Electrically addressable vesicles: Tools for dielectrophoresis metrology

Dielectrophoresis (DEP) has emerged as an important tool for the manipulation of bioparticles ranging from the submicron to the tens of microns in size. Here we show the use of phospholipid vesicle electroformation techniques to develop a new class of test particles with specifically engineered electrical propserties to enable identifiable dielectrophoretic responses in microfabricated systems. These electrically addressable vesicles (EAVs) enable the creation of electrically distinct populations of test particles for DEP. EAVs offer control of both their inner aqueous core and outer membrane properties; by encapsulating solutions of different electrolyte strength inside the vesicle and by incorporating functionalized phospholipids containing poly(ethylene glycol) (PEG) brushes attached to their hydrophilic headgroup in the vesicle membrane, we demonstrate control of the vesicles’ electrical polarizabilities. This combined with the ability to encode information about the properties of the vesicle in its fluorescence signature forms the first steps toward the development of EAV populations as metrology tools for any DEP-based microsystem.National Institutes of Health (U.S.) (Grant RR199652)National Institutes of Health (U.S.) (Grant EB005753)Merck/CSBi (Fellowship)Solomon Buchsbaum AT&T Research Fun

Connection between Telomerase Activity in PBMC and Markers of Inflammation and Endothelial Dysfunction in Patients with Metabolic Syndrome

Metabolic syndrome (MS) is a constellation of metabolic derangements associated with vascular endothelial dysfunction and oxidative stress and is widely regarded as an inflammatory condition, accompanied by an increased risk for cardiovascular disease. The present study tried to investigate the implications of telomerase activity with inflammation and impaired endothelial function in patients with metabolic syndrome. Telomerase activity in circulating peripheral blood mononuclear cells (PBMC), TNF-α, IL-6 and ADMA were monitored in 39 patients with MS and 20 age and sex-matched healthy volunteers. Telomerase activity in PBMC, TNF-α, IL-6 and ADMA were all significantly elevated in patients with MS compared to healthy volunteers. PBMC telomerase was negatively correlated with HDL and positively correlated with ADMA, while no association between TNF-α and IL-6 was observed. IL-6 was increasing with increasing systolic pressure both in the patients with MS and in the healthy volunteers, while smoking and diabetes were positively correlated with IL-6 only in the patients' group. In conclusion, in patients with MS characterised by a strong dyslipidemic profile and low diabetes prevalence, significant telomerase activity was detected in circulating PBMC, along with elevated markers of inflammation and endothelial dysfunction. These findings suggest a prolonged activity of inflammatory cells in the studied state of this metabolic disorder that could represent a contributory pathway in the pathogenesis of atherosclerosis

Label-free cell separation and sorting in microfluidic systems

Cell separation and sorting are essential steps in cell biology research and in many diagnostic and therapeutic methods. Recently, there has been interest in methods which avoid the use of biochemical labels; numerous intrinsic biomarkers have been explored to identify cells including size, electrical polarizability, and hydrodynamic properties. This review highlights microfluidic techniques used for label-free discrimination and fractionation of cell populations. Microfluidic systems have been adopted to precisely handle single cells and interface with other tools for biochemical analysis. We analyzed many of these techniques, detailing their mode of separation, while concentrating on recent developments and evaluating their prospects for application. Furthermore, this was done from a perspective where inertial effects are considered important and general performance metrics were proposed which would ease comparison of reported technologies. Lastly, we assess the current state of these technologies and suggest directions which may make them more accessible

Lead-Time Trajectory of CA19-9 as an Anchor Marker for Pancreatic Cancer Early Detection

Background & Aims There is substantial interest in liquid biopsy approaches for cancer early detection among subjects at risk, using multi-marker panels. CA19-9 is an established circulating biomarker for pancreatic cancer; however, its relevance for pancreatic cancer early detection or for monitoring subjects at risk has not been established. Methods CA19-9 levels were assessed in blinded sera from 175 subjects collected up to 5 years before diagnosis of pancreatic cancer and from 875 matched controls from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. For comparison of performance, CA19-9 was assayed in blinded independent sets of samples collected at diagnosis from 129 subjects with resectable pancreatic cancer and 275 controls (100 healthy subjects; 50 with chronic pancreatitis; and 125 with noncancerous pancreatic cysts). The complementary value of 2 additional protein markers, TIMP1 and LRG1, was determined. Results In the PLCO cohort, levels of CA19-9 increased exponentially starting at 2 years before diagnosis with sensitivities reaching 60% at 99% specificity within 0 to 6 months before diagnosis for all cases and 50% at 99% specificity for cases diagnosed with early-stage disease. Performance was comparable for distinguishing newly diagnosed cases with resectable pancreatic cancer from healthy controls (64% sensitivity at 99% specificity). Comparison of resectable pancreatic cancer cases to subjects with chronic pancreatitis yielded 46% sensitivity at 99% specificity and for subjects with noncancerous cysts, 30% sensitivity at 99% specificity. For prediagnostic cases below cutoff value for CA19-9, the combination with LRG1 and TIMP1 yielded an increment of 13.2% in sensitivity at 99% specificity ( P = .031) in identifying cases diagnosed within 1 year of blood collection. Conclusion CA19-9 can serve as an anchor marker for pancreatic cancer early detection applications

Aerosol-assisted sol–gel synthesis of mesoporous Ag–Ta–SiO₂ catalysts for the direct upgrading of ethanol to butadiene

The Lebedev process, or the direct catalytic conversion of bioethanol to butadiene, offers an up-and-coming sustainable alternative to the petrochemical route toward this high-demand C4 hydrocarbon. Since the reaction mechanism involves a cascade of dehydrogenation, hydrogen transfer and dehydration steps, a bifunctional catalyst combining both redox (for the dehydrogenation reaction) and acid (for hydrogen transfer and dehydration reactions) functionalities is required. Multi-step preparation methods are typically implemented to obtain tailored bifunctional catalysts, and one of the challenges is to balance the two functions to maximize the BD yield. Here, we disclose a straightforward, one-step, and continuous preparation method of Ta-doped SiO2 loaded with Ag nanoparticles by coupling sol–gel chemistry with aerosol processing. Combining tantalum ethoxide, silver nitrate, hydrolysed tetraethyl orthosilicate and pluronic F127 as templating agent in the aerosol process leads to mesoporous bifunctional catalysts featuring a specific surface area between 310–370 m2 g−1, a pore volume of ca. 0.5 mL g−1 and an average pore diameter of 5 nm. As attested by a variety of characterization techniques, the method leads to the homogeneous incorporation of highly dispersed tantalum species in the silica matrix, thereby creating the required acidic sites. These new catalysts have higher dehydration activity, as compared to the corresponding reference catalysts prepared by classical impregnation. Concomitantly, relatively small silver nanoparticles are stabilized (∼15 nm). The relative Ta and Ag loading can be tuned easily. In the ethanol to butadiene reaction, these aerosol-made catalysts achieve a butadiene yield of ca. 25% by optimizing the relative loadings of Ta and Ag, outcompeting the corresponding formulations prepared by impregnation

Non-hydrolytic Sol–Gel Routes to Bifunctional Cu–Ta–SiO2 Catalysts for the Upgrading of Ethanol to Butadiene

The one-step catalytic conversion of bio-based ethanol to 1,3-butadiene is an attractive way to produce this important C4 building block, to be exploited as a sustainable drop-in chemical in the tire and nylon industry. For this catalytic process, bifunctional catalysts combining both redox and acidic properties are required. Here, we leverage non-hydrolytic sol–gel (NHSG) chemistry to prepare tailored Cu–Ta–SiO2 catalysts featuring an open texture, dispersed acidic Ta sites, and small Cu nanoparticles. In the ether route, silicon tetrachloride and tantalum pentachloride undergo polycondensation reactions with diisopropyl ether as the oxygen donor. In the acetamide elimination route, silicon tetraacetate reacts with pentakis(dimethylamido)tantalum(V). In both routes, copper(II) acetylacetonate is added and trapped in a tantalosilicate matrix. Upon calcination, CuO nanoparticles form and the resulting bifunctional material develop a mesoporous texture with specific surface areas in the 650–950 m2 g–1 range, pore volumes between 0.75 and 0.90 cm3 g–1, and average pore diameters above 3 nm. With the help of NH3-TPD, FTIR, CO- and pyridine-adsorbed FTIR, XRD, XPS, and STEM-EDS, we demonstrate that the catalysts made via the acetamide elimination route show higher performance in the ethanol-to-butadiene reaction, with low selectivity in dehydration byproducts, owing to moderate Lewis acidity, smaller Cu nanoparticles, and higher active site proximity. After optimization of the Ta and Cu loadings, a butadiene productivity as high as 0.38 gBD gcat–1 h–1 is obtained, surpassing state-of-the-art catalysts with similar formulations and tested under similar reaction conditions

Broadband single cell impedance spectroscopy using maximum length sequences: theoretical analysis and practical considerations

Measurements of the dielectric (or impedance) properties of cells can be used as a general characterization and diagnostic tool. In this paper, we describe a novel impedance spectroscopy technique for the analysis of single biological cells in suspension. The technique uses maximum length sequences (MLS) for periodic excitation signal in a microfluidic impedance cytometer. The method allows multi-frequency single cell impedance measurements to be made in a short time period (ms). Spectral information is obtained in the frequency domain by applying a fast M-sequence transform (FMT) and fast Fourier transform (FFT) to the time domain response. Theoretically, the impedance is determined from the transfer function of the system when the MLS is a current excitation. The order of the MLS and sampling rate of A/D conversion are two factors that determine the bandwidth and spectral accuracy of the technique. Experimentally, the applicability of the technique is demonstrated by characterizing the impedance spectrum of red blood cells (RBCs) in a microfluidic cytometer. The impedance is measured within 1 ms at 512 discrete frequencies, evenly distributed in the range from 976.56 Hz to 500 kHz. The measured spectrum shows good agreement with simulations

Contributions of Circulating microRNAs for Early Detection of Lung Cancer

There is unmet need to develop circulating biomarkers that would enable earlier interception of lung cancer when more effective treatment options are available. Here, a set of 30 miRNAs, selected from a review of the published literature were assessed for their predictive performance in identifying lung cancer cases in the pre-diagnostic setting. The 30 miRNAs were assayed using sera collected from 102 individuals diagnosed with lung cancer within one year following blood draw and 212 controls matched for age, sex, and smoking status. The additive performance of top-performing miRNA candidates in combination with a previously validated four-protein marker panel (4MP) consisting of the precursor form of surfactant protein B (Pro-SFTPB), cancer antigen 125 (CA125), carcinoembryonic antigen (CEA) and cytokeratin-19 fragment (CYFRA21-1) was additionally assessed. Of the 30 miRNAs evaluated, five (miR-320a-3p, miR-210-3p, miR-92a-3p, miR-21-5p, and miR-140-3p) were statistically significantly (Wilcoxon rank sum test p < 0.05) elevated in case sera compared to controls, with individual AUCs ranging from 0.57–0.62. Compared to the 4MP alone, the combination of 3-miRNAs + 4MP improved sensitivity at 95% specificity by 19.1% ((95% CI of difference 0.0–28.6); two-sided p: 0.006). Our findings demonstrate utility for miRNAs for early detection of lung cancer in combination with a four-protein marker panel