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1.
J Biol Chem ; 296: 100241, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33376140

RESUMO

Conformationally distinct aggregates of the amyloid ß (Aß) peptide accumulate in brains of patients with Alzheimer's disease (AD), but the roles of the different aggregates in disease progression are not clear. We previously isolated two single-chain variable domain antibody fragments (scFvs), C6T and A4, that selectively bind different toxic conformational variants of oligomeric Aß. Here, we utilize these scFvs to localize the presence of these Aß variants in human AD brain and to demonstrate their potential as therapeutic agents for treating AD. Both A4 and C6T label oligomeric Aß in extracellular amyloid plaques, whereas C6T also labels intracellular oligomeric Aß in human AD brain tissue and in an AD mouse model. For therapeutic studies, the A4 and C6T scFvs were expressed in the AD mice by viral infection of liver cells. The scFvs were administered at 2 months of age, and mice sacrificed at 9 months. The scFvs contained a peptide tag to facilitate transport across the blood brain barrier. While treatment with C6T only slightly decreased Aß deposits and plaque-associated inflammation, it restored neuronal integrity to WT levels, significantly promoted growth of new neurons, and impressively rescued survival rates to WT levels. Treatment with A4 on the other hand significantly decreased Aß deposits but did not significantly decrease neuroinflammation or promote neuronal integrity, neurogenesis, or survival rate. These results suggest that the specific Aß conformation targeted in therapeutic applications greatly affects the outcome, and the location of the targeted Aß variants may also play a critical factor.


Assuntos
Doença de Alzheimer/genética , Peptídeos beta-Amiloides/genética , Neurônios/metabolismo , Anticorpos de Cadeia Única/genética , Doença de Alzheimer/imunologia , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/imunologia , Peptídeos beta-Amiloides/ultraestrutura , Animais , Encéfalo/imunologia , Encéfalo/metabolismo , Encéfalo/ultraestrutura , Modelos Animais de Doenças , Progressão da Doença , Humanos , Camundongos , Neurogênese/genética , Neurogênese/imunologia , Neurônios/patologia , Neurônios/ultraestrutura , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/imunologia , Conformação Proteica , Anticorpos de Cadeia Única/imunologia , Anticorpos de Cadeia Única/ultraestrutura
2.
Int J Mol Sci ; 23(24)2022 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-36555310

RESUMO

Blood-based biomarkers are needed for the early diagnosis of Alzheimer's disease (AD). We analyzed longitudinal human plasma samples from AD and control cases to identify biomarkers for the early diagnosis of AD. Plasma samples were grouped based on clinical diagnosis at the time of collection: AD, mild cognitive impairment (MCI), and pre-symptomatic (preMCI). Samples were analyzed by ELISA using a panel of reagents against nine different AD-related amyloid-ß (Aß), tau, or TDP-43 variants. Receiver operating characteristic (ROC) curves of different biomarker panels for different diagnostic sample groups were determined. Analysis of all of the samples gave a sensitivity of 92% and specificity of 76% for the diagnosis of AD. Early-stage diagnosis of AD, utilizing only the preMCI and MCI samples, identified 88% of AD cases. Using sex-biased biomarker panels, early diagnosis of AD cases improved to 96%. Using the sex-biased panels, we also identified 6 of the 25 control group cases as being at high risk of AD, which is consistent with what is expected given the advanced age of the control cases. Specific AD-associated protein variants are effective blood-based biomarkers for the early diagnosis of AD. Notably, significant differences were observed in biomarker profiles for the early detection of male and female AD cases.


Assuntos
Doença de Alzheimer , Disfunção Cognitiva , Masculino , Feminino , Humanos , Proteínas tau , Peptídeos beta-Amiloides , Disfunção Cognitiva/diagnóstico , Diagnóstico Precoce , Testes Hematológicos , Biomarcadores , Fragmentos de Peptídeos
3.
Chem Rev ; 119(5): 3349-3417, 2019 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-30821958

RESUMO

Design and modification of interfaces, always a critical issue for semiconductor devices, has become a primary tool to harness the full potential of halide perovskite (HaP)-based optoelectronics, including photovoltaics and light-emitting diodes. In particular, the outstanding improvements in HaP solar cell performance and stability can be primarily ascribed to a careful choice of the interfacial layout in the layer stack. In this review, we describe the unique challenges and opportunities of these approaches (section 1). For this purpose, we first elucidate the basic physical and chemical properties of the exposed HaP thin film and crystal surfaces, including topics such as surface termination, surface reactivity, and electronic structure (section 2). This is followed by discussing experimental results on the energetic alignment processes at the interfaces between the HaP and transport and buffer layers. This section includes understandings reached as well as commonly proposed and applied models, especially the often-questionable validity of vacuum level alignment, the importance of interface dipoles, and band bending as the result of interface formation (section 3). We follow this by elaborating on the impact of the interface formation on device performance, considering effects such as chemical reactions and surface passivation on interface energetics and stability. On the basis of these concepts, we propose a roadmap for the next steps in interfacial design for HaP semiconductors (section 4), emphasizing the importance of achieving control over the interface energetics and chemistry (i.e., reactivity) to allow predictive power for tailored interface optimization.

4.
J Am Chem Soc ; 140(33): 10504-10513, 2018 08 22.
Artigo em Inglês | MEDLINE | ID: mdl-30044630

RESUMO

The ability to manipulate quantum dot (QD) surfaces is foundational to their technological deployment. Surface manipulation of metal halide perovskite (MHP) QDs has proven particularly challenging in comparison to that of more established inorganic materials due to dynamic surface species and low material formation energy; most conventional methods of chemical manipulation targeted at the MHP QD surface will result in transformation or dissolution of the MHP crystal. In previous work, we have demonstrated record-efficiency QD solar cells (QDSCs) based on ligand-exchange procedures that electronically couple MHP QDs yet maintain their nanocrystalline size, which stabilizes the corner-sharing structure of the constituent PbI64- octahedra with optoelectronic properties optimal for solar energy conversion. In this work, we employ a variety of spectroscopic techniques to develop a molecular-level understanding of the MHP QD surface chemistry in this system. We individually target both the anionic (oleate) and cationic (oleylammonium) ligands. We find that atmospheric moisture aids the process by hydrolysis of methyl acetate to generate acetic acid and methanol. Acetic acid then replaces native oleate ligands to yield QD surface-bound acetate and free oleic acid. The native oleylammonium ligands remain throughout this film deposition process and are exchanged during a final treatment step employing smaller cations-namely, formamidinium. This final treatment has a narrow processing window; initial treatment at this stage leads to a more strongly coupled QD regime followed by transformation into a bulk MHP film after longer treatment. These insights provide chemical understanding to the deposition of high-quality, electronically coupled MHP QD films that maintain both quantum confinement and their crystalline phase and attain high photovoltaic performance.

5.
Eur J Neurosci ; 43(1): 3-16, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26332448

RESUMO

Oligomeric forms of α-synuclein and ß-amyloid are toxic protein variants that are thought to contribute to the onset and progression of Parkinson's disease (PD) and Alzheimer's disease (AD), respectively. The detection of toxic variants in human cerebrospinal fluid (CSF) and blood has great promise for facilitating early and accurate diagnoses of these devastating diseases. Two hurdles that have impeded the use of these protein variants as biomarkers are the availability of reagents that can bind the different variants and a sensitive assay to detect their very low concentrations. We previously isolated antibody-based reagents that selectively bind two different oligomeric variants of α-synuclein and two of ß-amyloid, and developed a phage-based capture enzyme-linked immunosorbent assay (ELISA) with subfemtomolar sensitivity to quantify their presence. Here, we used these reagents to show that these oligomeric α-synuclein variants are preferentially present in PD brain tissue, CSF and serum, and that the oligomeric ß-amyloid variants are preferentially present in AD brain tissue, CSF, and serum. Some AD samples also had α-synuclein pathology and some PD samples also had ß-amyloid pathology, and, very intriguingly, these PD cases also had a history of dementia. Detection of different oligomeric α-synuclein and ß-amyloid species is an effective method for identifying tissue, CSF and sera from PD and AD samples, respectively, and samples that also contained early stages of other protein pathologies, indicating their potential value as blood-based biomarkers for neurodegenerative diseases.


Assuntos
Doença de Alzheimer/diagnóstico , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Doença de Parkinson/diagnóstico , Doença de Parkinson/metabolismo , alfa-Sinucleína/metabolismo , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/sangue , Doença de Alzheimer/líquido cefalorraquidiano , Peptídeos beta-Amiloides/sangue , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Biomarcadores/sangue , Biomarcadores/líquido cefalorraquidiano , Biomarcadores/metabolismo , Ensaio de Imunoadsorção Enzimática/métodos , Feminino , Humanos , Masculino , Doença de Parkinson/sangue , Doença de Parkinson/líquido cefalorraquidiano , Fragmentos de Peptídeos/sangue , Fragmentos de Peptídeos/líquido cefalorraquidiano , Fragmentos de Peptídeos/metabolismo , Sensibilidade e Especificidade , Lobo Temporal/metabolismo , alfa-Sinucleína/sangue , alfa-Sinucleína/líquido cefalorraquidiano
6.
Langmuir ; 32(35): 8812-7, 2016 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-27504721

RESUMO

Tuning the work function of the electrode is one of the crucial steps to improve charge extraction in organic electronic devices. Here, we show that N,N-dialkyl dithiocarbamates (DTC) can be effectively employed to produce low work function noble metal electrodes. Work functions between 3.1 and 3.5 eV are observed for all metals investigated (Cu, Ag, and Au). Ultraviolet photoemission spectroscopy (UPS) reveals a maximum decrease in work function by 2.1 eV as compared to the bare metal surface. Electronic structure calculations elucidate how the complex interplay between intrinsic dipoles and dipoles induced by bond formation generates such large work function shifts. Subsequently, we quantify the improvement in contact resistance of organic thin film transistor devices with DTC coated source and drain electrodes. These findings demonstrate that DTC molecules can be employed as universal surface modifiers to produce stable electrodes for electron injection in high performance hybrid organic optoelectronics.

7.
Mol Neurobiol ; 2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38411868

RESUMO

Traumatic brain injury (TBI) increases the long-term risk of neurodegenerative diseases, including Alzheimer's disease (AD). Here, we demonstrate that protein variant pathology generated in brain tissue of an experimental TBI mouse model is similar to protein variant pathology observed during early stages of AD, and that subacute accumulation of AD associated variants of amyloid beta (Aß) and tau in the TBI mouse model correlated with behavioral deficits. Male C57BL/6 mice were subjected to midline fluid percussion injury or to sham injury, after which sensorimotor function (rotarod, neurological severity score), cognitive deficit (novel object recognition), and affective deficits (elevated plus maze, forced swim task) were assessed post-injury (DPI). Protein pathology at 7, 14, and 28 DPI was measured in multiple brain regions using an immunostain panel of reagents selectively targeting different neurodegenerative disease-related variants of Aß, tau, TDP-43, and alpha-synuclein. Overall, TBI resulted in sensorimotor deficits and accumulation of AD-related protein variant pathology near the impact site, both of which returned to sham levels by 14 DPI. Individual mice, however, showed persistent behavioral deficits and/or accumulation of toxic protein variants at 28 DPI. Behavioral outcomes of each mouse were correlated with levels of seven different protein variants in ten brain regions at specific DPI. Out of 21 significant correlations between protein variant levels and behavioral deficits, 18 were with variants of Aß or tau. Correlations at 28 DPI were all between a single Aß or tau variant, both of which are strongly associated with human AD cases. These data provide a direct mechanistic link between protein pathology resulting from TBI and the hallmarks of AD.

8.
Res Sq ; 2023 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-37205508

RESUMO

Traumatic brain injury (TBI) increases the long-term risk of neurodegenerative diseases, including Alzheimer's disease (AD). Here, we demonstrate that protein variant pathology generated in brain tissue of an experimental TBI mouse model is similar to protein variant pathology observed in human ADbrains, and that subacute accumulation of two AD associated variants of amyloid beta (Aß) and tau in the TBI mouse model correlated with behavioral deficits. Male C57BL/6 mice were subjected to midline fluid percussion injury or to sham injury, after which sensorimotor function (rotarod, neurological severity score), cognitive deficit (novel object recognition), and affective deficits (elevated plus maze, forced swim task) were assessed at different days post-injury (DPI). Protein pathology at 7, 14, and 28 DPI was measured in multiple brain regions using an immunostain panel of reagents selectively targeting different neurodegenerative disease-related variants of Aß, tau, TDP-43, and alpha-synuclein. Overall, TBI resulted in sensorimotor deficits and accumulation of AD-related protein variant pathology near the impact site, both of which returned to sham levels by 14 DPI. Individual mice, however, showed persistent behavioral deficits and/or accumulation of selected toxic protein variants at 28 DPI. Behavioral outcomes of each mouse were correlated with levels of seven different protein variants in ten brain regions at specific DPI. Out of 21 significant correlations between protein variant levels and behavioral deficits, 18 were with variants of Aß or tau. Correlations at 28 DPI were all between a single Aß or tau variant, both of which are strongly associated with human AD cases. These data provide a direct mechanistic link between protein pathology resulting from TBI and the hallmarks of AD.

9.
ACS Omega ; 8(9): 8125-8133, 2023 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-36910941

RESUMO

Perovskite (PVK) films deposited directly on n-type crystalline Si substrates were investigated by two operating modes of the surface photovoltage (SPV) method: (i) the metal-insulator-semiconductor (MIS) mode and (ii) the Kelvin probe force microscopy (KPFM). By scanning from 900 to 600 nm in the MIS mode, we consecutively studied the relatively fast processes of carrier generation, transport, and recombination first in Si, then on both sides of the PVK/Si interface, and finally in the PVK layer and its surface. The PVK optical absorption edge was observed in the range of 1.61-1.65 eV in good agreement with the band gap of 1.63 eV found from photoluminescence spectra. Both SPV methods evidenced an upward energy band bending at the PVK/n-Si interface generating positive SPV. Drift-diffusion modeling allowed us to analyze the shape of the wavelength dependence of the SPV. It was also observed that the intense illumination in the KPFM measurements induces slow SPV transients which were explained by the creation and migration of negative ions and their trapping at the PVK surface. Finally, aging effects were studied by measuring again SPV spectra after one-year storage in air, and an increase in the concentration of shallow defect states at the PVK/n-Si interface was found.

10.
Small Methods ; 7(9): e2300222, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37287372

RESUMO

The extensive use of perovskites as light absorbers calls for a deeper understanding of the interaction of these materials with light. Here, the evolution of the chemical and optoelectronic properties of formamidinium lead tri-bromide (FAPbBr3 ) films is tracked under the soft X-ray beam of a high-brilliance synchrotron source by photoemission spectroscopy and micro-photoluminescence. Two contrasting processes are at play during the irradiation. The degradation of the material manifests with the formation of Pb0 metallic clusters, loss of gaseous Br2 , decrease and shift of the photoluminescence emission. The recovery of the photoluminescence signal for prolonged beam exposure times is ascribed to self-healing of FAPbBr3 , thanks to the re-oxidation of Pb0 and migration of FA+ and Br- ions. This scenario is validated on FAPbBr3 films treated by Ar+ ion sputtering. The degradation/self-healing effect, which is previously reported for irradiation up to the ultraviolet regime, has the potential of extending the lifetime of X-ray detectors based on perovskites.

11.
Small Methods ; 7(11): e2300458, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37712197

RESUMO

Metal halide perovskites (MHPs) are semiconductors with promising application in optoelectronic devices, particularly, in solar cell technologies. The chemical and electronic properties of MHPs at the surface and interfaces with adjacent layers dictate charge transfer within stacked devices and ultimately the efficiency of the latter. X-ray photoelectron spectroscopy is a powerful tool to characterize these material properties. However, the X-ray radiation itself can potentially affect the MHP and therefore jeopardize the reliability of the obtained information. In this work, the effect of X-ray irradiation is assessed on Cs0.05 MA0.15 FA0.8 Pb(I0.85 Br0.15 )3  (MA for CH3 NH3 , and FA for CH2 (NH2 )2 ) MHP thin-film samples in a half-cell device. There is a comparison of measurements acquired with synchrotron radiation and a conventional laboratory source for different times. Changes in composition and core levels binding energies are observed in both cases, indicating a modification of the chemical and electronic properties. The results suggest that changes observed over minutes with highly brilliant synchrotron radiation are likely occurring over hours when working with a lab-based source providing a lower photon flux. The possible degradation pathways are discussed, supported by steady-state photoluminescence analysis. The work stresses the importance of beam effect assessment at the beginning of XPS experiments of MHP samples.

12.
Open Res Eur ; 3: 8, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37886228

RESUMO

A cluster of eleven research and innovation projects, funded under the same call of the EU's H2020 programme, are developing breakthrough and game-changing renewable energy technologies that will form the backbone of the energy system by 2030 and 2050 are, at present, at an early stage of development. These projects have joined forces at a collaborative workshop, entitled ' Low-TRL Renewable Energy Technologies', at the 10th Sustainable Places Conference (SP2022), to share their insights, present their projects' progress and achievements to date, and expose their approach for exploitation and market uptake of their solutions.

13.
J Chem Phys ; 136(5): 054503, 2012 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-22320747

RESUMO

Intermolecular interactions in crystalline perylene films on Au(111) have been investigated by Fourier transform infrared spectroscopy. Dimer modes of vibrations are observed in the crystalline film, in contrast to the monomer modes found for isolated perylene molecules. These dimers are formed via hydrogen bonding in the sandwich herringbone structure of the crystalline α-phase. Davydov splitting of both the monomer and the dimer modes is observed due to resonance dynamic intermolecular interaction. The splitting of monomer modes into three distinct vibrations and the occurrence of the dimer modes confirm that the film crystallizes in the α phase, which is in line with the x-ray diffraction results. The frequency shift and band broadening at elevated temperature have been attributed to the cubic and quartic anharmonic interactions.

14.
Sci Rep ; 12(1): 4520, 2022 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-35296696

RESUMO

Organic-inorganic metal halide perovskites (MHPs) have recently been receiving a lot of attention due to their newfound application in optoelectronic devices, including perovskite solar cells (PSCs) which have reached power conversion efficiencies as high as 25.5%. However, the fundamental mechanisms in PSCs, including the correlation of degradation with the excellent optoelectrical properties of the perovskite absorbers, are poorly understood. In this paper, we have explored synchrotron-based soft X-ray characterization as an effective technique for the compositional analysis of MHP thin films. Most synchrotron-based studies used for investigating MHPs so far are based on hard X-rays (5-10 keV) which include various absorption edges (Pb L-edge, I L-edge, Br K-edge, etc.) but are not suited for the analysis of the organic component in these materials. In order to be sensitive to a maximum number of elements, we have employed soft X-ray-based scanning transmission X-ray microscopy (STXM) as a spectro-microscopy technique for the characterization of MHPs. We examined its sensitivity to iodine and organic components, aging, or oxidation by-products in MHPs to make sure that our suggested method is suitable for studying MHPs. Furthermore, methylammonium triiodide with different deposition ratios of PbI2 and CH3NH3I (MAI), and different thicknesses, were characterized for chemical inhomogeneity at the nanoscale by STXM. Through these measurements, we demonstrate that STXM is very sensitive to chemical composition and homogeneity in MHPs. Thus, we highlight the utility of STXM for an in-depth analysis of physical and chemical phenomena in PSCs.

15.
RSC Adv ; 12(39): 25570-25577, 2022 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-36199324

RESUMO

We describe the investigation of metal halide perovskite layers, particularly CH3NH3PbI3 used in photovoltaic applications, by soft X-ray scanning transmission X-ray microscopy (STXM). Relevant reference spectra were used to fit the experimental data using singular value decomposition. The distribution of key elements Pb, I, and O was determined throughout the layer stack of two samples prepared by wet process. One sample was chosen to undergo electrical biasing. Spectral data shows the ability of STXM to provide relevant chemical information for these samples. We found the results to be in good agreement with the sample history, both regarding the deposition sequence and the degradation of the perovskite material.

16.
ACS Appl Mater Interfaces ; 14(30): 34228-34237, 2022 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-35245028

RESUMO

The investigation of chemical and optoelectronic properties of halide perovskite layers and associated interfaces is crucial to harness the full potential of perovskite solar cells. Depth-profiling photoemission spectroscopy is a primary tool to study the chemical properties of halide perovskite layers at different scales from the surface to the bulk. The technique employs ionic argon beam thinning that provides accurate layer thicknesses. However, there is an urgent need to corroborate the reliability of data on chemical properties of halide perovskite thin films to better assess their stability. The present study addresses the question of the Ar+ sputtering thinning on the surface chemical composition and the optoelectronic properties of the triple-cation mixed-halide perovskite by combining X-ray photoemission spectroscopy (XPS) and photoluminescence (PL) spectroscopy. First, XPS profiling is performed by Ar+ beam sputtering on a half-cell: glass/FTO/c-TiO2/perovskite. The resulting profiles show a very homogeneous and reproducible element distribution until near the buried interface; therefore, the layer is considered as quasihomogeneous all over its thickness, and the sputtering process is stable. Second, we evaluated a set of thinned perovskite layers representative of selected steps along the profile by means of PL imaging optical measurements in both steady-state and transient regimes to assess possible perturbation of the optical properties from the surface to bulk. Obtained PL spectra inside the resulting craters show no peak shift nor phase segregation. Accordingly, the transient PL measurements do not reveal any changes of the surface recombination rate in the sputtered areas. This demonstrates that there is no cumulative effect of sputtering nor drastic chemical and optoelectronic modifications, validating the determination of the in-depth composition of the perovskite layer. Combining XPS profiling with PL characterization can be a precise tool to be applied for an extensive study of the multiple layers and mixed organic/inorganic interfaces of photovoltaic devices.

17.
Neurobiol Aging ; 94: 7-14, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32497877

RESUMO

Reagents that can selectively recognize specific toxic tau variants associated with onset and progression of Alzheimer's disease (AD) and other tauopathies can be effective diagnostic and therapeutic tools. We utilized a novel atomic force microscopy-based biopanning protocol to isolate antibody fragments (single chain variable fragments, scFvs) that selectively bind tau variants present in human AD but not cognitively normal age-matched brain tissue. We identified 6 scFvs [Alzheimer's disease tau (ADT)-1 through 6] that readily distinguished between AD and control tissue and sera samples. We utilized 3 of the scFvs (ADT-2, ADT-4, and ADT-6) to analyze longitudinal plasma samples from 50 human patients, 25 patients which converted to AD during the study and 25 that remained cognitively normal. All 3 scFvs could distinguish the AD from control samples with higher tau levels in apolipoprotein E3/3 AD cases compared to apolipoprotein E3/4. Immunohistochemical analyses of human AD brain slices indicated several but not all tau variants overlapping with phosphorylated tau staining. Several reagents also showed therapeutic potential, protecting neuronal cells against AD tau-induced toxicity.


Assuntos
Doença de Alzheimer/diagnóstico , Doença de Alzheimer/metabolismo , Encéfalo/metabolismo , Fragmentos de Imunoglobulinas/isolamento & purificação , Anticorpos de Cadeia Única/isolamento & purificação , Proteínas tau/imunologia , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/etiologia , Biomarcadores/sangue , Biomarcadores/metabolismo , Feminino , Humanos , Fragmentos de Imunoglobulinas/sangue , Imuno-Histoquímica , Masculino , Fosforilação , Anticorpos de Cadeia Única/sangue , Proteínas tau/metabolismo
18.
ACS Appl Mater Interfaces ; 12(31): 34784-34794, 2020 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-32635710

RESUMO

Mixed halide perovskites have attracted a strong interest in the photovoltaic community as a result of their high power conversion efficiency and the solid opportunity to realize low-cost and industry-scalable technology. Light soaking represents one of the most promising approaches to reduce non-radiative recombination processes and thus to optimize device performances. Here, we investigate the effects of 1 sun illumination on state-of-the-art triple cation halide perovskite thin films Cs0.05(MA0.14, FA0.86)0.95 Pb (I0.84, Br0.16)3 by a combined optical and chemical characterization. Competitive passivation and degradation effects on perovskite transport properties have been analyzed by spectrally and time-resolved quantitative imaging luminescence analysis and by X-ray photoemission spectroscopy (XPS). We notice a clear improvement of the optoelectronic properties of the material, with a increase of the quasi fermi level splitting and a corresponding decrease of methylammonium MA+ for short (up to 1 h) light soaking time. However, after 5 h of light soaking, phase segregation and in-depth oxygen penetration lead to a decrease of the charge mobility.

19.
Mol Neurobiol ; 56(11): 7420-7432, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31041656

RESUMO

The amyloid ß (Aß) peptide, correlated with development of Alzheimer's disease (AD), is produced by sequential proteolytic cleavage of the amyloid precursor protein (APP) by ß- and γ-secretases. Alternative proteolytic cleavage of APP by α-secretase prevents formation of Aß peptide and produces a neuroprotective protein, a soluble fragment of APPα (sAPPα). We previously generated a single-chain variable domain antibody fragment (scFv) that binds APP at the ß-secretase cleavage site and blocks cleavage of APP (iBsec1), and a second scFv which has been engineered to have α-secretase-like activity that increases α-secretase cleavage of APP (Asec1a) and showed that a bispecific antibody (Diab) combining both iBsec1 and Asec1a constructs protects mammalian cells from oxidative stress. Here, we show that the diabody is an effective therapeutic agent in a mouse model of AD. An apolipoprotein B (ApoB) binding domain peptide was genetically added to the diabody to facilitate transfer across the blood-brain barrier, and a recombinant human adeno-associated virus 2/8 (rAAV2/8) was used as a vector to express the gene constructs in a APP/PS1 mouse model of AD. The diabody increased levels of sAPPα, decreased Aß deposits and levels of oligomeric Aß, increased neuronal health as indicated by MAP2 and synaptophysin staining, increased hippocampal neurogenesis, and most importantly dramatically increased survival rates compared with untreated mice or mice treated only with the ß-secretase inhibitor. These results indicate that altering APP processing to inhibit ß-site activity while simultaneously promoting α-secretase processing provides substantially increased neuronal benefits compared with inhibition of ß-secretase processing alone and represents a promising new therapeutic approach for treating AD.


Assuntos
Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Anticorpos Biespecíficos/farmacologia , Neurônios/metabolismo , Doença de Alzheimer/metabolismo , Amiloide/metabolismo , Animais , Encéfalo/metabolismo , Espinhas Dendríticas/efeitos dos fármacos , Espinhas Dendríticas/metabolismo , Modelos Animais de Doenças , Feminino , Gliose/patologia , Células HEK293 , Humanos , Camundongos Endogâmicos C57BL , Neurogênese/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Presenilina-1/metabolismo , Anticorpos de Cadeia Única/metabolismo , Solubilidade , Sinapses/metabolismo
20.
Sci Adv ; 5(1): eaas9311, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30746434

RESUMO

Methylammonium lead iodide (MAPbI3) exhibits exceptional photovoltaic performance, but there remains substantial controversy over the existence and impact of ferroelectricity on the photovoltaic response. We confirm ferroelectricity in MAPbI3 single crystals and demonstrate mediation of the electronic response by ferroelectric domain engineering. The ferroelectric response sharply declines above 57°C, consistent with the tetragonal-to-cubic phase transition. Concurrent band excitation piezoresponse force microscopy-contact Kelvin probe force microscopy shows that the measured response is not dominated by spurious electrostatic interactions. Large signal poling (>16 V/cm) orients the permanent polarization into large domains, which show stabilization over weeks. X-ray photoemission spectroscopy results indicate a shift of 400 meV in the binding energy of the iodine core level peaks upon poling, which is reflected in the carrier concentration results from scanning microwave impedance microscopy. The ability to control the ferroelectric response provides routes to increase device stability and photovoltaic performance through domain engineering.

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