A B S T R A C TEstimates of Asian emissions of air pollutants and carbonaceous aerosols and their mid-term projections have been changing significantly in the last years. The remote sensing community has shown that increase in NO x in Central East Asia is much stronger than any of the emission inventories or projections indicated so far. A number of studies reviewing older estimates appeared. Here, we review the key contributions and compare them to the most recent results of the GAINS model application for Asia and to the SRES projections used in the IPPC work. The recent projections indicate that the growth of emissions of SO 2 in Asia should slow down significantly towards 2010 or even stabilize at the current level. For NO x , however, further growth is projected although it will be most likely slower that in the last decade, owing to introduction of measures in transport. Emissions of carbonaceous aerosols (black carbon and organic carbon) are expected to decline after 2010, largely due to reduced use of biofuels in residential sector and efficiency improvements. The estimates of these emissions are burdened with significantly larger uncertainties than SO 2 and NO x ; even for the year 2000 the differences in estimates between studies are up to a factor of 2.

Carboxylated carbon nanotubes stand as the most promising nanovectors for biomedical and pharmaceutical applications due to their ease of covalent conjugation with eclectic functional molecules including therapeutic drugs, proteins, and oligonucleotides. In the present study, we attempt to investigate how the toxicity of acid-oxidized multiwalled carbon nanotubes (MWCNTs) can be tweaked by altering their degree of functionalization and correlate the toxicity trend with their biodistribution profile. In line with that rationale, mice were exposed to 10 mg/kg of pristine (p) and acid-oxidized (f) MWCNTs with varying degrees of carboxylation through a single dose of intravenous injection. Thereafter, extensive toxicity studies were carried out to comprehend the short-term (7 day) and long-term (28 day) impact of p- and various f-MWCNT preparations on the physiology of healthy mice. Pristine MWCNTs with a high aspect ratio, surface hydrophobicity, and metallic impurities were found to induce significant hepatotoxicity and oxidative damage in mice, albeit the damage was recovered after 28 days of treatment. Conversely, acid-oxidized carboxylated CNTs with shorter lengths, hydrophilic surfaces, and high aqueous dispersibility proved to be less toxic and more biocompatible than their pristine counterparts. A thorough scrutiny of various biochemical parameters, inflammation indexes, and histopathological examination of liver indicated that toxicity of MWCNTs systematically decreased with the increased functionalization density. The degree of shortening and functionalization achieved by refluxing p-MWCNTs with strong mineral acids for 4 h were sufficient to render the CNTs completely hydrophilic and biocompatible, while inducing minimal hepatic accumulation and inflammation. Quantitative biodistribution studies in mice, intravenously injected with Tc-99m labeled MWCNTs, clearly designated that clearance of CNTs from reticuloendothelial system (RES) organs such as liver, spleen, and lungs was critically functionalization density dependent. Well-individualized MWCNTs with shorter lengths (<500 nm) and higher degrees of oxidation (surface carboxyl density >3 μmol/mg) were not retained in any of the RES organs and rapidly cleared out from the systematic circulation through renal excretion route without inducing any obvious nephrotoxicity. As both p- and f-MWCNT-treated groups were devoid of any obvious nephrotoxicity, CNTs with larger dimensions and lower degrees of functionalization, which fail to clear out from the body via renal excretion route, were thought to be excreted via biliary pathway in faeces.

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The PEGylated PBCA formulation can work as a novel tool for drug delivery which can prevent RES uptake and prolong circulation half life.

Intranasal drug delivery is known to overcome the blood-brain barrier (BBB) for delivery of drugs to brain. The objective of this study was to prepare risperidone (RSP)-loaded solid lipid nanoparticles (RSLNs) and explore the possibility of brain targeting by nose-to-brain delivery. RSLNs were prepared by solvent emulsification-solvent evaporation method and characterized for drug content, particle size and size distribution, zeta potential, and in vitro drug-release study. The pharmacodynamic study of RSLNs, which was performed by paw test using Perspex platform, showed higher hindlimb retraction time (HRT) values as compared with RSP solution (RS) indicating the superiority of RSLNs over the RS for brain targeting. The pharmacokinetics and biodistribution studies in mice showed that brain/blood ratio 1 h post-administration of RSLNs (i.n.) was found to be 1.36 ± 0.06 (nearly 10- and 5-fold higher) as compared with 0.17 ± 0.05 for RS (i.v.) and 0.78 ± 0.07 for RSLNs (i.v.), respectively. Gamma scintigraphy imaging of mice brain following intravenous and intranasal administration confirmed the localization of drug in brain. This finding substantiates the existence of direct nose-to-brain delivery route for nanoparticles administered to the nasal cavity.