Masaya Kotaki

ALIGNED BIODEGRADABLE NANOFIBROUS STRUCTURE: A POTENTIAL SCAFFOLD FOR BLOOD VESSEL ENGINEERING

A unique biodegradable nanofibrous structure, aligned poly(L-lactid-co-epsilon-caprolactone) [P(LLA-CL)] (75:25) copolymer nanofibrous scaffold was produced by electrospinning. The diameter of the generated fibers was around 500 nm with an aligned topography which mimics the circumferential orientation of cells and fibrils found in the medial layer of a native artery. A favorable interaction between this scaffold with human coronary artery smooth muscle cells (SMCs) was demonstrated via MTS assay, phase contrast light microscopy, scanning electron microscopy, immunohistology assay and laser scanning confocal microscopy separately. Tissue culture polystyrene and plane solvent-cast P(LLA-CL) film were used as controls. The results showed that, the SMCs attached and migrated along the axis of the aligned nanofibers and expressed a spindle-like contractile phenotype; the distribution and organization of smooth muscle cytoskeleton proteins inside SMCs were parallel to the direction of the nanofibers; the adhesion and proliferation rate of SMCs on the aligned nanofibrous scaffold was significantly improved than on the plane polymer films. The above results strongly suggest that this synthetic aligned matrix combines with the advantages of synthetic biodegradable polymers, nanometer-scale dimension mimicking the natural ECM and a defined architecture replicating the in vivo-like vascular structure, may represent an ideal tissue engineering scaffold, especially for blood vessel engineering.

Structure and properties of electrospun PLLA single nanofibres

An electrospinning method was used to spin semi-crystalline poly(L-lactide) (PLLA) nanofibres. Processing parameter effects on the internal molecular structure of electrospun PLLA fibres were investigated by x-ray diffraction (XRD) and differential scanning calorimetry (DSC). Take-up velocity was found as a dominant parameter to induce a highly ordered molecular structure in the electrospun PLLA fibres compared to solution conductivity and polymer concentration, although these two parameters played an important role in controlling the fibre diameter. A collecting method of a single nanofibre by an electrospinning process was developed for the tensile tests to investigate structure-property relationships of the polymer nanofibres. The tensile test results indicated that higher take-up velocity caused higher tensile modulus and strength due to the ordered structure developed through the process.

Porous tubular structures with controlled fibre orientation using a modified electrospinning method

Electrospinning offers an avenue to produce small diameter tubes made out of nanofibres. However, to date, most tubes from electrospun fibres have been either random fibres or from sheets that were rolled into tubes. Although there have been suggestions of getting tubes made of circumferentially aligned fibres, this is the first time that a method used to create a tube made of diagonally aligned electrospun fibres has been described. This tube was formed by depositing fibres on a rotating tube during electrospinning to give a resultant tube with uniform thickness and superior all round mechanical strength without any line of weakness. A knife-edged auxiliary electrode was given a charge that was opposite to that of the charge given to the needle to create an electrostatic field that encouraged fibre alignment on a rotating tube collector. A tubular structure made of nanofibres aligned in a diagonal direction was produced through electrospinning.

Recent Advances In Tissue Engineering Applications Of Electrospun Nanofibers

that information on circul ating low molecular weight peptides can be correlated to certain disease states. Exploitation of the uni fo m1, small pores and surface functi onali za tion propertie enabled by porou silicon particles to extract and enabl e analys is of these peptides as suggested by Liotta et al (to diagnose the early stages of disease by analys i of the low molecular weight proteome using porous silicon particulates) is, in our opinion, feas ible and potentially quite powerful. Recent research on the penetration, loading, and adsorption of proteins into porous silicon, the use of porous silicon as a size-exclusion matrix for resolving protein sizes, and exceptional capacity to tune the pore size indi cate the potential for clinical use of porous silicon in proteomics. . . Furthermore, novel, contro llably dual-s ided, symmetric hydrophobi c and hydrophilic particul ates of porous _s ilicon have been conceived and are being fabri cated (see Figure 3 for an SEM image of the porous silicon surface) . They are prepared from a polysilicon precursor and are precisely size monodisperse on the sca le of one micron (d iameter and thickness). These particulates may enable unidirectional fl ow of transported drugs, proteins/peptides, nucleic ac ids, etc. They may also fac ilitate controllably different intraparti cle surface chemistries, and therefore potenti ally di fferent types of antibodie , proteins, etc., present on the same particle.