This work reports the development of porous poly (ε-caprolactone) (PCL)-based intraocular implants, prepared by green supercritical carbon dioxide (scCO₂) foaming/mixing method (SFM), to produce implants that degrade faster than typical slow-degrading PCL-based implants. The higher porosities and surface areas of these implants led to faster degradation rates at in vitro accelerated alkaline conditions than low porosity/surface area implants prepared by hot melting processing. These porous implants also presented distinct (faster) release rates of a test-drug (dexamethasone). Additionally, these porous devices did not cause cell death and did not reduce the number of neurons, indicating that are not toxic to retinal cells. We further explored the impact of PCL-based implant to the retina by in vivo evaluation and histological analysis. Implants were surgically inserted in the vitreous of Wistar rats, and their presence did not change the function, structure and anatomy of the retina. These devices demonstrated a good intraocular tolerance, further confirming their viability for prolonged drug delivery applications. Further comprehensive studies based on this promising preliminary assessment and proof-of-concept could enable its future translation to clinical protective strategies for retinal diseases.

A novel, nitrate-free, combustion method has been developed to prepare Ni–BaZr_0.85Y_0.15O_3−δ (Ni–BZY) cermet anodes for proton ceramic fuel cells. Nickel acetate and 30% H₂O₂ were used as starting precursors for the combustion reaction into which pre-prepared BZY powders were dispersed. The advantages of this nitrate-free combustion method have been demonstrated by comparison to a more common nitrate/glycine combustion route. The results demonstrate that use of the nitrate-free precursors is essential to avoid partial decomposition of the pre-prepared BZY phase. Employment of the more common nitrate-based precursors, due to their acidic nature, results in removal of Ba from the perovskite phase and formation of Ba(NO₃)₂, subsequently leading to the presence of BaY₂NiO₅ in the final product. The impact of Ni–BZY phase purity on resultant polarisation behaviour has been assessed as a function of water vapour and oxygen partial pressures for electrodes of comparable microstructure. Partial decomposition of the perovskite phase limits performance by increasing the higher frequency polarisation resistance and this phenomenon is suggested to be associated with impaired proton transport in the oxide cermet phase. The novel actetate–H₂O₂ combustion method here described may be of interest for the formation of other ceramic oxide materials, offering economical advantages over more classical nitrate-based combustion routes, as well as significant environmental benefits due to the avoidance of releasing NO_x gases.

Retinal ganglion cell (RGC) loss underlies several conditions which give rise to significant visual compromise, including glaucoma and ischaemic optic neuropathies. Neuroprotection of RGCs is a clinical well-defined unmet need in these diseases, and adenosine A₃ receptor (A₃R) activation emerges as a therapeutic pharmacological approach to protect RGCs. A porous biodegradable intraocular implant loaded with 2-Cl-IB-MECA (selective A₃R agonist) was used as a strategy to protect RGCs. Drug-loaded PCL implants released 2-Cl-IB-MECA for an extended period and the released 2-Cl-IB-MECA limited glutamate-evoked calcium (Ca²⁺) rise in RGCs. Retinal thinning due to transient ischemia was not prevented by 2-Cl-IB-MECA-PCL implant. However, 2-Cl-IB-MECA-PCL implants decreased retinal cell death, promoted the survival of RGCs, preserved optic nerve structure and anterograde axonal transport. We further demonstrated that 2-Cl-IB-MECA-loaded PCL implants were able to enhance RGC function that was compromised by transient ischemia. Taking into consideration the beneficial effects afforded by 2-Cl-IB-MECA released from the PCL implant, this can be envisaged a good therapeutic strategy to protect RGCs.