In 2021 University of Georgia's lecturer prof. Saeid Sahmani's articles "Effect of hexagonal structure nanoparticles on the morphological performance of the ceramic scaffold using analytical oscillation response" and "Fabrication and resonance simulation of 3D-printed biocomposite mesoporous implants with different periodic cellular topologies" were published respectively in Ceramics International and Bioprinting. We asked him some questions about those publications. Here are his responses.

1. What impact can this research have on human life?

Nowadays, nanotechnology has an influence on almost all sectors of our life such as new tools for molecular and cellular biology, new materials for pathogen detection, and protection of the environment. Trabecular bone and many growing organisms are samples of natural porous structures in our body. For this reason, one of the most interesting applications of nanotechnology is its use in manufacturing porous tissue engineering parts as biological scaffolds having significantly improved structural properties as well as biomedical characteristics. On the other hand, in biomedical applications, the design of scaffolds plays an important role in their biocompatibility, the specific surface is highly dependent on the selected topological geometry. Generally, a bony scaffold is designed to mimic the healthy structure of the body with similar material as well as biological properties. Consequently, topological analysis of the porous structure of a bony scaffold plays an important role to optimize its biocompatibility.  

      In our research program, we focused on the progress of biomedicine science to manufacture mesoporous bio-nano composite bony scaffolds for using to accelerate the recovery of injured bone tissues. 

2. How exactly is the research subject connected to these issues? 

In the present study, 3D printing technology is employed to fabricate mesoporous polylactic acid-hydroxyapatite (PLA-HA) bio-nano composite bony scaffolds made of various periodic cellular topologies including cubic, cylindrical and hexagonal porosity configurations. In addition, because mechanical vibrating of a bony scaffold causes to enhance its capability, the frequency-response and amplitude-response associated with resonance behavior of a beam-type bony implant made of the fabricated bio-nano composite scaffolds are predicted analytically. Therefore, it has tried to propose an optimum mechanical design of 3D-printed PLA-HA bio-nano composite bony scaffolds for use in repairing defected bone tissues with excellent cell adhesion and protein absorption.

      For this purpose, we produced PLA-HA bio-nano composites via a milling machine. The use of HA nanoparticles improved the biological characteristics of the manufactured scaffolds due to their high free surface area. Thereafter, the prepared bio-nano composite powder is inserted into an extruder 3D printing machine, and the gear pulls the powder towards the related cast. After passing through the extrusion cast, the associated filaments are achieved to fabricate bony scaffold samples having various periodic cellular topologies including cubic, cylindrical and hexagonal porosity configurations via the proposed G-code files for a 3D software to consider the required adjustments for the 3D-printer machine. Afterward, the mechanical properties of the fabricated PLA-HA bio-nano composite mesoporous scaffolds are extracted experimentally corresponding to cubic, cylindrical and hexagonal porosities. By using scanning electron microscopy (SEM), X-ray diffraction (XRD), the permeability characteristics of the fabricated bio-nano composite scaffolds are captured after soaking in the simulated body fluid (SBF). Finally, the multiple time-scale technique is utilized to predict analytically the mechanical resonance characteristics of a beam-type bony implant made of the fabricated mesoporous PLA-HA bio-nano composite subjected to both subharmonic and superharmonic mechanical excitations.         

3. How can students get involved in this field and why should they do so?

Actually, our research program is a multidiscipline one incorporating a wide range of expertise.  Accordingly, students in different fields of study including Mechanical Engineering, Biology, Materials Engineering, Chemistry Engineering, and Mathematics can be involved in this program. 

     The concept of this research program is the topic of the day in the world, so the obtained results from it can be published in prestigious international journals. We started this research work in 2019 and so far (in less than two years), we have succeeded to publish 17 ISI articles in the best international journals. So, if a student is studying in the related disciplines and is interested in doing research on a novel subject and publishing articles in prestigious international journals, I think this research program will be amazing for him/her.   

4. What were the main challenges ad skills involved in conducting this research?

As I said before, a wide range of specialties is involved in our research program. Therefore, Mechanical Engineering and Mathematics students who have enough ability in writing computational codes, or analytical solutions of structural behaviors can be involved in this research plan. Also, Biology, Materials Engineering, and Chemistry Engineering students who are interested in the fabrication of new composite materials, analyzing permeability characteristics, and are able to work with scanning electron microscopy and X-ray diffraction can cooperate with us.       

5. What made you interested in conducting research on this subject?

After performing several types of research and publishing more than 150 ISI journal articles in the fields of computation nonlinear mechanics of nano/micro-structures and advanced composite structures, I attempted to make a link between these fields of study with applied biomechanical engineering context. For this purpose, I found that the mechanical design of biological scaffolds having optimal material properties as well as excellent biomedical characteristics is one of the most interesting subjects in the last decade. Accordingly, I decided to start this research plan in 2019 via collaborations with some of my friends who have research experience in biology.       

6. Could you tell us about your collaborators?

Yes, of course. Prof. Mohammad Mohammadi Aghdam is a faculty member of the Mechanical Engineering Department at the Amirkabir University of Technology. His research interest and specialty along my research program is solid design using 3D printing machines. Dr. Saeed Saber-Samandari is a faculty member of the New Technologies Research Center at the Amirkabir University of Technology. Our collaborations are using new techniques in the fabrication of biocomposite materials and performing biological experiments to capture their permeability characteristics.   

7. What feedback has this particular research received so far?

One of our findings and published articles in this research plan was selected as the most interesting research work of the year in 2021 by Iran Nanotechnology Innovation Council. Also, we have received several proposals for joint research programs from universities in Germany, China, and Turkey.  

8. What additional support did this research receive? 

I need to thank the University of Georgia for its support. The UG officials did not spare any help to perform our research project as much efficiently as possible. We are trying to construct a well-equipped composite materials laboratory in the UG School of Science and Technology in order to carry out our future researches at our university.