3 results
Search Results
2. Paper-based assay of antioxidant activity using analyte-mediated on-paper nucleation of gold nanoparticles as colorimetric probes
- Author
-
Foteini A. Kappi, Tatiana G. Choleva, Athanasios G. Vlessidis, and Dimosthenis L. Giokas
- Subjects
Paper ,Analyte ,Antioxidant ,Surface Properties ,medicine.medical_treatment ,Nucleation ,Nanoparticle ,Wine ,Nanotechnology ,Biochemistry ,Antioxidants ,Analytical Chemistry ,Nanomaterials ,medicine ,Environmental Chemistry ,Electrodes ,Spectroscopy ,Detection limit ,Tea ,Chemistry ,Linear range ,Colloidal gold ,Nanoparticles ,Colorimetry ,Gold ,Biological system - Abstract
With the increasing interest in the health benefits arising from the consumption of dietary products rich in antioxidants, there exists a clear demand for easy-to-use and cost-effective tests that can be used for the identification of the antioxidant power of food products. Paper-based analytical devices constitute a remarkable platform for such expedient and low-cost assays with minimal external resources but efforts in this direction are still scarce. In this work we introduce a new paper-based device in the form of a sensor patch that enables the determination of antioxidant activity through analyte-driven on-paper formation of gold nanoparticles. The principle of detection capitalizes, for the first time, on the on-paper nucleation of gold ions to its respective nanoparticles, upon reduction by antioxidant compounds present in an aqueous sample. The ensuing chromatic transitions, induced on the paper surface, are used as an optical "signature" of the antioxidant strength of the solution. The response of the paper-based sensor was evaluated against a large variety of antioxidant species and the respective dose response curves were constructed. On the basis of these data, the contribution of each species according to its chemical structure was elucidated. For the analysis of real samples, a concentration-dependent colorimetric response was established against Gallic acid equivalents over a linear range of 10 μM-1.0 mM, with detection limits at the low and ultra-low μM levels (i.e.
- Published
- 2015
3. The cooperation of enamelin and amelogenin in controlling octacalcium phosphate crystal morphology
- Author
-
Fan, Daming, Iijima, Mayumi, Bromley, Keith M, Yang, Xiudong, Mathew, Shibi, Moradian-Oldak, Janet, Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, Calif. , USA, and Dental Materials Science, Asahi University School of Dentistry, Gifu, Japan
- Subjects
Calcium Phosphates ,Paper ,Circular dichroism ,Histology ,Sus scrofa ,Nucleation ,Mineralogy ,Fluorescence spectroscopy ,Biophysical Phenomena ,chemistry.chemical_compound ,Dynamic light scattering ,stomatognathic system ,Dental Enamel Proteins ,Animals ,Computer Simulation ,Octacalcium phosphate ,Enamel paint ,Amelogenin ,Molecular Weight ,chemistry ,visual_art ,visual_art.visual_art_medium ,Biophysics ,Anatomy ,Crystallization ,Macromolecule ,Protein Binding - Abstract
Enamel matrix proteins, including the most abundant amelogenin and lesser amounts of enamelin, ameloblastin, and proteinases, play vital roles in controlling crystal nucleation and growth during enamel formation. The cooperative action between amelogenin and the 32-kDa enamelin is critical to regulating the growth morphology of octacalcium phosphate crystals. Using biophysical methods, we investigated the interaction between the 32-kDa enamelin and recombinant pig amelogenin 148 (rP148) at pH 6.5 in phosphate-buffered saline (PBS). Dynamic light scattering results showed a trend of increasing particle size in the mixture with the addition of enamelin to amelogenin. Upon addition of the 32-kDa enamelin, the shift and intensity decrease in the ellipticity minima of rP148 in the circular dichroism spectra of rP148 illustrated a direct interaction between the 2 proteins. In the fluorescence spectra, the maximum emission of rP148 was blue shifted from 335 to 333 nm in the presence of enamelin as a result of complexation of the 2 proteins. Our results demonstrate that the 32-kDa enamelin has a close association with amelogenin at pH 6.5 in PBS buffer. Our present study provides novel insights into the possible cooperation between enamelin and amelogenin in macromolecular coassembly and in controlling enamel mineral formation
- Published
- 2011
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.