Chemiluminescence of Conjugated-Polymer Nanoparticles by Direct Oxidation with Hypochlorite

Abstract

Chemiluminescence (CL) is an advantageous detection tool for in vivo imaging because of the high signal-to-noise ratio of its optical-signal readout, which does not require an external excitation source. Conjugated polymers (CPs) are now used as an energy acceptor in CL nanoparticles to enhance the CL. Here, we demonstrate CL from the direct oxidation of CP backbones in conjugated-polymer nanoparticles (CPNs) by hypochlorite. Such CL CPNs completely avoid the involvement of small-molecule CL donors. The strategy greatly simplifies CL-probes preparation and increases the stability of CL nanoprobes by overcoming the leakage problem of CL donors in nanoparticles. Hypochlorite can oxidize the vinylene bond (CC) in polyfluorene-vinylene (PFV)/polyphenylenevinylene (PPV) via π 2 −π 2 cycloaddition to form a PFV-or PPVdioxetane intermediate that is unstable and can spontaneously degrade into PFV-or PPV-aldehyde and generate photons. The dioxetane-intermediate formation was confirmed by UV−vis-absorption, fluorescence, nuclear-magnetic-resonance ( 1 H NMR), and Fourier-transform infrared (FT-IR) spectroscopy. The CL quantum yield (QY) of the brightest CL probe, -9H-fluorene-2,7-vinylene)-co-(1-methoxy-4-(2-ethylhexyloxy)-2,5-phenylenevinylene)] (90:10 mol ratio, CPN-PFV-co-MEHPV), was 17.79 einsteins/mol (namely, photons per particle). CPN-PFV-co-MEHPV was size-stable, noncytotoxic, selective, and sensitive for hypochlorite detection. The linear range and the LOD of CPN-PFV-co-MEHPV for ClO − detection are 2−30 and 0.47 μM. Thus, CPN-PFV-co-MEHPV was successfully applied for in vivo imaging of endogenously produced ClO − in living animals. We expect that the represented strategy could be extended to construct other CL nanoprobes for bioimaging and disease diagnosis by simply optimizing and transforming CP backbones; such CL CPNs will have a profound impact on the field of bioimaging.

An aggregation-induced emission dye-powered afterglow luminogen for tumor imaging

“…It is reported that the vinyl bonds of SPs can be oxidized by several ROS (e.g., 1 O 2 , H 2 O 2 and ClO À ) for chemiluminescence or aerglow imaging, 23,[27][28][29]52,53 which is also evaluated in this study and the result is shown in Fig. S4b.…”

“…Compared with other reported SPs (such as MEHPPV and its analogues), poly[(9,9-di(2-ethylhexyl)-9H-uorene-2,7-vinylene)-co-(1-methoxy-4-(2-ethylhexyloxy)-2,5phenylenevinylene)] (PFPV) is considered better as an aerglow substrate since its highest occupied molecular orbital (HOMO) is close to the lowest unoccupied molecular orbital (LUMO) of dioxetane intermediates, and thus the intermolecular electron transfer between them can be facilitated, improving the quantum yield. 27,28 However, the light-induced 1 O 2 generation of PFPV is relatively low which results in unsatisfactory aerglow intensity and duration, and the short emission wavelength (<600 nm) hinders its in vivo imaging applications. 29,30 Therefore, increasing the amount of 1 O 2 generation and red-shiing of the emission are urgently needed for bioimaging.…”

Chemiluminescence and Bioluminescence Imaging for Biosensing and Therapy: In Vitro and In Vivo Perspectives

“…With the development of the optical equipment, CL has been well advanced from in vitro imaging to in vivo imaging. To resolve the problem of light transmittance and tissue self-absorption during CL imaging in vivo , novel and biocompatible CL probes have been fabricated, such as multifunctional polymer nanoparticles (NPs) 69 and near-infrared (NIR) fluorescent dyes 70-72. It should be noted that the NIR fluorescence generated from these fluorescent dyes is not direct CL emission but the non-radiative energy transfers from the CL substrate to fluorescent receptor which can emit at NIR region.…”

Recurring Real-Time Monitoring of Inflammations in Living Mice with a Chemiluminescent Probe for Hypochlorous Acid

“…Recently, chemiluminescence becomes an emerging platform for bio-imaging without any laser excitation and luciferase transfection. [22][23][24][25] Specifically, 1,2-dioxetane has been extensively used in activity-based sensing: a carefully designed masking group could be selectively deprotected by its analyte or enzymatic activity to release the energy stored in chemical scaffold in terms of light emission. [26][27][28][29][30] Chemiluminescent probes have demonstrated advantages of high sensitivity, low background, tunable kinetics, and operational simplicity.…”