Electrospun Biomimetic Fibrous Scaffold from Shape Memory Polymer of PDLLA-co-TMC for Bone Tissue Engineering Min Bao, †,‡ Xiangxin Lou, †,‡ Qihui Zhou, †,‡ Wen Dong, †,‡ Huihua Yuan, †,‡ and Yanzhong Zhang* ,†,‡ † State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620, China ‡ College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China * S Supporting Information ABSTRACT: Multifunctional fibrous scaffolds, which com- bine the capabilities of biomimicry to the native tissue architecture and shape memory effect (SME), are highly promising for the realization of functional tissue-engineered products with minimally invasive surgical implantation possibility. In this study, fibrous scaffolds of biodegradable poly(D, L-lactide-co-trimethylene carbonate) (denoted as PDLLA-co-TMC, or PLMC) with shape memory properties were fabricated by electrospinning. Morphology, thermal and mechanical properties as well as SME of the resultant fibrous structure were characterized using different techniques. And rat calvarial osteoblasts were cultured on the fibrous PLMC scaffolds to assess their suitability for bone tissue engineering. It is found that by varying the monomer ratio of DLLA:TMC from 5:5 to 9:1, fineness of the resultant PLMC fibers was attenuated from ca. 1500 down to 680 nm. This also allowed for readily modulating the glass transition temperature Tg (i.e., the switching temperature for actuating shape recovery) of the fibrous PLMC to fall between 19.2 and 44.2 °C, a temperature range relevant for biomedical applications in the human body. The PLMC fibers exhibited excellent shape memory properties with shape recovery ratios of R r > 94% and shape fixity ratios of R f > 98%, and macroscopically demonstrated a fast shape recovery (∼10 s at 39 °C) in the pre-deformed configurations. Biological assay results corroborated that the fibrous PLMC scaffolds were cytocompatible by supporting osteoblast adhesion and proliferation, and functionally promoted biomineralization-relevant alkaline phosphatase expression and mineral deposition. We envision the wide applicability of using the SME-capable biomimetic scaffolds for achieving enhanced efficacy in repairing various bone defects (e.g., as implants for healing bone screw holes or as barrier membranes for guided bone regeneration). KEYWORDS: Shape memory polymer, electrospun fibrous scaffold, bone tissue engineering, biomineralization, osteoblasts, poly(D,L-lactide-co-trimethylene carbonate) 1. INTRODUCTION Shape memory polymers (SMPs), 1 a class of stimuli-responsive smart materials, are of tremendous potential for application in medical implants that need to be delivered through minimal invasive surgery. This is owing to their intrinsic shape recovery capability, 2,3 which enables a bulky device packed in a small- sized temporary shape to go through narrow passages for deployment in the body, and then return to its original shape upon being actuated by a stimulus or trigger (e.g., temperature, 4 moisture, 5 magnetism, 6 and ultrasound 7,8 ). In the past decade, while several SMP-based medical devices (or prototypes) have been explored for application in conventional biomedical engineering scenarios, such as cardiovascular stents, 4,9 self- tightening sutures, 10 dialysis needle adapters, 11 cold hibernated elastic memory foams for treating aneurysms 12 and thrombec- tomy device for clot removal, 13 shape memory properties have also gained interest in the field of tissue engineering and regenerative medicine (TERM) as an emerging strategy for creating intelligent tissue-engineered scaffolds/products to promote regeneration of functional tissues and organs in vivo. 14,15 In the context of SMPs for TERM, apart from their basic capability of permitting minimally invasive surgical implantation for structural support, a biodegradable SMP for a particular tissue scaffolding can also be designed to allow for exerting appropriate stresses between the scaffolding constructs and surrounding tissues (beneficial for mechanotransduction- mediated tissue remodeling), regulating cell behavior by changing substrate topography, 16 and eluting therapeutical agents in a precisely controllable manner. 17 Undoubtedly, such an SMP-enabled intelligent scaffold integrated with multiple functionalities is highly promising towards ultimately enhancing the tissue repair and regeneration efficacy in the physiological environment upon implantation. Electrospinning has been widely recognized as one of the most attractive enabling nanotechnologies to produce nano- scaled fibers that are suitable for a multitude of biomedical applications. 18 In particular, the use of electrospun nanofibers to construct biomimetic scaffolds for engineering diversified Received: November 13, 2013 Accepted: January 29, 2014 Published: January 29, 2014 Research Article www.acsami.org © 2014 American Chemical Society 2611 dx.doi.org/10.1021/am405101k | ACS Appl. Mater. Interfaces 2014, 6, 2611-2621