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Item type:Publication, Toward “Receive-Only” Nuclear Magnetic Resonance Complementary Metal-Oxide-Semiconductor Microcoil Arrays for High-Throughput Analysis of Environmental Samples(American Chemical Society, 2025-06-10)Daphnia magna neonates and eggs are critical life stages that show different susceptibilities to toxins and stressors compared to adults. Nuclear magnetic resonance (NMR) spectroscopy has unique potential to uncover the underlying biochemical causes, but such very small, mass-limited samples are challenging to study. While the enhanced mass sensitivity of microcoils leads to markedly improved NMR analysis, experiments are often still long, leading to low throughput. Microcoil arrays can improve throughput by allowing concurrent analysis of multiple samples, but practical and economical challenges, including expensive receivers and lack of physical space, are prohibitive. Here, approaches to overcome these challenges were examined. First, “receive-only” planar complementary metal-oxide-semiconductor (CMOS) microcoils were explored wherein the microcoil was used for detection, but an external volume coil was used for excitation. This resulted in considerably improved nutation and provided a 70% boost to the signal-to-noise ratio (SNR) compared to excitation on the planar CMOS coil. Steady-state free precession experiments further improved the SNR by a factor of at least 2.5, reducing acquisition time and improving throughput. To complete a three-coil “receive-only” array, an inexpensive ($315) software-defined radio board was adapted to act as an NMR receiver with similar performance to commercial receivers. The three-coil array was used to study three D. magna eggs concurrently, potentially opening the door for high-throughput analysis and toxicological studies, where the control and exposed cohorts can be studied concurrently, reducing day-to-day variability. Overall, microcoil arrays show considerable promise for the study of D. magna eggs and other mass-limited samples.1 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Steady State Free Precession NMR without Fourier Transform: Redefining the Capabilities of <sup>19</sup>F NMR as a Discovery Tool(Wiley, 2025-01-28)The 2024 Zurich perfluorinated compounds (PFCs) summit reiterated the urgent need for non‐selective analytical approaches for PFC detection. 19 F NMR holds great potential, however, sensitivity limitations lead to long analysis times and/or the possibility of not detecting low concentration species. Steady State Free Precession (SSFP) NMR collects the signal in a steady state regime, allowing 100's of acquisitions in the timespan of a single traditional NMR scan. Unfortunately, data truncation from SSFP leads to artifacts and spectral broadening with Fourier transform, hindering interpretation. When non‐Fourier based time‐domain analysis is used, namely, complete reduction to amplitude frequency tables (CRAFT), limitations of SSFP are eliminated while sensitivity gains are retained. This work introduces the combined approach, then applies it for the measurement of PFCs in environmental and biological samples. In all cases, the approach reduces analysis time from many hours to minutes and/or greatly increases the range of compounds detected. For example, when PFOA was spiked into human blood, the detection limit improved ~50‐fold vs standard NMR, while in a standard mixture, the approach detected compounds missed by LC‐MS/MS. The technique can be adapted to any nucleus providing a facile approach to reduce experiment time and improve sensitivity of NMR in general.4 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Steady State Free Precession NMR without Fourier Transform: Redefining the Capabilities of 19F NMR as a Discovery Tool(Wiley, 2025-04-07)F NMR holds great potential, however, sensitivity limitations lead to long analysis times and/or the possibility of not detecting low concentration species. Steady State Free Precession (SSFP) NMR collects the signal in a steady state regime, allowing 100's of acquisitions in the timespan of a single traditional NMR scan. Unfortunately, data truncation from SSFP leads to artifacts and spectral broadening with Fourier transform, hindering interpretation. When non-Fourier based time-domain analysis is used, namely, complete reduction to amplitude frequency tables (CRAFT), limitations of SSFP are eliminated while sensitivity gains are retained. This work introduces the combined approach, then applies it for the measurement of PFCs in environmental and biological samples. In all cases, the approach reduces analysis time from many hours to minutes and/or greatly increases the range of compounds detected. For example, when PFOA was spiked into human blood, the detection limit improved ~50-fold vs standard NMR, while in a standard mixture, the approach detected compounds missed by LC-MS/MS. The technique can be adapted to any nucleus providing a facile approach to reduce experiment time and improve sensitivity of NMR in general.3 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Benchtop NMR Spectroscopy of In Vivo Multicellular Organisms(American Chemical Society, 2025-07-01)NMR spectroscopy is a critical tool for environmental and biological research, but the physical and financial barriers of standard “high-field” NMR spectrometers can limit applications, especially in the environmental sciences. Low-field benchtop NMR ( 1 H resonance frequencies generally ≤100 MHz) is more accessible, but its lower sensitivity and increased spectral overlap have limited the study of complex samples. Living organisms are among the most heterogeneous samples, and it is unclear if useful information can be extracted in vivo using benchtop NMR. Here, the potential of low-field (80 MHz) in vivo NMR is first assessed by analyzing 13 C-labeling of unicellular green algae and then by monitoring a process within a multicellular organism ( T. californicus ). This is followed by studying live brine shrimp ( A. franciscana ) at 13 C natural abundance. Adults are compared to brine shrimp cysts, with a number of spectral assignments possible and differences between the life stages clearly evident. High-field NMR is used to confirm peak assignments and provide a more comprehensive characterization of biomolecules present, ultimately making the low-field NMR data more useful. Standard experiments such as 1D 1 H, 1D 13 C and 2D HSQC are conducted, as well as more advanced experiments such as 13 C-SSFP, which greatly enhances 13 C sensitivity, and reverse HSQC, which decreases spectral overlap. Ultimately, this work demonstrates that low-field NMR can effectively analyze live organisms with or without isotopic enrichment and that it holds great potential for future work, such as in vivo analysis of organisms directly in the field if/when portable NMR spectrometers become available.5