Multiplex immunoassays using surface modification-mediated porous layer open tubular capillary

Photonic crystal barcodes assembled from dendritic silica nanoparticles for the multiplex immunoassays of ovarian cancer biomarkers

The combined detection of CA125, CEA and AFP is of great significance in the diagnosis of ovarian cancer. Photonic crystal (PhC) barcodes have apparent advantages in multiplex immunoassays of ovarian cancer markers. In this paper, a novel PhC barcode was assembled from dendritic silica nanoparticles (dSiO₂) for multiplex detection of ovarian cancer biomarkers. The interconnected macroporous structure of the dSiO₂ PhC beads and the open porous topography of dendritic silica particles could increase the surface area to volume ratio for antibody immobilization. We simultaneously detected multiple ovarian cancer markers in one test tube using the sandwich immunization method by utilizing dSiO₂ PhC beads as a barcode and CdTe QDs as a detection signal. The detection limits of the three ovarian cancer markers, AFP, CEA and CA125, were 0.52 ng mL^-1, 0.64 ng mL^-1 and 0.79 U mL^-1, respectively (the signal-to-noise ratio was 3). Compared with the classic silica colloidal crystal bead (SCCB) suspension array, the sensitivity of the dSiO₂ PhC bead suspension array was increased. In addition, the results showed that this barcode suspension array had acceptable accuracy and good reproducibility.

A novel column modification approach for capillary gas chromatography: combination with a triptycene-based stationary phase achieves high separation performance and inertness

Integration of the novel column modification approach with a triptycene-based stationary phase achieves high-resolution performance and inertness towards acids/bases and isomers for capillary GC analysis.

Chemiluminescent Optical Fiber Immunosensor Combining Surface Modification and Signal Amplification for Ultrasensitive Determination of Hepatitis B Antigen

Optical fiber based immunosensors are very attractive for biomarker detection. In order to improve the sensor response, we propose a promising strategy which combines porous-layer modification of the fiber surface and streptavidin-biotin-peroxidase nano-complex signal amplification in chemiluminescent detection. Two hepatitis B antigens, hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg), are used as the targets for analysis using the proposed sensor. Comparing to immunoassays using normal optical fiber sensors, the response of the present sensor is enhanced by a factor of 4.8 and 6.7 for detection of HBsAg and HBeAg, respectively. The limit-of-quantitation of the proposed method is as low as 0.3 fg/mL (0.01 fg/mL) with a wide linear response range of 3 fg/mL–150 ng/mL (0.1 fg/mL–160 ng/mL) for sensing HBsAg (HBeAg). Quantitative determination of HBsAg and HBeAg in human serum samples is performed, showing the applicability of the proposed method for biomarker detection.

Capillary electrophoresis-immobilized enzyme microreactors for acetylcholinesterase assay with surface modification by highly-homogeneous microporous layer

We propose a new capillary electrophoresis (CE)-based open-tubular immobilized enzyme microreactor (OT-IMER) and its application in acetylcholinesterase (AChE) assays. The IMER is fabricated at the capillary inlet (reactor length of ∼1 cm) with the inner surface modified by a micropore-structured layer (thickness of ∼220 nm, pore size of ∼15-20 nm). The use of IMER accomplishes the enzymatic reaction and separation/detection of the products in the same capillary within 3 min. The feasibility of the proposed method is evaluated via online analysis of the activity and inhibition of AChE enzymes. Such method exhibits good reproducibility with relative standard deviation (RSD) of less than 4% for 20 runs, and the enzyme remains over 82% of the initial activity after usage of 7 days. The IMERs are successfully applied to detect the organophosphorus pesticide, paraoxon, in three types of vegetable juice samples with a limit of detection of as low as 61 ng mL^-1. Results show that the spiked samples are in the range of 89.6-105.9% with RSD less than 2.7%, thereby indicating its satisfactory level of accurate and reliable analysis of real samples by using the proposed method. Our study indicates that, with combination of advantages of both porous-layer capillary and CE OT-IMER, the proposed method is capable to enhance enzymatic reactions and to achieve rapid analysis with simple instrumentation and operation, thus would pave the way for extensive application of CE-based IMERs in a variety of bioanalysis.