RESUMO
Vesicles made from synthetic diblock copolymers, polymersomes, have great potential for targeted imaging and drug delivery. Ultrasound is gaining attention as a therapeutic tool in addition to its use in diagnostics. We report on the response of nanoscale vesicles made from PEO-b-PBD copolymers to ultrasound at 20 kHz. Leakage of a fluorescent dye from vesicle core was measured to study the permeation. Ultrasound causes significant leakage from the core above threshold intensity, suggesting that leakage is governed by acoustic cavitation. Size measurements and direct visualization of vesicles show that ultrasound does not completely rupture them into fragments but causes transient poration. The extent of leakage inversely depends on membrane thickness and directly depends on sonication time and intensity.
Assuntos
Butadienos/química , Preparações de Ação Retardada/química , Sistemas de Liberação de Medicamentos/métodos , Nanocápsulas/química , Nanosferas/química , Polietileno/química , Sonicação , Ultrassom , Corantes Fluorescentes/química , Corantes Fluorescentes/metabolismo , Bicamadas Lipídicas/química , PermeabilidadeRESUMO
Self-assembled nanostructures obtained from natural and synthetic amphiphiles serve as mimics of biological membranes and enable the delivery of drugs, proteins, genes, and imaging agents. Yet the precise molecular arrangements demanded by these functions are difficult to achieve. Libraries of amphiphilic Janus dendrimers, prepared by facile coupling of tailored hydrophilic and hydrophobic branched segments, have been screened by cryogenic transmission electron microscopy, revealing a rich palette of morphologies in water, including vesicles, denoted dendrimersomes, cubosomes, disks, tubular vesicles, and helical ribbons. Dendrimersomes marry the stability and mechanical strength obtainable from polymersomes with the biological function of stabilized phospholipid liposomes, plus superior uniformity of size, ease of formation, and chemical functionalization. This modular synthesis strategy provides access to systematic tuning of molecular structure and of self-assembled architecture.
Assuntos
Dendrímeros/química , Membranas Artificiais , Nanoestruturas , Antibióticos Antineoplásicos/administração & dosagem , Materiais Biomiméticos/química , Microscopia Crioeletrônica , Doxorrubicina/administração & dosagem , Portadores de Fármacos , Interações Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Simulação de Dinâmica Molecular , Estrutura Molecular , Propriedades de Superfície , Tensoativos/química , ÁguaRESUMO
Biodegradable polymersomes are promising vehicles for a range of applications. Their stabilization would improve many properties, including the retention and controlled release of polymersome contents, yet this has not been previously accomplished. Here, we present the first example of stabilizing fully biodegradable polymersomes through acrylation of the hydrophobic terminal end of polymersome-forming poly(caprolactone-b-ethylene glycol). Exposure of the resulting polymersomes loaded with a hydrophobic photoinitiator to ultraviolet light polymerized the acrylates, without affecting polymersome morphology or cell cytotoxicity. These stabilized polymersomes were more resistant to surfactant disruption and degradation. As an example of stabilized polymersome utility, the unintended release of doxorubicin (DOX) due to leakage from polymersomes decreased with membrane stabilization and slower sustained release was observed. Finally, DOX-loaded polymersomes retained their cytotoxicity following stabilization.
Assuntos
Materiais Biocompatíveis/química , Doxorrubicina/química , Polímeros/química , Animais , Etilenoglicóis/química , Fibroblastos/metabolismo , Luz , Espectroscopia de Ressonância Magnética , Camundongos , Microscopia Eletrônica de Transmissão/métodos , Células NIH 3T3 , Fotoquímica/métodos , Poliésteres/química , Espectrofotometria Ultravioleta/métodos , Propriedades de Superfície , TensoativosRESUMO
Dendritic cells (DCs) play a pivotal role in both immune tolerance and the initiation of immunological responses. The ability to track DCs in vivo is imperative for the development of DC-based cellular therapies and to advance our understanding of DC function and pathophysiology. Here, we conjugate a cell permeable peptide, Tat, to near-infrared (NIR) emissive polymersomes in order to enable efficient intracellular delivery for future DC tracking with these optical probes. NIR imaging allows quantitative, repetitive, in vivo detection of fluorophore-laden cells, at centimeter tissue depths without disturbing cellular function. Flow cytometry and confocal microscopy results indicate that Tat-mediated polymersome delivery to DCs is concentration and time dependent, resulting in punctate intracellular localization. Further, loading cells with Tat NIR emissive polymersomes does not interfere with cytokine-induced DC maturation and has modest effects on DC viability, but has a significant effect on mature DC-induced activation of naive T cells. We observe significant uptake of NIR emissive polymersomes when conjugated to the peptide, with a lower detection limit of 5000 labeled DCs. The extent of polymersome delivery is estimated as 70 000 +/- 10 000 vesicles/cell, equivalent to 0.7 +/- 0.1 fmol of NIR fluorophore. Our studies will enable future in vivo tracking of ex vivo labeled DCs by NIR fluorescence based imaging.