Rapid three-dimensional biointerfaces for real-time immunoassay using hIL-18BPa as a model antigen

With the goal of designing a rapid and affordable system of real-time immune monitoring for future diagnostic applications in sepsis, we have developed a biointerface composed of polyethyleneimine (PEI) and carboxymethylcellulose (CMC) to provide a means of prompt and facile immunoassay. Biointerface assembly is complete within 30 min, with all preparation performed and monitored within the measurement chamber of a quartz crystal microgravimetry with dissipation (QCM-D) sensor. Optimised biointerface composition, as determined by the mass of antibody immobilised, the level of antigen detection, and the amount of nonspecific binding of human serum albumin, was determined to consist of a 4.0 mg/mL CMC hydrogel layer cross-linked to a 0.5 mg/mL PEI sub-layer. Tapping mode atomic force microscopy (AFM) in liquid demonstrates highly uniform and smooth surfaces using these hydrogels. Sensitivity of the biointerface for rhIL-18BPa is 400ng/mL, with detection of I mu g/mL achievable following 25 surface regenerations. Performance of the biointerface is verified using surface plasmon resonance (SPR), demonstrating the ability of the biointerface to be applied across platforms. (c) 2005 Elsevier Ltd. All rights reserved.