Nanomembrane-Based, Thermal-Transport Biosensor for Living Cells

Abstract
Knowledge of materials' thermal-transport properties, conductivity and diffusivity, is crucial for several applications within areas of biology, material science and engineering. Specifically, a microsized, flexible, biologically integrated thermal transport sensor is beneficial to a plethora of applications, ranging across plants physiological ecology and thermal imaging and treatment of cancerous cells, to thermal dissipation in flexible semiconductors and thermoelectrics. Living cells pose extra challenges, due to their small volumes and irregular curvilinear shapes. Here a novel approach of simultaneously measuring thermal conductivity and diffusivity of different materials and its applicability to single cells is demonstrated. This technique is based on increasing phonon-boundary-scattering rate in nanomembranes, having extremely low flexural rigidities, to induce a considerable spectral dependence of the bandgap-emission over excitation-laser intensity. It is demonstrated that once in contact with organic or inorganic materials, the nanomembranes' emission spectrally shift based on the material's thermal diffusivity and conductivity. This NM-based technique is further applied to differentiate between different types and subtypes of cancer cells, based on their thermal-transport properties. It is anticipated that this novel technique to enable an efficient single-cell thermal targeting, allow better modeling of cellular thermal distribution and enable novel diagnostic techniques based on variations of single-cell thermal-transport properties.

Citation
ElAfandy RT, AbuElela AF, Mishra P, Janjua B, Oubei HM, et al. (2016) Nanomembrane-Based, Thermal-Transport Biosensor for Living Cells. Small. Available: http://dx.doi.org/10.1002/smll.201603080.

Acknowledgements
R.T.E. conceived, designed, and performed the experiments and numerical simulations and wrote the manuscript. A.F.A. prepared the living cells for measurements and edited the manuscript. P.M. and B.J. performed epitaxial growth of GaN wafers and edited the manuscript. U.B. assisted in experimental setup and approved the manuscript. H.O., M.A.M., T.K.N., and J.S.M. provided useful discussions on the project, discussed the results, and edited the manuscript. B.S.O. supervised the project, discussed the progress and results, and edited the manuscript. The authors acknowledge funding support from King Abdulaziz City for Science and Technology (KACST) Technology Innovation Center (TIC) for Solid State Lighting, grant no. KACST TIC R2-FP- 008, King Abdullah University of Science and Technology (KAUST) baseline funding, grant no. BAS/1/1614-01- 01.

Publisher
Wiley

Journal
Small

DOI
10.1002/smll.201603080

Additional Links
http://onlinelibrary.wiley.com/doi/10.1002/smll.201603080/full

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