Showing results 21 to 26 of 26
  PEGylated quaternized copolymer/DNA complexes for gene delivery; ; Jérôme, Christine  et alin International Journal of Pharmaceutics (2007), 344(1-2), 88-95 The aim of this study was to improve the colloidal stability, decrease unspecific interactions with cells and blood components of a novel gene delivery system composed of epsilon-caprolactone and ... [more ▼] The aim of this study was to improve the colloidal stability, decrease unspecific interactions with cells and blood components of a novel gene delivery system composed of epsilon-caprolactone and quaternized epsilon-caprolactone. For this purpose, diblock 50/50 copolymer was used to generate complexes-with DNA by either the solvent evaporation technique and by dialysis. The size, surface charge and degree of interaction of the plasmid-loaded formulations were measured. Then, polyplexes were combined with a poly(CL)-b-PEG copolymer to create a hydrophilic corona on the surface of the complexes. The cytotoxicity, transfection efficiency and cellular uptake of polyplexes and their association with PEG were evaluated on HeLa cells. The dialysis method did not allow to reduce the size of complexes as compared to the solvent evaporation method. The zeta potential of polyplexes became positive from a charge ratio of 4. The degree of interaction of copolymer with plasmid DNA was very high. Cytotoxicity and transfection efficiency were found to be comparable to polyethylenimine 50 kDa. Association of polyplexes with poly(CL)-b-PEG copolymer led to a small increase in particle size and a sharp decrease of charge surface. Cytotoxicity, transfection efficiency and cellular uptake were significantly reduced relative to unshielded copolymer/DNA complexes. The PEGylated formulations may be an attractive approach for an in vivo application. [less ▲] Detailed reference viewed: 17 (2 ULg) PEGylated PLGA-based nanoparticles targeting M cells for oral vaccination; ; et al in Journal of Controlled Release (2007), 120(3), 195-204 To improve the efficiency of orally delivered vaccines, PEGylated PLGA-based nanoparticles displaying RGD molecules at their surface were designed to target human M cells. RGD grafting was performed by an ... [more ▼] To improve the efficiency of orally delivered vaccines, PEGylated PLGA-based nanoparticles displaying RGD molecules at their surface were designed to target human M cells. RGD grafting was performed by an original method called "photografting" which covalently linked RGD peptides mainly on the PEG moiety of the PCL-PEG, included in the formulation. First, three non-targeted formulations with size and zeta potential adapted to M cell uptake and stable in gastro-intestinal fluids, were developed. Their transport by an in vitro model of the human Follicle associated epithelium (co-cultures) was largely increased as compared to mono-cultures (Caco-2 cells). RGD-labelling of nanoparticles significantly increased their transport by co-cultures. due to interactions between the RGD ligand and the I intregrins detected at the apical surface of co-cultures. In vivo studies demonstrated that RGD-labelled nanoparticles particularly concentrated in M cells. Finally, ovalbumin-loaded nanoparticles were orally administrated to mice and induced an IgG response, attesting antigen ability to elicit an immune response after oral delivery. [less ▲] Detailed reference viewed: 57 (5 ULg)Monitoring of urea and potassium by reverse iontophoresis in vitro; ; Rozet, Eric et alin Pharmaceutical Research (2007), 24(6), 1131-1137 Purpose. Reverse iontophoresis is an alternative to blood sampling for the monitoring of endogenous molecules. Here, the potential of the technique to measure urea and potassium levels non-invasively, and ... [more ▼] Purpose. Reverse iontophoresis is an alternative to blood sampling for the monitoring of endogenous molecules. Here, the potential of the technique to measure urea and potassium levels non-invasively, and to track their concentrations during hemodialysis, has been examined. Materials and Methods. In vitro experiments were performed to test (a) a series of subdermal urea and potassium concentrations typical of the pathophysiologic range, and (b) a decreasing profile of urea and potassium subdermal concentrations to mimic those which are observed during hemodialysis. Results. (a) After 60-120 min of iontophoresis, linear relationships (p < 0.05) were established between both urea and potassium fluxes and their respective subdermal concentrations. The determination coefficients were above 0.9 after 1 h of current passage using sodium as an internal standard. (b) Reverse iontophoretic fluxes of urea and K+ closely paralleled the decay of the respective concentrations in the subdermal compartment, as would occur during a hemodialysis session. Conclusions. These in vitro experiments demonstrate that urea and potassium can be quantitatively and proportionately extracted by reverse iontophoresis, even when the subdermal concentrations of the analytes are varying with time. These results suggest the non-invasive monitoring of urea and potassium to diagnose renal failure and during hemodialysis is feasible, and that in vivo measurements are warranted. [less ▲] Detailed reference viewed: 60 (3 ULg)Improvement of the decision efficiency of the accuracy profile by means of a desirability function for analytical methods validation - Application to a diacetyl-monoxime colorimetric assay used for the determination of urea in transdermal iontophoretic extractsRozet, Eric ; ; et alin Analytica Chimica Acta (2007), 591(2), 239-247 Validation of analytical methods is a widely used and regulated step for each analytical method. However, the classical approaches to demonstrate the ability to quantify of a method do not necessarily ... [more ▼] Validation of analytical methods is a widely used and regulated step for each analytical method. However, the classical approaches to demonstrate the ability to quantify of a method do not necessarily fulfill this objective. For this reason an innovative methodology was recently introduced by using the tolerance interval and accuracy profile, which guarantee that a pre-defined proportion of future measurements obtained with the method will be included within the acceptance limits. Accuracy profile is an effective decision tool to assess the validity of analytical methods. The methodology to build such a profile is detailed here. However, as for any visual tool it has a part of subjectivity. It was then necessary to make the decision process objective in order to quantify the degree of adequacy of an accuracy profile and to allow a thorough comparison between such profiles. To achieve this, we developed a global desirability index based on the three most important validation criteria: the trueness, the precision and the range. The global index allows the classification of the different accuracy profiles obtained according to their respective response functions. A diacetyl-monoxime colorimetric assay for the determination of urea in transdermal iontophoretic extracts was used to illustrate these improvements. [less ▲] Detailed reference viewed: 63 (9 ULg)Helodermin-loaded nanoparticles: Characterization and transport across an in vitro model of the follicle-associated epithelium; ; et al in Journal of Controlled Release (2007), 118(3), 294-302 M cells represent a potential portal for oral delivery of peptides and proteins due to their high endocytosis abilities. An in vitro model of human FAE (co-cultures) was used to evaluate the influence of ... [more ▼] M cells represent a potential portal for oral delivery of peptides and proteins due to their high endocytosis abilities. An in vitro model of human FAE (co-cultures) was used to evaluate the influence of M cells on the transport of free and encapsulated helodermin - a model peptide - across the intestinal epithelium. M cells enhanced transport of intact helodermin (18-fold, Papp 3 X 10(-6) cm s(-1)). As pegylation increased nanoparticle transport by M cells, helodermin was encapsulated in 200 mu nanoparticles containing PEG-b-PLA:PLGA 1:1. Stability of the selected formulation was demonstrated in simulated gastric and intestinal fluids. M cells increased the transport of helodermin encapsulated in these nanoparticles by a factor of 415, as compared to Caco-2 cells. Transport of free and encapsulated helodermin occurred most probably by endocytosis. In conclusion, M cells improved helodermin transport across the intestinal epithelium, confirming their high potential for oral delivery of peptides. [less ▲] Detailed reference viewed: 52 (2 ULg)Copolymers of epsilon-caprolactone and quaternized epsilon-caprolactone as gene carriers; ; et al in Journal of Controlled Release (2007), 118(1), 136-144 New copolymers of E-caprolactone (CL) and gamma-bromo-epsilon-caprolactone quaternized by pyridine (Py + CL) were investigated as non-viral vectors for gene delivery. Copolymers with two molar ... [more ▼] New copolymers of E-caprolactone (CL) and gamma-bromo-epsilon-caprolactone quaternized by pyridine (Py + CL) were investigated as non-viral vectors for gene delivery. Copolymers with two molar compositions (50 Py + CL/50 CL and 80 Py + CL/20 CL), each with a diblock or a random structure, were used to prepare nanoparticulate complexes with DNA. Average size and surface charge of the complexes and extent of the complexation were measured. The DNA condensation by the copolymers was analysed by a gel retardation assay. Cytotoxicity and transfection efficiency of the copolymers were also evaluated in HeLa cells and compared with polyethylenimme 50 kDa. The size of the polyplexes was approximately 200 nm. The zeta potential first increased with the copolymer/DNA charge ratio and became positive for charge ratios in the 2-4 range depending on the type of copolymer. DNA was completely condensed within the nanoparticles and the degree of interaction was very high. Cytotoxicity and transfection efficiency were found to be comparable to polyethylenimine 50 kDa. The experimental results suggest that the novel copolymers can be used as novel gene delivery vectors. [less ▲] Detailed reference viewed: 20 (3 ULg)
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