Sensitivity enhancement of a fiber-based interferometric optofluidic sensor.

Optofluidic sensors, which tightly bridge photonics and micro/nanofluidics, are superior candidates in point-of-care testing. A fiber-based interferometric optofluidic (FIO) sensor can detect molecular biomarkers by fusing an optical microfiber and a microfluidic tube in parallel. Light from the microfiber side coupled to the microtube leads to lateral localized light-fluid evanescent interaction with analytes, facilitating sensitive detection of biomolecules with good stability and excellent portability. The determination of the sensitivity with respect to the interplay between light and fluidics, however, still needs to be understood quantitatively. Here, we theoretically and experimentally investigate the relationship between refractive index (RI) sensitivity and individual geometrical parameters to determine the lateral localized light-fluid evanescent interaction. Theoretical analysis predicted a sensitive maximum, which could be realized by synergically tuning the fiber diameter d and the tube wall thickness t at an abrupt dispersion transition region. As a result, an extremely high RI sensitivity of 1.6×104 nm/RIU (σ=4074 nm/RIU), an order of magnitude higher than our previous results, with detection limit of 3.0×10-6 RIU, is recorded by precisely governing the transverse geometry of the setup. The scientific findings will guide future exploration of both new light-fluid interaction devices and biomedical sensors.

MMP-1/TIMP-1 expressions in rectal submucosa of females with obstructed defecation syndrome associated with internal rectal prolapse.

OBJECTIVE: To explore the MMP-1/TIMP-1 expressions in rectal submucosa of females with obstructed defecation syndrome (ODS) associated with internal rectal prolapse (IRP). METHODS: Fifty-six female patients with ODS associated with IRP were enrolled as Case group, and 43 female hemorrhoids of stages III-IV without constipation and IRP were enrolled as Control group. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and immunohistochemistry were performed to test the expressions of MMP-1/TIMP-1 in the rectal submucosa. Western blotting was used to examine protein expressions of MMP-1/TIMP-1 and pro-inflammatory cytokines (IL-6 and TNF-α) in the rectal submucosa. EVG staining was conducted to detect collagen and elastic fibers in rectal submucosa. RESULTS: The increased expression of MMP-1 was negatively linked to the decreased TIMP-1 level in the rectal submucosa of patients with ODS associated with IRP. Besides, the expressions of IL-6 and TNF-α were increased in the Case group as compared with the Control group. Additionally, ODS severity and the pro-inflammatory cytokines was positively linked to MMP-1, but negatively related to TIMP-1 in Case group. EVG staining showed that the area ratios of collagen and elastic fibers were lower in Case group than Control group. Through Pearson's correlation analysis, the area ratios of collagen and elastic fibers were positively associated with MMP-1 expression, but negatively correlated with TIMP-1 expression in rectal submucosa of patients with ODS associated with IRP. CONCLUSION: Elevated MMP-1 and reduced TIMP-1 were found in ODS associated with IRP, which was related to the ODS severity, inflammation and contents of collagen and elastic fibers.