title: Fabrication of Nanostructured Mesoporous Germanium for Application in Laser Desorption Ionization Mass Spectrometry.
abstract: Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is a high-throughput analytical technique ideally suited for small-molecule detection from different bodily fluids (e.g., saliva, urine, and blood plasma). Many SALDI-MS substrates require complex fabrication processes and further surface modifications. Furthermore, some substrates show instability upon exposure to ambient conditions and need to be kept under special inert conditions. We have successfully optimized mesoporous germanium (meso-pGe) using bipolar electrochemical etching and efficiently applied meso-pGe as a SALDI-MS substrate for the detection of illicit drugs such as in the context of workplace, roadside, and antiaddictive drug compliance. Argon plasma treatment improved the meso-pGe efficiency as a SALDI-MS substrate and eliminated the need for surface functionalization. The resulting substrate showed a precise surface geometry tuning by altering the etching parameters, and an outstanding performance for illicit drug detection with a limit of detection in Milli-Q water of 1.7 ng/mL and in spiked saliva as low as 5.3 ng/mL for cocaine. The meso-pGe substrate had a demonstrated stability over 56 days stored in ambient conditions. This proof-of-principle study demonstrates that meso-pGe can be reproducibly fabricated and applied as an analytical SALDI-MS substrate which opens the door for further analytical and forensic high-throughput applications.
authors.affiliation: Future Industries Institute, University of South Australia , University Boulevard, Mawson Lakes, Adelaide, 5095 South Australia, Australia.|ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Future Industries Institute, University of South Australia , GPO Box 2471, Adelaide, South Australia 5001, Australia.
authors.forename: Hazem H
authors.identifier: http://orcid.org/0000-0002-2107-9761
authors.initials: HH
authors.lastname: Abdelmaksoud
authors.affiliation: Future Industries Institute, University of South Australia , University Boulevard, Mawson Lakes, Adelaide, 5095 South Australia, Australia.
authors.forename: Taryn M
authors.initials: TM
authors.lastname: Guinan
authors.affiliation: Future Industries Institute, University of South Australia , University Boulevard, Mawson Lakes, Adelaide, 5095 South Australia, Australia.|ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Future Industries Institute, University of South Australia , GPO Box 2471, Adelaide, South Australia 5001, Australia.
authors.forename: Nicolas H
authors.identifier: http://orcid.org/0000-0002-1536-7804
authors.initials: NH
authors.lastname: Voelcker
mesh_terms: D005857:Germanium; D007834:Lasers; D049329:Nanostructures; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D015813:Substance Abuse Detection
chemical_list: D005857:Germanium
keywords: SALDI-MS; bipolar electrochemical etching; cocaine; germanium; illicit drugs; laser desorption ionization; mesoporous germanium