Super-Resolution Radial Fluctuations (SRRF) nanoscopy in the near infrared

Abstract

Super resolution microscopy methods have been designed to overcome the physical barrier of the diffraction limit and push the resolution to nanometric scales. A recently developed super resolution technique, super-resolution radial fluctuations (SRRF) [Nature communications, 7, 12471 (2016)10.1038/ncomms12471], has been shown to super resolve images taken with standard microscope setups without fluorophore localization. Herein, we implement SRRF on emitters in the near-infrared (nIR) range, single walled carbon nanotubes (SWCNTs), whose fluorescence emission overlaps with the biological transparency window. Our results open the path for super-resolving SWCNTs for biomedical imaging and sensing applications.

Super‐Resolution Near‐Infrared Fluorescence Microscopy of Single‐Walled Carbon Nanotubes Using Deep Learning

“…Nevertheless, there are some cases in which the two Gaussians differ, such as in Figure 5b, where a local maximum appears between the two main peaks only in the SRRF output. This difference is attributed to “edge” artifacts in the SRRF algorithm [ 68 ] that may cause two separate SWCNTs to appear connected when, in fact, they are merely adjacent. This artifact is further discussed in the following section.…”

“…In a previous study, [ 68 ] we demonstrated improved resolution of videos using the SRRF algorithm, and showed that it could capture the bending dynamics [ 64 ] of diffusing SWCNTs and their mean‐square displacement. However, as SRRF uses temporal correlation within the radiality stack to create the final SRRF image, [ 45,90 ] the temporal resolution was decreased since ten consecutive frames were used by the SRRF algorithm to produce a single super‐resolved frame in the video output.…”

“…SRRF Analysis: Initial preprocessing of the images included a single pixel radius median filter to despeckle the images, and a rolling ball algorithm (radius 50) to remove the background using ImageJ. [45,94] High-resolution images were then obtained using a SRRF algorithm [45,68,90] using a ring radius of 0.5, radiality magnification of 4, and 6 axes in the ring. SRRF temporal analysis was done using a temporal radiality average (TRA), and an intensity weighting was performed to enhance radiality peaks.…”

“…Recently, SRRF has been also usefully applied to nIR fluorescence images and videos of SWCNTs. [68] Super-resolution microscopy pushes the boundaries of resolving nanometric structures and dynamics, and can shed light on complex biological structures at the microscale, utilizing imaging probes [69] and single particle tracking. [70] These methods, which have been used to unfold dynamic information in many systems such as crystalline hosts, [71] catalytic conversions, [72] and heterogeneous biological architectures, [73][74][75] are achieved by resolving frame-by-frame video recordings of single-particle diffusion to reconstruct the particle trajectory.…”

Monitoring the Activity and Inhibition of Cholinesterase Enzymes using Single-Walled Carbon Nanotube Fluorescent Sensors

“…Single-walled carbon nanotubes (SWCNTs) benefit from unique optical and electronic properties, which render them favorable fluorescent probes for imaging, sensing, and biomedical applications, − owing to their fluorescence in the near-IR range where tissue, blood, and biological samples in general are mostly transparent. − Moreover, SWCNT sensors are stable at room temperature, provide spatiotemporal information, and do not photobleach upon use, unlike many other fluorescent sensors. − The mechanism of SWCNT-based sensors usually relies on tailored functionalization of the nanotube surface, which mediates the interaction with the analyte of interest, such that binding of the target molecule results in a modulation of the emitted fluorescence. − Fluorescent SWCNT sensors were applied for the biosensing of different analytes and enzymes. ,,,,− These range from monitoring progesterone and cortisol in vivo (mice), fibrinogen and insulin in blood and cell culture, , nitroaromatics and pathogens , in vivo (plants), volatiles in the gaseous phase, to enzymatic activity. − …”