Fluorescence Imaging of Mammalian Cells with Cationic Conjugated Polyelectrolytes

Abstract

Fluorescence imaging using poly(phenylene ethynylene) (PPE) based conjugated polyelectrolytes (CPEs) has garnered considerable attention in the recent past due to their remarkable photophysical properties. In this report, we studied the fluorescence imaging properties of a set of six PPE‐based CPEs appended with side chains varying in structure and number of cationic charges. The photophysical and aggregation features of the CPEs depend on the overall charge density on the polymer in water. The cytotoxicity of the CPEs was evaluated against MCF‐7 mammalian cells, which revealed that polyelectrolytes with less cationic charge are less cytotoxic and vice versa. Confocal laser scanning microscopy (CLSM) studies showed that all the CPEs could efficiently penetrate into the MCF‐7 cells after 10 h of incubation. The transit of CPEs into the lysosomes was confirmed by comparison with the uptake of LysoTracker Red DND‐99 dye, which also revealed that the polyelectrolytes are highly photostable. We also demonstrated that the imidazolium‐functionalized CPEs could selectively stain bacteria over mammalian cells, suggesting the importance of CPEs for clinical applications.

Highly Effective Inactivation of SARS-CoV-2 by Conjugated Polymers and Oligomers

“…This lower concentration of either polymer demonstrated statistically insignificant differences in viral titer compared to the inhibition observed using 10 μg/mL ( Figure 5 ). Similar to the oligomer results and previously reported data, 22 , 31 , 37 we observed neither cytopathic effects of the polymers alone on Vero cells nor reduction in viral titer by the plaque assay when polymers were incubated with the virus in the dark (data not shown). We therefore conclude that the “inner filter” effect is not interfering with the antiviral activity of poly-4 and poly-5 in these conditions.…”

“…Importantly, consistent with previous findings, these oligomers demonstrated no cytopathic effects when added to Vero cell monolayers in the absence of virus (data not shown). 22 , 31 , 37 , 55 In addition, the effect of the compounds alone in the absence of light for viral inhibition was investigated. A significant cytopathic effect of the virus on the Vero cells was observed following incubation for 60 min in dark conditions in the presence of compounds.…”

“…Encouragingly, these materials exhibit relatively low toxicity against mammalian cells or the human skin. 29 − 31 Depending upon the selection of materials and properties, such as solubility and stability, it is possible to control the lifetime of these materials in coatings, with photodegradation as the main route of inactivation. 32 The most common byproducts of photodegradation, due to oxidative cleavage, are aldehydes and carboxylic acids that are unlikely to damage the environment.…”

Rapid and Effective Inactivation of SARS-CoV-2 by a Cationic Conjugated Oligomer with Visible Light: Studies of Antiviral Activity in Solutions and on Supports

“…Preliminary results of the testing indicate that 1 is non-toxic in tests of eye irritation on rabbits, oral toxicity in rats, and nonirritating in dermal testing in rabbits. These tests are consistent with what we have found in tests conducted in our laboratories with several other phenylene ethynylene polymers and oligomers 25,26,27.…”

Rapid and Effective Inactivation of SARS-CoV-2 with a Cationic Conjugated Oligomer with Visible Light: Studies of Antiviral Activity in Solutions and on Supports

“…These tests are consistent with what we have found in tests conducted in our laboratories with several other phenylene ethynylene polymers and oligomers. 22 − 24 …”