Polymerization kinetics of n-butyl cyanoacrylate glues used for vascular embolization.

Vascular embolization is a minimally invasive treatment used for the management of vascular malformations and tumors. It is carried out under X-ray by navigating a microcatheter into the targeted blood vessel, through which embolic agents are delivered to occlude the vessels. Cyanoacrylate liquid glues have been widely used for vascular embolization owing to their low viscosity, rapid polymerization/solidification rate, good penetration ability and low tissue toxicity. The objective of this study is to quantitatively investigate the physical properties of two n-butyl cyanoacrylate (nBCA) glues (Glubran 2 and Histoacryl) mixed with an iodized oil (Lipiodol) at various concentrations. We show that an homogeneous solution results from the mixing of the glue and Lipiodol, and that the viscosity, density and interfacial tension of the mixture increase with the proportion in Lipiodol. We have designed a new experimental setup to systemically characterize the polymerization kinetics of a glue mixture upon contact with an ionic solution. We observe that the whole polymerization process includes two phases: an interfacial polymerization that takes place at the interface as soon as the two liquids are in contact with a characteristic time scale of the order of the minute; a volumetric polymerization during which a reaction front propagates within the mixture bulk with a characteristic time scale of the order of tens of minutes. The polymerization rate, front propagation speed and volume reduction increase with the glue concentrations. It is the first time that such comprehensive results are obtained on liquid embolic agents.

Comparison of scanning electron microscopy, dynamic light scattering and analytical ultracentrifugation for the sizing of poly(butyl cyanoacrylate) nanoparticles.

Nanoparticles represent promising carriers for controlled drug delivery. This work focuses on the size and molecular mass characterization of polyalkylcyanoacrylate nanoparticles formed by anionic emulsion polymerization of butylcyanoacrylate in the presence of poloxamer 188 as a stabilizer. Three different methods were used to determine the size and size distribution of the particle populations: scanning electron microscopy (SEM), dynamic light scattering (DLS), and analytical ultracentrifugation (ANUC). SEM on freeze-dried and Au-shadowed samples showed a relatively narrow distribution of virtually spherical particles with a mean diameter of 167 nm. DLS yielded a monomodal distribution with hydrodynamic diameters around 199 nm (in the absence of additional stabilizer) or 184 nm (in the presence of 1% poloxamer 188). The size distribution determined by ANUC using sedimentation velocity analysis was somewhat more complex, the size of the most abundant particles being around 184 nm. Molar particle mass distributions centered around 2.3x10(9) g/mol. The advantages and disadvantages of the three sizing techniques are discussed.

Poly(butylcyanoacrylate) nanoparticles for topical delivery of 5-fluorouracil.

Poly(butylcyanoacrylate) nanoparticles (PBCN) as a drug carrier of 5-fluorouracil (5FU) intended for topical treatment of skin lesia were investigated. The presence of 5FU (as saline solution, pH 10-11) in the polymerization medium affected the polymerization as well as the nanoparticle formation by influencing the initiation of the polymerization reaction. 5FU acted as an initiator in the anionic polymerization of n-butylcyanoacrylate monomer through its nucleophilic nitrogen centers. The results obtained by GPC, 1H NMR, and X-ray diffraction allude to a possible mechanism of cytostatic immobilization in the polymer matrix, with evidence for both free and bound forms of the drug.

Comparaçäo entre os efeitos da mistura gelatina-resorcina-formaldeído (Colagel) e do n-butil-2-cianoacrilato (Histoacryl) na esofagoplastia cervical de coelhos (Oryctolagus cuniculus; Linnaeus 1758). Estudo clínico e morfológico / Comparative study between the effects of gelatin-resorcin-formaldehyde (Colagel) and n-butil-2-cianoacrilate (Histoacryl) in rabbit cervical esophagotony

Objetivou-se, tendo em vista as particularidades anatômicas e fisiológicas do esôfago e sua correlaçäo com a gênese de deiscências, estudar comparativamente os efeitos de dois adesivos cirúrgicos, Colagel e Hystoacril, no reforço de suturas para a síntese do órgäo. Os procedimentos, conduzidos em 18 leporinos da raça Nova Zelândia, buscaram, na ordem, investigar a evoluçäo clínica dos animais, bem como a macroscopia e a microscopia das feridas cirúrgicas, quanto à evoluçäo da cicatrizaçäo. Os resultados obtidos mostraram, clínica e macroscopicamente, alteraçöes de maior significado e, microscopicamente, predomínio de polimorfonucleares eosinófilos nas suturas recobertas pelo Colagel, comparativamente às mantidas como controle e às "protegidas" pelo Histoacryl. Houve retardo na cicatrizaçäo das feridas que receberam o Colagel