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The effect of zinc oxide doping on mechanical and biological properties of 3D printed calcium sulfate based scaffolds

Aldemir Dikici B., Dikici S., Karaman O., Oflaz H.

Biocybernetics and Biomedical Engineering

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2017

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Vol. 37, no. 4

733--741

EN

Fabrication of defect-matching scaffolds is the most critical step in bone tissue engineering. Three-dimensional (3D) printing is a promising technique for custom design scaffold fabrication due to the high controllability and design independency. The objective of this study is to investigate the effect of zinc oxide (ZnO) doping on mechanical and biological characteristics of 3D printed (3DP) calcium sulfate hemihydrate (CSHH) scaffolds. Crystalline phases, wettability, compressive strength and Young's modulus, human bone marrow derived mesenchymal stem cells (hMSCs) attachment, proliferation and morphology were investigated. XRD results showed that CSHH powder transformed into gypsum after the printing process due to the water content of binder. Contact angle measurements indicated that ZnO doped CSHH scaffolds have hydrophilic character, which stimulates cell attachment. The mechanical and cell culture studies demonstrated that increasing the ZnO doping concentration both mechanical strength and cell proliferation on CSHH scaffolds were enhanced.

2

A biomechanical comparison between tissue stiffness meter and shore type 00 durometer using fresh human fetal membrane cadavers

Oflaz H.

Biocybernetics and Biomedical Engineering

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2016

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Vol. 36, no. 1

138--144

EN

A manual palpation is traditionally used on soft tissue stiffness evaluation in clinical practices. However, the palpation is a subjective technique, so quantitative tissue stiffness measurement would be a more reliable method on diagnosing disorders instead of a palpation in medicine. The purpose of this study was to emphasize a new medical device that was capable of measuring soft tissue stiffness. An in vitro investigation with a soft tissue stiffness meter (STSM) was presented and it is compared with a shore type 00 durometer in this study. Soft materials were needed for in vitro experiments to show feasibility of the STSM, so fetal membranes were decided to use on experiments. Five fetal membranes undergoing normal birth (NB) (35 samples, 105 measurements) and four fetal membranes undergoing pre-term birth (PRB) (20 samples, 60 measurements) were collected immediately after delivery. Samples were examined on custom designed tissue holder. Resu*lts of the STSM were in correlation with results of the durometer for NB and PRB (r2 = 0.995 and r2 = 0.996 respectively). Moreover, a tissue stiffness difference between NB and PRB was statistically significant by using STSM ( p ≤ 0.001), whereas it was not statistically significant by using durometer ( p = 0.360). In conclusion, newly produced device, STSM is more sensitive than durometer even for very small stiffness differences as between NB and PRB fetal membranes.

3

A new medical device to measure a stiffness of soft materials

Oflaz H., Baran O.

Acta of Bioengineering and Biomechanics

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2014

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Vol. 16, no. 1

125--131

EN

An objective in vivo measurement technique for assessing the material properties of soft tissue would be a valuabe tool in diagnosing dermatological pathologies. In order to make advancements in this field, a new hand-held device was designed to measure the stiffness of soft materials. The device measures the reaction forces experienced by the soft tissue under constant indentation deformations at the time of stiffness measurement. Agarose gel samples were prepared in a range of molarities to mimic the stiffness variabilities found in vivo. The stiffness of each gel was evaluated using two different measurement techniques. The first method utilized an industry standard durometer, designed to measure the hardness of materials in shore type 00 scales of soft plastics. The second measurement was taken using an original custom-built soft tissue stiffness meter, designed specifically for the present study. These two devices were compared and a strong correlation was found between them (r2 = 1.00, Spearman rank test). Additionally, it was observed that gels of different stiffness could be distinguished by both devices. In conclusion, the soft tissue stiffness can be accurately evaluated using the proposed device. The new device should be evaluated on human subjects in future studies, before it can be used to assess soft tissue disorders.