An on-line SPE-LC-MS/MS method for quantification of nucleobases and nucleosides present in biological fluids.

Solid phase extraction (SPE) and liquid chromatographic (LC) separation of nucleobases and nucleosides are challenging due to the high hydrophilicity of these compounds. Herein we report a novel on-line SPE-LC-MS/MS method for their quantification after pre-column derivatization with chloroacetaldehyde (CAA). The method proposed is selective and sensitive with limits of detection at the nano-molar level. Analysis of urine and saliva samples by using this method is demonstrated. Adenine, guanine, cytosine, adenosine, guanosine, and cytidine were found in the range from 0.19 (guanosine) to 1.83 µM (cytidine) in urine and from 0.015 (guanosine) to 0.79 µM (adenine) in saliva. Interestingly, methylation of cytidine was found to be significantly different in urine from that in saliva. While 5-hydroxymethylcytidine was detected at a very low level (<0.05 µM) in saliva, it was found to be the most prominent methylated cytidine in urine at a high level of 3.33 µM. Since on-line SPE is deployed, the proposed LC-MS/MS quantitative assay is convenient to carry out and offers good assay accuracy and repeatability.

Lysine acetyltransferase 6A maintains CD4+ T cell response via epigenetic reprogramming of glucose metabolism in autoimmunity.

Augmented CD4+ T cell response in autoimmunity is characterized by extensive metabolic reprogramming. However, the epigenetic molecule that drives the metabolic adaptation of CD4+ T cells remains largely unknown. Here, we show that lysine acetyltransferase 6A (KAT6A), an epigenetic modulator that is clinically associated with autoimmunity, orchestrates the metabolic reprogramming of glucose in CD4+ T cells. KAT6A is required for the proliferation and differentiation of proinflammatory CD4+ T cell subsets in vitro, and mice with KAT6A-deficient CD4+ T cells are less susceptible to experimental autoimmune encephalomyelitis and colitis. Mechanistically, KAT6A orchestrates the abundance of histone acetylation at the chromatin where several glycolytic genes are located, thus affecting glucose metabolic reprogramming and subsequent CD4+ T cell responses. Treatment with KAT6A small-molecule inhibitors in mouse models shows high therapeutic value for targeting KAT6A in autoimmunity. Our study provides novel insights into the epigenetic programming of immunometabolism and suggests potential therapeutic targets for patients with autoimmunity.

Targeting EMSY-mediated methionine metabolism is a potential therapeutic strategy for triple-negative breast cancer.

Cancer stem cells (CSCs) are the most intractable subpopulation of triple-negative breast cancer (TNBC) cells, which have been associated with a high risk of relapse and poor prognosis. However, eradication of CSCs continues to be difficult. Here, we integrate the multiomics data of a TNBC cohort (n = 360) to identify vital markers of CSCs. We discover that EMSY, inducing a BRCAness phenotype, is preferentially expressed in breast CSCs, promotes ALDH+ cells enrichment, and is positively correlated with poor relapse-free survival. Mechanistically, EMSY competitively binds to the Jmjc domain, which is critical for KDM5B enzyme activity, to reshape methionine metabolism, and to promote CSC self-renewal and tumorigenesis in an H3K4 methylation-dependent manner. Moreover, EMSY accumulation in TNBC cells sensitizes them to PARP inhibitors against bulk cells and methionine deprivation against CSCs. These findings indicate that clinically relevant eradication of CSCs could be achieved with a strategy that targets CSC-specific vulnerabilities in amino acid metabolism.

Inulin alleviates perfluorooctanoic acid-induced intestinal injury in mice by modulating the PI3K/AKT/mTOR signaling pathway.

Perfluorooctanoic acid (PFOA) is a widely used industrial compound that has been found to induce intestinal toxicity. However, the underlying mechanisms have not been fully clarified and effective interventions are rarely developed. Inulin, a prebiotic, has been used as a supplement in human daily life as well as in gastrointestinal diseases and metabolic disorders. In this study, male mice were exposed to PFOA with or without inulin supplementation to investigate the enterotoxicity and potential intervention effects of inulin. Mice were administered PFOA at 1 mg/kg/day, PFOA with inulin at 5 g/kg/day, or Milli-Q water for 12 weeks. Histopathological analysis showed that PFOA caused colon shortening, goblet cell reduction, and inflammatory cell infiltration. The expression of the tight junction proteins ZO-1, occludin and claudin5 significantly decreased, indicating impaired barrier function. According to the RNA-sequencing analysis, PFOA exposure resulted in 917 differentially expressed genes, involving 39 significant pathways, such as TNF signaling and cell cycle pathways. In addition, the protein expression of TNF-α, IRG-47, cyclinB1, and cyclinB2 increased, while Gadd45γ, Lzip, and Jam2 decreased, suggesting the involvement of the TNF signaling pathway, cell cycle, and cell adhesion molecules in PFOA-associated intestinal injury. Inulin intervention alleviated PFOA-induced enterotoxicity by activating the PI3K/AKT/mTOR signaling pathway and increasing the protein expression of Wnt1, ß-catenin, PI3K, Akt3, and p62, while suppressing MAP LC3ß, TNF-α, and CyclinE expression. These findings suggested that PFOA-induced intestinal injury, including inflammation and tight junction disruption, was mitigated by inulin through modifying the PI3K/AKT/mTOR signaling pathways. Our study provides valuable insights into the enterotoxic effects of PFOA and highlights the potential therapeutic role of inulin.

Characterization of SNCA Multiplication in Parkinson's Disease: 2 New Cases and Evaluation of the Literature.

Background: Alpha-synuclein (SNCA) copy number variations (CNV) have been certified as a causative mutation in patients with familial and sporadic Parkinson's disease (PD). Case: We report three SNCA duplication cases diagnosed as PD. Through whole-exome sequencing, we identified a de novo 4.56 Mb repeated region in one patient and a 2.50 Mb repeated region in familial PD with two patients. Literature review: In review of previous cases, we suggest that aggressive behavior is more remarkable in CNV4 patients. Meanwhile, frequency of cognition decline and dementia were slightly increased in CNV4 patients. We also illustrate a younger onset age in offspring than parent in familial SNCA multiplication PD cases. No difference was observed in disease duration between parent and offspring generation. Conclusions: Our findings demonstrated the clinical and genetic characteristics in PD with SNCA multiplication and provided strong evidence for genetic anticipation. These results may be instructive for future disease diagnosis and genetic counseling.

Nickle-cobalt alloy nanocrystals inhibit activation of inflammasomes.

Activation of inflammasomes-immune system receptor sensor complexes that selectively activate inflammatory responses-has been associated with diverse human diseases, and many nanomedicine studies have reported that structurally and chemically diverse inorganic nanomaterials cause excessive inflammasome activation. Here, in stark contrast to reports of other inorganic nanomaterials, we find that nickel-cobalt alloy magnetic nanocrystals (NiCo NCs) actually inhibit activation of NLRP3, NLRC4 and AIM2 inflammasomes. We show that NiCo NCs disrupt the canonical inflammasome ASC speck formation process by downregulating the lncRNA Neat1, and experimentally confirm that the entry of NiCo NCs into cells is required for the observed inhibition of inflammasome activation. Furthermore, we find that NiCo NCs inhibit neutrophil recruitment in an acute peritonitis mouse model and relieve symptoms in a colitis mouse model, again by inhibiting inflammasome activation. Beyond demonstrating a highly surprising and apparently therapeutic impact for an inorganic nanomaterial on inflammatory responses, our work suggests that nickel- and cobalt-containing nanomaterials may offer an opportunity to design anti-inflammatory nanomedicines for the therapeutics of macrophage-mediated diseases.

Endoscopic and pathological characteristics of de novo colorectal cancer: Retrospective cohort study.

BACKGROUND: Endoscopy has rapidly developed in recent years and has enabled further investigation into the origin and features of intestinal tumors. The small size and concealed position of these tumors make it difficult to distinguish them from nonneoplastic polyps and carcinoma in adenoma (CIA). The invasive depth and metastatic potential determine the operation regimen, which in turn affects the overall survival and distant prognosis. The previous studies have confirmed the malignant features and clinicopathological features of de novo colorectal cancer (CRC). AIM: To provide assistance for diagnosis and treatment, but the lack of a summary of endoscopic features and assessment of risk factors that differ from the CIA prompted us to conduct this retrospective study. METHODS: In total, 167 patients with small-sized CRCs diagnosed by endoscopy were reviewed. The patients diagnosed as advanced CRCs and other malignant cancers or chronic diseases that could affect distant outcomes were excluded. After screening, 63 cases were excluded, including 33 de novo and 30 CIA cases. Patient information, including their follow-up information, was obtained from an electronic His-system. The characteristics between two group and risk factors for invasion depth were analyzed with SPSS 25.0 software. RESULTS: Nearly half of the de novo CRCs were smaller than 1 cm (n = 16, 48.5%) and the majority were located in the distal colon (n = 26, 78.8%). The IIc type was the most common macroscopic type of de novo CRC. In a Pearson analysis, the differential degree, Sano, JNET, and Kudo types, surrounding mucosa, and chicken skin mucosa (CSM) were correlated with the invasion depth (P < 0.001). CSM was a significant risk factor for deep invasion and disturbed judgment of endoscopic ultrasound. A high degree of tumor budding and tumor-infiltrating lymphocytes are accompanied by malignancy. Finally, de novo CRCs have worse outcomes than CIA CRCs. CONCLUSION: This is the first comprehensive study to analyze the features of de novo CRCs to distinguish them from nonneoplastic polyps. It is also the first study paying attention to CSM invasive depth measurement. This study emphasizes the high metastatic potential of de novo CRCs and highlights the need for more research on this tumor type.

Temporal Dynamic of the Ratio between Monopartite Begomoviruses and Their Associated Betasatellites in Plants, and Its Modulation by the Viral Gene ßC1.

The begomovirus-betasatellite complex constantly threatens crops in Asia. However, the quantitative relationship between begomoviruses and betasatellites remains largely unknown. The quantities of tobacco curly shoot virus (TbCSV) and its betasatellite (TbCSB) and their ratio varied significantly in initial infection, and thereafter, the ratio tended to become constant. The TbCSB/TbCSV ratio in agrobacteria inoculum significantly affected that in plants in the initial infection but not thereafter. Null-mutation of ßC1 that encodes a multifunctional protein important for pathogenesis in TbCSB significantly reduced the TbCSB/TbCSV ratio in plants. Viral inoculum plants with higher TbCSB/TbCSV ratios promoted whitefly transmission of the virus. The expression of AV1 encoded by TbCSV, ßC1 encoded by TbCSB and the ßC1/AV1 ratio varied significantly in the initial infection and thereafter the ratio tended to become constant. Additionally, the temporal dynamics of the ratio between another begomovirus and its betasatellite was similar to that of TbCSV and was positively regulated by ßC1. These results indicate that the ratio between monopartite begomoviruses and betasatellites tend to become constant as infection progresses, and is modulated by ßC1, but a higher betasatellite/begomovirus ratio in virally inoculated plants promotes virus transmission by whiteflies. Our findings provide novel insights into the association between begomoviruses and betasatellites.

Combined Single-Cell and Spatial Transcriptomics Reveal the Metabolic Evolvement of Breast Cancer during Early Dissemination.

Breast cancer is now the most frequently diagnosed malignancy, and metastasis remains the leading cause of death in breast cancer. However, little is known about the dynamic changes during the evolvement of dissemination. In this study, 65 968 cells from four patients with breast cancer and paired metastatic axillary lymph nodes are profiled using single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics. A disseminated cancer cell cluster with high levels of oxidative phosphorylation (OXPHOS), including the upregulation of cytochrome C oxidase subunit 6C and dehydrogenase/reductase 2, is identified. The transition between glycolysis and OXPHOS when dissemination initiates is noticed. Furthermore, this distinct cell cluster is distributed along the tumor's leading edge. The findings here are verified in three different cohorts of breast cancer patients and an external scRNA-seq dataset, which includes eight patients with breast cancer and paired metastatic axillary lymph nodes. This work describes the dynamic metabolic evolvement of early disseminated breast cancer and reveals a switch between glycolysis and OXPHOS in breast cancer cells as the early event during lymph node metastasis.

A novel one-pot fluorescence tagging and depyrimidination strategy for quantification of global DNA methylation.

DNA methylation is intensively studied in medical science. Current HPLC methods for quantification of global DNA methylation involve digestion of a DNA sample and HPLC determination of both cytosine (C) and 5-methylcytosine (5mC) so that percentage of 5mC in total cytosine can be calculated as DNA methylation level. Herein we report a novel HPLC method based on a one-pot fluorescence tagging and depyrimidination reaction between DNA and chloroacetaldehyde (CAA) for highly sensitive quantification of global DNA methylation. In the one-pot reaction, C and 5mC residues in a DNA sequence react with CAA, forming fluorescent etheno-adducts that are then released from the sequence through depyrimidination. Interestingly, etheno-5mC (ε-5mC) is ∼20 times more fluorescent than ε-C and other ε-nucleobases resulting from the reaction, which greatly facilitates the quantification. Further, due to the tagging-induced increase in structural aromaticity, ε-nucleobases are far more separable by HPLC than intact nucleobases. The proposed HPLC method with fluorescence detection (HPLC-FD) is quick (i.e., < 1h per assay) and highly sensitive with a detection limit of 0.80 nM (or 250 fg on column) for 5mC. Using the method, DNA samples isolated from yeast, HCT-116 cells, and tissues were analyzed. Global DNA methylation was measured to be in the range from 0.35% to 2.23% in the samples analyzed. This sensitive method allowed accurate analyses of minute DNA samples (∼100 ng) isolated from milligrams of tissues.

Screening of Monoamine Oxidase B Inhibitors from Fragaria nubicola by Ligand Fishing and Their Neuroprotective Effects.

Fragaria nubicola, known as Tibetan strawberry, is an edible plant possessing various health-promoting effects. However, its functional compositions were rarely studied. In this work, monoamine oxidase B (MAO-B) inhibitors in this plant were rapidly screened using the enzyme-functionalized magnetic nanoparticles coupled with UPLC-QTOF-MS. Two inhibitors, quercetin-3-O-ß-d-glucuronide-6″-methyl ester (1) and kaempferol-3-O-ß-d-glucuronide-6″-methyl ester (2), were identified from this plant with the IC50 values of 19.44 ± 1.17 and 22.63 ± 1.78 µM, respectively. Enzyme kinetic analysis and molecular docking were carried out to investigate the mechanism of inhibition. Contents of both compounds as well as those of total phenolics and flavonoids were quantified to be 24.76 ± 1.26, 35.59 ± 1.17, 837.67 ± 10.62, and 593.46 ± 10.37 µg/g, respectively. In addition, both compounds exhibited significant neuroprotective effects on 6-hydroxydopamine-induced PC12 cells. This is the first report on the neuroprotective components of F. nubicola, suggesting its potential for developing neuroprotective functional food.

Pyogenic liver abscess in non-liver cancer patients and liver cancer patients treated with TACE: Etiological characteristics, treatment, and outcome analysis.

Clinical, laboratory, and microbiological features, clinical outcomes, and pyogenic liver abscess (PLA) prognosis evaluation in non-liver cancer (Non-LC) and liver cancer patients treated with transarterial chemoembolization (TACE, LC-TACE). Clinical data of 48 consecutive PLA patients from January 2016 to December 2020 were retrospectively analyzed. Mortality between two PLA patient groups were compared, and mortality risk factors were evaluated. A total of 48 PLA patients (31 males and 17 females) from January 2016 to December 2020 met the study's inclusion criteria. There were 32 and 16 patients in the Non-LC and LC-TACE groups, respectively. Positive pus culture rate in the Non-LC group was 87.5% and positive pus culture rate in LC-TACE group was 81.3%. In the Non-LC group, 28 patients improved after treatment, 1 patient did not improve, and 3 patients died during hospitalization, with a 9.4% mortality rate. In the LC-TACE group, nine patients improved after treatment, three patients did not improve, and four patients died during hospitalization, with a 25% mortality rate. The Non-LC group cure time was 37.4 ± 23.1 days, while the LC-TACE group was 91.5 ± 49.7 days. PLA of the Non-LC group and the LC-TACE group were different in terms of pathogenic bacteria and cure time, and so on. A more comprehensive treatment should be considered for PLA after TACE.

Remote programming for subthalamic deep brain stimulation in Parkinson's disease.

Introduction: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is effective for the treatment of Parkinson's disease (PD). Moreover, remote programming is widely used in Mainland China. This necessitates evaluating the ability of remote programming to achieve the ideal postoperative effect. Therefore, we aimed to retrospectively evaluate the effects of different programming modes on the effectiveness of STN-DBS 12 months postoperatively in patients with PD. Methods: Clinical data were collected retrospectively, before and 12 months after surgery, in 83 patients with PD. Based on the programming modes voluntarily selected by the patients during 12 months postoperatively, they were divided into three groups, namely remote programming alone, hospital programming alone, and hospital + remote programming. We compared the programming data and the effects of different programming methods on STN-DBS-related improvements 12 months postoperatively among these groups. Furthermore, we analyzed STN-DBS-related improvements at 12 months postoperatively in 76 patients. Results: The effectiveness of STN-DBS was not influenced by the three programming modes. The postoperative Movement Disorder Society Unified Parkinson's Disease Rating Scale scores did not reveal statistically significant differences between the remote alone and hospital alone programming groups, except for motor examination. The postoperative decline in the levodopa equivalent daily dose was most apparent in the hospital programming alone group. The programming frequency of the hospital + remote programming group was considerably higher than that of the remaining groups. Seventy-six patients with PD displayed good STN-DBS surgical efficacy. Conclusion: Programming modes do not influence the short-term efficacy of STN-DBS, and remote programming can yield a satisfactory surgical effect.

Efficacy and safety of intravitreal HLX04-O, an anti-VEGF monoclonal antibody, for the treatment of wet age-related macular degeneration.

AIM: To evaluate the efficacy and safety of HLX04-O, an investigational ophthalmic formulation of HLX04 (bevacizumab biosimilar) for intravitreal injection, as a treatment for wet age-related macular degeneration (wAMD) in a phase 1/2 clinical trial (NCT04993352). METHODS: Eligible patients with wAMD were enrolled to receive HLX04-O intravitreal injections at a dose of 1.25 mg/0.05 mL every four weeks. Efficacy and adverse events were evaluated every month during study visits. RESULTS: A 76-year-old male with wAMD in his left eye participated in the trial and completed six cycles of HLX04-O intravitreal injections. Changes were observed in macular center point thickness (baseline vs last study visit, 437 vs 255 µm) and best-corrected visual acuity letter score (baseline vs last study visit, 36 vs 77) of the affected eye, which indicated an improvement in wAMD over treatment. No adverse events were reported by the data cutoff date. CONCLUSION: HLX04-O at 1.25 mg/0.05 mL every four weeks is well tolerated in this patient, demonstrating promising safety and efficacy in wAMD treatment. Large-scale studies are required to confirm the outcomes.

3D parametric surface planar topological guide plate to create a PMSG for the emergency endovascular repair of an aortic arch aneurysm.

A 69-year-old male patient was admitted by 10 h severe chest pain. Computed tomography angiography showed a 7.3 cm aneurysm of the aortic arch. We used a three-dimensional parametric surface planar topological guide plate to prepare a guide plate in 40 min. The plate was used to localize the opening of the aortic arch branches on table to create a physician-modified stent graft (PMSG). The aneurysm was successfully repaired by the triple inner branched PMSG, with no endoleak and all the branched arteries patency in follow-up. This technique could not only make accurate fenestration but also meet the need for emergency surgery.

Ligand fishing based on tubular microchannel modified with monoamine oxidase B for screening of the enzyme's inhibitors from Crocus sativus and Edgeworthia gardneri.

A novel strategy of performing ligand fishing with enzyme-modified open tubular microchannel was proposed for screening bioactive components present in medicinal plants. Monoamine oxidase B was immobilized onto the surface of the microchannel for the first time to specifically extract its ligands when the plant's extracts solution flows through the channel. The thermal and the storage stability of immobilized monoamine oxidase B were significantly enhanced after immobilization. Crocin I and Ⅱ were extracted from Crocus sativus, and tiliroside was extracted from Edgeworthia gardneri. All the three compounds were inhibitors of the enzyme with the half-maximal inhibitory concentration values of 26.70 ±â€¯0.91, 19.88 ±â€¯2.78, and 15.65 ± 0.85 µM, respectively. The enzyme inhibition kinetics and molecular docking were investigated. This is the first report on the inhibitory effects of tiliroside and crocin Ⅱ. The novel ligand fishing method proposed in this work possesses advantages of rapidness, high efficiency, and tiny sample consumption compared to routine ligand fishing, with promising potential for screening active natural products in complex mixtures.

Inflammatory biomarkers and cerebral small vessel disease: a community-based cohort study.

BACKGROUND AND PURPOSE: Although inflammation has been proposed to be a candidate risk factor for cerebral small vessel disease (CSVD), previous findings remain largely inconclusive and vary according to disease status and study designs. The present study aimed to investigate possible associations between inflammatory biomarkers and MRI markers of CSVD. METHODS: A group of 15 serum inflammatory biomarkers representing a variety of those putatively involved in the inflammatory cascade was grouped and assessed in a cross-sectional study involving 960 stroke-free subjects. The biomarker panel was grouped as follows: systemic inflammation (high-sensitivity C reactive protein (hsCRP), interleukin 6 and tumour necrosis factor α), endothelial-related inflammation (E-selectin, P-selectin, intercellular adhesion molecule 1, vascular cell adhesion molecule 1 (VCAM-1), CD40 ligand, lipoprotein-associated phospholipase A2, chitinase-3-like-1 protein and total homocysteine (tHCY)) and media-related inflammation (matrix metalloproteinases 2, 3 and 9, and osteopontin). The association(s) between different inflammatory groups and white matter hyperintensity (WMH), lacunes, cerebral microbleeds (CMBs), enlarged perivascular space (PVS) and the number of deep medullary veins (DMVs) were investigated. RESULTS: High levels of serum endothelial-related inflammatory biomarkers were associated with both increased WMH volume (R2=0.435, p=0.015) and the presence of lacunes (R2=0.254, p=0.027). Backward stepwise elimination of individual inflammatory biomarkers for endothelial-related biomarkers revealed that VCAM-1 was significant for WMH (ß=0.063, p=0.005) and tHCY was significant for lacunes (ß=0.069, p<0.001). There was no association between any group of inflammatory biomarkers and CMBs or PVS. Systemic inflammatory biomarkers were associated with fewer DMVs (R2=0.032, p=0.006), and backward stepwise elimination of individual systemic-related inflammatory biomarkers revealed that hsCRP (ß=-0.162, p=0.007) was significant. CONCLUSION: WMH and lacunes were associated with endothelial-related inflammatory biomarkers, and fewer DMVs were associated with systemic inflammation, thus suggesting different underlying inflammatory processes and mechanisms.

Different Types of Circulatory Inflammatory Biomarkers Associated with Cerebral Arterial Atherosclerosis and Dolichoectasia.

BACKGROUND: Although inflammation is found to be related to arteriopathy pathogenesis, it is yet to be determined the distinct correlations of specific inflammatory biomarker types contributing to different cerebral large vessel diseases. We aimed to investigate the association between multiple inflammatory biomarkers and cerebral atherosclerosis and dolichoectasia in a community-based sample. METHODS: A total of 960 participants of the Shunyi study were included. A panel of 14 circulatory inflammatory biomarkers was assessed and then grouped in three sets as systemic, endothelial-related, and media-related inflammation, based on underlying different inflammatory cascades. Intracranial atherosclerotic stenosis (ICAS), dolichoectasia estimated by magnetic resonance angiography, and carotid plaques estimated by ultrasound were also performed. RESULTS: Endothelial-related inflammatory group was related to the presence of ICAS (R2 = 0.215, p = 0.024) and carotid plaques (R2 = 0.342, p = 0.013). Backward stepwise elimination showed that E-selectin was prominent (ß = 0.67, 95% CI: 0.54-0.85, p = 0.001; ß = 0.79, 95% CI: 0.68-0.93, p = 0.005). Systemic inflammatory group was associated with an increased basilar artery diameter (R2 = 0.051, p < 0.001), and backward stepwise elimination showed that IL-6 was prominent (ß = 0.07, 95% CI: 0.03-0.11, p < 0.001). CONCLUSION: Different types of inflammatory biomarkers were associated with atherosclerosis and dolichoectasia, respectively, implying dissimilar inflammatory processes. Further confirming of their distinct anti-inflammatory roles as potential therapeutic targets is warrant.

Coupling a droplet generator with conventional ESI-MS for quantitative analysis of small-volume samples.

Quantitative mass spectrometric analysis of small-volume samples (e.g., < 1 µL) has been a challenge mainly due to the difficulties with sample handling and its injection into the system for analysis. Herein we report a microfluidic analytical platform coupling a droplet generator with conventional electrospray ionization-mass spectrometry (ESI-MS) that enables multiple analyses of a µL-sized sample with sensitivity and repeatability. In an analysis by droplet generator-assisted ESI-MS (DG-ESI-MS), a sample of µL volume is pulled into a sampling capillary and its equal nL-sized portions are generated by a droplet generator and analyzed by ESI-MS at time intervals of choice. The droplet generator is made of PMMA sheets by laser engraving conveniently and at a low cost. In a study to achieve effective ESI-MS detection of water-in-oil droplets, it's found that the problem of MS signal suppression by oil can be solved by using an appropriate organic carrier with ESI-enhancing additives. The proposed DG-ESI-MS method has linear calibration curves for both adenine and phenylalanine with LODs at the sub-µM level. Application of the present analytical platform for monitoring substrate concentration changes in an enzymatic reaction solution of 3 µL is demonstrated.

A New Hybrid Lead-Free Metal Halide Piezoelectric for Energy Harvesting and Human Motion Sensing.

Hybrid organic-inorganic piezoelectrics have attracted attention due to their simple synthesis, mechanical flexibility, and designability, which have promising application potential in flexible sensing and self-powered energy harvesting devices. Although some hybrid piezoelectrics are discovered, most of their structures are limited by the perovskite-type and often contain lead. Herein, the synthesis, structure, and piezoelectric properties of a new hybrid lead-free metal halide, (BTMA)2 CoBr4 (BTMA = benzyltrimethylammonium) are reported. The experimental and theoretical results demonstrate that this material simply composed of [CoBr4 ]2- tetrahedra and BTMA+ cations exhibits significant piezoelectricity (d22 = 5.14, d25 = 12.40 pC N-1 ), low Young's and shear moduli (4.11-17.56 GPa; 1.86-7.91 GPa). Moreover, the (BTMA)2 CoBr4 /PDMS (PDMS = polydimethylsiloxane) composite thin films are fabricated and optimized. The 10% (BTMA)2 CoBr4 /PDMS-based flexible devices show attractive performance in energy harvesting with an open-circuit voltage of 19.70 V, short-circuit current of 4.24 µA, and powder density of 11.72 µW cm-2 , catching up with those of piezoelectric ceramic composites. Meanwhile, these film devices show excellent capability in accurately sensing human body motions, such as finger bending and tapping. This work demonstrates that (BTMA)2 CoBr4 and related piezoelectric lead-free halides can be promising molecular materials in modern energy and sensing applications.