RESUMO
In this work, we clearly demonstrate the capability of protein nanopatterns of improving the quality factors of immunosensing devices, such as lowering of the limit of detection and increase of sensitivity. This beneficial effect is obtained by the formation on the sensor's surface of bioadhesive domains of nanometric dimensions in a nonadhesive matrix by means of colloidal lithography.
Assuntos
Nanoestruturas/química , Proteínas/química , Animais , Anticorpos Anti-Idiotípicos/química , Anticorpos Anti-Idiotípicos/imunologia , Anticorpos Monoclonais/química , Anticorpos Monoclonais/imunologia , Especificidade de Anticorpos , Reações Antígeno-Anticorpo , Humanos , Imunoglobulina G/química , Imunoglobulina G/imunologia , Nanotecnologia/métodos , Ovalbumina/química , Ovalbumina/imunologia , Polímeros/química , Soroalbumina Bovina/química , Soroalbumina Bovina/imunologiaRESUMO
Thermoresponsive polymer layers offer the possibility of preparing smart surfaces with properties that are switchable through a phase transition, usually close to the lower critical solution temperature of the polymer. In particular, poly( N-isopropylacrylamide) (pNIPAM) has gained a great deal of attention because it has such a phase transition in a physiologically interesting temperature range. We have prepared ultrathin thermoresponsive coatings by grafting pNIPAM on a plasma-CVD-deposited, poly(ethylene oxide)-like polymer substrate that was activated in an Ar plasma discharge to initiate the grafting. The presence and integrity of pNIPAM was verified by XPS and ToF-SIMS, and a dramatic change in the wettability during the phase transition was identified by temperature-dependent contact angle measurements. The transition from the hydrated to the collapsed conformation was analyzed by temperature-dependent QCM measurements and by AFM. An unusual, reversible behavior of the viscoelastic properties was seen directly at the phase transition from the swollen to the collapsed state. The phase transition leads to a switching from protein repulsion to a state that allows the adsorption of proteins.
Assuntos
Acrilamidas/química , Óxido de Etileno/química , Polímeros/química , Resinas Acrílicas , Adsorção , Animais , Materiais Biocompatíveis/química , Bovinos , Microscopia de Força Atômica , Conformação Molecular , Ligação Proteica , Proteínas/química , Albumina Sérica/química , Espectrometria por Raios X , Propriedades de Superfície , Temperatura , Raios XRESUMO
In this work, we compare the immunoreaction efficiency between uniformly functionalized surface and chemically nanopatterned surfaces when applied as platforms for antigen/antibody interactions with and without the use of protein A as orienting protein. On the nanopatterned platform, the immunoreaction efficiency is higher than all the other cases with no protein A pretreatment of the surface, providing evidence of the capability of the adhesive/antiadhesive nanopatterned surface to immobilize the molecules in a reactive state, increasing their possibility to form complexes.
Assuntos
Imunoensaio/instrumentação , Nanoestruturas/química , Antígenos/química , Humanos , Imunoglobulina G/química , Microscopia de Força Atômica , Proteína Estafilocócica A/química , Propriedades de SuperfícieRESUMO
Droplet formation during adsorption of the protein lactoferrin from an aqueous solution on a surface functionalized by plasma deposited poly(acrylic acid) is studied using quartz crystal microbalance and atomic force microscopy. The formation of protein droplets is particularly favored at pH values close to the isoelectric point of lactoferrin, where the molecules carry little excess charge and intermolecular attraction exceeds the molecule-surface interaction. By combining topographic data with information on the system dynamics, it is possible to describe the viscoelastic properties of the adsorbate within a quantitative model for nonhomogeneous layers.