Modular Micro Raman Reader Instrument for Fast SERS-Based Detection of Biomarkers

Sensitive detection of biomarkers is very critical in the diagnosis, management, and monitoring of diseases. Recent efforts have suggested that bioassays using surface-enhanced Raman scattering as a signal read-out strategy possess certain unique beneficial features in terms of sensitivity and low limits of detection which set this method apart from its counterparts such as fluorescence, phosphorescence, and radiolabeling. Surface-enhanced Raman scattering (SERS) has also emerged as an ideal choice for the development of multiplexed bioassays. Such promising features have prompted the need for the development of SERS-based tools suitable for point-of-care applications. These tools must be easy to use, portable, and automated for the screening of many samples in clinical settings if diagnostic applications are considered. The availability of such tools will result in faster and more reliable detection of disease biomarkers, improving the accessibility of point-of-care diagnostics. In this paper, we describe a modular Raman reader instrument designed to create such a portable device suitable for screening a large number of samples with minimal operator assistance. The device’s hardware is mostly built with commercially available components using our unique design. Dedicated software was created to automatically run sample screening and analyze the data measured. The mRR is an imaging system specifically created to automate measurements, eliminating human bias while enhancing the rate of data collection and analysis ~2000 times. This paper presents both the design and capabilities of the custom-built modular Raman reader system (mRR) capable of automated and fast measurements of sandwich immunoassay samples on gold substrates using modified gold nanoparticles as Raman tags. The limit of detection (LOD) of the tested MUC4-specific iSERS assay was measured to be 0.41 µg/mL

Test scores, noncognitive skills and economic growth

Many studies have found a strong association between economic outcomes of nations and their performance on international cognitive tests. This association is often interpreted as evidence for the importance of cognitive skills for economic growth. However, noncognitive skills also affect performance on cognitive tests. Following Borghans and Schils (2012), we exploit exogenous variation in the ordering of questions asked by the Programme for International Student Assessment (PISA) to decompose student performance into two components: the starting performance and the decline in performance during the test. The latter component is interpreted as a measure of noncognitive skills. Students from different countries exhibit differences in performance at the start of the test and in their rates of deterioration in performance during the test. Both components have a positive and statistically significant association with economic growth, and the estimated effects are quite similar and robust. Our results show that noncognitive skills are also important for the relationship between test scores and economic growth