Preparation of PLCL copolymer films with Lotus-leaf-like structured

1. Preparation of PLCL copolymer films with Lotus-leaf-like structured surface for blood compatible biomaterials B A A B D C A B Seung Il Kim1, Soo Hyun Kim1,2,* 81° ± 2° 90° ± 1.2° 103° ± 1.5° 107° ± 2° D C C D 1 Division of Life and Health Science, Biomaterials Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea 2 KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea Abstract Lotus-leaf-like structured PLCL copolymer films' surfaces were casted by using the solvent-nonsolvent casting method. PLCL copolymers were synthesized by well-known copolymerization process, and were confirmed by 1H-NMR analysis. The molecular weight was measured by gel permeation chromatography (GPC). The films were casted with various nonsolvent ratios. Tetrahydrofuran (THF) was used as the solvent and alcohols were used as the nonsolvent. Surface hydrophobic characteristic was confirmed by the water contact angle. The water contact angle was increased by surface topology modification. Prepared film surfaces were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). Platelet adhesion tests on the modified film surfaces were evaluated by platelet-rich plasma (PRP). The cell adhesive behavior on the modified film surfaces was also evaluated. Prepared lotus-leaf-like structured film surfaces exhibited reduced platelet adhesion behavior. Lotus-leaf-like Effect & Hydrophobic surface Fabrication of Lotus-leaf-like structure Objective Solvent-nonsolvent method Surface topography & its effects We investigated the effect on the homogeneity of non-solvent concentration (non-solvent ml/solvent ml) using a polymer solution(0.3 mg PLCL/10 ml THF) in addition to alcohols as a nonsolvent. After 4.5 g of PLCL copolymer was dissolved slowly in 150 ml THF at room temperature, alcohol was added. After stirring the mixed solution for 10 min, 10 ml of the mixed solutions was then dropped onto the cleaned Teflon mold substrate. After drying for 24 h at room temperature in vacuum, a modified PLCL copolymer surface was obtained. a: Hydrophobic surface, b: Lotus leaf surface Results & Discussion • Poly(ε-caprolactone)-block-poly(L-lactic acid) film surfaces • Poly(L-lactic acid-co-ε-caprolactone) film surfaces A K D H SEM images of the prepared PCL-b-PLLA film surfaces: A: 0 % (V EtOH / V THF), D: 30 % (V EtOH / V THF), H: 70 % (V EtOH / V THF), K: 100 % (V EtOH / V THF). White scale bars, 60 μm; black scale bars, 3 μm. Contact angle of the poly(l-lactic acid-co-ε-caprolactone) Film surfaces: A: 10 ml THF, B: 2 ml EtOH/10 ml THF, C: 3 ml EtOH/10 ml THF, and D: 5 ml IPA/10 ml THF Control SEM images of the poly(l-lactic acid-co-ε-caprolactone) film surfaces: A: 10 ml THF, B: 2 ml EtOH/10 ml THF, C: 3 ml EtOH/10 ml THF, and D: 5 ml IPA/10 ml THF Water contact angles of water drops on the casted PCL-b-PLLA films. The water contact angle was increased from 90.9 ° ± 4.2 ° to 130.2 ° ± 3.6 ° by surface topography modification: A ~ K: 0 ~ 100 % (V EtOH / V THF) A Contact angles of water drops on the poly(l-lactic acid-co-ε-caprolactone) Film surfaces: A: 10 ml THF, B: 2 ml EtOH/10 ml THF, C: 3 ml EtOH/10 ml THF, and D: 5 ml IPA/10 ml THF. D Prepared PCL-b-PLLA films X-ray diffraction (XRD) spectra: A: 0 % (V EtOH / V THF), D: 30 % (V EtOH / V THF), H: 70 % (V EtOH / V THF), K: 100 % (V EtOH / V THF) X-ray diffraction (XRD) spectra of the poly(l-lactic acid-co-ε-caprolactone) films: A: 10 ml THF, B: 2 ml EtOH/10 ml THF, C: 3 ml EtOH/10 ml THF, and D: 5 ml IPA/10 ml THF. H Live human dermal fibroblasts number on PLCL films following the culture period (3 h, 24 h, 48 h). Control: poly(l-lactic acid- co-ε-caprolactone) film, A: 0 % (V EtOH / V THF), D: 30 % (V EtOH / V THF), H: 70 % (V EtOH / V THF), K: 100 % (V EtOH / V THF) K Platelet adhesion tests of the poly(l-lactic acid-co-ε-caprolactone) film surfaces: A: 10 ml THF, B: 2 ml EtOH/10 ml THF, C: 3 ml EtOH/10 ml THF, and D: 5 ml IPA/10 ml THF. In vitro blood compatibility tests on the PLCL film surfaces. Platelet-rich plasma test (Left side) and Whole blood test (Right side). Black scale bars, 30 μm. White scale bars, 20 μm AFM images of the modified poly(l-lactic acid-co-ε-caprolactone) film surface (2 ml EtOH/10 ml THF). Conclusion In our research, lotus-leaf-like unique micron-submicron structured surfaces were cast by the solvent-non solvent method. Lotus-leaf-like structured PLCL copolymer film surfaces showed reduced platelet-biomaterial interactions, and will be beneficial in the development of low-thrombogenic surfaces for blood contacting medical devices. These unique lotus-leaf-like structured surfaces also show cytocompatible characteristics based on the results from the human dermal fibroblast proliferation test