Sensor-Instrumented Scaffold Integrated with Microporous Spongelike Ultrabuoy for Long-Term 3D Mapping of Cellular Behaviors and Functions

Significance 

The generation of physiologically relevant in-vitro models of biological barriers can play a vital role in understanding human diseases and in the development of more predictive methods for assessing toxicity and drug or nutrient absorption. Similarly, the ability to record cellular behaviors and functions with high spatial and temporal resolutions would enable fundamental comprehension of the underlaying bio-physics and cellular electrophysiology. In the past, this has been achieved through the application of various sensing platforms such as optical imagers, graphene-based sensors – among others. However, majority of these traditional approaches have limited spatial resolution owing to the fact their conceptual use was 2D based.

Recent publications have reported on the development of injectable/roll-able scaffold systems that enabled spatially resolved 3D mapping of cellular behaviors and functions in human-tissue mimicking environment. Unfortunately, shortfalls still remain for their long-term, high-fidelity recording due to the lack of effective means to electrically decouple all of the necessary electronic instrument settings from submerged conditions in a cell culture medium that in many cases demand additional packaging so as to prevent wetting and damaging.

Therefore, the real-time monitoring of cellular behaviors and functions with sensor-instrumented scaffolds can in many ways provide a profound impact on fundamental studies of the underlying biophysics and disease modeling. In this view, a group of researchers from the Weldon School of Biomedical Engineering and School of Mechanical Engineering at Purdue University: Dr. Hyungjun Kim, Mr. Min Ku Kim, Mr. Bongjoong Kim, and Professor Chi Hwan Lee in collaboration with Dr. Hanmin Jang and Professor Dong Rip Kim from the School of Mechanical Engineering at Hanyang University developed an ultra-buoyant 3D instrumented scaffold that could remain afloat on the surface of culture medium and thereby provide favorable environments for the entire electronic components in the air while the cells reside and grow underneath. Their work is currently published in the research journal, ACS Nano.

Technically, the research team developed a 3D-stackable electronic scaffold (e-scaffold) integrated with an engineered ultra-buoy that allowed the entire structure to remain afloat on the surface of medium thereby offering favorable environments for both biological cells and electronics. Briefly, their approach entailed the fabrication of the e-Scaffold System where polyimide material was used. Next, the microporous sponge-like ultra-buoy system using a silicone elastomer (PDMS) were used. Generally, the approach ended with the measurement of impedance and ECG signal for a long period of time (weeks).

The authors reported that the physical stacking of the e-scaffold system enabled the incorporation of large numbers of addressable sensors in a multidirectional arrangement, offering the 3D mapping capability. Altogether, their findings suggested an expanded set of potential options such as long-term stable monitoring of tissue functions during/after in vivo transplant to replace diseased or damaged tissues.

In summary, the study demonstrated that the developed e-scaffold integrated system could allow for long-term, high-fidelity monitoring of cellular behaviors and functions in favorable environments for both biological cells and electronics. In an interview with Advances in Engineering, Professor Chi Hwan Lee emphasized that the presented setting could facilitate high-fidelity recording of electrical cell−substrate impedance and electrophysiological signals for a long period of time (weeks). Further, comprehensive in vitro studies revealed the utility of the presented platform as an effective tool for drug screening and tissue development.

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Sensor-Instrumented Scaffold Integrated with Microporous Spongelike Ultrabuoy for Long-Term 3D Mapping of Cellular Behaviors and Functions - Advances in Engineering Sensor-Instrumented Scaffold Integrated with Microporous Spongelike Ultrabuoy for Long-Term 3D Mapping of Cellular Behaviors and Functions - Advances in Engineering

About the author

Dr. Chi Hwan Lee is an Assistant Professor at Purdue University, with joint appointments in the Departments of Biomedical Engineering & Mechanical Engineering. His main research focus lies on developing flexible and stretchable materials and devices for wearable healthcare applications. He obtained a Ph.D. (2013) & M.S. (2009) degrees in Mechanical Engineering from Stanford University, and received a B.S. degree (2007) in Mechanical Engineering from Illinois Institute of Technology.

He is the recipient of Top Innovation Award (2013) from the Technology Connect World National Innovation Summit, Graduate Silver Award from Materials Research Society (2013), Purdue Faculty Award of Research Excellence (2017), Purdue Faculty Summer Grant Award (2017), Hanwha Advanced Materials Non-tenured Faculty Award (2018), and Ralph W. and Grace M. Showalter Research Trust Award (2018), Seed for Success Award (2018), Recognized for the Outstanding Purdue Engineering Teacher (2018), NIH Trailblazer Award for New and Early Stage Investigators (2019), KSEA Young Investigator Award (2019).

About the author

Dr. Kim received his Ph.D. in Mechanical Engineering from Stanford University, the United States, in 2012. Dr. Kim has published more 65 technical papers in the area of Mechanical Engineering. His research team has focused on design and fabrication of functional surfaces with three-dimensional nano/micro-scale structures and functional materials for enhanced interaction and interfacial phenomena. Dr. Kim joined School of Mechanical Engineering, Hanyang University, South Korea, as an assistant professor in 2012.

He is now an associate professor at Hanyang University in South Korea, and serves as a director of the center for 4th Industrial Revolution Pioneering University at Hanyang University. Dr. Kim is the recipient of Presidential Award for Honor Students in South Korea (2005), Graduate Student Award of Materials Research Society in the United States (2011), Excellence in Industry-Academic Cooperation Research by LG Electronics in South Korea (2015), and Hanyang University New Faculty Award of Excellence (2016 and 2017).

About the author

Hanmin Jang was born from South Korea in 1987. He received the bachelor and Ph.D. degrees from the Mechanical Engineering Department in Hanyang University, Seoul, South Korea in 2013 and 2019 respectively. He is currently with the Mechanical Engineering Department of Hanyang University as a Post-Doc. position. His main areas of research interest are the fabrication of 3D nanoscale and microscale structures integrated on functional polymeric materials and their surface adhesion controlling. His research interests cover the development of fabrication methods of 3D structures and transferring or integrating them onto the flexible and stretchable polymer substrates to improve the water/oil repellency, anti-icing and light modulation.

He had researched with Professor Lee’s group at Biomedical Engineering Department in Purdue University as a visiting scholar from 2016 to 2017 for the National Research Foundation of Korea (NRF) and Air Force Office of Scientific Research (AFOSR) joint research program. He has published 7 scientific papers and over 15 patents by participating in over 10 research projects.

About the author

Hyungjun graduated my PhD in the School of Life Science at Gwangju Institute of Science and Technology (GIST) and have postdoc training in the Department of Biological Sciences at Korea Advanced Institute of Sciences and Technology (KAIST). And I joined at Biomedical Engineering at Purdue University in early spring 2016. Hyungjun has been working flexible or bioresorbable silicon nanoneedle patch for delivering various biomolecules and sensor instrumented 3D cell culture scaffold for measuring various cellular behaviors and functions. 

About the author

Min Ku Kim received his B.S. degree in electrical engineering from the University of Illinois at Urbana-Champaign in 2013, and a M.S. degree in mechanical engineering from Purdue University, West Lafayette, Indiana, USA in 2018. He is currently pursuing his Ph.D. degree at the Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA. His current research interests include stretchable and flexible format of electronics for biomonitoring applications in wide range of scales from cellular level to human wearable healthcare systems.

Reference

Hyungjun Kim, Min Ku Kim, Hanmin Jang, Bongjoong Kim, Dong Rip Kim, Chi Hwan Lee. Sensor-Instrumented Scaffold Integrated with Microporous Sponge like Ultrabuoy for Long Term 3D Mapping of Cellular Behaviors and Functions. ACS Nano 2019, volume 13, page 7898−7904.

Go To ACS Nano

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