There is provided a polymer comprising: (i) a repeat unit derived from a compound of formula (I) (Formula (I)) wherein, R1 and R2 are each independently selected from OH, OR′, SH, SR′, NH2, NHR′ and NR′2; R′ is C1-20 hydrocarbyl; each n is independently 0 or an integer between 1 and 6; each m is independently 0 or an integer between 1 and 4, and preferably at least one m is 1; and q is an integer between 1 and 8; and; (ii) a biologically active molecule, wherein said biologically active molecule is covalently bonded to said repeat unit; as well as methods for preparing such polymers, particles comprising said polymers and uses of said polymers and particles including use in the treatment of disease.