Faculty Sponsor's Department:
In the field of medicine, there arises a need for delivering medication to specific portions in organisms. One solution for simulating site-specific drug delivery is through mesoporous microspheres, which can be loaded with various lanthanide down-conversion nanoparticles and organic dyes and coated with pH sensitive soy proteins. These particles are both excited with 980 nm near infrared radiation (NIR) and emit different excitation wavelengths; however, when they are both present in the microsphere, concentration quenching causes the emission of the down-conversion nanocrystals (DCNC) to be undetectable. This project takes advantage of this property to simulate drug delivery in organisms with pH-responsive drug carriers. In acidic environments of an organism – such as the stomach, the positively charged amine group on the soy protein and the deprotonated carboxyl group on the microsphere are attracted via electrostatic forces, keeping the loaded materials in the microsphere. Yet, in more basic environments – which correspond to the desired location of drug release, such as the intestinal region – the amino-carboxyl bond breaks to release the organic dyes; the dyes diffuse in a manner similar to drugs, while the nanoparticles remain in the mesoporous microsphere casing. Then, upon NIR excitation, both sets of particles emit their respective excitation wavelength to show the location of the drugs and the drug carrier.