Lysozyme distribution, structural identification, and in vitro release of starch-based microgel-lysozyme complexes

A Structural Study on Absorption of Lysozyme in Amorphous Starch Microspheres

The potential of using proteins as drugs is held back by their low stability in the human body and challenge of delivering them to the site of function. Extensive research is focused on drug delivery systems that can protect, carry, and release proteins in a controlled manner. Of high potential are cross-linked degradable starch microspheres (DSMs), as production of these is low-cost and environmentally friendly, and the products are degradable by the human body. Here, we demonstrate that DSMs can absorb the model protein lysozyme from an aqueous solution. At low amounts of lysozyme, its concentration in starch microspheres strongly exceeds the bulk concentration in water. However, at higher protein contents, the difference between concentrations in the two phases becomes small. This indicates that, at lower lysozyme contents, the absorption is driven by protein-starch interactions, which are counteracted by protein-protein electrostatic repulsion at high concentrations. By applying small-angle X-ray scattering (SAXS) to the DSM-lysozyme system, we show that lysozyme molecules are largely unaltered by the absorption in DSM. In the same process, the starch network is slightly perturbed, as demonstrated by a decrease in the characteristic chain to chain distance. The SAXS data modeling suggests an uneven distribution of the protein within the DSM particles, which can be dependent on the internal DSM structure and on the physical interactions between the components. The results presented here show that lysozyme can be incorporated into degradable starch microspheres without any dependence on electrostatic or specific interactions, suggesting that similar absorption would be possible for pharmaceutical proteins.

Impact of Esterification with Octenyl Succinic Anhydride on the Structural Characteristics and Glucose Response in Mice of Wheat Starch

In this study, we investigated the structural properties and digestibility of wheat starch treated with octenyl succinic anhydride (OSA). For the experiment, the samples were reacted with 2, 4, 6, 8, and 10% OSA (pH 8.5-9.0) for 2 h. A light micrograph showed that there was no difference in the morphology and Maltese cross between native and OSA-treated starch. The X-ray diffraction (XRD) patterns of the native and OSA-treated starches showed typical A-type diffraction. In addition, the Fourier transform infrared (FT-IR) spectrum showed a distinct carbonyl peak at approximately 1730 cm-1, indicating the stretching vibration of the C=O bond of the ester group. The degree of substitution (DS) and content of resistant starch (RS) increased with increasing concentrations of treated OSA because of the increase in ester bonds. In particular, RS was thermostable compared to the RS content in uncooked and cooked starch. Blood glucose levels and response in vivo decreased as the OSA concentration increased. Treatment of wheat starch with 8% OSA concentration produced 35.6% heat-stable resistant starch. These results suggest that starch modified with OSA can be used to produce functional foods for diabetes.

Elucidating the Molecular Interactions between Lipids and Lysozyme: Evaporation Resistance and Bacterial Barriers for Dry Eye Disease

Dry eye disease (DED) is a chronic condition characterized by ocular dryness and inflammation. The tear film lipid layer (TFLL) is the outermost layer composed of lipids and proteins that protect the ocular surface. However, environmental contaminants can disrupt its structure, potentially leading to DED. Although the importance of tear proteins in the TFLL functionality has been clinically recognized, the molecular mechanisms underlying TFLL-protein interactions remain unclear. In this study, we investigated tear protein-lipid interactions and analyzed their role in the TFLL functionality. The results show that lysozyme (LYZ) increases the stability of the TFLL by reducing its surface tension and increasing its surface pressure, resulting in increased TFLL evaporation and bacterial invasion resistance, with improved wettability and lubrication performance. These findings highlight the critical role of LYZ in maintaining ocular health and provide potential avenues for investigating novel approaches to DED treatment and patient well-being.

Recent Advances in Sustainable Antimicrobial Food Packaging: Insights into Release Mechanisms, Design Strategies, and Applications in the Food Industry

In response to the issues of foodborne microbial contamination and carbon neutrality goals, sustainable antimicrobial food packaging (SAFP) composed of renewable or biodegradable biopolymer matrices with ecofriendly antimicrobial agents has emerged. SAFP offers longer effectiveness, wider coverage, more controllability, and better environmental performance. Analyzing SAFP information, including the release profile of each antimicrobial agent for each food, the interaction of each biomass matrix with each food, the material size, form, and preparation methods, and its service quality in real foods, is crucial. While encouraging reports exist, a comprehensive review summarizing these developments is lacking. Therefore, this review critically examines recent release-antimicrobial mechanisms, kinetics models, preparation methods, and key regulatory parameters for SAFPs based on slow- or controlled-release theory. Furthermore, it discusses fundamental physicochemical characteristics, effective concentrations, advantages, release approaches, and antimicrobial and preservative effects of various materials in food simulants or actual food. Lastly, inadequacies and future trends are explored, providing practical references to regulate the movement of active substances in different media, reduce the reliance on petrochemical-based materials, and advance food packaging and preservation technologies.

Long-term antibacterial activity by synergistic release of biosafe lysozyme and chitosan from LBL-structured nanofibers

Biosafe antibacterial agents are urgently demanded in treating infection especially chronic infection. However, efficient and controlled release of those agents remains great challenging. Two nature-derived agents, lysozyme (LY) and chitosan (CS), are selected to establish a facile method for long-term bacterial inhibition. We incorporated LY into the nanofibrous mats, then deposited CS and polydopamine (PDA) on the surface by layer-by-layer (LBL) self-assembly. In this vein, LY is gradually released with the degradation of nanofibers, and CS is rapidly disassociated from the nanofibrous mats to synergistically result in a potent inhibition against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) over a period of 14 days. Besides long-term antibacterial capacity, LBL-structured mats could readily achieve a strong tensile stress of 6.7 MPa with an increase percentage of up to 103%. The enhanced proliferation of L929 cells arrives at 94% with help of CS and PDA on the surface of nanofibers. In this vein, our nanofiber has a variety of advantages including biocompatibility, strong long-term antibacterial effect, and skin adaptability, revealing the significant potential to be used as highly safe biomaterial for wound dressings.

Fabrication of lipase-loaded particles by coacervation with chitosan

Coacervation of the lipase from Aspergillus oryzae (AOL) with chitosan was a feasible way to fabricate lipase-loaded particles and the optimum conditions were phase separation pH 5.5, chitosan to AOL mass ratio 1:5, and temperature 25 °C in the absence of NaCl, which conferred an AOL loading efficiency of up to 95.48% and activity recovery of 69.60%. The AOL-chitosan coacervates were highly porous and more susceptible to weight loss upon heating. Coacervation with chitosan increased the activity of AOL and shifted its optimum pH from 7.0 to 6.0, but exerted no effect on its optimum temperature (45 °C). Thermal deactivation kinetics analysis revealed that the coacervated AOL was more thermal stable, while the Michaelis-Menten kinetics analysis indicated that coacervation with chitosan increased the V_max of AOL by 2.4 folds, but decreased its substrate affinity by 3.6 folds. Hence, the AOL-chitosan coacervates are potential in the construction of Pickering emulsion-based lipase catalysis systems.

Interaction of Carrier Protein with Potential Metallic Drug Candidate N-Glycoside 'GATPT': Validation by Multi-Spectroscopic and Molecular Docking Approaches

Lysozyme is often used as a model protein to study interaction with drug molecules and to understand biological processes which help in illuminating the therapeutic effectiveness of the drug. In the present work, in vitro interaction studies of 1-{(2-hydroxyethyl)amino}-2-amino-1,2-dideoxy-d-glucose triphenyl tin (IV) (GATPT) complex with lysozyme were carried out by employing various biophysical methods such as absorption, fluorescence, and circular dichroism (CD) spectroscopies. The experimental results revealed efficient binding affinity of GATPT with lysozyme with intrinsic binding (Kb) and binding constant (K) values in the order of 105 M-1. The number of binding sites and thermodynamic parameters ΔG, ΔH, and ΔS at four different temperatures were also calculated and the interaction of GATPT with lysozyme was found to be enthalpy and entropy driven. The CD spectra revealed alterations in the population of α-helical content within the secondary structure of lysozyme in presence of GATPT complex. The morphological analysis of the complex with lysozyme and lysozyme-DNA condensates was carried out by employing confocal and SEM studies. Furthermore, the molecular docking studies confirmed the interaction of GATPT within the larger hydrophobic pocket of the lysozyme via several non-covalent interactions.

Lysozyme-like Protein Produced by Bifidobacterium longum Regulates Human Gut Microbiota Using In Vitro Models

The extracellular secreted protein of Bifidobacterium longum (B. longum) plays an important role in maintaining the homeostasis of the human intestinal microenvironment. However, the mechanism(s) of interaction remain unclear. Lysozyme is a kind of antibacterial peptide. In this study, the amino acid sequence of a lysozyme-like protein of B. longum based on whole-genome data of an isolate from human gut feces was found. We further predicted functional domains from the amino acid sequence, purified the protein, and verified its bioactivity. The growth of some bacteria were significantly delayed by the 020402_LYZ M1 protein. In addition, the gut microbiota was analyzed via high-throughput sequencing of 16S rRNA genes and an in vitro fermentation model, and the fluctuations in the gut microbiota under the treatment of 020402_LYZ M1 protein were characterized. The 020402_LYZ M1 protein affected the composition of human gut microbiota significantly, implying that the protein is able to communicate with intestinal microbes as a regulatory factor.

Evaluation of Utilizing Functionalized Graphene Oxide Nanoribbons as Compatible Biomaterial for Lysozyme

Graphene oxide nanoribbons with superior physicochemical properties acquired from graphene and carbon nanotubes have been used in various applications including biomedical applications. For biomedical applications, it is of utmost importance to understand how these graphene oxide nanoribbons interact with proteins and the influence they have on protein conformation and function. In this regard, an attempt has been made to evaluate the utility of graphene oxide nanoribbons as a compatible biomaterial for lysozyme (Lys) protein. In this study, graphene oxide nanoribbons (GONRs) synthesized from multiwalled carbon nanotubes (MWCNTs) were first functionalized with (3-aminopropyl)triethoxysilane (APTES) and further modified with vanillin (Val) to obtain Val-APTES-GONRs. On characterization, it was found that the Val-APTES-GONRs material had a ribbonlike morphology with abundant functionalities for interaction with protein. On evaluation of Val-APTES-GONRs as a compatible biomaterial for Lys, studies revealed that a lower concentration of the as-synthesized material has less influence on the conformation and the structure of Lys with better activity, whereas higher concentrations of the as-synthesized material had a greater influence on conformation and the structure of Lys with decreased activity. Overall, the thermal stability of Lys was maintained after introducing the Val-APTES-GONRs material. In addition, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) and Raman spectroscopies were performed for Lys composites with Val-APTES-GONRs for further understanding biomolecular interactions. This study is beneficial for designing advanced graphene-based materials for numerous bioinspired applications and better biomaterials for biotechnological use.

Poly(glycidyl methacrylate) macromolecular assemblies as biocompatible nanocarrier for the antimicrobial lysozyme

The antimicrobial lysozyme (Lys) was electrostatically incorporated to negatively charged crosslinked poly(glycidyl methacrylate) (c-PGMA) macromolecular assemblies. The resulting material was characterized by AFM, infrared spectra, water contact angle measurements and the staining with the primary amino specific dye fluorescamine. c-PGMA nanoparticles were successfully loaded with Lys reaching ratios of 27.3 ± 4.0 and 22.5 ± 1.7 mg Lys/g polymer for c-PGMA suspensions and functionalized glass substrates, respectively. Lys-loaded c-PGMA caused clear inhibition zones on S. aureus and E. coli in comparison to neat c-PGMA. c-PGMA functionalized surfaces were intrinsically resistant to colonization, but the incorporation of Lys added resistance to bacterial attachment and allowed keeping surfaces clean of bacterial cells for both strains. A relatively rapid release (24 h) of Lys was observed at physiological pH (7.4). In addition, c-PGMA functionalized substrates could be reloaded several times without losing capacity. c-PGMA macromolecular assemblies did not display cytotoxicity to human dermal fibroblasts as shown in 24 h MTT assays. This work demonstrated that c-PGMA assemblies display durable antibacterial activity, biocompatibility, and full reloading capacity with antimicrobial peptides. c-PGMA functionalized materials have potential application as nanocarriers for anti-infective uses.

Mechanochemical Formation of Protein Nanofibril: Graphene Nanoplatelet Hybrids and Their Thermoelectric Properties

Hybrids between biopolymeric materials and low-cost conductive carbon-based materials are interesting materials for applications in electronics, potentially reducing the need for materials that generate environmentally harmful electronic waste. Herein we investigate a scalable ball-milling method to form graphene nanoplatelets (GNPs) by milling graphite flakes with aqueous dispersions of proteins or protein nanofibrils (PNFs). Aqueous GNP dispersions with high concentrations (up to 3.2 mg mL^-1) are obtained under appropriate conditions. The PNFs/proteins help to exfoliate graphite and stabilize the resulting GNP dispersions by electrostatic repulsion. PNFs are prepared from hen egg white lysozyme (HEWL) and β-lactoglobulin (BLG). The GNP dispersions can be processed into free-standing films having an electrical conductivity of up to 110 S m^-1. Alternatively, the GNP dispersions can be drop-cast on PET substrates, resulting in mechanically flexible films having an electrical conductivity of up to 65 S m^-1. The drop-cast films are investigated regarding their thermoelectric properties, having Seebeck coefficients of about 50 μV K^-1. By annealing drop-cast films and thus carbonizing residual PNFs, an increase of electrical conductivity, coupled with a modest decrease in Seebeck coefficient, is obtained resulting in materials displaying power factors of up to 4.6 μW m^-1 K^-2.

Sustainable Solvothermal Conversion of Waste Biomass to Functional Carbon Material: Extending Its Utility as a Biocompatible Cosolvent for Lysozyme

Functional carbon material synthesis from waste biomass by a sustainable method is of prime importance and has wide variety of applications. Herein, functional carbon materials with structural variability are synthesized using a well-known solvothermal method. The leftover pulp waste biomass (PB) of citrus limetta is converted to functional carbon by treatment with a mixture of choline bitartrate (ChBt) and FeCl₃ (1:2 mol ratio) as a solvent. The biomass to solvent ratio is varied as 1:1, 0.8:1, and 0.4:1 during solvothermal treatment to obtain PB-1, PB-2, and PB-3 as functional carbon materials, respectively. On characterization, PB carbon materials were found to be rich in oxygen-containing functional groups possessing different morphologies. Furthermore, results suggested the role of solvent as a soft template and catalyst during the synthesis of carbon materials. The feasibility of synthesized carbon materials as a biocompatible cosolvent for lysozyme was evaluated. In the case of PB-2 material (synthesized using 0.8:1 biomass to solvent ratio), results show an enhancement of lysozyme activity by 150%. Besides, spectroscopic and calorimetric data confirm the preservation of thermal and structural stability of lysozyme in the PB-2 solution. Thus, this study stipulates PB-2 as an excellent cosolvent for protein studies. With this work, we aim to delve into an entirely new arena of applications of biomass in the field of biotechnology.

Lysozyme/collagen multilayers layer-by-layer deposited nanofibers with enhanced biocompatibility and antibacterial activity

Biological meshes have always posed a challenge in biological medicine, for which nanocomposites with enhanced biocompatibility and antibacterial activity may be beneficial. In this study, lysozyme (LY) and collagen (Col) were alternately deposited on silk fibroin (SF) and nylon 6 (N6) composite nanofibrous mats using a layer-by-layer (LBL) self-assembly technique. The mechanical properties, biocompatibility, and antibacterial activity of the LBL structured mats were characterized systematically to investigate the impact of the LBL process on the biological properties of SF/N6 nanofibrous mats. Our results showed that the effective deposition of LY and Col may affect the surface topography, mechanical properties, and wetting behavior of the SF/N6 nanofibrous mats. Moreover, LBL structured mats exhibited excellent biocompatibility and antibacterial properties. Among all the tested mats, those coated with 10 bilayers of LY and Col displayed the best biocompatibility, and relatively good mechanical and antibacterial properties. Thus, LBL structured mats, especially those with a 10 bilayer coating, are potentially valuable in clinical therapy for pelvic organ prolapse in the future.

Egg source natural proteins LBL modified cellulose nanofibrous mats and their cellular compatibility

Natural-based nanocomposites are competitive and promising materials for biomedical applications due to their biocompatibility. Herein, a novel natural-based composite was fabricated by alternately depositing lysozyme (LY) and albumin egg (AE) on electrospun cellulose nanofibrous mats via layer-by-layer self-assembly (LBL) technology. To indicate the successful deposition process and investigate the variations of the mats during LBL process, the surface morphology, physical property, chemical composition, wetting behavior and thermal stability were systematically studied. The results showed that the surface morphology and composition of the mats were significantly influenced by LBL process, which further resulted in the variation of wetting behavior. Besides, the mechanical properties were enhanced after LBL modification. In addition, the LBL structured nanofibrous mats exhibited antibacterial activity and excellent biocompatibility with L929 fibroblasts. In brief, LY and AE coated LBL structured cellulose nanofibrous mats, especially the 15 bilayers coated mats, have considerably potential applications in the biomedical field.

What is new in lysozyme research and its application in food industry? A review

Lysozyme, an important bacteriostatic protein, is widely distributed in nature. It is generally believed that the high efficiency of lysozyme in inhibiting gram-positive bacteria is caused by its ability to cleave the β-(1,4)-glycosidic bond between N-acetylmuramic acid and N-acetylglucosamine. In recent years, there has been growing interest in modifying lysozyme via physical or chemical interactions in order to improve its sensitivity against gram-negative bacterial strains. This review addresses some significant techniques, including sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), infrared (IR) spectra, fluorescence spectroscopy, nuclear magnetic resonance (NMR), UV-vis spectroscopy, circular dichroism (CD) spectra and differential scanning calorimetry (DSC), which can be used to characterize lysozymes and methods that modify lysozymes with carbohydrates to enhance their various physicochemical characteristics. The applications of biomaterials based on lysozymes in different food matrices are also discussed.

A novel bioassay based on aptamer-functionalized magnetic nanoparticle for the detection of zearalenone using time resolved-fluorescence NaYF4: Ce/Tb nanoparticles as signal probe

Zearalenone (ZEN) is a non-steroidal estrogenic mycotoxin produced by fungi on stored grains. The earlier detection methods used for ZEN rely on expensive equipment, time-consuming sample preparation and temperature sensitive antibodies. The current work, proposed a novel strategy based on ZEN aptamer labeled with amine-functionalized magnetic nanoparticle (MNPs) as a capture probe and time-resolved fluorescence (TRFL) nanoparticles labeled with complementary DNA (cDNA) as a signal probe. Under the optimized conditions, TRFL intensity at 544 nm was used to measure ZEN (R² = 0.9920) in the range of 0.001-10 ng mL^-1 and limits of detection (LOD) for proposed method was 0.21 pg mL^-1. The specificity of bioassay was also determined by using other mycotoxins (OTA, AFB₂, DON and Patulin) and results showed that the aptamer are specific to recognize only ZEN. The analytical applications of the present bioassay in maize and wheat samples were also examined and results were compared with existing methods. Based on these findings, it is suggested to use current rapid and simple bioassay for the determination of ZEN in food and agricultural products.

Effect of exogenous metal ions and mechanical stress on rice processed in thermal-solid enzymatic reaction system related to further alcoholic fermentation efficiency

Metal-rich thermal-solid enzymatic processing of rice combined with yeast fermentation was investigated. 8 Metal ions were exogenously supplied at 0.05, 0.5 and 5mmol/100g (MG) rice prior to static high pressure enzymatic cooking (HPEC) and dynamic enzymatic extrusion cooking (EEC). Treated rice and its fermentation efficiency (FE) were characterized by rapid viscosity analyzer (RVA), UV-Vis, FT-IR and atomic absorption spectrophotometer (AAS). The optimum pH range of enzyme in solid system (>4.9) was broader than in a liquid system (>5.5). Cations decreased enzymatic activity in HPEC probably due to metal-induced aggregation of rice matrix with reduced reacting area as well as strengthened structure of starch/polysaccharides modified by metals. While using the EEC with mechanical mixing/shearing, relative activity was activated to 110 and 120% by Mg²⁺ (0.05-0.5MG) and Ca²⁺ (0.05-5MG), respectively. Furthermore, the effectiveness of residual ions to promote further FE was found to follow the order: Ca²⁺>K⁺>Zn²⁺>Mg²⁺>Mn²⁺>Na⁺≈Control>Fe²⁺>Cu²⁺, individually.

Bimodal counterpropagating-responsive sensing material for the detection of histamine

A dual-mode system for simultaneous fluorescence and SERS sensing of histamine.