Integrated impedance sensing of liquid sample plug flow enables automated high throughput NMR spectroscopy

Machine Learning Advancements and Strategies in Microplastic and Nanoplastic Detection

Microplastics (MPs) and nanoplastics (NPs) present formidable global environmental challenges with serious risks to human health and ecosystem sustainability. Despite their significance, the accurate assessment of environmental MP and NP pollution remains hindered by limitations in existing detection technologies, such as low resolution, substantial data volumes, and prolonged imaging times. Machine learning (ML) provides a promising pathway to overcome these challenges by enabling efficient data processing and complex pattern recognition. This systematic Review aims to address these gaps by examining the role of ML techniques combined with spectroscopy in improving the detection and characterization of NPs. We focused on the application of ML and key tools in MP and NP detection, categorizing the literature into key aspects: (1) Developing tailored strategies for constructing ML models to optimize plastic detection while expanding monitoring capabilities. Emphasis is placed on harnessing the unique molecular fingerprinting capabilities offered by spectroscopy, including both infrared (IR) and Raman spectra. (2) Providing an in-depth analysis of the challenges and issues encountered by current ML approaches for NP detection. This Review highlights the critical role of ML in advancing environmental monitoring and improving our further, deeper investigation of the widespread presence of NPs. By identifying current key challenges, this Review provides valuable insights for future direction in environmental management and public health protection.

Towards high-field applications: high-performance, low-cost iron-based superconductors

High magnetic fields play a crucial role in advancing basic sciences, fusion energy, and magnetic resonance imaging systems. However, the widespread use of high-field magnets requires affordable high-temperature superconducting wires that can carry large supercurrents. Iron-based superconductors offer an economically attractive solution to push forward important yet costly scientific programs, such as nuclear fusion reactors and next-generation particle accelerators. In this review, we start with the fabrication of iron-based superconducting wires and tapes and continue to discuss several key factors governing the current transport properties. State-of-the-art wires and tapes are introduced with emphasis on grain boundary characteristics, flux pinning, and anisotropy. The architecture of flexible conductors enables low cost, high mechanical strength, and high thermal stability. Recent progress in practical applications, including superconducting joints and insert coils, is also reviewed. Finally, we propose several key questions faced by iron-based superconductors in future practical applications.

Accelerated Screening of Protein-Ligand Interactions via Parallel T2-Weighted 19F-MRI

In drug discovery, ligands are sought that modulate the (mal-)function of medicinally relevant target proteins. In order to develop new drugs, typically a multitude of potential ligands are initially screened for binding and subsequently characterized for their affinity. Nuclear magnetic resonance (NMR) is a well-established and highly sensitive technology for characterizing such interactions. However, it has limited throughput, because only one sample can be measured at a time. In contrast, magnetic resonance imaging (MRI) is inherently parallel and MR parameters can conveniently be encoded in its images, potentially offering increased sample throughput. We explore this application using a custom-built 9-fold sample holder and a 19F-MRI coil. With this setup, we show that ligand binding can be detected by T2-weighted 19F-MRI using 4-(trifluoromethyl)benzamidine (TFBA) and trypsin as the reporter ligand and target protein, respectively. Furthermore, we demonstrate that the affinity of nonfluorinated ligands can be determined in a competition format by monitoring the dose-dependent displacement of TFBA. By comparing 19F-T2-weighted MR images of TFBA in the presence of different benzamidine (BA) concentrations-all recorded in parallel-the affinity of BA could be derived. Therefore, this approach promises parallel characterization of protein-ligand interactions and increased throughput of biochemical assays, with potential for increased sensitivity when combined with hyperpolarization techniques.

Evolution of a Combined UV/Vis and NMR Setup with Fixed Pathlengths for Mass-limited Samples

The investigation of reaction mechanisms is a complex task that usually requires the use of several techniques. To obtain as much information as possible on the reaction and any intermediates - possibly invisible to one technique - the combination of techniques is a solution. In this work we present a new setup for combined UV/Vis and NMR spectroscopy and compare it to an established alternative. The presented approach allows a versatile usage of different commercially-available components like mirrors and fiber bundles as well as different fixed pathlengths according to double transmission or single transmission measurements. While a previous approach is based on a dip-probe setup for conventional NMR probes, the new one is based on a micro-Helmholtz coil array (LiquidVoxel™). This makes the use of rectangular cuvettes possible, which ensure well-defined pathlengths allowing for quantification of species. Additionally, very low quantities of compound can be analyzed due to the microfabrication and small cuvette size used. As proof-of-principle this new setup for combined UV/Vis and NMR spectroscopy is used to examine a well-studied photochromic system of the dithienylethene compound class. A thorough comparison of the pros and cons of the two setups for combined UV/Vis and NMR measurements is performed.

Broadband stripline Lenz lens achieves 11 × NMR signal enhancement

A Lenz lens is an electrically passive conductive element that, when placed in a time-varying magnetic field, acts as a magnetic flux concentrator or a magnetic lens. In the realm of nuclear magnetic resonance (NMR), Lenz lenses have been exploited as electrically passive metallic radiofrequency interposers placed between a sample and a tuned or untuned NMR detector in order to focus the [Formula: see text]-field of the detector onto a smaller sample space. Here we explore a novel embodiment of the Lenz lens, which acts as a non-resonant stripline interposer, i.e., the [Formula: see text]-field acts along the longitudinal volume of a sample container, such as a capillary or other microfluidic channel that is coincident with the axis of the stripline. The almost vanishing self-resonance of the stripline Lenz lens, at frequencies relevant for NMR, leads to a desirable [Formula: see text]-field amplitude that is nearly perfectly uniform across the sample and hence lacking a characteristic sinusoidal modal shape. The action of Lenz' law ensures that no stray [Formula: see text]-field is found outside of the stripline's active volume. Because the stripline Lenz lens does not rely on its own geometry to achieve resonance, its frequency response is thus widely broadband for field enhancements up to a factor of 11, with only the external driving resonator properties governing the overall resonant behaviour. We explore the use of the stripline Lenz lens with a sub-nanolitre sample volume, readily detecting 4 isotopes with resonances ranging from 125.76 to 500 MHz. The concept holds potential for the NMR study of thin films, small biological samples, as well as the in situ study of battery materials.

Artificial intelligence-driven shimming for parallel high field nuclear magnetic resonance

Rapid drug development requires a high throughput screening technology. NMR could benefit from parallel detection but is hampered by technical obstacles. Detection sites must be magnetically shimmed to ppb uniformity, which for parallel detection is precluded by commercial shimming technology. Here we show that, by centering a separate shim system over each detector and employing deep learning to cope with overlapping non-orthogonal shimming fields, parallel detectors can be rapidly calibrated. Our implementation also reports the smallest NMR stripline detectors to date, based on an origami technique, facilitating further upscaling in the number of detection sites within the magnet bore.

Microfluidics engineering towards personalized oncology-a review

Identifying and monitoring the presence of cancer metastasis and highlighting inter-and intratumoral heterogeneity is a central tenet of targeted precision oncology medicine (POM). This process of relocation of cancer cells is often referred to as the missing link between a tumor and metastasis. In recent years, microfluidic technologies have been developed to isolate a plethora of different biomarkers, such as circulating tumor cells (CTCs), tumor-derived vesicles (exosomes), or cell/free nucleic acids and proteins directly from patients' blood samples. With the advent of microfluidic developments, minimally invasive and quantitative assessment of different tumors is becoming a reality. This short review article will touch briefly on how microfluidics at early-stage achievements can be combined or developed with the active vs passive microfluidic technologies, depending on whether they utilize external fields and forces (active) or just microchannel geometry and inherent fluid forces (passive) from the market to precision oncology research and our future prospectives in terms of the emergence of ultralow cost and rapid prototyping of microfluidics in precision oncology.

Highly Fluorinated Peptide Probes with Enhanced In Vivo Stability for 19 F-MRI

A labeling strategy for in vivo ¹⁹ F-MRI (magnetic resonance imaging) based on highly fluorinated, short hydrophilic peptide probes, is developed. As dual-purpose probes, they are functionalized further by a fluorophore and an alkyne moiety for bioconjugation. High fluorination is achieved by three perfluoro-tert-butyl groups, introduced into asparagine analogues by chemically stable amide bond linkages. d-amino acids and β-alanine in the sequences endow the peptide probes with low cytotoxicity and high serum stability. This design also yielded unstructured peptides, rendering all 27 ¹⁹ F substitutions chemically equivalent, giving rise to a single ¹⁹ F-NMR resonance with <10 Hz linewidth. The resulting performance in ¹⁹ F-MRI is demonstrated for six different peptide probes. Using fluorescence microscopy, these probes are found to exhibit high stability and long circulation times in living zebrafish embryos. Furthermore, the probes can be conjugated to bovine serum albumin with only amoderate increase in ¹⁹ F-NMR linewidth to ≈30 Hz. Overall, these peptide probes are hence suitable for in vivo ¹⁹ F-MRI applications.

Sample-centred shimming enables independent parallel NMR detection

Two major technical challenges facing parallel nuclear magnetic resonance (NMR) spectroscopy, at the onset, include the need to achieve exceptional [Formula: see text] homogeneity, and good inter-detector radiofrequency signal decoupling, and have remained as technical obstacles that limit high throughput compound screening via NMR. In this contribution, we consider a compact detector system, consisting of two NMR 'unit cell' resonators that implement parallel [Formula: see text] shimming with parallel radiofrequency detection, as a prototype NMR environment, pointing the way towards achieving accelerated NMR analysis. The utility of our approach is established by achieving local field correction within the bore of a 1.05T permanent magnet MRI. Our forerunner platform suppresses signal cross-coupling in the range of [Formula: see text] dB to [Formula: see text] dB, under a geometrically decoupled scheme, leading to a halving of the necessary inter-coil separation. In this permanent magnet environment, two decoupled parallel NMR detector sites simultaneously achieve narrow spectral linewidth, overcoming the spatial inhomogeneity of the magnet from 400 to 28 Hz.

In situ sensors for flow reactors – a review

A comprehensive review on integrating microfluidic reactors with in situ sensors for reaction probing of chemical transformation.