Bagal-Kestwal D.Kestwal R.M.Chiang B.-H.2019-07-112019-07-11201514773155https://scholars.lib.ntu.edu.tw/handle/123456789/413279In the present study, invertase-mediated nanogold clusters were synthesized on onion membranes, and their application for sucrose biosensor fabrication was investigated. Transmission electron microscopy revealed free nanoparticles of various sizes (diameter ~5 to 50 nm) along with clusters of nanogold (~95 to 200 nm) on the surface of inner epidermal membranes of onions (Allium cepa L.). Most of the polydispersed nanoparticles were spherical, although some were square shaped, triangular, hexagonal or rod-shaped. Ultraviolet-visible spectrophotometric observations showed the characteristic peak for nanoparticles decorated invertase-onion membrane at approximately 301 nm. When excited at 320 nm in the presence of sucrose, the membranes exhibited a photoemission peak at 348 nm. The fluorescence lifetime of this nanogold modified onion membrane was 6.20 ns, compared to 2.47 ns for invertase-onion membrane without nanogold. Therefore, a sucrose detection scheme comprised of an invertase/nanogold decorated onion membrane was successfully developed. This fluorescent nanogold-embedded onion membrane drop-test sensor exhibited wide acidic to neutral working pH range (4.0-7.0) with a response time 30 seconds (<1 min). The fabricated quenching-based probe had a low detection limit (2x10-9 M) with a linear dynamic range of 2.25x10-9 to 4.25x10-8 M for sensing sucrose. A microplate designed with an enzyme-nanomaterial-based sensor platform exhibited a high compliance, with acceptable percentage error for the detection of sucrose in green tea samples in comparison to a traditional method. With some further, modifications, this fabricated enzyme-nanogold onion membrane sensor probe could be used to estimate glucose concentrations for a variety of analytical samples.Graphical abstract Synthesis and characterization of invertase assisted nanogold clusters on onion membranes and their application for fluorescence-based sucrose sensor. ? Bagal-Kestwal et al.; licensee BioMed Central.AnalyteFluorescenceGlucoseGold nanoparticlesInvertaseNanogold clustersOnion membraneQuenching-based biosensorSucrosejournal article10.1186/s12951-015-0089-1https://www.scopus.com/inward/record.uri?eid=2-s2.0-84928552205&doi=10.1186%2fs12951-015-0089-1&partnerID=40&md5=8bda556096b4a847eee287a4978fc6472-s2.0-84928552205https://www.scopus.com/inward/record.uri?eid=2-s2.0-84928552205&doi=10.1186%2fs12951-015-0089-1&partnerID=40&md5=8bda556096b4a847eee287a4978fc647