The multiple biological properties of nitric oxide (NO) has provided a basis of research of potential drug delivery platforms providing necessary stability and release characteristics that harness NO into an effective and safe dermal therapeutic agent. A major challenge has been the development of topical formulations that effectively deliver NO to the target site and are stable enough when stored. As the activity of NO is concentration- and duration-dependent, the use of light-triggered NO releasers represent an unprecedented strategy to deliver NO with exquisite spatiotemporal control. Here, we deliver a tailored lipophilic NO photoreleaser, based on a nitroaniline chromophore covalently linked to an aminobenzofurazane as a green fluorescent tag (ANBF), through PEGylated nanoparticles (NPs) made of a biodegradable di block copolymer of PEG and poly(?-caprolactone). In previous studies, association of these NPs with cyclodextrin derivatives was demonstrated to allow penetration through porcine ear skin. NPs prepared by a modified melting/sonication procedure displayed a size around 90 nm and a slightly negative zeta potential around -9 mV. ANBF was entrapped with high efficiency in NPs and remained strongly associated to hydrophobic core during the release in simulated biological fluids. To elucidate NP structure and to image NPs in the skin, NPs entrapping ANBF and prepared with Rhodamine B-labeled diblock (Rho-PCL-PEG) and triblock (Rho-PEG-PCL-PEG) copolymers were synthesized by click chemistry. NPs were designed to give Förster resonance energy transfer (FRET) between ANBF (donor) and Rhodamine B (acceptor). Fluorescence experiments demonstrated that FRET occurred only for NPs based on Rho-PCL-PEG, suggesting a core-shell structure where a hydrophobic PCL core accommodating ANBF is surrounded by a hydrophilic PEG shell. NO photo-release from the nitroaniline moiety occurred under the exclusive control of light (?exc = 405 nm) and was unaffected by the presence of Rhodamine B. In view of a skin delivery of ANBF, the use of an excitation wavelength shifted toward the infrared region would be a great advantage due to the deeper penetration of the red light in the tissue. Under two-photon excitation at 900 nm, Rhodamine B-labeled NPs evidenced an energy transfer between ANBF and rhodamine B-copolymer. Furthermore, two-photon imaging of human skin treated with ANBF-loaded Rhodamine B-labeled NPs showed that NPs could penetrate stratum corneum and release ANBF locally. Taken together, these results points at PEGylated PCL-PEG NPs as a dermal delivery system for lipophilic NO photodonors opening interesting perspectives in the treatment of skin diseases.
PEGylated biodegradable nanoparticles for dermal nitric oxide photodelivery
Paola Laurienzo;
2017
Abstract
The multiple biological properties of nitric oxide (NO) has provided a basis of research of potential drug delivery platforms providing necessary stability and release characteristics that harness NO into an effective and safe dermal therapeutic agent. A major challenge has been the development of topical formulations that effectively deliver NO to the target site and are stable enough when stored. As the activity of NO is concentration- and duration-dependent, the use of light-triggered NO releasers represent an unprecedented strategy to deliver NO with exquisite spatiotemporal control. Here, we deliver a tailored lipophilic NO photoreleaser, based on a nitroaniline chromophore covalently linked to an aminobenzofurazane as a green fluorescent tag (ANBF), through PEGylated nanoparticles (NPs) made of a biodegradable di block copolymer of PEG and poly(?-caprolactone). In previous studies, association of these NPs with cyclodextrin derivatives was demonstrated to allow penetration through porcine ear skin. NPs prepared by a modified melting/sonication procedure displayed a size around 90 nm and a slightly negative zeta potential around -9 mV. ANBF was entrapped with high efficiency in NPs and remained strongly associated to hydrophobic core during the release in simulated biological fluids. To elucidate NP structure and to image NPs in the skin, NPs entrapping ANBF and prepared with Rhodamine B-labeled diblock (Rho-PCL-PEG) and triblock (Rho-PEG-PCL-PEG) copolymers were synthesized by click chemistry. NPs were designed to give Förster resonance energy transfer (FRET) between ANBF (donor) and Rhodamine B (acceptor). Fluorescence experiments demonstrated that FRET occurred only for NPs based on Rho-PCL-PEG, suggesting a core-shell structure where a hydrophobic PCL core accommodating ANBF is surrounded by a hydrophilic PEG shell. NO photo-release from the nitroaniline moiety occurred under the exclusive control of light (?exc = 405 nm) and was unaffected by the presence of Rhodamine B. In view of a skin delivery of ANBF, the use of an excitation wavelength shifted toward the infrared region would be a great advantage due to the deeper penetration of the red light in the tissue. Under two-photon excitation at 900 nm, Rhodamine B-labeled NPs evidenced an energy transfer between ANBF and rhodamine B-copolymer. Furthermore, two-photon imaging of human skin treated with ANBF-loaded Rhodamine B-labeled NPs showed that NPs could penetrate stratum corneum and release ANBF locally. Taken together, these results points at PEGylated PCL-PEG NPs as a dermal delivery system for lipophilic NO photodonors opening interesting perspectives in the treatment of skin diseases.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
