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Block copolymers based on fish collagen and chitosan were obtained by ultrasonic irradiation of a blend of homopolymers. The molecular weight of the block copolymer was 310 kDa. The tensile strength of the block copolymer film increases by more than 200% compared to the original chitosan and by 145% compared to films based on a mechanical blend of collagen and chitosan, and amounts to 123 MPa. The growth density of hTert-BJ5ta fibroblast cells on the surface of film samples was calculated. For chitosan, the cell growth density was 97,000 cells/cm2. Films made from mechanical blend were characterized by the lowest adhesion and cell proliferation - 35,000 cells/cm2. However, the block copolymer films had a significant cell growth density - 90,000 cells/cm2, which is close to the values of the original chitosan. The totality of the results obtained shows that compositions based on block copolymers are superior to films made from homopolymers and their blends in mechanical properties, adhesion and proliferation of fibroblast cells, which is important for their use in tissue engineering. [ABSTRACT FROM AUTHOR]

The following article provides an insight into the production of chitosan aerogels as potential materials for tissue engineering. Chitosan aerogels were prepared following two different protocols: formation in ethanol and formation in sodium hydroxide in an ethanol solution. The main objective was to apply a new route to obtain chitosan aerogels with no external cross-linkers and compare the mentioned preparation approaches. Forming chitosan aerogels in ethanol implies a simple, environmentally friendly, and efficient method. The prepared materials showed specific surface areas of up to 450 m2/g, highly porous networks and great mechanical properties. In vitro degradation studies revealed high stability for up to 10 weeks. The differences between the samples were significant. While the chitosan aerogels prepared in ethanol showed superior textural, morphological and mechanical properties, the chitosan aerogels prepared in the sodium hydroxide solution proved that a considerable influence on end properties could be made simply by adjusting the ageing medium. In vitro cell analysis with primary human osteoblasts showed good biocompatibility and pointed towards the potential use of these aerogels for orthopedic applications. This testing showed further that adjustments in structural properties by sodium hydroxide also come with a cost regarding their suitability to host bone cells. • Chitosan aerogels as potential materials for tisssue engineering. • Chitosan aerogels prepared in ethanol showed superior properties. • Considerable influence on the structure can be made by simply adjusting the formation medium. • Potential use of chitosan aerogels for orthopedic applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Highly dispersible TiO 2 was successfully applied to prepare zein/CS/TiO 2 films. • The films modified by nano-TiO 2 showed better mechanical properties than control. • The films modified by nano-TiO 2 showed better thermal stability than control. • Significant antibacterial activity against gram-negative and gram-positive bacteria. Abstract Highly dispersible TiO 2 nanoparticles were prepared through the hydrolysis of titanium alcohol, and a series of TiO 2 -modified zein/chitosan (CS) films were prepared through a process involving blending, solution casting and evaporation. The mechanical properties and the antibacterial capacity of the zein/CS/TiO 2 films were characterized to explore the effects of different TiO 2 nanoparticle contents. Results showed that the addition of nanoscale TiO 2 remarkably improved the mechanical properties and thermal stability of the zein/CS/TiO 2 film. The tensile strength of the zein/CS/TiO 2 films significantly increased (p<0.05) with the increasing TiO 2 loadings in films, reaching a maximum of 28.33 ± 1.53 MPa at 0.15 wt % TiO 2 nanoparticles. The antibacterial effect of the composite films on Gram-positive bacteria (S. aureus) was more significant than that of Gram-negative bacteria (E. coli and S. enteritidis), and the antibacterial effect of UV light was better than that of dark conditions. In particular, the inhibition zones of zein/CS/TiO 2 (0.15%) film against E. coli , S. enteritidis and S. aureus under UV light condition increased by 21.78%, 21.45%, and 26.44%, respectively, compared with the control. This study suggested that adding highly dispersible TiO 2 nanoparticles is an effective method for improving the mechanical and antimicrobial properties of zein/CS films for various applications, such as medical and food packaging. [ABSTRACT FROM AUTHOR]

Microparticles (MPs) exhibit fast dissolution, characterized by a burst drug release pattern. In the present work, we prepared core-shell MPs of simvastatin (SIM) and zein with chitosan (CS) and nano-hydroxyapatite (nHA) as a drug carrier using the coaxial electrospray deposition method. The morphology, formation and in vitro osteogenic differentiation of these MPs were studied. The synthetic MPs have a diameter of about 1 μm and they are composed of non-toxic natural materials. They provide an effective way to enable long-term sustained-release activity, which is controlled by their double layer structures. The CS-nHA/zein-SIM MPs presented a low initial burst release (approximately 35-47%) within the first 24 h of application followed by the sustained release for at least 4 weeks. In vitro cell culture experiments were performed and the results revealed that the CS-nHA/zein-SIM core-shell MPs were beneficial to the adhesion, proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). The CS-nHA/zein-SIM MPs with a low SIM concentration were beneficial to cell proliferation and promotion of osteogenic differentiation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel two-step modification was applied for enhancing functional properties of zein films. • Cold plasma gave zein-based films a rougher and more hydrophilic surface. • Flexibility and barrier properties were significantly increased after modification. • Cold plasma enhanced the compatibility between zein and chitosan molecules. Abstract In order to improve their functional properties, zein films were modified by a two-step method consisting of compositing with chitosan, followed by exposure to cold plasma. Various aspects were assessed to evaluate the influence of modification on the properties of the films. After the two-step modification, the water contact angle of the zein films significantly dropped from 75.18° to 29.19°. Moreover, the films showed a notable increase in their elongation at break, from 1.13% to 4.13%, mainly attributed to the presence of chitosan. Additionally, upon a 60 s plasma treatment, the composite film exhibited an optimum tensile strength, an enhanced water vapor barrier as well as improved thermal stability. Evaluation with ATR-FTIR revealed the secondary structure of zein molecules became ordered and found the more hydrogen bonds formed between zein and chitosan with plasma treatment. This study showed the benefits of our two-step modification to potentially improve zein-based film performance in packaging industries. [ABSTRACT FROM AUTHOR]

Highlights • A plasma method to produce zein-coated chitosan films as a promising delivery system. • The plasma treatment provided zein-coated films a more compact interface structure. • Chitosan/drug films coated with zein showed sustained release of water-soluble drug. • Zein-coated films with cold plasma treatment exhibited a slower release property. Abstract Chitosan-based films with zein coatings were prepared in order to modify the drug release properties. The adhesion of zein layers to the films was ensured via a cold plasma treatment. Using ciprofloxacin hydrochloride as model, the effect of cold plasma on the functional properties and structures was evaluated. The results suggest that the encapsulation efficiency, chemical composition and crystal type of ciprofloxacin hydrochloride in chitosan/drug films were not altered by cold plasma treatment, while the wettability and surface free energy displayed a notable increase. After being coated with zein, the chitosan interacted with the zein through hydrogen bonding and electrostatic interactions. The burst release phenomenon of the chitosan/drug films was prevented by the zein coating. Furthermore, the plasma treatment provided the coated film with a slower release rate within 24 h, from 72.8% to 49.3%. The enhanced coating thickness and the more compact interface structure were responsible for this improvement. [ABSTRACT FROM AUTHOR]

Ellagic acid (EA) has demonstrated several biological properties, such as antioxidant, antimicrobial, and enzymatic inhibition. Zein and chitosan (CHI) are natural polymers whose biological potential has also gained attention. Therefore, this paper aimed to evaluate the antimicrobial, antioxidant, anticollagenase, and antielastase properties of EA, zein, and chitosan isolated or in combination. The microdilution method was used to assess the minimum inhibitory and bactericide concentrations. The antioxidant activity was determined using the 2,2‐diphenyl‐1‐picryl‐hydrazila free radical scavenging method. The anticollagenase and antielastase activities were evaluated by specific colorimetric tests. EA has shown inhibitory activity against Staphylococcus aureus and Pseudomonas aeruginosa together with an antioxidant IC50 of 0.079 mg/mL. EA also showed significant collagenase and elastase inhibition. Zein has shown antimicrobial and antioxidant activities itself and enhanced sinergically the antioxidant activity and the antimicrobial activity against P. aeruginosa when combined with EA. CHI increased sinergically the inhibitory activity of EA against both bacterial strains, while showed itself an acceptable antimicrobial activity. 1H saturation transfer‐difference nuclear magnetic resonance experiment confirmed the formation of a complex between EA and zein that could be related with the improvement on its biological performance over the individual compounds, while no chemical interaction was detected between CHI and EA. Practical Application: The results reinforce the potential of ellagic acid in combination with zein and/or chitosan as an antimicrobial, antienzimatic, and antioxidant agent. Those findings reinforce the use of these substances, protecting this bioactive from degradation and/or improving the functional characteristics and biopharmaceutical properties. [ABSTRACT FROM AUTHOR]

Graphical abstract The above graphic depicts the formulation methodology used to produce selenomethionine loaded chitosan nanoparticles, coated with zein, for in vitro assessment. Briefly, to produce the nanoparticles, chitosan was protonated by dissolving in acidic buffer (pH 3), then crosslinked with ionised tripolyphosphate and selenomethionine in NaOH (0.1 M). Zein coating was then employed to coat the nanoparticles and purification was achieved by removing unencapsulated formulation components through ultracentrifugation. Abstract Selenomethionine is an essential amino acid with a narrow therapeutic index and susceptibility to oxidation. Here it was encapsulated into a nanoparticle composed of chitosan cross-linked with tripolyphosphate for oral delivery. The formulation was optimised using a three-factor Box-Behnken experimental design. The chitosan:tripolyphosphate ratio, chitosan solvent pH, and drug load concentration were independently varied. The dependent variables studied were encapsulation efficiency, particle size, polydispersity index and zeta potential. For optimisation, encapsulation efficiency and zeta potential were maximised, particle diameter was set to 300 nm and polydispersity index was minimised. A 0.15 mg/mL concentration of selenomethionine, chitosan solvent pH of 3, and chitosan:tripolyphosphate ratio of 6:1 yielded optimum nanoparticles of size 187 ± 58 nm, polydispersity index 0.24 ± 0.01, zeta potential 36 ± 6 mV, and encapsulation efficiency of 39 ± 3%. Encapsulation efficiency was doubled to 80 ± 1.5% by varying pH of the ionotropic solution components and by subsequent coating of the NPs with zein, increasing NP diameter to 377 ± 47 nm, whilst retaining polydispersity index and zeta potential values. Selenomethionine-entrapped nanoparticles were not cytotoxic to intestinal and liver cell lines. Accelerated thermal stability studies indicated good stability of the nanoparticles under normal storage conditions (23 °C). In simulated gastrointestinal and intestinal fluid conditions, 60% cumulative release was obtained over 6 h. [ABSTRACT FROM AUTHOR]

The complex coacervation between zein and chitosan (CS) as well as the relationship with the controlled release properties of their complex nanoparticles were studied. The factors influencing the nanoparticle formation between zein and CS, including solid to liquid ratio, zein to CS ratio and pH, were systematically investigated. The isothermal titration calorimetry (ITC) showed that zein-CS interaction was spontaneous exothermic process. The pH the higher was, the stronger the interaction between zein and CS. The mean particle sizes of ZCNPs were increased by enhanced turbidity between zein and CS (from 90.89 nm to 1368.77 nm). The morphology study showed that spherical particles and coacervate were obtained with the increased interaction between zein and CS. The release profiles of curcumin in vitro indicated that slight burst effect followed by slow release was observed after interacting CS. The ZCNPs at pH 4.0 exhibited smaller particle size (162.07 nm), more stable ζ-potential (49.7 mV), higher encapsulation efficiency (94.67%) and slower release rate. In conclusion, the stronger the interaction was, the lower the curcumin released from the nanoparticles in vitro , and the ZCNPs at pH 4.0 had better potential in oral delivery application. [ABSTRACT FROM AUTHOR]

Propolis is a natural resinous mixture from many plant materials, buds, and exudates and is rich in polyphenols with several health beneficial properties. However, its application in food products and pharmaceuticals is hindered because of its low water solubility, undesirable sensorial characteristics and limited bio-accessibility. Here, we originally report the design and synthesis of food-grade colloidal nanoparticles as propolis carriers to enhance its oral bioavailability. Propolis was encapsulated into heat-denatured zein with carboxymethyl chitosan (CMCS) coating by acid-induced aggregation. Calcium cross-linking provided the best controlled release of propolis and improved encapsulation efficiency. The complex nanoparticles prepared under optimized conditions were spherical in shape with a Z-average diameter of ∼156 nm and zeta potential of ∼ -30 mV. Encapsulation efficiency (EE) and loading content (LC) of propolis in heat-denatured zein/CMCS nanoparticles reached∼83% and∼13.83%, respectively. Fourier transform infrared (FTIR) indicated that hydrogen bonds, electrostatic and hydrophobic interactions were the major forces responsible for nanoparticle formation. The in vitro antioxidant activity of propolis encapsulated in nanoparticles was considerably stronger than that of propolis dispersed in water. This new approach of fabricating propolis-loaded heat-denatured zein/CMCS nanoparticle provides a promising strategy with high yield and is non-toxic with improved water solubility, antioxidant activity and sustained release of propolis. [ABSTRACT FROM AUTHOR]

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In this investigation, porous composite scaffolds were prepared using a freeze-drying procedure by mixing zein (ZN), chitosan (CS) and nanohydroxyapatite (nHAp) in different inorganic/organic weight ratios. The gained nanocomposite scaffolds were studied using X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and N 2 -adsorption-desorption technique. Also, swelling, porosity, mechanical properties, biomineralization capability, degradation, cell attachment, and cell viability of the composite scaffolds were studied. The results showed a porous nature with acceptable pore dimensions and interconnections for cell penetration and colonization. In addition, the cytocompatibility of the ZN/CS/nHAp scaffolds was surveyed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) evaluation and cell attachment studies using human bone cancer cells. Studies indicated non- toxicity to the cells, and the cells were found to be attached to the pore walls within the scaffolds. The results related to physicochemical properties and superior cytocompatibility suggested that ZN/CS/nHAp scaffold could be potential candidate materials for the tissue engineering. [ABSTRACT FROM AUTHOR]

Edible films (EFs) have gained great interest due to their ability to keep foods safe, maintaining their physical and organoleptic properties for a longer time. The aim of this work was to develop EFs based on a chitosan-zein mixture with three different essential oils (EOs) added: anise, orange, and cinnamon, and to characterize them to establish the relationship between their structural and physical properties. The addition of an EO into an EF significantly affected (p < 0.05) the a* (redness/greenness) and b* (yellowness/blueness) values of the film surface. The EFs presented a refractive index between 1.35 and 1.55, and thus are classified as transparent. The physical properties of EFs with an added EO were improved, and films that incorporated the anise EO showed significantly lower water vapor permeability (1.2 ± 0.1 g mm h-1 m-2 kPa-1) and high hardness (104.3 ± 3.22 MPa). EFs with an added EO were able to inhibit the growth of Penicillium sp. and Rhizopus sp. to a larger extent than without an EO. Films' structural changes were the result of chemical interactions among amino acid side chains from zein, glucosamine from chitosan, and cinnamaldehyde, anethole, or limonene from the EOs as detected by a Raman analysis. The incorporation of an EO in the EFs' formulation could represent an alternative use as coatings to enhance the shelf life of food products. [ABSTRACT FROM AUTHOR]

The oral route is an attractive delivery route for the administration of DNA-based therapeutics, specifically for applications in gene therapy and DNA vaccination. However, oral DNA delivery is complicated by the harsh and variable conditions encountered throughout gastrointestinal (GI) transit, leading to degradation of the delivery vector and DNA cargo, and subsequent inefficient delivery to target cells. In this work, we demonstrate the development and optimization of a hybrid-dual particulate delivery system consisting of two natural biomaterials, zein (ZN) and chitosan (CS), to mediate oral DNA delivery. Chitosan-Zein Nano-in-Microparticles (CS-ZN-NIMs), consisting of core Chitosan/DNA nanoparticles (CS/DNA NPs) prepared by ionic gelation with sodium tripolyphosphate (TPP), further encapsulated in ZN microparticles, were formulated using a water-in-oil emulsion (W/O). The resulting particles exhibited high CS/DNA NP loading and encapsulation within ZN microparticles. DNA release profiles in simulated gastric fluid (SGF) were improved compared to un-encapsulated CS/DNA NPs. Further, site-specific degradation of the outer ZN matrix and release of transfection competent CS/DNA NPs occurred in simulated intestinal conditions with CS/DNA NP cores successfully mediating transfection in vitro. Finally, CS-ZN-NIMs encoding GFP delivered by oral gavage in vivo induced the production of anti-GFP IgA antibodies, demonstrating in vivo transfection and expression. Together, these results demonstrate the successful formulation of CS-ZN-NIMs and their potential to improve oral gene delivery through improved protection and controlled release of DNA cargo. [ABSTRACT FROM AUTHOR]

This research aimed to evaluate the physicochemical and biocidal properties of chitosan films obtained through the solvent casting method using two different molecular weights, and thermally treated for an extended time (3 weeks) at 70 °C under vacuum condition (RH 0 %). The effect of storage time (for 30 and 180 days) under ambient conditions (23 °C and RH 40 %) on the properties of heat-treated cast films and their biocidal effectiveness was also assessed. FTIR-ATR, TGA and XRD of resulting films were analyzed to explore the dependency of antibacterial performance on the alteration in molecular and chemical structure. The results demonstrated that the solubility of treated films at 70 °C was proportionally reduced, resulting from the reduction of protonated amines and an increase in crystallinity. Likewise, increasing storage time led to a significant lowering in the solubilization of cast films. It was found that the solubilized fraction of chitosan cast films is the active fraction with the biocide behavior that can act against bacteria. In addition, the effectiveness of migrated chitosan was examined against the natural flora of pasteurized milk, such as Paenibacillus and Pseudomonas fluorescens. The results showed that cast films obtained from chitosan with lower molecular weight caused a reduction in the total count of viable cells without a significant effect on the properties of milk. [ABSTRACT FROM AUTHOR]

Traditional emulsion adjuvants are stabilized by non-ionic surfactants and promote high humoral immunity. However, because of their electroneutrality, they cannot effectively carry negatively charged antigens and enter the cell to elicit cellular immunity. To overcome this problem, we developed an emulsion using chitosan hydrochloride salt (CSCL) as stabilizer. After optimization, CSCL was successfully adsorbed on the surface of the emulsion (CPSE), and stabilized for two months. CPSE could effectively loading the antigen and slow down the rate of the antigen release. We evaluated the effectiveness of CPSE through intramuscular immunization in mice after cytotoxicity assay proved its safety. CPSE not only induced strong antibody-mediated immune responses, but also generated memory T cells in the spleen as a marker of adaptive immunity. Importantly, CPSE showed advantages over the conventional vaccine formulations in promoting IFN-γ secretion. CPSE may act as a promising candidate to enhance the efficacy of vaccines with acceptable biocompatibility and safety. [Display omitted] [ABSTRACT FROM AUTHOR]

Double enzymes (alcalase and trypsin) were effectively immobilized in a composite carrier (calcium alginate–chitosan) to produce immobilized enzyme beads referred to as ATCC. The immobilization conditions for ATCC were optimized, and the immobilized enzyme beads were characterized. The optimal immobilization conditions were 2.5% of sodium alginate, 10:4 sodium alginate to the double enzymes, 3:7 chitosan solution to CaCl2 and 2.5 h immobilization time. The ATCC beads had greatly enhanced stability and good usability compared with the free form. The ATCC residual activity was retained at 88.9% of DH (degree of hydrolysis) after 35 days of storage, and 36.0% of residual activity was retained after three cycles of use. The beads showed a higher zein DH (65.8%) compared with a single enzyme immobilized in the calcium alginate beads (45.5%) or free enzyme (49.3%). The ATCC kinetic parameters Vmax and apparent Km were 32.3 mL/min and 456.62 g−1, respectively. Active corn peptides (CPs) with good antioxidant activity were obtained from zein in the ethanol phase. The ATCC might be valuable for preparing CPs and industrial applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] Thymol was successfully loaded into zein nanoparticles using a low energy method. [•] Sodium caseinate and chitosan hydrochloride were used as the stabilizer layers. [•] Stabilized zein nanoparticles had a desirable redispersibility in water. [•] Improved encapsulation efficiency was achieved with double stabilizer layers. [•] Encapsulated thymol showed stronger antimicrobial activity for a longer time period. [ABSTRACT FROM AUTHOR]

Abstract: Different methods of polymer grafting using gamma irradiation are reported in the present study for the preparation of newly functionalized biodegradable films, and some important properties related to their mechanical and barrier properties are described. Biodegradable films composed of zein and poly(vinyl alcohol) (PVA) were gamma-irradiated in presence of different ratios of acrylic acid (AAc) monomer for compatibilization purpose. Resulting grafted films (zein/PVA-g-AAc) had their puncture strength (PS=37–40Nmm−1) and puncture deformation (PD=6.5–9.8mm) improved for 30% and 50% PVA in blend, with 5% AAc under 20kGy. Methylcellulose (MC)-based films were irradiated in the presence of 2-hydroxyethyl methacrylate (HEMA) or silane, in order to determine the effect of monomer grafting on the mechanical properties of films. It was found that grafted films (MC-g-HEMA and MC-g-silane) using 35% monomer performed higher mechanical properties with PS values of 282–296Nmm−1 and PD of 5.0–5.5mm under 10kGy. Compatibilized polycaprolactone (PCL)/chitosan composites were developed via grafting silane in chitosan films. Resulting trilayer grafted composite film (PCL/chitosan-g-silane/PCL) presented superior tensile strength (TS=22MPa) via possible improvement of interfacial adhesion (PCL/chitosan) when using 25% silane under 10kGy. Finally, MC-based films containing crystalline nanocellulose (CNC) as a filling agent were prepared and irradiated in presence of trimethylolpropane trimethacrylate (TMPTMA) as a grafted plasticizer. Grafted films (MC-g-TMPTMA) presented superior mechanical properties with a TS of 47.9MPa and a tensile modulus (TM) of 1792MPa, possibly due to high yield formation of radicals to promote TMPTMA grafting during irradiation. The addition of CNC led to an additional improvement of the barrier properties, with a significant 25% reduction of water vapor permeability (WVP) of grafted films. [Copyright &y& Elsevier]

Abstract: The use of composite edible films made from biopolymers has attracted interest as a way to reduce pollution and recycling problems; however, the relation between barrier, mechanical and structural properties of the films have been scarcely studied. The aim of this work was to evaluate composite zein–chitosan edible films by applying common nanotechnology tools and to relate the results to zein concentration and film structural changes. Rougher, more elastic, and less hard film structures with better water vapour barrier properties were obtained using larger zein concentrations. Raman spectroscopy exhibited unexpected interactions, as indicated by the disappearance of the thiol groups of cysteine in the zein films and the appearance of O S O and C O S groups in the blended materials in conjunction with the disappearance of zein ɛ-amino and NH2 functional groups in the zein film samples, thereby confirming changes in the blended film structure. Zein concentration presented linear correlations with water vapour permeability (R =−0.978) and film roughness (R =0.929). The composite films presented better barrier and mechanical properties than single ingredient films. This information shows the benefit of using protein–polysaccharide blends to prepare edible films. [Copyright &y& Elsevier]

Fabrication, via electrospinning, and characterization of an ultrafine structure architected from a blend of hydrophobic zein and hydrophilic chitosan (CS) were conducted. Poly(ethylene oxide) (PEO) and nonionic surfactant, namely, Tween® 40, were employed to improve the electrospinnability of the blend, while ethanol was used as a solvent for zein. The effects of ethanol (EtOH) concentration (85% and 90%) and ratio of zein/PEO/CS (95/2.5/2.5 and 87.5/10/2.5) on the fiber morphology as well as gastromucoadhesivity against porcine stomach mucosa were then investigated; polymer-mucosa adhesion was also investigated via Fourier-transform infrared spectroscopy. Swelling and degradation of the composite ultrafine fibers were investigated under 2 simulated gastric conditions, namely, at pH 2 without pepsin and at pH 1.2 with pepsin. Using 85% EtOH as a solvent for zein resulted in a spider-web-like morphology; the maximum detachment force (MDF), which is an indirect indicator of the gastromucoadhesivity was nevertheless higher. Zein-based ultrafine fibers exhibited higher MDF than the zein-PEO-CS composite; however, the cohesiveness of the composite fibers was higher. FTIR spectroscopic results indicated molecular interactions between the composite fibers and mucin functional groups. Swelling of the composite ultrafine fibers in simulated gastric fluid (SGF) at pH 2 without pepsin was not different from that in SGF at pH 1.2 with pepsin. Nevertheless, degradation of the composite fibers in SGF at pH 2 without pepsin was much less than that in SGF at pH 1.2 with pepsin; only 20% degradation was noted in the former case. [ABSTRACT FROM AUTHOR]