Ultrafast fluorescence imaging in vivo with conjugated polymer fluorophores in the second near-infrared window

Abstract

In vivo fluorescence imaging in the second near-infrared window (1.0-1.7 mm) can afford deep tissue penetration and high spatial resolution, owing to the reduced scattering of long-wavelength photons. Here we synthesize a series of low-bandgap donor/acceptor copolymers with tunable emission wavelengths of 1,050-1,350 nm in this window. Noncovalent functionalization with phospholipid-polyethylene glycol results in water-soluble and biocompatible polymeric nanoparticles, allowing for live cell molecular imaging at 41,000 nm with polymer fluorophores for the first time. Importantly, the high quantum yield of the polymer allows for in vivo, deep-tissue and ultrafast imaging of mouse arterial blood flow with an unprecedented frame rate of 425 frames per second. The high time-resolution results in spatially and time resolved imaging of the blood flow pattern in cardiogram waveform over a single cardiac cycle (B200 ms) of a mouse, which has not been observed with fluorescence imaging in this window before.

Shortwave infrared fluorescence imaging with the clinically approved near-infrared dye indocyanine green

“…Increasing the quantum yield, functionality, and biocompatibility of SWIR fluorophores is an active focus of emerging research studies (24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41).…”

Significant metal enhanced fluorescence of Ag2S quantum dots in the second near-infrared window

“…MEF is a well-recognized technology whereby the near-field interaction of fluorophores with metallic nanostructures will, under optimized conditions, lead to a substantial fluorescence enhancement. 8, 11 Previous work in our group explored MEF using Ag nanoparticle patterned surfaces manufactured from colloidal lithography. 9 The colloidal lithography technique allowed the fabrication of large area arrays of Ag triangular nanoparticles with controlled size, shape, and interparticle separation, and more importantly, with tunable optical features.…”

Recent Advances of Activatable Molecular Probes Based on Semiconducting Polymer Nanoparticles in Sensing and Imaging

“…This also stands when comparing SPNs with supramolecular nanoparticles, as they are generally assembled from small‐molecule dyes 26. Facile PEGylation (where PEG is polyethylene glycol) generally endows SPNs with good biodistribution, allowing them to act as whole‐body imaging agents to detect the target of interest in living animals after systemic administration 27. With all these advantages, SPNs have been widely used in cells imaging,[[qv: 27a,d]] activated cell sorting,28 sensing of chemical mediators,[[qv: 17b,c]] tumor imaging[[qv: 27e,29]] hemodynamic imaging,[[qv: 27g]] and optogenetics 30…”