Intraoperative Evaluation of Breast Tissues During Breast Cancer Operations Using the MasSpec Pen.

Importance: Surgery with complete tumor resection remains the main treatment option for patients with breast cancer. Yet, current technologies are limited in providing accurate assessment of breast tissue in vivo, warranting development of new technologies for surgical guidance. Objective: To evaluate the performance of the MasSpec Pen for accurate intraoperative assessment of breast tissues and surgical margins based on metabolic and lipid information. Design, Setting, and Participants: In this diagnostic study conducted between February 23, 2017, and August 19, 2021, the mass spectrometry-based device was used to analyze healthy breast and invasive ductal carcinoma (IDC) banked tissue samples from adult patients undergoing breast surgery for ductal carcinomas or nonmalignant conditions. Fresh-frozen tissue samples and touch imprints were analyzed in a laboratory. Intraoperative in vivo and ex vivo breast tissue analyses were performed by surgical staff in operating rooms (ORs) within 2 different hospitals at the Texas Medical Center. Molecular data were used to build statistical classifiers. Main Outcomes and Measures: Prediction results of tissue analyses from classification models were compared with gross assessment, frozen section analysis, and/or final postoperative pathology to assess accuracy. Results: All data acquired from the 143 banked tissue samples, including 79 healthy breast and 64 IDC tissues, were included in the statistical analysis. Data presented rich molecular profiles of healthy and IDC banked tissue samples, with significant changes in relative abundances observed for several metabolic species. Statistical classifiers yielded accuracies of 95.6%, 95.5%, and 90.6% for training, validation, and independent test sets, respectively. A total of 25 participants enrolled in the clinical, intraoperative study; all were female, and the median age was 58 years (IQR, 44-66 years). Intraoperative testing of the technology was successfully performed by surgical staff during 25 breast operations. Of 273 intraoperative analyses performed during 25 surgical cases, 147 analyses from 22 cases were subjected to statistical classification. Testing of the classifiers on 147 intraoperative mass spectra yielded 95.9% agreement with postoperative pathology results. Conclusions and Relevance: The findings of this diagnostic study suggest that the mass spectrometry-based system could be clinically valuable to surgeons and patients by enabling fast molecular-based intraoperative assessment of in vivo and ex vivo breast tissue samples and surgical margins.

A blood-based metabolomic signature predictive of risk for pancreatic cancer.

Emerging evidence implicates microbiome involvement in the development of pancreatic cancer (PaCa). Here, we investigate whether increases in circulating microbial-related metabolites associate with PaCa risk by applying metabolomics profiling to 172 sera collected within 5 years prior to PaCa diagnosis and 863 matched non-subject sera from participants in the Prostate, Lung, Colorectal, and Ovarian (PLCO) cohort. We develop a three-marker microbial-related metabolite panel to assess 5-year risk of PaCa. The addition of five non-microbial metabolites further improves 5-year risk prediction of PaCa. The combined metabolite panel complements CA19-9, and individuals with a combined metabolite panel + CA19-9 score in the top 2.5th percentile have absolute 5-year risk estimates of >13%. The risk prediction model based on circulating microbial and non-microbial metabolites provides a potential tool to identify individuals at high risk of PaCa that would benefit from surveillance and/or from potential cancer interception strategies.

Intraoperative Identification of Thyroid and Parathyroid Tissues During Human Endocrine Surgery Using the MasSpec Pen.

Importance: Intraoperative identification of tissues through gross inspection during thyroid and parathyroid surgery is challenging yet essential for preserving healthy tissue and improving outcomes for patients. Objective: To evaluate the performance and clinical applicability of the MasSpec Pen (MSPen) technology for discriminating thyroid, parathyroid, and lymph node tissues intraoperatively. Design, Setting, and Participants: In this diagnostic/prognostic study, the MSPen was used to analyze 184 fresh-frozen thyroid, parathyroid, and lymph node tissues in the laboratory and translated to the operating room to enable in vivo and ex vivo tissue analysis by endocrine surgeons in 102 patients undergoing thyroidectomy and parathyroidectomy procedures. This diagnostic study was conducted between August 2017 and March 2020. Fresh-frozen tissues were analyzed in a laboratory. Clinical analyses occurred in an operating room at an academic medical center. Of the analyses performed on 184 fresh-frozen tissues, 131 were included based on sufficient signal and postanalysis pathologic diagnosis. From clinical tests, 102 patients undergoing surgery were included. A total of 1015 intraoperative analyses were performed, with 269 analyses subject to statistical classification. Statistical classifiers for discriminating thyroid, parathyroid, and lymph node tissues were generated using training sets comprising both laboratory and intraoperative data and evaluated on an independent test set of intraoperative data. Data were analyzed from July to December 2022. Main Outcomes and Measures: Accuracy for each tissue type was measured for classification models discriminating thyroid, parathyroid, and lymph node tissues using MSPen data compared to gross analysis and final pathology results. Results: Of the 102 patients in the intraoperative study, 80 were female (78%) and the median (IQR) age was 52 (42-66) years. For discriminating thyroid and parathyroid tissues, an overall accuracy, defined as agreement with pathology, of 92.4% (95% CI, 87.7-95.4) was achieved using MSPen data, with 82.6% (95% CI, 76.5-87.4) accuracy achieved for the independent test set. For distinguishing thyroid from lymph node and parathyroid from lymph node, overall training set accuracies of 97.5% (95% CI, 92.8-99.1) and 96.1% (95% CI, 91.2-98.3), respectively, were achieved. Conclusions and Relevance: In this study, the MSPen showed high performance for discriminating thyroid, parathyroid, and lymph node tissues intraoperatively, suggesting this technology may be useful for providing near real-time feedback on tissue type to aid in surgical decision-making.

Integrated spatial transcriptomics and lipidomics of precursor lesions of pancreatic cancer identifies enrichment of long chain sulfatide biosynthesis as an early metabolic alteration.

Background: The development of diverse spatial profiling technologies has provided an unprecedented insight into molecular mechanisms driving cancer pathogenesis. Here, we conducted the first integrated cross-species assessment of spatial transcriptomics and spatial metabolomics alterations associated with progression of intraductal papillary mucinous neoplasms (IPMN), bona fide cystic precursors of pancreatic ductal adenocarcinoma (PDAC). Methods: Matrix Assisted Laster Desorption/Ionization (MALDI) mass spectrometry (MS)-based spatial imaging and Visium spatial transcriptomics (ST) (10X Genomics) was performed on human resected IPMN tissues (N= 23) as well as pancreata from a mutant Kras;Gnas mouse model of IPMN. Findings were further compared with lipidomic analyses of cystic fluid from 89 patients with histologically confirmed IPMNs, as well as single-cell and bulk transcriptomic data of PDAC and normal tissues. Results: MALDI-MS analyses of IPMN tissues revealed long-chain hydroxylated sulfatides, particularly the C24:0(OH) and C24:1(OH) species, to be selectively enriched in the IPMN and PDAC neoplastic epithelium. Integrated ST analyses confirmed that the cognate transcripts engaged in sulfatide biosynthesis, including UGT8, Gal3St1 , and FA2H , were co-localized with areas of sulfatide enrichment. Lipidomic analyses of cystic fluid identified several sulfatide species, including the C24:0(OH) and C24:1(OH) species, to be significantly elevated in patients with IPMN/PDAC compared to those with low-grade IPMN. Targeting of sulfatide metabolism via the selective galactosylceramide synthase inhibitor, UGT8-IN-1, resulted in ceramide-induced lethal mitophagy and subsequent cancer cell death in vitro , and attenuated tumor growth of mutant Kras;Gnas allografts. Transcript levels of UGT8 and FA2H were also selectively enriched in PDAC transcriptomic datasets compared to non-cancerous areas, and elevated tumoral UGT8 was prognostic for poor overall survival. Conclusion: Enhanced sulfatide metabolism is an early metabolic alteration in cystic pre-cancerous lesions of the pancreas that persists through invasive neoplasia. Targeting sulfatide biosynthesis might represent an actionable vulnerability for cancer interception.

Spatial Transcriptomics of Intraductal Papillary Mucinous Neoplasms of the Pancreas Identifies NKX6-2 as a Driver of Gastric Differentiation and Indolent Biological Potential.

Intraductal papillary mucinous neoplasms (IPMN) of the pancreas are bona fide precursor lesions of pancreatic ductal adenocarcinoma (PDAC). The most common subtype of IPMNs harbors a gastric foveolar-type epithelium, and these low-grade mucinous neoplasms are harbingers of IPMNs with high-grade dysplasia and cancer. The molecular underpinning of gastric differentiation in IPMNs is unknown, although identifying drivers of this indolent phenotype might enable opportunities for intercepting progression to high-grade IPMN and cancer. We conducted spatial transcriptomics on a cohort of IPMNs, followed by orthogonal and cross-species validation studies, which established the transcription factor NKX6-2 as a key determinant of gastric cell identity in low-grade IPMNs. Loss of NKX6-2 expression is a consistent feature of IPMN progression, while reexpression of Nkx6-2 in murine IPMN lines recapitulates the aforementioned gastric transcriptional program and glandular morphology. Our study identifies NKX6-2 as a previously unknown transcription factor driving indolent gastric differentiation in IPMN pathogenesis. SIGNIFICANCE: Identification of the molecular features driving IPMN development and differentiation is critical to prevent cancer progression and enhance risk stratification. We used spatial profiling to characterize the epithelium and microenvironment of IPMN, which revealed a previously unknown link between NKX6-2 and gastric differentiation, the latter associated with indolent biological potential. See related commentary by Ben-Shmuel and Scherz-Shouval, p. 1768. This article is highlighted in the In This Issue feature, p. 1749.

Deeper Understanding of Solvent-Based Ambient Ionization Mass Spectrometry: Are Molecular Profiles Primarily Dictated by Extraction Mechanisms?

Solvent-based ambient ionization mass spectrometry (MS) techniques provide a powerful approach for direct chemical analysis and molecular profiling of biological tissues. While molecular profiling of tissues has been widely used for disease diagnosis, little is understood about how the interplay among solvent properties, matrix effects, and ion suppression can influence the detection of biological molecules. Here, we perform a systematic investigation of the extraction processes of lipids using an ambient ionization droplet microsampling platform to investigate how the physicochemical properties of the solvent systems and extraction time influence molecular extraction and detection. Direct molecular profiling and quantitative liquid chromatography-mass spectrometry (LC-MS) of discrete solvent droplets after surface sampling were investigated to provide insights into extraction and ionization mechanisms. The results of this study suggest that intermolecular interactions such as hydrogen bonding play a major role in extraction and detection of lipids using solvent-based ambient ionization techniques. In addition, extraction time was observed to impact the molecular profiles obtained, suggesting optimization of this parameter can be performed to favor detection of specific analytes.

Clinical Translation and Evaluation of a Handheld and Biocompatible Mass Spectrometry Probe for Surgical Use.

BACKGROUND: Intraoperative tissue analysis and identification are critical to guide surgical procedures and improve patient outcomes. Here, we describe the clinical translation and evaluation of the MasSpec Pen technology for molecular analysis of in vivo and freshly excised tissues in the operating room (OR). METHODS: An Orbitrap mass spectrometer equipped with a MasSpec Pen interface was installed in an OR. A "dual-path" MasSpec Pen interface was designed and programmed for the clinical studies with 2 parallel systems that facilitated the operation of the MasSpec Pen. The MasSpec Pen devices were autoclaved before each surgical procedure and were used by surgeons and surgical staff during 100 surgeries over a 12-month period. RESULTS: Detection of mass spectral profiles from 715 in vivo and ex vivo analyses performed on thyroid, parathyroid, lymph node, breast, pancreatic, and bile duct tissues during parathyroidectomies, thyroidectomies, breast, and pancreatic neoplasia surgeries was achieved. The MasSpec Pen enabled gentle extraction and sensitive detection of various molecular species including small metabolites and lipids using a droplet of sterile water without causing apparent tissue damage. Notably, effective molecular analysis was achieved while no limitations to sequential histologic tissue analysis were identified and no device-related complications were reported for any of the patients. CONCLUSIONS: This study shows that the MasSpec Pen system can be successfully incorporated into the OR, allowing direct detection of rich molecular profiles from tissues with a seconds-long turnaround time that could be used to inform surgical and clinical decisions without disrupting tissue analysis workflows.

Rapid diagnosis and tumor margin assessment during pancreatic cancer surgery with the MasSpec Pen technology.

Intraoperative delineation of tumor margins is critical for effective pancreatic cancer surgery. Yet, intraoperative frozen section analysis of tumor margins is a time-consuming and often challenging procedure that can yield confounding results due to histologic heterogeneity and tissue-processing artifacts. We have previously described the development of the MasSpec Pen technology as a handheld mass spectrometry-based device for nondestructive tissue analysis. Here, we evaluated the usefulness of the MasSpec Pen for intraoperative diagnosis of pancreatic ductal adenocarcinoma based on alterations in the metabolite and lipid profiles in in vivo and ex vivo tissues. We used the MasSpec Pen to analyze 157 banked human tissues, including pancreatic ductal adenocarcinoma, pancreatic, and bile duct tissues. Classification models generated from the molecular data yielded an overall agreement with pathology of 91.5%, sensitivity of 95.5%, and specificity of 89.7% for discriminating normal pancreas from cancer. We built a second classifier to distinguish bile duct from pancreatic cancer, achieving an overall accuracy of 95%, sensitivity of 92%, and specificity of 100%. We then translated the MasSpec Pen to the operative room and predicted on in vivo and ex vivo data acquired during 18 pancreatic surgeries, achieving 93.8% overall agreement with final postoperative pathology reports. Notably, when integrating banked tissue data with intraoperative data, an improved agreement of 100% was achieved. The result obtained demonstrate that the MasSpec Pen provides high predictive performance for tissue diagnosis and compatibility for intraoperative use, suggesting that the technology may be useful to guide surgical decision-making during pancreatic cancer surgeries.

Homogeneous batch micro-crystallization of proteins from ammonium sulfate.

The emergence of X-ray free-electron lasers has led to the development of serial macromolecular crystallography techniques, making it possible to study smaller and more challenging crystal systems and to perform time-resolved studies on fast time scales. For most of these studies the desired crystal size is limited to a few micrometres, and the generation of large amounts of nanocrystals or microcrystals of defined size has become a bottleneck for the wider implementation of these techniques. Despite this, methods to reliably generate microcrystals and fine-tune their size have been poorly explored. Working with three different enzymes, L-aspartate α-decarboxylase, copper nitrite reductase and copper amine oxidase, the precipitating properties of ammonium sulfate were exploited to quickly transition from known vapour-diffusion conditions to reproducible, large-scale batch crystallization, circumventing the tedious determination of phase diagrams. Furthermore, the specific ammonium sulfate concentration was used to fine-tune the crystal size and size distribution. Ammonium sulfate is a common precipitant in protein crystallography, making these findings applicable to many crystallization systems to facilitate the production of large amounts of microcrystals for serial macromolecular crystallography experiments.

MASS SPECTROMETRY TECHNOLOGIES TO ADVANCE CARE FOR CANCER PATIENTS IN CLINICAL AND INTRAOPERATIVE USE.

Developments in mass spectrometry technologies have driven a widespread interest and expanded their use in cancer-related research and clinical applications. In this review, we highlight the developments in mass spectrometry methods and instrumentation applied to direct tissue analysis that have been tailored at enhancing performance in clinical research as well as facilitating translation and implementation of mass spectrometry in clinical settings, with a focus on cancer-related studies. Notable studies demonstrating the capabilities of direct mass spectrometry analysis in biomarker discovery, cancer diagnosis and prognosis, tissue analysis during oncologic surgeries, and other clinically relevant problems that have the potential to substantially advance cancer patient care are discussed. Key challenges that need to be addressed before routine clinical implementation including regulatory efforts are also discussed. Overall, the studies highlighted in this review demonstrate the transformative potential of mass spectrometry technologies to advance clinical research and care for cancer patients. © 2020 Wiley Periodicals, Inc. Mass Spec Rev.

3D-MiXD: 3D-printed X-ray-compatible microfluidic devices for rapid, low-consumption serial synchrotron crystallography data collection in flow.

Serial crystallography has enabled the study of complex biological questions through the determination of biomolecular structures at room temperature using low X-ray doses. Furthermore, it has enabled the study of protein dynamics by the capture of atomically resolved and time-resolved molecular movies. However, the study of many biologically relevant targets is still severely hindered by high sample consumption and lengthy data-collection times. By combining serial synchrotron crystallography (SSX) with 3D printing, a new experimental platform has been created that tackles these challenges. An affordable 3D-printed, X-ray-compatible microfluidic device (3D-MiXD) is reported that allows data to be collected from protein microcrystals in a 3D flow with very high hit and indexing rates, while keeping the sample consumption low. The miniaturized 3D-MiXD can be rapidly installed into virtually any synchrotron beamline with only minimal adjustments. This efficient collection scheme in combination with its mixing geometry paves the way for recording molecular movies at synchrotrons by mixing-triggered millisecond time-resolved SSX.

Spatially Controlled Molecular Analysis of Biological Samples Using Nanodroplet Arrays and Direct Droplet Aspiration.

Mass spectrometry (MS) has emerged as a valuable technology for molecular and spatial evaluation of biological samples. Ambient ionization MS techniques, in particular, allow direct analysis of tissue samples with minimal pretreatment. Here, we describe the design and optimization of an alternative ambient liquid extraction MS approach for metabolite and lipid profiling and imaging from biological samples. The system combines a piezoelectric picoliter dispenser to form solvent nanodroplets onto the sample surface with controlled and tunable spatial resolution and a conductive capillary to directly aspirate/ionize the nanodroplets for efficient analyte transmission and detection. Using this approach, we performed spatial profiling of mouse brain tissue sections with different droplet sizes (390, 420, and 500 µm). MS analysis of normal and cancerous human brain and ovarian tissues yielded rich metabolic profiles that were characteristic of disease state and enabled visualization of tissue regions with different histologic composition. This method was also used to analyze the lipid profiles of human ovarian cell lines. Overall, our results demonstrate the capabilities of this system for spatially controlled MS analysis of biological samples.

Electrochemical monitoring of the impact of polymicrobial infections on Pseudomonas aeruginosa and growth dependent medium.

The opportunistic human pathogen Pseudomonas aeruginosa (Pa) causes several infections acquired in a healthcare setting. During initial stages of infection, Pa produces redox-active phenazine metabolites, including pyocyanin (PYO), 5-methylphenazine-1-carboxylic acid (5-MCA), and 1-hydroxyphenazine (OHPHZ), which have toxic effects on surrounding host cells and/or other microbes. Rapid and sensitive detection of these metabolites provides important evidence about the onset of Pa infections. Herein, we investigate differences in Pa phenazine production and dynamics in polymicrobial communities. Specifically, Pa was co-cultured with two pathogens of clinical relevance, Staphylococcus aureus (Sa) and Escherichia coli (Ec), which typically populate infection sites with Pa. Phenazine production rates and biosynthesis dynamics were electrochemically monitored during a 48-h period using recently developed transparent carbon ultramicroelectrode arrays (T-CUAs). Moreover, the effect on phenazine production rates and dynamics was explored in two growth media, lysogeny broth (LB) and tryptic soy broth (TSB). The concentrations of PYO and highly reactive 5-MCA were determined in different polymicrobial culture samples in both media. The results demonstrate that other bacterial pathogens noticeably influence Pa phenazine production and dynamics. In particular, Sa caused a decrease in phenazine production in TSB. However, the presence of Ec in polymicrobial samples drastically inhibited phenazine production rates in both LB and TSB. Conclusively, the media type significantly influences phenazine product distribution, especially in polymicrobial co-cultures, signifying the need for analytical standardization of simulation media in the study of polymicrobial communities.

Performance of the MasSpec Pen for Rapid Diagnosis of Ovarian Cancer.

BACKGROUND: Accurate tissue diagnosis during ovarian cancer surgery is critical to maximize cancer excision and define treatment options. Yet, current methods for intraoperative tissue evaluation can be time intensive and subjective. We have developed a handheld and biocompatible device coupled to a mass spectrometer, the MasSpec Pen, which uses a discrete water droplet for molecular extraction and rapid tissue diagnosis. Here we evaluated the performance of this technology for ovarian cancer diagnosis across different sample sets, tissue types, and mass spectrometry systems. METHODS: MasSpec Pen analyses were performed on 192 ovarian, fallopian tube, and peritoneum tissue samples. Samples were evaluated by expert pathologists to confirm diagnosis. Performance using an Orbitrap and a linear ion trap mass spectrometer was tested. Statistical models were generated using machine learning and evaluated using validation and test sets. RESULTS: High performance for high-grade serous carcinoma (n = 131; clinical sensitivity, 96.7%; specificity, 95.7%) and overall cancer (n = 138; clinical sensitivity, 94.0%; specificity, 94.4%) diagnoses was achieved using Orbitrap data. Variations in the mass spectra from normal tissue, low-grade, and high-grade serous ovarian cancers were observed. Discrimination between cancer and fallopian tube or peritoneum tissues was also achieved with accuracies of 92.6% and 87.9%, respectively, and 100% clinical specificity for both. Using ion trap data, excellent results for high-grade serous cancer vs normal ovarian differentiation (n = 40; clinical sensitivity, 100%; specificity, 100%) were obtained. CONCLUSIONS: The MasSpec Pen, together with machine learning, provides robust molecular models for ovarian serous cancer prediction and thus has potential for clinical use for rapid and accurate ovarian cancer diagnosis.

Synthesis and Gelling Abilities of Polyfunctional Cyclohexane-1,2-dicarboxylic Acid Bisamides: Influence of the Hydroxyl Groups.

New enantiomerically pure C16-alkyl diamides derived from trihydroxy cyclohexane-1,2-dicarboxylic acid have been synthesized from (-)-shikimic acid. The hydroxyl groups in these compounds are free or, alternatively, they present full or partial protection. Their gelling abilities towards several solvents have been tested and rationalized by means of the combined use of Hansen solubility parameters, scanning electron microscopy (SEM), and circular dichroism (CD), as well as computational calculations. All the results allowed us to account for the capability of each type of organogelator to interact with different solvents and for the main mode of aggregation. Thus, compounds with fully protected hydroxyl groups are good organogelators for methanol and ethanol. In contrast, a related compound bearing three free hydroxyl groups is insoluble in water and polar solvents including alcohols but it is able to gelate some low-polarity solvents. This last behavior can be justified by strong hydrogen bonding between molecules of organogelator, which competes advantageously with polar solvent interactions. As an intermediate case, an organogelator with two free hydroxyl groups presents an ambivalent ability to gelate both apolar and polar solvents by means of two aggregation patterns. These involve hydrogen bonding interactions of the unprotected hydroxyl groups in apolar solvents and intermolecular interactions between amide groups in polar ones.

Real-Time Electrochemical Detection of Pseudomonas aeruginosa Phenazine Metabolites Using Transparent Carbon Ultramicroelectrode Arrays.

Here, we use a recently developed electrochemical sensing platform of transparent carbon ultramicroelectrode arrays (T-CUAs) for the in vitro detection of phenazine metabolites from the opportunistic human pathogen Pseudomonas aeruginosa. Specifically, redox-active metabolites pyocyanin (PYO), 5-methylphenazine-1-carboxylic acid (5-MCA), and 1-hydroxyphenazine (OHPHZ) are produced by P. aeruginosa, which is commonly found in chronic wound infections and in the lungs of cystic fibrosis patients. As highly diffusible chemicals, PYO and other metabolites are extremely toxic to surrounding host cells and other competing microorganisms, thus their detection is of great importance as it could provide insights regarding P. aeruginosa virulence mechanisms. Phenazine metabolites are known to play important roles in cellular functions; however, very little is known about how their concentrations fluctuate and influence cellular behaviors over the course of infection and growth. Herein we report the use of easily assembled, low-cost electrochemical sensors that provide rapid response times, enhanced sensitivity, and high reproducibility. As such, these T-CUAs enable real-time electrochemical monitoring of PYO and another extremely reactive and distinct redox-active phenazine metabolite, 5-methylphenazine-1-carboxylic acid (5-MCA), from a highly virulent laboratory P. aeruginosa strain, PA14. In addition to quantifying phenazine metabolite concentrations, changes in phenazine dynamics are observed in the biosynthetic route for the production of PYO. Our quantitative results, over a 48-h period, show increasing PYO concentrations during the first 21 h of bacterial growth, after which PYO levels plateau and then slightly decrease. Additionally, we explore environmental effects on phenazine dynamics and PYO concentrations in two growth media, tryptic soy broth (TSB) and lysogeny broth (LB). The maximum concentrations of cellular PYO were determined to be 190 ± 5 µM and 150 ± 1 µM in TSB and LB, respectively. Finally, using desorption electrospray ionization (DESI) and nanoelectrospray ionization (nano-ESI) mass spectrometry we confirm the detection and identification of reactive phenazine metabolites.

DESI Spray Stability in the Negative Ion Mode Is Dependent on Relative Humidity.

Ambient ionization mass spectrometry (MS) techniques, such as desorption electrospray ionization (DESI), have been increasingly used due to their simplicity, minimal sample preparation requirements, and potential applications in the field and the clinic. However, due to their intrinsic nature, the performance of these methods is susceptible to variations in ambient conditions. Here, we present data that suggests DESI-MS analysis becomes inconsistent below a relative humidity (RH) level of ~ 35%. At low RH, we hypothesize that the DESI spray is subjected to frequent electrical discharges, resulting in unstable ionization and atypical mass spectra. Consequentially, poor image quality is observed when used for tissue imaging. Our results suggest that RH control should be considered in DESI-MS experiments to assure data quality. Graphical Abstract ᅟ.

Synthesis and characterisation of α-carboxynitrobenzyl photocaged l-aspartates for applications in time-resolved structural biology.

We report a new synthetic route to a series of α-carboxynitrobenzyl photocaged l-aspartates for application in time-resolved structural biology. The resulting compounds were characterised in terms of UV/Vis absorption properties, aqueous solubility and stability, and photocleavage rates (τ = µs to ms) and quantum yields (φ = 0.05 to 0.14).

Cyclobutane Scaffold in Bolaamphiphiles: Effect of Diastereoisomerism and Regiochemistry on Their Surface Activity Aggregate Structure.

Cationic bolaamphiphiles have been synthesized starting from meso cis- or chiral trans-1,2-difunctionalized cyclobutane derivatives. They include cis/trans pairs of diastereoisomers, of N- or C-centered bisamides. The goal of this work was to investigate the influence of stereochemistry and regiochemistry on their abilities as surfactants and self-assembly. Very large differences in surface coverage (2-fold), critical micellar concentration (cmc, up to 2 orders of magnitude), and aggregate structure (from lamellae to fibers) for the four molecules are remarkable due to regio- and stereochemistry differences. Computational calculations were carried out to rationalize the experimental findings and a new methodology has been developed to calculate the structure of these bolaamphiphiles at the surface. Although the four surfactants adopt a wicket-like conformation, for N-centered trans, the distance between polar heads is much larger than that for the other three molecules, as suggested by calculations. We have shown that the interplay between the regiochemistry and stereoisomerism, enhanced by rigidity of the cyclobutane ring, affects different physicochemical properties quite differently. That is, the cmc value is mainly governed by stereochemistry, with regiochemistry only modulating this value. On the other hand, regiochemistry definitely governs the morphology of the supramolecular aggregates (i.e., long fibers versus plates or spherical assemblies), with stereochemistry finely modulating their structural parameters. All these results must help in the rational design of new bolaamphiphiles with predictable properties and useful potential applications.

FABP4 as a key determinant of metastatic potential of ovarian cancer.

The standard treatment for high-grade serous ovarian cancer is primary debulking surgery followed by chemotherapy. The extent of metastasis and invasive potential of lesions can influence the outcome of these primary surgeries. Here, we explored the underlying mechanisms that could increase metastatic potential in ovarian cancer. We discovered that FABP4 (fatty acid binding protein) can substantially increase the metastatic potential of cancer cells. We also found that miR-409-3p regulates FABP4 in ovarian cancer cells and that hypoxia decreases miR-409-3p levels. Treatment with DOPC nanoliposomes containing either miR-409-3p mimic or FABP4 siRNA inhibited tumor progression in mouse models. With RPPA and metabolite arrays, we found that FABP4 regulates pathways associated with metastasis and affects metabolic pathways in ovarian cancer cells. Collectively, these findings demonstrate that FABP4 is functionally responsible for aggressive patterns of disease that likely contribute to poor prognosis in ovarian cancer.