Soo Ik Chang

Highly reproducible immunoassay of cancer markers on a gold-patterned microarray chip using surface-enhanced Raman scattering imaging

This paper reports a highly reproducible immunoassay of cancer markers using surface-enhanced Raman scattering (SERS) imaging. SERS is a highly sensitive detection method but it is limited in its ability to achieve reproducible signal enhancement because of the difficulty with precisely controlling the uniform distribution of hot junctions. Consequently, inconsistent enhancement prevents the wide exploitation of SERS detection as a bio-detection tool for quantitative analysis. To resolve this problem, we explored the use of a SERS imaging-based immunoassay. For this purpose, Raman reporter-labeled hollow gold nanospheres (HGNs), were manufactured and antibodies were immobilized onto their surfaces for targeting specific antigens. After the formation of sandwich immunocomplexes using these functional HGNs on the surfaces of gold patterned wells, the SERS mapping images were measured. For target protein markers, 12×9 pixels were imaged using a Raman mapping technique in the 0-10(-4) g/mL concentration range, and the SERS signals for 66 pixels were averaged. Here, the SERS imaging-based assay shows much better correlations between concentration and intensity than does the conventional point-based assay. The limits of detection were determined to be 0.1 pg/mL and 1.0 pg/mL for angiogenin (ANG) and alpha-fetoprotein (AFP), respectively. This detection sensitivity is increased by three or four orders of magnitude over that of conventional ELISA method. The detectable dynamic range for SERS imaging (10(-4)-10(-12) g/mL) is also much wider than that for ELISA (10(-6)-10(-9) g/mL).

Simultaneous immunoassay for the detection of two lung cancer markers using functionalized SERS nanoprobes.

A quick and reproducible SERS-based immunoassay, using functionalized hollow gold nanospheres and magnetic beads, has been developed. Here, a simultaneous detection of dual cancer markers in blood serum has been achieved under a single excitation wavelength. The accuracy and sensitivity for clinical sera from five patients confirms their diagnostic feasibility.

Inhibitory effect of salmosin, a Korean snake venomderived disintegrin, on the integrin αv-mediated proliferation of SK-Mel-2 human melanoma cells

We have investigated the inhibitory effect of salmosin on integrin‐mediated human tumour cell proliferation. SK‐Mel‐2 human melanoma cell adhesion to denatured collagen or vitronectin was found to be significantly and statistically inhibited by salmosin in a dose‐dependent manner (P < 0.05). Moreover, the binding of SK‐Mel‐2 cells to salmosin‐coated plates was specifically disrupted by anti‐integrin αv monoclonal antibody at 8αg mL−1, but not by anti‐integrin monoclonal antibody. These findings indicated that salmosin inhibited the adhesion of SK‐Mel‐2 cells to denatured collagen by specifically blocking integrin αv. The proliferation of SK‐Mel‐2 cells on a denatured collagen‐coated plate was statistically and significantly inhibited by salmosin induced apoptosis in a dose‐dependent manner (P < 0.05). Anti‐integrin αv monoclonal antibody, anti‐integrin αvβ3 monoclonal antibody, and synthetic RGD peptide also suppressed SK‐Mel‐2 cell proliferation. Several lines of experimental evidence strongly suggested that the inhibition of SK‐Mel‐2 cell proliferation by salmosin was due to the induction of apoptosis via the blocking of integrin αv‐mediated cell survival.

The inhibitory effects of recombinant plasminogen kringle 1-3 on the neovascularization of rabbit cornea induced by angiogenin, bFGF, and VEGF

Angiostatin is a potent angiogenesis inhibitor that is composed of the first four kringles of plasminogen fragment. Angiostatin with one less kringle molecule (kringle 1 to 3) was recently demonstrated to be an effective angiogenic inhibitor. To determine whether recombinant plasminogen kringle 1-3 (rPK1-3) can inhibit the corneal neovascularization induced by potent angiogenic factors; angiogenin, bFGF, or VEGF, hydron polymer discs each containing 2.0 µg of angiogenin, 500 ng of bFGF, or 500 ng of VEGF respectively were implanted into the corneal stroma of 138 rabbit eyes, and then discs each containing 10 µg, 12.5 µg, 20 µg or 30 µg of rPK1-3 were implanted randomly. Discs containing phosphate buffered saline were also implanted as a control. The angiogenesis score on number and length of newly formed vessels on the each of the rabbits cornea were recorded daily by two observers (blinded). The treated corneas were also examined histologically. Recombinant PK1-3 treated corneas showed less neovascularization induced by all angiogenic factors (p < 0.05). and the extent of inhibition of neovascularization was proportional to the concentration of rPK1-3 (p < 0.05). Histologic examination showed leukocyte infiltration into the corneal stroma on the PBS treated eyes whereas rPK1-3 treated eyes showed only traces of leukocytes. These results of the effective rPK1-3 inhibition of corneal neovascularization induced by angiogenin, bFGF, or VEGF suggest that this angiostatin related fragment, rPK1-3, may be useful in the treatment of various neovascular diseases.