Nanorod Polymers: Nanoparticles and colloids have been used to model crystallization and melting phenomena. Liu et al. (p. 197 ) studied the polymerization kinetics of nanoparticles. Functionalized arrowhead nanorods acted as linkable units that joined together in solvent-tuned assembly. The results resembled common processes of chemical polymerization: Growth was controlled kinetically and could be interpreted by formulas for step-growth polymerization and branching. Furthermore, some isomerization phenomena were observed, as was the formation of cyclic “macromolecules.”

Man-made biomimetic hydrogels with tunable biophysical and biochemical properties can support the growth of microtumors.