Tropfenbasierte Mikroreaktoren für die Synthese von magnetischen Eisenoxid-Nanopartikeln

Continuous Electroformation of Gold Nanoparticles in Nanoliter Droplet Reactors

Gold nanoparticles (AuNPs) are employed in numerous applications, including optics, biosensing and catalysis. Here, we demonstrate the stabilizer-free electrochemical synthesis of AuNPs inside nanoliter-sized reactors. Droplets encapsulating a gold precursor are formed on a microfluidic device and exposed to an electrical current by guiding them through a pair of electrodes. We exploit the naturally occurring recirculation flows inside confined droplets (moving in rectangular microchannels) to prevent the aggregation of nanoparticles after nucleation. Therefore, AuNPs with sizes in the range of 30 to 100 nm were produced without the need of additional capping agents. The average particle size is defined by the precursor concentration and droplet velocity, while the charge dose given by the electric field strength has a minor effect. This method opens the way to fine-tune the electrochemical production of gold nanoparticles, and we believe it is a versatile method for the formation of other metal nanoparticles.

Mild Microfluidic Approaches to Oxide Nanoparticles Synthesis

Oxide nanoparticles (oxide NPs) are advanced materials with a wide variety of applications in different fields. The use of continuous flow methods is particularly appealing for their synthesis due to the high control achieved over the reaction conditions and the easy process scalability. The present review focuses on the preparation of oxide NPs using microfluidic setups at low temperature (≤80 °C), since the employment of mild reaction conditions is crucial for developing sustainable and cost-effective processes. A particular emphasis will be put on the improvement over the final product features (e. g., size, shape, and size distribution) given by flow methods with respect to conventional batch procedures. The main issues that arise by treating NPs suspensions in microfluidic systems are product deposition or channel clogging; mitigation strategies to overcome these drawbacks will also be presented and discussed.

Synthesis, Functionalization, and Design of Magnetic Nanoparticles for Theranostic Applications

In order to translate nanotechnology into medical practice, magnetic nanoparticles (MNPs) have been presented as a class of non-invasive nanomaterials for numerous biomedical applications. In particular, MNPs have opened a door for simultaneous diagnosis and brisk treatment of diseases in the form of theranostic agents. This review highlights the recent advances in preparation and utilization of MNPs from the synthesis and functionalization steps to the final design consideration in evading the body immune system for therapeutic and diagnostic applications with addressing the most recent examples of the literature in each section. This study provides a conceptual framework of a wide range of synthetic routes classified mainly as wet chemistry, state-of-the-art microfluidic reactors, and biogenic routes, along with the most popular coating materials to stabilize resultant MNPs. Additionally, key aspects of prolonging the half-life of MNPs via overcoming the sequential biological barriers are covered through unraveling the biophysical interactions at the bio-nano interface and giving a set of criteria to efficiently modulate MNPs' physicochemical properties. Furthermore, concepts of passive and active targeting for successful cell internalization, by respectively exploiting the unique properties of cancers and novel targeting ligands are described in detail. Finally, this study extensively covers the recent developments in magnetic drug targeting and hyperthermia as therapeutic applications of MNPs. In addition, multi-modal imaging via fusion of magnetic resonance imaging, and also innovative magnetic particle imaging with other imaging techniques for early diagnosis of diseases are extensively provided.

Screening for protein phosphorylation using nanoscale reactions on microdroplet arrays

We present a novel and straightforward screening method to detect protein phosphorylations in complex protein mixtures. A proteolytic digest is separated by a conventional nanoscale liquid chromatography (nano-LC) separation and the eluate is immediately compartmentalized into microdroplets, which are spotted on a microarray MALDI plate. Subsequently, the enzyme alkaline phosphatase is applied to every second microarray spot to remove the phosphate groups from phosphorylated peptides, which results in a mass shift of n×-80 Da. The MALDI-MS scan of the microarray is then evaluated by a software algorithm to automatically identify the phosphorylated peptides by exploiting the characteristic chromatographic peak profile induced by the phosphatase treatment. This screening method does not require extensive MS/MS experiments or peak list evaluation and can be easily extended to other enzymatic or chemical reactions.

Microfluidics in inorganic chemistry

The application of microfluidics in chemistry has gained significant importance in the recent years. Miniaturized chemistry platforms provide controlled fluid transport, rapid chemical reactions, and cost-saving advantages over conventional reactors. The advantages of microfluidics have been clearly established in the field of analytical and bioanalytical sciences and in the field of organic synthesis. It is less true in the field of inorganic chemistry and materials science; however in inorganic chemistry it has mostly been used for the separation and selective extraction of metal ions. Microfluidics has been used in materials science mainly for the improvement of nanoparticle synthesis, namely metal, metal oxide, and semiconductor nanoparticles. Microfluidic devices can also be used for the formulation of more advanced and sophisticated inorganic materials or hybrids.

An automated two-phase microfluidic system for kinetic analyses and the screening of compound libraries

Droplet-based microfluidic systems allow biological and chemical reactions to be performed on a drastically decreased scale. However, interfacing the outside world with such systems and generating high numbers of microdroplets of distinct chemical composition remain challenging. We describe here an automated system in which arrays of chemically distinct plugs are generated from microtiter plates. Each array can be split into multiple small-volume copies, thus allowing several screens of the same library. The system is fully compatible with further on-chip manipulation(s) and allows monitoring of individual plugs over time (e.g. for recording reaction kinetics). Hence the technology eliminates several bottlenecks of current droplet-based microfluidic systems and should open the way for (bio-)chemical and cell-based screens.