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1.
Int J Nanomedicine ; 16: 2283-2295, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33776433

RESUMO

Background: Paclitaxel (PTX) has interesting anticancer activity. However, it is insoluble in water, which seriously hinders its use in clinical. Superparamagnetic iron oxide nanoparticles (SPIONs) are used as an ideal drug delivery system. Therefore, we proposed a folic acid (FA) targeting drug-loaded SPIONs to reduce its adverse reaction. Methods: To improve the hydrophilicity of PTX, the structure of PTX was modified by succinic anhydride to obtain 2'-succinate paclitaxel (SPTX). FA conjugated Polyethylene glycol (PEG)/polyethyleneimine (PEI)-SPIONs SPTX-loaded nanoparticles (SPTX@FA@PEG/PEI-SPIONs) were prepared by solvent volatilization and hydrogen bond adsorption, and the nano-formulation was optimized by response surface methodology (RSM). The characteristics, antitumor effect in vitro, pharmacokinetics, and biodistribution of SPTX@FA@PEG/PEI-SPIONs were evaluated. Results: SPTX was successfully loaded on the surface of FA@PEG/PEI-SPIONs. The formation of SPTX@FA@PEG/PEI-SPIONs was exhibited water-dispersive monodispersity with high stability by RSM, and dynamic light scattering (DLS) was 178.1±3.12 nm, particle size observed in the transmission electron microscope (TEM) was 13.01±1.10 nm, and the encapsulation efficiency (EE) and loading efficiency (LE) were 81.1±1.66% and 14.8±1.46%, respectively. It enhanced the stability in normal physiological condition, accelerated drug release at tumorous pH, and preferentially prolonged the circulation time. In vitro, the SPTX@FA@PEG/PEI-SPIONs significantly targeted to folate receptor (FR) positive cancers cell (HNE-1) via the receptor-ligand mediated pathway, resulting in effective cytotoxic activity. Pharmacokinetic results demonstrated that SPTX@FA@PEG/PEI-SPIONs (t1/2=3.41 h) had longer than free SPTX or PTX (t1/2=1.67 h) in rats in vivo. Tissue distribution studies showed that SPTX@FA@PEG/PEI-SPIONs were present at high levels in the liver and help in targeting the folate receptors present on the kidneys. Conclusion: These results suggest that SPTX@FA@PEG/PEI-SPIONs offer a highly promising approach to control drug release, improve drug pharmacokinetics and actively target the nasopharyngeal carcinoma.


Assuntos
Ácido Fólico/química , Paclitaxel/farmacologia , Animais , Antineoplásicos/química , Antineoplásicos/farmacologia , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Liberação Controlada de Fármacos , Humanos , Iminas/química , Concentração Inibidora 50 , Carcinoma Nasofaríngeo/tratamento farmacológico , Carcinoma Nasofaríngeo/patologia , Paclitaxel/sangue , Paclitaxel/farmacocinética , Paclitaxel/uso terapêutico , Tamanho da Partícula , Polietilenoglicóis/química , Polietilenos/química , Ratos , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Succinatos/química , Distribuição Tecidual/efeitos dos fármacos
2.
AAPS J ; 23(2): 44, 2021 03 14.
Artigo em Inglês | MEDLINE | ID: mdl-33719006

RESUMO

Anthracyclines are a class of chemotherapy drugs that are highly effective for the treatment of human cancers, but their clinical use is limited by associated dose-dependent cardiotoxicity. The precise mechanisms by which individual anthracycline induces cardiotoxicity are not fully understood. Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are emerging as a physiologically relevant model to assess drugs cardiotoxicity. Here, we describe an assay platform by coupling hiPSC-CMs and impedance measurement, which allows real-time monitoring of cardiomyocyte cellular index, beating amplitude, and beating rate. Using this approach, we have performed comparative studies on a panel of four anthracycline drugs (doxorubicin, epirubicin, idarubicin, and daunorubicin) which share a high degree of structural similarity but are associated with distinct cardiotoxicity profiles and maximum cumulative dose limits. Notably, results from our hiPSC-CMs impedance model (dose-dependent responses and EC50 values) agree well with the recommended clinical dose limits for these drugs. Using time-lapse imaging and RNAseq, we found that the differences in anthracycline cardiotoxicity are closely linked to extent of cardiomyocyte uptake and magnitude of activation/inhibition of several cellular pathways such as death receptor signaling, ROS production, and dysregulation of calcium signaling. The results provide molecular insights into anthracycline cardiac interactions and offer a novel assay system to more robustly assess potential cardiotoxicity during drug development.

3.
AAPS J ; 23(2): 39, 2021 03 07.
Artigo em Inglês | MEDLINE | ID: mdl-33677681

RESUMO

Immune checkpoint inhibitors (ICIs) are considered a new standard-of-care across many cancer indications. This review provides an update on ICIs approved by the Food and Drug Administration (FDA), with focus on monoclonal antibodies that target the programmed cell death 1 (PD-1) or its ligand, PD-1 ligand 1 (PD-L1), including information on their clinical indications and associated companion diagnostics. The information is further discussed with strategies for identifying predictive biomarkers to guide the clinical use of PD-1/PD-L1-targeted therapies.

4.
Nanotechnology ; 32(14): 145710, 2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33438583

RESUMO

There are unrevealed factors that bring about the performance variations of resistive switching devices. In this work, Pt/CeO x /Pt devices prepared by magnetron sputtering showed rectification in their asymmetrical current-voltage (I-V) curves during voltage sweeps. X-ray photoelectron spectroscopy showed that the deposited CeO x film had an inhomogeneous composition, and more oxygen vacancies existed in CeO x near the top electrode. The asymmetrical resistance change of the Pt/CeO x /Pt devices can be explained by the presence of more charged oxygen vacancies in CeO x near the top electrode, along with the Schottky conduction mechanism. This work reveals that the compositional inhomogeneity is inevitable in the magnetron sputtering of oxide targets like CeO2 and can be an important source of device-to-device and cycle-to-cycle variations of memristors.

5.
ISA Trans ; 2021 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-33446341

RESUMO

This article focuses on observer-based state feedback H∞ control for a jacket structure against DoS attacks and external wave loads. First, a networked model of the structure is formulated as a switched delay system, in which DoS attacks and network-induced delays are considered simultaneously. A matching switched observer is developed for estimating states of the networked jacket structure system. Then, some new sufficient conditions are provided for the observer-based networked H∞ controller for the resultant switched system. Finally, it is shown from several case studies that the provided mechanism can maintain desired performance of the jacket structure against attacks and wave loads. In addition, the developed control schemes can save the control cost significantly.

6.
Nanotechnology ; 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33321474

RESUMO

There are unrevealed factors that bring about the performance variations of resistive switching devices. In this work, Pt/CeOx/Pt devices prepared by magnetron sputtering showed rectification in their asymmetrical current-voltage (I-V) curves during voltage sweeps. X-ray photoelectron spectroscopy (XPS) showed that the deposited CeOx film had an inhomogeneous composition, and more oxygen vacancies existed in CeOx near the top electrode. The asymmetrical resistance change of the Pt/CeOx/Pt devices can be explained by the presence of more charged oxygen vacancies in CeOx near the top electrode, along with the Schottky conduction mechanism. This work reveals that the compositional inhomogeneity is inevitable in the magnetron sputtering of oxide targets like CeO2 and can be an important source of device-to-device and cycle-to-cycle variations of memristors.

7.
Drug Resist Updat ; 53: 100733, 2020 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-33161277

RESUMO

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), represents an unprecedented challenge to global public health. At the time of this review, COVID-19 has been diagnosed in over 40 million cases and associated with 1.1 million deaths worldwide. Current management strategies for COVID-19 are largely supportive, and while there are more than 2000 interventional clinical trials registered with the U.S. National Library of Medicine (clinicaltrials.gov), results that can clarify benefits and risks of candidate therapies are only gradually becoming available. We herein describe recent advances in understanding SARS-CoV-2 pathobiology and potential therapeutic targets that are involved in viral entry into host cells, viral spread in the body, and the subsequent COVID-19 progression. We highlight two major lines of therapeutic strategies for COVID-19 treatment: 1) repurposing the existing drugs for use in COVID-19 patients, such as antiviral medications (e.g., remdesivir) and immunomodulators (e.g., dexamethasone) which were previously approved for other disease conditions, and 2) novel biological products that are designed to target specific molecules that are involved in SARS-CoV-2 viral entry, including neutralizing antibodies against the spike protein of SARS-CoV-2, such as REGN-COV2 (an antibody cocktail), as well as recombinant human soluble ACE2 protein to counteract SARS-CoV-2 binding to the transmembrane ACE2 receptor in target cells. Finally, we discuss potential drug resistance mechanisms and provide thoughts regarding clinical trial design to address the diversity in COVID-19 clinical manifestation. Of note, preventive vaccines, cell and gene therapies are not within the scope of the current review.

8.
Mol Biol Evol ; 2020 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-32986826

RESUMO

Guenons (tribe Cercopithecini) are the most widely distributed non-human primate in the tropical forest belt of Africa and show considerable phenotypic, taxonomic, and ecological diversity. However, genomic information for most species within this group is still lacking. Here, we present a high-quality de novo genome (total 2.90 Gb, contig N50 equal to 22.7 Mb) of the mona monkey (Cercopithecus mona), together with genome resequencing data of 13 individuals sampled across Nigeria. Our results showed differentiation between populations from East and West of the Niger River ∼84 thousands years ago and potential ancient introgression in the East population from other mona group species. The PTPRK, FRAS1, BNC2, and EDN3 genes related to pigmentation displayed signals of introgression in the East population. Genomic scans suggest that immunity genes such as AKT3 and IL13 (possibly involved in simian immunodeficiency virus defense), and G6PD, a gene involved in malaria resistance, are under positive natural selection. Our study gives insights into differentiation, natural selection and introgression in guenons.

9.
Sci Rep ; 10(1): 13096, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32753716

RESUMO

Recent reports have shown that intracellular, (super)paramagnetic ferritin nanoparticles can gate TRPV1, a non-selective cation channel, in a magnetic field. Here, we report the effects of differing field strength and frequency as well as chemical inhibitors on channel gating using a Ca2+-sensitive promoter to express a secreted embryonic alkaline phosphatase (SEAP) reporter. Exposure of TRPV1-ferritin-expressing HEK-293T cells at 30 °C to an alternating magnetic field of 501 kHz and 27.1 mT significantly increased SEAP secretion by ~ 82% relative to control cells, with lesser effects at other field strengths and frequencies. Between 30-32 °C, SEAP production was strongly potentiated 3.3-fold by the addition of the TRPV1 agonist capsaicin. This potentiation was eliminated by the competitive antagonist AMG-21629, the NADPH oxidase assembly inhibitor apocynin, and the reactive oxygen species (ROS) scavenger N-acetylcysteine, suggesting that ROS contributes to magnetogenetic TRPV1 activation. These results provide a rational basis to address the heretofore unknown mechanism of magnetogenetics.

10.
Angew Chem Int Ed Engl ; 59(41): 17864-17871, 2020 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-32602223

RESUMO

The visualization of temporal and spatial changes in the intracellular environment has great significance for chemistry and bioscience research. Mass spectrometry imaging (MSI) plays an important role because of its unique advantages, such as being label-free and high throughput, yet it is a challenge for laser-based techniques due to limited lateral resolution. Here, we develop a simple, reliable, and economic nanoscale MSI approach by introducing desorption laser with a micro-lensed fiber. Using this integrated platform, we achieved 300 nm resolution MSI and successfully visualized the distribution of various small-molecule drugs in subcellular locations. Exhaustive dynamic processes of anticancer drugs, including releasing from nanoparticle carriers entering nucleus of cells, can be readily acquired on an organelle scale. Considering the simplicity and universality of this nanoscale desorption device, it could be easily adapted to most of laser-based mass spectrometry applications.

11.
Sci Total Environ ; 739: 139760, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32544674

RESUMO

To examine the temporal variation of macrobenthic community zonation over nearly 60 years and the effects of latitude and depth in the southern Yellow Sea and East China Sea, a total of 1386 box-corer samples from four large spatial scale studies during 1958-1959, 2000-2004, 2011-2013 and 2014-2016 period, respectively, were compiled. A total of 26, 14, 13 and 18 communities were identified, respectively during the four periods with the same analytical method. The Yellow Sea Cold Water Mass (YSCWM) community, restricted to the 34°N latitude in the south and 50 m isobaths in the west, varied little in its spatial pattern over nearly 60 years, while other communities did not. The representative species in the YSCWM community changed from the polychaetes to the brittle stars during 1958-2016. However, in other large spatial scale communities except the YSCWM community, the representative species changed from the echinoderms, nemerteans or crustaceans to the polychaetes. For the revisited locations across studies, significant temporal and spatial variations in community structure at both species and family levels were detected. Macrobenthic species with high consecutive contributions to the community similarity were significantly influenced by latitude, depth, temperature and salinity, among which latitude and depth were the first two most significant environmental variables. Species diversity increased from 32 to 37°N during 1958-1959, but decreased during 2014-2016. It seems that the latitude of 32°N is an ecological barrier for macrobenthic community and diversity, but its effects weakened from 1958 to 2016. Species diversity roughly showed a first increasing then decreasing trend with the increase of the water depth in the southern Yellow Sea and East China Sea.


Assuntos
Crustáceos , Água do Mar , Animais , China , Ecossistema , Oceanos e Mares , Salinidade
12.
Mar Pollut Bull ; 153: 111020, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32275566

RESUMO

The main environmental variables of bottom seawater and macrobenthic invertebrates were investigated from February 2015 to January 2016 to evaluate the benthic ecological status in adjacent areas of the Yangtze River Estuary, China. Diverse ecological assessment results were given by the AZTI Marine Biotic Index (AMBI), multivariate-AMBI (M-AMBI) and benthic opportunistic polychaetes amphipods (BOPA) index, showing that the M-AMBI was the most suitable in the study area. A clear spatial distribution pattern related to the distance from the estuary and the coasts was found both for the benthic ecological status and the eutrophication-related bottom seawater environmental variables, indicating that the study area was under eutrophication pressure. Two major disturbed regions (one was east of the Yangtze River Estuary, and the other was east of Zhejiang Province) were discovered, which was probably mainly caused by the Changjiang Diluted Water (CDW). No significant seasonal changes were found in the ecological status.


Assuntos
Anfípodes , Monitoramento Ambiental , Estuários , Animais , China , Ecossistema , Invertebrados , Rios
13.
Mol Phylogenet Evol ; 148: 106789, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32173414

RESUMO

The genus Amolops ("torrent frogs") is one of the most species-rich genera in Ranidae, with 59 recognized species. This genus currently includes six species groups diagnosed mainly by morphology. Several recent molecular studies indicated that the classification of species groups within Amolops remains controversial, and key nodes in the phylogeny have been inadequately resolved. In addition, the diversity of Amolops remains poorly understood, especially for those from incompletely sampled regions. Herein, we investigate species-level diversity within the genus Amolops throughout southern China and Southeast Asia, and infer evolutionary relationships among the species using mtDNA data (16S, COI, and ND2). Molecular analyses indicate nine unnamed species, mostly distributed in the Himalayas. We then utilized anchored hybrid enrichment to generate a dataset representing the major mitochondrial lineages to resolve phylogenetic relationships, biogeography, and pattern of species diversification. Our resulting phylogeny strongly supports the monophyly of four previously identified species groups (the A. ricketti, A. daiyunensis, A. hainanensis, and A. monticola groups), but paraphyly for the A. mantzorum and A. marmoratus groups, as previously defined. We erect one new species group, the A. viridimaculatus group, and recognize Dubois' (1992) subgenus Amo as the A. larutensis species group. Biogeographic analysis suggests that Amolops originated on the Indo-Burma/Thai-Malay Peninsula at the Eocene/Oligocene boundary, and dispersed outward, exemplifying a common pattern observed for the origin of Asian biodiversity. The early divergence within Amolops coincides with the Himalayan uplift and the lateral extrusion of Indochina at the Oligocene/Miocene boundary. Our results show that paleoclimatic and geomorphological events have profoundly influenced the patterns of lineage diversification within Amolops.


Assuntos
Biodiversidade , Núcleo Celular/genética , DNA Mitocondrial/genética , Filogenia , Filogeografia , Ranidae/genética , Animais , Ásia Sudeste , Sequência de Bases , Teorema de Bayes , Análise Espaço-Temporal , Especificidade da Espécie
14.
Biomed Mater ; 15(4): 045014, 2020 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-32069444

RESUMO

Efficient attachment of magnetic nanoparticles to cell membranes plays an important role in the activation of cell membrane channels. Streptavidin (SA) was successfully modified to Poly (ethylene imine) (PEI)-superparamagnetic iron oxide nanoparticles (SPIONs) to form SA/PEI-SPIONs, which have high colloidal stability and low cytotoxicity. The SA/PEI-SPIONs were incubated with PC-12 cells which had first been cultured in a Roswell Park Memorial Institute medium 1640 containing 0.2 mg l-1 biotin for 12 h. The cells were observed by transmission electron microscopy, and the nanoparticles were clearly attached on the cell membrane, which can be attributed to the specific binding between the SA and biotin sites on the cell surface. This work provides a simple way to attach SA-modified nanoparticles on the membranes of cells by only culturing cells in a biotin-containing medium. This work makes possible biomedical applications that require nanoparticles to target cell membranes.

15.
ACS Appl Mater Interfaces ; 12(5): 6788-6792, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31913014

RESUMO

Effective ultraviolet light-emitting diodes (LEDs) were fabricated by clamping the n-ZnO films on the top of p-hBN/p-GaN/sapphire substrates. An ultraviolet emission originating from ZnO was measured from the diode under a forward bias, the electroluminescence (EL) spectra of which show a peak wavelength of ∼376 nm with a narrow full-width at half maximum of ∼12 nm. Compared with the reference diode fabricated by directly growing n-ZnO on the p-hBN substrates using metal-organic chemical vapor deposition, the proposed diode showed a dramatic increment of the EL intensity; meanwhile, its emission onset lowered down considerably. The improved optical property of the proposed LED is mainly ascribed to suppressing the formation of the BNO-related layer at the n-ZnO/p-hBN interface. The present work provides a simple and feasible approach for developing advanced ZnO-based optoelectronic devices.

16.
J Mater Chem B ; 8(4): 758-766, 2020 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-31897462

RESUMO

Effective attachment of magnetic nanoparticles to neuronal membranes has far-reaching significance in activating ion channels and treating neurodegenerative diseases. Superparamagnetic iron oxide nanoparticles (SPIONs) synthesized by the polyol pyrolysis method have the advantages of rich surface functional groups, excellent magnetic properties, controllable particle size and water dispersibility. We propose that perfusion of biotin into the targeted brain area should be initially performed because it tends to be adsorbed by cell membranes, followed by injection of streptavidin (SA)-modified SPIONs into the same area of the brain. By means of the strong binding force between SA and biotin, the SPIONs may subsequently adhere to the cell surfaces in the brain area. In this work, fluorescein isothiocyanate-streptavidin (FITC-SA) was modified on the surface of polyethylene imine (PEI)-SPIONs by the EDC-NHS method and stereotaxically injected into the biotin-supplemented substantia nigra of mice. The combination of fluorescence detection with transmission electron microscopy (TEM) confirmed that FITC-SA/PEI-SPIONs adhered to neuronal membranes in the substantia nigra of mice 24 h after injection. The results show that our strategy can promote the attachment of SPIONs to neuronal membranes.

17.
MAbs ; 12(1): 1685814, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31774346

RESUMO

Therapeutic monoclonal antibodies (mAbs) are commonly administered to patients through intravenous (IV) infusion, which involves diluting the medication into an infusion solution (e.g., saline and 5% dextrose). Using the wrong diluent can cause product aggregation, which may compromise patient safety. We and others have shown that Herceptin® (trastuzumab) and Avastin® (bevacizumab) undergo rapid aggregation upon mixing with dextrose and human plasma in vitro. In this study, we evaluated the compatibility of a panel of 11 therapeutic mAbs with dextrose or saline and human serum. These mAbs were randomly selected for their distinct formulations and IgG isotypes (IgG1, IgG2, IgG4, and Fc-fusion protein). All the mAbs appeared to be compatible with saline and human serum. However, mAbs that were formulated at acidic pH (≤ 6.5) exclusively formed insoluble aggregates upon mixing with dextrose and serum. Such aggregation was not detected for the mAbs that are at neutral pH (7.2-7.5) or in buffers containing sodium chloride. Mass spectrometric analysis revealed that the insoluble aggregates were composed of mAb molecules and several serum proteins (e.g., complement proteins, apolipoprotein, fibronectin) that are characterized by an isoelectric point of pH 5.4-6.7. At proximate pH to the isoelectric point values, those abundant serum proteins appeared to undergo isoelectric precipitation with mAb molecules. Our observations highlight a potential risk of protein aggregation at the blood-IV interface if a diluent is incompatible with a specific mAb formulation. This information has implications in guiding the design of product formulations and the selection of the right diluent for intravenous infusion of therapeutic mAbs.Abbreviations: ADC: antibody-drug conjugate; D5W: 5% dextrose in water; IM: intramuscular; IV: intravenous; LC-MS/MS: liquid chromatography-tandem mass spectrometry; mAb: monoclonal antibody; SC: subcutaneous; pI: isoelectric point.

18.
ACS Chem Neurosci ; 11(2): 197-204, 2020 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-31867955

RESUMO

Localizing nanoparticles on or near cell membranes in vivo remains a big challenge. We present a cell membrane targeting complex based on chondroitin sulfate (CS)-conjugated superparamagnetic iron oxide nanoparticles (CS-SPIONs). After SPIONs were injected into the substantia nigra of rats, the subcellular distributions of SPIONs with and without CS modification have been evaluated by transmission electron microscopy (TEM) analysis. CS-SPIONs exhibited low toxicity and low endocytosis and were highly distributed in the extracellular spaces nearing neuronal cell bodies and synapses. This can be attributed to the nature of CS, one of the main components of perineuronal nets with the tendency to surround neuronal cell bodies, dendrites, and synapses. It is expected that CS-SPIONs have a great potential for therapies requiring targeting of or approach to cell membranes.

19.
J Nanosci Nanotechnol ; 20(4): 2018-2024, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31492207

RESUMO

Poly(ethylene glycol) (PEG)/poly(ethylene imine) (PEI) modified superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized by the thermal decomposition of iron (III) acetylacetonate (Fe(acac)3) in PEG containing PEI. Transferrin (Tf) was employed to functionalize SPIONs. The potential of Tf-SPIONs as brain magnetic resonance (MR) imaging contrast agents was explored by using Kunming mice as an animal model. The in vivo experiments revealed that Tf-SPIONs exhibited an enhanced contrast time as compared with the PEG-SPIONs and PEG/PEI-SPIONs. Tf-SPIONs exhibit promising potential for bioimaging applications because of their advantages of dispersibility in water, low cytotoxicity and long circulation time in blood.

20.
IEEE Trans Cybern ; 50(3): 946-956, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30346302

RESUMO

This paper is concerned with passivity of a class of delayed neural networks. In order to derive less conservative passivity criteria, two Lyapunov-Krasovskii functionals (LKFs) with delay-dependent matrices are introduced by taking into consideration a second-order Bessel-Legendre inequality. In one LKF, the system state vector is coupled with those vectors inherited from the second-order Bessel-Legendre inequality through delay-dependent matrices, while no such coupling of them exists in the other LKF. These two LKFs are referred to as the coupled LKF and the noncoupled LKF, respectively. A number of delay-dependent passivity criteria are derived by employing a convex approach and a nonconvex approach to deal with the square of the time-varying delay appearing in the derivative of the LKF. Through numerical simulation, it is found that: 1) the coupled LKF is more beneficial than the noncoupled LKF for reducing the conservatism of the obtained passivity criteria and 2) the passivity criteria using the convex approach can deliver larger delay upper bounds than those using the nonconvex approach.

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