Cotton stalk derived lignin-based hydrogel and its therapeutic utility in diabetic retinopathy

Cotton stalk waste from agriculture has been shown to be a rich source of cellulose and lignin. In our study, we have developed the lignin-based hydrogel for the treatment of diabetic retinopathy (DR). Lignin's natural antioxidant and anti-inflammatory properties complement its function as a drug carrier, especially in conditions where oxidative stress and inflammation play a significant role, as in DR. The developed bioinspired hydrogel acts as a drug delivery vehicle for natural polyphenolic antioxidants like curcumin, naringenin and alpha-lactalbumin, which have beneficial therapeutic effects in DR due to their diverse therapeutic action. By taking complementary advantages of lignin, the therapeutic application of the developed lignin-based hydrogel with actives was studied in the treatment of DR, and in vitro characterization was performed with DLS, XRD, DSC,¹HNMR, ATR-IR, and SEM analysis. The particle size of extracted lignin was found to be 282.8 nm by the DLS method, which is suitable for ocular delivery. ATR-IR analysis confirms the lignin functional groups. XRD revealed the amorphous nature of hydrogels. DSC revealed that lignin-based hydrogel was able to protect active molecules from thermal degradation. In vivo results confirmed the suppressed VEGF level in the vitreous fluid after 4 weeks of treatment. The proposed therapeutic lignin-based hydrogel possesses dose-dependent activity, which overcomes the major limitations of current treatment in DR, and advantages like self-administration, pocket friendly, non-invasive and painless treatment.