title: Surface Acoustic Waves (SAW)-Based Biosensing for Quantification of Cell Growth in 2D and 3D Cultures.
abstract: Detection and quantification of cell viability and growth in two-dimensional (2D) and three-dimensional (3D) cell cultures commonly involve harvesting of cells and therefore requires a parallel set-up of several replicates for time-lapse or dose-response studies. Thus, developing a non-invasive and touch-free detection of cell growth in longitudinal studies of 3D tumor spheroid cultures or of stem cell regeneration remains a major unmet need. Since surface acoustic waves (SAWs) permit mass loading-based biosensing and have been touted due to their many advantages including low cost, small size and ease of assembly, we examined the potential of SAW-biosensing to detect and quantify cell growth. Herein, we demonstrate that a shear horizontal-surface acoustic waves (SH-SAW) device comprising two pairs of resonators consisting of interdigital transducers and reflecting fingers can be used to quantify mass loading by the cells in suspension as well as within a 3D cell culture platform. A 3D COMSOL model was built to simulate the mass loading response of increasing concentrations of cells in suspension in the polydimethylsiloxane (PDMS) well in order to predict the characteristics and optimize the design of the SH-SAW biosensor. The simulated relative frequency shift from the two oscillatory circuit systems (one of which functions as control) were found to be concordant to experimental data generated with RAW264.7 macrophage and A549 cancer cells. In addition, results showed that SAW measurements per se did not affect viability of cells. Further, SH-SAW biosensing was applied to A549 cells cultured on a 3D electrospun nanofiber scaffold that generate tumor spheroids (tumoroids) and the results showed the device's ability to detect changes in tumor spheroid growth over the course of eight days. Taken together, these results demonstrate the use of SH-SAW device for detection and quantification of cell growth changes over time in 2D suspension cultures and in 3D cell culture models, which may have potential applications in both longitudinal 3D cell cultures in cancer biology and in regenerative medicine.
authors.affiliation: Center for Research and Education in Nanobioengineering, University of South Florida, Tampa, FL 33612, USA. taowang@mail.usf.edu.|Microfluidics and Acoustics Laboratory, Department of Mechanical Engineering, College of Engineering, University of South Florida, Tampa, FL 33612, USA. taowang@mail.usf.edu.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.affiliation: Center for Research and Education in Nanobioengineering, University of South Florida, Tampa, FL 33612, USA. rgreen1@health.usf.edu.|Department of Molecular Medicine, University of South Florida, Tampa, FL 33612, USA. rgreen1@health.usf.edu.
authors.forename: Ryan
authors.initials: R
authors.lastname: Green
authors.affiliation: Center for Research and Education in Nanobioengineering, University of South Florida, Tampa, FL 33612, USA. rrnair@gmail.com.|Departments of Internal Medicine, University of South Florida, Tampa, FL 33612, USA. rrnair@gmail.com.|Transgenex Nanobiotech Inc, Tampa, FL 33612, USA. rrnair@gmail.com.
authors.forename: Rajesh Ramakrishnan
authors.initials: RR
authors.lastname: Nair
authors.affiliation: Center for Research and Education in Nanobioengineering, University of South Florida, Tampa, FL 33612, USA. mhowell1@health.usf.edu.|Department of Molecular Medicine, University of South Florida, Tampa, FL 33612, USA. mhowell1@health.usf.edu.
authors.forename: Mark
authors.initials: M
authors.lastname: Howell
authors.affiliation: Center for Research and Education in Nanobioengineering, University of South Florida, Tampa, FL 33612, USA. smohapa2@health.usf.edu.|Department of Molecular Medicine, University of South Florida, Tampa, FL 33612, USA. smohapa2@health.usf.edu.
authors.forename: Subhra
authors.initials: S
authors.lastname: Mohapatra
authors.affiliation: Center for Research and Education in Nanobioengineering, University of South Florida, Tampa, FL 33612, USA. guldiken@usf.edu.|Microfluidics and Acoustics Laboratory, Department of Mechanical Engineering, College of Engineering, University of South Florida, Tampa, FL 33612, USA. guldiken@usf.edu.
authors.forename: Rasim
authors.initials: R
authors.lastname: Guldiken
authors.affiliation: Center for Research and Education in Nanobioengineering, University of South Florida, Tampa, FL 33612, USA. smohapat@health.usf.edu.|Departments of Internal Medicine, University of South Florida, Tampa, FL 33612, USA. smohapat@health.usf.edu.
authors.forename: Shyam Sundar
authors.initials: SS
authors.lastname: Mohapatra
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D002452:Cell Count / Q000379:methods*; D018929:Cell Culture Techniques / Q000379:methods*; D049109:Cell Proliferation; D002470:Cell Survival; D051379:Mice; D000067996:RAW 264.7 Cells; D013016:Sound; D015034:Zinc Oxide
chemical_list: D015034:Zinc Oxide
keywords: 3D cell culture; Biosensor; cancer; shear horizontal—surface acoustic waves (SH-SAW); surface acoustic waves (SAW); zinc oxide (ZnO)