Flavonoid is one of the polyphenolic molecule from natural species such as fruit and plant. Bio-inspired compound, catechin, is one of the component from green tea and other plants. Catechin as well as other flavonoids are generally known for their advantageous properties such as anti-inflammation, anti-oxidant, and anti-cancer effects. Many flavonoids are poorly soluble in water which is a critical drawback to be used in bio-applications. In this study, we increased aqueous solubility of catechin through formation of complex with poly(ethylene glycol) (PEG). The experimental procedure does not require chemical crosslinker or initiator. The preparation is simple but the solubility enhancement is high (at least 50 mg/ml). Nanocomlex of catechin is used in in-vivo to treat dry eye model. The nanocomplex showed anti-inflammation property and increased goblet cell density which helps dry eye diseases.