This review introduces the basic concepts and terms associated with impedance and techniques of measuring impedance. The focus of this review is on the application of this transduction method for sensing purposes. Examples of its use in combination with enzymes, antibodies, DNA and with cells will be described. Important fields of application include immune and nucleic acid analysis. Special attention is devoted to the various electrode design and amplification schemes developed for sensitivity enhancement. Electrolyte insulator semiconductor (EIS) structures will be treated separately.

This study reports on the oxygen sensitivity of quantum dot electrodes modified with CdSe/ZnS nanocrystals. The photocurrent behavior is analyzed for dependence on pH and applied potential by potentiostatic and potentiodynamic measurements. On the basis of the influence of the oxygen content in solution on the photocurrent generation, the enzymatic activity of glucose oxidase is evaluated in solution. In order to construct a photobioelectrochemical sensor which can be read out by illuminating the respective electrode area, two different immobilization methods for the fixation of the biocatalyst have been investigated. Both covalent cross-linking and layer-by-layer deposition of GOD by means of the polyelectrolyte polyallylamine hydrochloride show that a sensor construction is possible. The sensing properties of this type of electrode are drastically influenced by the amount and density of the enzyme on top of the quantum dot layer, which can be advantageously adjusted by the layer-by-layer technique. By depositing four bilayers [GOD/PAH](4) on the CdSe/ZnS electrode, a fast-responding sensor for the concentration range of 0.1-5 mM glucose can be prepared. This study opens the door to multianalyte detection with a nonstructured sensing electrode, localized enzymes, and spatial read-out by light.

The reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with sodium borohydride (NaBH4) in aqueous media is by far the most widely used reaction for testing the catalytic performance of a large variety of metal nanoparticles (MNPs) using UV/vis absorption spectroscopy. Huge differences in the kinetic rate constant of the catalytic 4-NP to 4-AP conversion as a function of material composition, size, and morphology have been reported by many different groups; so far, these have been exclusively attributed to the catalytic activity of the corresponding MNPs. In this study, we study the overlooked critical role of the pH value on the kinetics of this important reaction. We observe a strong pH dependence of both rate constant and reaction order, which we attribute to the pH-dependent hydrolysis of the reducing agent NaBH4 in water. In each hydrolysis step, molecular hydrogen as a second reducing agent is produced. Overall, two competing pathways result in: slow hydride versus fast hydrogen reduction. Kinetic simulations based on a model including all relevant species are capable of quantitatively describing all experimental results for three different noble-metal nanoparticle catalysts (Au, Pt, and Pd). Most importantly, for a fair interlaboratory comparison of the catalytic performances of MNPs, we recommend to report rate constants of the 4-NP to 4-AP conversion at pH 13 by strict pH control using a strong base such as NaOH since at pH 13 the hydrolysis of NaBH4 in aqueous solution is slowed down significantly.

Many critical advances in research utilize techniques that combine high-resolution with high-content characterization at the single cell level. We introduce the MICS (MACSima Imaging Cyclic Staining) technology, which enables the immunofluorescent imaging of hundreds of protein targets across a single specimen at subcellular resolution. MICS is based on cycles of staining, imaging, and erasure, using photobleaching of fluorescent labels of recombinant antibodies (REAfinity Antibodies), or release of antibodies (REAlease Antibodies) or their labels (REAdye_lease Antibodies). Multimarker analysis can identify potential targets for immune therapy against solid tumors. With MICS we analysed human glioblastoma, ovarian and pancreatic carcinoma, and 16 healthy tissues, identifying the pair EPCAM/THY1 as a potential target for chimeric antigen receptor (CAR) T cell therapy for ovarian carcinoma. Using an Adapter CAR T cell approach, we show selective killing of cells only if both markers are expressed. MICS represents a new high-content microscopy methodology widely applicable for personalized medicine.

Pain is a common experience of mankind. Pain theories and the management of pain have been modified throughout the history of mankind. This article gives a brief review on pain, pain believes and pain management from early magico-demonic and magico-religious ideas and procedures to more empiric-scientific models; from ancient times and primitive cultures to the 20th century. Due to new anatomical, physiological and biochemical insights, modern pain theories developed in the 19th and 20th century. Modern analgesics were synthesized and new invasive procedures were approved having a major impact on pain management strategies. However, older traditional beliefs and attitudes have not been replaced completely and have survived to some degree in modern patients.