Raman Spectroscopic Studies on the Mechanisms of Membrane Damage Induced by Quartz and the Protective Effect of Aluminum Citrate.
Cao-CJ; Liu-SJ; Lin-KC
NIOSH 1990 Nov:1181-1185
The molecular mechanisms of quartz (14808607) induced membrane damage were studied by Raman spectroscopy. The mechanisms for the protective effect of aluminum-citrate (31142560) were also examined. Liposomes prepared from dipalmitoyl-phosphatidylcholine (DPPC) were pretreated with aluminum-citrate or aluminum-chloride (7446700) or untreated. They were then treated with 0, 0.5, or 1.0 milligram quartz or titanium-dioxide (13463677) dust. Raman spectra were recorded. The extent of membrane damage was assessed by monitoring changes in the DPPC spectra. Quartz shifted the carbon/nitrogen stretching band located at 715 reciprocal centimeters (/cm) approximately 2 to 3/cm toward lower frequency and significantly decreased its intensity. The band width was significantly increased. The intensity ratios of bands in the 1000 to 1200/cm region, which represented carbon/carbon and phosphorus/oxygen skeletal stretching vibrations, were significantly decreased by quartz. Carbon/hydrogen stretching vibrations occurring in the 2800 to 2900/cm region were also decreased. These changes were largely eliminated by aluminum-citrate or aluminum-chloride pretreatment. Titanium-dioxide did not significantly affect any of the spectral bands. The authors conclude that quartz damages DPPC liposomes primarily by acting on the carbon/nitrogen bond in the choline group. This results in the liposomes being deformed to fit the globular surface of the quartz particles. The protective effect of aluminum-citrate or aluminum-chloride is due to a direct action on the surface of the quartz particles which prevents the interaction between the quartz surface and the liposome membrane. Titanium- dioxide exerts only a weak effect on liposome membranes.
In-vitro-studies; Silica-dusts; Mineral-dusts; Aluminum-compounds; Chemical-structure; Membrane-dysfunction; Phospholipids; Prophylaxis; Spectrographic-analysis; Surface-properties;
14808-60-7; 31142-56-0; 7446-70-0; 13463-67-7;
DHHS (NIOSH) Publication No. 90-108
Proceedings of the VIIth International Pneumoconioses Conference