All folate samples show two peaks at 285nm and 360nm, respectively. NPs- NH2 shows strong UV-vis absorption at wavelengthsbelow 275 nm. NPs-folate demonstrates UV-vis absorption peaks at 285nm and 360nm, which contribute from covalently bounded folate

Figure 2: UV-vis absorption spectra of folate in different concentration (0.001mg/ml, 0.0025mg/ml, 0.005mg/ml, 0.01mg/ml), NPs-folate (0.5mg/ml), and NPs-NH2(0.5mg/ml).