Agar-tragacanth/silk fibroin hydrogel containing Zn-based MOF as a novel nanobiocomposite with biological activity.

In this study, a novel nanobiocomposite consisting of agar (Ag), tragacanth gum (TG), silk fibroin (SF), and MOF-5 was synthesized and extensively investigated by various analytical techniques and basic biological assays for potential biomedical applications. The performed Trypan blue dye exclusion assay indicated that the proliferation percentage of HEK293T cells was 71.19%, while the proliferation of cancer cells (K-562 and MCF-7) was significantly lower, at 10.74% and 3.33%. Furthermore, the Ag-TG hydrogel/SF/MOF-5 nanobiocomposite exhibited significant antimicrobial activity against both E. coli and S. aureus strains, with growth inhibition rates of 76.08% and 69.19% respectively. Additionally, the hemolytic index of fabricated nanobiocomposite was found approximately 19%. These findings suggest that the nanobiocomposite exhibits significant potential for application in cancer therapy and wound healing.

Gelatin/agar pH-indicator film based on cranberry extract loaded with linalool nanoparticle: Survey on physical, antimicrobial, and antioxidant properties.

In this study, linalool-nanoparticles (L-NPs) were prepared (encapsulation efficiency was 68.54 %) and introduced pH-indicator film based on cranberry-extract (CEF) to develop multifunctional smart films. XRD analysis and FTIR spectroscopy indicated that cranberry-extract (CE) and L-NPs were uniformly distributed in the gelatin/agar matrix and could change the intermolecular structure of the film. Color change of smart films showed that CE endowed the film with pH-sensitive property. As CE and L-NPs were added to the film, the water contact angle (WCA) was increased from 57.03° to 117.73°, the elongation at break (EAB) was increased from 12.30 % to 34.60 %. Additionally, the introduction of L-NPs enhanced the antioxidant activity (DPPH free radical scavenging rate increased from 26.80 % to 36.35 %) and antibacterial activity (against S. aureus and E. coli) of the smart film, which were verified by its retarding effect on pork spoilage.

Premise setting for sustainable developing adsorption in environmental remediation using graphitic carbon nitride@agar-derived porous carbon composite.

In the adsorption process for wastewater treatment, the adsorbent plays an important role. A composite adsorptive material composed of graphitic carbon nitride and agar-derived porous carbon (CNPC) was fabricated from simple precursors (melamine, thiourea, and agar) and through a facile procedure with different melamine and thiourea ratios. Characterization of CNPC proved a successful formation of a porous structure consisting of mesopores and macropores, wherein CNPC holds distinctive electrochemical (lowered resistance and higher specific capacity) and photochemical properties (lowered bandgap to 2.33 eV) thanks to the combination of graphitic carbon nitride (CN) and agar-derived porous carbon (PC). Inheriting the immanent nature, CNPC was subjected to the adsorption of methylene blue (MB) dye in an aqueous solution. The highest adsorption capacity was 133 mg/g for CNPC-4 which was prepared using a melamine to thiourea ratio of 4:4 - equivalent to the removal rate of 53.2 % and following the pseudo-I-order reaction rate. The effect of pH points out that pH 7 and 9 were susceptible to maximum removal and pretreatment is not required while the optimal ratio of 7.5 mg of MB and 30 mg of material was also determined to yield the highest performance. Furthermore, the reusability of the material for three consecutive cycles was evaluated based on two methods pyrolysis at 200 °C and photocatalytic degradation by irradiation under visible light. In general, the photocatalytic regeneration pathway is more ample and efficient than pyrolysis in terms of energy efficiency (saving energy over 10 times) and adsorption capacity stability. As a whole, the construction of accessible regenerative and stable adsorbent could be a venturing step into the sustainable development spearhead for industries.

Fabrication, structure, characterization and emulsion application of citrate agar.

In this study, citric acid successfully reacted with agar through the dry heat method, and citrate agar (CA) gel was used to stabilize O/W emulsions. The mechanisms of the CA structure and emulsion pH that affected emulsion stabilization were analyzed, and the application of CA gel emulsion (CAGE) was explored. Compared with native agar (NA), CA showed lower gel strength, higher transparency, and higher water contact angle. These changes indicate that a cross-linking reaction occurred, and it was demonstrated via FTIR and NMR. The emulsion properties were evaluated using particle size, ζ-potential, and the emulsification activity index. Results showed that CAGEs had a smaller particle size and lower ζ-potential than the native agar gel emulsion (NAGE). Meanwhile, confocal laser scanning microscopy confirmed that the CA gels stabilized the emulsions by forming a protective film around the oil droplets. Stability experiments revealed that CAGE (prepared with CA gel [DS = 0.145]) exhibited better stability than NAGE in the pH range of 3-11, and the rheological results further confirmed that the stability of the emulsions was influenced by the network structure and oil droplet interaction forces. Afterward, the application prospect of CAGE was evaluated by encapsulating vitamin D3 and curcumin.

Real-time monitoring of pork freshness using polyvinyl alcohol/modified agar multilayer gas-sensitive labels.

Accurate consumer perception of food packages should provide real-time feedback on any changes inside food packaging. Hence, a new multilayer gas-sensitive label (POA-12) was prepared using a layer-by-layer pouring method for simple, visual, and real-time detection of pork's freshness, while the front side was developed by immobilizing red carbon dots and fluorescein isothiocyanate in POA as indicator for volatile nitrogen, and the back side was created using bromothymol blue in POA as pH indicator. The swelling index of the multilayer gas-sensitive labels reduced from 159.19% to 148.36%, and the tensile strength increased from 25.52 MPa to 42.61 MPa. In addition, the POA-12 multilayer label showed a red-to-yellow fluorescence change as TVB-N increased from 6.84 to 31.4 and a yellow-brown-to-blue-green color change as pH increased from 5.74 to 7.24 when detecting pork samples. Thus, it provides dual-indicator monitoring that improves the accuracy and reliability of assessing the freshness of high-protein products.

Characterization of gelling agents in callus inducing media: Physical properties and their effect on callus growth.

In plant tissue culture, callus formation serves as a crucial mechanism for regenerating entire plants, enabling the differentiation of diverse tissues. Researchers have extensively studied the influence of media composition, particularly plant growth regulators, on callus behavior. However, the impact of the physical properties of the media, a well-established factor in mammalian cell studies, has received limited attention in the context of plant tissue culture. Previous research has highlighted the significance of gelling agents in affecting callus growth and differentiation, with Agar, Phytagel, and Gelrite being the most used options. Despite their widespread use, a comprehensive comparison of their physical properties and their subsequent effects on callus behavior remains lacking. Our study provides insights into optimizing plant tissue culture media by analyzing the physical properties of gelling agents and their impact on callus induction and differentiation. We compared the phenotypes of calli grown on media composed of these different gelling agents and correlated them to the physical properties of these media. We tested water retention, examined pore size using cryo-SEM, measured the media mechanical properties, and studied diffusion characteristics. We found that the mechanical properties of the media are the only quality correlated with callus phenotype.

Determination of minimum inhibitory concentrations using machine-learning-assisted agar dilution.

Effective policy to address the global threat of antimicrobial resistance requires robust antimicrobial susceptibility data. Traditional methods for measuring minimum inhibitory concentration (MIC) are resource intensive, subject to human error, and require considerable infrastructure. AIgarMIC streamlines and standardizes MIC measurement and is especially valuable for large-scale surveillance activities. MICs were measured using agar dilution for n = 10 antibiotics against clinical Enterobacterales isolates (n = 1,086) obtained from a large tertiary hospital microbiology laboratory. Escherichia coli (n = 827, 76%) was the most common organism. Photographs of agar plates were divided into smaller images covering one inoculation site. A labeled data set of colony images was created and used to train a convolutional neural network to classify images based on whether a bacterial colony was present (first-step model). If growth was present, a second-step model determined whether colony morphology suggested antimicrobial growth inhibition. The ability of the AI to determine MIC was then compared with standard visual determination. The first-step model classified bacterial growth as present/absent with 94.3% accuracy. The second-step model classified colonies as "inhibited" or "good growth" with 88.6% accuracy. For the determination of MIC, the rate of essential agreement was 98.9% (644/651), with a bias of -7.8%, compared with manual annotation. AIgarMIC uses artificial intelligence to automate endpoint assessments for agar dilution and potentially increases throughput without bespoke equipment. AIgarMIC reduces laboratory barriers to generating high-quality MIC data that can be used for large-scale surveillance programs. IMPORTANCE: This research uses modern artificial intelligence and machine-learning approaches to standardize and automate the interpretation of agar dilution minimum inhibitory concentration testing. Artificial intelligence is currently of significant topical interest to researchers and clinicians. In our manuscript, we demonstrate a use-case in the microbiology laboratory and present validation data for the model's performance against manual interpretation.

Statistical optimization of process variables for agarase production using Microbacterium sp. SS5 strain from non-marine sources.

Agar oligosaccharides are thought to be valuable biomolecules with high bioactivity potential, along with a wide range of applications and advantages. The current study aimed to optimize the culture parameters required to produce agarase enzyme and agar oligosaccharides from industrial waste agar. Microbacterium spp. strain SS5 was isolated from a non-marine source and could synthesize oligo derivatives for use in a variety of industries ranging from food to pharmaceuticals. In addition, the strain and culture conditions were optimized to maximize extracellular agarase production. The bacterium grew best at pH 5.0 - 9.0, with an optimal pH of 7.5 - 8.0; temperatures ranging from 25 to 45 °C, with an optimal of 35 °C; and carbon and nitrogen concentrations of 0.5% each. Plackett-Burman experimental design and response surface methods were used to optimize various process parameters for agarase production by Microbacterium spp. strain SS5. Using the Plackett-Burman experimental design, eleven process factors were screened, and agar, beef extract, CaCl2, and beginning pH were found as the most significant independent variables affecting agarase production with confidence levels above 90%. To determine the optimal concentrations of the identified process factors on agarase production, the Box- Behnken design was used. Agarase production by Microbacterium spp. strain SS5 after optimization was 0.272 U/mL, which was determined to be greater than the result obtained from the basal medium (0.132 U/mL) before screening using Plackett-Burman and BBD with a fold increase of 2.06.

Enhanced mechanical strength of vortex fluidic mediated biomass-based biodegradable films composed from agar, alginate and kombucha cellulose hydrolysates.

Biodegradable, biomass derived kombucha cellulose films with increased mechanical strength from 9.98 MPa to 18.18 MPa were prepared by vortex fluidic device (VFD) processing. VFD processing not only reduced the particle size of kombucha cellulose from approximate 2 µm to 1 µm, but also reshaped its structure from irregular to round. The increased mechanical strength of these polysaccharide-derived films is the result of intensive micromixing and high shear stress of a liquid thin film in a VFD. This arises from the incorporation at the micro-structural level of uniform, unidirectional strings of kombucha cellulose hydrolysates, which resulted from the topological fluid flow in the VFD. The biodegradability of the VFD generated polymer films was not compromised relative to traditionally generated films. Both films were biodegraded within 5 days.

Detection, production, modification, and application of arylsulfatases.

Arylsulfatase is a subset of sulfatase which catalyzes the hydrolysis of aryl sulfate ester. Arylsulfatase is widely distributed among microorganisms, mammals and green algae, but the arylsulfatase-encoding gene has not yet been found in the genomes of higher plants so far. Arylsulfatase plays an important role in the sulfur flows between nature and organisms. In this review, we present the maturation and catalytic mechanism of arylsulfatase, and the recent literature on the expression and production of arylsulfatase in wild-type and engineered microorganisms, as well as the modification of arylsulfatase by genetic engineering are summarized. We focus on arylsulfatases from microbial origin and give an overview of different assays and substrates used to determine the arylsulfatase activity. Furthermore, the researches about arylsulfatase application on the field of agar desulfation, soil sulfur cycle and soil evaluation are also discussed. Finally, the perspectives concerning the future research on arylsulfatase are prospected.

Bubble dynamics and speed of jets for needle-free injections produced by thermocavitation.

Significance: The number of injections administered has increased dramatically worldwide due to vaccination campaigns following the COVID-19 pandemic, creating a problem of disposing of syringes and needles. Accidental needle sticks occur among medical and cleaning staff, exposing them to highly contagious diseases, such as hepatitis and human immunodeficiency virus. In addition, needle phobia may prevent adequate treatment. To overcome these problems, we propose a needle-free injector based on thermocavitation. Aim: Experimentally study the dynamics of vapor bubbles produced by thermocavitation inside a fully buried 3D fused silica chamber and the resulting high-speed jets emerging through a small nozzle made at the top of it. The injected volume can range from ∼0.1 to 2 µL per shot. We also demonstrate that these jets have the ability to penetrate agar skin phantoms and ex-vivo porcine skin. Approach: Through the use of a high-speed camera, the dynamics of liquid jets ejected from a microfluidic device were studied. Thermocavitation bubbles are generated by a continuous wave laser (1064 nm). The 3D chamber was fabricated by ultra-short pulse laser-assisted chemical etching. Penetration tests are conducted using agar gels (1%, 1.25%, 1.5%, 1.75%, and 2% concentrations) and porcine tissue as a model for human skin. Result: High-speed camera video analysis showed that the average maximum bubble wall speed is about 10 to 25 m/s for almost any combination of pump laser parameters; however, a clever design of the chamber and nozzle enables one to obtain jets with an average speed of ∼70 m/s. The expelled volume per shot (0.1 to 2 µl) can be controlled by the pump laser intensity. Our injector can deliver up to 20 shots before chamber refill. Penetration of jets into agar of different concentrations and ex-vivo porcine skin is demonstrated. Conclusions: The needle-free injectors based on thermocavitation may hold promise for commercial development, due to their cost and compactness.

Synthesis, characterization, antibacterial and emulsifying properties of agar benzoate.

Agar benzoate (AB) with different degrees of substitution (DS) was synthesized by the esterification of agar and benzoic anhydride in aqueous solution. The DS could be regulated by adjusting composition ratio, pH, and temperature. Its chemical structure was determined by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). 13C NMR spectrum of the AB suggested the main substitution occurred at the C-6 in the d-galactopyranose. Cryo-scanning electron microscopy (Cryo-SEM) showed that the aperture of AB was larger than that of agar. The thermal performance of AB decreased slightly, but this did not affect its performance. AB showed the highest relative antibacterial activity against Escherichia coli, S. aureus and Alternaria alternata, reaching 100 % (AB 20 g/L), 100 % (AB 40 g/L) and 19.35 % (7 d incubation), respectively. Moreover, the obtained AB possessed good emulsion stability. These antibacterial AB have broad application prospects in the field of fruit and vegetable preservation.

Super absorbent glutaric anhydride-modified agar: Structure, properties, and application in biomaterial delivery.

Agar was modified with glutaric anhydride (GA) in this study to expand its application in food and medicine. Glutaric anhydride-modified agar (GAR) can maintain high gel strength (1247.4 g/cm2) and improved transparency (82.7 %). The esterified agar formed by GA further formed a cross-linking molecule structure by increasing the reaction temperature. Notably, excellent freeze-thaw stability (24.1 %) and swelling property (3116.6 %) of GAR indicated that the carboxyl-terminal of modified agar improves its affinity with water. Therefore, satisfactory water permeability and expansive stone enable agar films to achieve high water absorption. Furthermore, GAR films exhibit a specific absorption capacity of tetracycline hydrochloride in weak acid solution, thereby suggesting its potential application as a sustainable drug delivery carrier. Finally, the structure of the modified agar was analyzed to explain the mechanism of binding water. Cryo-scanning electron microscopy (SEM) depicted the porous structure of the agar gel responsible for swelling, drug loading, and release. Low-field NMR results showed that GA improves agar gel's binding and free water content. According to our research results, these GAR hydrogel membranes with excellent properties have the potential to be used as effective drug delivery materials.

Reproducible switching between a walled and cell wall-deficient lifestyle of actinomycetes using gradient agar plates.

The cell wall is a shape-defining structure that envelopes almost all bacteria, protecting them from biotic and abiotic stresses. Paradoxically, some filamentous actinomycetes have a natural ability to shed their cell wall under influence of hyperosmotic stress. These wall-deficient cells can revert to their walled state when transferred to a medium without osmoprotection but often lyse due to their fragile nature. Here, we designed plates with an osmolyte gradient to reduce cell lysis and thereby facilitating the transition between a walled and wall-deficient state. These gradient plates allow determining of the osmolyte concentration where switching takes place, thereby enabling careful and reproducible comparison between mutants affected by switching. Exploring these transitions could give valuable insights into the ecology of actinomycetes and their biotechnological applications.

Seaweed polysaccharides: Emerging extraction technologies, chemical modifications and bioactive properties.

Nowadays, consumers are increasingly aware of the relationship between diet and health, showing a greater preference of products from natural origin. In the last decade, seaweeds have outlined as one of the natural sources with more potential to obtain bioactive carbohydrates. Numerous seaweed polysaccharides have aroused the interest of the scientific community, due to their biological activities and their high potential on biomedical, functional food and technological applications. To obtain polysaccharides from seaweeds, it is necessary to find methodologies that improve both yield and quality and that they are profitable. Nowadays, environmentally friendly extraction technologies are a viable alternative to conventional methods for obtaining these products, providing several advantages like reduced number of solvents, energy and time. On the other hand, chemical modification of their structure is a useful approach to improve their solubility and biological properties, and thus enhance the extent of their potential applications since some uses of polysaccharides are still limited. The present review aimed to compile current information about the most relevant seaweed polysaccharides, available extraction and modification methods, as well as a summary of their biological activities, to evaluate knowledge gaps and future trends for the industrial applications of these compounds.Key teaching pointsStructure and biological functions of main seaweed polysaccharides.Emerging extraction methods for sulfate polysaccharides.Chemical modification of seaweeds polysaccharides.Potential industrial applications of seaweed polysaccharides.Biological activities, knowledge gaps and future trends of seaweed polysaccharides.

Synthesis and characterization Agar/GO/ZnO NPs nanocomposite for removal of methylene blue and methyl orange as azo dyes from food industrial effluents.

Herein, with using graphene oxide (GO), agar and ZnO NPs was synthesized as nanocomposite to removal of dyes contaminants from food industry effluents. Synthesis and characterization of the nanocomposite adsorbent were carried out by FTIR, XRD, FE-SEM, TEM, EDX and DLS analyses. The effects of various parameters such as pH, initial dye concentration, contact time and temperature on the removal of methylene blue (MB) and methyl orange (MO) as azo dyes were investigated. The used nanocomposite can be effective in the adsorption of dyes due to their different functional groups. The Freundlich and Langmuir models were used to investigate the isotherm of contaminants removal. The results showed that the removal of methylene blue and methyl orange dyes followed the Freundlich isotherm, and the values of the R2 correlation coefficient for agar/GO, and agar/GO/ZnO nanocomposites for MB dye was 0.9640 and 0.9977, respectively, and for dye MO, 0.9918 and 0.9683, respectively. The maximum removal percentages for MB and MO dyes were 88% and 91%, respectively.

Headspace control and antimicrobials: Inhibition strategies to prevent the growth of Alicyclobacillus acidoterrestris in orange juice.

Alicyclobacillus acidoterrestris can cause spoilage in orange juice that leads to consumer rejection. Six different orange juices were physiochemically characterized (pH, total soluble solids, titratable acidity, total polyphenols and vitamin C). A bottle for each sampling point per juice was filled (headspace: 40% volume) and inoculated with 102 -103 CFU per ml of A. acidoterrestris ATCC® 49025™ (heat shocked before inoculation: 75°C, 20 min). Samples were stored for 21 days at 45 ± 1°C and plate counted periodically on acidified YSG agar (pH 3·7) incubated at 45 ± 1°C for 3 days. The effect of headspace (6% versus 40% volume) on A. acidoterrestris growth was also evaluated. The effect of nisin (0·006, 0·003, 0·0015, and 0·00075%), sodium benzoate (0·1%), potassium sorbate (0·1%) and a mix of benzoate and sorbate (0·05% each) on A. acidoterrestris was additionally addressed. Alicyclobacillus acidoterrestris reached up to 107 CFU per ml in five of the six juices in less than 1 week. Headspace significantly impacted (P < 0·05) A. acidoterrestris maximum population, which reached the critical value of 5 log CFU per ml at 40% headspace. All preservatives, regardless of concentration, showed a bacteriostatic effect during 22 days of storage with no significant differences amongst treatments (P > 0·05).

Effects of seawater sulfur starvation and enrichment on Gracilaria gracilis growth and biochemical composition.

The genus Gracilaria, largest biomass producer in coastal regions, encompasses a wide range of species including Gracilaria gracilis. Nowadays, there is a spate of interest in its culture in lagoon where the water sulfate concentration is variable. A laboratory culture was carried out to determine the sulfate concentration effect on their growth as well as their biochemical composition, which were 2.5, 27 or 50 mM, referred to as SSS (sulfur starved seawater), SW (seawater) and SES (sulfur enriched seawater).We found that the sulfate content of the surrounding medium is a key parameter influencing both the alga growth and its composition. However, seawater proved to be the most suitable environment to sustain alga growth, proteins, R-phycoerythrin and agar yields, but sulfur enrichment and starvation affects them. The sulfate degree of agar and therefore its quality is related to the medium sulfate concentration. We conclude that sulfur starvation (2.5 mM) for three weeks, led to severe growth retardation, lower agar yield and quality and indicated the limit potential of G. gracilis for mariculture under these conditions. These results demonstrated that the success of G. gracilis culture in the lagoon is feasible if sulfate concentration is closer to that of seawater.

Emulsion gels and oil-filled aerogels as curcumin carriers: Nanostructural characterization of gastrointestinal digestion products.

Agar and κ-carrageenan emulsion gels and oil-filled aerogels were investigated as curcumin carriers and their structure and mechanical properties, as well as their structural changes upon in vitro gastrointestinal digestion were characterized. Agar emulsion gels presented stiffer behaviour, with smaller and more homogeneous oil droplets (ϕ âˆ¼ 12 µm) than those from κ-carrageenan (ϕ âˆ¼ 243 µm). The structure of κ-carrageenan gels was characterized by the presence of rigid swollen linear chains, while agar produced more branched networks. After simulated gastrointestinal digestion bile salt lamellae/micelles (∼5 nm) and larger vesicles of partially digested oil (Rg âˆ¼ 20-50 nm) were the predominant structures, being their proportion dependent of the polysaccharide type and the physical state of the gel network. The presence of curcumin induced the formation of larger vesicles and limited the formation of mixed lamellae/micelles.

Simplified Green's function for surface waves in quasi-incompressible elastic plates with application to elastography.

Surface wave elastography is a growing method to estimate the elasticity in soft solids. It is particularly useful in the case of agrifoods like meat, cheese, or fruits because it does not require major infrastructure or large equipment and could be developed in portable devices. However, estimating the shear elastic properties from surface wave measurements is not straightforward. The shear wavelength in those materials is cm sized for the excitation frequencies usually employed in elastography (∼102 Hz), and the size of samples is comparable to it. Thus, the surface wave speed is frequency dependent with no direct relation to the shear wave speed. In this work we propose a simplified Green's function for soft solid elastic plates which allows to retrieve the shear elasticity from near field measurements. The model is compared with experimental results obtained in agar-gelatin phantoms and food samples (cheese and bovine liver). The results show a good overall agreement although improvements can be achieved by incorporating diffraction and viscosity to the model.