Nanoscale or single-cell technologies are critical for biomedical applications. However, current mass spectrometry (MS)-based proteomic approaches require samples comprising a minimum of thousands of ...cells to provide in-depth profiling. Here, we report the development of a nanoPOTS (nanodroplet processing in one pot for trace samples) platform for small cell population proteomics analysis. NanoPOTS enhances the efficiency and recovery of sample processing by downscaling processing volumes to <200 nL to minimize surface losses. When combined with ultrasensitive liquid chromatography-MS, nanoPOTS allows identification of ~1500 to ~3000 proteins from ~10 to ~140 cells, respectively. By incorporating the Match Between Runs algorithm of MaxQuant, >3000 proteins are consistently identified from as few as 10 cells. Furthermore, we demonstrate quantification of ~2400 proteins from single human pancreatic islet thin sections from type 1 diabetic and control donors, illustrating the application of nanoPOTS for spatially resolved proteome measurements from clinical tissues.
We report on the quantitative proteomic analysis of single mammalian cells. Fluorescence‐activated cell sorting was employed to deposit cells into a newly developed nanodroplet sample processing ...chip, after which samples were analyzed by ultrasensitive nanoLC‐MS. An average of circa 670 protein groups were confidently identified from single HeLa cells, which is a far greater level of proteome coverage for single cells than has been previously reported. We demonstrate that the single‐cell proteomics platform can be used to differentiate cell types from enzyme‐dissociated human lung primary cells and identify specific protein markers for epithelial and mesenchymal cells.
Single‐cell proteomics: A microfluidic platform coupled to nanoLC‐MS was developed to enable quantitative proteomic analysis of single mammalian cells containing only 0.1–0.2 ng of total protein. Label‐free cell differentiation was enabled by quantifying protein expression in individual cells.
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•First observation of triiodide anions from ESI of iodide salt solutions.•Absence of other trihalide anions from ESI except for Br3− in low abundance.•Formation of mixed trihalide ...anions with iodide salt spiking.•Role of physico-chemical characteristics in triiodide anion formation.
Electrospray ionization of alkali halide solutions in the negative ion mode results in the formation of cluster ions of the general formula, (MX)nX−. However, alkali iodides form triiodide anion, I3−, in high abundance in addition to cluster ions. Br3− ions are observed in low abundance. Also, mixed tri-halide anions, I2Y−, are observed in high abundance when a small amount (<1%) of KI is added to other alkali halide solutions. These results are explained by the uniquely different physical characteristics of lithium and the iodide ions compared with others in the series.
The ability to predict the solubility and stability of lithium polysulfide is vital in realizing longer lasting lithium-sulfur batteries. Herein we report combined experimental and computational ...analyses to understand the dissolution mechanism of lithium polysulfide species in an aprotic solvent medium. Multinuclear NMR, variable temperature ESR and sulfur K-edge XAS analyses reveal that the lithium exchange between polysulfide species and solvent molecules constitutes the first step in the dissolution process. Lithium exchange leads to de-lithiated polysulfide ions (Sn(2-)) which subsequently form highly reactive free radicals through dissociation reaction (Sn(2-) → 2Sn/2˙(-)). The energy required for the dissociation and possible dimer formation reactions of the polysulfide species is analyzed using density functional theory (DFT) based calculations. Based on these findings, we discuss approaches to optimize the electrolyte in order to control the polysulfide solubility.
The legendary river Saraswati of Indian mythology has often been hypothesized to be an ancient perennial channel of the seasonal river Ghaggar that flowed through the heartland of the Bronze Age ...Harappan civilization in north-western India. Despite the discovery of abundant settlements along a major paleo-channel of the Ghaggar, many believed that the Harappans depended solely on monsoonal rains, because no proof existed for the river's uninterrupted flow during the zenith of the civilization. Here, we present unequivocal evidence for the Ghaggar's perennial past by studying temporal changes of sediment provenance along a 300 km stretch of the river basin. This is achieved using
Ar/
Ar ages of detrital muscovite and Sr-Nd isotopic ratios of siliciclastic sediment in fluvial sequences, dated by radiocarbon and luminescence methods. We establish that during 80-20 ka and 9-4.5 ka the river was perennial and was receiving sediments from the Higher and Lesser Himalayas. The latter phase can be attributed to the reactivation of the river by the distributaries of the Sutlej. This revived perennial condition of the Ghaggar, which can be correlated with the Saraswati, likely facilitated development of the early Harappan settlements along its banks. The timing of the eventual decline of the river, which led to the collapse of the civilization, approximately coincides with the commencement of the Meghalayan Stage.
Spectrum sensing is the quintessence of cognitive radio network and is influenced by uncertain noise at low SNR. In such a scenario sensing duration imposes a constraint on the sensing performance. ...This paper presents a novel mathematical approach to obtain optimal sensing duration (number of samples) in presence of noise uncertainty for energy detection method. The effect of noise uncertainty on number of sensed samples has been analyzed and a novel approach has been presented to correlate the sensing duration with SNR to attain desired performance in terms of P
FA
(Probability of False Alarm) and P
D
(Probability of Detection).
Proteome profiling of circulating tumor cells (CTCs) can provide crucial insight into disease progression and the role of CTCs in tumor metastasis. We describe an integrated workflow to measure ...global protein expression in 1–5 spiked CTCs enriched from whole blood by immunodensity gradient centrifugation. Enriched CTCs were purified and collected by laser capture microdissection, prepared using a recently developed nanodroplet-based processing platform (nanoPOTS), and finally analyzed by ultrasensitive nanoLC–MS/MS. The workflow was capable of identifying an average of 164 and 607 protein groups from samples comprising 1 and 5 LNCaP cells, respectively, that were isolated from human whole blood. A panel of prostate cancer-specific proteins were identified and quantified, which was used to differentiate between spiked CTCs and white blood cells.
Sandstones of the Sanu Formation from Jaisalmer basin, western India were studied for major, trace and rare earth element (REE) geochemistry to deduce their paleo-weathering, tectonic setting, source ...rock characteristics and provenance. Geochemical results suggest that these sandstones can be classified into sub-arkose, which is supported by petrographic observations. The chemical index of alteration (CIA) values indicate intense chemical weathering. The major, trace and rare earth elements concentration pattern reveals that the sediments of the Sanu Formation were derived from silicic rock sources. The elemental discrimination diagrams specifically (Gd/Yb)
N
against Eu/Eu* suggest the Archean provenance as source possibly Aravallis for the studied samples.
Luminescence dating at the stratified prehistoric site of Attirampakkam, India, has shown that processes signifying the end of the Acheulian culture and the emergence of a Middle Palaeolithic culture ...occurred at 385 ± 64 thousand years ago (ka), much earlier than conventionally presumed for South Asia. The Middle Palaeolithic continued at Attirampakkam until 172 ± 41 ka. Chronologies of Middle Palaeolithic technologies in regions distant from Africa and Europe are crucial for testing theories about the origins and early evolution of these cultures, and for understanding their association with modern humans or archaic hominins, their links with preceding Acheulian cultures and the spread of Levallois lithic technologies. The geographic location of India and its rich Middle Palaeolithic record are ideally suited to addressing these issues, but progress has been limited by the paucity of excavated sites and hominin fossils as well as by geochronological constraints. At Attirampakkam, the gradual disuse of bifaces, the predominance of small tools, the appearance of distinctive and diverse Levallois flake and point strategies, and the blade component all highlight a notable shift away from the preceding Acheulian large-flake technologies. These findings document a process of substantial behavioural change that occurred in India at 385 ± 64 ka and establish its contemporaneity with similar processes recorded in Africa and Europe. This suggests complex interactions between local developments and ongoing global transformations. Together, these observations call for a re-evaluation of models that restrict the origins of Indian Middle Palaeolithic culture to the incidence of modern human dispersals after approximately 125 ka.
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