A major objective of this work is to develop a cell-surface conjugation method with long-time stability under physiological conditions (37 0 C and pH 7.4) for several days. To our knowledge, the current stability of live cell conjugation, using artificial techniques that are hard to use for multiple cell types, is less than 72 hours. We incubated surface-modified Jurkat T cells at 37 o C and pH 7.4 for a period of 6 days by simply adding our cargo molecules to the culture. The images were recorded after 1, 3, and 6 days (Figure and figure ). Both the non-covalent and covalent cargo molecules show stability to the surface of the Jurkat T cells -as revealed by green fluorescence on the cell membrane after one day of conjugation but the covalent cargo molecule shows stability with more than 50% fluorescent remaining after six days in culture (Figure ). It is well known that activated T-cells result in lower surface redox levels with a reduced number of membrane thiol (-SH) groups. We verified the stability of our cargo with interleukin-2 (IL-2) activated Jurkat T cells (Figure ) suggesting the possible use of conjugated immune cell therapy as future applications. This data suggests long-time stability of the surface conjugation for the dual covalent and non-covalent conjugation compared to only non-covalent cell conjugation. To investigate whether the phosphate bearing groups of the covalent cargo have stable bonding with the cell surface functionality in a competing environment, we conjugated Jurkat T cells with fluorophore tag covalent cargo for 30 minutes and then washed with PBS. Next, the cells were treated with a covalent cargo molecule with no fluorophore tag (competing for similar bonding with florescent cargo molecules) for 30 minutes in growth media at 120 rpm at room temperature.