Next, an oligonucleotide with one Val-Ala(NB) incorporation (ODN4) was synthesized (Table ). After synthesis, ODN4 was deprotected with concentrated ammonia at room temperature for two hours, followed by HPLC purification. As shown in Figure Photolabile 2-nitrobenzyl is sensitive to exposure to ultraviolet (UV) light at 365 nm. Therefore, a 365 nm LED light was used to remove the 2nitrobenzyl group from ODN4 in water. As shown in Figure , after treatment with UV light for 5 minutes, ODN4 peak at 6.08 min completely disappeared, instead, a new DNA peak at 5.73 min was observed (Figure , blue line).