm for GCE2 loaded CAR NGs. The minimum inhibitory concentration (MIC) values for GCE2 loaded CAR NGs were 80 ppm for E. coli O157, and 120 ppm for S. enterica, S. aureus, and L. monocytogenes, achieving complete bacterial inactivation within 10-15 min of exposure. Both GCE1 and GCE2 loaded CAR NGs significantly reduced biofilm cell densities on stainless steel (SS) materials for E. coli O157, S. enterica, S. aureus, and L. monocytogenes, with reductions ranging from 60% to 95%. Specifically, biofilm densities were reduced by up to 95% for E. coli O157, 89% for S. enterica, 85% for S. aureus, and 80% for L. monocytogenes. Results of the toxicity evaluation indicated that the NGs were non-toxic and biocompatible, with predicted EC50 values proved their biocompatibility and safety. These results recommended that GCE loaded CAR NGs are promising as natural antimicrobial agents for enhancing food safety and extending shelf life. Further, the study concluded that incorporating GCE into CAR NGs is an effective strategy for developing sustainable antimicrobial coatings for the food industry and manufacturing.

Injectable biocomposite cement: A dual-setting formula with magnesium potassium phosphate and κ-carrageenan hydrogel for orthopedic advancements

Magnesium phosphate-based cements are highly regarded for their bioactive properties, making them excellent candidates as bone substitutes. Despite their promising attributes, challenges such as high reaction temperature, limited injectability, and brittleness limit their application. This study introduces a dual-setting biocomposite cement, which encompasses both cement hydration and hydrogel's cross-linking. The composition features magnesium potassium phosphate (MKP) combined with ionically cross-linked kappa-carrageenan (kC) plasticized with sorbitol (Sor). The investigation delves into the properties of the resultant biocomposite, with a particular focus on evaluating kC incorporation's influence on the main MKP properties. Our findings reveal that those biocomposites offer multiple benefits over traditional ceramic cements. The main advantages include: a longer setting time (up to ~15 min), lower setting temperature (~45 °C), different crystalline phase (bobierrite), better wettability (~22°), and improved injectability of the paste characterized by more stable cohesion. Specifically, the MKP (4:1 Mg/P ratio) with 1.5 % kC and Sor hydrogel obtained with 3.0 g/mL powder-to-liquid ratio demonstrated the most promising properties with no adverse effects on the microstructure diversity, the mechanical strength, the porosity, the biodegradation rate, and the osteoblasts cytocompatibility. Overall, our research indicates that these innovative cements hold significant potential for biomedical applications, especially minimally invasive orthopedic procedures.

Piezoelectric Behaviour in Biodegradable Carrageenan and Iron (III) Oxide Based Sensor

This paper is dedicated to the research of phenomena noticed during tests of biodegradable carrageenan-based force and pressure sensors. Peculiar voltage characteristics were noticed during the impact tests. Therefore, the sensors' responses to impact were researched more thoroughly, defining time-dependent sensor output signals from calibrated energy impact. The research was performed using experimental methods when a free-falling steel ball impacted the sensor material to create relatively definable impact energy. The sensor's output signal, which is analogue voltage, was registered using an oscilloscope and transmitted to the PC for further analysis. The obtained results showed a very interesting outcome, where the sensor, which was intended to be piezoresistive, demonstrated a combination of behaviour typical for galvanic cells and piezoelectric material. It provides a stable DC output that is sensitive to the applied statical pressure, and in case of a sudden impact, like a hit, it demonstrates piezoelectric behaviour with some particular effects, which are described in the paper as proton transfer in the sensor-sensitive material. Such phenomena and sensor design are a matter of further development and research.

Algae-Based Biopolymers for Batteries and Biofuel Applications in Comparison with Bacterial Biopolymers-A Review

Algae-based biopolymers can be used in diverse energy-related applications, such as separators and polymer electrolytes in batteries and fuel cells and also as microalgal biofuel, which is regarded as a highly renewable energy source. For these purposes, different physical, thermochemical, and biochemical properties are necessary, which are discussed within this review, such as porosity, high temperature resistance, or good mechanical properties for batteries and high energy density and abundance of the base materials in case of biofuel, along with the environmental aspects of using algae-based biopolymers in these applications. On the other hand, bacterial biopolymers are also often used in batteries as bacterial cellulose separators or as biopolymer network binders, besides their potential use as polymer electrolytes. In addition, they are also regarded as potential sustainable biofuel producers and converters. This review aims at comparing biopolymers from both aforementioned sources for energy conversion and storage. Challenges regarding the production of algal biopolymers include low scalability and low cost-effectiveness, and for bacterial polymers, slow growth rates and non-optimal fermentation processes often cause challenges. On the other hand, environmental benefits in comparison with conventional polymers and the better biodegradability are large advantages of these biopolymers, which suggest further research to make their production more economical.

Self-extinguished and flexible cation exchange membranes based on modified K-Carrageenan/PVA double network hydrogels for electrochemical applications

It is highly desired and yet challenging to develop eco-friendly cation exchange membranes with a combination of good mechanical, electrochemical, and biocompatible properties with a rational economic efficiency for given applications. In this study, new biocompatible double network (DN) hydrogels were prepared based on a blend of modified K-Carrageenan (KC) and polyvinyl alcohol (PVA). Acrylic acid (AA)-grafted KC (KC-g-(PAA)) and (AA-co-tertbutyl acrylate (TBA))-grafted KC (KC-g-P(AA-co-TBA)) were synthesized through an in situ free radical copolymerization. The grafted copolymers were blended with PVA and mixed with ZrOCl₂/KCl and glutaraldehyde (Glu) as the physical and chemical cross-linkers, respectively to produce KC-g-P(AA)/PVA and KC-g-P(AA-co-TBA)/PVA DN hydrogels. The membranes were prepared by a solution casting method. Various techniques were carried out to compare the structural, thermal, mechanical, flammability, and electrochemical properties of the membranes with those of the cross-linked KC, PVA, and KC/PVA membranes. The KC-g-P(AA-co-TBA)/PVA DN membrane showed more desirable properties as the cation exchange membrane with water uptake of 70.7 %, ion exchange capacity of 0.47 meq H⁺ /g, the ionic conductivity of 1.99 × 10^-2 S/cm², and elongation at break of 71.8 %. The prepared biopolymer membrane is very cost-effective and self-extinguished with admissible conductivity for electrochemical applications.

Preparation and Characterization of Super-Absorbing Gel Formulated from κ-Carrageenan-Potato Peel Starch Blended Polymers

κ-carrageenan is useful for its superior gelling, hydrogel, and thickening properties. The purpose of the study was to maximize the hydrogel properties and water-absorbing capacity of κ-carrageenan by blending it with starch from potato peels to be used as safe and biodegradable water-absorbent children’s toys. The prepared materials were analyzed using FTIR and Raman spectroscopy to analyze the functional groups. Results showed that there was a shift in the characteristic peaks of starch and κ-carrageenan, which indicated their proper reaction during blend formation. In addition, samples show a peak at 1220 cm⁻¹ corresponding to the ester sulfate groups, and at 1670 cm⁻¹ due to the carbonyl group contained in D-galactose. SEM micrographs showed the presence of rough surface topology after blending the two polymers, with the appearance of small pores. In addition, the presence of surface cracks indicates the biodegradability of the prepared membranes that would result after enzymatic treatment. These results are supported by surface roughness results that show the surface of the κ-carrageenan/starch membranes became rougher after enzymatic treatment. The hydrophilicity of the prepared membranes was evaluated from contact angle (CA) measurements and the swelling ratio. The swelling ratio of the prepared membranes increased gradually as the starch ratio increased, reaching 150%, while the water-uptake capacity increased from 48 ± 4% for plain κ-carrageenan to 150 ± 5% for 1:2 κ-carrageenan/starch blends. The amylase enzyme showed an effective ability to degrade both the plain κ-carrageenan and κ-carrageenan/starch membranes, and release glucose units for up to 236 and 563, respectively. According to these results, these blends could be effectively used in making safe and biodegradable molded toys with superior water-absorbing capabilities.

A Protein-Based Free-Standing Proton-Conducting Transparent Elastomer for Large-Scale Sensing Applications

A most important endeavor in modern materials' research is the current shift toward green environmental and sustainable materials. Natural resources are one of the attractive building blocks for making environmentally friendly materials. In most cases, however, the performance of nature-derived materials is inferior to the performance of carefully designed synthetic materials. This is especially true for conductive polymers, which is the topic here. Inspired by the natural role of proteins in mediating protons, their utilization in the creation of a free-standing transparent polymer with a highly elastic nature and proton conductivity comparable to that of synthetic polymers, is demonstrated. Importantly, the polymerization process relies on natural protein crosslinkers and is spontaneous and energy-efficient. The protein used, bovine serum albumin, is one of the most affordable proteins, resulting in the ability to create large-scale materials at a low cost. Due to the inherent biodegradability and biocompatibility of the elastomer, it is promising for biomedical applications. Here, its immediate utilization as a solid-state interface for sensing of electrophysiological signals, is shown.

Enhanced ionic conductivity and lithium dendrite suppression of polymer solid electrolytes by alumina nanorods and interfacial graphite modification

Poor room-temperature ionic conductivity and lithium dendrite formation are the main issues of solid electrolytes. In this work, rod-shaped alumina incorporation and graphite coating were simultaneously applied to poly (propylene carbonate) (PPC)-based polymer solid electrolytes (Wang et al., 2018). The obtained alumina modified solid electrolyte membrane (Al-SE) achieves a high ionic conductivity of 3.48 × 10^-4 S/cm at room temperature with a wide electrochemical window of 4.6 V. The assembled NCM622/Al-SE/Li solid-state battery exhibits initial discharge capacities of 198.2 mAh/g and 177.5 mAh/g at the current density of 0.1 C and 0.5 C, with the remaining capacities of 165.8 mAh/g and 161.3 mAh/g after 100 cycles respectively. The rod-shaped structure of Al₂O₃ provides fast transport channels for lithium ions and its Lewis acidity promotes the dissociation of lithium salts and release of free lithium ions. The lithiophilic Al₂O₃ and Graphite form intimate contact with metallic Li and create fast Li⁺ conductive layers of Li-Al-O layer and LiC₆ layer, thus facilitating the uniform deposition of Li and inhibiting Li dendrite formation during long-term cycling. This kind of composite Al-SE is expected to provide a promising alternative for practical application in solid electrolytes.