Synthesis and Magnetic Properties of Carbon Doped and Reduced SrTiO3 Nanoparticles

We report on the studies of the synthesis, structural, and magnetic properties of undoped SrTiO3 (STO), carbon-doped STO:C, and reduced STO STO:R nanoparticles. Fine (similar to 20-30 nm) and coarse (similar to 100 nm) nanoparticles with a single phase of cubic perovskite-type structure were sintered by thermal decomposition of SrTiO(C2O4)(2). Magnetization loops of fine STO:C and STO:R nanoparticles at low temperatures and an almost linear decrease in magnetization with temperature indicate the realization of a soft, ferromagnetic state in them, with a pronounced disorder effect characteristic of doped dilute magnetic semiconductors. Oxidation and particle size increase suppress the magnetic manifestations, demonstrating the importance of surface-related defects and oxygen deficiency in the emergence of magnetism. It was found that oxygen vacancies and doping with carbon make similar contributions to the magnetization, while complementary electron paramagnetic resonance, together with magnetization measurement studies, show that the most probable state of oxygen vacancies, which determine the appearance of magnetic properties, are charged F+ oxygen vacancies and C-impurity centers, which tend to segregate on the surface of nanoparticles

AAV-mediated photoreceptor transduction of the pig cone-enriched retina

Recent success in clinical trials supports the use of adeno-associated viral (AAV) vectors for gene therapy of retinal diseases caused by defects in the retinal pigment epithelium (RPE). In contrast, evidence of the efficacy of AAV-mediated gene transfer to retinal photoreceptors, the major site of inherited retinal diseases, is less robust. In addition, although AAV-mediated RPE transduction appears efficient, independently of the serotype used and species treated, AAV-mediated photoreceptor gene transfer has not been systematically investigated thus so far in large animal models, which also may allow identifying relevant species-specific differences in AAV-mediated retinal transduction. In the present study, we used the porcine retina, which has a high cone/rod ratio. This feature allows to properly evaluate both cone and rod photoreceptors transduction and compare the transduction characteristics of AAV2/5 and 2/8, the two most efficient AAV vector serotypes for photoreceptor targeting. Here we show that AAV2/5 and 2/8 transduces both RPE and photoreceptors. AAV2/8 infects and transduces photoreceptor more efficiently than AAV2/5, similarly to what we have observed in the murine retina. The use of the photoreceptor-specific rhodopsin promoter restricts transgene expression to porcine rods and cones, and results in photoreceptor transduction levels similar to those obtained with the ubiquitous promoters tested. Finally, immunological, toxicological and biodistribution studies support the safety of AAV subretinal administration to the large porcine retina. The data presented here on AAV-mediated transduction of the cone-enriched porcine retina may affect the development of gene-based therapies for rare and common severe photoreceptor diseases

Synthesis and Magnetic Properties of Carbon Doped and Reduced SrTiO₃ Nanoparticles

We report on the studies of the synthesis, structural, and magnetic properties of undoped SrTiO3 (STO), carbon-doped STO:C, and reduced STO STO:R nanoparticles. Fine (~20–30 nm) and coarse (~100 nm) nanoparticles with a single phase of cubic perovskite-type structure were sintered by thermal decomposition of SrTiO(C2O4)2. Magnetization loops of fine STO:C and STO:R nanoparticles at low temperatures and an almost linear decrease in magnetization with temperature indicate the realization of a soft, ferromagnetic state in them, with a pronounced disorder effect characteristic of doped dilute magnetic semiconductors. Oxidation and particle size increase suppress the magnetic manifestations, demonstrating the importance of surface-related defects and oxygen deficiency in the emergence of magnetism. It was found that oxygen vacancies and doping with carbon make similar contributions to the magnetization, while complementary electron paramagnetic resonance, together with magnetization measurement studies, show that the most probable state of oxygen vacancies, which determine the appearance of magnetic properties, are charged F+ oxygen vacancies and C-impurity centers, which tend to segregate on the surface of nanoparticles

Lighting a candle in the dark: advances in genetics and gene therapy of recessive retinal dystrophies

Nonsyndromic recessive retinal dystrophies cause severe visual impairment due to the death of photoreceptor and retinal pigment epithelium cells. These diseases until recently have been considered to be incurable. Molecular genetic studies in the last two decades have revealed the underlying molecular causes in approximately two-thirds of patients. The mammalian eye has been at the forefront of therapeutic trials based on gene augmentation in humans with an early-onset nonsyndromic recessive retinal dystrophy due to mutations in the retinal pigment epithelium–specific protein 65kDa (RPE65) gene. Tremendous challenges still lie ahead to extrapolate these studies to other retinal disease–causing genes, as human gene augmentation studies require testing in animal models for each individual gene and sufficiently large patient cohorts for clinical trials remain to be identified through cost-effective mutation screening protocols