Biological super-resolution imaging by using novel microsphere-embedded coverslips

Optical super-resolution imaging is a desirable technique in many fields, including medical and material sciences and nanophotonics. We demonstrated feasibility of optical microscopy, with resolution improvement by a factor of 2-3, by using microsphere-embedded coverslips composed of barium titanate glass microspheres (refractive index n ~1.9-2.1) fixed in a transparent layer of polydimethylsiloxane. Imaging was performed by a conventional microscope and a fluorescent microscope with the microsphere-embedded layer placed in a contact position with various biological specimens and semiconductor nanostructures. We investigated a biomedical application of microsphere-assisted imaging technique by immunostaining of kidney sections where cellular distribution of a motor protein Myo1c and a podocyte specific protein ZO-1 was analyzed. A significant visual enhancement in the distribution pattern of the proteins was noted in the stained glomeruli by using microsphere-assisted imaging technique. Our results suggest that microsphere-assisted imaging technique is a promising candidate for applications in medical and cancer research, as well as in microfluidics and nanophotonics.