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The human body is a complex network of molecules,organelles, cells,tissues, and organs: an uncountable number of interactions and transformationsinterconnect all the system’s components. In addition to thesebiochemical components, biophysical components, such as pressure,flow, and morphology, and the location of all of these interactionsplay an important role in the human body. Technical difficulties havefrequently limited researchers from observing cellular biology asit occurs within the human body, but some state-of-the-art analyticaltechniques have revealed distinct cellular behaviors that occur onlyin the context of the interactions. These types of findings have inspiredbioanalytical chemists to provide new tools to better understand thesecellular behaviors and interactions. [ABSTRACT FROM AUTHOR]

The article examines the carbon-fiber microelectrodes (CFM) techniques which have illuminated the underpinnings of exocytosis. It discusses the measurement of single cell exocytosis with microelectrodes, covering history, basic instrumentation, cell types as well as the fundamental insight. It concludes that studies are currently underway to improve the methods for broader application.

Opioids are typically used for the treatment of pain related to disease or surgery. In the body, they enter the bloodstream and interact with a variety of immune and neurological cells that express the μ-, δ-, and κ-opioid receptors. One blood-borne cell-like body that is not well understood in the context of opioid interactions is the platelet. The platelet is a highly sensitive anucleate cell-like fragment responsible for maintaining hemostasis through shape change and the secretion of chemical messengers. This research characterizes platelet opioid receptors, how specific receptor agonists impact platelet exocytosis, and the role of the κ-and μ-receptors in platelet function. Platelets were found to express all three opioid receptors, but upon stimulation with their respective agonist no activation was detected. Furthermore, exposure to the opioid agonists did not impact traditional platelet secretion stimulated by thrombin, a natural platelet activator. In addition, data collected from knockout mice suggest that the opioid agonists may be interacting nonspecifically with platelets. Dark-field images revealed differences in activated platelet shape between the κ- and μ-knockout platelets and the control platelets. Finally, κ-knockout platelets showed variations in their ability to adhere and aggregate compared to control platelets. Overall, these data show that platelet function is not likely to be heavily affected by blood-borne opioids., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

In light of the importance of and challenges inherent in realizing a wearable healthcare platform for simultaneously recognizing, preventing, and treating diseases while tracking vital signs, the development of simple and customized functional devices has been required. Here, we suggest a new approach for making a stretchable light waveguide which can be combined with integrated functional devices, such as organic photodetectors (PDs) and nanowire-based heaters, for multifunctional healthcare monitoring. Controlling the reflection condition of the medium gave a solid design rule for strong light emission in our stretchable waveguides. Based on this rule, the stretchable light waveguide (up to 50% strain) made of polydimethylsiloxane was successfully demonstrated with strong emissions. We also incorporated highly sensitive organic PDs and silver nanowire-based heaters with the stretchable waveguide for the detection of vital signs, including the heart rate, deep breathing, coughs, and blood oxygen saturation. Through these multifunctional performances, we have successfully demonstrated that our stretchable light waveguide has a strong potential for multifunctional healthcare monitoring.

Flexible and stretchable electrochromic supercapacitor systems are widely considered as promising multifunctional energy storage devices that eliminate the need for an external power source. Nevertheless, the performance of conventional designs deteriorates significantly as a result of electrode/electrolyte exposure to atmosphere as well as mechanical deformations for the case of flexible systems. In this study, we suggest an all-transparent stretchable electrochromic supercapacitor device with ultrastable performance, which consists of Au/Ag core-shell nanowire-embedded polydimethylsiloxane (PDMS), bistacked WO 3 nanotube/PEDOT:PSS, and polyacrylamide (PAAm)-based hydrogel electrolyte. Au/Ag core-shell nanowire-embedded PDMS integrated with PAAm-based hydrogel electrolyte prevents Ag oxidation and dehydration while maintaining ionic and electrical conductivity at high voltage even after 16 days of exposure to ambient conditions and under application of mechanical strains in both tensile and bending conditions. WO 3 nanotube/PEDOT:PSS bistacked active materials maintain high electrochemical-electrochromic performance even under mechanical deformations. Maximum specific capacitance of 471.0 F g -1 was obtained with a 92.9% capacity retention even after 50 000 charge-discharge cycles. In addition, high coloration efficiency of 83.9 cm 2 C -1 was shown to be due to the dual coloration and pseudocapacitor characteristics of the WO 3 nanotube and PEDOT:PSS thin layer.

Binderless, additiveless Si electrode design is developed where a nanoporous ZnO matrix is coated on a Si microparticle electrode to accommodate extreme Si volume expansion and facilitate stable electrochemical cycling. The conversion reaction of nanoporous ZnO forms an ionically and electrically conductive matrix of metallic Zn embedded in Li 2 O that surrounds the Si microparticles. Upon lithiation, the porous Li 2 O/Zn matrix expands with Si, preventing extensive pulverization, while Zn serves as active material to form Li x Zn to further enhance capacity. Electrodes with a Si mass loading of 1.5 mg/cm 2 were fabricated, and a high initial capacity of ∼3900 mAh/g was achieved with an excellent reversible capacity of ∼1500 mAh/g (areal capacity ∼1.7 mAh/cm 2 ) beyond 200 cycles. A high first-cycle Coulombic efficiency was obtained owing to the conversion reaction of nanoporous ZnO, which is a notable feature in comparison to conventional Si anodes. Ex situ analyses confirmed that the nanoporous ZnO coating maintained the coalescence of SiMPs throughout extended cycling. Therefore, the Li 2 O/Zn matrix derived from conversion-reacted nanoporous ZnO acted as an effective buffer to lithiation-induced stresses from volume expansion and served as a binder-like matrix that contributed to the overall electrode capacity and stability.

Herein, a new methodology for solution-processed ZnO fabrication on Ag nanowire network electrode via combustion reaction is reported, where the amount of heat emitted during combustion was minimized by controlling the reaction temperature to avoid damaging the underlying Ag nanowires. The degree of participation of acetylacetones, which are volatile fuels in the combustion reaction, was found to vary with the reaction temperature, as revealed by thermogravimetric and compositional analyses. An optimized processing temperature of 180 °C was chosen to successfully fabricate a combustion-reacted ZnO and Ag nanowire hybrid electrode with a sheet resistance of 30 Ω/sq and transmittance of 87%. A combustion-reacted ZnO on Ag nanowire hybrid structure was demonstrated as an efficient transparent electrode and electron transport layer for the PTB7-Th-based polymer solar cells. The superior electrical conductivity of combustion-reacted ZnO, compared to that of conventional sol-gel ZnO, increased the external quantum efficiency over the entire absorption range, whereas a unique light scattering effect due to the presence of nanopores in the combustion-derived ZnO further enhanced the external quantum efficiency in the 450-550 nm wavelength range. A power conversion efficiency of 8.48% was demonstrated for the PTB7-Th-based polymer solar cell with the use of a combustion-reacted ZnO/Ag NW hybrid transparent electrode.

Nucleic acids, DNA and RNA, provide important fingerprint information for various pathogens and have significant diagnostic value; however, improved approaches are urgently needed to enable rapid detection of nucleic acids in simple point-of-care formats with high sensitivity and specificity. Here, we present a system that utilizes a series of toehold-triggered hybridization/displacement reactions that are designed to convert a given amount of RNA molecules (i.e., the analyte) into an amplified amount of signaling molecules without any washing steps or thermocycling. Fluorescent probes for signal generation were designed to consume products of the catalytic reaction in order to push the equilibrium and enhance the assay fold amplification for improved sensitivity and reaction speed. The system of toehold-assisted reactions is also modeled to better understand its performance and capabilities, and we empirically demonstrate the success of this approach with two analytes of diagnostic importance, i.e., influenza viral RNA and a micro RNA (miR-31). We also show that the amplified signal permits using a compact and cost-effective smartphone-based fluorescence reader, an important requirement toward a nucleic-acid-based point-of-care diagnostic system.

Coordination-driven self-assembly of m-bis[3-(4-pyridyl)pyrazolyl]xylene (L) and [(p-cymene) 2 Ru 2 (OO∩OO) 2 (OTf) 2 ] (A 1 ) (OO∩OO = 6,11-dioxido-5,12-naphthacenedione) in methanol resulted in a mixture of [2]catenane 1 and macrocycle 2, and self-assembly in nitromethane resulted in pure macrocycle 2, whereas the coordination-driven self-assembly of L and similar acceptors [(p-cymene) 2 Ru 2 (OO∩OO) 2 (OTf) 2 ] [OO∩OO = 5,8-dioxido-1,4-naphthoquinonnato (A 2 ); 2,5-dioxido-1,4-benzoquinonato (A 3 ); oxalato (A 4 )] resulted in the formations of monomeric macrocycles 3-5, respectively. All self-assembled macrocycles were obtained in excellent yields (>90%) as triflate salts and were fully characterized by multinuclear NMR, elemental analysis, and electrospray ionization mass spectrometry (ESI-MS). The structures of [2]catenane 1 and macrocycles 5 were confirmed by single-crystal X-ray diffraction analysis. The X-ray structure of 1 confirmed an edge-to-face interaction between the tetracene moiety in parallel-displaced π-π stacks (3.5 Å), and CH···π (2.5 Å) stabilizes the [2]catenane topology. Macrocycles 2-5 were assessed for anticancer activities using human cancer cell lines of different origins, and the macrocycle 3 was found to exhibit the best inhibitory effect and to do so in a dose-dependent manner. Further examination with the Tali apoptosis assay suggested the growth inhibitory effect of 3 involved the induction of the programmed cell death, and this suggestion was supported by observations of PARP and caspase 3 cleavage after treating cells with 3. In addition, exposure to 3 increased the expression of Bax and repressed the expression of Bcl-2, thus indicating the involvement of macrocycle 3 upstream of Bax and Bcl-2 in the apoptotic signaling pathway. Macrocycle 3 also tended to repress metastasis as evidenced by changes in the transcriptional expressions E- and N-cadherin (markers of metastasis). Furthermore, a stability assay demonstrated macrocycle 3 remained stable at high concentration.

While a range of artificial biochemical circuits is likely to play a significant role in biological engineering, one of the challenges in the field is the design of circuits that can transduce between biomolecule classes (e.g., moving beyond nucleic acid only circuits). Herein, we design a transduction mechanism whereby a protein signal is transduced into an amplified nucleic acid output using DNA nanotechnology. In this system, a protein is recognized by nucleic acid bound recognition elements to form a catalytic complex that drives a hybridization/displacement reaction on a multicomponent nucleic acid substrate, releasing multiple target single-stranded oligonucleotides in an amplified fashion. Amplification power and simple one-pot reaction conditions lead us to apply the scheme in an assay format, achieving homogeneous and rapid (∼10 min) analyte detection that is also robust (operable in whole blood and plasma). In addition, we demonstrate the assay in a microfluidic digital assay format leading to improved quantification and sensitivity approaching single-molecule levels. The present scheme we believe will have a significant impact on a range of applications from fundamental molecular interaction studies to design of artificial circuits in vivo to high-throughput, multiplexed assays for screening or point-of-care diagnostics.

Carbon-nanotube (CNT)-based textile supercapacitors with MnO2 nanoparticles have excellent power and energy densities, but MnO2 nanoparticles can be delaminated during charge-discharge cycles, which results in significant degradation in capacitance. In this study, polypyrrole conductive polymer was coated on top of MnO2 nanoparticles that are deposited on CNT textile supercapacitor to prevent delamination of MnO2 nanoparticles. An increase of 38% in electrochemical energy capacity to 461 F/g was observed, while cyclic reliability also improved, as 93.8% of energy capacity was retained over 10 000 cycles. Energy density and power density were measured to be 31.1 Wh/kg and 22.1 kW/kg, respectively. An in situ electrochemical-mechanical study revealed that polypyrrole-MnO2-coated CNT textile supercapacitor can retain 98.5% of its initial energy capacity upon application of 21% tensile strain and showed no observable energy storage capacity change upon application of 13% bending strain. After imposing cyclic bending of 750 000 cycles, the capacitance was retained to 96.3%. Therefore, the results from this study confirmed for the first time that the polypyrrole-MnO2-coated CNT textile can reliably operate with high energy and power densities with in situ application of both tensile and bending strains.

The cellular phospholipid membrane plays an important role in cell function and cell-cell communication, but its biocomplexity and dynamic nature presents a challenge for examining cellular uptake of phospholipids and the resultant effects on cell function. Platelets, small anuclear circulating cell bodies that influence a wide variety of physiological functions through their dynamic secretory and adhesion behavior, present an ideal platform for exploring the effects of exogenous phospholipids on membrane phospholipid content and cell function. In this work, a broad range of platelet functions are quantitatively assessed by leveraging a variety of analytical chemistry techniques, including ultraperformance liquid chromatography-tandem electrospray ionization mass spectrometry (UPLC-MS/MS), vasculature-mimicking microfluidic analysis, and single cell carbon-fiber microelectrode amperometry (CFMA). The relative enrichments of phosphatidylserine (PS) and phosphatidylethanolamine (PE) were characterized with UPLC-MS/MS, and the effects of the enrichment of these two phospholipids on both platelet secretory behavior and adhesion were examined. Results show that, in fact, both PS and PE influence platelet adhesion and secretion. PS was enriched dramatically and decreased platelet adhesion as well as secretion from δ-, α-, and lysosomal granules. PE enrichment was moderate and increased secretion from platelet lysosomes. These insights illuminate the critical connection between membrane phospholipid character and platelet behavior, and both the methods and results presented herein are likely translatable to other mammalian cell systems.

Neutrophils are always surrounded by/interacting with other components of the immune system; however, the current mechanistic understanding of neutrophil function is largely based on how neutrophils respond to a single chemical signal in a simplified environment. Such approaches are unable to recapitulate the in vivo microenvironment; thus, cell behavior may not fully represent the physiological behavior. Herein, we exploit a microfluidic model of the complex in vivo milieu to investigate how cell-cell interactions influence human neutrophil migration and surface marker expression. Neutrophil migration against a bacterially derived chemoattractant (formyl-met-leu-phe, fMLP), with and without preactivation by interleukins (interleukin-2 or interleukin-6), was evaluated in the presence and absence of endothelial support cells. Preactivation by interleukins or interaction with endothelial cells resulted in altered migration rates compared to naïve neutrophils, and migration trajectories deviated from the expected movement toward the fMLP signal. Interestingly, interaction with both interleukins and endothelial cells simultaneously resulted in a slight compensation in the deviation-on endothelial cells, 34.4% of untreated neutrophils moved away from the fMLP signal, while only 15.2 or 22.2% (interleukin-2-or interleukin-6-activated) of preactivated cells moved away from fMLP. Neutrophils interacting with interleukins and/or endothelial cells were still capable of prioritizing the fMLP signal over a competing chemoattractant, leukotriene B4 (LTB4). Fluorescence imaging of individual human neutrophils revealed that neutrophils treated with endothelial-cell-conditioned media showed up-regulation of the surface adhesion molecules cluster determinant 11b and 66b (CD11b and CD66b) upon stimulation. On the other hand, CD11b and CD66b down-regulation was observed in untreated neutrophils. These results leverage single cell analysis to reveal that the interaction between neutrophils and endothelial cells is involved in surface marker regulation and thus chemotaxis of neutrophils. This study brings new knowledge about neutrophil chemotaxis in the context of cell-to-cell communications, yielding both fundamental and therapeutically relevant insight.

The dynamics of neutrophil chemotaxis under competing chemoattractant gradients was studied using a microfluidic platform. This microfluidic platform, which establishes a stable and dynamic gradient of chemoattractants across a cell culture chamber, enabled the investigation of human neutrophil migration patterns in the presences of four different chemoattractants (leukotriene B(4), chemokine C-X-C motif ligands 2 and 8, and fMLP) and competing gradients of all pairwise combinations. The migration patterns for individual cells were tracked and quantitatively analyzed, and the results suggest a hierarchy among these chemoattractants of fMLP > CXCL8 > CXCL2 > leukotriene B(4). In all conditions, over 60% of neutrophils exposed to a competing gradient move toward the stronger signal though the weaker chemoattractant still influences neutrophil motility. These results yield insight about how each chemoattractant contributes to overall neutrophil chemotaxis within complex physiological environments.