Down's syndrome screening with hydrogel photonic barcodes

For giving birth to a healthy baby without Down's syndrome, screening the level of alpha fetoprotein (AFP) and free-beta human chorionic gonadotropin (β-hCG) in maternal serum has been a routine examination for all gravidas. However, many assays only detect one target once time, which requires large samples and is low-throughput and costly. Herein, we describe a sensitive and inexpensive multiplex detection assay based on inverse opal structure hydrogel barcodes with poly(ethylene glycol) diacrylate (PEG-DA), poly(ethylene glycol) (PEG) and acrylic acid (AA) hybrid components. The polymerized PEG-DA hydrogel could guarantee the stabilities of the inverse opal structure, while the AA could offer active carboxyl groups for the probe immobilization. In addition, the interconnected pores of the inverse opal structure caused by PEG could also provide channels for biomolecules diffusing and reaction into the voids of the barcodes. The immunoassay results of our detection on AFP and β-hCG showed acceptable accuracy and detection reproducibility, and the results were in acceptable agreement with those from common clinic method for the detection of practical clinical samples. Thus, the new platform is apparently suitable for multiplex detection of Down's syndrome.