The stability of quantum dots (QDs) in phosphate buffered saline (PBS) solutions plays an important role in the bio-applications. Red-emitting CdTe QDs with high PL efficiency were prepared using thiogliycolic acid as a capping agent. The assembly of the QDs in various buffer components was investigated. Using buffer components such as NaCl, KCl, and phosphate salts as scaffolds, the assembly of CdTe QDs occurred on a slide glass in the re-crystalline process of buffer components. The QDs were homogeneously assembled into the composites with leaf or flake shapes. The result is utilizable for pattern manufacture in applications and domain growth was developed to test the change of photoluminescence (PL) properties and self-assembly of the QDs to form fractal structures. Compared with initial CdTe QD solutions, the PL spectrum of the QDs in the composite is narrowed. The stability test indicated that H₂PO-₄ and HPO2-₄ ions play important roles to decrease the PL of the QDs in PBS buffer solvents.