Thomas Hirsch

Dr. Thomas Hirsch

Institute of Analytical Chemistry, Chemo- and Biosensors,University of Regensburg, 93053 Regensburg, Germany
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Research Focus & Metrics

Academic Career Length

30Years (1997-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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28 January 2014 in Angewandte Chemie International Edition
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Journal Article
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CFChristoph Fenzl
Christoph Fenzl
Thomas HirschThomas Hirsch
Thomas Hirsch
OWOtto Wolfbeis
Otto Wolfbeis

8 July 2014 in Microchimica Acta
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Journal Article
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BSBankim J. Sanghavi
Bankim J. Sanghavi
OWOtto S. Wolfbeis
Otto S. Wolfbeis
Thomas HirschThomas Hirsch
Thomas Hirsch
NSNathan Swami
Nathan Swami

Abstract

Nanomaterial-modified detection systems represent a chief driver towards the adoption of electrochemical methods, since nanomaterials enable functional tunability, ability to self-assemble, and novel electrical, optical and catalytic properties that emerge at this scale. This results in tremendous gains in terms of sensitivity, selectivity and versatility. We review the electrochemical methods and mechanisms that may be applied to the detection of neurological drugs. We focus on understanding how specific nano-sized modifiers may be applied to influence the electron transfer event to result in gains in sensitivity, selectivity and versatility of the detection system. This critical review is structured on the basis of the Anatomical Therapeutic Chemical (ATC) Classification System, specifically ATC Code N (neurotransmitters). Specific sections are dedicated to the widely used electrodes based on the carbon materials, supporting electrolytes, and on electrochemical detection paradigms for neurological drugs and neurotransmitters within the groups referred to as ATC codes N01 to N07. We finally discuss emerging trends and future challenges such as the development of strategies for simultaneous detection of multiple targets with high spatial and temporal resolutions, the integration of microfluidic strategies for selective and localized analyte pre-concentration, the real-time monitoring of neurotransmitter secretions from active cell cultures under electro- and chemotactic cues, aptamer-based biosensors, and the miniaturization of the sensing system for detection in small sample volumes and for enabling cost savings due to manufacturing scale-up. The Electronic Supporting Material (ESM) includes review articles dealing with the review topic in last 40 years, as well as key properties of the analytes, viz., pKa values, half-life of drugs and their electrochemical mechanisms. The ESM also defines analytical figures of merit of the drugs and neurotransmitters. The article contains 198 references in the main manuscript and 207 references in the Electronic Supporting Material.

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1 December 2014 in Nanoscale
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SWStefan Wilhelm
Stefan Wilhelm
MKMartin Kaiser
Martin Kaiser
CWChristian Würth
Christian Würth
JHJosef Heiland
Josef Heiland
Carolina Carrillo-CarriónCarolina Carrillo-Carrión
Carolina Carrillo-Carrión
Thomas HirschThomas Hirsch
Thomas Hirsch
We present a systematic study on the effect of surface ligands on the luminescence properties and colloidal stability of β-NaYF4:Yb3+,Er3+ upconversion nanoparticles (UCNPs), comparing nine different surface coatings to render these UCNPs water-dispersible and bioconjugatable. A prerequisite for this study was a large-scale synthetic method that yields ∼2 g per batch of monodisperse oleate-capped UCNPs providing identical core particles. These ∼23 nm sized UCNPs display an upconversion quantum yield of ∼0.35% when dispersed in cyclohexane and excited with a power density of 150 W cm−2, underlining their high quality. A comparison of the colloidal stability and luminescence properties of these UCNPs, subsequently surface modified with ligand exchange or encapsulation protocols, revealed that the ratio of the green (545 nm) and red (658 nm) emission bands determined at a constant excitation power density clearly depends on the surface chemistry. Modifications relying on the deposition of additional (amphiphilic) layer coatings, where the initial oleate coating is retained, show reduced non-radiative quenching by water as compared to UCNPs that are rendered water-dispersible via ligand exchange. Moreover, we could demonstrate that the brightness of the upconversion luminescence of the UCNPs is strongly affected by the type of surface modification, i.e., ligand exchange or encapsulation, yet hardly by the chemical nature of the ligand.

27 October 2014 in Accounts of Chemical Research
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Journal Article
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VMVerena Muhr
Verena Muhr
SWStefan Wilhelm
Stefan Wilhelm
Thomas HirschThomas Hirsch
Thomas Hirsch
OWOtto Wolfbeis
Otto Wolfbeis

1 May 2017 in ACS Sensors
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Journal Article
Closed access
CFChristoph Fenzl
Christoph Fenzl
PNPranati Nayak
Pranati Nayak
Thomas HirschThomas Hirsch
Thomas Hirsch
OWOtto Wolfbeis
Otto Wolfbeis
HAHusam N. Alshareef
Husam N. Alshareef
ABAntje J. Baeumner
Antje J. Baeumner

1 October 2012 in TrAC Trends in Analytical Chemistry
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Journal Article
Closed access
SKSven Kochmann
Sven Kochmann
Thomas HirschThomas Hirsch
Thomas Hirsch
OWOtto S. Wolfbeis
Otto S. Wolfbeis