Self-assembly of PbS hollow sphere quantum dots via gas-bubble technique for early cancer diagnosis

► Large quantities of SO2 bubbles produced in the reaction system serve as the aggregation centers. ► After the initial nucleation, monomers would grow into NCs, which have a tendency to aggregate. ► Due to the minimization of interfacial energy, NCs aggregate around the gas-liquid interface. ► High emission intensity suggests immense potential of PbS QDs in early detection of cancer tumors.