Long spacer arm-functionalized magnetic nanoparticle platform for enhanced chemiluminescent detection of hepatitis B...

A simple and cost-effective platform based on conjugating long spacer arms (LSA) onto magnetic nanoparticles (MNPs) was developed to enhance the chemiluminescent (CL) detection of pathogens. The modification method is both convenient and practical because it utilizes the commercially available macromolecule, carboxymethylated glucan (CMG), as the LSA. CMG-MNPS are designed to have low steric hindrance and high suspension properties, which allow for facile modification and hybridization reactions that enhance the CL sensitivity and detection. The infectious pathogen, hepatitis B virus (HBV) was selected for feasibility testing on this platform. The biotinylated amplicon of HBV, obtained by polymerase chain reaction (PCR), was hybridized to DNA probes functionalized on CMG-MNPs. The magnetic complexes were then incubated with streptavidin-alkaline phosphatase (SA-AP) to form linkages through biotin-streptavidin interactions. Finally, the magnetic complexes were mixed with 3-(2'-spiroadamantyl)-4-methoxy-4-(3"-phosphoryoxy)-phenyl-1,2-dioxetane (AMPPD) to generate CL signals that were proportional to the concentration of the HBV target. The detection of HBV with CMG-MNPs was more sensitive than that with the conventional carboxylated MNPs (CMNPs, succinic anhydride-modified MNPs). When optimized, the novel method showed high specificity and a detection limit of 0.5 pM. This new platform shows promise for the early clinical diagnosis of infectious diseases.