Preparation of polylactic acid-polylipoic acid nanospheres as drug targeting carriers.

Polylactic acid-polylipoic acid nanospheres (PLA-PLIA-NS) were prepared, and their properties as drug targeting dosage forms were evaluated. A computer optimization technique was applied to obtain particles with nanometer order diameters and spherical shapes. Optimum preparative conditions involved the use of 2.4% hydroxypropyl cellulose (HPC), as a stabilizing agent, 24 min ultrasonication time, and 20% PLIA content. PLIA, containing a thiol group, was used for the conjugation of antibodies with the PLA-PLIA-NS surface. In this way, fairly spherical particles of PLA-PLIA-NS with a mean diameter of about 500 nm were obtained. The conjugation was investigated to determine targeting ability more precisely. Using rabbit antihuman IgG (Fab' fragment) antibodies, conjugation with PLA-PLIA-NS was accomplished by a disulphide binding reaction. The PLA-PLIA-NS-antibody conjugates were found to recognize IgG antigen bound to the surface of Sepharose beads.

Fluoride remineralization of demineralized bovine tooth enamel and hydroxyapatite pellets.

Both bovine enamel and hydroxyapatite pellets were remineralized in a fluoride-containing remineralization solution after prior demineralization for various lengths of time. In both the enamel and pellet systems, the degree of remineralization attainable was directly related to the extent of prior demineralization, although the demineralized material was never 100% recovered in remineralization. In some cases, fluoride levels up to several thousand parts per million were found at depths as great as 50 micrometers from the surface. The stoichiometry of the remineralized material and electron microprobe examination were consistent with the formation of fluoridated hydroxyapatite rather than calcium fluoride.