SERS-based immunoassay using a gold array-embedded gradient microfluidic chip.

Here we report the development of a programmable and fully automatic gold array-embedded gradient microfluidic chip that integrates a gradient microfluidic device with gold-patterned microarray wells. This device provides a convenient and reproducible surface-enhanced Raman scattering (SERS)-based immunoassay platform for cancer biomarkers. We used hollow gold nanospheres (HGNs) as SERS agents because of their highly sensitive and reproducible characteristics.

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.

Surface-enhanced Raman scattering imaging of HER2 cancer markers overexpressed in single MCF7 cells using antibody conjugated hollow gold nanospheres.

Antibody-conjugated hollow gold nanospheres (HGNs) have been used for the SERS imaging of HER2 cancer markers overexpressed in single MCF7 cells. SERS mapping images show that HGNs have much better homogeneous scattering properties than silver nanoparticles. The results demonstrate the potential feasibility of HGNs as highly sensitive and homogeneous sensing probes for biological imaging of cancer markers in live cells.

DNA hybridization detection in a microfluidic channel using two fluorescently labelled nucleic acid probes.

A conceptually new technique for fast DNA detection has been developed. Here, we report a fast and sensitive online fluorescence resonance energy transfer (FRET) detection technique for label-free target DNA. This method is based on changes in the FRET signal resulting from the sequence-specific hybridization between two fluorescently labelled nucleic acid probes and target DNA in a PDMS microfluidic channel.

Development of an open sandwich fluoroimmunoassay based on fluorescence resonance energy transfer.

We have developed a sensitive, one-step, homogeneous open sandwich fluoroimmunoassay (OsFIA) based on fluorescence resonance energy transfer (FRET) and luminescent semiconductor quantum dots (QDs). In this FRET assay, estrogen receptor beta (ER-beta) antigen was incubated with QD-labeled anti-ER-beta monoclonal antibody and Alexa Fluor (AF)-labeled anti-ER polyclonal antibody for 30 min, followed by FRET measurement. The dye separation distance was estimated between 80 and 90 A.

Analysis of passive mixing behavior in a poly(dimethylsiloxane) microfluidic channel using confocal fluorescence and Raman microscopy.

Confocal fluorescence microscopy (CFM) and confocal Raman microscopy (CRM) have been applied to monitor the laminar flow mixing behavior in a poly(dimethylsiloxane) (PDMS) microfluidic channel. Two passive PDMS micromixing devices were fabricated for this purpose: a two-dimensional round-wave channel and a three-dimensional serpentine channel. The microscale laminar flow mixing of ethanol and isopropanol was evaluated using the CFM and CRM at various flow rates.

Enhancement of the protein loading density by a pre-cleaning process of a gold substrate: confocal laser scanning microscopic study.

The immobilization of glucose oxidase (GOx), using self assembled monolayers (SAMs) on gold surfaces, was investigated by grazing angle FT-IR spectroscopy, surface plasmon resonance (SPR) spectroscopy, and atomic force microscopy (AFM) in conjunction with confocal laser scanning microscopy (CLSM). To find an optimum condition for the maximum GOx loading density on gold surfaces, different cleaning protocols were examined. The loading density of GOx on surfaces was investigated by AFM and CLSM.