Probing the Interaction of Magnetic Iron Oxide Nanoparticles with Bovine Serum Albumin by Spectroscopic Techniques

The interaction of magnetic iron oxide nanoparticles (MNPs) with bovine serum albumin (BSA) was investigated by fluorescence (FL), ultraviolet visible (UV−vis) absorption, Raman, and circular dichroism (CD) spectroscopy. Results indicated that MNPs quench BSA FL mainly by a static quenching mechanism. The FL quenching constants KSV were obtained as 2.44 × 108, 2.41 × 108, and 2.40 × 108 L·mol−1 at 291, 298, and 313 K, respectively. The thermodynamic parameters of enthalpy change ΔHθ, entropy change ΔSθ, and free energy change ΔGθ were −0.90 kJ·mol−1, 157.38 J·mol−1·K−1, and −47.80 kJ·mol−1 (298 K), respectively. The association constant (KA) and the number of binding sites (n) were 7.64 × 107 L·mol−1 and 46.55 at higher concentration of MNPs, and 1.35 × 106 L·mol−1 and 284.74 at lower concentration of MNPs. The analysis results suggested that the interaction was spontaneous and the electrostatic interactions played key roles in the reaction process. In addition, the Raman and CD spectra proved secondary structure alteration of BSA in the presence of MNPs

A model for CLV signaling (Adapted from [46] and [47]).

<p>A model for CLV signaling (Adapted from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089241#pone.0089241-Bleckmann1" target="_blank">[46]</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089241#pone.0089241-Gagne1" target="_blank">[47]</a>).</p

Peptide modification reduces the cytotoxicity of QDs. Data are the means of three independent replicates ± Standard Error (SE).

<p>Peptide modification reduces the cytotoxicity of QDs. Data are the means of three independent replicates ± Standard Error (SE).</p

Time course of full wavelength scanning of TGA-capped CdTe QDs.

<p>Time course of full wavelength scanning of TGA-capped CdTe QDs.</p

Absorption and fluorescence spectra of thiol-capped CdTe QDs in aqueous solution.

<p>Absorption and fluorescence spectra of thiol-capped CdTe QDs in aqueous solution.</p

CLV3-QD localizes to the cell membrane of <i>Arabidopsis</i> root protoplasts.

<p>A. Bright field of control cells with QDs; B. fluorescent field of control cells incubated with QDs. After incubation, the probes were washed and no fluorescence was observed; C. Bright field of cells incubated with CLV3-QD probes; D. fluorescent field of C; after incubation, the probes were washed and a green fluorescent circle was observed at the membrane of the cells. Scale bar, 50 µm.</p

Schematic of stem cell niche organization and maintenance in the plant shoot apical meristem (SAM) and root apical meristem (RAM).

<p>This conserved pathway involves feedback regulation of transcription by CLE dodecapeptides. The organizing center (OC) in SAM stem cell niche and the quiescent center (QC) in RAM stem cell niche are indicated in red in the diagram (Adapted from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089241#pone.0089241-Murphy1" target="_blank">[3]</a>).</p

Zero-coupling procedure for conjunction of the CLAVATA3 (CLV3) dodecapeptide and CdTe QDs.

<p>Zero-coupling procedure for conjunction of the CLAVATA3 (CLV3) dodecapeptide and CdTe QDs.</p

Wavelength Dependence of Fluorescence Quenching of CdTe Quantum Dots by Gold Nanoclusters

Metal nanoclusters (NCs) are well-known for their distinct molecule-like luminescent behaviors. Currently, some research has been conducted concerning their quenching properties for various dyes, but little is known about the interaction between metal NCs and other fluorescent materials such as quantum dots (QDs). In this paper, we report efficient quenching of fluorescence emission of mercaptoacetic acid (TGA)-coated CdTe QDs having identical protective layers but differing core diameters (1.04, 1.61, and 2.11 nm) by the bovine serum albumin (BSA)-protected Au25 NCs (0.8 nm metal core diameter) that have negligible plasmon bands in PBS buffer solution at pH 7.4. With UV–vis absorption spectroscopy and steady-state and time-resolved fluorescence spectroscopy, we found that fluorescence emission of all QDs decreased significantly upon addition of Au NCs, in combination with no decrease in average fluorescence lifetime, which was attributed to static quenching of QDs by Au NCs. Interestingly, the 515 nm emitting QDs are at least 1 order of magnitude more efficiently quenched than the other two QDs in spite of the similar degree of spectral overlap of the emission spectrum with the excitation spectrum of Au NCs. This study not only has brought to light the quenching properties of metal NCs for QDs but also provided fundamental guidelines and new opportunities for further investigations into the interaction between metal NCs and other materials

Additional file 1 of The shape-dependent inhibitory effect of rhein/silver nanocomposites on porcine reproductive and respiratory syndrome virus

Additional file 1. Includes details of reagents, cells and viruses used in the experiment, equipment used for all characterizations (UV-Vis, FTIR, TEM, XRD, TGA) involved in this study, experimental procedures for MTT assay, indirect immunofluorescence assay, western blotting assay, real-time quantitative reverse transcription polymerase chain reaction, virus titration and ROS assay, TEM images and UV-Vis absorption spectra of L-Rhe/Ag and S-Rhe/Ag at differect pH, cytotoxicity of L-Rhe/Ag and S-Rhe/Ag on MARC-145 cells