Infection-Free and Enhanced Wound Healing Potential of Alginate Gels Incorporating Silver and Tannylated Calcium Peroxide Nanoparticles.

The treatment of chronic wounds involves precise requirements and complex challenges, as the healing process cannot go beyond the inflammatory phase, therefore increasing the healing time and implying a higher risk of opportunistic infection. Following a better understanding of the healing process, oxygen supply has been validated as a therapeutic approach to improve and speed up wound healing. Moreover, the local implications of antimicrobial agents (such as silver-based nano-compounds) significantly support the normal healing process, by combating bacterial contamination and colonization. In this study, silver (S) and tannylated calcium peroxide (CaO2@TA) nanoparticles were obtained by adapted microfluidic and precipitation synthesis methods, respectively. After complementary physicochemical evaluation, both types of nanoparticles were loaded in (Alg) alginate-based gels that were further evaluated as possible dressings for wound healing. The obtained composites showed a porous structure and uniform distribution of nanoparticles through the polymeric matrix (evidenced by spectrophotometric analysis and electron microscopy studies), together with a good swelling capacity. The as-proposed gel dressings exhibited a constant and suitable concentration of released oxygen, as shown for up to eight hours (UV-Vis investigation). The biofilm modulation data indicated a synergistic antimicrobial effect between silver and tannylated calcium peroxide nanoparticles, with a prominent inhibitory action against the Gram-positive bacterial biofilm after 48 h. Beneficial effects in the human keratinocytes cultured in contact with the obtained materials were demonstrated by the performed tests, such as MTT, LDH, and NO.

Textural Restoration of Broiler Breast Fillets with Spaghetti Meat Myopathy, Using Two Alginate Gels Systems.

The effects of salt-sensitive alginate ("A") and a two-component salt-tolerant alginate system ("B") used at a 0.5% or 1.0% level were evaluated in normal breast (NB) chicken fillets and in spaghetti meat (SM) fillets. Minced raw and cooked SM samples showed higher cooking loss (p < 0.05) and lower penetration force compared to NB meat. Both alginate systems significantly raised the penetration force in raw samples and decreased cooking loss (p < 0.05). Adding 1% of "A" or 0.5% "B" to SM, without salt, resulted in a similar penetration force as the cooked NB meat, while 1% "B" with salt resulted in a higher penetration force. Excluding salt from SM samples while adding alginate "A" or "B" improved texture profiles, but not to the same level as using NB without additives. Overall, salt, together with alginate "B", improved the texture of SM to that of normal meat without myopathy.

Textural, mechanical, and microstructural properties of restructured pimiento alginate-guar gels.

Textural, mechanical, microstructural, and thermal properties of reconstituted pimiento alginate-guar gels subjected to thermal and mechanical stresses during pasteurization process were investigated. Alginate-guar gelling system at ratio 2:1 at different calcium chloride concentrations (2-8%) and varying acid conditions including citric and lactic acid 1% were evaluated. Textural profile analysis parameters viz. hardness, springiness, gumminess, cohesiveness, adhesiveness as well as mechanical properties, structural, thermal, and morphological characteristics of pimiento strips were examined. Gel strength and elasticity of pimiento strips were increased at higher calcium levels. Fracturability was decreased clearly revealed the gel system, regain its strength in spite of high pulp content (25%) and can maintain its own structure. Increase in hardness and reduction in springiness showed loss of elasticity, which may be attributed to the gel shrinkage during thermal processing, making it more compact and dense. Therefore, the restructured pimiento strips were completely thermo stable at pasteurization temperature. By increasing alginate and calcium level in the pimiento strip, glass transition temperature was reduced from 112 to 98°C. Fourier transform infrared spectroscopy studies confirmed that the gel network structure at acidic conditions was stable and acid type did not has significant effect on the chemical interactions. The microstructural results showed ellipsoidal and compact structure in which can be an evidence of high elasticity and rigidity of pimiento gels. These results completely approved the high elasticity and rigidity of the pimiento strips and their ability to sustain successfully thermal and mechanical stresses with appreciable textural integrity during processing such as pasteurization. PRACTICAL APPLICATIONS: Restructured pimiento strip for stuffing into cocktail olives is a challenging problem in binary composite hydrogels of alginate and guar gum. The strips should be designed to be strong enough to handle mechanically and cut easily without tearing. Furthermore, it had to withstand to pasteurization process and be flexible to bend like a hairpin into the pit hole of olive. In addition, it also had low syneresis and shrinkage that the strips not fall out of the olive hole during storage. In the view point of marketing and nutritional aspects, it is more advantageous to develop a restructured fruit gel systems several times higher than the limiting 10% pulp because of its weak structure. Therefore, alginate-gel systems containing 25% pimiento pulp were evaluated at different levels of calcium chloride and thermal processing.

Adsorption of cadmium ions using the bioadsorbent of Pichia kudriavzevii YB5 immobilized by polyurethane foam and alginate gels.

Pichia kudriavzevii YB5, mutated from Pichia kudriavzevii A16 with a strong ability to remove cadmium ions, was immobilized by polyurethane foam and alginate gels in this work. The immobilization conditions were optimized as follows: sodium alginate concentration of 2% (w/v), calcium chloride concentration of 2% (w/v), biomass dose of 1 × 109 cell/mL, and cross-linking time for 4 h. Then, the results of batch adsorption experiments showed that the removal capacity of prepared bioadsorbent was significantly affected by the pH of media, contact time, and the initial Cd(II) concentration, and a suitable adsorption conditions of Cd(II) could be achieved with a pH value of 6.0 at 20 °C for 90 min. Kinetic and isothermal results indicated the behavior of Cd(II) adsorption onto immobilized P. kudriavzevii YB5 fitted to the pseudo-second-order kinetic equation and the Langmuir adsorption model. Thermodynamic results showed that the Cd(II) adsorption process was endothermic and spontaneous in nature. Besides, the Cd(II) removing capacity of the prepared bioadsorbent was also tested in the oyster hydrolysates, showing an average removal rate of 54.35%. Thus, the immobilized P. kudriavzevii YB5 adsorbent had great potential for application in aquatic products to ensure the food safety.

Embryonically inspired scaffolds regulate tenogenically differentiating cells.

Tendon injuries heal as scar tissue with significant dysfunction and propensity to re-injure, motivating efforts to develop stem cell-based therapies for tendon regeneration. For these therapies to succeed, effective cues to guide tenogenesis are needed. Our aim is to identify these cues within the embryonic tendon microenvironment. We recently demonstrated embryonic tendon elastic modulus increases during development and is substantially lower than in adult. Here, we examined how these embryonic mechanical properties influence tenogenically differentiating cells, by culturing embryonic tendon progenitor cells (TPCs) within alginate gel scaffolds fabricated with embryonic tendon mechanical properties. We showed that nano- and microscale moduli of RGD-functionalized alginate gels can be tailored to that of embryonic tendons by adjusting polymer concentration and crosslink density. These gels differentially regulated morphology of encapsulated TPCs as a function of initial elastic modulus. Additionally, higher initial elastic moduli elicited higher mRNA levels of scleraxis and collagen type XII but lower levels of collagen type I, whereas late tendon markers tenomodulin and collagen type III were unaffected. Our results demonstrate the potential to engineer scaffolds with embryonic mechanical properties and to use these scaffolds to regulate the behavior of tenogenically differentiating cells.

The role of poly-M and poly-GM sequences in the metal-mediated assembly of alginate gels.

Whilst the involvement of poly-G sequences in the formation of metal-mediated alginate gels has been previously studied in some detail, investigations into the role of poly-M and poly-GM sequences has been relatively neglected. In this regard, the binding of sodium and calcium ions to poly-M and poly-GM decamers, and their influence on chain aggregation, has been modelled by conducting a series of molecular dynamics simulations. This work complements a previous analogous study carried out for the poly-G decamer, whereby up to three strands are systematically introduced into each simulation. As in the previous study, this method allows intrinsic binding modes and interchain structural motifs to be revealed, that are consistent with those observed in available AFM images of consolidated 3-D networks. It is apparent from these studies that different sequences have different structural implications for metal-mediated chain association.

Comparison of selected physico-chemical properties of calcium alginate films prepared by two different methods.

Sodium alginate (SA) is a naturally occurring, non-toxic, polysaccharide that is able to form gels after exposure to calcium. These gels have been used in food and biomedical industries. This is the first direct comparison of two different methods of calcium alginate film production, namely interfacial gelation (IFG) and dry cast gelation (DCG). IFG films were significantly thicker than DCG films, and were more extensively rehydrated in water and 0.1M HCl than the DCG films. During rehydration in 0.1M HCl almost all calcium ions were lost. Under scanning electron microscopy, IFG films appeared less dense than DCG films. IFG films were mechanically weaker than DCG films, and both types of film were weaker after rehydration in 0.1M HCl compared with deionized water. Permeation of theophylline (TPL) was evaluated in-vitro; the diffusion coefficient (D) of the TPL was almost 90 times lower in DCG films than IFG films when both were rehydrated in water. Although the 0.1M HCl rendered both gels more permeable to TPL, D of TPL was still about five times lower in DCG compared to IFG films. The evaluation of selected physico-chemical properties of films is important, since this information may inform the choice of gelation technique used to produce calcium alginate coatings on pharmaceutical products.

Exploring the molecular basis for the metal-mediated assembly of alginate gels.

The binding of sodium and calcium ions to single and multiple poly-G decamer strands has been modelled by conducting a series of molecular dynamics simulations. Implications for metal mediated inter-strand interactions and gel assembly have been explored by systematically introducing up to three strands into each of these simulations. A particular emphasis has been placed on revealing intrinsic binding modes by an unbiased initial positioning of the metal ions. The results have revealed binding modes that provide a rationale for the observed gelling of alginate by calcium rather than sodium ions. A number of junction zones involving calcium ions have been identified that result in chain aggregation. This includes a distinctive perpendicular motif that appears to be ubiquitous in previously reported AFM images of open 3-D alginate networks. The coordination geometries of the metal ions have been characterised and the metal-mediated junctions between associated strands are described in detail.