[Colloids and Surfaces B: Biointerfaces] Polyethylene imine/graphene oxide layer-by-layer surface fu
Antibody immobilization on polymeric substrates is a key manufacturing step for microfluidic devices that implement sample-to-answer automation of immunoassays. In this work, a simple and versatile method to bio-functionalize poly(methylmethacrylate) (PMMA), a common material of such “Lab-on-a-Chip” systems, is proposed; using the Layer-by-Layer (LbL) technique, we assemble nanostructured thin films of poly(ethylene imine) (PEI) and graphene oxide (GO). The wettability of PMMA surfaces was significantly augmented by the surface treatment with (PEI/GO)5 film, with an 81% reduction of the contact angle, while the surface roughness increased by 600%, thus clearly enhancing wettability and antibody binding capacity. When applied to enzyme-linked immunosorbent assays (ELISAs), the limit of detection of PMMA surface was notably improved from 340 pg mL−1 on commercial grade polystyrene (PS) and 230 pg mL−1 on plain PMMA surfaces to 130 pg mL−1 on (PEI/GO)5 treated PMMA. Furthermore, the accelerated antibody adsorption kinetics on the LbL films of GO allowed to substantially shorten incubation times, e.g. for anti-rat IgG adsorption from 2 h down to 15 min on conventional and treated surfaces, respectively.
Celina M. Miyazakia, b, , , Rohit Mishraa, David J. Kinahana, Marystela Ferreirab, Jens Ducréea, , a National Centre for Sensor Research, School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland b Universidade Federal de São Carlos, CCTS, Rod. João Leme dos Santos, km 110, CEP 18052-780, Sorocaba, São Paulo, Brazil Received 20 March 2017, Revised 7 June 2017, Accepted 25 June 2017, Available online 27 June 2017