Abstract: Disclosed herein are methods and systems that use a photonic crystal (PC) for interference scattering microscopy. Incident light is directed onto a surface of the PC and couples into a photonic crystal guided resonance (PCGR) mode of the PC such that less than 1% of the incident light is transmitted through the PC as transmitted light. One or more particles adjacent to the surface of the PC scatter a portion of the light coupled into the PCGR mode as scattered light. An image comprising a pattern of constructive and destructive interference between the transmitted light and the scattered light is formed, and an image sensor may capture one or more image frames of the image Imaging processing of the one or more image frames can be used to identify at least one scattering center corresponding to at least one particle of the one or more particles.

Abstract: The current disclosure provides a simple single-step room temperature Activate Cleave and Count (ACC) assay coupled to Photonic Resonator Absorption Microscopy (PRAM) in an amplification-free approach. The assay, and associated system and method disclosed herein allow for detection of viral and bacterial pathogens as well disease such as cancer at the point of care.

Abstract: Assays using nanoparticle probes can be used to detect a target oligonucleotide with digital resolution by measuring the peak wavelengths and/or peak intensities of resonantly reflected light from locations on the surface of a photonic crystal (PC). The PC is functionalized with a capture oligonucleotide that binds to a nanoparticle probe that has bound to the target analyte. The binding of the nanoparticle probe to the PC shifts the peak wavelength and reduces the peak intensity of the resonantly reflected light at the binding location. An example nanoparticle probe includes a metallic nanoparticle conjugated to a probe oligonucleotide bound to a protector oligonucleotide. The probe oligonucleotide includes a first portion complementary to the target oligonucleotide and a second portion complementary to the capture oligonucleotide.