Breaking of the Phosphodiester Bond: A Key Factor That Induces Hemolysis

In-depth understanding the toxicity of nanomaterials in red blood cells (RBCs) is of great interest, because of the importance of RBCs in transporting oxygen in blood circulation. Although the toxic effects of nanoparticles in RBCs have been revealed, the conclusions from the literature are conflicting, and in particular, the toxic mechanism is still at the infant stage. Herein, we investigated the size-dependent toxicity of well-known CdTe semiconductor quantum dots (QDs) and revealed the exact toxic mechanism at the molecular level by confocal microscopy and Fourier transform infrared (FT-IR) spectroscopy techniques. We found that smaller mercaptosuccinic acid-capped CdTe QDs (MSA-QDs) with the green-emitting color could cause hemagglutination whereas the middle-size yellow-emitting MSA-QDs induced the formation of stomatocytes and echinocytes and the bigger size red-emitting MSA-QDs induced heavy hemolysis and the formation of lots of ghost cells. The FT-IR data proved that all the MSA-QDs were likely to bond to the RBCs membranes and caused the structural changes of lipid and protein in RBCs. But only the red-emitting MSA-QDs caused the breakage of the phosphodiester bond, which might cause the heavy hemolysis. To some extent, this is the first example that reveals the hemolysis mechanism at the molecular level

Size-Dependent Stability of Water-Solubilized CdTe Quantum Dots and Their Uptake Mechanism by Live HeLa Cells

Water-solubilized quantum dots have led to a promising application in cellular labeling and biological imaging. The physicochemical properties of water-solubilized quantum dots, particularly in a physiological environment, are strongly dependent on their size. In this paper, we systematically studied the stability of mercaptosuccinic acid-coated CdTe quantum dots (MSA-QDs) of about 2.3 and 5.4 nm diameters in various buffers with different pH values and under laser irradiation by fluorescence spectroscopy. It was found that larger MSA-QDs showed better stability. Size-dependent uptake of MSA-QDs by living HeLa cells was further investigated by confocal microscopy. In phosphate buffer solution, the larger MSA-QDs entered the cells mainly by endocytosis, and part of the smaller ones entered the cells by passive penetration. In cell culture medium, their uptake pathways could be changed due to the changes of their surface properties. The cytotoxicity of smaller and larger MSA-QDs was significantly decreased due to the adsorption of some biological components in the cell culture medium on the nanoparticles surface

Additional file 1 of Retrospective analysis of urethral anastomosis with ancillary maneuvers and intraoperative biaxial defect measurements to achieve a tension free guidance system for redo PFUDD treatment

Supplementary Material

The posterior leaflet.

<p>The posterior leaflet is deemed a portion of the semi-elliptic cylinder shell which is cut along the minor axis of the xy plane.</p

The geometric model of the human mitral valve

<div><p>The mitral valve, which lies between the left atrium and the left ventricle, plays an important role in controlling the uniflux of blood from the left atrium to the left ventricle as one of the four human heart valves. A precise description of the shape of human mitral valve has vital significance in studying its physiological structure and periodic movement. Unsatisfyingly, there is almost no unified mathematical description of the same shape of human mitral valve in literature. In this paper, we present a geometric model for human mitral valve, as an elastic shell with a special shape. Parametric equations for the shape of human mitral valve are provided, including the anterior and the posterior parts, which can be thought as portions of two interfacing semi-elliptic cylindrical shells. The minor axis of one ellipse is equal to the major axis of the other. All the parameters are determined from the statistical data. Comparison of fitting results with existing examples validates the accuracy of our geometric model. Based on the fitting shape, one can further simulate the physiological function of the mitral valve using a suitable dynamic physical equation.</p></div

The anterior leaflet.

<p>The anterior leaflets is deemed as a portion of the semi-elliptic cylinder shell which is cut along the major axis of the xy plane.</p

Visualization results.

<p>(A) is the visualization result of the anterior leaflet, and (B) is the visualization result of the posterior leaflet.</p

The boundary curve of the anterior leaflet.

<p>The value range of the variable <i>y</i>₁ is [0, <i>π</i>], and the range of the variable <i>y</i>₂ is [0, sin <i>y</i>₁].</p

The boundary curve of the posterior leaflet.

<p>The value ranges of variables of P1 are and <i>y</i>₂ ∈ [0, sin 3(<i>y</i>₁ − <i>π</i>)). The value ranges of variables of P2 are and . The value ranges of variables of P3 are and .</p

Coupling results.

<p>(A) is the vertical view of the coupling results, and (B) is the front view of the coupling results.</p