This paper describes the modification of microfluidic paper-based analytical devices (μPADs) with chitosan to improve the analytical performance of colorimetric measurements associated with enzymatic bioassays. Chitosan is a natural biopolymer extensively used to modify biosensing surfaces due to its capability of providing a suitable microenvironment for the direct electron transfer between an...

We report the enhancement of the colorimetric response of horseradish peroxidase (HRP) and alkaline phosphatase (AP) in bioassays by thermally evaporated silver, gold, copper and nickel thin films. In this regard, a model bioassay based on biotin-avidin interactions was employed. Biotin groups and enzymes were introduced to all surfaces using a biotinylated linker molecule and avidin, respectiv...

Background Abnormalities in brain cholesterol homeostasis have been reported in Huntington's disease (HD), an adult-onset neurodegenerative disorder caused by an expansion in the number of CAG repeats in the huntingtin (HTT) gene. However, the results have been contradictory with respect to whether cholesterol levels increase or decrease in HD models. Biochemical and mass spectrometry methods s...

Cellulose-paper-based colorimetric bioassays may be used at the point of sampling without sophisticated equipment. This study reports the development of a colorimetric bioassay based on cellulose that can detect pathogen DNA. The detection was based on covalently attached single-stranded DNA probes and visual analysis. A cellulose surface functionalized with tosyl groups was prepared by the N,N...

28 29 Sepsis is a medical emergency demanding early diagnosis and tailored antimicrobial therapy. 30 Every hour of delay in effective therapy measurably increases mortality. Blood culture is currently the 31 reference standard for diagnosing bloodstream infection, a multistep process which may take one to 32 several days. Here, we report a novel paradigm for earlier detection and simultaneous i...

A novel colorimetric assay employing oligonucleotide-conjugated gold nanoparticle (AuNP probes) and rolling circle amplification (RCA) was developed for simple detection of mercuric ions (Hg2+). The thymine-Hg2+-thymine (T-Hg2+-T) coordination chemistry makes our detection system selective for Hg2+. In the presence of Hg2+, the thymine 12-mer oligonucleotide is unable to act as a primer for RCA...