Improving the brain delivery of gold nanoparticles by conjugation with an amphipathic peptide.

BACKGROUND & AIMS: Gold nanoparticles (GNPs) have promising applications for drug delivery as well as for the diagnosis and treatment of several pathologies, such as those related to the CNS. However, GNPs are retained in a number of organs, such as the liver and spleen. Owing to their negative charge and/or processes of opsonization, GNPs are retained by the reticuloendothelial system, thereby decreasing their delivery to the brain. It is therefore crucial to modify the nanoparticle surface in order to increase its lipophilicity and reduce its negative charge, thus achieving enhanced delivery to the brain. RESULTS: In this article, we have shown that conjugation of 12 nm GNPs with the amphipathic peptide CLPFFD increases the in vivo penetration of these particles to the rat brain. The C(GNP)-LPFFD conjugates showed a smaller negative charge and a greater hydrophobic character than citrate-capped GNPs of the same size. We administered intraperitoneal injections of citrate GNPs and C(GNP)-LPFFD in rats, and determined the gold content in the tissues by neutron activation. Compared with citrate GNPs, the C(GNP)-LPFFD conjugate improved the delivery to the brain, increasing the concentration of gold by fourfold, while simultaneously reducing its retention by the spleen 1 and 2 h after injection. At 24 h, the conjugate was partially cleared from the brain, and mainly accumulated in the liver. The C(GNP)-LPFFD did not alter the integrity of the blood-brain barrier, and had no effect on cell viability.

Synovial hemangioma in a dog.

OBJECTIVE: To report arthroscopic diagnosis and treatment of synovial hemangioma in a dog. STUDY DESIGN: Case report. ANIMAL: Standard Poodle (8-year-old neutered male). METHODS: A soft tissue density mass observed radiographically in the left stifle joint of a dog with a 2-month history of recurrent lameness, hemarthrosis, and a slight cranial drawer sign, was located by diagnostic arthroscopy and surgically excised via arthrotomy. RESULTS: Histologic evaluation revealed tissue composed of variably sized cavernous vascular spaces filled with erythrocytes that were considered compatible with synovial hemangioma. CONCLUSIONS: In this dog, synovial hemangioma evident as a soft tissue mass on radiographs was associated with chronic lameness and hemarthrosis, and resolved with surgical excision. CLINICAL RELEVANCE: Synovial hemangioma, although seemingly rare in dogs, should be considered in the differential diagnosis for nontraumatic, recurrent lameness, and unresponsive to anti-inflammatory therapy when there is a circumscribed intracapsular soft tissue mass evident radiographically together with hemarthrosis.