Ultrasensitive Proteome Profiling for 100 Living Cells by Direct Cell Injection, Online Digestion and Nano-LC-MS/MS Analysis

Single-cell proteome analysis has always been an exciting goal because it provides crucial information about cellular heterogeneity and dynamic change. Here we presented an integrated proteome analysis device (iPAD) for 100 living cells (iPAD-100) that might be suitable for single-cell analysis. Once cells were cultured, the iPAD-100 could be applied to inject 100 living cells, to transform the living cells into peptides, and to produce protein identification results with total automation. Due to the major obstacle for detection limit of mass spectrometry, we applied the iPAD-100 to analyze the proteome of 100 cells. In total, 813 proteins were identified in a DLD-cell proteome by three duplicate runs. Gene Ontology analysis revealed that proteins from different cellular compartments were well-represented, including membrane proteins. The iPAD-100 greatly simplified the sampling process, reduced sample loss, and prevented contamination. As a result, proteins whose copy numbers were lower than 1000 were identified from 100-cell samples with the iPAD-100, showing that a detection limit of 200 zmol was achieved. With increased sensitivity of mass spectrometry, the iPAD-100 may be able to reveal bountiful proteome information from a single cell in the near future

Novel Nitrocellulose Membrane Substrate for Efficient Analysis of Circulating Tumor Cells Coupled with Surface-Enhanced Raman Scattering Imaging

The capture and detection of circulating tumor cells (CTCs) in the bloodstream of patients with cancer is crucial for the clinical diagnosis and therapy. In the present work, a facile and integrated approach based on novel nitrocellulose membrane substrate and large-scale surface-enhanced Raman scattering (SERS) imaging technology has been developed for CTCs’ sensitive detection and enumeration. The system mainly consists of three aspects: capture of CTCs in bloodstream, SERS probes labeling of the captured CTCs and large-scale SERS imaging readout of CTCs enumeration. The NC membrane was used to prepare the novel CTC-capture substrate through antibody self-assembled. It was low-cost, easily prepared and completely nontoxic. Furthermore, excellent capture efficiency of the substrate was demonstrated using nonsmall-cell lung cancer (NSCLC) cells (NCI-H1650) as target cells. As the most sensitive detection technology, SERS holds huge potential in CTCs analysis. Large-scale SERS imaging was employed in CTCs enumeration for the first time, instead of the conventional fluorescence imaging. Our SERS probes, with a simplified structure, offered highly enough sensitivity to recognize every single cell clearly. In the simulation experiment of spiking 100 cancer cells into 1 mL of human whole blood, 34 cells were captured and counted successfully according to the SERS imaging result. Our experimental results demonstrate the potential feasibility of novel NC membrane substrate coupled with large-scale SERS imaging technology for the accurate enumeration of CTCs in human whole blood

Magnetic Binary Metal–Organic Framework As a Novel Affinity Probe for Highly Selective Capture of Endogenous Phosphopeptides

Highly efficient detection of endogenous phosphopeptides from complex biosamples is essential in phosphopeptidomics analysis due to the severe disturbance caused by the chaotic biological environment. In this study, for highly selective capture of endogenous phosphopeptides, a magnetic binary metal–organic framework (MOF) with Zr–O and Ti–O centers (denoted as Fe₃O₄@PDA@Zr-Ti-MOF) was designed and synthesized by a facile postsynthetic method. Briefly, Zr-based MOF was first coated on the surface of magnetic Fe₃O₄ with polydopamine (PDA) as a linker, and then, the as-prepared Fe₃O₄@PDA@Zr-MOF was exposed to DMF solution containing TiCl₄(THF)₂, resulting in the successful synthesis of Fe₃O₄@PDA@Zr-Ti-MOF. This newly prepared Fe₃O₄@PDA@Zr-Ti-MOF owned the merits of large specific surface area, unique porous structure, and superparamagnetism as well as the enhanced dual affinities of Zr–O and Ti–O centers toward both endogenous mono-phospho-peptides and multi-phospho-peptides, showing highly improved performance with better selectivity and sensitivity compared to single-metal centered MOFs (Fe₃O₄@PDA@Zr-MOF, Fe₃O₄@PDA@Ti-MOF). The Fe₃O₄@PDA@Zr-Ti-MOF was also successfully applied to extract endogenous phosphopeptides in biological sample of human saliva. As a result, 34 mono-phosphorylated peptides and 10 multi-phosphorylated peptides were detected from merely 1 μL of pristine human saliva, confirming its bright prospects in phosphopeptidomics analysis

Metathesis Reaction-Induced Significant Improvement in Hydrogen Storage Properties of the KF-Added Mg(NH₂)₂–2LiH System

The hydrogen storage properties and mechanisms of the Mg­(NH₂)₂–2LiH system with potassium halides (KF, KCl, KBr, and KI) were investigated and discussed. The results show that the KF-added sample exhibits superior hydrogen storage properties as ∼5.0 wt % of hydrogen can be reversibly stored in the 0.08KF-added sample via a two-stage reaction with an onset dehydrogenation temperature of 80 °C. However, hydrogen storage behaviors of the samples with KCl, KBr, and KI remain almost unchanged. The fact that KF can readily react with LiH to convert to KH and LiF due to the favorable thermodynamics during ball milling should be the primary reason for its significant effects, as the presence of KH provides a synergetic thermodynamic and kinetic destabilization in the hydrogen storage reaction of the Mg­(NH₂)₂–2LiH system by declining the activation energy of the first-step dehydrogenation as a catalyst and reducing the desorption enthalpy change of the second step as a reactant. The understanding on the role played by KF sheds light on how to further decrease the operating temperature and enhance the hydrogen storage kinetics of the metal–N–H system

Multilayer Hydrophilic Poly(phenol-formaldehyde resin)-Coated Magnetic Graphene for Boronic Acid Immobilization as a Novel Matrix for Glycoproteome Analysis

Capturing glycopeptides selectively and efficiently from mixed biological samples has always been critical for comprehensive and in-depth glycoproteomics analysis, but the lack of materials with superior capture capacity and high specificity still makes it a challenge. In this work, we introduce a way first to synthesize a novel boronic-acid-functionalized magnetic graphene@phenolic-formaldehyde resin multilayer composites via a facile process. The as-prepared composites gathered excellent characters of large specific surface area and strong magnetic responsiveness of magnetic graphene, biocompatibility of resin, and enhanced affinity properties of boronic acid. Furthermore, the functional graphene composites were shown to have low detection limit (1 fmol) and good selectivity, even when the background nonglycopeptides has a concentration 100 fold higher. Additionally, enrichment efficiency of the composites was still retained after being used repeatedly (at least three times). Better yet, the practical applicability of this approach was evaluated by the enrichment of human serum with a low sample volume of 1 μL. All the results have illustrated that the magG@PF@APB has a great potential in glycoproteome analysis of complex biological samples

Heating Rate-Dependent Dehydrogenation in the Thermal Decomposition Process of Mg(BH₄)₂·6NH₃

The detailed mechanism of thermal decomposition of Mg­(BH₄)₂·6NH₃ synthesized via a mechanochemical reaction between Mg­(BH₄)₂ and NH₃ at room temperature was investigated for the first time. A six-step decomposition process, which involves several parallel and interrelated reactions, was elucidated through a series of structural examinations and property evaluations. First, the thermal decomposition of Mg­(BH₄)₂·6NH₃ evolves 3 equiv of NH₃ and forms Mg­(BH₄)₂·3NH₃. Subsequently, Mg­(BH₄)₂·3NH₃ decomposes to release an additional 1 equiv of NH₃ and 3 equiv of H₂ to produce the [MgNBHNH₃]­[BH₄] polymer. And then, [MgNBHNH₃]­[BH₄] further desorbs 3 equiv of H₂ through a three-step reaction to give rise to the formation of the polymer intermediates of [MgNBHNH₂]­[BH₄], MgNBHNH₂BH₂, and MgNBNHBH, respectively. Finally, an additional 1 equiv of H₂ is liberated from MgNBNHBH to yield Mg and BN as the resultant solid products. In total, about 7 equiv of H₂ and 4 equiv of NH₃ are released together from Mg­(BH₄)₂·6NH₃ upon heating. Moreover, there is a strong dependence of the gas compositions released from Mg­(BH₄)₂·6NH₃ on the heating rate because the decomposition reaction of Mg­(BH₄)₂·3NH₃ is sensitive to the heating rate, as the faster heating rate induces a lower ammonia evolution. The finding in this work provides us with insights into the dehydrogenation mechanisms of the metal borohydride ammoniates as hydrogen storage media

Reaction Pathways for Hydrogen Uptake of the Li–Mg–N-Based Hydrogen Storage System

Hydrogen storage properties and mechanisms of the Li₃N–<i>x</i>Mg₃N₂ (<i>x</i> = 0, 0.25, 0.5, 1.0) composites were investigated in this paper. It was found that the Li₃N–0.25Mg₃N₂ composite exhibited optimal hydrogen storage performances as it can store reversibly ∼8.4 wt % hydrogen with an onset temperature of 125 °C for dehydrogenation. Upon absorbing hydrogen, Li₃N converted to Li₂NH and LiH first and was further hydrogenated to generate LiNH₂. The newly developed LiNH₂ then reacted with Mg₃N₂ under hydrogen pressure to produce Li₂Mg₂N₃H₃ and MgNH. Finally, Li₂Mg₂N₃H₃ and MgNH along with LiNH₂ further reacted with hydrogen to form the resultant products of Mg­(NH₂)₂ and LiH. More Mg₃N₂ in the Li₃N–<i>x</i>Mg₃N₂ composites retarded Li₃N to react with H₂ at the beginning of hydrogenation due to the baffle effect but facilitated the hydrogenation of Mg₃N₂ at the second-stage hydrogenation because of the decreased particle size and the frequent contact of the constituent species

Chemical Preinsertion of Lithium: An Approach to Improve the Intrinsic Capacity Retention of Bulk Si Anodes for Li-ion Batteries

Silicon represents one of the most promising anodes for next-generation Li-ion batteries due to its very high capacity and low electrochemical potential. However, the extremely poor cycling stability caused by the huge volume change during charge/discharge prevents it from the commercial use. In this work, we propose a strategy to decrease the intrinsic volume change of bulk Si-based anodes by preinsertion Li into Si with a chemical reaction. Amorphous Li₁₂Si₇ was successfully synthesized by a hydrogen-driven reaction between LiH and Si associated with subsequent energetic ball milling. The as-prepared amorphous Li₁₂Si₇ anode exhibits significantly improved lithium storage ability as ∼70.7% of the initial charge capacity is retained after 20 cycles. This finding opens up the possibility to develop bulk Si-based anodes with high capacity, long cycling life and low fabrication cost for Li-ion batteries

Development of Versatile Metal–Organic Framework Functionalized Magnetic Graphene Core–Shell Biocomposite for Highly Specific Recognition of Glycopeptides

Protein N-glycosylation is a ubiquitous and important post-translational modification that has been involved in the development and progression of a series of human-related diseases. Until recently, the highly selective capturing of glycopeptides from complex biosamples was still significant and challenging work due to their changeable structures, ultralow abundance, and strong ion-suppressing effect. Here we first report the preparation and characterization of a novel, hydrophilic, porous biocomposite composed of magnetic graphene functionalized with metal–organic frameworks (MOFs) (MG@Zn-MOFs) able to recognize glycopeptides. Thanks to its strong magnetic responsiveness, large specific surface area, excellent biocompatibility, and unique size-exclusion effect, the MG@Zn-MOFs showed outstanding sensitivity and selectivity and good recyclability in glycopeptides analysis. More excitingly, in practical application, 517 <i>N</i>-glycopeptides within 151 unique glycoproteins were clearly identified from human serum (1 μL) treated with the MG@Zn-MOFs, which is the best result among published reports so far. All the results demonstrate the promising commercialized usage of the biocomposite for the enrichment of glycopeptides in complex samples through a convenient and efficient process. Furthermore, it is anticipated that our strategy may offer promising guidance to develop new biocomposites functionalized with bio-MOFs for glycoproteomic applications

Improved Hydrogen Storage Properties of LiBH₄ Destabilized by in Situ Formation of MgH₂ and LaH₃

A reactive composite of LiBH₄–<i>x</i>La₂Mg₁₇ was successfully prepared by means of mechanochemical reaction under 40 bar of H₂. It was found that MgH₂ and LaH₃ were readily formed in situ during high-pressure ball milling, and a strong dependency of hydrogen storage performance of the LiBH₄–<i>x</i>La₂Mg₁₇ composites on the content of La₂Mg₁₇ was observed. The as-prepared LiBH₄–0.083La₂Mg₁₇ composite under 40 bar of H₂ exhibits superior hydrogen storage properties as ∼6.8 wt % of hydrogen can be reversibly desorbed and absorbed below 400 °C. It was also purposed that the self-decomposition of MgH₂ first occurred to convert into Mg with hydrogen release upon dehydrogenation and subsequently catalyzed the reaction of LiBH₄ and LaH₃ to liberate additional hydrogen along with the formation of LaB₆ and LiH. The in situ formed MgH₂ and LaH₃ provide a synergetic thermodynamic and kinetic destabilization on the de/hydrogenation of LiBH₄, which is responsible for the distinct reduction in the operating temperatures of the as-prepared LiBH₄–<i>x</i>La₂Mg₁₇ composites