Nanoparticulate systems for brain delivery of drugs

Effects of nanoparticles on the adhesion and cell viability on astrocytes

In recent years, both pharmaceutical companies and manufacturing industries have expressed heightened interest in the potential applications of magnetic nanoparticles for therapeutic and technological purposes. Specifically, pharmaceutical companies seek to employ magnetic nanoparticles as carriers to facilitate effective drug delivery, especially in areas of the brain. Manufacturing industries desire to use these nanoparticles as ferrofluids and in magnetic resonance imaging. However, data concerning the effects of magnetic nanoparticles on the nervous system is limited. This study tested the hypotheses that nanoparticles can (1) inhibit adherence of astrocytes to culture plates and (2) cause cytotoxicity or termination of growth, both end points representing surrogate markers of neurotoxicity. Using light microscopy, changes in plating patterns were determined by visual assessment. Cell counting 4 days after plating revealed a significant decrease in the number of viable astrocytes in nanoparticle treated groups (p < 0.0001). To determine the cytotoxic effects of nanoparticles, astrocytes were allowed to adhere to culture plates and grow to maturity for 3 weeks before treatment. Membrane integrity and mitochondrial function were measured using colorimetric analysis lactate dehydrogenase (LDH) and 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTS), respectively. Treatment with nanoparticles did not significantly alter astrocytic LDH release (p > 0.05) in the control group (100% +/- 1.56) vs the group receiving treatment (97.18% +/- 2.03). However, a significant increase in MTS activity (p < 0.05) between the control (100% +/- 3.65) and treated groups (112.8% +/- 3.23) was observed, suggesting astrocytic mitochondrial uncoupling by nanoparticles. These data suggest that nanoparticles impede the attachment of astrocytes to the substratum. However, once astrocytes attach to the substratum and grow to confluence, nanoparticles may cause mitochondrial stress.

Apolipoprotein A-I coating of protamine-oligonucleotide nanoparticles increases particle uptake and transcytosis in an in vitro model of the blood-brain barrier

Drug delivery to the brain is severely restricted by formation of tight junctions between adjacent brain capillary endothelial cells (BCEC). In the present study we have evaluated the effects of protamine-oligonucleotide nanoparticles (proticles) on the functional properties of primary porcine BCEC and characterized uptake and transcytosis of proticles by these cells. Proticles had no adverse effects on BCEC properties relevant to blood-brain barrier (BBB) function. Transcytosis of (125)I-labeled proticles across polarized BCEC cultures occurred in a time- and concentration-dependent manner. As apolipoproteins were suggested to enhance cellular proticle uptake, proticle coating was performed with apoA-I, the major apolipoprotein component of high density lipoproteins. Adsorption of apoA-I on the surface of proticles resulted in significantly improved uptake and transcytosis properties as compared to uncoated proticles. ApoA-I coating enhanced proticle delivery to astrocytes in an in vitro model of the BBB almost twofold. Blocking of scavenger receptor class B, type I (the prime receptor for high density lipoprotein/apoA-I that is expressed on BCEC) reduced transcytosis of apoA-I-coated proticles to levels observed for uncoated proticles. Our data indicate that apoA-I-coating of proticles could be a feasible targeting technology to improve delivery across the BBB.

Core-shell type of nanoparticles composed of poly[(n-butyl cyanoacrylate)-co-(2-octyl cyanoacrylate)] copolymers for drug delivery application: Synthesis, characterization and in vitro degradation

Core-shell type of nanoparticles (NPs) with manipulated degradation rate and balanced hydrophilic/hydrophobic properties were designed and characterized. The NPs based on the copolymers of n-butyl cyanoacrylate (BCA) and 2-octyl cyanoacrylate (OCA) were prepared by anion emulsion polymerization in 0.01N HCl solution with pluronic F127 as the stabilizer. These NPs were spherical in shape and with size smaller than 100 nm in a narrow distribution. The particle size, zeta potential, molecular weight, hydrophobicity and degradation rate of the copolymer depended on its composition significantly. In vitro chemical hydrolytic studies indicated that the degradation rate of the NPs could be controlled over 200-fold by adjusting the BCA/OCA ratio. Differential scanning calorimetry (DSC) measurements verified the existence of copolymer with tapered structure which was induced by the reactivity difference of the monomers. A BCA/OCA core-shell structure is postulated that the OCA rich segments were mainly located in the core of the NPs. The cytotoxicity of poly(2-octyl cyanoactylate) (POCA) is quite lower than that of poly(n-butyl cyanoacrylate) (PBCA) and the toxicity of poly(BCA-co-OCA) NPs is similar to that of PBCA NPs.

Blood-brain barrier and chemotherapeutic treatment of brain tumors

The blood-brain barrier (BBB) is of pivotal importance to maintain homeostasis of the CNS, as it closely regulates the composition of the interstitial fluid in the brain. Unfortunately, malignancies that grow within the CNS may evade chemotherapeutic drugs using the same barrier, making this disease refractory to most chemotherapy regimens. This review will outline the impact of the BBB in brain cancer and discuss the efforts that have been made to enhance the drug exposure of brain tumors. Although this review will focus on the role of the BBB in primary brain cancer (malignant glioma), its impact on brain metastases will also be briefly discussed.

Nanoparticle iron chelators: a new therapeutic approach in Alzheimer disease and other neurologic disorders associated with trace metal imbalance

Accumulating evidence suggests that oxidative stress may be a major etiologic factor in initiating and promoting neurodegeneration in Alzheimer disease. Contributing to this, there is a dyshomeostasis of metal ions in Alzheimer disease with abnormally high levels of redox-active metals, particularly iron, in affected areas of the brain. Although it is unclear whether metal excesses are the sole cause of oxidative stress and neurodegeneration or a by-product of neuronal loss, the finding that metal chelators can partially solubilize amyloid-beta deposits in Alzheimer disease suggests a promising therapeutic role for chelating agents. However, the blood-brain barrier and toxicity of known chelators limit their utility. In this study, we suggest that covalent conjugation of iron chelators with nanoparticles may help overcome the limitations in blood-brain barrier permeability of existing chelation therapy. Using in vitro studies, we have shown that a chelator-nanoparticle system and the chelator-nanoparticle system complexed with iron, when incubated with human plasma, preferentially adsorb apolipoprotein E and apolipoprotein A-I, that would facilitate transport into and out of the brain via mechanisms used for transporting low-density lipoprotein. Our studies suggest a unique approach, utilizing nanoparticles, to transport chelators and chelator-metal complexes in both directions across the blood-brain barrier, thus providing safer and more effective chelation treatment in Alzheimer disease and other neurodegenerative diseases.

The pharmacology of particulate matter air pollution-induced cardiovascular dysfunction

Since the London fog of 1952, in which more than 4000 people were killed in 4 days, the combined efforts of scientists from several disciplines, including those from the environmental health, clinical and biomedical disciplines, have raised serious concerns about the impact of air pollutants on human health. These environmental pollutants are rapidly being recognized as important and independent risk factors for several diseases such as asthma, chronic obstructive pulmonary disease, lung cancer, atherosclerosis, ischemic heart disease and stroke. Although the relative effects of particulate matter air pollution (aerodynamic diameter <10 microm, or PM(10)) are greater for respiratory than for cardiovascular deaths, the number of deaths attributable to PM(10) is much larger for cardiovascular than for respiratory reasons due to the higher prevalence of cardiovascular disease in the general population. This review summarizes current understanding of the mechanisms underlying the associations between PM(10) exposure and cardiovascular morbidity and mortality.

An attempt to directly trace polymeric nanoparticles in vivo with electron microscopy

This work attempted to directly observe polymeric nanoparticles in vivo by analytical electron microscopy (AEM) using copper chlorophyll as the contrast agent, based on the experiments concerned with the copper chlorophyll labeled poly-DL-lactide nanoparticles and the in vivo distribution of the polysorbate 80 (T-80)-coated nanoparticles in brain tissues. With the nanoprecipitation method without surfactants, copper chlorophyll is aggregated in the coordinately saturated form and encapsulated by the matrices of nanoparticles, which may ensure the stability of copper chlorophyll during the in vivo experiments. From both morphological information and chemical information, only the labeled nanoparticles with the T-80 coating were directly traced in the brain by AEM. The results not only support the mechanism of endocytosis and/or transcytosis of T-80-coated nanoparticles targeted to the brain but also verify that it is practical to probe polymeric nanoparticles in vivo using AEM together with copper chlorophyll as the contrast agent.

Parameters influencing the stealthiness of colloidal drug delivery systems

Over the last few decades, colloidal drug delivery systems (CDDS) such as nano-structures have been developed in order to improve the efficiency and the specificity of drug action. Their small size permits them to be injected intravenously in order to reach target tissues. However, it is known that they can be rapidly removed from blood circulation by the immune system. CDDS are removed via the complement system and via the cells of the mononuclear phagocyte system (MPS), after their recognition by opsonins and/or receptors present at the cell surface. This recognition is dependent on the physicochemical characteristics of the CDDS. In this study, we will focus on parameters influencing the interactions of opsonins and the macrophage plasma membrane with the surface of CDDS, whereby parameters of the polymer coating become necessary to provide good protection.

Effect of nanoparticulate polybutylcyanoacrylate and methylmethacrylate-sulfopropylmethacrylate on the permeability of zidovudine and lamivudine across the in vitro blood-brain barrier

Effect of size of nanoscaled polybutylcyanoacrylate (PBCA) and methylmethacrylate-sulfopropylmethacrylate (MMA-SPM) on the permeability of zidovudine (AZT) and lamivudine (3TC) across the blood-brain barrier (BBB) was investigated. Also, influence of alcohol on the permeability of AZT and 3TC incorporated with the two polymeric nanoparticles (NPs) was examined. The loading efficiency and the permeability of AZT and 3TC decreased with an increase in the particle size of the two carriers. By employing PBCA NPs, the BBB permeability of AZT and that of 3TC became, respectively, 8-20 and 10-18 folds. Application of MMA-SPM NPs leaded to about 100% increase in the BBB permeability of the two drugs. In the presence of 0.5% ethanol, 4-12% enhancement in the BBB permeability of the two drugs was obtained in the current carrier-mediated system.

Synergistic enhancement effect of magnetic nanoparticles on anticancer drug accumulation in cancer cells

Three kinds of magnetic nanoparticle, tetraheptylammonium capped nanoparticles of Fe(3)O(4), Fe(2)O(3) and Ni have been synthesized, and the synergistic effect of these nanoparticles on the drug accumulation of the anticancer drug daunorubicin in leukaemia cells has been explored. Our observations indicate that the enhancement effect of Fe(3)O(4) nanoparticles is much stronger than that of Fe(2)O(3) and Ni nanoparticles, suggesting that nanoparticle surface chemistry and size as well as the unique properties of the magnetic nanoparticles themselves may contribute to the synergistic enhanced effect of the drug uptake of targeted cancer cells.

Biodistribution of polysorbate 80-coated doxorubicin-loaded [14C]-poly(butyl cyanoacrylate) nanoparticles after intravenous administration to glioblastoma-bearing rats

It was recently shown that doxorubicin (DOX) bound to polysorbate-coated nanoparticles (NP) crossed the intact blood-brain barrier (BBB), and thus reached therapeutic concentrations in the brain. Here, we investigated the biodistribution in the brain and in the body of poly(butyl-2-cyano[3-(14)C]acrylate) NP ([(14)C]-PBCA NP), polysorbate 80 (PS 80)-coated [(14)C]-PBCA NP, DOX-loaded [(14)C]-PBCA NP in glioblastoma 101/8-bearing rats after i.v. injection. The biodistribution profiles and brain concentrations of radiolabeled NP were determined by radioactivity counting after i.v. administration in rats. Changes in BBB permeability after tumour inoculation were assessed by i.v. injection of Evans Blue solution. The accumulation of NP in the tumour site and in the contralateral hemisphere in glioblastoma bearing-rats probably was augmented by the enhanced permeability and retention effect (EPR effect) that may have been becoming instrumental due to the impaired BBB on the NP delivery into the brain. The uptake of the NP by the organs of the reticuloendothelial system (RES) was reduced after PS 80-coating, but the addition of DOX increased again the concentration of NP in the RES.

A new generation of anticancer, drug-loaded, colloidal vectors reverses multidrug resistance in glioma and reduces tumor progression in rats

By focusing on rat glioma, we elucidated whether new lipid nanocapsules (LNC) were able to improve anticancer hydrophobic drug bioavailability while also overcoming multidrug resistance. Blank LNCs and LNCs loaded with the antineoplastic agent paclitaxel were formulated by an emulsion inversion phase process. Expression of efflux pumps by rat glioma cells was assessed by reverse transcription-PCR, Western blot, and immunohistochemistry, and their activity was followed using the tracer (99)Tc(m)-methoxyisobutylisonitrile. Modalities of LNC action were addressed by using confocal microscopy detection of fluorescently labeled LNCs, fluorescence-activated cell sorting, high-performance liquid chromatography measurement of paclitaxel release, and analysis of tumor cell growth. This revealed an interaction between LNCs and efflux pumps that resulted in an inhibition of multidrug resistance in glioma cells, both in culture and in cell implants in animals. LNCs were able to target the intracellular compartment of glioma cells, a mechanism that was abrogated by using intracellular cholesterol inhibitors but not by clathrin-coated pit or caveolae uptake inhibitors. This result can be correlated to the LNC inhibitory effects on efflux pump activity that is itself known to be stimulated by intracellular cholesterol. In parallel, we showed that paclitaxel-loaded LNCs were active reservoirs from which paclitaxel could be released. Finally, we established that paclitaxel-loaded LNCs were more efficient than the commercially available paclitaxel formulation (Taxol) for clinical use, thus reducing tumor expansion in vitro and in vivo. Considering the physiologically compatible nature of LNC excipients, these data may represent an important step towards the development of new clinical therapeutic strategies against cancers.

Electrohydrodynamic atomization for biodegradable polymeric particle production

Electrohydrodynamic atomization (EHDA) has many applications such as electrospray ionization in mass spectroscopy, electrospray deposition of thin films, pharmaceutical productions, and polymeric particle fabrications for drug encapsulation. In the present study, EHDA was employed to produce biodegradable polymeric micro- and nanoparticles. The effects of processing parameters such as polymer concentration, flow rate, surfactants, organic salt, and setup configurations on the size and morphology of polymeric particles were investigated systematically. By changing the various processing parameters, controllable particle shape and size can be achieved. PLGA nanoparticles with size of around 250 nm can be obtained by using organic salts to increase the conductivity of the spraying solution even at a relatively high flow rate. A higher flow rate has the advantage of producing a stable cone spray and can be easily reproduced. Solid and porous particles can be fabricated using different experimental setups to control the organic solvent evaporation rate. Also, paclitaxel, a model antineoplastic drug, was encapsulated in polymeric particles which can be employed for controlled release applications. In short, EHDA is a promising technique to fabricate polymeric micro- or nanoparticles which can be used in drug delivery systems.

Nanoencapsulation II. Biomedical applications and current status of peptide and protein nanoparticulate delivery systems

The concept of polymeric nanoparticles for the design of new drug delivery systems emerged a few years ago, and recent rapid advances in nanotechnology have offered a wealth of new opportunities for diagnosis and therapy of various diseases. Recent progress has made possible the engineering of nanoparticles to allow the site-specific delivery of drugs and to improve the pharmacokinetic profile of numerous compounds with biomedical applications such as peptide and protein drugs. Biologically active peptides and their analogues are becoming an increasingly important class of drugs. Their use for human and animal treatment is problematic, however, because some of these drugs are generally ineffective when taken orally and thus have been administered chiefly by the parenteral route. This review covers some of the historical and recent advances of nanotechnology and concludes that polymeric nanoparticles show great promise as a tool for the development of peptide drug delivery systems.

Cytotoxicity of water-soluble fullerene in vascular endothelial cells

Nanoscale materials are presently under development for diagnostic (nanomedicine) and electronic purposes. In contrast to the potential benefits of nanotechnology, the effects of nanomaterials on human health are poorly understood. Nanomaterials are known to translocate into the circulation and could thus directly affect vascular endothelial cells (ECs), causing vascular injury that might be responsible for the development of atherosclerosis. To explore the direct effects of nanomaterials on endothelial toxicity, human umbilical vein ECs were treated with 1–100 μg/ml hydroxyl fullerene [C60(OH)24; mean diameter, 7.1 ± 2.4 nm] for 24 h. C60(OH)24 induced cytotoxic morphological changes such as cytosolic vacuole formation and decreased cell density in a dose-dependent manner. Lactate dehydrogenase assay revealed that a maximal dose of C60(OH)24 (100 μg/ml) induced cytotoxic injury. Proliferation assay also showed that a maximal dose of C60(OH)24 inhibited EC growth. C60(OH)24 did not seem to induce apoptosis but caused the accumulation of polyubiquitinated proteins and facilitated autophagic cell death. Formation of autophagosomes was confirmed on the basis of Western blot analysis using a specific marker, light chain 3 antibody, and electron microscopy. Chronic treatment with low-dose C60(OH)24 (10 μg/ml for 8 days) inhibited cell attachment and delayed EC growth. In the present study, we have examined, for the first time, the toxicity of water-soluble fullerenes to ECs. Although fullerenes changed morphology in a dose-dependent manner, only maximal doses of fullerenes caused cytotoxic injury and/or death and inhibited cell growth. EC death seemed to be caused by activation of ubiquitin-autophagy cell death pathways. Although exposure to nanomaterials appears to represent a risk for cardiovascular disorders, further in vivo validations are necessary.

Toward the Emergence of Nanoneurosurgery: Part III—Nanomedicine: Targeted Nanotherapy, Nanosurgery, and Progress Toward the Realization of Nanoneurosurgery

The notion of nanotechnology has evolved since its inception as a fantastic conceptual idea to its current position as a mainstream research initiative with broad applications among all divisions of science. In the first part of this series, we reviewed the structures and principles that comprise the main body of knowledge of nanoscience and nanotechnology. In the second part, we discussed applications of nanotechnology to the emerging field of nanomedicine, with specific attention on medical diagnostics and imaging. This article further explores the applications of nanotechnology to nanomedicine. Specific attention is given to developments in therapeutic modalities, including advanced drug delivery systems and targeted nanotherapy, which will form the basis for the treatment arm of mature nanomedicine. A variety of modalities are discussed, including polymeric nanoparticles, micelles, liposomes, dendrimers, fullerenes, hydrogels, nanoshells, and smart surfaces. Applications of nanotechnology to nanosurgery and nanoneurosurgery are presented. Femtosecond laser systems, nanoneedles, and nanotweezers are presented as technologies that are operational at the nanoscale level and have the potential to revolutionize the practice of neurosurgery in a profound and momentous way.

Polylactic acid nanoparticles targeted to brain microvascular endothelial cells

In this work, blank polylactic acid (PLA) nanoparticles with unstained surface were prepared by the nano-deposition method. On the basis of the preparation, the effect of surface modification on brain microvascular endothelial cells (BMECs) targeting was examined by in vivo experiments and fluorescence microscopy. The results showed that PLA nanoparticles are less toxic than PACA nanoparticles but their BMECs targeting is similar to PACA nanoparticles. The experiments suggest that drugs can be loaded onto the particles and become more stable through adsorption on the surface of PLA nanoparticles with high surface activity. The surface of PLA nanoparticles was obviously modified and the hydrophilicity was increased as well in the presence of non-ionic surfactants on PLA nanoparticles. As a targeting moiety, polysobate 80 (T-80) can facilitate BMECs targeting of PLA nanoparticles.

Role of antioxidants in prophylaxis and therapy: A pharmaceutical perspective

Antioxidants are emerging as prophylactic and therapeutic agents. These are the agents, which scavenge free radicals otherwise reactive oxygen species and prevent the damage caused by them. Free radicals have been associated with pathogenesis of various disorders like cancer, diabetes, cardiovascular diseases, autoimmune diseases, neurodegenerative disorders and are implicated in aging. Several antioxidants like SOD, CAT, epigallocatechin-3-O-gallate, lycopene, ellagic acid, coenzyme Q10, indole-3-carbinol, genistein, quercetin, vitamin C and vitamin E have been found to be pharmacologically active as prophylactic and therapeutic agents for above mentioned diseases. Antioxidants are part of diet but their bioavailability through dietary supplementation depends on several factors. This major drawback of dietary agents may be due to one or many of the several factors like poor solubility, inefficient permeability, instability due to storage of food, first pass effect and GI degradation. Conventional dosage forms may not result in efficient formulation owing to their poor biopharmaceutical properties. Principles of novel drug delivery systems need to be applied to significantly improve the performance of antioxidants. Novel drug delivery systems (NDDS) would also help in delivery of these antioxidants by oral route, as this route is of prime importance when antioxidants are intended for prophylactic purpose. Implication of NDDS for the delivery of antioxidants is largely governed by physicochemical characteristics, biopharmaceutical properties and pharmacokinetic parameters of the antioxidant to be formulated. Recently, chemical modifications, coupling agents, liposomes, microparticles, nanoparticles and gel-based systems have been explored for the delivery of these difficult to deliver molecules. Results from several studies conducted across the globe are positive and provided us with new anticipation for the improvement of human healthcare.

Nanoparticle-based in vivo investigation on blood-brain barrier permeability following ischemia and reperfusion

The blood-brain barrier (BBB) represents a significant impediment to a large variety of central nervous system-active agents. In the current study, we applied fluorescent polystyrene nanospheres (20 nm) to study the BBB permeability following cerebral ischemia and reperfusion. A microdialysis probe was implanted in the cerebral cortex of an anesthetized rat injected with fluorescent polystyrene nanospheres. The circulating nanospheres extravasating to the brain extracellular fluids were collected by the probe. Fluorescence intensity in the microdialysates throughout the course of cerebral ischemia/reperfusion was measured. Cerebral ischemia and reperfusion induced transient accumulations of extracellular nanospheres in the brain. The accumulation of nanospheres may result from their extravasation from the blood vessels. The concurrent cerebral oxygen levels monitored using oxygen-dependent quenching of phosphorescence decreased following ischemia and returned to their original levels after reperfusion. In conclusion, we demonstrated that high temporal resolution measurements of BBB permeability in vivo can be obtained using fluorescence polystyrene nanospheres and that these data correlate with changes of cerebral oxygen concentration. This present investigation indicates that nanoparticles have potential clinical applications involving drug delivery and determination of therapeutic efficacy and on-site diagnosis.

Cationic liposomes modified with non-ionic surfactants as effective non-viral carrier for gene transfer

A defined change in formulation components affects the physical and chemical characteristics of cationic liposomes (CLs) carriers in many ways. Therefore, a great degree of control can be exercised over the structure by modifying the CLs with various materials, leading to new innovations for carrier improvement. In the present study, surface modifications of cationic liposomes with non-ionic surfactants--sorbitan monoesters serials (Span 85, 80, 40 and 20) were carried out for developing a new gene transfer carrier. Span modified cationic liposomes (Sp-CLs) were prepared by reverse phase evaporation method (RPV) and self-assemble complexes of antisense oligonucleotides/surfactant modifying cationic liposomes were prepared by auto-coacervation through electrostatic effect. Characterization of Sp-CLs and the self-assembled complex was performed by electron microscope, particle size, zeta potential, turbidity and agarose electrophoresis. Furthermore, in vitro cellular uptake experiment showed that Span plays a role in enhancing the cellular uptake of encapsulated oligonucleotides mediated by Sp-CLs by the endocytosis-dependent route. CLs modified with Span 40 significantly facilitated the cellular uptake by COS-7 cells and HeLa cells; also showed some positive effect on gene expression. That suggests it is a potential non-viral carrier for efficient gene transfer.

Drug delivery across the blood–brain barrier: why is it difficult? how to measure and improve it?

The development of drugs that act in the CNS has been significantly impeded by the difficulty of delivering them across the blood-brain barrier (BBB). This article aims to provide the reader with a critical overview of important issues in the discovery and development of drugs that need to enter the brain to elicit pharmacological activity, focusing particularly on i) the role of drug transporters in brain permeation and how to manipulate them to enhance drug brain bioavailability; ii) the successful application, limitations and challenges of commonly used in vitro and in vivo methodologies for measuring drug transport across the BBB, and iii) a discussion of recently developed strategies (e.g., modulation of efflux transporters by chemical inhibitors and the employment of delivery vectors taking advantage of native transport systems at the BBB) for facilitating drug penetration into the brain.

In-vivo efficacy of novel paclitaxel nanoparticles in paclitaxel-resistant human colorectal tumors

Colloidal carriers have been shown to improve tumor therapy by increased drug delivery into tumor sites resulting directly from the enhanced permeability and retention effect (EPR). However, the clinical outcome of tumor therapy is often limited due to multidrug resistance. Several different types of resistance exist with expression of p-glycoprotein being the most commonly described. Paclitaxel entrapped in emulsifying wax nanoparticles (PX NPs) was shown to overcome drug resistance in a human colon adenocarcinoma cell line (HCT-15). In the present studies, the in-vivo efficacy of PX NPs in a HCT-15 mouse xenograft model was demonstrated. Significant inhibition in tumor growth was observed in mice receiving PX NPs treatment. Additionally, mice dosed with Taxol also demonstrated slower tumor growth; however, the efficacy of the Taxol treatment was shown in the in-vitro HUVEC model to be due to the antiangiogenic effect of paclitaxel. It was concluded that the enhanced efficacy of PX NPs over Taxol in the xenograft model was due to both overcoming paclitaxel resistance and an antiangiogenic effect.

Preoperative endovascular brain mapping for intraoperative volumetric image guidance: preliminary concept and feasibility in animal models

Object

The authors describe a novel concept for brain mapping in which an endovascular approach is used, and they demonstrate its feasibility in animal models. The purpose of endovascular brain mapping is to delineate clearly the nonfunctional brain parenchyma when a craniotomy is performed for resection. The nonfunctional brain will be stained with sharp visual margins, differentiating it from the functional, nonstained brain. The authors list four essential criteria for developing an ideal endovascular mapping agent, and they describe seven potential approaches for accomplishing a successful endovascular brain map.

Methods

Four Sprague–Dawley rats and one New Zealand white rabbit were used to determine initial feasibility of the procedure. The animals were anesthetized, and the internal carotid artery was catheterized. Four potential brain mapping agents were infused into the right hemisphere of the five animals. Afterward, the brains were removed and each was analyzed both grossly and histologically.

Fluorescein and FD&C Green No. 3 provided good visual clarity and margins, but required blood–brain barrier (BBB) manipulation. Tantalum particles enabled avoidance of BBB manipulation, but provided inadequate visual clarity, probably because of their size. A Sudan black “cocktail” provided excellent clarity and margins despite remaining in the brain capillaries.

Conclusions

This is a novel application of the endovascular approach, and has broad potential for clinical neurosurgical brain mapping. The animal models in this study establish the feasibility of the procedure. However, further study is required to demonstrate safety, minimize toxicity, investigate stain durability, and improve the characteristics of potential mapping agents. The authors are planning to conduct future studies for identification of mapping agents that do not require BBB manipulation or vascular occlusion.

In Vitro Investigation on Poly(lactide)−Tween 80 Copolymer Nanoparticles Fabricated by Dialysis Method for Chemotherapy

Polysorbate 80 (Tween 80) has been widely used as an emulsifier with excellent effects in nanoparticles technology for biomedical applications. This work was thus triggered to synthesize poly(lactide)/Tween 80 copolymers with various copolymer blend ratio, which were synthesized by ring-opening polymerization and characterized by 1H NMR and TGA. Nanoparticles of poly(lactide)/Tween 80 copolymers were prepared by the dialysis method without surfactants/emulsifiers involved. Paclitaxel was chosen as a prototype anticancer drug due to its excellent therapeutic effects against a wide spectrum of cancers. The drug-loaded nanoparticles of poly(lactide)/Tween 80 copolymers were then characterized by various state-of-the-art techniques, including laser light scattering for particles size and size distribution, field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) for surface morphology; laser Doppler anemometry for zeta potential; differential scanning calorimetry (DSC) for the physical status of the drug encapsulated in the polymeric matrix; X-ray photoelectron spectrometer (XPS) for surface chemistry; high performance liquid chromatography (HPLC) for drug encapsulation efficiency; and in vitro drug release kinetics. HT-29 cells and Glioma C6 cells were used as an in vitro model of the GI barrier for oral chemotherapy and a brain cancer model to evaluate in vitro cytotoxicity of the paclitaxel-loaded nanoparticles. The viability of C6 cells was decreased from 37.4 +/- 4.0% for poly(D,L-lactide-co-glycolic acid) (PLGA) nanoparticles to 17.8 +/- 4.2% for PLA-Tween 80-10 and 12.0 +/- 5.4% for PLA-Tween 80-20 copolymer nanoparticles, which was comparable with that for Taxol at the same 50 microg/mL drug concentration.

Neuroscience nanotechnology: progress, opportunities and challenges

Nanotechnologies exploit materials and devices with a functional organization that has been engineered at the nanometre scale. The application of nanotechnology in cell biology and physiology enables targeted interactions at a fundamental molecular level. In neuroscience, this entails specific interactions with neurons and glial cells. Examples of current research include technologies that are designed to better interact with neural cells, advanced molecular imaging technologies, materials and hybrid molecules used in neural regeneration, neuroprotection, and targeted delivery of drugs and small molecules across the blood-brain barrier.

Preparation and properties of poly(vinyl alcohol)-stabilized liposomes

The purpose of this work is to evaluate the improvement in physical stability of poly(vinyl alcohol) (PVA) modified liposomes. Liposomes composed of soya phosphatidylcholile (SPC) and cholesterol (1:1 molar ratio) were prepared by reverse phase evaporation method. Two types of interaction between liposome and PVA were investigated: PVA addition into lipid bilayer during liposome preparation and coating of already formed liposomes with PVA. The microparticles system was morphologically characterized by transmission electron microscopy (TEM) and particles analysis. Changes in particles size and zeta potential confirmed the existence of a thick polymer layer on the surface of liposomes. The amount of PVA adsorbing to liposomes and the encapsulation efficiency increased with increasing polymer concentration. The physical stability was evaluated by measuring the release rate of contents at 20 and 37 degrees C, the PVA modified liposomes were more stable than the conventional liposomes. Comparing with PVA-coated liposomes, the liposomes with PVA addition to the bilayer were more stable, and had higher entrapment efficiency.

CNS drug delivery: opioid peptides and the blood-brain barrier

Peptides are key regulators in cellular and intercellular physiological responses and possess enormous promise for the treatment of pathological conditions. Opioid peptide activity within the central nervous system (CNS) is of particular interest for the treatment of pain owing to the elevated potency of peptides and the centrally mediated actions of pain processes. Despite this potential, peptides have seen limited use as clinically viable drugs for the treatment of pain. Reasons for the limited use are primarily based in the physiochemical and biochemical nature of peptides. Numerous approaches have been devised in an attempt to improve peptide drug delivery to the brain, with variable results. This review describes different approaches to peptide design/modification and provides examples of the value of these strategies to CNS delivery of peptide drugs. The various modes of modification of therapeutic peptides may be amalgamated, creating more efficacious "hybrid" peptides, with synergistic delivery to the CNS. The ongoing development of these strategies provides promise that peptide drugs may be useful for the treatment of pain and other neurologically-based disease states in the future.

Pharmacokinetics and tissue distribution of etoposide delivered in long circulating parenteral emulsion

PURPOSE

The aim of the study is to ascertain the influence of pegylation of parenteral emulsion (PE) on their long circulating property.

METHODS

Etoposide encapsulated parenteral emulsion (EPE) was prepared using soybean oil, egg lecithin and cholesterol. Etoposide encapsulated long circulating parenteral emulsion (PEG-EPE) was prepared using PEG (2000)-DSPE as a stealth agent. The effect of monovalent and divalent electrolytes on the stability of EP was assessed by measuring the fixed aqueous layer thickness (FALT) and flocculation rate. Pharmacokinetics and tissue distribution pattern of PE following i.v. (bolus) were assessed in Wistar rats and Swiss albino mice.

RESULTS

FALT of PEG-EPE was larger than that of EPE. In case of PEG-EPE, as the concentration of pegylated lipid (PEG) increased from 0.15 to 0.45% w/v the flocculation rate decreased asymptomatically in the presence of monovalent and divalent electrolytes. The increased circulation time of PEG-EPE (0.3%) after intravenous injection to rats confirms the presence of FALT around globules. PEG-EPE showed improved pharmacokinetic parameters with 5.5 times higher AUC than etoposide commercial formulation (ETP). Tissue distribution results show that etoposide levels in all tissues except in brain and heart were lower in case of PEG-EPE than ETP. The percentage of tumor growth suppression rate (%T/C) in Lewis lung carcinoma bearing mice was 63.23, 62.83 and 33.78% in EPE, PEG-EPE and ETP treated mice, respectively. The improved activity of PEG-EPE is due to enhanced permeability and retention effect (EPR).

CONCLUSION

Encapsulation of etoposide in PEG-coated PE produced improved pharmacokinetic profile than that of EPE and ETP.

Influence of particle size on transport of methotrexate across blood brain barrier by polysorbate 80-coated polybutylcyanoacrylate nanoparticles

Transports of methotrexate-loaded polybutylcyanoacrylate nanoparticles with different sizes across blood brain barrier were investigated in this experiment. The drug-loaded nanoparticles were prepared by emulsion polymerization method. After coating with polysorbate 80, nanoparticles with the size 70, 170, 220, 345 nm were, respectively, i.v. injected into rats at the dose of 3.2 mg/kg. Uncoated nanoparticles and methotrexate solution were also i.v. injected at the same dosage as controls. 0.5, 1, 1.5, 2, 3, 4 h after injection, cerebrospinal fluids and brain tissues were collected for tests. Drug level in all biological samples was determined by HPLC. It was found out that nanoparticles overcoated by polysorbate 80 could significantly improve the drug level in both brain tissues and cerebrospinal fluids compared with uncoated ones and simple solution. Seventy-nanometer nanoparticles could deliver more drugs into brain while no significant difference was observed among the other three size ranges. In conclusion, polysorbate 80-coated polybutylcyanoacrylate nanoparticles could be used to overcome blood brain barrier especially those whose diameter was below 100 nm.

Nanocarriers: Promising Vehicle for Bioactive Drugs

Development of new delivery systems that deliver the potential drug specifically to the target site in order to meet the therapeutic needs of the patients at the required time and level remains the key challenge in the field of pharmaceutical biotechnology. Developments in this context to achieve desired goal has led to the evolution of the multidisciplinary field nanobiotechnology which involves the combination of two most promising technologies of 21st century--biotechnology and nanotechnology. Nanobiotechnology encompasses a wide array of different techniques to improve the delivery of biotech drugs, and nanoparticles offer the most suitable form whose properties can be tailored by chemical methods. This review highlights the different types of nanoparticulate delivery systems employed for biotech drugs in the field of molecular medicine with a short overlook at its applications and the probable associated drawbacks.

Nanotechnology and Nanotoxicology

Nanotechnology is the manipulation of matter in dimensions <100 nm. At this size, matter can take on different chemical and physical properties, giving the products characteristics useful to industry, medicine and technology. Government funding and private investors provide billions of research dollars for the development of new materials and applications. The potential utility of these technologies is such that they are expected be a trillion-dollar industry within the next 10 years. However, the novel properties of nanoengineered materials lead to the potential for different toxicity compared with the bulk material. The field of nanotoxicology is still in its infancy, however, with very limited literature regarding potential health effects. Inhalational toxicity is to be expected, given the known effects of inhaled fine particulate matter. However, the degree to which most nanoparticles will aerosolise remains to be determined. It has been proposed that dermal exposure will be the most relevant route of exposure, but there is considerably less literature regarding dermal effects and absorption. Less defined still are the potential effects of nanoproducts on fetal development and the environment.

Thioflavins released from nanoparticles target fibrillar amyloid β in the hippocampus of APP/PS1 transgenic mice

For the delivery of drugs into the brain, the use of nanoparticles as carriers has been described as a promising approach. Here, we prepared nanoparticles as carriers for the model drugs thioflavin T and thioflavin S that bind fibrillar amyloid beta peptides (Abeta). These polymer colloids are composed of a polystyrene core and a degradable PBCA [poly(butyl-2-cyanoacrylate)] shell with a diameter of 90-100nm as shown by dynamic light scattering. Fluorescence spectrophotometric analysis revealed that encapsulated thioflavin T exhibited significantly stronger fluorescence than the free fluorophore. The enzymatic degradation of core-shell nanoparticles, as required in vivo, was shown after their treatment with porcine liver esterase, a non-specific esterase, in vitro. Shells of nanoparticles were dose-dependently degraded while their polystyrene cores remained intact. In the cortices of 7-14 months old APP/PS1 mice with age-dependent beta-amyloidosis, thioflavins selectively targeted fibrillar Abeta after biodegradation-induced release from their nanoparticulate carriers upon intracerebral injection. Collectively, our data suggest that core-shell nanoparticles with controlled degradation in vivo can become versatile tools to trace and clear Abeta in the brain.

Novel functionalized biodegradable polymers for nanoparticle drug delivery systems

We have prepared and screened a library of novel functionalized polymers for development of nanoparticle drug delivery systems. The polymer backbone consisting of two ester-linked, nontoxic, biological monomers, glycerol and adipic acid, was prepared using a hydrolytic enzyme. The specificity of the chosen enzyme yields a linear polymer with one free pendant hydroxyl group per repeat unit, which can be further functionalized. This protocol gives control over the backbone polymer molecular weight, together with the ability to incorporate various amounts of different fatty acyl substituents. These functionalized polymers are able to self-assemble into well-defined small particles of high homogeneity with a very low toxicity. They are able to incorporate a water soluble drug, dexamethasone phosphate, with a high efficiency and drug loading which varies with the polymer specification. The above characteristics strongly suggest that these polymers could be developed into useful nanoparticulate drug delivery systems.

Targeted nanoparticles for drug delivery through the blood–brain barrier for Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia among the elderly, affecting 5% of Americans over age 65, and 20% over age 80. An excess of senile plaques (beta-amyloid protein) and neurofibrillary tangles (tau protein), ventricular enlargement, and cortical atrophy characterizes it. Unfortunately, targeted drug delivery to the central nervous system (CNS), for the therapeutic advancement of neurodegenerative disorders such as Alzheimer's, is complicated by restrictive mechanisms imposed at the blood-brain barrier (BBB). Opsonization by plasma proteins in the systemic circulation is an additional impediment to cerebral drug delivery. This review gives an account of the BBB and discusses the literature on biodegradable polymeric nanoparticles (NPs) with appropriate surface modifications that can deliver drugs of interest beyond the BBB for diagnostic and therapeutic applications in neurological disorders, such as AD. The physicochemical properties of the NPs at different surfactant concentrations, stabilizers, and amyloid-affinity agents could influence the transport mechanism.

Selective targeting of antibody-conjugated nanoparticles to leukemic cells and primary T-lymphocytes

In the present study, surface-modified nanoparticles based on biodegradable material were used for antibody coupling in order to get a selective drug carrier systems. Gelatin nanoparticles were prepared by a desolvation process. Sulfhydryl groups were introduced which enabled the linkage of NeutrAvidin (NAv). Antibodies specific for the CD3 antigen on lymphocytic cells were conjugated to the nanoparticles surface. The binding of biotinylated anti-CD3 antibody was achieved by NAv-biotin-complex formation. Cellular binding and uptake were determined by flow cytometry and confocal laser scanning microscopy (CLSM). Cell-type-specific targeting of anti-CD3-conjugated nanoparticles into CD3-positive human T-cell leukemia cells and primary T-lymphocytes could be shown. Celluar uptake and effective internalization of antibody-conjugated nanoparticles into CD3 expressing cells were demonstrated. Uptake rates of about 84% into T-cell leukemia cells were observed. To confirm selectivity of T-cell targeting, competition experiments were carried out adding excessive free anti-CD3 prior to nanoparticle incubation leading to significantly reduced cellular uptake of antibody-conjugated nanoparticles. Further analysis on the mechanism of uptake confirmed a receptor-mediated endocytotic process. Protein-based nanoparticles conjugated with an antibody against a specific cellular antigen hold promise as selective drug delivery systems for specific cell types.

Pharmacokinetics, tissue distribution and bioavailability of clozapine solid lipid nanoparticles after intravenous and intraduodenal administration

Clozapine, a lipophilic effective atypical antipsychotic drug, has very poor oral bioavailability (<27%) due to first pass effect. Clozapine solid lipid nanoparticles have been developed using various triglycerides (trimyristin, tripalmitin and tristearin), soylecithin 95%, poloxamer 188 and stearylamine as a positive charge inducer by hot homogenization followed by ultrasonication method. Particle size and charge measurements were made with Malvern Zetasizer. Pharmacokinetics of clozapine incorporated in solid lipid nanoparticles (SLNs), after intravenous (i.v.) administration to conscious male Wistar rats were studied. The aim of this research was to find out whether the bioavailability of clozapine can be improved by administering clozapine SLN duodenally to rats. Tissue distribution studies of clozapine SLN and suspension were carried out in Swiss albino mice. Average size and zeta potential of SLNs of different lipids with stearylamine ranged from 96.7+/-3.8 to 163.3+/-0.7 nm and 21.3+/-1.3 to 33.2+/-0.6 mV, respectively. AUC((0-infinity)) was increased (up to 2.91-fold) and clearance was decreased (up to 2.93-fold) when clozapine entrapped in SLNs with stearylamine were administered intravenously. Bioavailability of clozapine SLNs were 2.45- to 4.51-fold after intraduodenal administration compared with that of clozapine suspension. In tested organs, the AUC and MRT of clozapine SLNs were higher than those of clozapine suspension especially in brain and reticuloendothelial cell-containing organs. These results indicate that SLN are suitable drug delivery system for the improvement of bioavailability of lipophilic drugs such as clozapine.

Peptide-derivatized biodegradable nanoparticles able to cross the blood-brain barrier

Injectable nanoparticulate drug carriers (Np) able to cross the blood-brain barrier (BBB) have important potential applications for the treatment of diseases that affect the central nervous system (CNS). With the aim to create a system able to address Np to the CNS, we synthesized conjugates between a biodegradable copolymer, poly(D,L-lactide-co-glycolide) (PLGA), and five short peptides, by means of an amidic linkage. These peptides, that are similar to synthetic opioid peptides, were synthesized in turn by means of Fmoc solid-phase peptide synthesis. The new five modified copolymers thus obtained turned out to be valuable starting material for the preparation of Np; these were made fluorescent, in order to allow their localization after their administration, by inclusion of a fluorescent probe. The Np thus prepared were characterized (morphology, size and z-potential) and were shown to possess the peptidic moieties on their surface, as evidenced by ESCA spectroscopy. Then, their ability to cross the BBB was assessed by the in vivo Rat Brain Perfusion Technique and, in one case, by means of a systemic administration (rat femoral vein injection). Fluorescent and confocal microscopy studies showed that while PLGA Np are unable to cross the BBB, for the first time these solid Np surface-modified with peptides were shown to be able to cross the BBB.

Reorganization of lipid nanocapsules at air–water interface

The state, electrical and dilatational rheological properties of surface films formed at air-water interface from lipid nanocapsules (LNC) with various compositions as well as model monolayers formed by the LNC constituents-Labrafac, Solutol and Lipoid are investigated. These nanocapsules constitute potential drug delivery systems where lypophilic drug will be loaded in their core. The study of the model Labrafac/Solutol (Lab/Sol) mixed monolayers shows behavior close to the ideal. Small negative deviations in the mean molecular areas a and dipole moments mu are observed. All studied monolayers have elastic behavior during the small continuous compressions. The comparison between the properties of surface films formed from LNC with those of the model monolayers confirms the idea developed in the kinetic study that the surface films formed after a rapid disaggregation of the unstable nanocapsule fraction (LNC I) contains mainly Labrafac and Solutol. The Labrafac molar part (xLab) in the formed Lab/Sol mixed layer is established.

Nanoparticle and other metal chelation therapeutics in Alzheimer disease

Current therapies for Alzheimer disease (AD) such as the anticholinesterase inhibitors and the latest NMDA receptor inhibitor, Namenda, provide moderate symptomatic delay at various stages of disease, but do not arrest disease progression or supply meaningful remission. As such, new approaches to disease management are urgently needed. Although the etiology of AD is largely unknown, oxidative damage mediated by metals is likely a significant contributor since metals such as iron, aluminum, zinc, and copper are dysregulated and/or increased in AD brain tissue and create a pro-oxidative environment. This role of metal ion-induced free radical formation in AD makes chelation therapy an attractive means of dampening the oxidative stress burden in neurons. The chelator desferioxamine, FDA approved for iron overload, has shown some benefit in AD, but like many chelators, it has a host of adverse effects and substantial obstacles for tissue-specific targeting. Other chelators are under development and have shown various strengths and weaknesses. In this review, we propose a novel system of chelation therapy through the use of nanoparticles. Nanoparticles conjugated to chelators show a unique ability to cross the blood-brain barrier (BBB), chelate metals, and exit through the BBB with their corresponding complexed metal ions. This method may prove to be a safe and effective means of reducing the metal load in neural tissue thus staving off the harmful effects of oxidative damage and its sequelae.

Poly(ethylene oxide)-modified poly(epsilon-caprolactone) nanoparticles for targeted delivery of tamoxifen in breast cancer

This study was carried out to evaluate and compare the biodistribution profile of tamoxifen when administered intravenously (i.v.) as a simple solution or when encapsulated in polymeric nanoparticulate formulations, with or without surface-stabilizing agents. Tamoxifen-loaded, poly(ethylene oxide)-modified poly(epsilon-caprolactone) (PEO-PCL) nanoparticles were prepared by solvent displacement process that allowed in situ surface modification via physical adsorption of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock polymeric stabilizer (Pluronic). The nanoparticles were characterized for particle size and surface charge. Presence of PEO chains on nanoparticle surface was ascertained by electron spectroscopy for chemical analysis (ESCA). In vivo biodistribution studies were carried out in Nu/Nu athymic mice bearing a human breast carcinoma xenograft, MDA-MB-231 using tritiated [(3)H]-tamoxifen as radio-marker for quantification. PEO-PCL nanoparticles with an average diameter of 150-250 nm, having a smooth spherical shape, and a positive surface charge were obtained with the formulation procedure. About 90% drug encapsulation efficiency was achieved when tamoxifen was loaded at 10% by weight of the polymer. Aqueous wettability, suspendability, and ESCA results showed surface hydrophilization of the PCL nanoparticles by the Pluronics. The primary site of accumulation for the drug-loaded nanoparticles after i.v. administration was the liver, though up to 26% of the total activity could be recovered in tumor at 6h post-injection for PEO-modified nanoparticles. PEO-PCL nanoparticles exhibited significantly increased level of accumulation of the drug within tumor with time as well as extended their presence in the systemic circulation than the controls (unmodified nanoparticles or the solution form). Pluronic surfactants (F-68 and F-108) presented simple means for efficient surface modification and stabilization of PCL nanoparticles to achieve preferential tumor-targeting and a circulating drug reservoir for tamoxifen.

Glial cell line-derived neurotrophic factor-conjugated nanoparticles suppress acquisition of cocaine self-administration in rats

The neurotrophic factor glial cell line-derived neurotrophic factor (GDNF) may have therapeutic potential for preventing and treating cocaine addiction. Previously, we found that transplantation of a GDNF-expressing astrocyte cell line into the striatum and nucleus accumbens attenuates cocaine-seeking behavior in Sprague-Dawley rats. However, as a potential treatment for humans, cell transplantation presents several technical and ethical complications. Nanoparticulate systems are a safe and effective method for introducing exogenous compounds into the brain. Therefore, we examined the effect of GDNF-conjugated nanoparticles microinjected into the striatum and nucleus accumbens on cocaine self-administration in rats. GDNF-conjugated nanoparticles blocked the acquisition of cocaine self-administration compared to control treatments. Furthermore, a cocaine dose response demonstrated that decreased lever response in rats that received GDNF-conjugated nanoparticles persisted after substitution with different cocaine doses. This effect is not due to a non-specific disruption of locomotor or operant behavior, as seen following a water operant task. The current study is one of the first demonstrations that drug-conjugated nanoparticles may be effective in treating brain disorders. These findings suggest that GDNF-conjugated nanoparticles may serve as a novel potential treatment for drug addiction.

[Pt(HPxSC)Cl3], a novel platinum(IV) compound with anticancer properties

There has been a continuing effort for the discovery of novel platinum(IV)-based antitumor compounds with better therapeutic performances than cisplatin. In the present work, the anticancer action of recently synthesized Pt(IV)-based complex [Pt(HPxSC)Cl(3)] was investigated using rat and human astrocytoma cell lines C6 and U251. [Pt(HPxSC)Cl(3)] markedly reduced the number of cultured astrocytoma cells (IC(50), 80 microM), as determined by crystal violet assay. The Pt(IV) complex induced apoptotic death of tumor cells, as flow cytometry analysis of the propidium iodide-stained cellular DNA revealed approx. 30% of hypodiploid cells in [Pt(HPxSC)Cl(3)]-treated astrocytoma cell cultures. On the other hand, [Pt(HPxSC)Cl(3)] at 200 microM did not affect the viability of rat primary astrocytes, unlike the established anticancer drug cisplatin, which displayed high toxicity toward both astrocytoma cells (IC(50), 15 microM) and primary astrocytes (IC(50), 20 microM). Moreover, [Pt(HPxSC)Cl(3)] at 100 microM did not interfere with the ability of rat peritoneal macrophages to produce important antitumor molecules nitric oxide and tumor necrosis factor-alpha. Finally, we assessed the ability of [Pt(HPxSC)Cl(3)] to restrain growth of some bacterial and yeast strains, but it showed rather limited antimicrobial activity.

Preparation and in vitro evaluation of chitosan nanoparticles containing a caspase inhibitor

The aim of this work was to develop a formulation for Z-DEVD-FMK, a peptide which is a caspase inhibitor and has been used in experimental animal studies for a decade. Peptide loaded chitosan nanoparticles were obtained by ionotropic gelation process and Z-DEVD-FMK was quantified by an HPLC method. The influence of the initial peptide concentration on the nanoparticle characteristics and release behavior was evaluated. The CS nanoparticles have a particle diameter (Z-average) ranging from approximately 313-412 nm and a positive zeta potential (20-28 mV). The formulation with the initial peptide concentration of 400 ng/ml provided the highest loading capacity (0.46%) and the highest extent of release (65% at 24 h) suggesting the possibility to achieve a therapeutic dose. According to the data obtained, this chitosan-based nanotechnology opens new and interesting perspectives for anticaspase activity.

Nanotoxicology: an emerging discipline evolving from studies of ultrafine particles

Although humans have been exposed to airborne nanosized particles (NSPs; < 100 nm) throughout their evolutionary stages, such exposure has increased dramatically over the last century due to anthropogenic sources. The rapidly developing field of nanotechnology is likely to become yet another source through inhalation, ingestion, skin uptake, and injection of engineered nanomaterials. Information about safety and potential hazards is urgently needed. Results of older biokinetic studies with NSPs and newer epidemiologic and toxicologic studies with airborne ultrafine particles can be viewed as the basis for the expanding field of nanotoxicology, which can be defined as safety evaluation of engineered nanostructures and nanodevices. Collectively, some emerging concepts of nanotoxicology can be identified from the results of these studies. When inhaled, specific sizes of NSPs are efficiently deposited by diffusional mechanisms in all regions of the respiratory tract. The small size facilitates uptake into cells and transcytosis across epithelial and endothelial cells into the blood and lymph circulation to reach potentially sensitive target sites such as bone marrow, lymph nodes, spleen, and heart. Access to the central nervous system and ganglia via translocation along axons and dendrites of neurons has also been observed. NSPs penetrating the skin distribute via uptake into lymphatic channels. Endocytosis and biokinetics are largely dependent on NSP surface chemistry (coating) and in vivo surface modifications. The greater surface area per mass compared with larger-sized particles of the same chemistry renders NSPs more active biologically. This activity includes a potential for inflammatory and pro-oxidant, but also antioxidant, activity, which can explain early findings showing mixed results in terms of toxicity of NSPs to environmentally relevant species. Evidence of mitochondrial distribution and oxidative stress response after NSP endocytosis points to a need for basic research on their interactions with subcellular structures. Additional considerations for assessing safety of engineered NSPs include careful selections of appropriate and relevant doses/concentrations, the likelihood of increased effects in a compromised organism, and also the benefits of possible desirable effects. An interdisciplinary team approach (e.g., toxicology, materials science, medicine, molecular biology, and bioinformatics, to name a few) is mandatory for nanotoxicology research to arrive at an appropriate risk assessment.

Optical and MRI multifunctional nanoprobe for targeting gliomas

A multifunctional nanoprobe capable of targeting glioma cells, detectable by both magnetic resonance imaging and fluorescence microscopy, was developed. The nanoprobe was synthesized by coating iron oxide nanoparticles with covalently bound bifunctional poly(ethylene glycol) (PEG) polymer, which were subsequently functionalized with chlorotoxin and the near-infrared fluorescing molecule Cy5.5. Both MR imaging and fluorescence microscopy showed significant preferential uptake of the nanoparticle conjugates by glioma cells. Such a nanoprobe could potentially be used to image resections of glioma brain tumors in real time and to correlate preoperative diagnostic images with intraoperative pathology at cellular-level resolution.

Double-Coated Poly (Butylcynanoacrylate) Nanoparticulate Delivery Systems for Brain Targeting of Dalargin Via Oral Administration

The aim of this study is to evaluate oral administration of poly (butylcyanoacrylate) nanoparticulate delivery systems (PBCA-NDSs), double-coated with Tween 80 and poly (ethylene) glycol (PEG) 20000 for brain delivery of hexapeptide dalargin, an anti-nociceptive peptide that does not cross blood-brain barrier (BBB) by itself. Studies have proven the brain uptake of Tween 80 overcoated nanoparticles after intravenous administration, but studies for brain delivery of nanoparticles after oral administration had been limited due to reduced bioavailability of nanoparticles and extensive degradation of the peptide and/or nanoparticles by gastrointestinal enzymes. To address this problem, dalargin-loaded PBCA-NDS were successively double-coated with Tween 80 and PEG 20000 in varied concentrations of up to 2% each. Measurement of in vivo central anti-nociceptive effect of dalargin along with a dose response curve was obtained by the tail flick test following the oral administration of PBCA-NDSs to mice. Results from the tail flick test indicated that significant dalargin-induced analgesia was observed from PBCA-NDSs with double-coating of Tween and PEG in comparison with single-coating of either Tween or PEG. Hence, it could be concluded that surface coated PBCA-NDS can be used successfully for brain targeting of dalargin or other peptides administered orally. However, further studies are required to elucidate the exact transport mechanism of PBCA-NDSs from gastrointestinal tract to brain.

N-methyl-D-aspartate receptors mediate endogenous opioid release in enteric neurons after abdominal surgery

BACKGROUND & AIMS

We tested the hypothesis that N-methyl-D-aspartate (NMDA) receptors mediate surgery-induced opioid release in enteric neurons.

METHODS

We used mu opioid receptor (muOR) internalization as a measure of opioid release with immunohistochemistry and confocal microscopy. MuOR internalization was quantified in enteric neurons from nondenervated and denervated ileal segments of guinea pig after abdominal laparotomy with and without pretreatment with NMDA-receptor antagonists acting at different recognition sites (+)-5-methyl-10,11-dihydro-5H-dibenzo [a,b] cyclohepten-5,10-imine (MK-801) or (D) 2-amino-5-phosphopenoic acid (AP-5) at .5, 1 mg/kg; 8-chloro-4-hydroxy-1-oxo-1,2-dihydropyridazinol [4,5-]quinoline-5-oxide choline (MRZ 2/576) or 8-chloro-1,4-dioxo-1,2,3,4-tetrahydropyridazinol [4,5-]quinoline choline salt (MRZ 2/596) at .3, 1 mg/kg, or with an antagonist for the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, 6-cyano-7-nitroquinoxaline-2,3-dione (1, 3 mg/kg). To determine whether NMDA stimulation induces opioid release, (1) ilea were exposed to NMDA (100 micromol/L) and D-serine (10 micromol/L) with or without the antagonist MK-801 or AP-5 (50 micromol/L); and (2) neuromuscular preparations of the ileum were stimulated electrically (20 Hz, 20 min) with or without MK-801 or AP-5 (50 micromol/L).

RESULTS

MuOR endocytosis induced by abdominal laparotomy was inhibited significantly by NMDA-receptor antagonists in nondenervated and denervated ileal segments, but not by the AMPA-receptor antagonist. MuOR endocytosis in neurons exposed to NMDA or electrical stimulation was prevented by NMDA-R antagonists.

CONCLUSIONS

Abdominal laparotomy evokes local release of glutamate that results in endogenous opioid release through the activation of peripheral NMDA receptors. This suggests an interaction between the glutamatergic and opioid systems in response to the noxious and perhaps mechanosensory stimulation of surgery.