Lin, J.; Sun, T.; Wei, Y.; Xue, C.; Xu, G.; Chen, P.; Wang, Y.; Yang, S.; Cavazos, C.; Shen, C.; Wang, A.; Wang, A.; Zhang, K.

Oligonucleotide therapeutics hold transformative potential, yet their clinical translation is hindered by delivery barriers, including rapid renal/hepatic clearance and poor organ specificity. Bottlebrush polymers conjugates have emerged as a promising vector to address these limitations, but conventional architectures with uniform backbones can only achieve an unmodifiable, rigid biodistribution profile. Here, we report a library of sequence-defined digital bottlebrush polymers, precisely engineered with controlled placements of chemical motifs that modify physiochemical properties - including lipids, cholesterol, and cationic groups - along a polyphosphodiester backbone. Systematic evaluation of the digital bottlebrush polymer library reveals distinct structure-property relationships and enables organ-biased systemic delivery to several traditionally difficult-to-reach tissues, including muscle and skin. In a mouse model of rheumatoid arthritis, a single dose of a spleen-homing polymer-conjugated antisense oligonucleotide targeting TNF- achieves potent knockdown and drives full functional recovery. These findings establish a versatile design framework for tailoring bottlebrush polymers to specific therapeutic applications.