Interaction of fibroblasts and induced pluripotent stem cells with poly(vinyl alcohol)-based hydrogel substrates.

Induced pluripotent stem cells (iPSCs) provide a promising means of creating custom-tailored cell lines for cellular therapies. Their application in regenerative medicine, however, depends on the possibility that the maintenance and differentiation of cells and organs occur under defined conditions. One major component of stem cell culture systems is the substrate, where the cells must attach and proliferate. The present study aimed to investigate the putative cytotoxic effects of poly(vinyl alcohol) (PVA)-based matrices on the in vitro culture of mouse fetal fibroblasts. In addition, the PVA-based hydrogels were used to determine the capacity of bovine induced pluripotent stem cells (biPSCs) to adhere and proliferate on synthetic substrates. Our results show that both cell types interacted with the substrate and presented proliferation during culture. The biPSCs formed new colonies when cell suspensions were placed onto the hydrogel surface for culture. These results may represent a new characterized xeno-free clinical grade culture system to be widely applied in cell-based therapies.

Electrospinning and electrospray of bio-based and natural polymers for biomaterials development.

Over nearly 70 years, polymers have revolutionized the global economy, manufacturing and, mainly, the fields which require biocompatible materials, as food technology and packaging, controlled drug delivery, tissue engineering, regenerative medicine, wound dressing, anti-allergy textiles, and personal care. While new high-performance polymers were produced from fossil-based sources to meet the functional performance demands of new applications, Earth has been polluted by the operation of factories that released CO2 to the atmosphere during the production of synthetic polymers. At the same time, biocompatible and biodegradable alternatives were being required to meet specific needs of a range of applications. In this paper, we reviewed the use of electrospun/electrospray bio-based and natural polymers in the last ten years in food technology and smart packaging, food additives, antimicrobial packaging, enzyme immobilization, tissue engineering, drug delivery, wound dressing, anti-allergy fibers from milk, and faux meat. Also, we reviewed the use of ionic liquids and click chemistry techniques as alternatives for modification and functionalization of electrospun/electrospray bio-based and natural polymers.

Synthesis and characterization of acetylated amylose and development of inclusion complexes with rifampicin.

Amylose (AM) tends to form single helical inclusion complexes with suitable agents. These complexes are considered promising biomaterial carrier since the guest molecules can be released later, leading to many applications, especially in the pharmaceutical industry. Rifampicin (RIF) has long been recognized as an active drug against Mycobacterium tuberculosis, however, the administration of RIF in high dosages can originate unwanted side-effects. Due to the fact that the use of native amylose (AM) in the formation of complexes is limited by their low water solubility, it was acetylated with a medium degree of substitution (DS), allowing solubilizing (0.5gL-1) acetylated amylose (AMA) in water at neutral pH, in opposition to that observed with native amylose (trace solubility). The resulting acetylated amylose was characterized by means of Fourier Transform Infrared (FT-IR) spectroscopy and Scanning Electron Microscopy (SEM). FT-IR results indicated that the acetylation of anhydroglucose units of amylose corresponds to a low DS, whereas SEM results suggested that the smooth surfaces of amylose granules were changed into rougher surfaces after acetylation. Ultraviolet absorption spectroscopy (UV-vis) analysis confirmed the formation and allowed the quantification of both native (AM-RIF) and acetylated (AMA-RIF) amylose inclusion complexes. Their characterization in solution was performed by dynamic light scattering (DLS) and zeta potential (ZP) measurements. The average size of inclusion complexes as determined by DLS, ranged between 70 and 100nm. Besides, ZP analysis showed that both complexes are more stable in the presence of RIF. This study may lead to the development of an effective method for the preparation of amylose inclusion complexes, which is beneficial to their further application in drug delivery systems.

Designing Biomaterials for 3D Printing.

Three-dimensional (3D) printing is becoming an increasingly common technique to fabricate scaffolds and devices for tissue engineering applications. This is due to the potential of 3D printing to provide patient-specific designs, high structural complexity, rapid on-demand fabrication at a low-cost. One of the major bottlenecks that limits the widespread acceptance of 3D printing in biomanufacturing is the lack of diversity in "biomaterial inks". Printability of a biomaterial is determined by the printing technique. Although a wide range of biomaterial inks including polymers, ceramics, hydrogels and composites have been developed, the field is still struggling with processing of these materials into self-supporting devices with tunable mechanics, degradation, and bioactivity. This review aims to highlight the past and recent advances in biomaterial ink development and design considerations moving forward. A brief overview of 3D printing technologies focusing on ink design parameters is also included.

Gelatin and galactomannan-based scaffolds: Characterization and potential for tissue engineering applications.

In this work, we produced gelatin films containing different concentrations of galactomannan by casting solutions. The films were crosslinked by immersion in 30mM solution of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC). The crosslinking of gelatin-containing films was confirmed by the reduction of free amine band intensity (3400-3200cm(-1)) in the GEL IR, as well as by the evaluation of its behavior when immersed in phosphate-buffer solution. The crosslinking of galactomannan film was confirmed by the formation of new ether bonds, as observed by increasing intensity of the band at 1148cm(-1), and the reduction of OH band intensity (3600-3200cm(-1)). The presence of galactomannan and the crosslinking mediated by EDC were responsible to improve elasticity in the gelatin-based films. The samples did not show cytotoxicity during 24h or 48h. In addition, rat mesenchymal stem cells adhered to the films regardless of galactomannan concentration. The results indicated that the gelatin/galactomannan films are potential biomaterials for use as scaffolds for tissue engineering.

Poly (lactic acid)/chitosan fiber mats: investigation of effects of the support on lipase immobilization.

The greatest challenge for biotechnological processes is to have immobilized enzymes acting as good green catalysts with high reusability rates. In this work, we have produced electrospun fibers from poly (lactic acid)/chitosan blends. Further, we evaluated the influence of these materials as support for lipase immobilization. The PLA/chitosan fiber mats were composed by non-woven nanofibers, with diameters ranging from 200 nm to 1.3 µm. The solvent (TFA) as well as the chitosan addition influenced morphology, hydrophobicity and mechanical properties of PLA nanofibers. It was observed that even for lower concentration of lipase (5 U) higher enzyme activity retention was detected in the PLA/chitosan blends. In addition, a remarkable improvement of lipase activity on pure PLA fiber mat was verified, indicating that most of the enzymes were probably in their active form.

Structural analysis of chitosan hydrogels containing polymeric nanocapsules.

The incorporation of different concentrations of polymeric nanocapsule suspensions into chitosan hydrogels is proposed, in order to study the structure of a formulation with the properties of great tissue adhesion and controlled release of the nanoencapsulated drugs, represented here by capsaicinoids. The gels presented acceptable acid pH values and the nanoparticles were visually observed in the system. A transition from the micrometer to the nanometer scales suggested that the nanocapsules are initially agglomerated in the hydrogel. A sedimentation tendency of the nanocapsules in the system was observed and only physical interaction between the chitosan chains and polymeric nanocapsules was verified. The hydrogels, despite the presence of nanocapsules, presented shear-thinning properties and an elastic behavior under low and high frequencies, showing a very structured gel network. The observed variation in the elasticity of the hydrogels may arise from a decrease in the number of interactions and degree of entanglement between the chitosan chains, caused by the presence of nanoparticles.

Dynamic rheological properties of native and cross-linked gliadin proteins.

A comparison of cross-linked and native gliadin suspensions, with respect to the state of protein globular structure was carried out using small-angle X-ray scattering (SAXS), dynamic light scattering (DLS) and rheological analysis. Gliadin suspensions were also analyzed in the presence and absence of glycerol. DLS analysis showed that R(h) increased only with gliadin/EDC/NHS suspensions. However, Kratky plots revealed that gliadin and gliadin/L-cysteine maintained their globular shape even in absence or presence of glycerol. Rheological experiments revealed that gliadin and gliadin/L-cysteine suspension exhibited a similar profile with three main domains, and a sol-gel transition. Gliadin/EDC/NHS did not present any sol-gel transition, and this fact corroborates with DLS results and the hypothesis of lower protein-protein interaction, which are in agreement with G″ > G'.

A novel globular protein electrospun fiber mat with the addition of polysilsesquioxane.

The aim of this work has been to elaborate well defined gliadin nanofibers with incorporation of inorganic molecules, such as polyhedral oligomeric silsesquioxane (POSS). Nanofibers were obtained by electrospinning processing, controlling the relevant parameters such as tip-to-collector distance, voltage and feed rate. The fiber mats were characterized by SEM, confocal images, DSC, viscosity, FTIR and conductivimetry analysis. FTIR spectra showed characteristic absorption bands related to the presence of POSS-NH(2) within the matrices. SEM micrographs showed that gliadin fibers decreased their dimensions as the amount of POSS-NH(2) increased in the spinning solution. The electrical conductivity of gliadin solutions diminished as the concentration of POSS-NH(2) was increased. Besides, confocal micrographs revealed that POSS-NH(2) might be dispersed as nanocrystals into gliadin and gluten fibers. The dimension of gluten nanofibers was also affected by the POSS-NH(2) concentration, but conversely, this dependence was not proportional to the POSS-NH(2) amount. Somehow, the interaction between gliadin and POSS-NH(2) in aqueous TFE affected the solution viscosity and, as a consequence, higher jet instabilities and thinner fiber dimensions were obtained.