Diverse States and Properties of Polymer Nanoparticles and Gel Formed by Polyethyleneimine and Aldehydes and Analytical Applications

Abstract

Multicolor polymer nanoparticles (or dots) were prepared via the reaction between hyperbranched polyethyleneimine (PEI) and aldehydes, and when the concentration of aldehydes was lower, the final mixture displayed gelation behavior. This phenomenon can be applied to visual detection of aldehydes. Moreover, the colors of the polymer dots and gel are varied by using different kinds of aldehydes, which can be utilized for visual discrimination of aldehydes. For simplicity, we focus our attention on the interaction between PEI and formaldehyde. The nanoparticles show an average diameter of 42 nm, emit bright cyan fluorescence with high quantum yield, and exhibit high water dispersibility and excellent photostability. Due to the advantages, our polymer nanoparticles (PNPs) are utilized as a fluorescent probe for imaging in living SK-N-SH cells. Furthermore, valuable explorations have been carried out on the fundamental properties of PNPs, such as concentration-dependent fluorescence, pH-dependent fluorescence, and solvent effect.

High‐Shear‐Imparted Tunable Fluorescence in Polyethylenimines

“…Similarly,a dding salicylaldehyde impartsf luorescence( l ex = 370 nm, l em = 495 nm) [14] which arises from the formationo fSchiff base moieties. [3,5] Hydrothermal treatmento fh PEI with aldehydes at 95 8Cg enerates fluorescent polymer nanoparticles, [3] depending on the pH which can complicate the processing. The carbamate anion is another moiety responsible for fluorescence( l ex = 364 nm, l em = 470 nm), formed by reacting PEI with CO 2.…”

“…Chemical incorporation of amide functional groups triggered enhanced fluorescencei ntensity and auto-fluorescence over aw ide range, and the resultingn anoparticles showeds ignificantly reduced cytotoxicity compared to as-received polymers.Fluorescent nanoparticles derived from amino-containing dendritic polymers have been used for biological imaging and biosensors [1][2][3] where the fluorophores are usually extended conjugated chemical structures. In this work, PEI nanoparticles of circa 10 nm in diameter,d evoid of such structural features and with tunable fluorescence, were generatedi na microfluidic platform.…”

“…[5] Refluxing 25 kDa PEIi nn itric acid at 120 8Cf or 12 ha ffords photoluminescent nanoparticles (l ex = 360 nm, l em = 450 nm) bearing amide linkages (NHCO). [3,5] Hydrothermal treatmento fh PEI with aldehydes at 95 8Cg enerates fluorescent polymer nanoparticles, [3] depending on the pH which can complicate the processing. [13] Adding formaldehyde at 90 8Cr esultsi nf luorescent polymericn anoparticles (l ex = 365 nm, l em = 508 nm) or gels (l ex = 350 nm, l em = 476 nm).…”

“…Fluorescent nanoparticles derived from amino-containing dendritic polymers have been used for biological imaging and biosensors [1][2][3] where the fluorophores are usually extended conjugated chemical structures. [4] Even though simple oxidation, acidification or methylation can further enhancet he intrinsic fluorescence, [5] the mechanism of fluorescencef rom these dendritic polymers is not well understood.…”

“…[11] Another new absorption band at ca. [3] The QY for PEI 800 0.1 mL min À1 and hPEI 0.1 mL min À1 was 3.7 and 7.0 %, respectively based on quinines ulfate as as tandard, and 7.4 %f or PEI 800 0.2 mL min À1 based on fluoresceina s as tandard (Table S1). p * transitions for C=Nm oieties.…”