Paper-based chemiluminescence ELISA: Lab-on-paper based on chitosan modified paper device and wax-screen-printing

A novel lab-on-paper device combining the simplicity and low-cost of microfluidic paper-based analytical devices (mu PADs) and the sensitivity and selectivity of chemiluminescence ELISA (CL-ELISA) for the high-throughput, rapid, stable and reusable point-of-care testing is presented here. Chitosan was used to modify mu PADs to covalently immobilize antibodies on mu PADs. Thus, sandwich CL-ELISA on mu PADs can be easily realized for further development of this technique in sensitive, specific and low-cost application. The paper device was fabricated by a low-cost, simple, and rapid wax-screen-printing method. Using tumor markers and paper microzone plate as model, the application test of this paper-based CL-ELISA was successfully performed with a linear range of 0.1-35.0 ng mL(-1) for alpha-fetoprotein, 0.5-80.0U mL(-1) for cancer antigen 125 and 0.1-70.0 ng mL(-1) for carcinoembryonic antigen. Since the cutoff values of the three tumor markers in clinical diagnosis are 25 ng mL(-1), 35U mL(-1) and 5 ng mL(-1), the sensitivity and linear ranges of the proposed method were enough for clinical application. In addition, this lab-on-paper immunodevice can provide reproducible results upon storage at 4 degrees C (sealed) for at least 5 weeks. Ultimately, this novel chitosan modification and wax-screen-printing methodology for mu PADs can be readily translated to other signal reporting mechanism including electrochemiluminescence and photoelectro-chemistry, and other receptors such as enzyme receptors and DNA receptors for determination of DNA, proteins and small molecules in point-of-care testing. (C) 2011 Elsevier B.V. All rights reserved.