Control in ROP allows polymers to be synthesized with a wide range of architectures and self-assembly properties.

The size, shape, and underlying chemistries of drug delivery particles are key parameters which govern their ultimate performance in vivo. Responsive particles are desirable for triggered drug delivery, achievable through architecture change and biodegradation to control in vivo fate. Here, polymeric materials are synthesized with linear, hyperbranched, star, and micellar-like architectures based on 2-hydroxypropyl methacrylamide (HPMA), and the effects of 3D architecture and redox-responsive biodegradation on biological transport are investigated. Variations in "stealth" behavior between the materials are quantified in vitro and in vivo, whereby reduction-responsive hyperbranched polymers most successfully avoid accumulation within the liver, and none of the materials target the spleen or lungs. Functionalization of selected architectures with doxorubicin (DOX) demonstrates enhanced efficacy over the free drug in 2D and 3D in vitro models, and enhanced efficacy in vivo in a highly aggressive orthotopic breast cancer model when dosed over schedules accounting for the biodistribution of the carriers. These data show it is possible to direct materials of the same chemistries into different cellular and physiological regions via modulation of their 3D architectures, and thus the work overall provides valuable new insight into how nanoparticle architecture and programmed degradation can be tailored to elicit specific biological responses for drug delivery.

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Amphiphilic block co-polymers composed of poly(ethylene glycol)-co-poly(lactide)-co-poly(2-((tert-butoxycarbonyl)amino)-3-propyl carbonate) (PEG-pLA-pTBPC) are synthesized in monomer ratios and arrangements to enable assembly into nanoparticles with different sizes and architectures. These materials are based on components in clinical use, or known to be biodegradable, and retain the same fundamental chemistry across "AB" and "BAB" block architectures. In MCF7 and MDA-MB-231 breast cancer cells, nanoparticles of <100 nm are internalized most rapidly, by both clathrin-and caveolin-mediated pathways. In THP-1 cells, polymer architecture and length of the hydrophilic block is the most important factor in the rate of internalization. The organ distributions of systemically injected nanoparticles in healthy mice indicate highest accumulation of the BAB-blocks in lungs and liver and the lowest accumulation in these organs of a methoxyPEG 5000-pLA-pTBPC polymer. Conjugation of doxorubicin via a serum-stable urea linker to the carbonate regions of PEG 5000-pLA-pTBPC generates self-assembling nanoparticles which are more cytotoxic in 2D, and penetrate further in 3D spheroids of triple negative breast cancer cells, than the free drug. In an aggressive orthotopic triple negative breast cancer mouse model, the methoxyPEG 5000-pLA-pTBPC is of similar potency to free doxorubicin but with no evidence of adverse effects in terms of body weight.