RESUMO
A graftable LDV (Leu-Asp-Val) peptidomimetic molecule (B-c) has been prepared from 3-(5-amino-2-hydroxy)phenyl-propionic acid, as alpha(4)beta(1) (VLA-4) integrin ligand. For that purpose, the mechanism of 3-(4-azidophenyl)propionic acid rearrangement has been revisited. Activation of Durapore DVPP-hydrophilic membrane, by surface wet chemistry using triazine trifluoride, followed by covalent coupling of B-c produced a modified filter (0.8% of derivatisation from XPS analysis) with improved capacity of leukocyte retention.
Assuntos
Integrina alfa4beta1/efeitos dos fármacos , Leucócitos/efeitos dos fármacos , Oligopeptídeos/síntese química , Fenilpropionatos/química , Sequência de Aminoácidos , Desenho de Fármacos , Humanos , Integrina alfa4beta1/sangue , Membranas Artificiais , Mimetismo Molecular , Estrutura Molecular , Oligopeptídeos/sangue , Polivinil/química , Polivinil/metabolismo , Relação Estrutura-AtividadeRESUMO
The surface functionalization of PBT melt-blown membrane, making up a whole filter of blood components, was achieved via two methods. Hydroxyl chain-end activation by tosylation (method A), followed by coupling of F- and (3)H-tagged molecules (probes), led to 1% of surface derivatization (XPS) and 290 pmol/cm(2) of lysine fixation (LSC). Deposition of O-succinimidyl 4-(p-azido-phenyl)butanoate ("molecular clip") and 2 h irradiation at 254 nm led to the implanting of activated ester functions, randomly on the polymer surface (method B). Further coupling of F- and (3)H-probes by wet chemistry gave highly functionalized surface (4% by XPS and 1000 pmol/cm(2) by LSC). However, control experiments showed that about 80% of the surface derivatization resulted from the UV treatment alone. Thus, the effect of UV irradiation on PBT membrane was systematically studied and analyzed by XPS, contact angle measurements, GPC and surface reactivity assays. The optimized conditions of "molecular clip" photo-grafting (negligible polymer photo-oxidation/photo-degradation) led to the covalent fixation of 45 pmol/cm(2) of (3)H-probe. Throughout our study, the behaviour of PBT melt-blown membrane was compared to PBT film and PET track-etched membrane similarly treated. Lastly, the method B was applied to couple GRGDS peptide on the PBT membrane; this material showed improved properties of leukocyte depletion in buffy coat filtration experiments.
Assuntos
Azidas/química , Membranas Artificiais , Peptídeos/química , Poliésteres/química , Butiratos/química , Humanos , Leucócitos/química , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Fotoquímica , Polietilenotereftalatos/química , Succinimidas/química , Propriedades de SuperfícieRESUMO
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 nm 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.
