Interferometric scattering microscopy is a newly emerging alternative to fluorescence microscopy in biomedical research and diagnostic testing due to its ability to detect nano-objects such as individual proteins, extracellular vesicles, and virions individually through their intrinsic elastic light scattering. To improve the signal-to-noise ratio, we developed photonic resonator interferometric scattering microscopy (PRISM) in which a photonic crystal (PC) resonator is used as the sample substrate. The scattered light is amplified by the PC through resonant near-field enhancement, which then interferes with the <1% transmitted light to create intensity contrast. Importantly, the scattered photons assume the wavevectors defined by PC’s photonic band structure, resulting in the ability to utilize a non-immersion objective without significant loss at illumination density as low as 25 W/cm2. We demonstrate virus and protein detection, including highly selective capture and counting of intact pseudotype SARS-CoV-2 from saliva with sensitivity equivalent to conventional nucleic acid tests. The results showcase the promise of nanophotonic surfaces in the development of resonance-enhanced interferometric microscopies, and as a single step, room temperature, and rapid viral detection technology.
Newly demonstrated advanced biosensor imaging technologies utilize the unique electromagnetic capabilities of photonic metamaterials to enhance the interaction between light and biological matter. The resulting capabilities address gaps in existing technologies for biomolecular analysis that rely upon enzymatic and chemical amplification, costly instrumentation, and complex assay protocols. Through amplification of the excitation/extraction efficiency of light emitting tags, absorption efficiency of nanoparticle tags, and scattering efficiency of biological analytes, technology platforms have been demonstrated that are capable of ultrasensitive, digital-resolution, room temperature, isothermal, rapid, and highly quantitative biomolecular analysis.
Fourier transform-second-harmonic generation (FT-SHG) imaging is used to quantitatively assess the structural
organization of collagen fibers in tendonitis-induced horse tendons. Fiber orientation, isotropy, and the ratio of forward
to backward SHG signal (F/B ratio) are used to differentiate the fiber organization between the normal and diseased
horse tendons. Each second-harmonic generation (SHG) image is divided into several smaller regions of interest (ROI)
and the aforementioned quantitative metrics are calculated across the whole grid. ROIs are further labeled as dark (no or
minimal presence of fibers), isotropic (random fiber organization), or anisotropic (regular fiber organization) regions.
Results show that the normal tendon possesses minimal isotropic regions and small standard deviations in the histograms
of orientation and F/B ratio, indicating an intact and highly regular fiber organization. However, the tendonitis-induced
horse tendons possess higher number of dark and isotropic regions, and larger standard deviations of the measured
parameters, suggesting significantly disoriented and disorganized collagen fibers. This type of quantification would be
highly beneficial in diagnosing and determining the stage of tendonitis in clinical settings. Not limited to tendonitis, the
technique could also be applied to other diseases that structurally affect collagen fibers. The advantage of FT-SHG over
the conventional polarization microscopy is also discussed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.