Preparation of fluorescent microspheres via layer-by-layer self-assembly

The fluorescent marker in the drug delivery system (DDS) is very critical to achieve dynamic tracing of drug. However, the DDS embedded with fluorescent materials is not capable of detecting the release of drug precisely, since the separated fluorescent substrate and drug do not release and diffuse simultaneously. To increase the accuracy of tracing drug, we prepared fluorescent-labeling drug Gd(aspirin)3·2H2O by covalent binding of rare earth ion Gd3+ with aspirin. Fe3O4 magnetic nanoparticles as the magnetic targeting carrier and Gd(aspirin)3·2H2O as the fluorescent-labeling drug were incorporated into chitosan microspheres to prepare magnetic and fluorescent chitosan microspheres as a DDS. Investigated by Fourier transform infrared spectrometer, Varioskan Flash, X-ray diffraction, vibrating sample magnetometer, transmission electron microscope, and scanning electron microscope, the DDS with fluorescent-labeling drug showed good fluorescent and magnetic properties.