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Asymmetrical flow field-flow fractionation (AF4) coupled with UV-vis spectrophotometry, multiangle light scattering (MAILS), and dynamic light scattering (DLS) detection was used to analyze dispersions of DNA/ rhodamine B labeled chitosan (Ch-rho) complexes frequently used as gene delivery vectors. The method yielded, in a single experiment, important characteristics of the complexes, such as their hydrodynamic radius, size distribution, conformation, composition, and the amount of free Ch-rho in the dispersions. Samples for analysis were obtained by varying experimental parameters known to influence the transfection efficiency of DNA/chitosan complexes, including the DNA concentration at mixing (82-164 [micro]g/mL), the ratio of chitosan amino groups to DNA phosphate groups (3 [less than or equal to] N/P ratio [less than or equal to] 15), the chitosan molecular weight (10-76 kDa), and its degree of deacetylation. In all preparations, DNA/Ch-rho complexes had hydrodynamic radii ranging from 15 to 160 nm. Both the DNA concentration and the Ch-rho molecular weight influence the size distribution of the complexes: a greater fraction of large particles was detected in dispersions prepared with the most concentrated DNA solution or the Ch-rho of highest molar mass. All dispersions contained free Ch-rho in solution. The free Ch-rho content ranged from 53 to 92% of the total Ch-rho concentration in dispersions prepared with N/P ratios from 3 to 15, respectively, implying that the N/P ratio of the complexes ranged from 1.3 to 1.6 in all samples. The accuracy of the free Ch-rho determination by AF4/UV-vis/MALS+DLS was confirmed by an independent method involving (1) ultracentrifugation of the dispersions prepared with unlabeled chitosan and (2) analysis of the supernatant by the Orange II dye depletion method. This study demonstrates the ability of AF4/UV-vis/MALS+DLS to provide a complete physicochemical characterization of DNA/polycation complexes used in nonviral gene delivery. 10.1021/ac100711j

Fluorescence spectroscopy and isothermal titration calorimetry (ITC) is used to study the intermixing in water of fluorescently labeled poly(N-isopropylacrylamides) grafted at random with low levels of either fluorocarbon or hydrocarbon chains. The spectroscopic measurements relied on the photophysics of pyrene and naphthalene chromophores grafted along the polymer backbone.

1. Introduction Human diseases can be treated by the transfer of therapeutic genes (transgene) into specific cells or tissues of patients to correct or supplement defective, causative genes. The success [...], 50kDa chitosan was conjugated with folate, a specific tissue-targeting ligand. Nanoparticles such as chitosan-DNA and folate-chitosan-DNA were prepared by coacervation process. The hydrodynamic intravenous injection of nanoparticles was performed in the right posterior paw in normal and arthritic rats. Our results demonstrated that the fluorescence intensity of DsRed detected was 5 to 12 times more in the right soleus muscle and in the right gastro muscle than other tissue sections. β-galactosidase gene expression with X-gal substrate and folate-chitosan-plasmid nanoparticles showed best coloration in the soleus muscle. Treated arthritic animals also showed a significant decrease in paw swelling and IL-1β and [PGE.sub.2] concentration in serum compared to untreated rats. This study demonstrated that a nonviral gene therapeutic approach using hydrodynamic delivery could help transfect more efficiently folate-chitosan-DNA nanoparticles in vitro/in vivo and could decrease inflammation in arthritic rats.

Transmission electron microscopy (TEM), dynamic light scattering (DLS) and high sensitivity differential scanning calorimetry (HS-DSC) were used to characterize the linear copolymers of ethylene and acrylic acid (PEAA) nanoparticles prepared by catalytic polymerization of ethylene and tert-butyl acrylate followed by hydrolysis of the ester groups. The PEAA nanoparticles which dispersed in aqueous media exhibited a remarkable reversible thermoresponsive behavior upon heating/cooling from 25 to 80 degree [Celsius].