In this paper, we report the development of an on-chip aptamer-based fluorescence assay for protein detection and quantification based on sandwich ELISA principles. Thrombin was selected as a model analyte to validate the assay design, which involves two DNA thrombin aptamers recognizing two different epitopes of the protein. Aptamer-functionalized magnetic beads were utilized to capture the target analyte, while a second aptamer, functionalized with quantum dots, was employed for on-chip detection. The binding of thrombin to the two aptamers via sandwich assay was monitored by fluorescence microscopy. The sandwich assay was performed on disposable microfluidic devices, fabricated on double-sided tapes and polymeric materials using a laser cutting approach. The approach enabled rapid thrombin detection with high specificity. Experimental conditions, such as reagent consumption and incubation time, were optimized in the microchip platform for the lowest limit of detection, highest specificity, and shortest assay time. The analytical performance of the microchip based assay was compared to that in the well plate format (generally utilized for ELISA-based methodologies). The results show that microfluidic chip proved to be a rapid and efficient system for aptamer-based thrombin assays, requiring only minimal (microliter) reagent use. This work demonstrated the successful application of on-chip aptamer-based sandwich assays for detection of target proteins of biomedical importance.

Numerous applications of polyethylene glycol derived polymers (PEGs) have been reported in the scientific literature for many years. With increasing experience and comfort by regulatory authorities, worldwide, in the utilization of these materials in drug and medical device applications, their use in a variety of research and development areas is expanding. This review will focus on just the range of applications of PEGs published in the first half of 2014 in the medical device, drug development, and diagnostics areas, including drug delivery, wound healing, cell culture models, and tissue regeneration.

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Mass Spectrometry (MS) has wide applications in many fields, from biology and medicine and from chemistry and food industry. MS has also been successfully applied to the analysis of heavy metals, small molecules or large, polymeric molecules, and this analysis could be performed either by analyzing one molecule at the time or by analyzing simultaneously complex or very complex mixtures. Here we focus on several applications of MS in the analysis of paint, artist's paints, and powder coatings components reported recently in the literature.