Low Concentrations of Zinc Oxide Nanoparticles Cause Severe Cytotoxicity Through Increased Intracellular Reactive Oxygen Species

With wide application of Zinc oxide (ZnO) nanoparticles, their biological toxicity has received more and more attention in recent years. In this research, two ZnO dispersions with different particle sizes, small size Zinc oxide (S-ZnO) and big size Zinc oxide (B-ZnO), were prepared using polycarboxylic acid as dispersant. We found that the S-ZnO nanoparticles showed stronger toxicity on Human Pulmonary Alveolar Epithelial Cells (HPAEpiC) under same concentration. Only 9 ppm S-ZnO could decrease HPAEpiC viability to about 50%, which means that, a small amount of well-dispersed ZnO nanoparticles in industrial production process may cause serious damage to the human body through oral inhalation. Focusing on mechanism for cytotoxicity, ZnO nanoparticles promoted generation and accumulation of Reactive Oxygen Species (ROS) in mitochondria via inhibiting Superoxide Dismutase (SOD) enzyme activity and reducing Glutathione (GSH) content. ROS in turn opened the mitochondrial Ca2+ pathway and lowered the Mitochondrial Membrane Potentials (MMP), leading to cell death. To simulate the lung environment in vitro, mixed dipalmitoyl phosphatidylcholine (DPPC) and ZnO nanoparticles (1:1) were incubated for 72 hours and then cytotoxicity was evaluated on HPAEpiC. Results showed that the cell viability was significantly increased, which proved that the DPPC effectively inhibited the toxicity of ZnO nanoparticles.

Holding breath

The physical properties of surfactant were identified in the early 1950s from research on warfare chemicals by Pattle in Britain and by Radford and Clements in the US. The causal relationship between respiratory distress syndrome and surfactant deficiency was established in Boston by Avery and Mead in 1959. The Australian obstetrician Liggins induced lung maturity with glucocorticoids in 1972, but his discovery was not fully accepted for another 20 years. When the major surfactant compound was identified as dipalmitoyl-phosphatidylcholine, this substance was nebulized with little effect and it became clear that there were other components of natural surfactant required besides phospholipids. A century of basic research was rewarded when Fujiwara introduced bovine surfactant substitution in Japan in 1980 to treat and prevent respiratory distress syndrome in preterm infants. Surfactant substitution greatly alleviated respiratory distress syndrome and increased the preterm infant’s chance of survival. In addition, it has set high scientific standards for the introduction of new therapies for neonates and made the randomized multicentre trial the favoured tool for clinical innovations.

Fibril Growth Behavior of Amyloid β on Polymer-Based Planar Membranes: Implications for the Entanglement and Hydration of Polymers

The design of biosensors and artificial organs using biocompatible materials with a low affinity for amyloid β peptide (Aβ) would contribute to the inhibition of fibril growth causing Alzheimer’s disease. We systematically studied the amyloidogenicity of Aβ on various planar membranes. The planar membranes were prepared using biocompatible polymers, viz., poly(methyl methacrylate) (PMMA), polysulfone (PSf), poly(L-lactic acid) (PLLA), and polyvinylpyrrolidone (PVP). Phospholipids from biomembranes, viz., 1,2-dioleoyl-phosphatidylcholine (DOPC), 1,2-dipalmitoyl-phosphatidylcholine (DPPC), and polyethylene glycol-graft-phosphatidyl ethanolamine (PEG-PE) were used as controls. Phospholipid- and polymer-based membranes were prepared to determine the kinetics of Aβ fibril formation. Rates of Aβ nucleation on the PSf- and DPPC-based membranes were significantly higher than those on the other membranes. Aβ accumulation, calculated by the change in frequency of a quartz crystal microbalance (QCM), followed the order: PSf > PLLA > DOPC > PMMA, PVP, DPPC, and PEG-PE. Nucleation rates exhibited a positive correlation with the corresponding accumulation (except for the DPPC-based membrane) and a negative correlation with the molecular weight of the polymers. Strong hydration along the polymer backbone and polymer–Aβ entanglement might contribute to the accumulation of Aβ and subsequent fibrillation.

The Interaction of Chondroitin Sulfate with a Lipid Monolayer Observed by Using Nonlinear Vibrational Spectroscopy

<p>We present the first vibrational sum-frequency generation spectroscopic study of chondroitin sulfate (CS) interacting with dipalmitoyl phosphatidylcholine (DPPC) at the air-liquid interface. In the presence of Ca²⁺ and CS, the DPPC headgroups reoriented, while the tail orientations remained mostly unchanged. The results further suggest a chiral secondary structure for CS.</p>

The Interaction of Chondroitin Sulfate with a Lipid Monolayer Observed by Using Nonlinear Vibrational Spectroscopy

<p>We present the first vibrational sum-frequency generation spectroscopic study of chondroitin sulfate (CS) interacting with dipalmitoyl phosphatidylcholine (DPPC) at the air-liquid interface. In the presence of Ca²⁺ and CS, the DPPC headgroups reoriented, while the tail orientations remained mostly unchanged. The results further suggest a chiral secondary structure for CS.</p>

The interaction of chondroitin sulfate with a lipid monolayer observed by using nonlinear vibrational spectroscopy

The first vibrational sum-frequency generation (VSFG) spectra of chondroitin sulfate (CS) interacting with dipalmitoyl phosphatidylcholine (DPPC) at air-liquid interface are reported here, collected at a laser repetition rate of 100...

Preparation of DPPC liposomes using probe-tip sonication: investigating intrinsic factors affecting temperature phase transitions

Liposomes are an important tool and have gained much attention for their promise as an effective means of delivering small therapeutic compounds to targeted sites. In an effort to establish an effective method to produce liposomes from the lipid, dipalmitoyl-phosphatidylcholine or DPPC, we have found important aspects that must be taken into consideration. Here, we used probe-tip sonication to prepare liposomes on a batch scale. During this process we uncovered interesting steps in their preparation that altered the thermodynamic properties and phase transitions of the resulting liposome mixtures. Using differential scanning calorimetry to assess this we found that increasing the sonication time had the most dramatic effect on our sample, producing almost an entirely separate phase transition relative to the main phase transition. This result is consistent with reports from the current literature. We also highlight a smaller transition, which we attribute to traces of unincorporated lipid that seems to gradually disappear as the total lipid concentration decreases. Overall, sonication is an effective means of producing liposomes, but we cannot assert this method is optimal in producing them with precise physical properties. Here we highlight the physical effects at play during this process.