Science & Technology (Commonwealth Union) – The lotus leaf is a trailblazer in the realm of self-cleaning, water-resistant design. Water droplets almost levitate on its surface, which has a distinctive texture that captures air in its minuscule ridges and crevices.
Bioengineers from Rice University have capitalized on the lotus effect to create a system for cultivating clusters of cancer cells, shedding light on the difficult-to-study characteristics of tumors. The novel zinc oxide-based culturing surface emulates the structure of the lotus leaf, offering a highly adjustable platform for the high-throughput production of three-dimensional, nanoscale tumor models.
The superhydrophobic array device (SHArD), developed by the Rice University, bioengineer Michael King and colleagues, can be employed to create customizable, compact, and physiologically pertinent models for examining cancer progression, including metastasis – the stage when cancerous cells spread through the bloodstream from the primary tumor site to other body parts.
King, who is the corresponding author on a study published in ACS Nano that outlines the new culturing platform indicated that the investigation of metastasis, which is responsible for the majority of cancer fatalities, presents a particular obstacle due in part to the challenge of developing precise, high-throughput models. He stated that they are hopeful that this tool will provide new insights into this problematic stage of the disease and help us discover methods to halt or prevent its occurrence.
Currently, scientists and medical professionals depend on blood samples containing circulating tumor cells – a crucial indicator of metastasis – to comprehend the attributes of primary tumors and the factors that trigger cancer to spread. This sampling method, commonly known as “liquid biopsy,” often fails to yield sufficient quantities for comprehensive, large-scale investigations of metastatic processes.
“‘Safety in numbers’ unfortunately also applies to cancer cells circulating in the bloodstream,” says Alexandria Carter, who is a researcher in the King lab who is a co-author for the study. “Cancer cells traveling alone are more likely to succumb to shear stress destruction or immune cell attacks. However, when they travel in groups, the likelihood that they successfully reach and settle in other parts of the body increases.
“Those few lone cancer cells in a single blood draw are already rare, so isolating enough clusters for a detailed study is especially challenging. This is why SHArD is an exciting new tool for understanding primary and metastatic cancer.”
The King lab has on prior occasions achieved success in developing layers of nanorods made from halloysite, a naturally occurring material that encourages the attachment of circulating tumor cells while simultaneously deterring blood cells.
King, a Cancer Prevention and Research Institute of Texas Scholar who recently became the E.D. Butcher Chair of Bioengineering at Rice and serves as a special adviser to the provost on life science collaborations with the Texas Medical Center pointed out that when Kalana Jayawardana joined our lab as a new postdoctoral fellow in 2018, he began experimenting with growing zinc oxide nanorod surfaces. He further indicated that at the start they did not have a specific application in mind, but they were optimistic that the new material might possess unique properties valuable to cancer biology.
The project was later advanced by Maria Lopez-Cavestany, a doctoral student in the King lab. Under her direction, the research took an exciting turn, and she is now the lead author of the study as a newly minted Ph.D. graduate.
After successfully growing a stable “carpet” of zinc oxide nanotubes, the researchers applied a Teflon-like coating on top, effectively mimicking the structure of a lotus leaf. This involved combining nanoscale roughness with a hydrophobic layer, resulting in genuine superhydrophobicity—a term derived from Greek meaning “extreme fear of water.” To develop SHArD, the team incorporated a microwell grid with precisely sized compartments and then evaluated the system’s performance through testing.
