Multiple-layer guided surface acoustic wave (SAW)-based pH sensing in longitudinal FiSS-tumoroid cultures

Tao Wang; Ryan Green; Rasim Guldiken; Subhra Mohapatra; Shyam Mohapatra

doi:10.1016/j.bios.2018.10.011

Multiple-layer guided surface acoustic wave (SAW)-based pH sensing in longitudinal FiSS-tumoroid cultures

Biosens Bioelectron. 2019 Jan 15:124-125:244-252. doi: 10.1016/j.bios.2018.10.011. Epub 2018 Oct 12.

Authors

Tao Wang¹, Ryan Green², Rasim Guldiken³, Subhra Mohapatra⁴, Shyam Mohapatra⁵

Affiliations

¹ Center for Research and Education in Nanobioengineering, University of South Florida, Tampa, FL 33612, USA; Microfluidics and Acoustics Laboratory, Department of Mechanical Engineering, College of Engineering, University of South Florida, Tampa, FL 33612, USA; Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA; James A Haley VA Hospital, Tampa, FL 33612, USA. Electronic address: taowang@mail.usf.edu.
² Center for Research and Education in Nanobioengineering, University of South Florida, Tampa, FL 33612, USA; Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA. Electronic address: rgreen1@health.usf.edu.
³ Center for Research and Education in Nanobioengineering, University of South Florida, Tampa, FL 33612, USA; Microfluidics and Acoustics Laboratory, Department of Mechanical Engineering, College of Engineering, University of South Florida, Tampa, FL 33612, USA. Electronic address: guldiken@usf.edu.
⁴ Center for Research and Education in Nanobioengineering, University of South Florida, Tampa, FL 33612, USA; Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA. Electronic address: smohapa2@health.usf.edu.
⁵ Center for Research and Education in Nanobioengineering, University of South Florida, Tampa, FL 33612, USA; Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA; James A Haley VA Hospital, Tampa, FL 33612, USA; College of Pharmacy Graduate Programs, University of South Florida, Tampa, FL 33612, USA. Electronic address: smohapat@health.usf.edu.

PMID: 30390467
DOI: 10.1016/j.bios.2018.10.011

Abstract

A constitutively increased intracellular pH that is higher than the extracellular pH is emerging as a hallmark of cancer and determining pH could play a significant role in the measurement of drug responsiveness of tumor cells. However, a non-invasive, touch-free and real-time pH sensing as a research tool is lacking and remains a major unmet need. The purpose of the current study is to investigate a microfluidic surface acoustic wave (SAW) sensor platform capable of monitoring pH in cell and tumoroid cultures. A novel multi-layer guided SAW sensor integrated into a microfluidic channel was investigated theoretically and experimentally in detail for pH bio-sensing. Sensitivity and capability of the layer guided Love wave device was modeled using the finite element simulation. The model was verified experimentally, and a study monitoring pH of cell growth media is presented. This novel pH sensor is based on a 13.91 MHz center frequency SAW device coated with ZnO (500 nm) and IrO₂ (30 nm) layers to increase the sensitivity. A change in mechanical and electrical properties of the conductive IrO₂ layer was observed resulting from electrical corrosion induced by pH solutions affecting the charge distribution, SAW phase velocity and attenuation. By measuring the frequency shift induced by the change in SAW phase velocity between the test group and control group, the pH value of cell culture media from H460 cancer cell culture plates from day 0 to day 5 can easily be determined. To improve the sensitivity and stability of the sensor, a finite element method was used to optimize the layer thicknesses. Taken together, the results of experiments show the potential application of this device to be integrated with microfluidic channels and used in determining pH changes in longitudinal tumor cell cultures.

Keywords: Cancer; Microfluidic; PH Sensor; Surface acoustic wave (SAW); Tumoroids.

MeSH terms

Biosensing Techniques*
Cell Line, Tumor*
Culture Media / chemistry*
Finite Element Analysis
Humans
Hydrogen-Ion Concentration*
Microfluidics
Sound

Substances

Culture Media

Abstract

MeSH terms

Substances

Grants and funding