Single nanofibers of chitosan, collagen, and their blends were produced and the interactions between collagen and chitosan and the properties of the fibers obtained were evaluated [08Che1]. Collagen and chitosan were dissolved using HFIP or trifluoroacetic acid and electrospun at room temperature. A new electrospinning arrangement was done to collect single nanofibers for tensile testing. Single fibers with diameters of several micrometers were obtained but it was not possible to obtain single nanofibers. However, the electrospun matrix produced had fibers in the nanometer range. Tensile properties of the single electrospun fibers with various ratios of chitosan are given in Table 58.5 [08Che1]. As seen in the table, increasing the amount of chitosan increased the strength and modulus up to 50 %. Interest­ingly, the elongation of the fibers is considerably low except when the chitosan ratio was 20 % at which the elongation was as high as 46 %. The changes in the tensile properties of the membranes were attributed to the interchanges in the intermolec­ular interactions between chitosan and collagen.

To combine antimicrobial and cell adhesion properties, chitosan was blended with gelatin and electrospun into nanofibrous scaffolds for skin tissue engineering [10Dha]. Fibers with diameters between 120 and 220 nm were obtained using 50/50 ratio of chitosan and gelatin. Average tensile strength of the 50/50 blend scaffolds was 26 MPa, significantly higher than that of the matrices developed from the individual polymer. Blend scaffolds were suggested to have strength similar to that of skin.

Single fibers and membranes were formed from blends of collagen-chitosan by electrospinning and their mechanical properties were investigated [09Che]. Mechanical properties were found to be dependent on the diameter of the fibers and the ratio of collagen to chitosan in the fibers. Fibers with smaller

Table 58.5 Properties of electrospun single chitosan-collagen fibers with different chitosan contents [08Chel] Chitosan (%) 0 20 40 50 60 80 Diameter (pm) 7.8 ±5.0 7.4 ±1.2 6.8 ± 12.1 5.6 ±4.0 3.4 ±0.8 9.1 ±1.4 Strength (MPa) 23.7 ±5.8 21.7 ±19.3 62.8 ±14.1 61.8 ±26 47.0 ±19.1 10.5 ±8.0 Elongation (%) 2.6 ±1.4 46.0 ± 23 1.2 ±0.4 1.3 ±0.8 1.3 ±0.7 0.4 ±0.04 Modulus (MPa) 1,371 ±225 1,611 ±793 5,966 ±2,137 6,801 ±3,256 4,159 ±1,195 3,601 ±485

diameters had higher strength but low elongation. Single fibers from the chitosan- collagen blend had average diameters ranging from 434 to 691 nm and had strength between 20 and 60 MPa, elongation between 5 and 50 %, and modulus between 1 and 7 GPa depending on the chitosan content in the blend.