Resolution enhancement in deep-tissue nanoparticle imaging based on plasmonic saturated excitation microscopy

• Main Authors: Gitanjal Deka, Kentaro Nishida, Kentaro Mochizuki, Hou-Xian Ding, Katsumasa Fujita, Shi-Wei Chu
• Format: Article
• Language: English
• Published: AIP Publishing LLC 2018-03-01
• Series: APL Photonics
• Online Access: http://dx.doi.org/10.1063/1.5021455

Recently, many resolution enhancing techniques are demonstrated, but most of them are severely limited for deep tissue applications. For example, wide-field based localization techniques lack the ability of optical sectioning, and structured light based techniques are susceptible to beam distortion due to scattering/aberration. Saturated excitation (SAX) microscopy, which relies on temporal modulation that is less affected when penetrating into tissues, should be the best candidate for deep-tissue resolution enhancement. Nevertheless, although fluorescence saturation has been successfully adopted in SAX, it is limited by photobleaching, and its practical resolution enhancement is less than two-fold. Recently, we demonstrated plasmonic SAX which provides bleaching-free imaging with three-fold resolution enhancement. Here we show that the three-fold resolution enhancement is sustained throughout the whole working distance of an objective, i.e., 200 μm, which is the deepest super-resolution record to our knowledge, and is expected to extend into deeper tissues. In addition, SAX offers the advantage of background-free imaging by rejecting unwanted scattering background from biological tissues. This study provides an inspirational direction toward deep-tissue super-resolution imaging and has the potential in tumor monitoring and beyond.