Preparation and characterization of functional inorganic/organic composite microspheres via electrostatic interaction

In this paper, a simple approach was presented to prepare functional inorganic/organic composite microspheres in which the inorganic nanoparticles were encapsulated into the polyelectrolyte complexes between chitosan (CS) and poly(aspartic acid) sodium salt (PAsp). The magnetic microspheres were prepared via electrostatic interaction between the citrate groups stabilizing Fe(3)O(4) nanoparticles and the amino groups of CS. Being taken as a kind of special polyelectrolyte with high molecular weight, the inorganic nanoparticles presented strong interaction with polyelectrolyte. By tuning the unit molar ratio of the opposite charged polyelectrolytes and the amount of Fe(3)O(4) nanoparticles, the structure of the composite microspheres could be controlled and the dimension of microspheres ranged from 110 nm to 320 nm. Then the approach was extended to prepare luminescent-magnetic CS-PAsp microspheres by encapsulated Fe(3)O(4) nanoparticles and CdTe quantum dots synchronously, which exhibited superior pH stability and remained strong photoluminescence properties after crosslinking. The CdTe-Fe(3)O(4)/CS-PAsp composite microspheres are potentially useful for further application in biolabeling and imaging.