Horst Pick

Related publications (63)

Print-Light-Synthesis of Gold Thin Film Electrodes for Electrochemical Sensing

Andreas Stephan Lesch, Horst Pick

The one-step fabrication of gold films by inkjet printing of a gold precursor ink and its photochemical reduction by exposure to UV light is presented. Inkjet printing creates on a substrate with high control micrometer-thin reaction volumes in which upon direct high-intensity light irradiation, the gold precursor reduces to pure and well-adhered Au particles, while all other ink components escape in the gas phase, without the need for any further post-treatment. The Au precursor ink does neither contain stabilizing agents, such as polymers or surfactants, nor sacrificial compounds, such as photoinitiators, to initiate and accelerate the reduction. This economic and green process is known as Print-Light-Synthesis (PLS) and is herein used to create gold patterns of thin compact Au films and separated Au nanoparticles. Gold loadings are in the mu g cm(-2) range and precisely controlled, thanks to the inkjet printing parameters. The gold films are characterized by spectroscopic and electrochemical methods. Finally, the applicability of Au films as electrochemical sensors is demonstrated for the detection of 1,4-butanediol in comparison to a commercial screen-printed Au electrode. The PLS Au electrode shows a 20 times higher sensitivity and opens new possibilities for disposable electrode production.

2023

Effective removal of the rotifer Brachionus calyciflorus from a Chlorella vulgaris microalgal culture by homogeneous solar photo-Fenton at neutral pH

Jiahua Chen, Jérémie Decker, Stefanos Giannakis, Christian Ludwig, Horst Pick, Adrian Pulgarin, Dominik Refardt

In this study, a citrate-modified photo-Fenton process was successfully applied to decontaminate a Chlorella vulgaris microalgae culture spiked with the rotifer Brachionus calyciflorus (5 individuals mL−1). The applied treatment (1 mg L−1 Fe2+, 20 mg L−1 H2O2, 17.5 mg L−1 citric acid) had only moderate effects on viability and regrowth of the microalgae since, after a short post-treatment delay of a few days, they reached final cell densities similar to that obtained for microalgae cultures that were not spiked. The decontamination was effective as no regrowth of rotifers was observed in the microalgae cultures after treatment. The efficacy of the citrate-modified photo-Fenton treatment was also studied with a higher starting concentration of 20 rotifers mL−1 and was compared with a solar light/H2O2 treatment. Results show that both treatments had similar efficacies on the rotifer elimination, but that the citrate-modified photo-Fenton treatment had a lower negative impact on the regrowth of microalgae than the solar light/H2O2 treatment. However, when microalgae cultures were spiked with 20 rotifers mL−1, rotifers were only partially inactivated and post-treatment regrowth occurred, which highlights the importance to apply the photo-Fenton process at an early stage of a contamination to achieve full rotifer elimination. In any case, a contamination with 5 rotifers mL−1 is already a significant threat as numbers above 1000 rotifers mL−1 were reached after 14 days and caused the microalgae culture to fail. Overall, our treatment suggests that the citrate-modified solar photo-Fenton process is an environmentally friendly solution to support the maintenance of contaminant-free microalgal cultures.

2022

Algal cellulose, production and potential use in plastics: Challenges and opportunities

Tobias Borgmeyer, Christian Ludwig, Horst Pick, Adrian Pulgarin, Enio Daniel Zanchetta

The development of new biodegradable plastic materials from renewable sources is a major challenge for plastic industries to provide sustainable alternatives to petroleum plastic. Bio-based plastics are generally obtained from photosynthetic biomass such as higher plants, crops and more recently algae. This review aims to summarise the current state of bioplastic production in general with particular emphasis on algal cellulose and its derivatives (nanocellulose) for bioplastic applications. Despite the potential of algae as a feedstock for nanocellulose, little information is available on strain selection regarding cellulose content and downstream processing. This study lists possible optimization opportunities to increase the cellulose yield of algal biomass and the current status of its conversion to nanocellulose. Moreover, the findings of this review provide insight into existing knowledge and future direction in the algal cellulosic bioplastic domain based on algal bioplastic life cycle assessment studies. Finally, the review gives an overview of the main standards used for biodegradability certifications in view to limit the access to the biodegradable label when the required quality is not reached.

2021

Rapid Noninvasive Skin Monitoring by Surface Mass Recording and Data Learning

Natalia Gasilova, Hubert Girault, Milica Jovic, Andreas Stephan Lesch, Tzu-En Lin, Horst Pick, Yingdi Zhu

Skin problems are often overlooked due to a lack of robust and patient-friendly monitoring tools. Herein, we report a rapid, noninvasive, and high-throughput analytical chemical methodology, aiming at real-time monitoring of skin conditions and early detection of skin disorders. Within this methodology, adhesive sampling and laser desorption ionization mass spectrometry are coordinated to record skin surface molecular mass in minutes. Automated result interpretation is achieved by data learning, using similarity scoring and machine learning algorithms. Feasibility of the methodology has been demonstrated after testing a total of 117 healthy, benign-disordered, or malignant-disordered skins. Remarkably, skin malignancy, using melanoma as a proof of concept, was detected with 100% accuracy already at early stages when the lesions were submillimeter-sized, far beyond the detection limit of most existing noninvasive diagnosis tools. Moreover, the malignancy development over time has also been monitored successfully, showing the potential to predict skin disorder progression. Capable of detecting skin alterations at the molecular level in a nonsurgical and time-saving manner, this analytical chemistry platform is promising to build personalized skin care.

2021

Soft-probe-scanning electrochemical microscopy reveals electrochemical surface reactivity of E. coli biofilms

Sorour Darvishi, Hubert Girault, Andreas Stephan Lesch, Emadeddin Oveisi, Horst Pick

Investigating and understanding dynamic biofilm growth mechanisms is challenging, often because state-of-theart optical characterization tools provide limited information. Micrometric electrochemical imaging of Escherichia coli biofilms using Soft-Probe-Scanning Electrochemical Microscopy (Soft-Probe-SECM) is herein presented as a complementary technique. A soft microelectrode is scanned over biofilms in a gentle contact mode, which is essential to provide a constant working distance. The on-film reduction of an electro-active compound, here the oxidized form of ferrocene methanol, is used to create in situ biofilm metabolic activity maps by applying the feedback mode of SECM. SECM approach curves of identically grown biofilms suggest that the SECM-based detection of metabolic activity is surface-confined. The analysis could therefore be carried out on entire biofilms as well as on tape-stripped biofilm surface layers. The method is further capable of distinguishing between biofilms containing E. coli cells either with or without ampicillin-resistance. Finally, the SECM detection of the degradation of an E. coli biofilm in the presence of different gentamicin concentrations is presented.

2021

Soft-probe-scanning electrochemical microscopy reveals electrochemical surface reactivity of E. coli biofilms

Sorour Darvishi, Hubert Girault, Andreas Stephan Lesch, Emadeddin Oveisi, Horst Pick

Investigating and understanding dynamic biofilm growth mechanisms is challenging, often because state-of-the-art optical characterization tools provide limited information. Micrometric electrochemical imaging of Escherichia coli biofilms using Soft-Probe-Scanning Electrochemical Microscopy (Soft-Probe-SECM) is herein presented as a complementary technique. A soft microelectrode is scanned over biofilms in a gentle contact mode, which is essential to provide a constant working distance. The on-film reduction of an electro-active compound, here the oxidized form of ferrocene methanol, is used to create in situ biofilm metabolic activity maps by applying the feedback mode of SECM. SECM approach curves of identically grown biofilms suggest that the SECM-based detection of metabolic activity is surface-confined. The analysis could therefore be carried out on entire biofilms as well as on tape-stripped biofilm surface layers. The method is further capable of distinguishing between biofilms containing E. coli cells either with or without ampicillin-resistance. Finally, the SECM detection of the degradation of an E. coli biofilm in the presence of different gentamicin concentrations is presented.

2021

Highly Loaded Mildly Edge‐Oxidized Graphene Nanosheet Dispersions for Large‐Scale Inkjet Printing of Electrochemical Sensors

Victor Costa Bassetto, Hubert Girault, Milica Jovic, Andreas Stephan Lesch, Bhawna Nagar, Horst Pick, Yingdi Zhu

Inkjet printing of electrochemical sensors using a highly loaded mildly edge‐oxidized graphene nanosheet (EOGN) ink is presented. An ink with 30 mg/mL EOGNs is formulated in a mixture of N‐methyl pyrrolidone and propylene glycol with only 30 min of sonication. The absence of additives, such as polymeric stabilizers or surfactants, circumvents reduced electrochemical activity of coated particles and avoids harsh post‐printing conditions for additive removal. A single light pulse from a xenon flash lamp dries the printed EGON film within a fraction of a second and creates a compact electrode surface. An accurate coverage with only 30.4 μg of EOGNs per printed layer and cm2 is achieved. The EOGN films adhere well to flexible polyimide substrates in aqueous solution. Electrochemical measurements were performed using cyclic voltammetry and differential pulse voltammetry. An all inkjet‐printed three‐electrode living bacterial cell detector is prepared with EOGN working and counter electrodes and silver‐based quasi‐reference electrode. The presence of E. coli in liquid samples is recorded with four electroactive metabolic activity indicators.

2020

Skin cell analysis

Hubert Girault, Milica Jovic, Andreas Stephan Lesch, Tzu-En Lin, Horst Pick, Yingdi Zhu

The present invention describes an adhesive tape stripping transfer method for quick and non-invasive diagnosis of skin diseases by MALDI-TOF mass spectrometry analysis. Cells from the epidermis layer of a suspicious skin area of a patient are collected using adhesive tapes via at least one application of tape stripping procedure. The adhesive tapes carrying collected skin cells are analyzed directly with MALDI-TOF MS without any sample pretreatment like cell lysis or preparatory cellular component extraction. Detection and diagnosis of human and mouse melanoma are illustrated as examples in the present invention.

2020

Computational modeling of the olfactory receptor Olfr73 suggests a molecular basis for low potency of olfactory receptor-activating compounds

Marc Brugarolas Campillos, Thamani Dahoun, Horst Pick, Horst Vogel, Shuguang Yuan

The mammalian olfactory system uses hundreds of specialized G-protein-coupled olfactory receptors (ORs) to discriminate a nearly unlimited number of odorants. Cognate agonists of most ORs have not yet been identified and potential non-olfactory processes mediated by ORs are unknown. Here, we used molecular modeling, fingerprint interaction analysis and molecular dynamics simulations to show that the binding pocket of the prototypical olfactory receptor Olfr73 is smaller, but more flexible, than binding pockets of typical non-olfactory G-protein-coupled receptors. We extended our modeling to virtual screening of a library of 1.6 million compounds against Olfr73. Our screen predicted 25 Olfr73 agonists beyond traditional odorants, of which 17 compounds, some with therapeutic potential, were validated in cell-based assays. Our modeling suggests a molecular basis for reduced interaction contacts between an odorant and its OR and thus the typical low potency of OR-activating compounds. These results provide a proof-of-principle for identifying novel therapeutic OR agonists.

Springer2019

Detection of bacteria

Hubert Girault, Milica Jovic, Andreas Stephan Lesch, Horst Pick, Yingdi Zhu

A method for bacteria detection and the assessment of the antimicrobial susceptibility profile uses a bacterial viability assay based on combining a highly efficient affinity bacteria enrichment/ separation with an electrochemical redox interrogation measurement. The method comprises: the affinity enrichment/ separation of bacteria from a liquid sample by using ligands-modified paramagnetic or superparamagnetic particles; the subsequent introduction of the bacteria isolate together with a solution containing a metabolic redox marker into a container for incubation; transferring the solution containing the metabolic redox marker and bacteria complexes to an electrochemical cell containing electrodes with magnets outside the reservoir so as to form a bacteria isolate (super)paramagnetic agglutinate on or close to the detection electrode, and the electrochemical detection of the change of the oxidation state of the metabolic redox marker inside the bacteria isolate (super)paramagnetic agglutinate as a direct measure of bacterial metabolic activity. Antimicrobial susceptibility testing (AST) is performed by adding an antibiotic to the sample at any stage, such as before the affinity enrichment/ separation.

2019