| abstract |
Provided in some embodiments are compositions comprising a compound having a structure according to Formula A or Formula B: or a pharmaceutically acceptable salt, tautomer or hydrate thereof, where X2 is a bond or linker, X3 is bond or -PO4-, and X1, R1, R2, R3, and n are described herein. Also provided in some embodiments are methods for making and using such compounds and compositions. |