Development of a biocomposite based on alginate/gelatin crosslinked with genipin for β-galactosidase immobilization: Performance and characteristics

Hydrolysis of Casein by Pepsin Immobilized on Heterofunctional Supports to Produce Antioxidant Peptides

A study was carried out on the immobilization of pepsin in activated carbon functionalized by different techniques (glutaraldehyde, genipin, and metallization) aiming at its application in obtaining bioactive peptides through casein hydrolysis. Studies of the immobilized derivatives were carried out in addition to the evaluation of the antioxidant potential of the peptides. Among the pH range studied, pH 3.0 was selected due to the higher activity of the derivatives at this pH. The support modification by metallization was the method with the best results, providing a 121% increase in enzymatic activity compared to other immobilization methods. In addition, this derivative provided activity closer to the soluble enzyme activity (3.30 U) and better storage stability, and allows reuse for more than 8 cycles. In turn, the peptides from casein hydrolysis showed potential as antioxidant agents, with a DPPH radical scavenging activity higher than 70%, maximum protection against β-carotene oxidation close to 70%, and a maximum reducing power of Fe(III) into Fe(II) of 400 uM by the FRAP assay. The results showed that the new techniques for modification of activated carbon can be a promising approach for pepsin immobilization.

Design of an antioxidant powder additive based on carvacrol encapsulated into a multilayer chitosan-alginate-maltodextrin emulsion

Carvacrol has demonstrated antioxidant activity; however, its high volatility and low water solubility limit its direct application in food matrices. Then, an effective encapsulation system is required to protect it. This study aimed to design and characterize a carvacrol-based additive encapsulated in a spray-dried multilayer emulsion based on chitosan/sodium alginate/maltodextrin. Spray-drying temperature of 120 °C and 3 %(w/w) maltodextrin content maximized both encapsulation efficiency (~97 %) and loading capacity (~53 %). The powder's antioxidant properties were evaluated in two food simulant media: water (SiW) and water-ethanol (SiD). The highest antioxidant activity was observed in SiW for both ABTS•+ (8.2 ± 0.3mgEAG/g) and FRAP (4.1 ± 0.2mgEAG/g) methods because of the reduced release of carvacrol in SiD vs. SiW, as supported by micro- and macrostructural observations by SAXS and microscopy, respectively. An increase from 143 to 157 °C attributable to carvacrol protection and Tg = 44.4 °C (> ambient) were obtained by TGA and DSC, respectively. FT-IR confirmed intermolecular interactions (e.g. -COO- and -NH3+) as well as H-bonding formation. High water solubility (81 ± 3 %), low hygroscopicity (8.8 ± 0.2 %(w/w), poor flowability (CI:45 ± 4), and high cohesiveness (HR:1.8 ± 0.1) between particles were achieved, leading to a powdered antioxidant additive with high potential for applications which required avoiding/reducing oxidation on hydrophilic and hydrophobic food products.

Grafted calcium pectinate-whey protein isolate covalent immobilizers: Optimization, kinetics, thermodynamics, and application

Whey protein isolate (WPI) was incorporated within calcium pectinate (CPT) beads in order to boost their anionic qualities and meliorate their glutaraldehyde (GA)-polyethyleneimine (PEI) grafting process. The Box-Behnken Design (BBD) verified that WPI inclusion significantly raised the GA-PEI-CPT-WPI beads immobilized β-D-galactosidase (iβ-GLD) activity. The BBD also revealed the optimal settings for WPI concentration, PEI pH, PEI concentration, and GA concentration, which were 2.91 %, 10.8, 3.5 %, and 2.24 %, respectively. The GA-PEI-CPT-WPI beads grafting process was scrutinized via FTIR, EDX, and SEM. The optimal GA-PEI-CPT-WPI immobilizers provided fine β-GLD immobilization efficiencies, which reached up to 65.28 %. The free and GA-PEI-CPT-WPI iβ-GLDs pH and temperature profiles were scrutinized. It was also unveiled that the thermal stability of the iβ-GLD surpassed that of its free compeer as it provided lesser kd and ΔS values and larger t1/2, D-values, Ed, ΔH, and ΔG values. Furthermore, the iβ-GLD provided 92.00±3.39 % activity after 42 storage days, which denoted its fine storage stability. The iβ-GLD short duration (15 min) operational stability was also inspected, and 82.70±0.78 % activity was provided during the fifteenth degradation run. Moreover, the iβ-GLD long duration (24 h) operational stability was inspected while degrading the lactose of buffered lactose solution (BLS) and cheese whey (CW). It was unveiled that 81.86±0.96 % and 73.58±2.24 % of the initial glucose were detected during the sixth degradation runs, respectively.

Aspergillus oryzae β-D-galactosidase immobilization on glutaraldehyde pre-activated amino-functionalized magnetic mesoporous silica: Performance, characteristics, and application in the preparation of sesaminol

Aspergillus oryzae β-D-galactosidase (β-Gal) efficiently hydrolyzes sesaminol triglucoside into sesaminol, which has higher biological activity. However, β-Gal is difficult to be separate from the reaction mixture and limited by stability. To resolve these problems, β-Gal was immobilized on amino-functionalized magnetic nanoparticles mesoporous silica pre-activated with glutaraldehyde (Fe3O4@mSiO2-β-Gal), which was used for the first time to prepare sesaminol. Under the optimal conditions, the immobilization yield and recovered activity of β-Gal were 57.9 ± 0.3 % and 46.5 ± 0.9 %, and the enzymatic loading was 843 ± 21 Uenzyme/gsupport. The construction of Fe3O4@mSiO2-β-Gal was confirmed by various characterization methods, and the results indicated it was suitable for heterogeneous enzyme-catalyzed reactions. Fe3O4@mSiO2-β-Gal was readily separable under magnetic action and displayed improved activity in extreme pH and temperature conditions. After 45 days of storage at 4 °C, the activity of Fe3O4@mSiO2-β-Gal remained at 92.3 ± 2.8 %, which was 1.29 times than that of free enzyme, and its activity remained above 85 % after 10 cycles. Fe3O4@mSiO2-β-Gal displayed higher affinity and catalytic efficiency. The half-life was 1.41 longer than free enzymes at 55.0 °C. Fe3O4@mSiO2-β-Gal was employed as a catalyst to prepare sesaminol, achieving a 96.7 % conversion yield of sesaminol. The excellent stability and catalytic efficiency provide broad benefits and potential for biocatalytic industry applications.

Multicomponent Synergistic Antibacterial Hydrogel Based on Gelatin-Oxidized Carboxymethyl Cellulose for Wound Healing of Drug-Resistant Chronic Infection

Bacterial invasion hinders the healing process of wound, leading to the formation of chronic infected wound; meanwhile, the misuse of antibiotics has resulted in the emergence of numerous drug-resistant bacteria. The application of conventional antimicrobial methods and wound treatment techniques is not appropriate for wound dressings. In this paper, quaternized poly(vinyl alcohol) (QPVA) and pomegranate-like copper uniformly doped polydopamine nanoparticles (PDA@Cu) were introduced into a gelatin-oxidized carboxymethyl cellulose system to form a multicomponent synergistic antibacterial hydrogel (GOQ3P3). Polydopamine improves the biocompatibility and prevents the detachment of Cu nanoparticles. It can achieve synergistic antibacterial effects through quaternary ammonium salt-inorganic nanoparticle photothermal treatment under 808 nm near-infrared (NIR) irradiation. It exhibits highly efficient and rapid bactericidal properties against Escherichia coli, Staphylococcus aureus, and MRSA (methicillin-resistant Staphylococcus aureus) with an antibacterial rate close to 100%. The gel scaffold composed of macromolecules gives the hydrogel excellent mechanical properties, adhesive capabilities, self-healing characteristics, biocompatibility, and pH degradation and promotes cell adhesion and migration. In a full-thickness wound healing model infected with MRSA, GOQ3P3 controls inflammatory responses, accelerates collagen deposition, promotes angiogenesis, and enhances wound closure in the wound healing cascade reaction. This study provides a feasible strategy for constructing dressings targeting chronic infection wounds caused by drug-resistant bacteria.

Lactose hydrolysis in packed-and fluidized-bed reactors using a recombinant β-galactosidase immobilized on magnetic core-shell capsules

The objective of this study was to develop a bioprocess for lactose hydrolysis in diverse dairy matrices, specifically skim milk and cheese whey, utilizing column reactors employing a core-shell enzymatic system featuring β-galactosidase fused to a Cellulose Binding Domain (CBD) tag (β-galactosidase-CBD). The effectiveness of reactor configurations, including ball columns and toothed columns operating in packed and fluidized-bed modes, was evaluated for catalyzing lactose hydrolysis in both skim milk and cheese whey. In a closed system, these reactors achieved lactose hydrolysis rates of approximately 50% within 5 h under all evaluated conditions. Considering the scale of the bioprocess, the developed enzymatic system was capable of continuously hydrolyzing 9.6 L of skim milk while maintaining relative hydrolysis levels of approximately 50%. The biocatalyst, created by immobilizing β-galactosidase-CBD on magnetic core-shell capsules, exhibited exceptional operational stability, and the proposed bioprocess employing these column reactors showcases the potential for scalability.

Microcin C7-laden modified gelatin based biocomposite hydrogel for the treatment of periodontitis

Periodontitis is an oral disease with the highest incidence globally, and plaque control is the key to its treatment. In this study, Microcin C7 was used to treat periodontitis, and a novel injectable temperature-sensitive sustained-release hydrogel was synthesized as an environmentally sensitive carrier for drug delivery. First, modified gelatin was formed from gelatin and glycidyl methacrylate. Then, Microcin C7-laden hydrogel was formed from cross-linking with double bonds between modified gelatin, N-isopropyl acrylamide, and 2-Methacryloyloxyethyl phosphorylcholine through radical polymerization, and the model drug Microcin C7 was loaded by electrostatic adsorption. The hydrogel has good temperature sensitivity, self-healing, and injectable properties. In vitro results showed that the hydrogel could slowly and continuously release Microcin C7 with good biocompatibility and biodegradability, with a remarkable antibacterial effect on Porphyromonas gingivalis. It also confirmed the antibacterial and anti-inflammatory effects of Microcin C7-laden hydrogel in a periodontitis rat model. The results showed that Microcin C7-laden hydrogel is a promising candidate for local drug delivery systems in periodontitis.

Enzymes Immobilized into Starch- and Gelatin-Based Hydrogels: Properties and Application in Inhibition Assay

The present work is a review of the research on using hydrogels based on natural biodegradable polymers, starch, and gelatin for enzyme immobilization. This review addresses the main properties of starch and gelatin that make them promising materials in biotechnology for producing enzyme preparations stable during use and storage and insensitive to chemical and physical impacts. The authors summarize their achievements in developing the preparations of enzymes immobilized in starch and gelatin gels and assess their activity, stability, and sensitivity for use as biorecognition elements of enzyme inhibition-based biosensors.

Investigating the Interplay Between Matrix Compliance and Passaging History on Chondrogenic Differentiation of Mesenchymal Stem Cells Encapsulated Within Alginate-Gelatin Hybrid Hydrogels

Mesenchymal stem cells (MSCs) are used widely in tissue engineering and regenerative medicine because of their ease of isolation and their pluripotency. The low survival and retention rate of MSCs at the target site upon implantation can be addressed via encapsulation within hydrogels capable of directing their fate. In this study, the interplay between matrix mechanics and the passage number of MSCs on their chondrogenic differentiation was assessed. Human bone marrow-derived MSCs between passages 4 and 6 were encapsulated within alginate-gelatin hybrid gels. The stiffness of the gels was varied by varying alginate concentrations while maintaining the concentration of gelatin and consequently, the cell adhesion sites, constant. The study revealed that within 4.8 kPa gels, GAG deposition was higher by P4 MSCs compared to P6 MSCs. However, an opposite trend was observed with collagen type 2 deposition. Further, we observed enhanced chondrogenic differentiation upon encapsulation of MSCs within 6.7 kPa hydrogel irrespective of passaging history. However, the effect of matrix compliance was more prominent in the case of higher passaged MSCs suggesting that matrix stiffness can help rescue the reduced differentiation capability of these cells.

Detection of insecticides by Tetronarce californica acetylcholinesterase via expression and in silico analysis

The acetylcholinesterase (AChE) is involved in termination of synaptic transmission at cholinergic synapses and plays a vital role in the insecticide detection and inhibitor screening. Here, we report the heterologous expression of an AChE from Tetronarce californica (TcA) in Escherichia coli (E. coli) as a soluble active protein. TcA was immobilized in calcium alginate beads; the morphology, biochemical properties, and insecticide detection performance of free and immobilized TcA were characterized. Moreover, we used sequence, structure-based approaches, and molecular docking to investigate structural and functional characterization of TcA. The results showed that TcA exhibited a specific activity of 102 U/mg, with optimal activity at pH 8.0 and 30 °C. Immobilized TcA demonstrated superior thermal stability, pH stability, and storage stability compared to the free enzyme. The highest sensitivity of free TcA was observed with trichlorfon, whereas immobilized TcA showed reduced IC50 values towards tested insecticides by 3 to 180-fold. Molecular docking analysis revealed the interaction of trichlorfon, acephate, isoprocarb, λ-cyhalothrin, and fenpropathrin in the active site gorge of TcA, particularly mediated through the formation of hydrogen bonds and π-π stacking. Therefore, TcA expressed heterologously in E. coli is a promising candidate for applications in food safety and environmental analysis. KEY POINTS: • T. californica AChE was expressed solubly in prokaryotic system. • The biochemical properties of free/immobilized enzyme were characterized. • The sensitivity of enzyme to insecticides was evaluated in vitro and in silico.

Genipin crosslinked porous chitosan beads as robust supports for β-galactosidase immobilization: Characterization, stability, and bioprocessing potential

This study aimed to modify the porosity of chitosan beads using Na2CO3 as a porogen agent and to crosslink them with genipin for the immobilization of β-galactosidase from Aspergillus oryzae. Immobilization was performed under four different pH conditions (4.5, 6.0, 7.5, and 9.0), resulting in biocatalysts named B4, B6, B7, and B9, respectively. The immobilized enzymes were characterized for immobilization parameters and stability, including thermal, pH, storage, and operational stability. The optimal conditions for the support were determined as 50 mM Na2CO3. The biocatalyst exhibited nearly 100 % retention of initial activity after 5 h of incubation at different pH conditions and showed improved thermal stability compared to the free enzyme across all pH conditions. After 50 cycles of lactose hydrolysis, all biocatalysts retained at least 71 % of their initial activity, with B6 retaining nearly 100 %. Scanning electron microscopy revealed structural modifications, particularly in B4, leading to weakened support structure after reuse. Continuous lactose hydrolysis showed increased productivity from 41.3 to 48.1 g L-1 h-1 for B6, with 78.1 % retention of initial capacity. All biocatalysts retained >95 % activity when stored at 4 °C for 20 weeks, highlighting their suitability for enzyme immobilization in continuous and discontinuous bioprocesses.

Immobilization of commercial horseradish peroxidase in calcium alginate-starch hybrid support and its application in the biodegradation of phenol red dye

In this study, horseradish peroxidase (HRP) was immobilized for the first time on Ca alginate-starch hybrid beads and employed for the biodegradation of phenol red dye. The optimal protein loading was 50 mg/g of support. Immobilized HRP demonstrated improved thermal stability and maximum catalytic activity at 50 °C and pH 6.0, with an increase in half-life (t1/2) and enzymatic deactivation energy (Ed) compared to free HRP. After 30 days of storage at 4 °C, immobilized HRP retained 109% of its initial activity. Compared to free HRP, the immobilized enzyme exhibited higher potential for phenol red dye degradation, as evidenced by the removal of 55.87% of initial phenol red after 90 min, which was 11.5 times greater than free HRP. In sequential batch reactions, the immobilized HRP demonstrated good potential efficiency for the biodegradation of phenol red dye. The immobilized HRP was used for a total of 15 cycles, degrading 18.99% after 10 cycles and 11.69% after 15 cycles, with a residual enzymatic activity of 19.40% and 12.34%, respectively. Overall, the results suggest that HRP immobilized on Ca alginate-starch hybrid supports shows promise as a biocatalyst for industrial and biotechnological applications, particularly for the biodegradation of recalcitrant compounds such as phenol red dye.

Glutaraldehyde-pea protein grafted polysaccharide matrices for functioning as covalent immobilizers

Three polysaccharide matrices (κ-Carrageenan (Carr), gellan gum, and agar) were grafted via glutaraldehyde (GA) and pea protein (PP). The grafted matrices covalently immobilized β-D-galactosidase (β-GL). Nonetheless, grafted Carr acquired the topmost amount of immobilized β-GL (iβ-GL). Thus, its grafting process was honed via Box-Behnken design and was further characterized via FTIR, EDX, and SEM. The optimal GA-PP-Carr grafting comprised processing Carr beads with 10% PP dispersion of pH 1 and 25% GA solution. The optimal GA-PP-Carr beads acquired 11.44 Ug^-1 iβ-GL with 45.49% immobilization efficiency. Both free and GA-PP-Carr iβ-GLs manifested their topmost activity at the selfsame temperature and pH. Nonetheless, the β-GL K_m and V_max values were reduced following immobilization. The GA-PP-Carr iβ-GL manifested good operational stability. Moreover, its storage stability was incremented where 91.74% activity was offered after 35 storage days. The GA-PP-Carr iβ-GL was utilized to degrade lactose in whey permeate with 81.90% lactose degradation efficiency.

Responsive and biocompatible chitosan-phytate microparticles with various morphology for antibacterial activity based on gas-shearing microfluidics

Chitosan microparticles are frequently used for the encapsulation of ingredients, owing to their pH-responsive, renewable, biocompatible and antimicrobial properties. Herein, pH-responsive antibacterial encapsulation carriers in chitosan-phytate (CS-PA) microparticles with various morphologies were prepared by gas-shearing microfluidics. Microparticles sizes were tuned by gas flow rate in production, and the CS and PA concentration significantly dominated the morphology of microparticles. Additionally, microparticles exhibit great storage stability, lyophilizing rehydration performance, pH-responsive behavior, as well as antibacterial and biocompatible effect, indicating that CS-PA microparticles are expected to become an ideal carrier for the actives encapsulation in pharmaceutical, food and cosmetic industries.

Self-assembled emulsion gel based on modified chitosan and gelatin: Anti-inflammatory and improving cellular uptake of lipid-soluble actives

To obtain a green carrier for intestinal targeted delivery, an emulsion gel was designed by the self-assembly between gelatin and Pickering emulsion based on gallic acid modified-chitosan nanoparticles (GCS NPs). The emulsion gels loaded with garlic essential oil (Geo) and curcumin (Cur) were abbreviated as GOEG and GCEG, respectively. Meanwhile, the sodium alginate bead loaded with Geo (GOEGS₃) and the bead loaded with Cur (GCEGS) were prepared as controls. Results demonstrated that the emulsion gels significantly improved the bioaccessibility of Geo and Cur, showing great intestinal targeting delivery properties comparable to that of sodium alginate beads. Moreover, Caco-2 cell experiments indicated that GOEG and GCEG displayed good biocompatibility and enhanced cellular uptake of Geo and Cur. The emulsion gels also exhibited excellent anti-inflammatory properties in the lipopolysaccharide-induced cell model, exhibiting great potential for clinical application. This work provides some references for the preparation of multifunctional emulsion gels with excellent delivery performance by a green method.