Designed proteinoid polymers and nanoparticles encapsulating risperidone for enhanced antipsychotic activity

BACKGROUND

Nanoparticles (NPs) incorporating drug formulations can be used to facilitate passage through biological barriers including the blood-brain barrier (BBB) and increase drug delivery and bioavailability. Hence, NP-based administration may enhance the efficiency of current antipsychotics. Encapsulation within NPs can resolve aqueous solubility problems that not only reduce permeability through the BBB but also affect targeting. The present study describes a new drug delivery system based on proteinoid NPs to explore the possibility of improving drug efficacy. Risperidone (RSP) is a commonly used atypical antipsychotic medication, and was therefore selected for encapsulation by proteinoid NPs.

RESULTS

Proteinoid polymers with high molecular weight and low polydispersity were synthesized from L-amino acids and poly-L-lactic acid (PLLA) by thermal step-growth polymerization mechanism. RSP-loaded proteinoid NPs were then prepared using a self-assembly process in the presence of RSP, followed by PEGylation. The optimal PEGylated RSP-loaded NPs were characterized in terms of diameter and size distribution, drug loading, ζ-potential, cytotoxicity, biodistribution, and psychopharmacological effects. The findings indicate significantly higher antipsychotic activity of drug-loaded proteinoid NPs compared to free RSP.

CONCLUSIONS

Proteinoid NPs enhance RSP delivery and may potentially increase drug efficiency by reducing dosage and side effects.

Targeted drug delivery of near IR fluorescent doxorubicin-conjugated poly(ethylene glycol) bisphosphonate nanoparticles for diagnosis and therapy of primary and metastatic bone cancer in a mouse model

BACKGROUND

Most primary and metastatic bone tumors demonstrate increased osteoclast activity and bone resorption. Current treatment is based on a combination of surgery, radiotherapy and chemotherapy. Severe side effects are associated with chemotherapy due to use of high dosage and nonspecific uptake. Bisphosphonates have a strong affinity to Ca2+ ions and are widely used in the treatment of bone disorders.

RESULTS

We have engineered a unique biodegradable bisphosphonate nanoparticle (NPs) bearing two functional surface groups: (1) primary amine groups for covalent attachment of a dye/drug (e.g. NIR dye Cy 7 or doxorubicin); (2) bisphosphonate groups for targeting and chelation to bone hydroxyapatite. In addition, these engineered NPs contain high polyethyleneglycol (PEG) concentration in order to increase their blood half life time. In vitro experiments on Saos-2 human osteosarcoma cell line, demonstrated that at a tenth of the concentration, doxorubicin-conjugated bisphosphonate NPs achieved a similar uptake to free doxorubicin. In vivo targeting experiments using the NIR fluorescence bisphosphonate NPs on both Soas-2 human osteosarcoma xenograft mouse model and orthotopic bone metastases mCherry-labeled 4T1 breast cancer mouse model confirmed specific targeting. In addition, therapeutic in vivo experiments using doxorubicin-conjugated bisphosphonate NPs demonstrated a 40% greater inhibition of tumor growth in Saos-2 human osteosarcoma xenograft mouse model when compared to free doxorubicin.

CONCLUSIONS

In this research we have shown the potential use of doxorubicin-conjugated BP NPs for the targeting and treatment of primary and metastatic bone tumors. The targeted delivery of doxorubicin to the tumor significantly increased the efficacy of the anti-cancer drug, thus enabling the effective use of a lower concentration of doxorubicin. Furthermore, the targeting ability of the BP NPs in an orthotopic xenograft mouse model reinforced our findings that these BP NPs have the potential to be used for the treatment of primary and metastatic bone cancer.

Near IR fluorescent conjugated poly(ethylene glycol)bisphosphonate nanoparticles for in vivo bone targeting in a young mouse model

Bisphosphonate (BP) compounds are widely used in the treatment of bone disorders. This group of drugs with a high affinity to Ca⁺² ions is rapidly attracted to bone mineral, especially in areas of high resorption. We have engineered unique biodegradable BP nanoparticles (NPs) by dispersion co-polymerization of the monomers methacrylate-PEG-BP) and (3-Aminopropyl)mathacrylamide) with the crosslinker monomer tetra ethylene glycol diacrylate. These NPs possess a dual functionality: (1) covalent attachment of a dye (e.g. near IR dye) or a drug to the nanoparticles through the primary amine groups on the surface of the NPs; (2) chelation to the bone mineral hydroxyapatite through the BP on the surface of the NPs. This study describes the uptake of the unique near IR fluorescent Cy 7-conjugated BP NPs in bone of a young mouse model. Blood half-life studies revealed a relatively long half-life (approximately 5 h) due to a high concentration of PEG in the BP NPs as well as a relatively long whole body clearance (approximately 2 weeks). Body distribution studies showed a specific uptake of the BP NPs in bone. These unique engineered BP NPs are planned to be utilized in future work for diagnostic and drug delivery systems that are targeted to bone disorders.

Stabilization of monodomain polarization in ultrathin PbTiO3 films

Using in situ high-resolution synchrotron x-ray scattering, the Curie temperature TC has been determined for ultrathin c-axis epitaxial PbTiO3 films on conducting substrates (SrRuO3 on SrTiO3), with surfaces exposed to a controlled vapor environment. The suppression of TC was relatively small, even for the thinnest film (1.2 nm). We observe that 180 degrees stripe domains do not form, indicating that the depolarizing field is compensated by free charge at both interfaces. This is confirmed by ab initio calculations that find polar ground states in the presence of ionic adsorbates.

The ZIC gene family in development and disease

The human ZIC gene family is comprised of five members encoding zinc-finger transcription factors, which are the vertebrate homologs of the Drosophila odd-paired gene. Mutations in ZIC genes in humans have recently been implicated in a wide variety of congenital malformations, including Dandy-Walker malformation, holoprosencephaly, neural tube defects, and heterotaxy. Mutant analysis of these genes in mice has underscored the conserved developmental roles of these genes. Further, this analysis has begun to elucidate the molecular and developmental mechanisms underlying these important birth defects.

Aorto-right ventricular fistula: a late complication of aortic valve replacement

We report the case of a patient who was found to have an aorto-right ventricular fistula 17 years after receiving a Björk-Shiley prosthetic aortic valve. A pseudoaneurysm had formed at the aortotomy suture line, and it had extended into the interventricular septum and had eventually opened into the right ventricle. Using transesophageal echocardiography, we identified the defect in the ascending aorta, and a left-to-right shunt. Aortography was used to confirm these findings. The pseudoaneurysm was successfully resected and the ascending aorta was replaced with a Dacron graft. To the best of our knowledge, no similar late complication of aortic valve replacement has been reported in the medical literature.

Fluorescent virions: dynamic tracking of the pathway of adenoviral gene transfer vectors in living cells

The pathogenic agent, adenovirus (Ad), has taken on a new role as a vector for gene transfer in both laboratory and clinical settings. To help understand the intracellular pathways and fate of Ad gene transfer vectors, we covalently conjugated fluorophores to E1-, E3- Ad vectors and used quantitative fluorescence microscopy to assess essential steps of Ad vector gene transfer to the A549 human epithelial lung cell line including binding, internalization, escape from endosomes, translocation to the nucleus, dissociation of capsids and gene expression. The data demonstrate that Ad internalizes with a t1/2 2.5 min, breaks out of endosomes early, likely prior to endosome-endosome fusion, exhibits sustained, intracellular velocities averaging 0.58 microm/sec, and translocates to the nucleus with >80% of internalized fluorophore demonstrating nuclear localization within 60 min of infection. Interestingly, 24 hr after infection, half of the initially internalized fluorescence was detected but lacked nuclear localization, suggesting that the capsid is released from the nucleus and is likely degraded. Fluorescent labeling of virions provides a novel quantitative, morphological strategy to characterize the interaction of gene transfer vectors with the intracellular environment.

Spontaneous echocardiographic contrast in the descending thoracic aorta

Spontaneous echocardiographic contrast (SEC) is an occasional finding observed in the atria in patients undergoing transesophageal echocardiographic studies, but has rarely been described in the descending thoracic aorta in the absence of an aortic dissection. The pathophysiology of SEC in the cardiac and vascular structures appears to be related to an interaction between red blood cells and plasma proteins in the setting of a low flow state. In this report we present three cases of SEC in the descending thoracic aorta, with one of the cases of SEC resolving with repair of his underlying cardiac disorder.