Fig. 6: Real-time tracking of individual cell contractility through changes in the refractive index with both internalised WGM microbeads and extracellular microbeads in contact with the cell membrane for nonphagocytic adult cardiomyocytes.
From: Review of biosensing with whispering-gallery mode lasers
a Continuous single-cell monitoring with an intracellular microbead over 10 min (top) at 2 nJ/pulse, and magnification of the 20 s window indicated by the red rectangle (bottom). b 3D arrangement of myofibrils around microbeads in neonatal cardiomyocytes (CMs). Cell nucleus (magenta) and microlaser (green). c WGM spectrum of a microlaser showing multimode lasing (left). Illustration of the redshift in the lasing wavelength upon CM contraction (right). d Microlaser attached to the atrium of a zebrafish heart (3 days post-fertilisation); scale bar 200 µm. e Average refractive index change (Δηext) between the resting phase (diastole) and peak contraction (systole) for 12 individual cells. f Extracellular microlaser (white arrow) on top of an adult CM. Scale bar 30 µm. g ηext trace of a spontaneously beating neonatal CM during administration of 500 nM nifedipine (black arrow). Reproduced from ref. 5
