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Zhao M.-D.,Fudan University | Bjorninen M.,Institute of Biosciences and Medical Technology BioMediTech | Bjorninen M.,University of Wollongong | Cao L.,Fudan University | And 14 more authors.
Biomedical Materials (Bristol) | Year: 2015

Polypyrrole (PPy) has gained interest as an implant material due to its multifunctional properties and its high compatibility with several cell and tissue types. For the first time, the biocompatibility and osteointegration of PPy coating, incorporated with chondroitin sulfate (CS), were studied in vivo by implanting PPy-coated bioabsorbable bone fixation composite screws of poly-(lactide/glycolide) copolymer (PLGA) and β-tricalcium phosphate (TCP) into New Zealand white rabbits. Uncoated bioabsorbable polymer composite screws and commercially available stainless steel cortical screws were used as reference implants. The rabbits were euthanized 12 and 26 weeks after the implantation. The systemic effects were evaluated from food and water consumption, body weight, body temperature, clinical signs, blood samples, internal organ weights, and histological examination. Local effects were studied from bone tissue and surrounding soft tissue histology. New bone formation was evaluated by micro-computed tomography, tetracycline labeling and torsion tests. Torsion tests were performed in order to capture the peak value of the torsion force during the course of the screw's loosening. The coated screws induced significantly more bone formation than the uncoated screws. In addition, none of the implants induced any systemic or local toxicity. The results suggest that PPy is biocompatible with bone tissue and is a potential coating for enhancing osteointegration in orthopedic implants. © 2015 IOP Publishing Ltd.

Zhao F.,Tampere University of Technology | Zhao F.,Institute of Biosciences and Medical Technology BioMediTech | Kreutzer J.,Tampere University of Technology | Kreutzer J.,Institute of Biosciences and Medical Technology BioMediTech | And 2 more authors.
2014 IEEE International Conference on Mechatronics and Automation, IEEE ICMA 2014 | Year: 2014

Recent studies have shown that mechanical stimulation by means of mechanical stretching can enhance the cardiac differentiation and proliferation. Thus, several types of devices have been developed for mechanically stimulating the cardiomyocytes (CMs). However, some of the emerging devices need to be improved to satisfy the specific needs in applications. In this study, a computational model is developed for a novel cell stretching device by a finite element (FE) approach, and two significant parameters in terms of in-plane strain and out-of-plane displacement of the cell substrate are improved. This paper describes a method of geometric parametric variation to enhance the design and reports a reduction of the out-of-plane displacement from 315 μm to 4.8μm, while maintaining the maximum in-plain strain of more than 5%. © 2014 IEEE.

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