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Disinfection of electrospun materials is commonly carried out by ethanol (EtOH) soaking. However, in the literature no systematic investigation on the effect of EtOH disinfection on scaffold properties is available. In this study electrospun poly( l -lactic acid) (PLLA) scaffolds were differently treated in EtOH and changes of fiber morphology, fiber surface topography and scaffold thermo-mechanical properties were evaluated. It was found that EtOH induced the formation of an amount of crystal phase, in the initially amorphous fibers, which depends on EtOH grade, soaking time and temperature. Completely amorphous PLLA (a-PLLA) and semicrystalline PLLA (sc-PLLA) scaffolds were produced by applying different EtOH treatments to as-spun PLLA scaffold. Compared to a-PLLA, sc-PLLA was stiffer and composed of fibers with rougher surface. Cell culture performed by using permanent cell line H9c2 demonstrated that changes of scaffold properties determined a different cell response, in particular in the expression of proteins correlated to cell motility and cell adhesion.

Biomedical applications of electrospun porous non-woven mats require a particular attention towards fibre surface properties, given the high surface area to volume ratio associated with these kind of structures. Ad hoc modication of the surface properties of electrospun fibres, while maintaining the bulk properties of the constituting material, is crucial in determining their use and it is among important targets of the scientific community. In this work we use Surface Initiated Atom Transfer Radical Polymerization (SI-ATRP) to modify the surface of electrospun Poly(L)lactic cid (PLLA) fibers. In particular, electrospun fibers grafted with poly(glycerol monomethacrylate), poly(GMMA) and poly(2-(diethylamino)ethyl methacrylate), poly(DEAEMA), brushes were obtained with the aim to confer, respectively, non-fouling and antibacterial properties to PLLA fibres.

Electrospun (ES) materials are considered highly promising scaffolds for tissue engineering given their particular fibrous morphology that resembles the fibrous component of tissue extracellular matrix. ES scaffolds made of commercial bioresorbable polyesters can be dramatically affected by commonly employed sterilization methods (e.g. autoclaving, ethylene oxide, -rays), thus they are usually disinfected with ethanol (EtOH) before being used in contact with a biological environment. However, even if less extensively, also EtOH disinfection might affect ES scaffold morphology and, consequently, the response of cells cultured onto them. This work aims at investigating the effect of EtOH sterilization on poly(L)lactic acid (PLLA) ES scaffold and in particular on its phase morphology (amorphous to crystalline ratio). The morphological changes of PLLA non-woven mats treated at different temperatures by using EtOH solutions with different concentration, were compared. Moreover, the behaviour of H9c2 cardiac cells seeded onto PLLA scaffolds treated with EtOH was investigated.

The basic approach to bone tissue engineering involves the development of highly porous biodegradable 3D-scaffolds, with interconnected pore network structure for cellular in-growth, revascularization, adequate nutrition and oxygen supply. Electrospinning is a simple and cost-effective technique that enables to fabricate scaffolds, both from synthetic and natural polymers, mimicking the three-dimensional nano-scaled features of ECM. Synthetic bioresorbable polymers provide structural functionalities to the scaffold. On the other hand, natural polymers display unique bioactive properties and excellent cellular affinity. In this work we developed new electrospun scaffolds made up of poly(L)lactic acid (PLLA) fibers and Type A gelatin fibers with the aim of combining the bioactivity of gelatin together with the structural stability of PLLA in a unique scaffold. Scaffolds were prepared by concomitantly electrospinning a PLLA solution and a gelatin solution and chemical-physical properties were evaluated and related to scaffold structure and composition.

Medical devices and tissue engineered constructs may induce an inflammatory reaction – termed foreign body reaction (FBR) – after their in vivo implantation. Despite recent advances in material science and tissue engineering, current knowledge of the inflammatory mechanisms associated with FBR remains scanty. Electrospinning has been recognized as a scaffold fabrication technique with great potential. From a wide range of polymer solutions and melts, this technique produces continuous polymeric fibers with diameters ranging from a few nanometers to tens of microns. The possibility of controlling fiber morphology and fiber deposition pattern makes electrospinning a powerful method to fabricate tissue engineered scaffolds with a defined micro/nano-architecture in terms of fiber size and fiber orientation. Accordingly, lectrospun substrates have been used for a wide range of tissue engineering applications including neural, ardiovascular, bone, and skin tissue engineering. Despite the increased interest in electrospinning, the potential effects of electrospun scaffolds on the immune system have not been fully examined. Macrophage activation can be modulated by biomaterial topography according to the biological scale (micrometric and nanometric range). In this study we investigated the effect of fiber diameter and fiber alignment of electrospun poly(L-lactic) (PLLA) scaffolds on macrophage RAW 264.7 activation and secretion of proinflammatory cytokines and chemokines at 24 h and 7 days.

Macrophage activation can be modulated by biomaterial topography according to the biological scale (micrometric and nanometric range). In this study, we investigated the effect of fiber diameter and fiber alignment of electrospun poly(L-lactic) (PLLA) scaffolds on macrophage RAW 264.7 activation and secretion of proinflammatory cytokines and chemokines at 24 h and 7 days. Macrophages were cultured on four different types of fibrous PLLA scaffold (aligned microfibers, aligned nanofibers, random microfibers, and random nanofibers) and on PLLA film (used as a reference). Substrate topography was found to influence the immune response activated by macrophages, especially in the early inflammation stage. Secretion of proinflammatory molecules by macrophage cells was chiefly dependent on fiber diameter. In particular, nanofibrous PLLA scaffolds minimized the inflammatory response when compared with films and microfibrous scaffolds. The histological evaluation demonstrated a higher number of foreign body giant cells on the PLLA film than on the micro- and nanofibrous scaffolds. In summary, our results indicate that the diameter of electrospun PLLA fibers, rather than fiber alignment, plays a relevant role in influencing in vitro macrophage activation and secretion of proinflammatory molecules.

A recent advance in tissue engineering is the development of biomimetic nanofiber for tissue regeneration. Using electrospinning nanotechnology, fibrous scaffolds can be fabricated in a controllable manner from solutions of many biocompatible polymers; the final result is a scaffold displaying a 3D architecture similar to that seen in the extracellular matrix natural microenvironment. By electrospinning it is possible to produce random or aligned nanofiber mats able to influence cell behaviour that can be potentially useful in tailored clinical applications. However, in the context of heart tissue repair, few studies are reported and it is not yet established whether these biomimetic nanofiber scaffolds nay have suitable properties for promoting cell adhesion, proliferation and migration. The aim of this work is to produce electrospun nanostructured polymeric bioresorbable and biocompatible scaffolds using poly-L-lactic acid (PLLA) and to investigate the cell/scaffold interactions using H9c2 myoblast cells derived from embryonic rat heart.

Electrospinning is a very versatile technology that enables production of nanofibrous structures with morphology and fiber diameter dimensionally comparable to that of the extracellular matrix in natural tissues. For this reason electrospun scaffolds are believed to provide a better biomimetic environment than other types of porous tissue engineering scaffolds. Electrospun scaffolds offer an ideal support for cell attachment, migration, proliferation and differentiation. Non-woven mats obtained through the common electrospinning set-up, are usually characterized by random fiber orientation. A suitable design of the experimental apparatus and careful tuning of the processing parameters yield nanofibres with desired diameter and precise alignment. Nanofiber mats with specific fiber patterning may also be fabricated. This aspect is important because it is well known that the micro/nano-architecture of the scaffold may affect cell behaviour and in particular cell differentiation. The scientific community is still divided on the controversial aspect of whether or not, cells can colonize the inner regions of an electrospun mat when in vitro growth of new tissue is pursued. Many strategies have been followed by researchers to overcome the apparent limitation of efficient cell ingrowth, that is commonly attributed to too small pore size in electrospun scaffolds.In this work bioresorbable polymer scaffolds for tissue engineering are fabricated by electrospinning technology integrated with a flexible mechatronic equipment, that allows controlled and reproducible production of scaffolds with 3-D architecture tailored to specific applications. In particular, an ‘ad hoc’ collecting device allows fabrication of variously oriented and patterned fibrous structures. Composite scaffolds can also be produced by instrument implementation with multiple spinning devices. Results of in vitro cell cultures on such scaffolds provide evidence of cell colonization and penetration. In most tissue engineering applications the scaffold supporting cell growth should be bioresorbable by the host organism. Biodegradable electrospun scaffolds are made of hydrolysable polymers and must be properly designed in order to obtain bio-resorption rates tuned to the rate of tissue regeneration. In addition to their potential in tissue reconstruction, bioabsorbable nanofibrous scaffolds may also be efficiently used as drug dispensing systems for the release of bioactive molecules, such as growth factors. Electrospinning technology is very promising for the incorporation of biomolecules into fibers, thus obtaining functionalized scaffolds. The results of this work show that growth factors can be incorporated in a fiber mat during the electrospinning process without loss of bio-activity, as demonstrated by cell response upon growth factor release in the culture medium. This result confirms the versatility of the electrospinning technique.