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The conventional tissue biopsy method yields isolated snapshots of a narrow region. Therefore, it cannot facilitate comprehensive disease characterization and monitoring. Recently, the detection of tumor-derived components in body fluids─a practice known as liquid biopsy─has attracted increased attention from the biochemical research and clinical application viewpoints. In this vein, surface-enhanced Raman scattering (SERS) has been identified as one of the most powerful liquid-biopsy analysis techniques, owing to its high sensitivity and specificity. Moreover, it affords high-capacity spectral multiplexing for simultaneous target detection and a unique ability to obtain intrinsic biomolecule-fingerprint spectra. This paper presents the fabrication of silver nanosnowflakes (SNSFs) using the polyol method and their subsequent dropping onto a hydrophobic filter paper. The SERS substrate, which comprises the SNSFs and hydrophobic filter paper, facilitates the simultaneous detection of creatinine and cortisol in human sweat using a hand-held Raman spectrometer. The proposed SERS system affords Raman spectrometry to be performed on small sample volumes (2 μL) to identify the normal and at-risk creatinine and cortisol groups.

Fully automated system for sample preparation in molecular diagnostics was developed. The small cartridge with multiple chambers and a rotating valve was designed for automated processes such as extraction, separation and purifications during the DNA sample preparation. The automated processes such as injection, mixing, capturing and valve on/off motions were controlled by an affordable, motorized control system. We demonstrated the automated DNA extraction of pathogenic bacteria using this system. The deviations in the purity and real-time polymerase chain reaction (PCR) detection of the automated DNA extraction samples were clearly decreased. The device provided rapid, reliable, and reproducible sample preparation in comparison with manual DNA extraction. This automated platform can be utilized in emergent point-of-care testing of infectious disease and foodborne bacteria.

A novel cartridge-based platform was developed to perform fully automated sample preparation, amplification, and analysis of nucleic acids. The cartridge consists of three layers: multiple reagent chambers, a mixing reservoir, and elutes and waste chambers. The fluidic manipulation and solution mixing inside the cartridge were controlled by motor systems. After loading a sample specimen, each reagent solution in the chambers of the cartridge was sequentially injected into the mixing reservoir. Extracted nucleic acids were captured by magnetic beads and transferred into a small eluates chamber. Automated sample preparation and isothermal amplification of nucleic acids for pathogenic bacteria were demonstrated in this all-in one cartridge platform. This cartridge system provides rapid and reproducible sample preparation in comparison with manual methods. In addition, real-time detection of isothermal amplification using the implemented photometric system was compared with that of using a commercial polymerase chain reaction (PCR) device. This system has the potential to become a more reliable diagnostic tool for fast detection of contagious, foodborne, and emergency point-of-care (POC) diseases.

Cancer biomarkers, an indication of cancer cells in the body, can play an important role in diagnosis, prognosis, and the prediction of treatment efficacy as well as recurrence. Here, we developed a simple Raman spectroscopic method that utilized a silver nanoforest (SNF) substrate and a hand-held Raman spectrometer for identifying cancer protein biomarkers with very high sensitivity. First, various concentrations of ethanol solutions were analyzed using the hand-held Raman spectrometer to confirm its performance. Next, the functionality of the SNF substrate, in other words, the effect of the surface enhanced Raman scattering was characterized by measuring varying, known concentrations of rhodamine 6G. The novel structure of the SNF substrate can provide the enhancement factor of 1.13 × 107. Following the characterization, the Raman spectra of cancer biomarkers, epithelial cell adhesion molecule (EpCAM) and carcinoembryonic antigen (CEA), were examined using the hand-held Raman spectrometer with the SNF substrate. As low as 0.2 picomoles of the protein were successfully detected with very tiny amount of sample solutions (~2 µl) containing cancer biomarkers. The developed technique allows for the simple, convenient measurement of cancer protein biomarkers using the SNF substrate and hand-held Raman spectrometer. We believe these findings will motivate the creation of Raman libraries for cancer biomarkers.