Michael Hirtz

Michael Hirtz
Karlsruhe Institute of Technology | KIT · Institute of Nanotechnology

PD Dr. rer. nat. Dr. rer. medic.

About

149
Publications
31,827
Reads
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2,747
Citations
Citations since 2017
52 Research Items
1679 Citations
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2017201820192020202120222023050100150200250300
2017201820192020202120222023050100150200250300
Introduction
I'm working on surface and device functionalization and the bioactive patterning of surfaces in the micro- to nanoscale utilizing dip-pen nanolithography, polymer pen lithography and related techniques like micro spotting and stamping.
Additional affiliations
March 2014 - April 2014
Northwestern University
Position
  • Guest Scientist
February 2013 - April 2013
Nanyang Technological University
Position
  • Visiting Fellow
January 2010 - present
Karlsruhe Institute of Technology
Position
  • Group Leader
Education
July 2012 - July 2017
Westfälische Wilhelms-Universität Münster
Field of study
  • Physics
June 2005 - October 2009
Westfälische Wilhelms-Universität Münster
Field of study
  • Physics
June 2005 - March 2008
Universitätsklinikum Münster
Field of study
  • Medical Science

Publications

Publications (149)
Article
Full-text available
The application of graphene in sensor devices depends on the ability to appropriately functionalize the pristine graphene. Here we show the direct writing of tailored phospholipid membranes on graphene using dip-pen nanolithography. Phospholipids exhibit higher mobility on graphene compared with the commonly used silicon dioxide substrate, leading...
Article
Full-text available
Despite diverse applications, phospholipid membrane stacks generated by dip-pen nanolithography (DPN) still lack a thorough and systematic characterization that elucidates the whole ink transport process from writing to surface spreading, with the aim of better controlling the resulting feature size and resolution. We report a quantitative analysis...
Article
Surface‐bound microarrays of multiple oligo‐ and macromolecules (e.g., peptides, DNA) offer versatile options in biomedical applications like drug screening, DNA analysis, or medical diagnostics. Combinatorial syntheses of these molecules in situ can save significant resources in regard to processing time and material use. Furthermore, high feature...
Article
Full-text available
Classical microcontact printing and polymer pen lithography (PPL) involve ink transfer to substrates using solid elastomeric stamps. Ink depletion thus limits the number of successive stamping steps without reinking. Porous stamps developed to overcome this limitation are used only for manual proof-of-principle experiments. Here, porous composite s...
Article
Full-text available
The capture of circulating tumor cells (CTCs) is still a challenging application for microfluidic chips, as these cells are rare and hidden in a huge background of blood cells. Here, different microfluidic ceiling designs in regard to their capture efficiency for CTCs in model experiments and more realistic conditions of blood samples spiked with a...
Article
Full-text available
While patterning 2D metallic nanostructures are well established through different techniques, 3D printing still constitutes a major bottleneck on the way to device miniaturization. In this work a fluid phase phospholipid ink is used as a building block for structuring with dip‐pen nanolithography. Following a bioinspired approach that relies on in...
Article
Liquid Metal Electronics In article number 2202987, Michael Hirtz and co‐workers take a close look at gold/liquid metal contacts as they appear, e.g., in flexible electronics. By correlating complementary chemical and morphological characterization techniques, new details on the evolution of such contacts are revealed.
Article
Diamond enables the construction of various (bio)sensors, including those with quantum‐based detection. However, bare diamond interfaces are susceptible to unspecific adhesion of proteins and other macromolecules from biological media or complex samples. This impairs selectivity in biosensing, leads to low signal‐to‐noise ratio in fluorescence‐base...
Article
Liquid metals (LMs) play a growing role in flexible electronics and connected applications. Here, LMs come into direct contact with metal electrodes thus allowing for corrosion and additional alloying, potentially compromising device stability. Nevertheless, comprehensive studies on the interfacial interaction of the materials are still sparse. The...
Article
Nanomaterials-based sensors are a dire need for credible and accurate determination of pesticides in water and food samples as a monitoring tool. Herein, electrocatalysts of Pd and ZnO NPs supported on a highly porous framework of activated carbons (APC) were prepared for efficient electrochemical detection of carbaryl trace. First, activated potat...
Article
Nanomaterials-based sensors are direly needed as a monitoring tool for the credible and accurate determination of pesticides in water and food samples. Herein, electrocatalysts of Pd and ZnO nanoparticles (NPs) supported on a highly porous framework of activated carbons (APC) were prepared for efficient electrochemical detection of carbaryl trace....
Article
Antifouling Polymer Brushes In article number 2102325, Bingquan Yang, Michael Hirtz, and co-workers investigate the efficiency of cyclooctyne click chemistry based patterned immobilization of functional compounds on azide-bearing diblock polymer brushes. Microchannel cantilever spotting (μCS) enables spotting of microarrays on the antifouling brush...
Article
Platelets are cell fragments from megakaryocytes devoid of the cell nucleus. They are highly sensitive and easily activated by nonphysiological surfaces. Activated platelets have an intrinsic mechanism to release various proteins that participate in multiple pathways, initiating the platelet activation cascade. Surface-induced platelet activation i...
Article
Full-text available
We have conceptualized and demonstrated an approach based on the combination of hydrophobicity, a substrate‐independent dip coating as porous material with double residual chemical reactivities for implementing multiplexed, miniaturized and unclonable bulk‐infused patterns of different fluorophores following distinct reaction pathways. The embedded...
Article
Full-text available
Strain‐promoted alkyne‐azide cycloaddition (SPAAC) has become an indispensable tool in bioorthogonal conjugation and surface immobilization. While numerous studies have focused on enhancing the reactivity of cyclooctynes, a facile method to evaluate the binding efficiency for cyclooctyne‐azide‐based immobilization without any sophisticated faciliti...
Article
Patterning double‐reactive porous coatings: A substrate‐independent porous dip coating with dual chemical reactivity enables multiplexed bulk‐infused and unclonable micropatterns of fluorophores attaching by distinct reaction pathways. The hydrophobicity of the coating restricts spreading of aqueous inks and enables miniaturization of patterns with...
Article
Full-text available
Three-dimensional printing at the micro-/nanoscale represents a new challenge in research and development to achieve direct printing down to nanometre-sized objects. Here, FluidFM, a combination of microfluidics with atomic force microscopy, offers attractive options to fabricate hierarchical polymer structures at different scales. However, little...
Article
Full-text available
Biomedical applications such as cell screening or cell–cell interaction studies require placement and adhesion of cells on surfaces with controlled numbers and location. In particular, single-cell arraying and positioning has come into focus as a basis of such applications. An ideal substrate would combine biocompatibility with favorable attributes...
Article
Microstructuring, in particular, the additive functionalization of surfaces with, e.g., conductive or bioactive materials plays a crucial role in many applications in sensing or printed electronics. Mostly, the lithography steps are made prior to assembling functionalized surfaces into the desired places of use within a bigger device as a microflui...
Article
The creation of biologically inspired artificial membranes on substrates with custom size and in close proximity to each other not only provides a platform to study biological processes in a simplified manner, but they also constitute building blocks for chemical or biological sensors integrated in microfluidic devices. Scanning probe lithography t...
Article
Full-text available
Extracellular vesicles (EVs) contain various bioactive molecules such as DNA, RNA, and proteins, and play a key role in the regulation of cancer progression. Furthermore, cancer-associated EVs carry specific biomarkers and can be used in liquid biopsy for cancer detection. However, it is still technically challenging and time consuming to detect or...
Article
Full-text available
The curvature of lipid membranes plays a key role in many relevant biological processes such as membrane trafficking, vesicular budding and host-virus interactions. In vitro studies on the membrane curvature of simplified biomimetic models in the nanometer range are challenging, due to their complicated nanofabrication processes. In this work, we p...
Article
Full-text available
A versatile liquid metal (LM) printing process enabling the fabrication of various fully printed devices such as intra‐ and interconnect wires, resistors, diodes, transistors, and basic circuit elements such as inverters which are process compatible with other digital printing and thin film structuring methods for integration is presented. For this...
Article
Full-text available
Immobilization of functional molecules in ordered microarrays has vast importance for many applications in sensing and diagnostics. Here, the immobilization of small molecule compounds and protein in microchannel cantilever spotting (μCS) on epoxy-terminated glass surfaces is studied via ring-opening of epoxides by thiol, amine, and azide, with the...
Article
Full-text available
Immobilization of functional molecules in ordered microarrays has vast importance for many applications in sensing and diagnostics. Here, the immobilization of small molecule compounds and protein in microchannel cantilever spotting (μCS) on epoxy-terminated glass surfaces is studied via ring-opening of epoxides by thiol, amine, and azide, with the...
Article
The patterned immobilization of chemosensors into nano/microarrays has often boosted utilization in diagnostics and environmental sensing applications. While this is a standard approach for biosensors, e.g., with antibodies, other proteins, and DNA, arraying is not yet adopted widely for supramolecular chemosensors which are still predominantly use...
Article
Full-text available
Macrophages will play an important role in future diagnostics and immunotherapies of cancer. However, this demands to selectively capture and sort different subpopulations, which remains a challenge due to their innate ability to bind to a wide range of interfaces indiscriminately. The main obstacle here is the lack of interfaces combining sufficie...
Article
Full-text available
New functional initiators for the cationic ring‐opening polymerization of 2‐alkyl‐2‐oxazolines are described to introduce a thiol moiety at the α terminus. Both tosylate and nosylate initiators carrying a thioacetate group are obtained in multigram scale, from commercial reagents in two steps, including a phototriggered thiol–ene radical addition....
Article
Carbon nanofibers (CNFs), in particular branched ones, raise high interest because of their potential for nanoelectronics, catalyst presentation and applicability as dry adhesives. Here, we present a facile method based on an open ethanol flame in a microchannel for the controlled growth of coiled lambda-shaped carbon nanofibers (cλCNFs). The cλCNF...
Article
Full-text available
Biomimetic lipid membranes on solid supports have been used in a plethora of applications, including as biosensors, in research on membrane proteins or as interfaces in cell experiments. For many of these applications, structured lipid membranes, e.g., in the form of arrays with features of different functionality, are highly desired. The stability...
Article
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Polymeric biointerfaces are already being used extensively in a wide set of biomedical devices and systems. The possibility of controlling cell populations on biointerfaces may be essential for connecting biological systems to synthetic materials and for researching relevant interactions between life and matter. In this study, we present and analyz...
Article
Design of Nepenthes Pitcher inspired slippery liquid infused porous surface (SLIPS) appeared as an important avenue for various potential and practically relevant applications. In general, hydrophobic baselayers were infused with selected liquid lubricants for developing chemically inert SLIPS. Here, in this current study, an inherently hydrophilic...
Article
Anti-counterfeiting measures are becoming of ever increasing importance for our society, e.g. for securing the authen-ticity of and the proof of origin for medical drugs. Here, an arms race of counterfeiters and valid manufacturers is tak-ing place, resulting in the need of hard to forge, yet easy to read-out marks. Anti-counterfeiting measures bas...
Article
Full-text available
The level of cancer biomarkers in cells, tissues or body fluids can be used for the prediction of the presence of cancer or can even indicate the stage of the disease. Alpha-fetoprotein (AFP) is the most commonly used biomarker for early screening and diagnosis of hepatocellular carcinoma (HCC). Here, a combination of three techniques (click chemis...
Article
The "International Research Experience for Students (IRES)" at Doane University (DU) located in Crete, Nebraska, exposed undergraduate science, technology, engineering, and mathematics (STEM) students to international research at the Karlsruhe Institute of Technology (KIT) in Germany. The international collaboration team included three undergraduat...
Article
It is an active research field to develop novel strategies for sensitive and specific detection of protein biomarkers. Here we report an ultrasensitive biosensor to detect PTK7, an important protein biomarker on the cell surface, by aptamer conformation cooperated enzyme-assisted SERS (ACCESS) technology. Our approach features a synergistic combina...
Article
Full-text available
Lipid-based membranes play crucial roles in regulating the interface between cells and their external environment, the communication within cells, and cellular sensing. To study these important processes, various lipid-based artificial membrane models have been developed in recent years and, indeed, large-area arrays of supported lipid bilayers sui...
Cover Page
Full-text available
In article number 1803944, Michael Hirtz, Hendrik Holscher, and co‐workers report on the controlled growth of carbon nanofibers (CNFs) in ∧‐ or λ‐type shape in a facile open ethanol flame process. The location and number of CNFs can be precisely controlled down to a single CNF via scanning probe lithography delivered catalytic salt features. An emp...
Article
The locally defined growth of carbon nanofibers with lambda shape in an open flame process is demonstrated. Via the growth time, the geometry of the structures can be tailored to a Λ‐ or λ‐type shape. Microchannel cantilever spotting and dip‐pen nanolithography are utilized for the deposition of catalytic salt NiCl2 · 6H2O for locally controlled gr...
Article
Full-text available
Two quick and efficient, metal catalyst free conjugation routes for the covalent attachment of functional compounds to functionalized surfaces by scanning probe lithography methods are compared in the presented work. The studied methods are thiol‐yne coupling (TYC) and thiol‐ene Michael addition (TEMA). First, the surface of hydroxyl‐terminated gla...
Article
Full-text available
For many applications in the biomedical sector (especially for cell screening assays, guidance and migration experiments), gradient patterns comprising bioactive compounds over comparably (in regard to a cell size) large areas are key. Polymer pen lithography (PPL), as an inherent highly parallel and large area technique has a great potential to se...
Article
People all around the world carve their initials into trees as a symbol of eternal love. But those carvings are about 1 million times larger than the paintings that were made in living cells by Y.-W. Wu, L. Dehmelt, and co-workers in their Communication http://doi.org/10.1002/anie.201611432. Although these cell paintings were not made for eternity,...
Article
Menschen auf der ganzen Welt schnitzen ihre Initialen in Bäume als Zeichen ewiger Liebe. Diese Schnitzereien sind eine Million Mal größer als die Malereien in lebenden Zellen, die Y.-W. Wu, L. Dehmelt und Mitarbeiter in ihrer Zuschrift (http://doi.org/10.1002/ange.201611432) vorstellen. Und auch wenn diese Zellmalereien nicht für die Ewigkeit sind,...
Article
Full-text available
Nanoporous poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate) (HEMA-EDMA) is used as a 3D mesh for spotting lipid arrays. Its porous structure is an ideal matrix for lipid ink to infiltrate, resulting in higher fluorescent signal intensity as compared to similar arrays on strictly 2D substrates like glass. The embedded lipid arrays show h...
Article
Protein-repellent reactive surfaces that promote localized specific binding are highly desirable for applications in the biomedical field. Nonspecific adhesion will compromise the function of bioactive surfaces, leading to ambiguous results of binding assays and negating the binding specificity of patterned cell-adhesive motives. Localized specific...
Article
Die akute subzelluläre Rekrutierung von Proteinen ist eine leistungsfähige Methode zur Untersuchung biologischer Netzwerke. Hoch-dynamische Signalprozesse an der Plasmamembran können bisher jedoch nur bedingt räumlich und zeitlich untersucht werden. Insbesondere durch laterale Diffusion an der Plasmamembran ist eine anhaltende lokale Steuerung mole...
Article
Full-text available
Supported phospholipid membrane patches stabilized on graphene surfaces have shown potential in sensor device functionalization, including biosensors and biocatalysis. Lipid dip-pen nanolithography (L-DPN) is a method useful in generating supported membrane structures that maintain lipid functionality, such as exhibiting specific interactions with...
Article
In order to realize graphene-based chemical and bio-sensors, the nano-scale, multiplexed functionalization of graphene in a device array is a critical step. We demonstrate that graphene can be functionalized with sub-micron resolution and in well-defined locations and patterns using reaction agents in attoliter quantities, utilizing dip-pen nanolit...
Conference Paper
Polymer pen lithography (PPL) is a powerful method to generate patterns of bioactive substances with features in the nano-to microrange and over large surface areas (square centimeters). Especially, it allows for the generation of multiplexed pattern arrays (i.e. more than one component within near vicinity or within one sub-pattern). This makes th...
Cover Page
Full-text available
Microfluidic encapsulated allergen arrays are created by M. Hirtz and co-workers on page 5330 using polymer pen lithography (PPL). These arrays are utilized in mast cell activation studies on a single cell level. The overall setup enables easy handling of cell suspension, incubation, and read-out by fluorescence microscopy, allowing immune cell act...
Article
Full-text available
Multi-color patterning by polymer pen lithography (PPL) was used to fabricate covalently immobilized fluorophor- and oligonucleotide arrays with up to five different components. The oligonucleotide arrays offer a virtually unlimited inventory of orthogonal binding tags for self-assembly of proteins as demonstrated by use of the arrays to monitor ce...
Article
Phospholipid membranes of different functionalities were simultaneously assembled on arrays of graphene surfaces in a parallel manner using multi-pen lipid dip-pen nanolithography. The graphene patch facilitates and restricts the spreading of lipids within itself, obviating the need to scan the writing probes and reducing writing time. Binding stud...
Article
The profiling of allergic responses is a powerful tool in biomedical research and in judging therapeutic outcome in patients suffering from allergy. Novel insights into the signaling cascades and easier readouts can be achieved by shifting activation studies of bulk immune cells to the single cell level on patterned surfaces. The functionality of d...
Article
Tunable control of Langmuir–Blodgett (LB) patterns can be effectively realized by introducing a prestructure on the substrate. Branch structures due to instabilities are suppressed and the periodicity as well as the direction of LB patterns becomes well tunable by the prestructures. It provides the possibility to control the patterning of polymers...