Jae-Min Lim

Molecularly imprinted solid phase microextraction fiber for trace analysis of catecholamines in urine and serum samples by capillary electrophoresis.

A selective and flexible monolithic moleculary imprinted polymer (MIP) fiber was developed in batch for solid phase microextraction (SPME) of catecholamines (CAs), i.e., dopamine (DA), epinephrine (E) and norepinephrine (NE), and coupled with capillary electrophoresis (CE) for trace analysis of urine and serum samples. The polymer fiber was synthesized in-situ simply using a flexible capillary as a mold and the polymerization protocols and SPME experimental conditions were examined in detail. The reproducibility of fiber to fiber fabrication (n=5) was in range of 5.9-9.8% for three CAs. The fiber also shows high stability without any deterioration of extraction performance after 30 times use. Under the established optimum conditions, the limits of detection for DA, E, and NE were 7.4, 4.8, and 7.1 nmol L(-1), respectively, with the enhancement factor over 100 after MIP-SPME. The specific selectivity to three CAs was discovered with the developed MIP fibers compared with non-imprinted polymer (NIP) fiber. Finally, the MIP fibers were successfully applied for selective extraction of CAs in urine and serum samples with the relative recoveries ranging from 85% to 103%. The fabricated MIP-fibers were promising in preparation of biological samples in batch followed by CE-UV detection.

Rapid and selective determination of urinary lysozyme based on magnetic molecularly imprinted polymers extraction followed by chemiluminescence detection.

A rapid, low cost and selective chemiluminescence method coupled with magnetic molecularly imprinted polymers extraction was developed to detect lysozyme in human urine samples. Compared with traditional solid-phase extraction, this method could achieve selective extraction for the lysozyme, avoid the time consuming elution from a column or centrifugation steps, and then showed great potential in the high-throughput screening of clinical samples. The parameters affecting the performance of extraction and chemiluminescence were investigated. Under optimal conditions, the whole analytical procedure was completed within 12 min and spiked recovery ranged from 90.1% to 103.7% (R.S.D.≤6.7%). The limit of quantitation was 5 ng mL(-1). Furthermore, the results obtained by the proposed method were linearly correlated to those by commercial lysozyme detection kit (r=0.9595). Finally, the validated method was used to measure the urinary lysozyme of renal disease patients and healthy controls. The results confirmed the reliability and practicality of the protocol and revealed a good perspective of this method for biological sample analysis.

Synthesis and characterization of Eu3+ doped Gd2O3 nanotubes using multi wall carbon nanotubes as removable templates

Eu3+ doped Gd2O3 nanotubes have been synthesized using multi wall carbon nanotubes as removable templates by employing a liquid phase deposition method. The prepared Eu3+ doped Gd2O3 nanotubes were characterized by means of x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy, fourier transform infrared sepctroscopy and thermogravimetry and differential thermal analysis. XRD patterns conrm the cubic phase of Eu3+ doped Gd2O3 nanotubes. From the measured SEM images, the average diameter of the Eu3+: Gd2O3 nanotubes were estimated to be in the range of 50–70 nm. The photoluminescence analysis revealed that the Eu3+: Gd2O3 nanotubes can display a strong red emission peak at around 616 nm, due to the 5D0→7F2 electric dipole transition of Eu3+ ions. Such luminescent powders are expected to find potential applications in fluorescent lamps and display device applications.