Liposome-stabilized Amorphous Calcium Carbonate (ACC)Derk Joester, Northwestern University, DMR 1106208

The use of amorphous minerals as precursors is a widespread strategy in biomineralization that is thought to play a major role in the biological ability to control polymorph and crystal shape, introduce smooth, curving surfaces, and impart outstanding mechanical properties. This level of control is still beyond our synthetic capabilities.

Unlike most in vitro syntheses performed in bulk solution, biological processing of amorphous minerals typically occurs in small phospholipid bilayer-delineated compartments. To understand the influence of confinement we use liposomes to model the biologically controlled intracellular precipitation of ACC. We find that liposome-encapsulated ACC nanoparticles are stable against aggregation and crystallization, and are ideally suited to investigate the influence of lipid chemistry, particle size, and soluble additives on ACC in situ.

C. Tester, R. Brock, C.-H. Wu, M. Krejci, S. Weigand and D. Joester , CrystEngComm 2011 C. Tester, C.-H. Wu, S. Weigand and D. Joester, Faraday Discussions 2012

Liposome-stabilized ACC nanoparticles are prepared by passive diffusion of ammonium carbonate into calcium loaded liposomes.

Cryo-TEM and Wide angle X-ray scattering of precipitation of CaCO3 in (i) 0.1 and (ii) 1 um liposomes; (ii) Bulk precipitation; calcite; vaterite.

Niles North high school junior Haley Sproull, investigated uptake of strontium into plant phytoliths as a model for phytoremediation of radio-active waste. She was selected a finalist at the Illinois Junior Academy of Science science fair. Haley presented her project at the 2012 Intel Internat. Science and Engineering Fair (ISEF) and won a 4th prize in her category.

Fei-Yin Luk, in a continuation of her undergraduate research project in our lab, combined liposomal encapsulation of Doxorubicin and co-precipitation with calcium carbonate. Sequestration in a non-toxic and biodegradable mineral phase may prolong circulation and promote targeted delivery to tumors.

Left: Fei-Yin Luk preparing liposomes. CryoTEM of liposome-encapsulated co-precipitates of Doxorubicin and amorphous calcium carbonate.

Haley Sproull extracts plant phytoliths for analysis with polarization microscopy, SEM-EDS and FT-IR spectroscopy.

Haley and her mentor, Chantel Tester, at the Regional Science Fair

200 nm

Undergraduate Research and OutreachDerk Joester, Northwestern University, DMR 1106208