Functionalization of manganite nanoparticles and their interaction with biologically relevant small ligands: Picosecond time-resolved FRET studies

Abstract

We report molecular functionalization of the promising manganite nanoparticles La0.67Sr0.33MnO3 (LSMO) for their solubilization in aqueous environments. The functionalization of individual NPs with the biocompatible citrate ligand, as confirmed by Fourier transform infrared (FTIR) spectroscopy, reveals that citrates are covalently attached to the surface of the NPs. UV-VIS spectroscopic studies on the citrate functionalized NPs reveals an optical band in the visible region. Uniform size selectivity (2.6 nm) of the functionalization process is confirmed from high resolution transmission electron microscope (HRTEM). In the present study we have used the optical band of the functionalized NPs to monitor their interaction with other biologically important ligands. Förster resonance energy transfer (FRET) of a covalently attached probe 4-nitrophenylanthranilate (NPA) with the capped NPs confirm the attachment of the NPA ligands to the surface functional group (-OH) of the citrate ligand. The FRET of a DNA base mimic, 2-aminopurine (2AP), with the NPs confirms the surface adsorption of 2AP. Our study may find relevance in the study of the interaction of individual manganite NPs with drug/ligand molecules.

Study of interfacial charge transfer in nanosemiconductor–molecule composites

“…Cyclic voltammetric studies were carried out to probe the efficient binding of ZnO nanoparticles with NSPI. Figure (b) shows the cyclic voltammogram of NSPI and NSPI–ZnO composite, and the composite shows a shift in peak potentials along with a decrease in peak current that shows that the CSZO nanoparticles have efficient binding with NSPI, which supports the electronic spectral results. The Fourier transform infrared (FT‐IR) spectra of NSPI and NSPI–CSZO composite are displayed in Fig.…”

“…The energy transfer efficiency is related not only to the distance between the acceptor and donor ( r 0 ) but also to the critical energy transfer distance ( R 0 ; Forster's energy transfer theory). That is, E = R 6 0 /( R 6 0 + r 6 0 ), where R 0 is the critical distance when the transfer efficiency is 50% and R 6 0 = 8.8 × 10 −25 K 2 N −4 φJ , where K 2 is the spatial orientation factor of the dipole, N is the refractive index of the medium, φ is the fluorescence quantum yield of the donor and J is the overlap integral of the fluorescence emission spectrum of the donor and the absorption spectrum of the acceptor . The value of J can be calculated by using the equation, J = ∫ F ( λ ) ε ( λ ) λ 4 d λ / F ( λ )d λ , where F ( λ ) is the fluorescence intensity of the donor and ε ( λ ) is the molar absorptivity of the acceptor.…”

Improved crystallinity, spatial arrangement and monodispersity of submicron La0.7Ba0.3MnO3 powders: A citrate chelation approach

“…The procedure involves an attack over the Mn sites first, thereby loosening the oxygen atoms and then further entering the matrix to remove La/Sr atoms. Very recently, such results have also been observed by Giri et al [29]. Indeed, if the powders were exposed for more than 4h, the complete sample was chelated by citric acid, forming a clear complex solution.…”

Ligand‐Induced Evolution of Intrinsic Fluorescence and Catalytic Activity from Cobalt Ferrite Nanoparticles

“…Corresponding excitation spectra are shown in Figure 3b.T he observed absorption peaks at 285 and 320 nm, for fluorescence-modified T-CoFe 2 O 4 NPs, which give rise to fluorescencea tl em = 413 nm, may be attributed to the LMCTtransition involving the highest occupied energy level of tartrate ligandsa nd the lowest unoccupied energy levels of Co 2 + /3 + or Fe 3 + metal ionc enters on the NPs' surface. [13] Co [14] so, the involvement of Co 3 + in generation of fluorescence is very likely.T hree additional fluorescencep eaks having maximaa tl em = 460, 514, and 560 nm, against excitations at [16] We can explain the generation of the three excitation bands with maximaa tl ex = 370,4 30, and 525 nm in terms of spectroscopic term symbols, owing to transitions of 4 www.chemphyschem.org 460, and 520 nm, using three different pulsed diode laser excitation sourceso fl ex = 294, 377,a nd 471 nm wavelengths, respectively.A se vident from the figure, the significantly larger average excited-state lifetime( t av )o ft he fluorescence-modified T-CoFe 2 O 4 NPs observed for the 400 nm fluorescenceb and (5.27 ns) compared to that for 460 nm (1.03 ns) and 520 nm (0.97 ns) fluorescenceb ands strongly suggests am echanistic difference in the origin of the fluorescencep eak at l em = 413 nm from the rest of the peaks. Whereas, the strong resemblance between the lifetimev alues of fluorescenceb ands at 460 and5 20 nm reveals their mechanistic similarity.C orresponding weight percentages are mentioned in Table 1 À 1 arise, owing to the CÀOH stretching modes, [19] whereas peaks at 1411a nd 1621 cm À1 are attributed to symmetric and asymmetric stretching modes of the carboxylate groups (COO À )o ft artrate, respectively.…”