Intracellular aggregations of biological elements: From simple to complex

Most cellular elements could be functioned by forming aggregate structures through interactions with other molecules, which is like the luminescence mechanism of AIE molecules. However, in comparison to AIE molecules, the aggregation of biological elements appears to be more complex due to membership and mechanism, which is in line with the trend in biological evolution following the principle of simplicity to complexity. Here, we chose three distinctive examples because they differ significantly in their composition and show a progression from simple to complex, namely protein–protein complexes, protein–nucleic acid complexes, and protein–nucleic acid–lipid complexes. The majority of units that perform functions within cells belong to these three types. We discuss the formation mechanisms and related functions of the protein–protein complex (PML‐NB), the proteins–nucleic acids complex ribosome, and the proteins–nucleic acids–lipids complex exosome, and hope to provide expert insight for related fields.