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Amphiphilic Perylene Bisimide–Polymer Conjugates by Cysteine-Based Orthogonal Strategy: Vesicular Aggregation, DNA Binding, and Cell Imaging
journal contribution
posted on 2022-04-01, 18:38 authored by Mahuya Kar, Md. Anas, Palash Banerjee, Arpana Singh, Prosenjit Sen, Tarun K. MandalPerylene bisimides (PBIs) with high
quantum yields and high chemical
and photophysical stabilities are usually suffering from poor solubility
in various solvents, including water, which restricts their use in
biomedical and other applications. Thus, in this study, as-synthesized
hydrophilic poly(1-vinylimidazole) (PVim) is introduced at both the
imide positions of the hydrophobic PBI unit by using l-cysteine
(Cys) bearing two orthogonally reactive groups to produce a water-
and organic-soluble PBI-based polymer conjugate. To do so, first, l-cysteine is used for thiol-mediated radical polymerization
of 1-vinylimidazole (Vim). In the next step, the cysteine-end-capped
poly(1-vinylimidazole) (Cys–PVim) with free −NH2 is coupled with perylene-3,4,9,10-tetracarboxylic dianhydride
(PDA) by employing a one-step microwave-assisted reaction to produce
PBI–(Cys–PVim)2 conjugate. The solution optical
properties of this conjugate are thoroughly investigated to ascertain
the extent of aggregation among PBIs units in both aqueous and organic
media. The aqueous PBI–(Cys–PVim)2 solution
emits characteristic green fluorescence of PBI under UV irradiation
of 365 nm wavelength. Owing to the presence of a protonable imidazole
moiety, the PBI–(Cys–PVim)2 conjugate shows
pH-dependent optical properties. The amphiphilic PBI–(Cys–PVim)2 molecules undergo self-assembly into vesicular nanostructures
in water as confirmed from cryo- and high-resolution-transmission
electron microscopy. The conjugate binds with ctDNA and plasmid DNA
in water to form polyplexes. The fluorescent PBI–(Cys–PVim)2 conjugate with low cytotoxicity and high quantum yield is
efficiently used for the imaging of HeLa cells. The cellular uptake
of the conjugate is studied at different time intervals and at different
pHs using fluorescence microscopy.
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transmission electron microscopysolution optical propertiesprotonable imidazole moietymolecules undergo selfmediated radical polymerizationfree − nhdifferent time intervalsdependent optical propertiesbased orthogonal strategy365 nm wavelengthhigh quantum yieldshigh quantum yieldconjugate shows phbased polymer conjugatehydrophobic pbi unit2 subcys – pvimhigh chemicalconjugate bindsvim ).vesicular nanostructuresvesicular aggregationvarious solventsuv irradiationusually sufferingthoroughly investigatedtetracarboxylic dianhydridestep microwavesoluble pbipoor solubilityplasmid dnaphotophysical stabilitiesnext steplow cytotoxicityimide positionshela cellsform polyplexesdna bindingcellular uptakeassisted reaction