RESUMO
Polydimethylsiloxane (PDMS) is an elastomer that is widely used in construction and for biological and biomedical applications. The biocompatibility of PDMS was improved by different surface treatment methods, i.e., plasma treatment or a combination of plasma treatment with UV-irradiation or redox initiator, to minimize the effects of deposition of salts and proteins. In this work we used the vinyl monomers sulfobetaine and AMPS which have good biocompatible properties.
Assuntos
Monofosfato de Adenosina/análogos & derivados , Betaína/análogos & derivados , Materiais Biocompatíveis/química , Dimetilpolisiloxanos/química , Plasma/química , Tionucleotídeos/química , Monofosfato de Adenosina/química , Albuminas/química , Betaína/química , Materiais Biocompatíveis/efeitos da radiação , Dimetilpolisiloxanos/efeitos da radiação , Hidrólise , Interações Hidrofóbicas e Hidrofílicas , Teste de Materiais , Estrutura Molecular , Peróxidos/química , Espectroscopia Fotoeletrônica , Polimerização , Sais/química , Silicones/química , Espectrofotometria Infravermelho , Propriedades de Superfície , Raios Ultravioleta , MolhabilidadeRESUMO
In order to prevent biofilm formation by Candida albicans, several cationic peptides were covalently bound to polydimethylsiloxane (PDMS). The salivary peptide histatin 5 and two synthetic variants (Dhvar 4 and Dhvar 5) were used to prepare peptide functionalized PDMS using 4-azido-2,3,5,6-tetrafluoro-benzoic acid (AFB) as an interlinkage molecule. In addition, polylysine-, polyarginine-, and polyhistidine-PDMS surfaces were prepared. Dhvar 4 functionalized PDMS yielded the highest reduction of the number of C. albicans biofilm cells in the Modified Robbins Device. Amino acid analysis demonstrated that the amount of peptide immobilized on the modified disks was in the nanomole range. Poly-d-lysine PDMS, in particular the homopeptides with low molecular weight (2500 and 9600) showed the highest activity against C. albicans biofilms, with reductions of 93% and 91%, respectively. The results indicate that the reductions are peptide dependent.
Assuntos
Antifúngicos/farmacologia , Peptídeos Catiônicos Antimicrobianos/química , Biofilmes/efeitos dos fármacos , Candida albicans/efeitos dos fármacos , Dimetilpolisiloxanos/química , Histatinas , Peptídeos/química , Peptídeos Catiônicos Antimicrobianos/síntese química , Peptídeos Catiônicos Antimicrobianos/farmacologia , Biofilmes/crescimento & desenvolvimento , Candida albicans/crescimento & desenvolvimento , Reagentes de Ligações Cruzadas , Histatinas/síntese química , Histatinas/química , Histatinas/farmacologia , Humanos , Testes de Sensibilidade Microbiana/instrumentação , Testes de Sensibilidade Microbiana/métodosRESUMO
New biocompatible materials have been obtained by different modifications of polydimethylsiloxane (PDMS) surfaces. PDMS is of great interest for several biomedical applications. For some applications the native silicone does not provide an optimal performance. PDMS attracts proteins and salts. To reduce protein adhesion and salt deposition selected monomers were grafted by radical polymerization on the silicone surface. The conditions for surface modifications of PDMS using benzophenone as UV initiator were optimized. The modified surfaces were characterized properly using different methods. The effect of surface modifications on the albumin, as model protein, deposition was tested in an in vitro model.
Assuntos
Benzofenonas/química , Dimetilpolisiloxanos/química , Adsorção , Materiais Biocompatíveis/química , Dimetilpolisiloxanos/síntese química , Estrutura Molecular , Espectroscopia Fotoeletrônica , Proteínas/química , Propriedades de SuperfícieRESUMO
A novel amphiphilic grafted copolymer, poly(vinylalcohol)-graft-poly(vinylnaphthalene), was synthesized and studied spectroscopically. The unusual photophysical properties of its aqueous solutions were observed for the first time and are attributed to the aggregation of the naphthalene chromophores in the bulk of polymer pseudomicelles. The enormous red shift of the fluorescence spectra is interpreted in terms of the confinement effect. The interpretation is supported by model calculations, taking into account the mixing of Frenkel excitons and charge-transfer states of chromophore clusters in densely packed polymer domains. Gradual funneling of the excitation energy between aggregates of different sizes is discussed in the context of the measured fluorescence depolarization spectra.
