In this study, parallel-aligned poly(propylene carbonate) (PPC) microfibers with a fiber diameter of 1.48 perpendicular to 0.42 mu m were prepared by electrospinning and modified by oxygen plasma treatment. Next, chitosan nanofibers with a fiber diameter size of 278 +/- 98 nm were introduced into the PPC fiber mats by freeze drying. Morphological analyses showed that the PPC scaffolds treated with 0.05 mg/ml chitosan solution provided the best micro and nanofiber structure with abundant chitosan nanofibers but without the formation of films. Surface chemical properties were analyzed by X-ray photoelectron spectroscopy (XPS). The initial water contact angle of the scaffolds decreased from 122.3 +/- 0.4 degrees for neat PPC scaffolds to 53.8 +/- 1.6 degrees for scaffolds with plasma treatment and chitosan nanofibers. The mechanical properties of the scaffolds were affected by plasma treatment with Young's modulus experiencing a reduction of 63%. Meanwhile, Young's modulus experienced a 26% improvement after the introduction of chitosan nanofibers. Fibroblast cells were cultured on the scaffolds to study the effects of both the plasma treatment and the introduction of chitosan nanofibers on cell adhesion, proliferation, and morphology. The scaffolds with PPC microfibers and chitosan nanofibers showed a superior cell response in terms of cell attachment, cell proliferation, and cell-scaffold interactions over the other scaffolds. (C) 2014 Elsevier Ltd. All rights reserved.