The number, size and distribution of nanoparticles in urines of healthy people and stone patients were investigated by transmission electron microscopy (TEM). The results showed that the number of nanoparticles in healthy urines are more than that in lithogenic urines. The size of most nanoparticles in healthy urines ranges from 100 to 350 nm. However, the size of nanoparticles in patient urines changes from 100 nm to 1000 nm and more. A dynamic model about the formation of urinary stones was established. From this model, the nanoparticles in normal urines are stable, yet those in patient urines would easily aggregate to larger-size crystals and finally urinary stones formed. The results in this paper provide a new thought for preventing formation and recurrence of urinary stones.

The formation of calcium oxalate kidney stones was related to injuries of renal epithelial membranes. The liquid condensed (LC) domains in Langmuir-Blodgett (LB) film of dipalmitoylphosphatidylcholine (DPPC) were used as a model system to induce crystal growth of urinary mineral calcium oxalate monohydrate (COM). The circular defective boundaries between the LC and liquid expanded (LE) phases of the DPPC monolayer could provide much more nucleating sites for crystallization of COM crystals. It induced ring-shaped or solid circular patterns of COM crystals on hydrophobic quartz substrates depending on the crystallization time.

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