Correction for 'HunStat2 - a simple and low-cost potentiostat with electrochemical impedance spectroscopy capability' by Istvan Vamos et al., Anal. Methods, 2025, 17, 9494-9499, https://doi.org/10.1039/D5AY01179E.

In metabolomics, tandem MS (MS2) fragmentation libraries are important for the identification of unknown features, but generating these libraries takes many valuable hours of instrument and operator time. Here, an immediate droplet-on-demand/open port sampling interface was used to rapidly acquire tandem MS of standards arrayed in a 96-well plate format. A workflow was developed for automated, high-throughput control of MS2 library generation. Pure standard mass spectral libraries were collected on Orbitrap and Q-TOF mass spectrometers for 192 compounds using 6 different collision energies with a throughput of 4 and 7.8 s/spectrum, respectively. Libraries were acquired using different solvent additives, precursor adducts, and ion polarities.

Silicon anodes have order of magnitude improvement in theoretical capacities over graphite counterparts for lithium-ion batteries. However, silicon exhibits large expansions upon lithiation, and the highly reducing environment deters the use of standard ethylene carbonate (EC) mixtures with lithium hexafluorophosphate (LiPF 6 ) salt. Indeed, highly soluble EC-derived polymer degradation products have been observed in both cell testing and model mechanistic studies. Thus, much effort has been made in solid electrode engineering and electrolyte design and optimization. In this vein, we developed EC-free electrolytes where large amounts of vinylene carbonate (VC) as a co-solvent with ethyl methyl carbonate (EMC) facilitated cycling stability in coin cell studies. 1 These electrolytes were further tested in ~2.3 Ah silicon oxide multilayer pouch cells and showed 80% capacity at 1,000 cycles, while cells that used EC-based electrolytes failed at ~400 cycles. 2 In this talk, we discuss the solution (neat) and solid electrode post-test analyses of these pouch cells. The VC-rich electrolyte was exceptionally clean after cycling, with no color and ca. 97% EMC by nuclear magnetic resonance spectroscopy (NMR). However, nearly all of the VC was consumed, and some polymerized VC was also observed. Fewer than ten lower-level products were observed by high-performance liquid chromatography mass spectrometry (HPLC-MS). On the other hand, the EC-containing electrolyte was dark brown with much less extractable volume and contained hundreds of species by the HPLC-MS analysis including fluorinated and non-fluorinated phosphates and EC-derived cyclic species and oligomers. On the electrode level, solid-phase NMR and X-ray photoelectron spectroscopies showed that the VC electrolyte electrodes had higher levels of lithium fluorophosphates (Li x PO y F z ), lower lithium fluoride, and fewer LiPF 6 degradation products. Overall, the combined solution and solid-state results indicate that the high concentration of VC aids in reducing the degradation cascade of PF 6 – anion in solution by favoring solid-phase fluorophosphates. The EC, conversely, appears to continually react at the surface, and undergoes full anion degradation as indicated by products such as phosphoric acid. Overall, these experiments point to the importance of electrolyte engineering for silicon anode systems and a transition away from conventional electrolyte designs based on ethylene carbonate. This research was supported by the U.S. Department of Energy’s Vehicle Technologies Office under the Silicon Consortium Project, directed by Brian Cunningham, Thomas Do, Nicolas Eidson and Carine Steinway, and managed by Anthony Burrell. The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government. 1. Woods, E. F.; Wu, D.; Robertson, L. A.; Liu, H.; Key, B.; Vaughey, J. T.; Zhang, Z. Electrolyte Design for Silicon-Based Li-Ion Battery Guided by Chemical Reactivity of Solvents with a Model Silicon Anode. ACS Appl. Energy Mater. 2024 , 7 , 8294. 2. Rodrigues, M.-T.; Trask, S.; Dunlop, A.; Lan, Y.-C.; Kubal, J.; Salpekar, D.; Prado, A. Y. R.; Wang, E.; McDaniel, C.; Robertson, L. A.; Tancin, R.; Schulze, M.; Folastre, N.; Key, B.; Zhang, Z.; Lu, W.; Abraham, D.; Jansen, A. Building high-energy silicon-containing batteries using off-the-shelf materials. J. Electrochem. Soc. 2025 , 172 , 120521.

High-throughput single-cell mass spectrometry is a rapidly evolving field that requires innovative sampling and ionization techniques to balance speed, sensitivity, and reliability for metabolomic and lipidomic analyses. This study provides a comparative analysis of two cutting-edge ionization platforms for single-cell analysis: Liquid Vortex Capture (LVC) and Rapid Droplet Sampling Interface (RDSI). The performance was benchmarked by testing pharmaceuticals, EquiSPLASH, and single-cell experiments. RDSI demonstrated up to 100-fold improvements in sensitivity for drugs and lipids such as propranolol, amiodarone, atorvastatin, and phosphocholines in water and phosphate-buffered solutions. This was attributed to its low-flow rate operation (3 μL/min) and reduced dilution. Conversely, LVC excelled in handling higher liquid volumes with greater reproducibility due to its higher solvent flow rate (200 μL/min), enabling increased dilution, solubility, and cleaning. Single-cell uptake of atorvastatin incubated for 10 min, or amiodarone incubated for 24 h in HepG2 cells, similarly revealed up to 85-fold enhancement in sensitivity by RDSI for drugs and lipids. These findings highlight the potential of RDSI for enhancing sensitivity in single-cell drug monitoring and lipidomics.

Nylons, a major class of synthetic polyamides, are widely used due to their excellent mechanical strength, thermal stability, and chemical resistance. Conventional nylon production relies on the polymerization of lactams or stoichiometric nylon salts. However, applying these approaches to unconventional precursors such as bio-derived glutaric acid produces polymers with low molecular weight and limited applications. To address these challenges, we demonstrated that chemically-synthesized nylon diads enable the production of higher-molecular-weight polyamides compared with traditional salts. We then identified a biosynthetic approach using amide synthetases to convert unprotected bifunctional substrates into nylon-relevant diads. Using a cofactor regeneration system, enzymatic diad synthesis was scaled to produce sufficient material for laboratory-scale characterization and solid-state polymerization. Amide synthetases demonstrated broad substrate scope, catalyzing the regioselective assembly of diverse nylon-relevant diacids, diamines, and omega-amino acids. This strategy offers a novel route to synthesize challenging nylon monomers and advances production of bioderived nylons.

Polyamides are important natural and synthetic polymers, best exemplified by proteins and nylons respectively. Proteins demonstrate that novel polymers with emergent properties can be generated by combining diverse monomers in precisely defined sequences. However, commercial polyamides only represent a small fraction of the potential diversity in polyamide sequences. The relative simplicity of nylon sequences derives from the challenges of controlling the incorporation of complex monomer mixtures during polymerization. In this study, we demonstrate that amide synthetases can efficiently catalyze the synthesis of sequence-defined oligoamides, ligating a broad array of commercially-relevant dicarboxylic acids with diamines and omega-amino acids at molar yields up to 80% without the need for protecting groups. These oligoamides can be chemically polymerized to yield polyamides with higher molecular weights than can be obtained from traditional nylon salts. Using a cofactor regeneration system, oligoamide synthesis was scaled to produce sufficient quantities of material for laboratory-scale characterization and solid state polymerization. This study establishes a direct biocatalytic route for the facile synthesis of sequenced oligoamides from unprotected bifunctional substrates, opening new possibilities to synthesize sequenced copolyamides. ### Competing Interest Statement LQ, ITD, JCF, and JKM are inventors on a patent application related to this work.

Block-like copolymers can be readily synthesized in one step using monomers with widely separated reactivity ratios. Here, we show that trans,trans,trans-1,5,9-cyclododecatriene (CDT), produced from polybutadiene via cyclodepolymerization (CDP), undergoes gradient copolymerization via ring-opening metathesis polymerization (ROMP) with a selected norbornene monomer to produce a block-like copolymer that exhibits bulk nanophase separation and excellent thermomechanical performance. These data highlight a new ROMP copolymerization system with a sharp compositional drift and introduce a simple pathway to convert waste plastic into a valuable building block for high-value thermoplastic materials.

Chemical selectivity is traditionally understood in the context of rigid molecular scaffolds with precisely defined local coordination and chemical environments that ultimately facilitate a given transformation of interest. By contrast, nature leverages dynamic structures and strong coupling to enable specific interactions with target species in otherwise complex media. Taking inspiration from nature, we demonstrate unconventional selectivity in the solvent extraction of light over heavy lanthanides using a conformationally flexible ligand called octadecyl acyclopa (ODA). This novel ligand forms pseudocyclic molecular complexes with lanthanide ions at organic/aqueous interfaces, revealed by vibrational sum frequency generation spectroscopy. These complexes are extracted into the organic phase, where femtosecond structural dynamics are probed by two-dimensional infrared spectroscopy and ab initio molecular dynamics simulations to mechanistically frame the macroscopic selectivity trends. We find larger-than-expected structural fluctuations and bond lengths for heavy Ln-ODA complexes that arise from an inability of ODA to contort around the smaller ions to satisfy all would-be bonding interactions, despite forming some individually strong bonds. This finding contrasts with the binding of ODA with lighter lanthanides where, despite individually weaker bonds, collective interactions manifest that minimize structural fluctuations and give rise to enhanced thermodynamic stability. These results point to a new paradigm where conformational dynamics and cumulative bonding interactions can be used to facilitate unconventional chemical transformations.

Antimony-119 (119Sb) is one of the most attractive Auger-electron emitters identified to date, but it remains practically unexplored for targeted radiotherapy because no chelators have been identified to stably bind this metalloid in vivo. In a departure from current studies focused on chelator development for Sb(III), we explore the chelation chemistry of Sb(V) using the tris-catecholate ligand TREN-CAM. Through a combination of radiolabeling, spectroscopic, solid-state, and computational studies, the radiochemistry and structural chemistry of TREN-CAM with 1XX/natSb(V) were established. The resulting [1XXSb]Sb-TREN-CAM complex remained intact for several days in human serum, signifying high stability under biological conditions. Finally, the first in vivo single photon emission computed tomography and positron emission tomography imaging studies were carried out using 117Sb, the diagnostic analogue of 119Sb. These studies revealed marked differences in the uptake and distribution of activity in mice administered unchelated [117Sb]Sb(OH)6 - versus [117Sb]Sb-TREN-CAM, suggesting that 117Sb is largely retained by TREN-CAM over the time course of the study. Collectively, these findings demonstrate the most physiologically stable complex of no-carrier-added 1XXSb yet reported, offering new promise for the clinical implementation of radioantimony in nuclear medicine. Our results also establish the feasibility of 117Sb as an elementally matched partner to 119Sb for theranostic applications.

Traditional chemical recycling approaches for condensation polymers suffer compounding energy losses and CO2 emissions across multiple polymerization and depolymerization cycles. Entropic recycling can address these energy losses by entrapping free energy within the deconstruction products. Entropic recycling involves depolymerization to macrocyclic monomers, but such processes have not been feasible due to the high dilutions typically required to generate macrocyclic compounds. Here, we leverage selective catalysis to allow entropic recycling at concentrations 20-2000x higher than typical for macrocyclization reactions. We find that Ru-based olefin metathesis catalysts containing bulky iodine ligands significantly bias the ring-chain kinetic product distribution during ring-closing metathesis (RCM) toward the formation of oligomeric cycloalkenes. Further improvements in reaction concentration and macrocycle yield are obtained by using high catalyst loadings and by predisposing the alkene substrates to undergo favorable macrocyclization. These RCM optimizations translate effectively to cyclodepolymerization (CDP) of an olefin-containing polymer, with RCM and CDP affording similar macrocycle product distributions under identical reaction conditions. Macrocycle polymerization by entropy-driven ring-opening metathesis provides much higher molecular weight polymers than condensation polymerization of linear analogues, reducing the time to achieve high molecular weight from hours to minutes and enabling polymerization at room temperature. Our findings re-emphasize the importance of energy consumption during a polymer's lifecycle and provide a framework for the design of efficient entropic recycling systems.

Single-cell mass spectrometry (MS) is advancing our understanding of metabolic pathways in heterogeneous cell populations; however, many techniques are slow or require disruptive sample preparations. This study evaluated coupling a modified HP D100 single-cell inkjet dispenser with liquid vortex capture-mass spectrometry (D100/LVC-MS). The D100 is a single-cell inkjet dispenser capable of titrating solutions and isolating single cells via disposable cassettes equipped with microfluidic channels and an impedance sensor. The LVC-MS enables high-throughput capture, lysis, and ionization of analytes for mass spectrometric analysis. The D100/LVC-MS system was characterized through titration and single-cell experiments. Propranolol titration demonstrated linearity across a broad concentration range using the D100/LVC-MS system. Additionally, Hep G2 hepatocarcinoma cells and Chlamydomonas reinhardtii algae were used to showcase the D100’s high-throughput or low-buffer-volume single-cell dispensing strategies. The D100/LVC-MS system’s performance was validated by evaluating tamoxifen-induced steatosis in Hep G2 cells. Tamoxifen, associated with nonalcoholic fatty liver disease in breast cancer patients following long-term use, was tested in Hep G2 cells at 20 µM for 72 h against DMSO-treated controls. High-throughput analysis of 500 cells per condition, completed in 25 min per run, demonstrated the system’s efficiency. The D100/LVC-MS system simultaneously quantified tamoxifen and measured triglycerides and phosphatidylcholines. Triglycerides were upregulated in the tamoxifen-treated cells and the results indicated two distinct cell populations, differing in tamoxifen and phosphatidylcholines levels, suggesting heterogeneity within the treated population. These findings highlight the D100/LVC-MS system as a cost-effective, high-throughput platform for single-cell metabolomics and lipidomics, with significant potential for evaluating metabolic alterations.

We have developed a low-cost (30 USD), simple do-it-yourself (DIY) potentiostat with cyclic voltammetry (CV), open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) capability. The HunStat2 potentiostat is based on Analog Devices' AD5941 Analog Front End chip, which significantly simplifies the construction of potentiostats for both direct and alternating current (DC and AC, respectively) techniques. Interested readers are provided with circuit diagrams and a bill of materials to build the potentiostat on their own. In addition, control software is also provided free of charge. The software enables acquisition and visualization of data. In summary, HunStat2 introduces a simple and low-cost DIY potentiostat recommended for both analytical and educational purposes.

Polyamides are important natural and synthetic polymers, best exemplified by proteins and nylons respectively. Proteins demonstrate that novel polymers with emergent properties can be generated by combining diverse monomers in precisely defined sequences. However, commercial polyamides represent only a small fraction of the potential diversity in polyamide sequences, due to the synthetic challenges of sequence-controlled polymerization. Amide synthetases have been shown to synthesize a broad array of nylon-relevant diads, but the generation of novel sequenced copolyamides requires enzymes capable of acting with longer and more diverse substrates. In this study, we demonstrated that NRPS-independent siderophore (NIS) synthetases, represented by DesD, can ligate oligomeric substrates. A simultaneous enzyme cascade using DesD enabled the synthesis of an oligotriad directly from unprotected substrates. Moreover, the regioselectivity of DesD allowed the selective synthesis of a sequenced amide tetrad, the precursor to a novel sequenced-defined polyamide with properties superior to nylon 66. This study establishes a direct biocatalytic route for the facile synthesis of sequenced oligoamides from unprotected bifunctional substrates, opening new possibilities to synthesize sequenced copolyamides. ### Competing Interest Statement LQ, ITD, JCF, and JKM are inventors on a patent application related to this work. Oak Ridge National Laboratory

RationaleThe sampling throughput of immediate drop-on-demand technology (I.DOT) coupled with an open port sampling interface (OPSI) is limited by software communication. To enable much-needed high-throughput mass spectrometry (MS) analysis capabilities, a novel software was developed that allows for flexible sample selection from a 96-well plate and for maximized analysis throughput using I.DOT/OPSI-MS coupling.MethodsWells of a 96-well I.DOT plate were filled with propranolol solution and were used to test maximum sampling throughput strategies to minimize analysis time. Demonstration of chemical reaction monitoring was done using acid-catalyzed ring closure of 2,3-diaminonaphthalene (DAN) with nitrite to form 2,3-naphthotriazole (NAT). Analytes were detected in positive electrospray ionization mode using selected reaction monitoring.ResultsA maximum throughput of 1.54 s/sample (7.41 min/96-well plate with three technical replicates) was achieved, and it was limited by the peak width of the MS signal resulting in an occasional slight overlap between the peaks. Relative standard deviation was 10 +/- 1% with all tested sampling strategies. Chemical reaction monitoring of DAN to NAT using nitrite was successfully accomplished with 2 s/sample throughout showing almost complete transformation in 10 min with no signal overlap.ConclusionsThis work illustrates the development of a noncontact, automated I.DOT/OPSI-MS system with improved throughput achieved through an optimized software interface. Its achievable analysis time and precision make it a viable approach for drug discovery and in situ reaction monitoring studies.

Enzymes have evolved to rapidly and selectively hydrolyze diverse natural and anthropogenic polymers, but only a limited group of related enzymes have been shown to hydrolyze synthetic polyamides. In this work, we synthesized and characterized a panel of 95 diverse enzymes from the N-terminal nucleophile hydrolase superfamily with 30-50% pairwise amino acid identity. We found that nearly 40% of the enzymes had substantial nylon hydrolase activity, in many cases comparable to that of the best-characterized nylon hydrolase, NylC. There was no relationship between phylogeny and activity, nor any evidence of prior selection for nylon hydrolase activity. Several newly-identified hydrolases showed significant substrate selectivity, generating up to 20-fold higher product titers with Nylon 6,6 versus Nylon 6. Finally, we determined the crystal structure and oligomerization state of a Nylon 6,6-selective hydrolase to elucidate structural factors that could affect activity and selectivity. These new enzymes provide insights into the widespread potential for nylon hydrolase evolution and opportunities for analysis and engineering of improved hydrolases.

To clinically advance the growing arsenal of radiometals available to image and treat cancer, chelators with versatile binding properties are needed. Herein, we evaluated the ability of the py2[18]dieneN6 macrocycle PYTA to interchangeably bind and stabilize 225Ac3+, [177Lu]Lu3+, [111In]In3+ and [44Sc]Sc3+, a chemically diverse set of radionuclides that can be used complementarily for targeted alpha therapy, beta therapy, single-photon emission computed tomography (SPECT) imaging, and positron emission tomography (PET) imaging, respectively. Through NMR spectroscopy and X-ray diffraction, we show that PYTA possesses an unusual degree of flexibility for a macrocyclic chelator, undergoing dramatic conformational changes that enable it to optimally satisfy the disparate coordination properties of each metal ion. Subsequent radiolabeling studies revealed that PYTA quantitatively binds all 4 radiometals at room temperature in just minutes at pH 6. Furthermore, these complexes were found to be stable in human serum over 2 half-lives. These results surpass those obtained for 2 state-of-the-art chelators for nuclear medicine, DOTA and macropa. The stability of 225Ac-PYTA and [44Sc]Sc-PYTA, the complexes having the most disparity with respect to metal-ion size, was further probed in mice. The resulting PET images (44Sc) and ex vivo biodistribution profiles (44Sc and 225Ac) of the PYTA complexes differed dramatically from those of unchelated [44Sc]Sc3+ and 225Ac3+. These differences provide evidence that PYTA retains this size-divergent pair of radionuclides in vivo. Collectively, these studies establish PYTA as a new workhorse chelator for nuclear medicine and warrant its further investigation in targeted constructs. PYTA is demonstrated to rapidly and stably complex 225Ac, 177Lu, 111In, and 44Sc, a "superfecta" of complementary but chemically distinct radiometals for targeted theranostic applications.

We have developed a truly low-cost (15 USD), simple do-it-yourself (DIY) potentiostat with compact dimensions. The output potential range of this device is between ±1.65 V. The developed instrument takes advantage of a Seeeduino XIAO microcontroller equipped with 10 bit digital-to-analog (D/A) and 12 bit analog-to-digital (A/D) converters and supports various voltammetry techniques, including cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CA). Interested users are provided with circuit diagrams, bill of materials, and design files. Additionally, software components are also provided free of charge, including an Arduino sketch and control software. The software enables easy manipulation of electrochemical parameters and visualization of results. The presented design introduces a simple and low-cost DIY potentiostat recommended for both analytical and educational purposes.

The aim of this study was to improve analysis of nonpolar lipidomics sample extracts using reversed phase (RP) chromatography. A 4/3/3 (v/v/v) mixture of methanol/methyl tert-butyl ether/chloroform (MeOH/MTBE/ CHCl3, MMC) was chosen for sample extraction solvent based on its proven extraction capability for several lipid classes. To avoid carry over, loss of analytes and peak distortion the loops and all capillaries of the presented LC system were flushed and filled up with methanol until the analytical column. The choice of methanol was due to its weak elution strength and being infinitely miscible with MMC and several other nonpolar solvents. This allowed injection of a 100 mu l sample that was 20 mu l nonpolar extraction solvent diluted fivefold with methanol. All lipids of 25 lipid classes were transferred quantitatively to the column head where the online dilution of methanol was carried out with aqueous eluent for focusing the lipid analytes. The weak elution strength of methanol prevented peak distortions. The consecutive reversed phase elution resulted in remarkably narrow peaks (full width at half maximum was 0.07-0.08 min typically) and enhanced sensitivity (limit of detection usually in sub nM region) because of increased sample injection volume and narrow peaks. Calibration and quality control samples made by diluting commercial lipid standards 200-50000 times confirmed the applicability of this approach both for targeted lipid quantification and for untargeted quantitative comparison of lipids from different sources.