Convenient Agarose Preparation with Hydrogen Peroxide and Desulfation Process Analysis

Terahertz time-domain transmission spectroscopy of water and hydrogel thin films: Extraction of optical parameters and application to agarose gel characterization

Terahertz time-domain spectroscopy (THz-TDS) is an emerging optical technique that has potential applications in the characterization of (bio)materials. However, the complicated extraction of optical parameters from multi-layered and optically thin samples is a barrier towards its acceptance by applied scientists. Therefore, the aim of this work is to provide a straightforward approach for the extraction of the THz absorption coefficient and index of refraction profiles of aqueous thin films in a window-sample-window configuration, which is ubiquitous in many laboratories (i.e., sample in a cuvette). A numerical approach-based methodology that accounts for multiple layers, Fabry-Pérot effect, and sample thickness is elaborated which involves an optical interference model based on a tri-layer structure and a simple thickness estimation technique. This method was validated on water samples where a good agreement was found with the THz optical parameters of water reported in the literature, while the use of a commercial software resulted in erroneous optical parameters estimates when used without due regard to its limitations. A case study was then performed to demonstrate the ability of the proposed method to characterize agarose hydrogels with varying degree of sulfation. It was demonstrated that THz-TDS can provide insight into the hydration state of the agarose hydrogels, including the relative number of the hydrogen bonds between the hydroxyl moieties of water and the polysaccharide network which is perturbed by the presence of sulfate. The trend in the index of refraction profiles suggested microstructural differences between the agarose hydrogels, which were confirmed by visualizing the agarose network morphology using cryo-SEM imaging.

Preparation and characterization of agarose-sodium alginate hydrogel beads for the co-encapsulation of lycopene and resveratrol nanoemulsion

In the study, lycopene and resveratrol nanoemulsion hydrogel beads were prepared by using agarose‑sodium alginate as a carrier and the semi-interpenetrating polymer network technique, characteristics and morphologies were evaluated by scanning electron microscopy, fluorescence microscopy, rheological measurement. The synergistic antioxidant effect of lycopene and resveratrol was confirmed, the best synergistic antioxidant performance is achieved when the ratio of 1:1. To increase the solubility and improve the stability, the lycopene was prepared as solid dispersion added to the nanoemulsion. The encapsulation rate of lycopene and resveratrol reached 93.60 ± 2.94 % and 89.30 ± 1.75 %, respectively, and the cumulative release showed that the addition of agarose slowed down the release rate of the compound, which improves the applicability of lycopene and resveratrol and development of carriers for the delivery of different bioactive ingredients.

Extraction and Purification of Biopolymers from Marine Origin Sources Envisaging Their Use for Biotechnological Applications

Biopolymers are a versatile and diverse class of materials that has won high interest due to their potential application in several sectors of the economy, such as cosmetics, medical materials/devices, and food additives. In the last years, the search for these compounds has explored a wider range of marine organisms that have proven to be a great alternative to mammal sources for these applications and benefit from their biological properties, such as low antigenicity, biocompatibility, and biodegradability, among others. Furthermore, to ensure the sustainable exploitation of natural marine resources and address the challenges of 3R's policies, there is a current necessity to valorize the residues and by-products obtained from food processing to benefit both economic and environmental interests. Many extraction methodologies have received significant attention for the obtention of diverse polysaccharides, proteins, and glycosaminoglycans to accomplish the increasing demands for these products. The present review gives emphasis to the ones that can be obtained from marine biological resources, as agar/agarose, alginate and sulfated polysaccharides from seaweeds, chitin/chitosan from crustaceans from crustaceans, collagen, and some glycosaminoglycans such as chondroitin sulfate and hyaluronic acids from fish. It is offered, in a summarized and easy-to-interpret arrangement, the most well-established extraction and purification methodologies used for obtaining the referred marine biopolymers, their chemical structure, as well as the characterization tools that are required to validate the extracted material and respective features. As supplementary material, a practical guide with the step-by-step isolation protocol, together with the various materials, reagents, and equipment, needed for each extraction is also delivered is also delivered. Finally, some remarks are made on the needs still observed, despite all the past efforts, to improve the current extraction and purification procedures to achieve more efficient and green methodologies with higher yields, less time-consuming, and decreased batch-to-batch variability.

Biopolymers Used for Receptor Immobilization for Nickel-Detection Biosensors in Food

Food is humans' main source of nickel intake, which is responsible for the prevalence of allergic contact dermatitis and other pathological afflictions. While robust, the classical methods for nickel detection-atomic absorption spectrometry and inductively coupled plasma mass spectrometry-are expensive and laborious; in contrast, modern methods that utilize sensors-of which most are electrochemical-have rapid run times, are cost-effective, and are easily assembled. Here, we describe the use of four biopolymers (alginate, agar, chitosan, and carrageenan) for receptor immobilization on biosensors to detect nickel ions and use an optimization approach with three biopolymer concentrations to assay analytical performance profiles. We measured the total performance of screen-printed carbon electrodes immobilized with the biopolymer-sensor combinations using cyclic voltammetry (CV). Voltammetric behavior favored the carrageenan biosensor, based on performance characteristics measured using CV, with sensitivities of 2.68 (for 1% biopolymer concentration) and 2.08 (for 0.5% biopolymer concentration). Our results indicated that among the four biopolymer combinations, carrageenan with urease affixed to screen-printed electrodes was effective at coupling for nickel detection.

Extraction, Modification and Biomedical Application of Agarose Hydrogels: A Review

Numerous compounds present in the ocean are contributing to the development of the biomedical field. Agarose, a polysaccharide derived from marine red algae, plays a vital role in biomedical applications because of its reversible temperature-sensitive gelling behavior, excellent mechanical properties, and high biological activity. Natural agarose hydrogel has a single structural composition that prevents it from adapting to complex biological environments. Therefore, agarose can be developed into different forms through physical, biological, and chemical modifications, enabling it to perform optimally in different environments. Agarose biomaterials are being increasingly used for isolation, purification, drug delivery, and tissue engineering, but most are still far from clinical approval. This review classifies and discusses the preparation, modification, and biomedical applications of agarose, focusing on its applications in isolation and purification, wound dressings, drug delivery, tissue engineering, and 3D printing. In addition, it attempts to address the opportunities and challenges associated with the future development of agarose-based biomaterials in the biomedical field. It should help to rationalize the selection of the most suitable functionalized agarose hydrogels for specific applications in the biomedical industry.

In vitro fermentation of seaweed polysaccharides and tea polyphenol blends by human intestinal flora and their effects on intestinal inflammation

A combination of polysaccharides and tea polyphenols can enhance immune activity synergistically, depending on the type and structure of polysaccharides, but the mechanism remains unknown. This study is aimed to investigate the regulating effects of different seaweed polysaccharide (ι-carrageenan, agarose) and tea polyphenol blends on intestinal flora and intestinal inflammation using an in vitro ascending-transverse-descending colon fermentation system and RAW264.7 cell model. The results showed that seaweed polysaccharides in the presence of tea polyphenol were almost completely degraded at transverse colon fermentation for 36 h. Agarose significantly enhanced the butyric acid production content by increasing the abundance of Lachnospiraceae, whereas agarose and tea polyphenol blends did not have a synergistic effect. On the contrary, ι-carrageenan and tea polyphenol blends synergistically increased the abundance of beneficial bacteria (e.g., Bacteroidetes and Bifidobacterium) and promoted the production of short-chain fatty acids (SCFAs), such as isobutyric acid. Such changes tended to alter the impacts of different seaweed polysaccharides and tea polyphenol blends on intestinal inflammation. Among them, ι-carrageenan and tea polyphenol blends were the most effective in inhibiting lipopolysaccharide-induced NO, ROS, IL-6, and TNF-α production in RAW264.7 cells, indicating the alleviated intestinal inflammation. The results suggest that the seaweed polysaccharide and tea polyphenol blends have prebiotic potential and can benefit intestinal health.

Extraction, Purification, Characterization and Application in Livestock Wastewater of S Sulfur Convertase

Sulfide is a toxic pollutant in the farming environment. Microbial removal of sulfide always faces various biochemical challenges, and the application of enzymes for agricultural environmental remediation has promising prospects. In this study, a strain of Cellulosimicrobium sp. was isolated: numbered strain L1. Strain L1 can transform S^2-, extracellular enzymes play a major role in this process. Next, the extracellular enzyme was purified, and the molecular weight of the purified sulfur convertase was about 70 kDa. The sulfur convertase is an oxidase with thermal and storage stability, and the inhibitor and organic solvent have little effect on its activity. In livestock wastewater, the sulfur convertase can completely remove S^2-. In summary, this study developed a sulfur convertase and provides a basis for the application in environmental remediation.

Isolation and application of a mixotrophic sulfide-oxidizing Cohnella thermotolerans LYH-2 strain to sewage sludge composting for hydrogen sulfide odor control

To investigate the influences of sulfide oxidizing bacteria on H₂S odor control in sewage sludge composting, a facultative chemolithotroph strain was isolated and identified as Cohnella thermotolerans LYH-2. Strain LYH-2 decreased the initially added sulfide by 94.6% when glucose and NH₄Cl were used as the optimal energy substrates. The biotransformation of sulfide substrates followed first-order reaction kinetics, and the highest degradation rate constant (0.0537 h^-1) and bacterial dry weight (0.745 g/L) were obtained at 300 mg/L of initial sulfide. The C. thermotolerans strain was inoculated as the bacterial agent into the sewage sludge and rice husk composting in forced ventilation composting reactors for 25 d; the bacterial inoculation prolonged the thermophilic period by 2 d, decreased 35.4% of H₂S odor emission, and accelerated the composting process compared to the control group. The results demonstrated that C. thermotolerans inoculants effectively controlled H₂S emission and promoted maturity in sewage sludge composting.