Hans H Gorris

• PhD
• Professor (Associate) at Masaryk University

The mechanisms that drive the evolution of new enzyme activities have been investigated by comparing the kinetics of wildtype and in vitro evolved β-glucuronidase (GUS) at the single molecule level. Several hundred single GUS molecules were separated in large arrays of 62 500 ultrasmall reaction chambers etched into the surface of a fused silica sl...

Photon-upconverting nanoparticles (UCNPs) emit light of shorter wavelength under near-infrared excitation and thus avoid optical background interference. We have exploited this unique photophysical feature to establish a sensitive competitive immunoassay for the detection of the pharmaceutical micropollutant diclofenac (DCF) in water. The so-called...

Single-molecule (digital) immunoassays provide the ability to detect much lower protein concentrations than conventional immunoassays. As photon-upconversion nanoparticles (UCNPs) can be detected without optical background interference, they are excellent labels for so-called single-molecule upconversion-linked immunosorbent assays (ULISAs). We hav...

The detection of cancer biomarkers in histological samples and blood is of paramount importance for clinical diagnosis. Current methods are limited in terms of sensitivity, hindering early detection of disease. We have overcome the shortcomings of currently available staining and fluorescence labeling methods by taking an integrative approach to es...

The COVID-19 crisis requires fast and highly sensitive tests for the early stage detection of the SARS-CoV-2 virus. For detecting the nucleocapsid protein (N protein), the most abundant viral antigen, we have employed upconversion nanoparticles that emit short-wavelength light under near-infrared excitation (976 nm). The anti-Stokes emission avoids...

Sensitive immunoassays for the detection of tumor biomarkers play an important role in early diagnosis and therapy of cancer. Using luminescent nanomaterials as labels can significantly improve immunoassay performance, especially...

The demand for highly sensitive methods of pathogen detection drives the development of new diagnostic assays. While nucleic acid amplification methods such as PCR are very sensitive and remain widely used, they may be limited in complex sample matrices due to the presence of polymerase inhibitors. On the other hand, the direct detection of nucleic...

Early-stage diagnosis of prostatic carcinoma is essential for successful treatment and, thus, significant prognosis improvement. In laboratory practice, the standard non-invasive diagnostic approach is the immunochemical detection of the associated...

Dot-blot immunoassays are widely used for the user-friendly detection of clinical biomarkers. However, the majority of dot-blot assays have only limited sensitivity and are only used for qualitative or semiquantitative analysis. To overcome this limitation, we have employed labels based on photon-upconversion nanoparticles (UCNPs) that exhibit anti...

In recent years, nanotechnology has found widespread applications in environmental monitoring, medical applications, plant fertilisers, cosmetics and others. Therefore, it is important to study nanomaterials' influence and subsequent risks to the environment and organisms (from production to disposal). Therefore, in the present study, the toxic eff...

Advances in the development of new biorecognition elements, nanoparticle‐based labels as well as instrumentation have inspired the design of new bioaffinity assays. This review critically discusses the potential of nanoparticles to replace current enzymatic or molecular labels in immunoassays and other bioaffinity assays. We highlight successful im...

Otto Wolfbeis, Professor emeritus of Analytical Chemistry at the University of Regensburg, passed away on June 1, 2023. Along with his seminal work on optical sensors and fluorescent (nano)materials, he will be remembered as an outstanding researcher who inspired many talents around the world. image

Photon upconversion is an intensively investigated phenomenon in the materials sciences due to its unique applications, mainly in biomedicine for disease prevention and treatment. This study reports the synthesis and properties of tetragonal LiYbF4:Tm3+@LiYF4 core@shell nanoparticles (NPs) and their applications. The NPs had sizes ranging from 18.5...

This Perspective provides a concise overview of the field of Luminescence Sensing, which enables highly sensitive, selective, and versatile measurements. The emergence of new luminescent nanomaterials and the prospective of deploying new luminescence‐based detection schemes for solving real‐world problems, e. g., in medical diagnosis, food safety,...

Conventional immunochemical methods used in clinical analysis are often not sensitive enough for early-stage diagnosis, resulting in the need for novel assay formats. Here, we provide a detailed comparison of the effect of different labels and solid supports on the performance of heterogeneous immunoassays. When comparing three types of streptavidi...

A nanocomposite consisting of a cubic EuSe semiconductor material grown on a hexagonal upconversion nanoparticle has overcome the crystal lattice mismatch that typically prevents the epitaxial growth of such heterogeneous nanocrystals. Eu3+ at the interface layer shows its characteristic red emission band both under UV excitation light due to energ...

Surface engineering of upconverting nanoparticles (UCNPs) is crucial for their bioanalytical applications. Here, an antibody specific to cardiac troponin I (cTnI), an important biomarker for acute myocardial infection, was covalently immobilized on the surface of UCNPs to prepare a label for the detection of cTnI biomarker in an upconversion-linked...

Sensitive immunoassays are required for troponin, a low‐abundance cardiac biomarker in blood. In contrast to conventional (analog) assays that measure the integrated signal of thousands of molecules, digital assays are based on counting individual biomarker molecules. Photon‐upconversion nanoparticles (UCNP) are an excellent nanomaterial for labeli...

Immunohistochemistry (IHC) and immunocytochemistry (ICC) are widely used to identify cancerous cells within tissues and cell cultures. Even though the optical microscopy evaluation is considered the gold standard, the limited range of useful labels and narrow multiplexing capabilities create an imminent need for alternative readout techniques. Lase...

American foulbrood (AFB) caused by the bacterium Paenibacillus larvae , it is the most destructive disease of the honeybee brood. Therefore, rapid and sensitive detection methods are required to limit spreading of this pathogen, which has a major impact on agriculture and biodiversity. While P. larvae is typically detected by microbial cultivation...

Food safety and quality regulations inevitably call for sensitive and accurate analytical methods to detect harmful contaminants in food and to ensure safe food for the consumer. Both novel and well-established biorecognition elements, together with different transduction schemes, enable the simple and rapid analysis of various food contaminants. U...

Due to increasing food safety standards, the analysis of mycotoxins has become essential in the food industry. In this work, we have developed a competitive upconversion-linked immunosorbent assay (ULISA) for the analysis of zearalenone (ZEA), one of the most frequently encountered mycotoxins in food worldwide. Instead of a toxin-conjugate conventi...

Lanthanide-doped upconversion nanoparticles (UCNPs) display highly beneficial photophysical features for background-free bioimaging and bioanalysis; however, they are instable in high ionic strength buffers, have no functional groups, and are non-specifically interacting. Here, we have prepared NIR-excitable UCNPs that are long-term colloidally sta...

The ability to detect low concentrations of analytes and in particular low‐abundance biomarkers is of fundamental importance, e.g., for early‐stage disease diagnosis. The prospect of reaching the ultimate limit of detection has driven the development of single‐molecule bioaffinity assays. While many review articles have highlighted the potentials o...

Immunohistochemistry (IHC) and immunocytochemistry (ICC) are routinely employed for the microscopic identification and diagnosis of cancerous cells in histological tissues and cell cultures. The maximally attainable contrast of conventional histological staining techniques, however, is low. While the anti-Stokes emission of photon-upconversion nano...

In this report, the effects of forced convection on scanning electrochemical microscopy (SECM) studies of enzymes in the context of the generator-collector mode (G/C mode) were investigated. Forced convection was generated via an electrical high precision stirrer integrated into the electrochemical cell. Circular spots of glucose oxidase were immob...

Einzelbetrachtung : Die Notwendigkeit, äußerst niedrige Konzentrationen von Analyten und Biomarkern nachzuweisen, treibt die Entwicklung von Einzelmolekül‐Bioaffinitätsassays voran. Dieser Aufsatz hebt die Vielseitigkeit optischer Einzelmolekül‐Markierungstechniken hervor, einschließlich enzymatischer Verstärkung, Nanopartikelmarkierung und molekul...

The Conference and Spring School on Properties, Design and Applications of Upconversion Nanomaterials (UPCON) provides a new forum for all experts and newcomers in the field of upconversion research. On the occasion of the second UPCON 2018 in Valencia (Spain), we are pleased to present a collection of 12 reviews and research articles that reflect...

European foulbrood (EFB) is an infectious disease affecting honeybee larvae caused by the bacterium Melissococcus plutonius. The enzyme-linked immunosorbent assay (ELISA) is the gold standard for antibody-based bacteria detection, however, its sensitivity is not high enough to reveal early-stage EFB infection. Photon-upconversion nanoparticles (UCN...

The performance of photon-upconversion nanoparticles (UCNPs) as background-free luminescent labels in bioanalytical applications strongly depends on the preparation of well-defined and water-dispersible nanoconjugates. We have exploited the separation power of agarose gel electrophoresis to purify milligram amounts of homogeneous UCNPs covered with...

The unique photoluminescent properties of upconversion nanoparticles (UCNPs) have attracted worldwide research interest and inspired many bioanalytical applications. The anti‐Stokes emission with long luminescence lifetimes, narrow and multiple absorption and emission bands, and excellent photostability enable background‐free and multiplexed detect...

Azobenzenes are of particular interest as a photochromic scaffold for biological applications because of their high fatigue resistance, their large geometrical change between extended (trans) and bent (cis) isomer, and their diverse synthetic accessibility. Despite their wide-spread use, there is no reported photochromic inhibitor of the well-inves...

Transition state theory (TST) provides an important framework for analyzing and explaining the reaction rates of enzymes. TST, however, needs to account for protein dynamic effects and heterogeneities in enzyme catalysis. We have analyzed the reaction rates of β-galactosidase and β-glucuronidase at the single molecule level by using large arrays of...

The non-steroidal anti-inflammatory drug and analgesic diclofenac is a common micropollutant in water. A direct competitive upconversion-linked immunosorbent assay (ULISA) for diclofenac has been developed that is based on a nanoparticulate tracer consisting of a NaYF4:Yb,Er core (diameter of ~90 nm, excitation and emission wavelenghts 980 and 535...

The ability to detect disease markers at the single molecule level promises the ultimate sensitivity in clinical diagnosis. Fluorescence-based single molecule analysis, however, is limited by matrix interference and can only probe a very small detection volume, which is typically not suitable for real world analytical applications. We have develope...

Lanthanide-doped photon-upconversion nanoparticles (UCNPs) have been the focus of many research activities in materials and life sciences in the last 15 years because of their potential to convert light between different spectral regions and their unique photophysical properties. To fully exploit the application potential of these fascinating nanom...

In Part II of this review series on lanthanide-doped photon-upconversion nanoparticles (UCNPs), we present and critically discuss the performance and suitability of UCNPs as background-free luminescent reporters in bioimaging and bioanalytical applications. The preparation of a biocompatible nanoparticle surface is an integral step for all life - s...

Um die Empfindlichkeit in der analytischen Chemie zu maximieren, liegt es nahe, einzelne Moleküle nachzuweisen. Beispiele sind DNA-Sequenzierung und Proteinanalytik mit Immunoassays.

An upconversion laser scanner has been optimized to exploit the advantages of photon-upconverting nanoparticles (UCNPs) for background-free imaging on a macroscopic scale. A collimated 980-nm laser beam afforded high local excitation densities to account for the non-linear luminescence response of UCNPs. As few as 2 000 nanoparticles were detectabl...

Large arrays of femtoliter-sized chambers are important tools for single molecule research as well as bioanalytical applications. We have optimized the design and fabrication of two array types consisting of 250 × 250 (62 500) femtoliter chambers either by surface etching of fused silica slides or by polydimethylsiloxane (PDMS) molding. Highly dilu...

Technological advances in the detection and manipulation of single molecules have enabled new insights into the function, structure and interactions of biomolecules. This Special Issue was launched to account for the rapid progress in the field of “Single Molecule Techniques”. Four original research articles and seven review articles provide an int...

Photon-upconverting nanoparticles (UCNPs) can be excited by near-infrared light and emit visible light (anti-Stokes emission) which prevents autofluorescence and light scattering of biological samples. The potential for background-free imaging has attracted wide interest in UCNPs in recent years. Small and homogeneous lanthanide-doped UCNPs that di...

Large arrays of homogeneous microwells each defining a femtoliter volume are a versatile platform for monitoring the substrate turnover of many individual enzyme molecules in parallel. The high degree of parallelization enables the analysis of a statistically representative enzyme population. Enclosing individual enzyme molecules in microwells does...

The activities of hundreds of single molecules of β-galactosidase were monitored in the presence of fluorogenic substrates and two strong binding inhibitors—D-galactal and N-p-bromobenzylamino-hydroxymethyl-cyclopentanetriol (NpBHC). The stochastic binding and release of the inhibitors to single β-galactosidase molecules was studied in both pre-ste...

Photon-upconverting nanoparticles (UCNPs) have attracted much interest as a new class of luminescent label for the background-free detection in bioanalytical applications. UCNPs as well as other nanoparticles are commonly coated with a silica shell to improve their dispersibility and chemical stability in aqueous buffer and to incorporate functiona...

Large arrays of femtoliter-sized chambers were etched into the surface of fused silica slides to enclose and observe hundreds of single horseradish peroxidase (HRP) molecules in parallel. Individual molecules of HRP oxidize the fluorogenic substrate Amplex Red to fluorescent resorufin in separate chambers, which was monitored by fluorescence micros...

The proteolytic activity of renin is a key element in the regulation of blood pressure and a main target for inhibitor design. Currently, the activity of renin and its inhibitors is mainly analyzed using radioimmunoassays or FRET-substrates, which both have their limitations. Here, a novel kinetic assay is presented that combines the advantages of...

Photon-upconverting nanoparticles (UCNPs) are lanthanide-doped nanocrystals that emit visible light under near-infrared excitation (anti-Stokes emission). This unique optical property precludes background fluorescence and light scattering from biological materials. The emission of multiple and narrow emission lines is an additional hallmark of UCNP...

Photonen aufkonvertierende Nanopartikel (photon upconverting nanoparticles, UCNPs) sind Lanthanoid-dotierte Nanokristalle, die unter Nahinfrarotanregung sichtbares Licht emittieren (Anti-Stokes-Emission). Diese einzigartige optische Eigenschaft schließt Hintergrundfluoreszenz und Lichtstreuung durch biologisches Material aus. Ein weiteres Kennzeich...

Photon upconverting nanoparticles (UCNPs) have become an important new class of optical labels. Their unique property of emitting visible light after photo-excitation with near-infrared radiation enables biological imaging without background interference or cell damage. Biological applications require UCNPs that are dispersible in water and allow t...

Photon upconverting nanoparticles convert near-infrared into visible light (anti-Stokes emission), which strongly reduces the background of autofluorescence and light scattering in biological materials. Hexagonal NaYF(4) nanocrystals doped with Yb(3+) as the sensitizer and Er(3+)/Ho(3+)/Tm(3+) as the activator display at least two emission lines th...

Dual lifetime referencing (DLR) is introduced as a rapid and self-referenced method for measuring the concentration of a fluorescent analyte in solution. The fluorescent cancer chemotherapeutic doxorubicin was chosen as a medically relevant analyte and blended with a reference dye (Ru(dpp)(3)) that displays overlapping excitation and emission spect...

Beinahe zeitgleich mit der Entwicklung der DNA-Chip-Technologie durch Fodor et al. (1991) an der Stanford University in Kalifornien wurde von Ronald Frank am Helmholtz-Zentrum für Infektionsforschung (HZI) in Braunschweig ein Verfahren zur Herstellung von Peptid-Arrays entwickelt, das als spot-Synthese bezeichnet wird (Frank, 1992). Bei diesem Verf...

The sensitivity of antibody/hapten-based labeling systems is limited by the natural affinity ceiling of immunoglobulins. Breaking this limit by antibody engineering is difficult. We thus attempted a different approach and investigated if the so-called bridge effect, a corecognition of the linker present between hapten and carrier protein during ant...

Long-wavelength absorbing labels that change their color and fluorescence upon conjugation to proteins and other biomolecules provide two critical advantages over the wealth of conventional amine-reactive labels. At first, the progress of the labeling reaction can be monitored continuously either visually or by spectrometry without prior purificati...

Intracellular oxygen is an important indicator for cell metabolism and respiration. We have designed self-referenced RGB PEBBLEs that enable a simple readout of the intracellular oxygen distribution with conventional wide-field microscopy and a standard RGB digital camera. The RGB PEBBLEs consist of a hydrophobic matrix covered with amino groups on...

Ratiometric encoding with two types of photon-upconverting nanoparticles is demonstrated. Different concentrations of filter dyes on the nanoparticle's surface are used to tune selectively one of the dual emission bands (I(code)). The second emission band (I(ref)), by contrast, serves as an internal reference to obtain ratiometric codes. Combining...

We have used coherent imaging fiber arrays as a platform for preparing chemical sensors and biosensors. Sensors can be made with spatially-discrete sensing sites for multi-analyte determinations. Micrometer sized sensors have been fabricated by etching the cores of an optical imaging fiber to create microwells and loading them with microspheres. Th...

The gastrointestinal tract is a hostile biological environment, yet not all ingested materials are destroyed. The minute differences that determine whether a substance persists or is digested, liberated, adsorbed, excreted, or taken up are still poorly understood. Most attempts to investigate the events occurring during an orogastrointestinal passa...

The compartmentalization of reactions in femtoliter (fL) containers and integration of fL containers into arrays not only enhances and accelerates chemical and biochemical analysis but also leads to new scientific methods and insights. This review introduces various fL container and array formats and explores their applications for the detection an...

Die Kompartimentierung von Reaktionen in Femtoliter(fL)-Gefäßen und die Integration von fL-Gefäßen in Arrays verstärkt und beschleunigt nicht nur die chemische und biochemische Analyse, sondern führt auch zu neuen wissenschaftlichen Methoden und Erkenntnissen. Dieser Aufsatz stellt die verschiedenen fL-Gefäße und Array-Formate vor und lotet ihre An...

The compartmentalization of reactions in femtoliter (fL) containers and integration of fL containers into arrays not only enhances and accelerates chemical and biochemical analysis but also leads to new scientific methods and insights. This review introduces various fL container and array formats and explores their applications for the detection an...

Many bioanalytic and diagnostic procedures rely on labels with which the molecule of interest can be tracked in or discriminated from accompanying like substances. Herein, we describe a new labeling and detection system based on derivatives of 2,4-dichlorophenoxyacetic acid (2,4-D) and anti-2,4-D antibodies. The 2,4-D system is highly sensitive wit...

Many individual horseradish peroxidase (HRP) molecules were isolated and observed simultaneously by fluorescence microscopy in an array of 50 000 femtoliter chambers chemically etched into the surface of a glass optical fiber bundle. The substrate turnovers of hundreds of individual HRP molecules were readily analyzed, and the large number of molec...

The notorious degradation susceptibility of peptides is a major obstacle to their use as medicinal drugs. Assays with which the stability of peptides in complex proteolytic environments can be determined are thus indispensable for peptide drug development. Herein, we describe a new peptide proteolysis assay that meets that demand. It unites the hig...

Individual enzyme molecules have been observed to possess discrete and different turnover rates due to the presence of long-lived activity states. These stable activity states are thought to result from different molecular conformations or post-translational modifications. The distributions in kinetic activity observed in previous studies were obta...

Inhibition kinetics of single-β-galactosidase molecules with the slow-binding inhibitor d-galactal have been characterized by segregating individual enzyme molecules in an array of 50,000 ultra small reaction containers and observing substrate turnover changes with fluorescence microscopy. Inhibited and active states of β-galactosidase could be cle...

Optical-fiber bundles have been employed as a versatile substrate for the fabrication of high-density microwell arrays. In this minireview, we discuss the application of optical-fiber-bundle arrays for a variety of biological problems. For genomics studies and microbial pathogen detection, individual beads have been functionalized with DNA probes a...

A ganglioside GM1 probe bearing a dark-red fluorescent dye at the sphingosine moiety of the molecule was prepared by a convenient one-pot synthesis. The labeled GM1 permitted the detection of the natural ganglioside GM1 ligand Escherichia coli heat-labile enterotoxin subunit B (EtxB) in picomole quantities on a solid support. When an epitope mappin...

Im beigefügten Abstraktband S.41, Vorträge V45, V46 und V47