Isobornyl and Isocamphyl Photostabilizers in Poly(lactic acid)-Based Electrospun Fibers.

In this work, electrospun polylactide fibers with new photostabilizing additives, 4-methyl-2,6-diisobornylphenol (DIBP) and N-isocamphylaniline (NICA), have been tested under the influence of UV-C radiation (254 nm). The changes in the polymers' chemical structure under UV-C radiation were revealed through the increase in absorption in the 3600-3100 cm-1 region in regard to the FTIR spectra. In the samples that were irradiated for 1 h, the stabilizing effect of the photoprotectors became most noticeable as the difference in the content of the hydroxyl groups in stabilized and the pure PLA reached a maximum. The TG-DSC method revealed that the most sensitive indicator of the irradiation effect was the glass transition temperature (Tg), which persisted after 2 h of irradiation when using photostabilizers and their combinations. The PLA/DIBP(1) and PLA/NICA(1) samples showed the best results in protecting PLA from UV-C radiation based on the Tg values; although, the mixture of DIBP and NICA was not as effective. The chemical structure of the photostabilized PLA samples was studied using NMR, GPC, and Py-GC/MS analysis. The electrospun polylactide fibers were mechanically tested and the effects of the electrospun samples on cell viability were studied.

Effect of Homogenized Callus Tissue on the Rheological and Mechanical Properties of 3D-Printed Food.

The aim of the study was to develop ink enriched with a high content of lupine callus tissue (CT) suitable for 3D printing. Printable ink obtained using mashed potatoes (20 g/100 mL) and a 3% agar solution was used as the parent CT-free ink (CT0). Viscosity increased from 9.6 to 75.4 kPa·s during the cooling of the CT0 ink from 50 to 20 °C, while the viscosity of the ink with 80 g/100 mL of CT (CT80) increased from 0.9 to 5.6 kPa·s under the same conditions. The inclusion of CT was shown to decrease the hardness of 3D-printed food gel from 0.32 ± 0.03 to 0.21 ± 0.03 N. The storage modulus G' value was 7.9 times lower in CT80 samples than in CT0 samples. The values of fracture stress for CT80 and CT0 inks were 1621 ± 711 and 13,241 ± 2329 Pa, respectively. The loss tangent and the limiting strain did not differ in CT0 and CT80, although the value of the fracture strain was 1.6 times higher in the latter. Thus, the present study demonstrates that CT may be added to printing ink in order to enhance food with plant cell material and enable the 3D printing of specially shaped foods.

Anti-Alzheimer Drug Delivery via Pickering Emulsions Stabilized by Plate-like Cellulose Nanocrystals.

In this work, we studied for the first time the formation of olive oil emulsions in water stabilized by plate-like nanocrystals with the supramolecular structure of cellulose II (pCNC). Effects of storage, pCNC concentration, and NaCl on the stability and properties of Pickering emulsions, including the creaming index, droplet size, zeta potential, acid-base surface properties, and rheology, were studied. A significant influence of the shape of nanoparticles (compared to the classical rod-like shape) on the stability parameters and rheological characteristics of emulsions is shown. Plate-like cellulose nanocrystals at a concentration of 16 g/L are able to form delamination-resistant emulsions without added electrolytes. The viscosity of pCNC-stabilized emulsions tends to decrease with increasing electrolyte concentration in the system, which is not characteristic of rod-like CNC-stabilized emulsions. This effect in pCNC-stabilized emulsions assumedly can be associated both with weak mechanical engagement between drops due to the shape of stabilizer particles and with an insignificant participation of background electrolyte cations in the formation of interdroplet interactions. Therefore, the resulting aggregates are unstable and easily destroyed, even under weak mechanical stress. As a consequence, the acid-base properties of the pCNC surface are practically independent of the emulsion preparation method (with or without electrolyte) as well as the concentration of the background electrolyte. The reduced viscosity of pCNC-stabilized emulsions in the presence of an electrolyte, coupled with the absence of acute toxicity, allows us to recommend them as a convenient oral delivery system for fat-soluble, biologically active substances. Our emulsions carrying donepezil (an anti-Alzheimer drug) showed better performance than a solution of donepezil hydrochloride in preventing memory impairment tested on laboratory mice.

Effect of Chitosan on Rheological, Mechanical, and Adhesive Properties of Pectin-Calcium Gel.

In the present study, chitosan was included in the pectin ionotropic gel to improve its mechanical and bioadhesive properties. Pectin-chitosan gels P-Ch0, P-Ch1, P-Ch2, and P-Ch3 of chitosan weight fractions of 0.00, 0.25, 0.50, and 0.75 were prepared and characterized by dynamic rheological tests, penetration tests, and serosal adhesion ex vivo assays. The storage modulus (G') and loss modulus (G″) values, gel hardness, and elasticity of P-Ch1 were significantly higher than those of P-Ch0 gel. However, a further increase in the content of chitosan in the gel significantly reduced these parameters. The inclusion of chitosan into the pectin gel led to a decrease in weight and an increase in hardness during incubation in Hanks' solution at pH 5.0, 7.4, and 8.0. The adhesion of P-Ch1 and P-Ch2 to rat intestinal serosa ex vivo was 1.3 and 1.7 times stronger, whereas that of P-Ch3 was similar to that of a P-Ch0 gel. Pre-incubation in Hanks' solution at pH 5.0 and 7.4 reduced the adhesivity of gels; however, the adhesivity of P-Ch1 and P-Ch2 exceeded that of P-Ch0 and P-Ch3. Thus, serosal adhesion combined with higher mechanical stability in a wide pH range appeared to be advantages of the inclusion of chitosan into pectin gel.

Effect of Hogweed Pectin on Rheological, Mechanical, and Sensory Properties of Apple Pectin Hydrogel.

This study aims to develop hydrogels from apple pectin (AP) and hogweed pectin (HP) in multiple ratios (4:0; 3:1; 2:2; 1:3; and 0:4) using ionotropic gelling with calcium gluconate. Rheological and textural analyses, electromyography, a sensory analysis, and the digestibility of the hydrogels were determined. Increasing the HP content in the mixed hydrogel increased its strength. The Young's modulus and tangent after flow point values were higher for mixed hydrogels than for pure AP and HP hydrogels, suggesting a synergistic effect. The HP hydrogel increased the chewing duration, number of chews, and masticatory muscle activity. Pectin hydrogels received the same likeness scores and differed only in regard to perceived hardness and brittleness. The galacturonic acid was found predominantly in the incubation medium after the digestion of the pure AP hydrogel in simulated intestinal (SIF) and colonic (SCF) fluids. Galacturonic acid was slightly released from HP-containing hydrogels during chewing and treatment with simulated gastric fluid (SGF) and SIF, as well as in significant amounts during SCF treatment. Thus, new food hydrogels with new rheological, textural, and sensory properties can be obtained from a mixture of two low-methyl-esterified pectins (LMPs) with different structures.

Serosal Adhesion Ex Vivo of Hydrogels Prepared from Apple Pectin Cross-Linked with Fe3+ Ions.

The study aims to investigate the adhesion of a hydrogel made of cross-linked low-methyl esterified pectin to rat intestinal serosa ex vivo. The adhesivity of the FeP hydrogel, which was cross-linked by Fe3+ cations, exceeded that of hydrogels cross-linked by Ca2+, Zn2+, and Al3+ cations. The concentration of the cross-linking cation failed to influence the adhesion of the pectin hydrogel to the serosa. The mechanical properties and surface microrelief of the pectin hydrogel were influenced by the type and concentration of the cross-linking cations. Fe3+ cations form a harder and more elastic gel than Ca2+ cations. Scanning electron microscopy analysis revealed the characteristic surface pattern of FeP hydrogel and its denser internal structure compared to Ca2+ cross-linked hydrogel. The effect of the salt composition of the adhesion medium was shown since the FeP hydrogel's adhesion to the serosa was lower in physiological solutions than in water, and adhesion in Hanks' solution was higher than in phosphate buffered saline. Serum proteins and peritoneal leukocytes did not interfere with the serosal adhesion of the FeP hydrogel. Pre-incubation in Hanks' solution for 24 h significantly reduced the adhesion of the FeP hydrogel to the serosa, regardless of the pH of the incubation. Thus, serosal adhesion combined with excellent stability and mechanical properties in physiological environments appeared to be advantages of the FeP hydrogel, demonstrating it to be a promising bioadhesive for tissue engineering.

Effect of Cross-Linking Cations on In Vitro Biocompatibility of Apple Pectin Gel Beads.

The study aimed to compare the in vitro biocompatibility of pectin gels formed by different cross-linking cations. Hydrogel beads named CaPG, ZnPG, FePG, and AlPG were prepared from 4% solutions of apple pectin using ionotropic gelling with CaCl2, ZnCl2, FeCl3, and AlCl3, respectively. Cations influenced the gel strength of the wet gel beads in the following order (least strong) Ca2+ < Zn2+ < Fe3+~Al3+ (most strong). The swelling degree of the CaPG beads after 24 h of incubation in the RPMI-1640 medium was 104%, whereas the ZnPG, FePG, and AlPG beads swelled by 76, 108, and 134%, respectively. The strength of the pectin gel decreased significantly after incubation in the RPMI-1640 medium for 24 h, regardless of the cross-linking cation, although the FePG beads remained the strongest. All the pectin beads adsorbed serum proteins to a low degree, however the serum protein adsorption by the ZnPG and FePG beads (1.46 ± 0.87 and 1.35 ± 0.19 µg/mm2) was more than the CaPG and AlPG beads (0.31 ± 0.36 and 0.44 ± 0.25 µg/mm2). All the pectin beads reduced the production of TNF-α and IL-10 by hPBMCs in response to LPS stimulation. The IL-1ß response of cells to LPS was significantly reduced by the CaPG, ZnPG, and FePG beads, whereas the AlPG beads enhanced it twofold. The CaPG, FePG, and AlPG beads had no cytotoxicity. The viability of hPBMCs and human fibroblasts incubated with ZnPG beads was 5.3 and 7.2%, respectively. Thus, the use of different cross-linking cations changed the properties of the pectin gel, which is important for biocompatibility.

Enrichment of Agar Gel with Antioxidant Pectin from Fireweed: Mechanical and Rheological Properties, Simulated Digestibility, and Oral Processing.

The aims of the study were to evaluate the influence of pectin isolated from fireweed (FP) on the mechanical and rheological properties of agar (A) gel, to investigate the release of phenolic compounds (PCs) and pectin from A-FP gels at simulated digestion in vitro, and to evaluate the oral processing and sensory properties of A-FP gels. The hardness of A-FP gels decreased gradually with the increase in the concentration of FP added (0.1, 0.4, and 1.6%). The hardness of A-FP1.6 gel was 41% lower than A gel. Rheological tests found A gel was a strong physical gel (storage modulus (G') >>loss modulus (G″)), and the addition of FP up to 1.6% did not significantly change its G'. The G″ value decreased in A-FP gels compared to A gel. The release of galacturonic acid (GalA) was 3.4 ± 0.5, 0.5 ± 0.2, 2.4 ± 1.0, and 2.2 ± 0.7 mg/mL after digestion of A-FP1.6 gel in the oral in vivo phase (OP) and subsequent incubation in simulated gastric (SGF), intestinal (SIF), and colonic (SCF) fluids in vitro. The incubation medium after OP, SGF, and SIF digestion of A-FP1.6 contained 24−64 µg GAE/mL of PCs, while SCF contained 144 µg GAE/mL, supposing a predominant release of antioxidant activity from the gel in the colon. Chewing to readiness for swallowing A-FP gel required less time and fewer chews with less activity of the masseter and temporalis muscles. A-FP1.6 gel had a lower likeness score for taste and consistency and a similar score for appearance and aroma when compared with A gel. Thus, A-FP gels were weakened compared to A gel and required less time and muscle activity for oral processing. A-FP gel had antioxidant activity due to the PCs associated with pectin, while A gel had no antioxidant activity.

Biocompatible Nanoparticle Heteroaggregates as Stabilizers of Pickering Emulsions for Vitamin D3 Efficient Delivery.

Vitamin D3 deficiency is a major public health problem worldwide, and standard cholecalciferol formulations provide poor absorbability of the vitamin. Several biphasic formulas have been proposed to overcome the disadvantages in which Pickering emulsions stand out in particular. This paper describes olive oil-in-water Pickering emulsions stabilized by pseudoboehmite (AlOOH), cellulose nanocrystals (CNC), and their heterocoagulates. Colloidal properties were assessed by laser Doppler microelectrophoresis, potentiometric titration, and rheology. It was shown that the heterocoagulation of CNC and AlOOH led to a drastic change in surface properties (ζ-potential, pKa, and number of active centers), which promoted the formation of more stable emulsions with the smallest size of droplets and the highest viscosity among the studied samples. Simulated digestion studies showed the targeted release in the small intestine medium where cholecalciferol should be delivered. High-performance liquid chromatography showed the efficient encapsulation of cholecalciferol in emulsions (86% of initial concentration). Oral administration to laboratory mice of initial nanoparticles and emulsions stabilized by them showed nontoxicity for all of the components, and they were estimated to be class V materials. The proposed emulsions have great potential as targeted delivery systems of lipophilic drugs.

Surface, rheopexy, digestive stability and toxicity of olive oil emulsions stabilized by chitin nanocrystals for vitamin D3 delivery.

Pickering emulsions are of interest in medicament transport systems. The properties of emulsions are influenced by the type of oil and the surface structure of nanoparticles-stabilizers. The process of formation of o/w emulsions of olive oil stabilized by chitin nanocrystals was investigated, their stability under the influence of physical factors, rheological characteristics, acute toxicity after oral administration, stability under the conditions of a model of the gastrointestinal tract, and their potential for oral transport of vitamin D3 were analyzed. Physically stable emulsions were obtained at a stabilizer concentration of 3.6 g/l. The addition of electrolyte leads to a substantial reduction in the average size of microdroplets. The resulting emulsions have rheopexy properties and the rheopexy index increases at 37 °C. Emulsions are classified as non-toxic when taken orally, physically stable in the upper digestive system, and capable of efficiently transporting vitamin D3 with a full release in the small intestine.

Swelling, Protein Adsorption, and Biocompatibility In Vitro of Gel Beads Prepared from Pectin of Hogweed Heracleum sosnówskyi Manden in Comparison with Gel Beads from Apple Pectin.

The study aims to develop gel beads with improved functional properties and biocompatibility from hogweed (HS) pectin. HS4 and AP4 gel beads were prepared from the HS pectin and apple pectin (AP) using gelling with calcium ions. HS4 and AP4 gel beads swelled in PBS in dependence on pH. The swelling degree of HS4 and AP4 gel beads was 191 and 136%, respectively, in PBS at pH 7.4. The hardness of HS4 and AP4 gel beads reduced 8.2 and 60 times, respectively, compared with the initial value after 24 h incubation. Both pectin gel beads swelled less in Hanks' solution than in PBS and swelled less in Hanks' solution containing peritoneal macrophages than in cell-free Hanks' solution. Serum protein adsorption by HS4 and AP4 gel beads was 118 ± 44 and 196 ± 68 µg/cm2 after 24 h of incubation. Both pectin gel beads demonstrated low rates of hemolysis and complement activation. However, HS4 gel beads inhibited the LPS-stimulated secretion of TNF-α and the expression of TLR4 and NF-κB by macrophages, whereas AP4 gel beads stimulated the inflammatory response of macrophages. HS4 gel beads adsorbed 1.3 times more LPS and adhered to 1.6 times more macrophages than AP4 gel beads. Thus, HS pectin gel has advantages over AP gel concerning swelling behavior, protein adsorption, and biocompatibility.

Characterization and Biocompatibility Properties In Vitro of Gel Beads Based on the Pectin and κ-Carrageenan.

This study aimed to investigate the influence of kappa (κ)-carrageenan on the initial stages of the foreign body response against pectin gel. Pectin-carrageenan (P-Car) gel beads were prepared from the apple pectin and κ-carrageenan using gelling with calcium ions. The inclusion of 0.5% κ-carrageenan (Car0.5) in the 1.5 (P1.5) and 2% pectin (P2) gel formulations decreased the gel strength by 2.5 times. Car0.5 was found to increase the swelling of P2 gel beads in the cell culture medium. P2 gel beads adsorbed 30-42 mg/g of bovine serum albumin (BSA) depending on pH. P2-Car0.2, P2-Car0.5, and P1.5-Car0.5 beads reduced BSA adsorption by 3.1, 5.2, and 4.0 times compared to P2 beads, respectively, at pH 7. The P1.5-Car0.5 beads activated complement and induced the haemolysis less than gel beads of pure pectin. Moreover, P1.5-Car0.5 gel beads allowed less adhesion of mouse peritoneal macrophages, TNF-α production, and NF-κB activation than the pure pectin gel beads. There were no differences in TLR4 and ICAM-1 levels in macrophages treated with P and P-Car gel beads. P2-Car0.5 hydrogel demonstrated lower adhesion to serous membrane than P2 hydrogel. Thus, the data obtained indicate that the inclusion of κ-carrageenan in the apple pectin gel improves its biocompatibility.

Hemocompatibility, biodegradability and acute toxicity of acetylated cellulose nanocrystals of different types in comparison.

Promotion of promising cellulose nanocrystals (CNC) is largely dependent on the relationship between their morphology, surface chemical composition, and supramolecular structure with toxicity, hemocompatibility, and biodegradability. This paper outlines comparative and integrated analysis of the mentioned biocompatibility aspects of partially acetylated rod-, and disc-lake morphology of CNC with crystalline cellulose allomorphs I and II. These data have also included the study of CNC obtained from the sulfuric acid solutions. The aqueous solution of all types of tested CNC has not been toxic to mice after oral administration. Morphology of internal organs has not changed. However, in case of disc-like particles, the kidney mass coefficient noticeably changed. CNC have neither triggered platelet aggregation nor destroyed the red cell membrane. Intravenous administration to rabbits has not affected the plasma clotting time. Rod-like CNC are more resistant, and the disc-like particles are more susceptible to degradation under the influence of cellulases.

Wrist temperature and cortisol awakening response in humans with social jetlag in the North.

The discrepancy between biological and social rhythms known as social jetlag (SJL) is common in modern society and has a range of negative consequences for cognitive functioning, well-being and health. Social jetlag is typical for people with late chronotypes. As shown earlier, the prevalence of individuals with a late chronotype is higher among the residents of high latitudes. Therefore, a higher rate of detection of people with SJL should be expected in the North. In this study we assessed the detection rate of SJL among 62 young inhabitants of the European North of Russia (the Komi Republic), and the relationship between SJL, the circadian rhythm of the wrist temperature, and the cortisol awakening response (CAR). The detection rate of SJL was 65% among the people examined. A significant decrease in the amplitude (A) of circadian rhythm of wrist temperature: (ß = -0.34 (CI 95%: -0.66 to -0.33); F1,60 = 10.4; p < 0.0001; η(2) = 0.31), an increased incidence of depression: No-SJL = 4.5%; SJL = 17.5% (H = 4.84; p < 0.05), and a tendency for an increase in CAR was also observed in the SJL group. There were sex differences in sensitivity to SJL. Females with SJL but not males had higher global seasonality scores (ß = 0.51 (CI 95%: 0.21 to 0.81); F1,33 = 10.9; p < 0.002; η(2) =0.24), shorter sleep duration (ß = -0.52 (CI 95%: -0.82 to -0.22); F1,33 = 12.9; p < 0.001; η(2) = 0.28), worse sleep quality (ß = 0.39 (CI 95%: 0.07 to 0.72); F1,33 = 6.31; p < 0.017; η(2) = 0.16) and lower A of circadian rhythm of wrist temperature (ß = -0.18 (CI 95%: -0.55 to 0.18); F1,33 = 4.48; p < 0.043; η(2) = 0.13) compared with females without SJL. Thus, our data indicate that 40 of 62 participants of investigation had social jetlag. A decrease of the amplitude of the circadian rhythm of the wrist temperature appears to be an objective marker of SJL. Social jetlag had a strong negative impact on females but not on males.

Abrogation of the oral tolerance to ovalbumin in mice by citrus pectin.

OBJECTIVE: We studied the effects of dietary pectins (citrus pectin [CP] and apple pectin) on oral tolerance in mice. METHODS: Pectins (1 mg/d) were administered orally for 2 wk. Tolerance was induced with 20 mg of ovalbumin (OVA). Levels of serum antibodies (immunoglobulin [Ig] G, IgG1, IgG2a, IgE) and delayed type hypersensitivity response determined in footpad tests were measured after subcutaneous injection of OVA with complete Freund's adjuvant. Concentrations of immunoreactive OVA in blood were measured by enzyme-linked immunosorbent assay after feeding the animals 20 mg of OVA. Adhesion and cytokine production (tumor necrosis factor-alpha, interferon-gamma) were measured in peritoneal macrophages. RESULTS: Oral administration of CP was found to prevent the induction of immune hyporesponsiveness induced by OVA feeding. Animals fed OVA and CP were found to produce similar titers of antigen-specific serum IgG and levels of delayed type hypersensitivity response as those animals not fed OVA. CP increased levels of serum IgG1 and IgE. CP was found to enhance the penetration of immunogenic OVA into the serum. CP (1 mg/d) administered orally for 1 wk was also observed to enhance the adhesion and production of cytokines (tumor necrosis factor-alpha, interferon-gamma) in peritoneal macrophages. CONCLUSION: CP administered orally was shown to inhibit oral tolerance. Enhancement of protein antigen penetration to the blood and activation of macrophages were found to precede the inhibitory effect and appeared to mediate it.

Preventative antiinflammatory effect of potamogetonan, a pectin from the common pondweed Potamogeton natans L.

The pectic polysaccharide named potamogetonan (PN) was obtained using extraction of the leaves and stems of the common pondweed Potamogeton natans L. by an aqueous ammonium oxalate. The purified potamogetonan PN-300 was obtained using membrane ultrafiltration of PN and proved to be pectin with a molecular weight of 300 kDa. The capacity of potamogetonan PN-300 to prevent inflammation was assessed using a carrageenan paw edema test in mice. Oral administration of PN-300 24 h prior to induction of inflammation was found to reduce edema formation in a dose-related manner. The maximal effect of PN-300 was observed at 1 h after carrageenan injection (60% reduction of footpad swelling) and was comparable to that of indomethacin. The delayed edema (5 h) was less affected by pre-administration of PN-300 (33% reduction). PN-300 was found to improve the survival of mice subjected to a lethal dose of LPS. The anti-endotoxemic effect of PN-300 was shown to be mediated by decreased TNF-alpha and IL-1beta and increased IL-10 production.Thus, a pectin named potamogetonan PN-300 was isolated from P. natans and was shown to possess a preventive antiinflammatory effect following oral administration.