Multiplexed homogeneous digital immunoassay based on single-particle motion analysis
LAB ON A CHIP
Authors: Akama, Kenji; Noji, Hiroyuki
Abstract
Homogeneous digital immunoassay is a powerful analytical method for highly sensitive protein biomarker detection with a simple protocol. However, it has not been multiplexed yet. In this study, we developed a multiplexed homogeneous digital immunoassay based on single-particle motion analysis (digital homogeneous non-enzyme-linked immunosorbent assay, digital Ho-Non ELISA). In this assay, multiple target antigen molecules react with the optical subpopulation of magnetic nanobeads labeled with fluorescent dyes and capture antigen-specific antibodies. Then, these beads are magnetically pulled into femtoliter-sized reactors. The surface of these reactors is modified with multiple detection antibodies specific to each antigen by molecular tethers. Each antigen on the particles reacts with the detection antibodies anchored to the surface of the reactors. Magnetic force enhances the efficiency of bead encapsulation in the reactors, and subsequent physical compartmentalization of beads enhances the binding efficiency of the antigen-antibody reaction. The tethered beads show characteristic Brownian motion distinct from free diffusion or non-specific binding of the antigen-free beads. The color of the beads is attributed to target-identification, and the number of tethered beads is attributed to the concentration of the specific target. We measured two biomarkers (PSA and IL6) as model targets by multiplexed digital Ho-Non ELISA. Our method showed higher sensitivity compared to previous digital Ho-Non ELISA and could detect multiple targets simultaneously with the same performance as in single-plex detection. This new strategy has the potential to open a new avenue for next-generation multiplexed immunoassays inin vitrodiagnostics.
Chlamydia muridarum infection differentially alters smooth muscle function in mouse uterine horn and cervix
AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM
Authors: Lee, Jia Ming; Mayall, Jemma R.; Chevalier, Anne; McCarthy, Huw; Van Helden, Dirk; Hansbro, Philip M.; Horvat, Jay C.; Jobling, Phillip
Abstract
Chlamydia trachomatis infection is a primary cause of reproductive tract diseases including infertility. Previous studies showed that this infection alters physiological activities in mouse oviducts. Whether this occurs in the uterus and cervix has never been investigated. This study characterized the physiological activities of the uterine horn and the cervix in a Chlamydia muridarum (Cmu)-infected mouse model at three infection time points of 7, 14, and 21 days postinfection (dpi). Cmu infection significantly decreased contractile force of spontaneous contraction in the cervix (7 and 14 dpi; P < 0.001 and P < 0.05, respectively), but this effect was not observed in the uterine horn. The responses of the uterine horn and cervix to oxytocin were significantly altered by Cmu infection at 7 dpi (P < 0.0001), but such responses were attenuated at 14 and 21 dpi. Cmu infection increased contractile force to prostaglandin (PGF(2 alpha)) by 53-83% in the uterine horn. This corresponded with the increased messenger ribonucleic acid (mRNA) expression of Ptgfr that encodes for its receptor. However. Cmu infection did not affect contractions of the uterine horn and cervix to PGE(2) and histamine. The mRNA expression of Otr and Ptger4 was inversely correlated with the mRNA expression of Il1b, Il6 in the uterine horn of Cmu-inoculated mice (P < 0.01 to P < 0.001), suggesting that the changes in the Otr and Ptger4 mRNA expression might be linked to the changes in inflammatory cytokines. Lastly, this study also showed a novel physiological finding of the differential response to PGE(2) in mouse uterine horn and cervix.