New CO2-philic hydrocarbon molecules were synthesized by reversible addition fragmentation chain-transfer polymerization. These poly(vinyl alkylates) show the highest solubility in supercritical CO2 of any hydrocarbon reported to date. By utilizing the anchoring ability of the thiocarbonylthio end group, the dispersion polymerization of N-vinyl pyrrolidone was successfully achieved in scCO2 leading to high yields of well-defined spherical polymer particles.

Fluorinated macro-RAFT agents can act as in situ stabilisers while exhibiting good control over block copolymers formed by dispersion polymerisation in supercritical CO2 to yield well-defined spherical particles with a fluorinated "halo".

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Two methodologies for synthesizing novel, degradable, core cross-linked copolymer particles were investigated and the molecular properties of the resultant polymers were compared. The first approach was to synthesize hyperbranched poly(ε-caprolactone-co-N,N-dimethylamino-2-ethyl methacrylate (PCL-co-PDMAEMA) by combining metal-catalyzed ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) and reversible additionfragmentation chain transfer polymerization (RAFT) of N, N-dimethylamino-2-ethyl methacrylate. First, the hyperbranched core was prepared via ROP copolymerization of ε-CL and branching agent 4,4-bioxepanyl-7,7-dione (BOD). This polymerization was initiated using the hydroxyl moiety of the bifunctional initiator 4-cyano-1-hydroxypent-4-yl dithiobenzoate (ACP-RAFT) which resulted in reactive pendent RAFT groups located on the polymer chains. The hyperbranched structure was confirmed by GPC-MALLS and NMR. Subsequent chain extension of this hyperbranched macromolecule with DMAEMA using RAFT chemistry yielded water-soluble nanoparticles. The second method involved the synthesis of core-cross-linked-shell particles (CCS) by the arm-first route. Linear arms of DMAEMA were synthesized using ACP-RAFT and subsequently used as macroinitiator for the ROP of ε-CL and BOD to form a degradable microgel that was water-soluble. Once again, molecular structure was analyzed by 1 H NMR, 13 C NMR, and GPC and molecular size by TEM. Finally, GPC-MALLS was used to qualitatively investigate the different crosslink densities of the degradable core by the two different methodologies. Thus, we demonstrate two synthetic approaches for constructing water-soluble, degradable core-shell nanoparticles that exhibit varying degrees of cross-linking by combining RAFT and ROP.

Purpose To analyze polyesteramide (PEA) microparticles (“MPs”) interaction with reagents used in histological analysis and their compatibility with the steps required for ocular injection. Methods Unloaded‐ and dye‐loaded (Chromoionophore II) PEA III MPs suspended in PBS/mannitol were: i) analyzed under light and fluorescence optic microscopy; ii) exposed to reagents, solutions and processes required to perform histological procedures; iii) released through different needle gauges and quantified in a Neubauer chamber. Rat eyes were divided into two groups: intravitreal injection (n= 20) and subtenon/subconjuntival injection (n=24). After sacrifice, tissues were processed as retinal whole‐mount and cryosections. Results i) PEA III MPs were stable when contacted with distilled water, PBS, 4% PF and 2% glutaraldehyde; ii) PEA III MPs lost shape or dissolved when in contact with Xylene, EtOH or acetone; iii) freezing at ‐20ºC and heating at 60ºC does not impact particles re‐dispersion, shape and polydispersity; iv) no significant differences in MPs number released through different needle gauges (25G, 27G, 30G, 32G) were found; v) in unstained tissues, MPs preserved their morphological characteristics and coalesced into depots. Conclusion MPs: i) are compatible with some of the steps required for routine histological processing. ii) can be released through needle gauges used in human clinical setting; iii) the injection should be done during the 30 minutes following suspension preparation.

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