Discovery of an Exceptionally Strong Luminescence of Polyethyleneimine‐Superparamagnetic Iron Oxide Nanoparticles

Abstract

Polyethyleneimine (PEI) is rarely recognized as a luminescent polymer but is frequently used for the production of cationic nanoparticles and tagged with an organic fluorophore to be tracked optically. Herein, a strongly luminescent, branched PEI‐superparamagnetic iron oxide nanoparticle (bPEI‐SPION) without a traditional fluorophore is reported. A tremendous enhancement (1200 times) in the weak blue luminescence of bPEI is achieved only if it is adsorbed on a SPION during the synthesis of nanoparticles, which is improved further upon protonation, irreversibly. This is quite unexpected since SPIONs are strong absorbers in the visible region. All reaction parameters, different synthetic methods, as well as protonation are studied as independent factors to understand the origin of such enhancement. Detailed spectroscopic analysis and density functional theory calculations indicate that partial amine oxidation and Fe3+ reduction takes place during the synthesis, which significantly contributes to the luminescence enhancement. In addition, PEI‐SPION exhibits excitation wavelength dependent emission and maintains its magnetic properties.

Porous α-Fe2O3@C Nanowire Arrays as Flexible Supercapacitors Electrode Materials with Excellent Electrochemical Performances

“…However, α-Fe 2 O 3 has a lower conductivity, which makes the reported α-Fe 2 O 3 electrode material possess a lower capacitance. Therefore, some strategies have been taken to improve the capacitance of α-Fe 2 O 3 materials, including designing the microstructure of the materials to shorten the transmission path of ion electrons; coating the surface with conductive polymers or carbon materials to improve the conductivity of the materials; and oxygen vacancies being introduced or doped with other metal elements [ 25 , 26 , 27 , 28 , 29 ]. However, the specific capacitance obtained is still far below the theoretical capacitance.…”

Theranostic potential of self-luminescent branched polyethyleneimine-coated superparamagnetic iron oxide nanoparticles

“…The procedure detailed in our previous study was followed [ 35 ]. Briefly, an aqueous reaction mixture composed of 0.07 M of FeCl 2 ·4H 2 O (Merck, USA), 0.14 M of FeCl 3 ·6H 2 O (Merck, USA), and 0.6 mM of bPEI (Aldrich, USA) was treated with ammonium hydroxide (Sigma-Aldrich, USA) at 80 °C under argon atmosphere.…”

“…Recently, we did report an exceptionally strong blue luminesce of branched PEI- (25 kDa) coated SPION nanoparticles [ 35 ]. Such strong luminescence in the visible range is very interesting considering that the fluorophore, which is branched PEI (bPEI), is directly attached to SPION which has strong absorbance in the visible window of the electromagnetic spectrum.…”

“…The latter is essential for the highly popular gene therapy, especially in the treatment of cancer [ 39 – 40 ]. Besides, SPIONs are already in the clinic as magnetic resonance imaging (MRI) agents and SPION@bPEI nanoparticles have a strong T2 signal (the signal that reflects the length of time it takes for the MR signal to decay in the transverse plane) [ 35 ].…”

Size‐controlled Synthesis of Hematite α‐Fe2O3 Nanodisks Closed with (0001) Basal Facets and {11‐20} Side Facets and their Catalytic Performance for CO2 Hydrogenation

“…In consequence, extensive investigation on the catalytic performance of iron oxide for CO 2 hydrogenation has been carried out over the past decade. Iron oxide nanoparticles show superior properties in some fileds, such as superparamagnetism and biodegradability . It has been demonstrated that the active sites of the iron oxide catalysts for the CO 2 hydrogenation are a kind of complex mixture of iron phases, mainly iron carbides and iron oxides .…”