A chemiluminescence enzyme immunoassay based on magnetic microparticles (MmPs-CLEIA) was developed to evaluate serum a-fetoprotein (AFP) in parallel with traditional colorimetric enzyme-linked immunosorbent assay (ELISA).A systematic comparison between the MmPs-CLEIA and colorimetric ELISA concluded that the MPs-CLEIA exhibited fewer dosages of immunoreagents,less total assay time,and better linearity,recovery,precision,sensitivity and validity.AFP was detected in forty human serum samples by the proposed MPs-CLEIA and ELISA,and the results were compared with commercial electrochemiluminescence immunoassay (ECLIA) kit.The correlation coefficient between MPs-CLEIA and ELISA was obtained with R 2 0.6703;however,the correlation between MPs-CLEIA and ECLIA (R 2 0.9582) was obviously better than that between colorimetric ELISA and ECLIA (R 2 0.6866).
Qian-Yun Zhang a,b,Hui Chen a,Zhen Lin a,Jin-Ming Lin a a Beijing Key Laboratory of Microanalytical Methods and Instrumentation,Department of Chemistry,Tsinghua University,Beijing 100029,China b Institute of Biophysics,Chinese Academy of Sciences,Beijing 100101,China
Glypican-3 （GPC3） is reported as a great promising tumor marker for hepatocellular carcinoma （HCC） diagnosis. Highly sensitive and accurate analysis of serum GPC3 （sGPC3）, in combination with or instead of traditional HCC marker alpha-fetoprotein （AFP）, is essential for early diagnosis of I-ICC. Biomaterial-functionalized magnetic particles have been utilized as solid supports with good biological compatibility for sensitive immunoassay. Here, the magnetic nanoparticles （MnPs） and magnetic microparticles （MmPs） with carboxyl groups were further modified with streptavidin, and applied for the development of chemiluminescence enzyme immunoassay （CLEIA）. After comparing between MnPs- and MmPs-based CLEIA, MnPs-based CLEIA was proved to be a better method with less assay time, greater sensitivity, better linearity and longer chemiluminescence platform. MnPs-based CLEIA was applied for detection of sGPC3 in normal liver, hepatocirrhosis, secondary liver cancer and HCC serum samples. The results indicated that sGPC3 was effective in diagnosis of HCC with high performance.
A simply fabricated microfluidic device integrated with a fluorescence detection system has been developed for on-line determination of ammonium in aqueous samples. A 365-nm light-emitting diode （LED） as an excitation source and a minor band pass filter were mounted into a polydimethylsiloxane （PDMS）-based microchip for the purpose of miniaturization of the entire analytical system. The ammonium sample reacted with o-phthaldialdehyde （OPA） on-chip with sodium sulfite as reducing reagent to produce a fluorescent isoindole derivative, which can emit fluorescence signal at about 425 nm when excited at 365 nm. Effects of pH, flow rate of solutions, concentrations of OPA-reagent, phosphate and sulfite salt were investigated. The calibration curve of ammonium in the range of 0.018- 1.8 μg/mL showed a good linear relationship with R2 = 0.9985, and the detection limit was （S /N = 3） 3.6 × 10 4 μg/mL. The relative standard deviation was 2.8% （n = 11） by calculating at 0.18 μg/mL ammonium for repeated detection. The system was applied to determine the ammonium concentration in rain and river waters, even extent to other analytes fluorescence detection by the presented device.
