Engineering colloidal systems for cell manipulation, delivery, and tracking

Men-made colloidal systems are widely presented across various aspects of biomedical science. There is a strong demand for engineering colloids to tailor their functions and properties to meet the requirements of biological and medical tasks. These requirements are not only related to size, shape, capacity to carry bioactive compounds as drug delivery systems, and the ability to navigate via chemical and physical targeting. Today, the more challenging aspects of colloid design are how the colloidal particles interact with biological cells, undergo internalization by cells, how they reside in the cell interior, and whether we can explore cells with colloids, intervene with biochemical processes, and alter cell functionality. Cell tracking, exploitation of cells as natural transporters of internalized colloidal carriers loaded with drugs, and exploring physical methods as external triggers of cell functions are ongoing topics in the research agenda. In this review, we summarize recent advances in these areas, focusing on how colloidal particles interact and are taken up by mesenchymal stem cells, dendritic cells, neurons, macrophages, neutrophils and lymphocytes, red blood cells, and platelets. The engineering of colloidal vesicles with cell membrane fragments and exosomes facilitates their application. The perspectives of different approaches in colloid design, their limitations, and obstacles on the biological side are discussed.