Coordination Environment Engineering to Regulate the Adsorption Strength of Intermediates in Single Atom Catalysts for High-performance CO2 Reaction Reduction.

The modulation of the coordination environment of single atom catalysts (SACs) plays a vital role in promoting CO2 reduction reaction (CO2 RR). Herein, N or B doped Fe-embedded graphyne (Fe-GY), Fe-nXGYm (n = 1, 2, 3; X = N, B; m = 1, 2, 3), are employed as probes to reveal the effect of the coordination environment engineering on CO2 RR performance via heteroatom doping in SACs. The results show that the doping position and number of N or B in Fe-GY significantly affects catalyst activity and CO2 RR product selectivity. In comparison, Fe-1NGY exhibits high-performance CO2 RR to CH4 with a low limiting potential of -0.17 V, and Fe-2NGY3 is demonstrated as an excellent CO2 RR electrocatalyst for producing HCOOH with a low limiting potential of -0.16 V. With applied potential, Fe-GY, Fe-1NGY, and Fe-2NGY3 exhibit significant advantages in CO2 RR to CH4 while hydrogen evolution reaction is inhibited. The intrinsic essence analysis illustrates that heteroatom doping modulates the electronic structure of active sites and regulates the adsorption strength of the intermediates, thereby rendering a favorable coordination environment for CO2 RR. This work highlights Fe-nXGYm as outstanding SACs for CO2 RR, and provides an in-depth insight into the intrinsic essence of the promotion effect from heteroatom doping.

Eco-Friendly Cerium-Cobalt Counter-Doped Bi2Se3 Nanoparticulate Semiconductor: Synergistic Doping Effect for Enhanced Thermoelectric Generation.

Metal chalcogenides are primarily used for thermoelectric applications due to their enormous potential to convert waste heat into valuable energy. Several studies focused on single or dual aliovalent doping techniques to enhance thermoelectric properties in semiconductor materials; however, these dopants enhance one property while deteriorating others due to the interdependency of these properties or may render the host material toxic. Therefore, a strategic doping approach is vital to harness the full potential of doping to improve the efficiency of thermoelectric generation while restoring the base material eco-friendly. Here, we report a well-designed counter-doped eco-friendly nanomaterial system (~70 nm) using both isovalent (cerium) and aliovalent (cobalt) in a Bi2Se3 system for enhancing energy conversion efficiency. Substituting cerium for bismuth simultaneously enhances the Seebeck coefficient and electrical conductivity via ionized impurity minimization. The boost in the average electronegativity offered by the self-doped transitional metal cobalt leads to an improvement in the degree of delocalization of the valence electrons. Hence, the new energy state around the Fermi energy serving as electron feed to the conduction band coherently improves the density of the state of conducting electrons. The resulting high power factor and low thermal conductivity contributed to the remarkable improvement in the figure of merit (zT = 0.55) at 473 K for an optimized doping concentration of 0.01 at. %. sample, and a significant nanoparticle size reduction from 400 nm to ~70 nm, making the highly performing materials in this study (Bi2-xCexCo2x3Se3) an excellent thermoelectric generator. The results presented here are higher than several Bi2Se3-based materials already reported.

Cell-type expression and activation by light of neuropsins in the developing and mature Xenopus retina.

Photosensitive opsins detect light and perform image- or nonimage-forming tasks. Opsins such as the "classical" visual opsins and melanopsin are well studied. However, the retinal expression and functions of a novel family of neuropsins are poorly understood. We explored the developmental time-course and cell-type specificity of neuropsin (opn5, 6a, 6b, and 8) expression in Xenopus laevis by in situ hybridization and immunohistochemistry. We compared the Xenopus results with publicly available single cell RNA sequencing (scRNA-seq) data from zebrafish, chicken, and mouse. Additionally, we analyzed light-activation of neuropsin-expressing cells through induction of c-fos mRNA. opn5 and opn8 expression begins at stage 37/38 when the retinal circuits begin to be activated. Once retinal circuits connect to the brain, opn5 mRNA is distributed across multiple retinal cell types, including bipolar (~70%-75%), amacrine (~10%), and retinal ganglion (~20%) cells, with opn8 present in amacrine (~70%) and retinal ganglion (~30%) cells. opn6a and opn6b mRNAs emerge in newborn-photoreceptors (stage 35), and are colocalized in rods and cones by stage 37/38. Interestingly, in the mature larval retina (stage 43/44), opn6a and opn6b mRNAs become preferentially localized to rods and cones, respectively, while newborn photoreceptors bordering the proliferative ciliary marginal zone express both genes. In zebrafish, opn6a and opn6b are also expressed in photoreceptors, while Müller glia and amacrine cells express opn8c. Most neuropsin-expressing retinal ganglion cells display c-fos expression in response to light, as do over half of the neuropsin-expressing interneurons. This study gave a better understanding of retinal neuropsin-expressing cells, their developmental onset, and light activation.

Inducing Fe 3d Electron Delocalization and Spin-State Transition of FeN4 Species Boosts Oxygen Reduction Reaction for Wearable Zinc-Air Battery.

Transition metal-nitrogen-carbon materials (M-N-Cs), particularly Fe-N-Cs, have been found to be electroactive for accelerating oxygen reduction reaction (ORR) kinetics. Although substantial efforts have been devoted to design Fe-N-Cs with increased active species content, surface area, and electronic conductivity, their performance is still far from satisfactory. Hitherto, there is limited research about regulation on the electronic spin states of Fe centers for Fe-N-Cs electrocatalysts to improve their catalytic performance. Here, we introduce Ti3C2 MXene with sulfur terminals to regulate the electronic configuration of FeN4 species and dramatically enhance catalytic activity toward ORR. The MXene with sulfur terminals induce the spin-state transition of FeN4 species and Fe 3d electron delocalization with d band center upshift, enabling the Fe(II) ions to bind oxygen in the end-on adsorption mode favorable to initiate the reduction of oxygen and boosting oxygen-containing groups adsorption on FeN4 species and ORR kinetics. The resulting FeN4-Ti3C2Sx exhibits comparable catalytic performance to those of commercial Pt-C. The developed wearable ZABs using FeN4-Ti3C2Sx also exhibit fast kinetics and excellent stability. This study confirms that regulation of the electronic structure of active species via coupling with their support can be a major contributor to enhance their catalytic activity.

Longitudinal SARS-CoV-2 RNA wastewater monitoring across a range of scales correlates with total and regional COVID-19 burden in a well-defined urban population.

Wastewater-based epidemiology (WBE) is an emerging surveillance tool that has been used to monitor the ongoing COVID-19 pandemic by tracking SARS-CoV-2 RNA shed into wastewater. WBE was performed to monitor the occurrence and spread of SARS-CoV-2 from three wastewater treatment plants (WWTP) and six neighborhoods in the city of Calgary, Canada (population 1.44 million). A total of 222 WWTP and 192 neighborhood samples were collected from June 2020 to May 2021, encompassing the end of the first-wave (June 2020), the second-wave (November end to December 2020) and the third-wave of the COVID-19 pandemic (mid-April to May 2021). Flow-weighted 24-hour composite samples were processed to extract RNA that was then analyzed for two SARS-CoV-2-specific regions of the nucleocapsid gene, N1 and N2, using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Using this approach SARS-CoV-2 RNA was detected in 98.06% (406/414) of wastewater samples. SARS-CoV-2 RNA abundance was compared to clinically diagnosed COVID-19 cases organized by the three-digit postal code of affected individuals' primary residences, enabling correlation analysis at neighborhood, WWTP and city-wide scales. Strong correlations were observed between N1 & N2 gene signals in wastewater and new daily cases for WWTPs and neighborhoods. Similarly, when flow rates at Calgary's three WWTPs were used to normalize observed concentrations of SARS-CoV-2 RNA and combine them into a city-wide signal, this was strongly correlated with regionally diagnosed COVID-19 cases and clinical test percent positivity rate. Linked census data demonstrated disproportionate SARS-CoV-2 in wastewater from areas of the city with lower socioeconomic status and more racialized communities. WBE across a range of urban scales was demonstrated to be an effective mechanism of COVID-19 surveillance.

Can Charge-Modulated Metal-Organic Frameworks Achieve High-Performance CO2 Capture and Separation over H2 , N2 , and CH4 ?

CO2 capture and separation by using charge-modulated adsorbent materials is a promising strategy to reduce CO2 emissions. Herein, three TM-HAB (TM=Co, Ni, and Cu; HAB=hexa-aminobenzene) metal-organic frameworks (MOFs) were evaluated as charge-modulated CO2 capture and separation materials by using density functional theory and grand canonical Monte Carlo simulations. The results showed that each TM-HAB presented a high electrical conductivity and structural stability when injecting charges. The CO2 adsorption energy increased from 0.211 to 2.091 eV on Co-HAB, 0.262 to 2.119 eV on Ni-HAB, and 0.904 to 2.803 eV on Cu-HAB, respectively, with the increase in charge state from 0.0 to 3.0 e- . Co-HAB and Ni-HAB were better charge-modulated CO2 capture materials with less structure deformation based on energy decomposition analyses. The kinetic process demonstrated that considerably low energy consumptions of 0.911 and 1.589 GJ ton-1 CO2 were observed for a complete adsorption-desorption cycle on Co-HAB and Ni-HAB. All charged MOFs, especially Co-HAB and Ni-HAB, exhibited higher CO2 adsorption energies and adsorption capacities than those of H2 , N2 , and CH4 , thereby exhibiting high CO2 selectivities. Interaction analysis confirmed that the injecting charges had a more pronounced enhancement in the coulombic interactions between CO2 and MOFs. The results of this work highlight Co-HAB and Ni-HAB as promising charge-modulated CO2 capture and separation materials with controllable CO2 capture, high selectivity, and low energy consumption.

Surface Engineering of Flower-Like Ionic Liquid-Functionalized Graphene Anchoring Palladium Nanocrystals for a Boosted Ethanol Oxidation Reaction.

The development of low-cost and high-performance electrocatalyst-supporting materials is desirable and necessary for the ethanol oxidation reaction (EOR). Here, we report a facile and universal template-free approach for the first time to synthesize three-dimensional (3D) flower-like ionic liquid-functionalized graphene (IL-RGO). Then, the crystalline Pd nanoparticles were anchored on IL-RGO by a simple wet chemical growth method without a surfactant (denoted as Pd/IL-RGO). In particular, the IL is conducive to form a 3D flower-like structure. The optimized Pd/IL-RGO-2 presents a much-promoted electrocatalytic performance toward the EOR compared with commercial Pd/C catalysts, which is mainly derived from the grafted IL on RGO and the unique 3D flower-like structure. In detail, the IL can control, stabilize, and disperse the Pd nanocrystals as well as serving as the solvent and electrolyte in the microenvironment of the EOR, and the 3D flower-like structure endows the Pd/IL-RGO with high surface areas and rich opened channels, thereby kinetically accelerating the charge/mass transfers. Furthermore, density functional theory calculations reveal that the strong electronic interaction between Pd and IL-RGO generates a downshift of dcenter for Pd and thereby enhances the durability toward CO-like intermediates and electrocatalytic reaction kinetics.

In vivo liquid biopsy for glioblastoma malignancy by the AFM and LSPR based sensing of exosomal CD44 and CD133 in a mouse model.

Glioblastoma (GBM) is the fatal brain tumor in which secreted lactate enhances the expression of cluster of differentiation 44 (CD44) and the release of exosomes, cell-derived nanovesicles (30-200 nm), and therefore promotes tumor malignant progression. This study found that lactate-driven upregulated CD44 in malignant Glioblastoma cells (GMs) enhanced the release of CD44-enriched exosomes which increased GMs' migration and endothelial cells' tube formation, and CD44 in the secreted exosomes was sensitively detected by "capture and sensing" Titanium Nitride (TiN) - Nanoholes (NH) - discs immunocapture (TIC) - atomic force microscopy (AFM) and ultrasensitive TiN-NH-localized surface plasmon resonance (LSPR) biosensors. The limit of detection for exosomal CD44 with TIC-AFM- and TiN-NH-LSPR-biosensors was 5.29 × 10-1 µg/ml and 3.46 × 10-3 µg/ml in exosome concentration, respectively. Importantly, this work first found that label-free sensitive TiN-NH-LSPR biosensor could detect and quantify enhanced CD44 and CD133 levels in immunocaptured GMs-derived exosomes in the blood and the cerebrospinal fluid of a mouse model of GBM, supporting its potential application in a minimally invasive molecular diagnostic for GBM progression as liquid biopsy.

A multicenter study investigating SARS-CoV-2 in tertiary-care hospital wastewater. viral burden correlates with increasing hospitalized cases as well as hospital-associated transmissions and outbreaks.

SARS-CoV-2 has been detected in wastewater and its abundance correlated with community COVID-19 cases, hospitalizations and deaths. We sought to use wastewater-based detection of SARS-CoV-2 to assess the epidemiology of SARS-CoV-2 in hospitals. Between August and December 2020, twice-weekly wastewater samples from three tertiary-care hospitals (totaling > 2100 dedicated inpatient beds) were collected. Hospital-1 and Hospital-2 could be captured with a single sampling point whereas Hospital-3 required three separate monitoring sites. Wastewater samples were concentrated and cleaned using the 4S-silica column method and assessed for SARS-CoV-2 gene-targets (N1, N2 and E) and controls using RT-qPCR. Wastewater SARS-CoV-2 as measured by quantification cycle (Cq), genome copies and genomes normalized to the fecal biomarker PMMoV were compared to the total daily number of patients hospitalized with active COVID-19, confirmed cases of hospital-acquired infection, and the occurrence of unit-specific outbreaks. Of 165 wastewater samples collected, 159 (96%) were assayable. The N1-gene from SARS-CoV-2 was detected in 64.1% of samples, N2 in 49.7% and E in 10%. N1 and N2 in wastewater increased over time both in terms of the amount of detectable virus and the proportion of samples that were positive, consistent with increasing hospitalizations at those sites with single monitoring points (Pearson's r = 0.679, P < 0.0001, Pearson's r = 0.799, P < 0.0001, respectively). Despite increasing hospitalizations through the study period, nosocomial-acquired cases of COVID-19 (Pearson's r = 0.389, P < 0.001) and unit-specific outbreaks were discernable with significant increases in detectable SARS-CoV-2 N1-RNA (median 112 copies/ml) versus outbreak-free periods (0 copies/ml; P < 0.0001). Wastewater-based monitoring of SARS-CoV-2 represents a promising tool for SARS-CoV-2 passive surveillance and case identification, containment, and mitigation in acute- care medical facilities.

Rational Design and Effective Control of Gold-Based Bimetallic Electrocatalyst for Boosting CO2 Reduction Reaction: A First-Principles Study.

Electrochemical CO2 reduction reaction (CO2 RR) is an effective strategy converting CO2 to value-added products. Au is regarded as an efficient catalyst for electrochemical reduction of CO2 to CO, and the introduction of Pd can tune CO2 RR properties due to its strong affinity to CO. Herein, Au-Pd bimetallic electrocatalysts with different metal ratio were firstly investigated on CO2 RR mechanism by using density functional theory. The Au monolayer over Pd substrate and single Pd atom on Au(111) were found to show better CO2 RR selectivity against hydrogen evolution reaction (HER). Based on this, various single-atom catalysts on Au(111) and core-shell models with top Au monolayer were designed to study their CO2 RR performance. The results indicated that Pt, Cu, and Rh substrates below Au monolayer could enhance the activity and selectivity for CO production compared to pure Au, in which the limiting potential reduced from -0.74 to -0.63, -0.69, and -0.71 V, respectively. The single Pd embedded on Au(111) could adjust the adsorption strength, which provided an effective site to receive and further reduce CO to CH3 OH and CH4 at a low limiting potential of -0.61 V, and also avoided catalyst poisoning due to the over-strengthened CO adsorption caused by high Pd proportion on the surface. In addition, the adsorption energy of COOH was observed as a better CO2 RR reactivity descriptor than the common CO adsorption when establishing scaling relationship, which could avoid the fitting error caused by intermediate physisorption of CO.

Type II Opsins in the Eye, the Pineal Complex and the Skin of Xenopus laevis: Using Changes in Skin Pigmentation as a Readout of Visual and Circadian Activity.

The eye, the pineal complex and the skin are important photosensitive organs. The African clawed frog, Xenopus laevis, senses light from the environment and adjusts skin color accordingly. For example, light reflected from the surface induces camouflage through background adaptation while light from above produces circadian variation in skin pigmentation. During embryogenesis, background adaptation, and circadian skin variation are segregated responses regulated by the secretion of α-melanocyte-stimulating hormone (α-MSH) and melatonin through the photosensitivity of the eye and pineal complex, respectively. Changes in the color of skin pigmentation have been used as a readout of biochemical and physiological processes since the initial purification of pineal melatonin from pigs, and more recently have been employed to better understand the neuroendocrine circuit that regulates background adaptation. The identification of 37 type II opsin genes in the genome of the allotetraploid X. laevis, combined with analysis of their expression in the eye, pineal complex and skin, is contributing to the elucidation of the role of opsins in the different photosensitive organs, but also brings new questions and challenges. In this review, we analyze new findings regarding the anatomical localization and functions of type II opsins in sensing light. The contribution of X. laevis in revealing the neuroendocrine circuits that regulate background adaptation and circadian light variation through changes in skin pigmentation is discussed. Finally, the presence of opsins in X. laevis skin melanophores is presented and compared with the secretory melanocytes of birds and mammals.

Simultaneous Enhancement of Thermopower and Electrical Conductivity through Isovalent Substitution of Cerium in Bismuth Selenide Thermoelectric Materials.

It is challenging to achieve highly efficient thermoelectric materials due to the conflicts between thermopower (Seebeck coefficient) and electrical conductivity. These parameters are the core factors defining the thermoelectric property of any material. Here, we report the use of isovalent substitution as a tool to decouple the interdependency of the Seebeck coefficient and the electrical properties of cerium-doped bismuth selenide thermoelectric material. With this strategy, we can achieve a simultaneous increase in both the electrical conductivity and the Seebeck coefficient of the material by tuning the concentration of cerium doping, due to formation of neutral impurities and consequently the improvement of carrier mobility. Our theoretical calculation reveals a downward shift of the valence band with cerium concentration, which influences the thermoelectric enhancement of the synthesized materials. Finally, an order of magnitude enhancement of the figure of merit is obtained due to isovalent substitution, thus providing a new avenue for enhancing the thermoelectric performance of materials.

Electrochemical CO2 Reduction to C1 Products on Single Nickel/Cobalt/Iron-Doped Graphitic Carbon Nitride: A DFT Study.

Electrocatalytic CO2 reduction reaction (CRR) is one of the most promising strategies to convert greenhouse gases to energy sources. Herein, the CRR was applied towards making C1 products (CO, HCOOH, CH3 OH, and CH4 ) on g-C3 N4 frameworks with single Ni, Co, and Fe introduction; this process was investigated by density functional theory. The structures of the electrocatalysts, CO2 adsorption configurations, and CO2 reduction mechanisms were systematically studied. Results showed that the single Ni, Co, and Fe located from the corner of the g-C3 N4 cavity to the center. Analyses of the adsorption configurations and electronic structures suggested that CO2 could be chemically adsorbed on Co-C3 N4 and Fe-C3 N4 , but physically adsorbed on Ni-C3 N4 . The H2 evolution reaction (HER), as a suppression of CRR, was investigated, and results showed that Ni-C3 N4 , Co-C3 N4 , and Fe-C3 N4 exhibited more CRR selectivity than HER. CRR proceeded via COOH and OCHO as initial protonation intermediates on Ni-C3 N4 and Co/Fe-C3 N4 , respectively, which resulted in different C1 products along quite different reaction pathways. Compared with Ni-C3 N4 and Fe-C3 N4 , Co-C3 N4 had more favorable CRR activity and selectivity for CH3 OH production with unique rate-limiting steps and lower limiting potential.

Label-free surface plasmon resonance biosensing with titanium nitride thin film.

In this report, titanium nitride thin film synthesized with reactive magneto-sputtering technique is proposed as an alternative surface plasmon resonance sensing material. The physical and chemical natures were initially studied by atomic force microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. In virtue of white-light common-path sensing system, the wavelength modulated TiN films achieved tunable evanescent plasmonic field from 573 nm to 627 nm. The optimized TiN film with 29.8 nm thickness exhibited good differential phase sensitivity (i.e. 1.932 × 10-7 RIU) to refractive index alteration, which is comparable to the performance of gold film. We have also attained direct measurement of biotin adsorption on the TiN and monitored sub-sequential biotin-streptavidin conjugation. It was found that TiN films have significantly higher binding affinity toward biotin than that of gold in experiments, so we are able to detect biotin directly to 0.22 µg/ml (0.90 µM) in label-free manner. The adsorption mechanism of biotin on TiN(200) are also explored with periodic density functional theory (DFT) via computer simulation and it was found that the exceptional biotin-TiN affinity may be due to the stacking formation of both N-Ti and O-Ti bonds. Also, the adsorption energy of biotin-TiN was found to be - 1.85 eV, which was two times higher than that of biotin-gold. Both experimental and computational results indicate, for the first time, that the TiN film can be directly functionalized with biotin molecules, thus it serves as an alternative plasmonic material to existing gold-based SPR biosensors.

Encapsulating Co2 P@C Core-Shell Nanoparticles in a Porous Carbon Sandwich as Dual-Doped Electrocatalyst for Hydrogen Evolution.

A highly efficient and pH-universal hydrogen evolution reaction (HER) electrocatalyst with a sandwich-architecture constructed using zero-dimensional N- and P-dual-doped core-shell Co2 P@C nanoparticles embedded into a 3 D porous carbon sandwich (Co2 P@N,P-C/CG) was synthesized through a facile two-step hydrothermal carbonization and pyrolysis method. The interfacial electron transfer rate and the number of active sites increased owing to the synergistic effect between the N,P-dual-doped Co2 P@C core-shell and sandwich-nanostructured substrates. The presence of a high surface area and large pore sizes improved the mass-transfer dynamics. This nanohybrid showed remarkable electrocatalytic activity toward the HER in a wide pH range with good stability. The computational study and experiments revealed that the carbon atoms close to the N and P dopants on the shell of Co2 P@N,P-C were effective active sites for HER catalysis and that both Co2 P and the N,P dopants gave rise to an optimized binding free energy of H on the active sites.

Effects of Redox Modulation on Cell Proliferation, Viability, and Migration in Cultured Rat and Human Tendon Progenitor Cells.

Tendon healing is slow and usually results in inferior fibrotic tissue formation. Recently, application of tendon derived stem cells (TDSCs) improved tendon healing in animal studies. In a chicken model, local injection of antioxidants reduced tendon adhesion after tendon injury. An in vitro study demonstrated that supplementation of H2O2 reduced tenogenic marker expression in TDSCs. These findings suggested that the possibility of TDSCs is involved in tendon healing and the cellular activities of TDSCs might be affected by oxidative stress of the local environment. After tendon injury, oxidative stress is increased. Redox modulation might affect healing outcomes via affecting cellular activities in TDSCs. To study the effect of oxidative stress on TDSCs, the cellular activities of rat/human TDSCs were measured under different dosages of vitamin C or H2O2 in this study. Lower dose of vitamin C increased cell proliferation, viability and migration; H2O2 affected colony formation and suppressed cell migration, cell viability, apoptosis, and proliferation. Consistent with previous studies, oxidative stresses (H2O2) affect both recruitment and survival of TDSCs, while the antioxidant vitamin C may exert beneficial effects at low doses. In conclusion, redox modulation affected cellular activities of TDSCs and might be a potential strategy for tendon healing treatment.

A redox-controlled electrolyte for plasmonic enhanced dye-sensitized solar cells.

Plasmonic enhanced dye-sensitized solar cells (DSSCs) with metallic nanostructures suffer from corrosion problems, especially with the presence of the iodine/triiodide redox couple in the electrolyte. Herein, we introduce an alternative approach by compensating the corrosion with a modified liquid electrolyte. In contrast to the existing method of surface preservation for plasmonic nanostructures, the redox-controlled electrolyte (RCE) contains iodoaurate intermediates, i.e. gold(i) diiodide (AuI2-) and gold(iii) tetraiodide (AuI4-) with optimal concentrations, such that these intermediates are readily reduced to gold nanoparticles during the operation of DSSCs. As corrosion and redeposition of gold occur simultaneously, it effectively provides corrosion compensation to the plasmonic gold nanostructures embedded in the photoanode. Cycling tests of the specific amount of gold contents in the RCE of DSSCs support the fact that the dissolution and deposition of gold are reversible and repeatable. This gold deposition on the TiO2 photoanode results in forming a Schottky barrier (SB) at the metal-semiconductor interface and effectively inhibits the recombination of electron-hole pairs. Therefore, the RCE increases the short-circuit current, amplifies the open-circuit voltage, and reduces the impedance of the TiO2/dye interface. The power conversion efficiency of DSSCs was improved by 57% after incorporating the RCE.

Initial Reduction of CO2 on Pd-, Ru-, and Cu-Doped CeO2(111) Surfaces: Effects of Surface Modification on Catalytic Activity and Selectivity.

Surface modification by metal doping is an effective treatment technique for improving surface properties for CO2 reduction. Herein, the effects of doped Pd, Ru, and Cu on the adsorption, activation, and reduction selectivity of CO2 on CeO2(111) were investigated by periodic density functional theory. The doped metals distorted the configuration of a perfect CeO2(111) by weakening the adjacent Ce-O bond strength, and Pd doping was beneficial for generating a highly active O vacancy. The analyses of adsorption energy, charge density difference, and density of states confirmed that the doped metals were conducive for enhancing CO2 adsorption, especially for Cu/CeO2(111). The initial reductive dissociation CO2 → CO* + O* on metal-doped CeO2(111) followed the sequence of Cu- > perfect > Pd- > Ru-doped CeO2(111); the reductive hydrogenation CO2 + H → COOH* followed the sequence of Cu- > perfect > Ru- > Pd-doped CeO2(111), in which the most competitive route on Cu/CeO2(111) was exothermic by 0.52 eV with an energy barrier of 0.16 eV; the reductive hydrogenation CO2 + H → HCOO* followed the sequence of Ru- > perfect > Pd-doped CeO2(111). Energy barrier decomposition analyses were performed to identify the governing factors of bond activation and scission along the initial CO2 reduction routes. Results of this study provided deep insights into the effect of surface modification on the initial reduction mechanisms of CO2 on metal-doped CeO2(111) surfaces.

Direct detection of two different tumor-derived extracellular vesicles by SAM-AuNIs LSPR biosensor.

Extracellular vesicles (EVs) are abundant in various biological fluids including blood, saliva, urine, as well as extracellular milieu. Accumulating evidence has indicated that EVs, which contain functional proteins and small RNAs, facilitate intercellular communication between neighbouring cells, and are critical to maintain various physiological processes. In contrast, EV-derived toxic signals can spread out over the tissues adjacent to the injured area in certain diseases, including brain tumors and neurodegenerative disorders. This demands better characterization of EVs which can be employed for liquid biopsy clinically as well as for the study of intercellular signalling. Exosomes and microvesicles share a number of similar characteristics, but it is important to distinguish between these two types of EVs. Here, we report for the first time that our in-house developed Localized Surface Plasmon Resonance biosensor with self-assembly gold nanoislands (SAM-AuNIs) can be used to detect and distinguish exosomes from MVs isolated from A-549 cells, SH-SY5Y cells, blood serum, and urine from a lung cancer mouse model. Exosomes, compared with MVs, produced a distinguishable response to the bare LSPR biosensor without functionalization, suggesting a different biophysical interaction between exosomes and MVs with SAM AuNIs. This sensor attains the limit of detection to 0.194µg/ml, and the linear dynamic range covers 0.194-100µg/ml. This discovery not only reveals great insight into the distinctive membrane property of tumor-derived exosomes and MVs, but also facilitate the development of novel LSPR biosensors for direct detection and isolation of heterogeneous EVs.

Label-Free LSPR Detection of Trace Lead(II) Ions in Drinking Water by Synthetic Poly(mPD-co-ASA) Nanoparticles on Gold Nanoislands.

Using self-assembly gold nanoislands (SAM-AuNIs) functionalized by poly(m-phenylenediamine-co-aniline-2-sulfonic acid) (poly(mPD-co-ASA)) copolymer nanoparticles as specific receptors, a highly sensitive localized surface plasmon resonance (LSPR) optochemical sensor is demonstrated for detection of trace lead cation (Pb(II)) in drinking water. The copolymer receptor is optimized in three aspects: (1) mole ratio of mPD:ASA monomers, (2) size of copolymer nanoparticles, and (3) surface density of the copolymer. It is shown that the 95:5 (mPD:ASA mole ratio) copolymer with size less than 100 nm exhibits the best Pb(II)-sensing performance, and the 200 times diluted standard copolymer solution contributes to the most effective functionalization protocol. The resulting poly(mPD-co-ASA)-functionalized LSPR sensor attains the detection limit to 0.011 ppb toward Pb(II) in drinking water, and the linear dynamic range covers 0.011 to 5000 ppb (i.e., 6 orders of magnitude). In addition, the sensing system exhibits robust selectivity to Pb(II) in the presence of other metallic cations as well as common anions. The proposed functional copolymer functionalized on AuNIs is found to provide excellent Pb(II)-sensing performance using simple LSPR instrumentation for rapid drinking-water inspection.