pH Shock-promoted lysozyme corona for efficient pathogenic infections treatment: Effects of surface chemistry of mesoporous silica nanoparticles and loading method

Bifunctional lignocellulose nanofiber hydrogel possessing intriguing pH-responsiveness and self-healing capability towards wound healing applications

Lignocellulose nanofibers (LCNF) obtained from agricultural waste are potential candidates for enhancing composite materials because of their excellent mechanical properties, abundant groups and high biocompatibility. However, the application of LCNF has received limited attention to date from researchers in the healthcare field. Herein, based on the bifunctional group (carboxyl and aldehyde groups) modified LCNF (DCLCNF) and chitosan (CS), we developed a multifunctional bio-based hydrogel (CS-DCLCNF). The addition of lignin-containing DCLCNF strengthened the internal crosslinking and the intermolecular interaction of hydrogels, and the presence of lignin and carboxyl groups increased the mechanical strength of the hydrogel and the adsorption of aromatic drugs. Results revealed that the hydrogels exhibited self-healing, injectable, and high swelling rates. The hydrogels had favorable mechanical strength (G'max of ~16.60 kPa), and the maximum compressive stress was 24 kPa. Moreover, the entire tetracycline hydrochloride (TH) release process was slow and pH-responsive, because of the rich noncovalent and π-π interactions between DCLCNF and TH. The hydrogels also exhibited excellent biocompatibility and antibacterial properties. Notably, the wound healing experiment showed that the hydrogels were beneficial in accelerating wounds healing, which could heal completely in 13 days. Therefore, CS-DCLCNF hydrogels may have promising applications in drug delivery for wound healing.

Role of Clay Substrate Molecular Interactions in Some Dairy Technology Applications

The use of clay materials in dairy technology requires a multidisciplinary approach that allows correlating clay efficiency in the targeted application to its interactions with milk components. For profitability reasons, natural clays and clay minerals can be used as low-cost and harmless food-compatible materials for improving key processes such as fermentation and coagulation. Under chemical stability conditions, clay materials can act as adsorbents, since anionic clay minerals such as hydrotalcite already showed effectiveness in the continuous removal of lactic acid via in situ anion exchange during fermentation and ex situ regeneration by ozone. Raw and modified bentonites and smectites have also been used as adsorbents in aflatoxin retention and as acidic species in milk acidification and coagulation. Aflatoxins and organophilic milk components, particularly non-charged caseins around their isoelectric points, are expected to display high affinity towards high silica regions on the clay surface. Here, clay interactions with milk components are key factors that govern adsorption and surface physicochemical processes. Knowledge about these interactions and changes in clay behavior according to the pH and chemical composition of the liquid media and, more importantly, clay chemical stability is an essential requirement for understanding process improvements in dairy technology, both upstream and downstream of milk production. The present paper provides a comprehensive review with deep analysis and synthesis of the main findings of studies in this area. This may be greatly useful for mastering milk processing efficiency and envisaging new prospects in dairy technology.

Optimization and scale-up of Clostridium perfringens type D culture and epsilon-toxin production: Effects of stirring, glucose and pH adjustment

The effects of some main bacteria culture parameters including mixing rate, glucose (GC) concentration, steps of GC addition, and steps of pH adjustment on both C. perfringens bacteria growth and its epsilon toxin production in a bench-scale 20-L glass carboy were investigated. The optimized mixing rate of 300 rpm, GC concentration of 4 g L-1, and 3-step addition of GC resulted in the bacteria and toxin concentrations of 0.16 g L-1 and 330 ng mL-1, respectively. Also, the induction of a pH shock at the reaction time of 180 min led to the remarkable enhancement of toxin production (367 ng mL-1). Upon applying both optimized conditions for GC addition and pH adjustment, the high toxin concentration of 433 ng mL-1 was obtained. Using the constant mixing rate technique, the process was scaled up to a 1500-L industrial bioreactor, where its performance was close to the bench-scale bioreactor (i.e., toxin concentration of 419 ng mL-1). The results revealed the reliability of this method to economically improve and scale up the bacteria culture process, which can be further used for other microbial fermentations.

Effect of the Structure of Magnetic Nanocomposite Adsorbents on the Lysozyme Separation Efficiency

In this study, we prepared various anionic magnetic adsorbents through the carboxyl functionalization of core/shell-structured Fe₃O₄/SiO₂ (FS) particles by either succinic anhydride (FSC), low-molecular-weight (MW 1800) polyacrylic acid (PAA) (FSP1), or high-molecular-weight (MW 100,000) PAA (FSP2), and then, investigated the effect of the structure of adsorbents and operational parameters on their performance for the lysozyme separation. The type and size of functional molecules have significant effects on the surface concentration of functional carboxyl groups onto the adsorbent particles (increase in the order of FSP2 > FSP1 > FSC), and consequently on the adsorption efficiency (AE) (∼100, 98, and 62%, respectively) and adsorption capacity (AC) (∼1000, 980, and 621 mg·g^-1, respectively) of the adsorbents. However, the loss of the antibacterial activity of separated lysozyme molecules due to the molecular conformational change increased in the order of FSP2 > FSP1 = FSC, as compared to the free lysozyme. The application of basic buffer solutions for the elution of adsorbed enzyme molecules resulted in more adverse effects on the enzyme activity. The obtained results recommend that FSP1 can be used as a suitable anionic adsorbent for the isolation of positively charged proteins, owing to its high adsorption capacity, excellent reusability, and structural stability, as well as the high purity, structural stability, and activity recovery of the isolated proteins.