This is the first step for development of a polyanhydride-based core-shell microparticle for single-injection vaccine delivery. The overall goal of this project is to develop a polyanhydride-based core-shell microparticle platform for diphtheria toxoid vaccine delivery with single-injection administration. This image artistically symbolized the launching of my PhD study by learning a series of fabrication techniques that I have never learned about, and this is also one of my first projects as a PhD student. Starting from this particle, I enhanced my skills and made more batches for in vitro and in vivo studies. This was a tiny and not perfectly shaped particle, but it was a big and firm step for my career and personal growth.