A biodegradable device for activating T-cells and a method for differentiation of T-cells using the device are disclosed, wherein, the device comprises an universal crosslinking agent comprising a biodegradable support coated with a first material, wherein the first material is capable of crosslinking more than one array of second materials, the second materials capable of binding T-cell surface moieties to deliver a signal to the T-cells, wherein each successive array of second materials has at least one second material different from the preceding array of second materials.
