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Polysaccharide biomaterials have gained significant importance in the manufacture of nanoparticles used in colon-targeted drug delivery systems. These systems are a form of non-invasive oral therapy used in the treatment of various diseases. To achieve successful colonic delivery, the chemical, enzymatic and mucoadhesive barriers within the gastrointestinal (GI) tract must be analyzed. This will allow for the nanomaterials to cross these barriers and reach the colon. This review provides information on the development of nanoparticles made from various polysaccharides, which can overcome multiple barriers along the GI tract and affect encapsulation efficiency, drug protection, and release mechanisms upon arrival in the colon. Also, there is information disclosed about the size of the nanoparticles that are usually involved in the mechanisms of diffusion through the barriers in the GI tract, which may influence early drug degradation and release in the digestive tract.

The aim was to evaluate the potential of mucus-permeating nanoparticles for the oral administration of insulin. These nanocarriers, based on the coating of zein nanoparticles with a polymer conjugate containing PEG, displayed a size of 260 nm with a negative surface charge and an insulin payload of 77 μg/mg. In intestinal pig mucus, the diffusivity of these nanoparticles (PPA-NPs) was found to be 20-fold higher than bare nanoparticles (NPs). These results were in line with the biodistribution study in rats, in which NPs remained trapped in the mucus, whereas PPA-NPs were able to cross this layer and reach the epithelium surface. The therapeutic efficacy was evaluated in Caenorhabditis elegans grown under high glucose conditions. In this model, worms treated with insulin-loaded in PPA-NPs displayed a longer lifespan than those treated with insulin free or nanoencapsulated in NPs. This finding was associated with a significant reduction in the formation of reactive oxygen species (ROS) as well as an important decrease in the glucose and fat content in worms. These effects would be related with the mucus-permeating ability of PPA-NPs that would facilitate the passage through the intestinal peritrophic-like dense layer of worms (similar to mucus) and, thus, the absorption of insulin.

The aim was to evaluate the potential of nanocarriers, based on the coating of zein nanoparticles (ZNP) with a Gantrez® AN-PEG conjugate (GP), for the oral delivery of insulin. ZNP-GP displayed less negative surface charge and a 14-fold higher diffusion coefficient in pig intestinal mucus than ZNP. Both nanoparticles showed a spherical shape and an insulin load of 77.5 µg/mg. Under simulated gastric conditions, ZNP-GP released significantly lower amount of insulin than ZNP, while under simulated intestinal conditions, both types of nanoparticles displayed similar behaviour. In Caenorhabditis elegans wild-type N2, grown under high glucose conditions, insulin treatments reduced glucose and fat accumulation without altering the growth rate, the worm length, or the pumping rate. The effect was significantly greater (p

Resumen Objetivo Optimizar el radiomarcaje con 99mTc y 67Ga de nanoparticulas de albumina recubiertas con 4 polimeros sinteticos distintos y evaluar su estabilidad in vivo e in vitro, asi como su biodistribucion in vivo tras su administracion intravenosa. Material y metodos Las nanoparticulas se prepararon empleando albumina y albumina modificada con NOTA mediante el metodo de desolvatacion y se recubrieron con 4 polimeros distintos; HPMC, GMN2, GPM2 y GTM2. Se purificaron, liofilizaron y caracterizaron. El marcaje con 99mTc se realizo con 74 MBq de pertecnetato [99mTc] sodico previamente reducido con una disolucion acida de cloruro de estano a diferentes concentraciones (0,003; 0,005; 0,007; 0,01; 0,05 y 0,1 mg/ml), a distintos tiempos (5, 10, 15, 30 y 60 min) y temperaturas (temperatura ambiente, 40 °C y 60 °C). El marcaje con 67Ga se llevo a cabo mediante incubacion de las nanoparticulas con 37 MBq de cloruro de 67Ga (obtenido a partir de citrato de 67Ga comercial) a distintos tiempos (10 y 30 min) y temperaturas (temperatura ambiente, 30 °C y 60 °C) y posterior purificacion con microconcentradores. La pureza radioquimica de ambos marcajes se evaluo mediante TLC. Se llevaron a cabo estudios de estabilidad de las nanoparticulas marcadas en suero fisiologico y plasma sanguineo. Los estudios de biodistribucion de las nanoparticulas recubiertas con el polimero GPM2 se llevaron a cabo en ratas Wistar tras la administracion intravenosa de las nanoparticulas. Se realizaron animales control con pertecnetato [99mTc] sodico y cloruro de 67Ga. Posteriormente, los animales fueron sacrificados y se midio la actividad de los organos en un contador gamma. Resultados El marcaje con 99mTc se llevo a cabo de forma optima con una concentracion de estano de 0,007 mg/ml para las nanoparticulas GPM2 y de 0,005 mg/ml para el resto de formulaciones, con un tiempo de marcaje de 10 min y a temperatura ambiente. En el caso del 67Ga el marcaje se optimizo a 30 °C de temperatura y 30 min de incubacion. En ambos casos, la pureza radioquimica obtenida fue superior al 97%. Las nanoparticulas presentaron una elevada estabilidad in vitro pasadas las 48 h del marcaje (70% las nanoparticulas marcadas con 99mTc y 90% las marcadas con 67Ga). Los estudios de biodistribucion de las nanoparticulas [99mTc]-GPM2 y [67Ga]-NOTA-GPM2 mostraron una elevada acumulacion de actividad en el higado tanto a las 2 h como a las 24 h de la administracion intravenosa. Conclusion El procedimiento de marcaje con 99mTc y 67Ga de nanoparticulas de albumina y albumina modificada con NOTA permite la obtencion de nanoparticulas con elevados rendimientos de marcaje y una adecuada estabilidad in vitro, permitiendo su utilizacion para la realizacion de estudios in vivo.

The aim of this work was to evaluate oral nanocarriers, prepared from zein nanoparticles coated with a poly(anhydride)-thiamine conjugate (GT), for the delivery of insulin. Nanoparticles displayed a size of 250 nm with a negative surface charge, and an insulin loading of 80 μg/mg. Under simulated gastric conditions, GT-coated nanoparticles released a significantly lower amount of insulin than bare ones; whereas in simulated intestinal conditions, both types of nanoparticles displayed a similar behavior. The effect of insulin on the lipid metabolism of C. elegans under high glucose conditions, characterized by a reduction of the fat content, was also investigated. The effect was significantly higher for the nanoencapsulated forms of insulin than for the free protein (p < 0.001). This effect was two times higher for GT-coated nanoparticles than for bare ones. In rats, the hypoglycemic effect and the pharmacokinetic profile of insulin-loaded nanoparticles orally administered (50 IU/kg) were evaluated. The glycemia of animals slowly decreased reaching a minimum 6-10-h post-administration, with a maximum decrease of about 60%. The pharmacological availability of nanoencapsulated insulin was 13.5%. In serum, nanoparticles provided a maximum of insulin 4-h post-administration, and its relative oral bioavailability was 5.2% (compared with a sc formulation of insulin). Graphical abstract.

Arabinoxylans (AX) microspheres with different insulin/AX mass ratio were prepared by formation of phenoxy radical issued from the ferulic acid by enzymatic oxidation (entrapped in situ of insulin). Phenolic acid content and FT-IR spectrum of unloaded and insulin-loaded AX microspheres revealed that the phenoxy radical issued from the ferulic acid by enzymatic oxidation did not interact covalently with insulin. The microspheres showed a spherical shape, smooth surface and an average diameter of particles of 320 μm. In vitro control release found that AX microspheres minimized the insulin loss in the upper GI tract, retaining high percentage (~75%) of insulin in its matrix. The stability of the secondary structure of insulin was studied by dichroism circular (CD). The CD spectra of insulin released from AX microspheres did not change according to the insulin/AX mass ratio of the microsphere. Significant hypoglycemic effects with improved insulin-relative bioavailability tested on an in vivo murine model revealed the efficacy of these enzymatically cross-linked arabinoxylans microspheres as a new oral insulin carrier.

Thiamine-coated nanoparticles were prepared by two different preparative methods and evaluated to compare their mucus-penetrating properties and fate in vivo. The first method of preparation consisted of surface modification of freshly poly(anhydride) nanoparticles (NP) by simple incubation with thiamine (T-NPA). The second procedure focused on the preparation and characterization of a new polymeric conjugate between the poly(anhydride) backbone and thiamine prior the nanoparticle formation (T-NPB). The resulting nanoparticles displayed comparable sizes (about 200 nm) and slightly negative surface charges. For T-NPA, the amount of thiamine associated to the surface of the nanoparticles was 15 μg/mg. For in vivo studies, nanoparticles were labelled with either 99mTc or Lumogen® Red. T-NPA and T-NPB moved faster from the stomach to the small intestine than naked nanoparticles. Two hours post-administration, for T-NPA and T-NPB, >30% of the given dose was found in close contact with the intestinal mucosa, compared with a 13.5% for NP. Interestingly, both types of thiamine-coated nanoparticles showed a greater ability to cross the mucus layer and interact with the surface of the intestinal epithelium than NP, which remained adhered in the mucus layer. Four hours post-administration, around 35% of T-NPA and T-NPB were localized in the ileum of animals. Overall, both preparative processes yielded thiamine decorated carriers with similar physico-chemical and biodistribution properties, increasing the versatility of these nanocarriers as oral delivery systems for a number of biologically active compounds.

The aim was to evaluate the potential of nanocarriers, based on the coating of zein nanoparticles (ZNP) with a Gantrez® AN-PEG conjugate (GP), for the oral delivery of insulin. ZNP-GP displayed less negative surface charge and a 14-fold higher diffusion coefficient in pig intestinal mucus than ZNP. Both nanoparticles showed a spherical shape and an insulin load of 77.5 µg/mg. Under simulated gastric conditions, ZNP-GP released significantly lower amount of insulin than ZNP, while under simulated intestinal conditions, both types of nanoparticles displayed similar behaviour. In Caenorhabditis elegans wild-type N2, grown under high glucose conditions, insulin treatments reduced glucose and fat accumulation without altering the growth rate, the worm length, or the pumping rate. The effect was significantly greater (p 0.001) when insulin was nanoencapsulated in ZNP-GP compared with that encapsulated in ZNP or formulated in solution. This would be related to the highest capability of ZNP-GP to diffuse in the dense peritrophic-like layer covering intestinal cells in worms. In daf-2 mutants, the effect on fat and glucose reduction by insulin treatment was suppressed, indicating a DAF-2 dependent mechanism. In summary, ZNP-GP is a promising platform that may offer new opportunities for the oral delivery of insulin and other therapeutic proteins.

Device-Associated Healthcare-Associated Infections (DA-HAI) are a major threat to public health worldwide since they are associated with increased hospital stays, morbidity, mortality, financial burden, and hospital overload. A strategy to combat DA-HAI involves the use of medical devices endowed with surfaces that can kill or repel pathogens and prevent biofilm formation. We aimed to develop low-toxic protease-resistant anti-biofilm surfaces that can sensitize drug-resistant bacteria to sub-inhibitory concentrations of antibiotics. To this end, we hypothesized that polymyxin B nonapeptide (PMBN) could retain its antibiotic-enhancing potential upon immobilization on a biocompatible polymer, such as silicone. The ability of PMBN-coated silicone to sensitize a multidrug-resistant clinical isolate of Pseudomonas aeruginosa (strain Ps4) to antibiotics and block biofilm for- mation was assessed by viable counting, confocal microscopy and safranin uptake. These assays demonstrated that covalently immobilized PMBN enhances not only antibiotics added exogenously but also those incorporated into the functionalized coating. As a result, the functionalized surface exerted a potent bactericidal activity that precluded biofilm formation. PMBN-coated silicone displayed a high level of stability and very low cytotoxicity and hemolytic activity in the presence of antibiotics. We demonstrated for the first time that an antibiotic enhancer can retain its activity when covalently attached to a solid surface. These findings may be applied to the development of medical devices resistant to biofilm formation

The chapter provides an overview of the different strategies, based on nanotechnology, to overcome one of the main barriers related to the mucosal delivery of biologically active compounds. Therapeutic nanocarriers are largely trapped by the protective mucus layer, limiting their residence time on epithelial surfaces and, therefore, reducing the possibilities for drug absorption or action. Development of mucus-penetrating particles provides a promising tool for overcoming this barrier. For this purpose, different strategies may be envisaged, including a combination of nanocarriers with mucolytic compounds or their coating with hydrophilic agents in order to minimize adhesive interactions with mucus components. Another possibility would be the use of a biomimetic approach similar to those developed by bacteria and virus to reach the epithelium before entry into host mucosal cells.

The aim was to produce PEG-coated nanoparticles (NP-PEG), with mucus-permeating properties, for oral drug delivery purposes by using simple procedures and regulatory-approved compounds in order to facilitate a potential clinical development. For this purpose, zein nanoparticles were prepared by desolvation and, then, coated by incubation with PEG 35,000. The resulting nanocarriers displayed a mean size of about 200 nm and a negative zeta potential. The presence of PEG on the surface of nanoparticles was evidenced by electron microscopy and confirmed by FTIR analysis. Likely, the hydrophobic surface of zein nanoparticles (NP) was significantly reduce by their coating with PEG. This increase of the hydrophilicity of PEG-coated nanoparticles was associated with an important increase of their mobility in pig intestinal mucus. In laboratory animals, NP-PEG (fluorescently labelled with Lumogen® Red 305) displayed a different behavior when compared with bare nanoparticles. After oral administration, NP appeared to be trapped in the mucus mesh, whereas NP-PEG were capable of crossing the protective mucus layer and reach the epithelium. Finally, PEG-coated zein nanoparticles, prepared by a simple and reproducible method without employing reactive reagents, may be adequate carriers for promoting the oral bioavailability of biomacromolecules and other biologically active compounds with low permeability properties.

Proteins represent a group of biopolymers with interesting properties to be employed as raw materials in the preparation of nanoparticles for drug delivery purposes. Due to the inherent properties of proteins (i.e., biodegradability, amphiphilic properties, etc.) the resulting nanoparticles can be considered as versatility platforms for a variety of applications. Moreover, some proteins possess a GRAS (Generally Recognized as Safe) status or are considered as excipients by different Regulatory Agencies. As result of this, the resulting nanoparticles and potential translation to clinic would be facilitated, compared to other materials (i.e., polymers). This review is focused on the main proteins employed in the preparation of nanoparticles as well as the procedures permitting their transformation into nanoparticles able of accommodating a high variety of bioactive compounds and drugs. Moreover, the review also provides examples of application of nanoparticles prepared from albumins, globulins, prolamins or macromolecules derived from proteins.

Feruloylated arabinoxylans were obtained from nixtamalized maize bran under alkaline conditions (0.5 N NaOH) at different times (2 h, 4 h and 6 h). They were analyzed for neutral sugars composition, dietary fiber and ferulic acids content, as well as the antioxidant capacity, to establish if they can be considered as soluble antioxidant dietary fiber. The yields of the arabinoxylans following alkaline extraction treatments were 4.89%, 8.23% and 7.17% for 2 h, 4 h and 6 h, respectively. The purity of arabinoxylans ranged from 55.58 to 61.16%, while arabinose to xylose (Ara/Xyl) ratio ranged from 0.82 to 0.87 which indicated that all arabinoxylans had a moderately branched structure. The soluble dietary fiber accounted for more than 85% of the chemical composition of feruloylated arabinoxylans. Monomeric and oligomeric forms of ferulic acid were influenced by the alkali extraction time. The monomeric form was the main phenolic acid in feruloylated arabinoxylans (77.05–86.97%), followed by dimers (11.57–14.20%), and trimer (0.93–9.36%). Total phenols ranged from 9.01 to 6.48 mg FAE/g, while antioxidant capacity ranged from 29.49 to 31.69 µmol TE/g, 16.60 to 21.27 µmol TE/g, 39.23 to 58.33 µmol TE/g and 17.03 to 60.65 µmol TE/g in DPPH, ABTS, FRAP and ORAC methods, respectively. The phenol content and antioxidant capacity were in the order: 2 h extract > 4 h extract > 6 h extract and in accordance to the ferulic acid content. The results indicated that alkali extracted feruloylated arabinoxylans obtained from nixtamalized maize bran byproduct are synonymous with soluble antioxidant dietary fiber.

This study aimed to investigate the effect of arabinoxylans (AX) partial de-esterification with feruloyl esterase on the polysaccharide conformational behavior, topographical features, and antioxidant activity. After enzyme treatment, the ferulic acid (FA) content in AX was reduced from 7.30 to 5.48 µg FA/mg polysaccharide, and the molecule registered a small reduction in radius of gyration (RG), hydrodynamic radius (Rh), characteristic ratio (C∞), and persistence length (q). A slight decrease in α and a small increase in K constants in the Mark–Houwink–Sakurada equation for partially de-esterified AX (FAX) suggested a reduction in molecule structural rigidity and a more expanded coil conformation, respectively, in relation to AX. Fourier transform infrared spectroscopy spectra of AX and FAX presented a pattern characteristic for this polysaccharide. Atomic force microscopy topographic analysis of FAX showed a more regular surface without larger hollows in relation to AX. The antioxidant activity of FAX, compared to AX, was reduced by 30 and 41% using both 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS+) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) methods, respectively. These results suggest that feruloyl esterase treatment of AX could offer a strategy to tailor AX chains conformation, morphological features, and antioxidant activity, impacting the development of advanced biomaterials for biomedical and pharmaceutical applications.

Arabinoxylans (AX) gels at 4% (w/v) were prepared using laccase (LAX gels) or peroxidase (PAX gels), and their cross-linking, rheological, structural, and spectroscopic characteristics were investigated. LAX gels presented lower amount of 5,5′-diferulic acid (11%), smaller mesh size (128 nm), and higher hardness (37 N) and elasticity (430 Pa) than the PAX gels (28%, 197 nm, 7 N, and 120 Pa, respectively). Microscopy of the LAX gels showed linked strands, while the system was less connected in the PAX gels. The Raman band at 2895 cm(−1) of the LAX and PAX gels was less intense, indicating enhanced hydrogen bonding compared to that of AX. This decrease was less dramatic for the PAX gels. The greater content of 5,5′-diferulic acid in PAX gels could favor intrachain bonds, affecting their rheological, structural, and spectroscopic characteristics. Laccase may be a better option than peroxidase for AX gelation intended for food and biotechnological applications.

The purpose of this investigation was to extract ferulated arabinoxylans (AX) from dried distillers’ grains with solubles (DDGS) plus to investigate their capability to form covalently cross-linked nanoparticles. AX registered 7.3 µg of ferulic acid/mg polysaccharide and molecular weight and intrinsic viscosity of 661 kDa and 149 mL/g, correspondingly. Fourier transform infrared spectroscopy (FTIR) was used to confirm the identity of this polysaccharide. AX formed laccase induced covalent gels at 1% (w/v), which registered an elastic modulus of 224 Pa and a content of FA dimers of 1.5 µg/mg polysaccharide. Scanning electron microscopy pictures of AX gels exhibited a microstructure resembling a rough honeycomb. AX formed covalently cross-linked nanoparticles (NAX) by coaxial electrospray. The average hydrodynamic diameter of NAX determined by dynamic light scattering was 328 nm. NAX presented a spherical and regular shape by transmission electron microscopy analysis. NAX may be an attractive material for pharmaceutical and biomedical applications and an option in sustainable DDGS use.

Due to their porous structure, aqueous environment and dietary fiber nature arabinoxylan (AX) gels could have potential applications for colon-specific therapeutic molecule delivery. In addition, prebiotic and health related effects of AX have been previously demonstrated. It has been also reported that cross-linked AX can be degraded by bacteria from the intestinal microbiota. However, AX gels have not been abundantly studied as carrier systems and there is no information available concerning their capability to entrap cells. In this regard, probiotic bacteria such as Bifidobacterium longum have been the focus of intense research activity lately. The objective of this research was to investigate the entrapment of probiotic B. longum in AX gels. AX solution at 2% (w/v) containing B. longum (1 × 107 CFU/cm) formed gels induced by laccase as cross-linking agent. The entrapment of B. longum decreased gel elasticity from 31 to 23 Pa, probably by affecting the physical interactions taking place between WEAX chains. Images of AX gels containing B. longum viewed under a scanning electron microscope show the gel network with the bacterial cells entrapped inside. The microstructure of these gels resembles that of an imperfect honeycomb. The results suggest that AX gels can be potential candidates for the entrapment of probiotics.

The molecular identity, molecular weight distribution, and microstructure of arabinoxylans from nixtamalized (N-MBAX) or non-nixtamalized (MBAX) maize bran were investigated and correlated to their gelling capability and the gels’ structural and rheological properties. N-MBAX and MBAX presented Fourier transform infra-red (FT-IR) spectra typical of arabinoxylans. A low-molecular-weight fraction of arabinoxylans was present in MBAX but not in N-MBAX. Scanning electron microscopy (SEM) analysis showed that N-MBAX and MBAX present a rough and smooth surface topography, respectively. N-MBAX and MBAX gels were prepared by laccase oxidative cross-linking. N-MBAX and MBAX gels at 6% (w/v) presented an average pore size of 108 and 134 nm and elasticity values of 328 and 62 Pa, respectively. In SEM images, N-MBAX gels appear as a mix of sheets and rigid plates, while MBAX gels present an irregular honeycomb structure. These results indicate that nixtamalization process modify the molecular weight distribution and ...

International audience; Arabinoxylan gels with different cross-linking densities, swelling ratios, and rheological properties were obtained by increasing the concentration of arabinoxylan from 4 to 6% (w/v) during oxidative gelation by laccase. The degradation of these covalently cross-linked gels by a mixture of two Bifidobacterium strains (Bifidobacterium longum and Bifidobacterium adolescentis) was investigated. The kinetics of the evolution of structural morphology of the arabinoxylan gel, the carbohydrate utilization profiles and the bacterial production of short-acid fatty acid (SCFA) were measured. Scanning electron microscopy analysis of the degraded gels showed multiple cavity structures resulting from the bacterial action. The total SCFA decreased when the degree of cross-linking increased in the gels. A slower fermentation of arabinoxylan chains was obtained for arabinoxylan gels with more dense network structures. These results suggest that the differences in the structural features and properties studied in this work affect the degradation time of the arabinoxylan gels.

IATE Axe 1: Fractionnement des Agro ressources : bases structurales et physicochimiques ; procédés de broyage, extraction et de séparationIATE Axe 2: Structuration sous contraintes des agropolymères et réactivité des poudres; The oxidative gelation of maize bran arabinoxylans (MBAX) using a peroxidase/H2O2 system as a free radical-generating agent was investigated. The peroxidase/H2O2 system led to the formation of dimers and trimer of ferulic acid as covalent cross-link structures in the MBAX network. MBAX gels at 4% (w/v) presented a storage modulus of 180 Pa. The structural parameters of MBAX gels were calculated from swelling experiments. MBAX gels presented a molecular weight between two cross-links (Mc), a cross-linking density (ρc) and a mesh size (x) of 49 × 103 g/mol, 30 × 10−6 mol/cm3 and 193 nm, respectively.

Water-soluble feruloylated arabinoxylans were extracted from maize processing waste water (nejayote) generated from tortilla-making industries. Nejayote arabinoxylans (NAX) presented a ferulic acid content of 0.23 μg/mg, an arabinose to xylose ratio (A/X) of 0.65, an intrinsic viscosity, [ η ], of 183 ml/g and a molecular weight (Mw) of 60 kDa. Laccase-induced gels were obtained from 4% (w/v) NAX solution while, at lower concentrations, no gelation was observed. Laccase covalent cross-linking of NAX led to the formation of diferulic (di-FA) and triferulic (tri-FA) acid structures. 4% (w/v) NAX gel presented di-FA and tri-FA contents of 0.02 and 0.01 μg/mg NAX, respectively, and a G ′ value of 2 Pa. Recuperation of this gum from a low-value maize by-product could represent a commercial advantage over other gums commonly used in the food industry.

Ferulatedarabinoxylans (FAX) present antioxidant properties which appear to be correlated with their ferulic acid (FA) content. The aim of this research was to investigate the effect of oxidative coupling of FA on the antioxidant properties of FAX microspheres.

Pectin was acid-extracted from low quality ‘Golden Delicious’ apple fruit, yielding 16% (w pectin/w apple fruit). Composition and some of its physicochemical and functional properties were assessed. The pectin fraction presented a galacturonic acid content of 65% (w/w), an esterification degree of 57%, an intrinsic viscosity, [η], of 307 ml/g and a molecular weight (Mw) of 112 kDa. Pectin gels were obtained in 60% (w/v) fructose and pH 2.7. Pectin gels at 2.0% and 3.0% (w/v) presented hardness values of 10.2 and 20.4 g after 12 h at 4 °C. The gel hardness was greatly affected by aging (20% and 25% decrease in 48 h for gels at 2% and 3%, respectively). The results attained suggest the use of this gum as a potential texturing agent for the food industry.

The aim of this research was to study the structural and textural characteristics of maize bran arabinoxylan (MBAX) microspheres. The laccase-induced cross-linking process was monitored by storage (G') and loss (G'') moduli changes in a 4% (w/v) MBAX solution. The G' and G'' values at the plateau region were 215 and 4 Pa, respectively. After gelation, the content of ferulic acid dimers decreased from 0.135 to 0.03 µg/mg MBAX, suggesting the formation of ferulated structures unreleased by mild alkaline hydrolysis. MBAX microspheres presented an average diameter of 531 µm and a swelling ratio value (q) of 18 g water/g MBAX. The structural parameters of MBAX microspheres were calculated from equilibrium swelling experiments, presenting an average mesh size of 52 nm. Microstructure and textural properties of dried MBAX microspheres were studied by scanning electron microscopy and nitrogen adsorption/desorption isotherms, respectively, showing a heterogeneous mesoporous and macroporous structure throughout the network.

Arabinoxylan gels are receiving increasing attention as oral delivery systems of biomolecules for therapeutic purposes. The aim of this research was to evaluate arabinoxylan gels as an oral delivery system for insulin, representing a painless therapy for diabetics. Gels at two concentrations of arabinoxylan were prepared (2.5 and 3.5 % w/v). One concentration of insulin (0.05 % w/v) entrapped in the arabinoxylan gels was investigated. At the end of gelation elasticity (G’) values were 11 and 20 for gels at 2.5 and 3.5% (w/v) in arabinoxylan, respectively. The presence of insulin in the gels did not affect the values of G’. The apparent diffusion coefficient for insulin decreased from 1.30 x 10-7 to 1.09 x 10-7 cm2/s when the concentration of arabinoxylan in the gel increased from 2.5 to 3.5% (w/v). The percentage of proteolysis for insulin entrapped in the gels at 2.5 and 3.5% in arabinoxylan (w/v) were 35 and 17%, respectively, in relation to 100% hydrolysis of insulin in solution. Results indicate that arabinoxylan gels could be potential candidates as oral delivery systems for insulin.

Arabinoxylans are polysaccharides constituted of a linear backbone of xylose in which arabinose substituents are attached, some ferulic acid esterifies arabinose. Arabinoxylan can form covalent gels by oxidative coupling of ferulic acid. Arabinoxylan gels could have potential applications for colon-specific biomolecules delivery due to their macroporous structure, and their aqueous environment and their dietary fiber nature. Lycopene has received increasing attention for its possible role in the prevention of colon cancer. It has been previously reported that arabinoxylan gels could be formed in presence of lycopene with no detriment on the lycopene antioxidant activity. The objective of this research was to investigate the in vitro degradation of arabinoxylan gels (AX gels) by two human colon bacterial species (Bacteroides ovatus and Bifidobacterium longum). Bacterial counts (CFU ml-1) and metabolic heat production (p) followed a similar pattern with a high response during the first 24 h at 37 °C. A regression model related CFU ml-1 and p (r2= 0.98). These results show that AX gels could be carriers for lycopene delivery in colon due structure degradation by gut microbiota.

The laccase induced gelation of maize bran arabinoxylans at 2.5% (w/v) in the presence of insulin or beta-lactoglobulin at 0.1% (w/v) was investigated. Insulin and beta-lacto-globulin did not modify either the gel elasticity (9 Pa) or the cross-links content (0.03 and 0.015 microg di- and triferulic acids/mg arabinoxylan, respectively). The protein release capability of the gel was also investigated. The rate of protein release from gels was dependent on the protein molecular weight. The apparent diffusion coefficient was 0.99 x 10(-7) and 0.79 x 10(-7) cm(2)/s for insulin (5 kDa) and beta-lactoglobulin (18 kDa), respectively. The results suggest that maize bran arabinoxylan gels can be potential candidates for the controlled release of proteins.