A photoelectrochemical (PEC) sensor based on the poly-2,2,5,2-terthiophene (pTTh)/Cu2O heterojunction was constructed and applied for the detection of long non-coding RNA (lncRNA) TROJAN, a biomarker of triple-negative breast cancer. Cu2O and pTTh were electrodeposited in situ and sequentially onto an indium tin oxide substrate. The bandgap of the resultant type II heterojunction was measured spectroscopically and the morphology was found to effectively separate photogenerated holes from electrons. A photocurrent density as high as 250 μA cm-2 was attained, which is about three times higher than those of only pTTh or Cu2O. Owing to the close contact between pTTh and Cu2O, this PEC sensor is highly stable. Oligonucleotide probes for lncRNA can be cross-linked to carboxyl moieties of mercaptopropionic acid molecules adsorbed on pTTh/Cu2O. The desirable band structure and the high density of probe molecules collectively yielded a linear range of 0.1-10 000 pM. Our PEC sensor has been demonstrated to be amenable for detection of lncRNA markers with excellent analytical performance.

Recent advancements in signal amplifiers, such as biofunctionalized gold nanoparticles (AuNPs) have improved the surface plasmon resonance (SPR) performance. However, the correlation between the sizes of DNA-Au conjugates and the SPR chips remains elusive. We investigated how the size of AuNPs functioned with DNA detection probes (D-AuNPs) affect SPR signals in sandwich DNA hybridization assays. The effects of three sizes (5, 13, and 29 nm) of D-AuNPs with an equal surface probe density were systematically compared to delineate the relationship between signal amplification and steric hindrance. Sporadically adsorbed target DNA on sparse capture probe-coated chips led to a growth of signal amplification with larger D-AuNPs. In contrast, on dense capture probe-coated SPR chips, when the target DNA concentration was above 1.5 nM, the medium-sized 13 nm AuNPs displayed 1.7- and 1.3-fold enhancement factors than 5 nm and 29 nm ones, respectively. Our results indicate the steric hindrance disturbs the capture of D-AuNPs on dense target DNA-modified chips, rendering the surface density of captured D-AuNPs a determining factor of the sensor response. Alternatively, the sensor sensitivity to D-AuNP surface density is crucial on chips with sparse target DNA. These insights should stimulate and guide future research on surface functionalization toward SPR sensors and AuNPs.

The hallmarks of Parkinson's disease (PD) include the loss of dopaminergic neurons and formation of Lewy bodies, whereas multiple sclerosis (MS) is an autoimmune disorder with damaged myelin sheaths and axonal loss. Despite their distinct etiologies, mounting evidence in recent years suggests that neuroinflammation, oxidative stress, and infiltration of the blood-brain barrier (BBB) all play crucial roles in both diseases. It is also recognized that therapeutic advances against one neurodegenerative disorder are likely useful in targeting the other. As current drugs in clinical settings exhibit low efficacy and toxic side effects with long-term usages, the use of natural products (NPs) as treatment modalities has attracted growing attention. This mini-review summarizes the applications of natural compounds to targeting diverse cellular processes inherent in PD and MS, with the emphasis placed on their neuroprotective and immune-regulating potentials in cellular and animal models. By reviewing the many similarities between PD and MS and NPs according to their functions, it becomes evident that some NPs studied for one disease are likely repurposable for the other. A review from this perspective can provide insights into the search for and utilization of NPs in treating the similar cellular processes common in major neurodegenerative diseases.

A thin-layer flow cell of low internal volume (12 mu L) is incorporated in a flow injection analysis (FIA) system for simultaneous and real-time photoelectrochemical (PEC) immunoassay of anti-SARS-CoV-2 spike 1 (S1) and antiSARS-CoV-2 nucleocapsid (N) antibodies. Covalent linkage of S1 and N proteins to two separate polyethylene glycol (PEG)-covered gold nanoparticles (AuNPs)/TiO2 nanotube array (NTA) electrodes affords 10 consecutive analyses with surface regenerations in between. An indium tin oxide (ITO) allows visible light to impinge onto the two electrodes. The detection limits for anti-S1 and anti-N antibodies were estimated to be 177 and 97 ng mL-1, respectively. Such values compare well with those achieved with other reported methods and satisfy the requirement for screening convalescent patients with low antibody levels. Additionally, our method exhibits excellent intra-batch (RSD = 1.3%), inter-batch (RSD = 3.4%), intra-day (RSD = 1.0%), and inter-day (RSD = 1.6%) reproducibility. The obviation of an enzyme label and continuous analysis markedly decreased the assay cost and duration, rendering this method cost-effective. The excellent anti-fouling property of PEG enables ac-curacy validation by comparing our PEC immunoassays of patient sera to those of ELISA. In addition, the simultaneous detection of two antibodies holds great potential in disease diagnosis and immunity studies.

表面等离子体共振(Surface Plasmon Resonance,SPR)是利用金属与介质界面产生的一种光学现象所构建的分析技术,其在检测生物分子特异性结合方面具有免标记、高灵敏度和实时快速的特点.本文比较了常规SPR、成像SPR和SPR显微镜技术三种SPR模式的差异和应用,并着重对SPR与多通道流通体系(如微流控和流动注射分析),和以电化学为代表的其他检测技术的联用进行了概述,最后对SPR及其联用技术的应用前景进行了展望.

Ginnalin A (GA), a polyphenol from the red maple, was reported to be a potential ROS scavenger or an activator of nuclear factor erythroid-2 related factor 2 (Nrf2) in cancer cells. However, whether GA could activate Nrf2 in neuronal cells and the exact mode of action are unknown. We performed molecular docking calculations, which revealed that GA fits well into the five subpockets of the Kelch-like ECH-associated protein1 (Keap1) Kelch domain via hydrogen bonding and hydrophobic interaction. Our cytotoxicity assays demonstrate that pretreating SH-SY5Y cells with 20 μM GA effectively prevents cells from oxidative assault by 6-hydroxydopamine (6-OHDA). Fluorescence imaging indicates that upon the GA pretreatment, Nrf2 dissociates from the Keap1-Nrf2 complex and translocates into nucleus to activate the cellular antixodant system. Real-time qPCR quantification and Western blotting verified that the GA pretreatment elevates NAD(P)H quinone oxidoreductase-1 (NQO1) by more than 4.6-fold, heme oxygenase (HO-1) by about 1.2-fold, and the glutamate-cysteine ligase catalytic (GCLC) subunit by 0.7-fold. The higher antixidant protein levels, along with increased glutathione concentration, decrease intracellular reactive oxygen species and alleviate the 6-OHDA-induced oxidative damage. Silence of Nrf2 abrogates the cytoprotection of the GA pretreatment, confirming that the Keap1/Nrf2-ARE (antioxidant response element) pathway is solely responsible for the GA's biological effects. GA is a promising natural compound for sensitizing neuronal cells' antioxidative defense system to offset oxidative stress, a condition closely linked to the pathogenesis of Parkinson's disease.

A variety of compounds, including Ni-, Fe-, and Co-containing layered double hydroxides (LDHs), have been explored as catalysts for the oxygen evolution reaction (OER). However, few can meet the in...

A lead iodide perovskite solar cell has been designed using a mixed monolayer of (3-aminopropyl)trimethoxysilane (APS) and methyltrimethoxysilane (MTMS) self-assembled on a compact TiO2 layer to template the perovskite film growth. The dispersed aminopropyl groups at the surface, upon conversion to (CH2)(3)NH3+I-, form the bottommost layer of the perovskite film. The effect of the APS/MTMS compositions in the mixed monolayers on the performance of the perovskite solar cells (PSCs) was investigated by measuring the power conversion efficiency. We developed a surface modification procedure with which the [APS]/[MTMS] ratios in solution match exactly the compositions of APS and MTMS in the resultant mixed monolayers. At the [APS]/[MTMS] ratio of 50/50, the distance between two adjacent Si atoms matches well with the lattice constant of the lead iodide perovskite crystal, and the power conversion efficiency of PSCs increases from 13.2% (without the monolayer) to 17.5%. X-ray diffraction patterns suggest that the templated perovskite growth is along the (110) plane, with enhanced orientation and crystallinity. The increase in electron lifetime of the solar cell indicates that the number of photohole/electron recombination sites is reduced and charge transport at the perovskite film/TiO2 interface is facilitated.

Solar cells constructed with well-ordered polythiophene (PT) or other pi-conjugated polymer films are known to yield better photovoltaic characteristics. We recently constructed a PT-based solar cell (PTSC) wherein the photoactive PT film was grown photoelectrochemically along a dye anchor, 3-{5-[N,N-bis(4-diphenylamino)phenyl]thieno[3,2-b]thiophen-2-yl}-2-cyano-acrylic acid (C207) pre-adsorbed onto a compact TiO2 layer. In an effort to understand the effects of other important factors contributing to the PTSC performance, we compared ex-situ and in-situ doping of ordered PT films with three different alkylammonium cations, tetrabutylammonium (TBA(+)), tetraethylammonium (TEA(+)), and tetramethylammonium (TMA(+)). The PT films that have undergone such ex- and in-situ doping both show higher open-circuit voltage (V-oc) and short-circuit current density (J(sc)) than their pristine counterparts. The optimal conversion efficiency (eta) of 7.53 +/- 0.58% was achieved via in-situ PT doping with TMA(+). The incident photon-to-electron conversion efficiency (IPCE), electrochemical impedance, and electron lifetime measurements all indicate that in-situ doping is less affected by the cation size and can lead to a higher doping level than the ex-situ doping method. The IPCE also benefits from the use of a thin TiO2 layer, as more light reaches the PT film to generate photohole/electron pairs. With the combined use of a thin layer of TiO2 and an ordered PT film containing a large number of dopant ions, the photohole/electron recombination is significantly suppressed. (C) 2019 Elsevier Ltd. All rights reserved.

We recently reported on the effect of dopant sizes on the performance of polythiophene (PT)-based solar cells wherein the PT film was polymerized with 3-{5-[N,N-bis(4-diphenylamino)phenyl]thieno[3,2-b] thiophen-2-yl}-2-cyano-acrylic acid (C207) pre-adsorbed onto the electrode. Herein we utilized n- and p-doped polythiophene (PT) films as part of the solid-state dye-sensitized solar cell (ssDSSCs) based on cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylato)ruthenium(II) (N3), the most commonly used dye sensitizer. Although the structure of the N3 is different from the chain-like C207, a smooth and homogeneous PT film can still be grown photoelectrochemically into the pores and onto the surface of the N3-covered TiO2 nanoparticles. The PT films were electrochemically doped with anions (ClO4- or PF6-) and cations (tetrabutylammonium, TBA(+), or tetramethylammonium, TMA(+)). TMA(+), being smaller, leads to a higher doping level in the PT films and a power conversion efficiency of 7.57 +/- 0.33%, which is a 33% increase over that constructed with undoped PT films. However, the efficiency of the anion-doped PT films is reduced when compared to that of the undoped PT films. The N3-sensitized solar cell comprising a TMA(+)-doped PT film is 15% more efficient and costs at least 57% less than the PT-based solar cell comprising C207. This study demonstrates that the n-doped PT film can be a useful interfacial modifier, and pre-adsorbed N3 not only assists the growth of smooth PT films, but also enhances light absorption and power conversion efficiency of the resultant DSSC. (c) 2020 Elsevier Ltd. All rights reserved.

A polythiophene-based solar cell (PTSC) is constructed by photoelectrochemically polymerizing thiophene onto an ultrathin compact TiO2 layer (150 nm thick) covered with a sub-monolayer of tethered 3-{5-[ N, N-bis(4-diphenylamino)phenyl]thieno[3,2- b]thiophen-2-yl}-2-cyano-acrylic acid dye (ca. 10% coverage). The influence of morphology and thickness of the PT film on the photocurrent generated by the PTSC was investigated. With a 270 nm thick PT film and 2,2',7,7'-tetrakis( N, N-di(4-methoxyphenyl)amino)-9,9'-spirobifluorene serving as the hole-transport material, the PTSC exhibited a short-circuit current density JSC of 12.90 ± 0.63 mA/cm2, an open-circuit voltage VOC of 0.81 ± 0.01 V, and a fill factor of 0.72 ± 0.01. The high conversion efficiency (7.52 ± 0.58%) of the PTSC is attributed to the controlled PT growth along the ordered and spatially accessible dye molecules at the compact TiO2 layer, which facilitates charge transfer, prevents the hole/electron recombination, and simplifies the polymer solar cell construction with a stable and easily processable material.

Docking on the p53-binding site of murine double minute 2 (MDM2) by small molecules restores p53's tumor-suppressor function. We previously assessed 3244 FDA-approved drugs via “computational conformer selection” for inhibiting MDM2 and p53 interaction. Here, we developed a surface plasmon resonance method to experimentally confirm the inhibitory effects of the known MDM2 inhibitor, nutlin-3a, and two drug candidates predicted by our computational method. This p53/MDM2 interaction displayed a dosage-dependent weakening when MDM2 is pre-mixed with drug candidates. The inhibition efficiency order is nutlin-3a (IC50 = 97 nM) > bepridil (206 nM) > azelastine (307 nM). Furthermore, we verified their anti-proliferation effects on SJSA-1 (wild-type p53 and overexpressed MDM2), SW480 (mutated p53), and SaOs-2 (deleted p53) cancer cell lines. The inhibitory order towards SJSA-1 cell line is nutlin-3a (IC50 = 0.8 μM) > bepridil (23 μM) > azelastine (25 μM). Our experimental results are in line with the computational prediction, and the higher IC50 values from the cell-based assays are due to the requirement of higher drug concentrations to penetrate cell membranes. The anti-proliferation effects of bepridil and azelastine on the cell lines with mutated and deleted p53 implied some p53-independent anti-proliferation effects.

Cyclic voltammetry (CV) has been combined with surface plasmon resonance (SPR) for probing electrochemical deposition and redox-initiated film reorganization and conformational changes. However, the varying potential during CV scans leads to unwanted SPR background changes and complicates interpretation of SPR signals. In this work, we show that, when SPR is coupled with CV, the background correction for underpotential deposition of copper and electropolymerization of aniline is either inaccurate or difficult to perform. For accurate thickness measurements of electrodeposited films, potential-step (PS) chronoamperometry is a method of choice to combine with SPR. The theory that interprets double-layer charging is used to explain the advantage of PS chronoamperometry over CV in quantifying the thickness of electrodeposited thin films. The influence of the double-layer charging on the potential-induced SPR signal change was analyzed, and the results were used to optimize experimental parameters for PS-SPR. Overall, PS-SPR is easier to operate, simpler in data interpretation, and more accurate for the film thickness measurement.

Two six-port injector valves and one selector valve commonly used in flow injection analysis are combined with a surface plasmon resonance (SPR) instrument wherein solutions introduced from the two inlets counter-flow inside the flow cell. The system is versatile as the same or different solutions can be rapidly and repeatedly introduced to the two fluidic channels in series or in parallel. Unlike most commercial SPR instruments employing a single injector valve, solutions separately injected from the two injector valves can be readily exchanged (<1 s) between the two channels. This new method, referred to as the alternate injection mode, not only saves analysis time but also facilitates efficient and facile surface reactions for ligand immobilization and prevents immobilized species from desorbing. These advantages are demonstrated with the measurements of binding of acetazolamide (222.2 Da) to histidine-tagged human carbonic anhydrase II (his-tagged HCA). Amine-containing residues of his-tagged HCA molecules tethered at Ni-nitrilotriacetic acid (NTA) sensors were rapidly cross-linked to the underlying carboxymethylated dextran. The higher ligand densities and more stable surfaces are essential for SPR detection of small molecule binding. In a different application, microglobulin solutions of increasing concentrations were introduced for continuous binding to the preimmobilized antibody. The kinetic and affinity measurements can be conducted without performing repeated dissociation and surface regeneration reactions.

Bicinchoninic acid (BCA) is widely used for determining the valence state of copper in biological systems and quantification of the total protein concentration (BCA assay). Despite its well-known high selectivity of Cu(I) over Cu(II), the exact formation constants for Cu(I)(BCA)(2)(3-) and Cu(II)(BCA)(2)(2-) complexes remain uncertain. These uncertainties, affect the correct interpretations of the roles of copper in biological processes and the BCA assay data. By studying the voltammetric behaviors of Cu(I)(BCA)(2)(3-) and Cu(II)(BCA)(2)(2-), we demonstrate that the apparent lack of redox reaction reversibility is caused by an adsorption wave of Cu(II)(BCA)(2)(2-). With the adsorption wave identified, we found that the Cu(I)/Cu(II) selectivity of BCA is essentially identical to another popular ligand, bathocuproinedisulfonic acid (BCS). Density functional theory calculation on the geometries of Cu(I)(BCA)(2)(3-) and Cu(II)(BCA)(2)(2-) rationalizes the preferential Cu(I) binding by BCA and the strong adsorption of the Cu(II)(BCA)(2)(2-) complex at the glassy carbon electrode. Based on the shift in the standard reduction potential of free Cu(II)/Cu(I) upon binding to BCA, we affirm that the formation constants for Cu(I)(BCA)(2)(3-) and Cu(II)(BCA)(2)(2-) are 10(17.2) and 10(8.9), respectively. Therefore, BCA can be chosen among various ligands for effective and reliable studies of the copper binding affinities of different biomolecules.

Murine double minute 2 (MDM2) is an oncoprotein mediating the degradation of the tumor suppressor p53 protein. The physiological levels of MDM2 protein are closely related to malignant transformation and tumor growth. In this work, the simultaneous and label-free determination of free and p53-bound MDM2 proteins from sarcoma tissue extracts was conducted using a dual-channel surface plasmon resonance (SPR) instrument. Free MDM2 protein was measured in one fluidic channel covered with the consensus double-stranded (ds)-DNA/p53 conjugate, while MDM2 bound to p53 was captured by the consensus ds-DNA immobilized onto the other channel. To achieve higher sensitivity and to confirm specificity, an MDM2-specific monoclonal antibody (2A10) was used to recognize both the free and p53-bound MDM2 proteins. The resultant method afforded a detection limit of 0.55 pM of MDM2. The amenability of the method to the analysis of free and p53-bound MDM2 proteins was demonstrated for normal and sarcoma tissue extracts from three patients. Our data reveal that both free and total MDM2 (free and bound forms combined) proteins from sarcoma tissue extracts are of much higher concentrations than those from normal tissue extracts and the p53-bound MDM2 protein only constitutes a small fraction of the total MDM2 concentration. In comparison with enzyme-linked immunosorbent assay (ELISA), the proposed method possesses higher sensitivity, is more cost-effective, and is capable of determining free and p53-bound MDM2 proteins in clinical samples.

t‐Darpp (truncated isoform of dopamine‐ and cAMP‐regulated phosphoprotein) is a protein encoded by the PPP1R1B gene and is expressed in breast, colon, esophageal, gastric, and prostate cancers, as well as in normal adult brain striatal cells. Overexpression of t‐Darpp in cultured cells leads to increased protein kinase A activity and increased phosphorylation of AKT (protein kinase B). In HER2+ breast cancer cells, t‐Darpp confers resistance to the chemotherapeutic agent trastuzumab. To shed light on t‐Darpp function, we studied its secondary structure, oligomerization status, metal‐binding properties, and phosphorylation by cyclin‐dependent kinases 1 and 5. t‐Darpp exhibits 12% alpha helix, 29% beta strand, 24% beta turn, and 35% random coil structures. It binds calcium, but not other metals commonly found in biological systems. The T39 site, critical for t‐Darpp activation of the AKT signaling pathway, is a substrate for phosphorylation by cyclin‐dependent kinase 1 and cyclin‐dependent kinase 5. Gel filtration chromatography, sedimentation equilibrium analysis, blue native gel electrophoresis, and glutaraldehyde‐mediated cross‐linking experiments demonstrate that the majority of t‐Darpp exists as a monomer, but forms low levels (< 3%) of hetero‐oligomers with its longer isoform Darpp‐32. t‐Darpp has a large Stokes radius of 4.4 nm relative to its mass of 19 kDa, indicating that it has an elongated structure.