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1.
J Synchrotron Radiat ; 26(Pt 6): 2024-2032, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31721747

RESUMO

Conventional imaging methods such as magnetic resonance imaging, computed tomography and digital subtraction angiography have limited temporospatial resolutions and shortcomings like invasive angiography, potential allergy to contrast agents, and image deformation, that restrict their application in high-resolution visualization of the structure of microvessels. In this study, through comparing synchrotron radiation (SR) absorption-contrast imaging to absorption phase-contrast imaging, it was found that SR-based phase-contrast imaging could provide more detailed ultra-high-pixel images of microvascular networks than absorption phase-contrast imaging. Simultaneously, SR-based phase-contrast imaging was used to perform high-quality, multi-dimensional and multi-scale imaging of rat brain angioarchitecture. With the aid of image post-processing, high-pixel-size two-dimensional virtual slices can be obtained without sectioning. The distribution of blood supply is in accordance with the results of traditional tissue staining. Three-dimensional anatomical maps of cerebral angioarchitecture can also be acquired. Functional partitions of regions of interest are reproduced in the reconstructed rat cerebral vascular networks. Imaging analysis of the same sample can also be displayed simultaneously in two- and three-dimensional views, which provides abundant anatomical information together with parenchyma and vessels. In conclusion, SR-based phase-contrast imaging holds great promise for visualizing microstructure of microvascular networks in two- and three-dimensional perspectives during the development of neurovascular diseases.

2.
J Ultrasound Med ; 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31737929

RESUMO

OBJECTIVES: The aim of this study was to determine whether any salient differences exist in triple-negative breast cancer (TNBC) between premenopausal and postmenopausal patients by comprehensively comparing the ultrasound (US) and clinicopathologic features of these patients. METHODS: A detailed evaluation of the US and clinicopathologic features of 60 tumors from 60 patients with a diagnosis of TNBC (36 premenopausal and 24 postmenopausal women) was conducted in this retrospective study. RESULTS: Triple-negative breast cancer in premenopausal patients was more likely to show a round or oval shape and microlobulated margins, more commonly exerted effects on surrounding tissue, and showed grade 3 blood flow according to the method of Adler et al (Ultrasound Med Biol 1990; 16:553-559) compared with tumors in postmenopausal women. Triple-negative breast cancer in postmenopausal patients showed some similar US features as those observed in estrogen receptor-positive tumors, including irregular shapes, angular or spiculated margins, and nonparallel growth to the skin (P < .05 for all). CONCLUSIONS: Although US cannot be used to unequivocally identify TNBC, it can distinguish some salient US features regarding TNBC between premenopausal and postmenopausal women. Such information can then provide some valuable predictive information on the diagnosis of TNBC for clinicians.

3.
Artigo em Inglês | MEDLINE | ID: mdl-31738151

RESUMO

INTRODUCTION: p-Cymene (p-CYM) is a common chemical used in air fresheners. OBJECTIVE: The study was designed to investigate the molecular effect of p-CYM on macrophages. MATERIALS AND METHODS: Macrophages (RAW 264.7) were treated with p-CYM (50 uM/L, 150 uM/L and 250 uM/L) for 6 hours, and 24 hours). Gene involved in inflammation such as the Tumor Necrosis Factor-alpha (TNF-α), and the Monocyte Chemoattractant Protein-1 (MCP-1) and other genes known for their antioxidant activity such as the Paraoxonase 1 (PON-1) were analyzed. RESULTS: Cells treated with p-CYM have shown 30% up-regulation of MCP-1 after 24 hour of exposure; and also a differential up-regulation of TNF-α. However, treatment with p-CYM has resulted in a considerable (37%) dose dependent down regulation of PON-1 after 24 hours of exposure. PON-1 is known for its antioxidant properties protecting High-density lipoproteins (HDL) from oxidation. CONCLUSION: Our findings clearly demonstrate that exposure to p-CYM over time promotes oxidative stress by down regulating antioxidants genes as shown in PON-1 and also stimulates inflammation a key process during the initiation and progression of atherosclerosis.

4.
Artigo em Inglês | MEDLINE | ID: mdl-31741390

RESUMO

Charge transfer across the interface and interlayer coupling in graphene van der Waals heterostructure, which is constructed by graphene and semiconducting transition metal dichalcogenides (TMDCs), is critical for their electronic and optoelectronic applications. Photo-induced charge injection from TMDC to graphene has been studied in several heterostructure photodetector. However, the response time significantly varies among different reports, ranging from microseconds to milliseconds. In this work, using graphene/WSe2 heterostructure as an example, we directly observe the carriers density change of graphene by time-resolved optical-pump terahertz (THz)-probe spectroscopy and show ultrafast picosecond photoresponse of graphene. In the absence of photoexcitation, THz time-domain spectroscopic measurements show that WSe2 can transfer holes to graphene and pull down the Fermi level of graphene. After excitation by the ultrafast laser pulse, the transient THz response shows a rapid (∼0.35 ps) increase in the graphene conductivity mainly due to the holes injection from the WSe2 into graphene. Unlike previous reports on band bend as the guidance mechanism for charge transfer, our results show that the relevant mechanism is band offset across the atomically sharp interface.

5.
Molecules ; 24(21)2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31694349

RESUMO

Based upon the intramolecular charge transfer (ICT) mechanism, a novel ratiometric fluorescent probe EB was developed to detect SO32-/HSO3-. The probe displayed both colorimetric and ratiometric responses toward SO32-/HSO3-. It displayed a quick response (within 60 s), good selectivity and high sensitivity (a detection limit of 28 nM) towards SO32-/HSO3-. The SO32-/HSO3- sensing mechanism was confirmed as the Michael addition reaction by ESI-MS. Moreover, the probe could be applied to measure the level of sulfite in real samples, like sugar and chrysanthemum, and it could also be used to detect SO32-/HSO3- in HepG2 cells through confocal fluorescence microscopy, which proved its practical application in clinical diagnosis.

6.
Aging (Albany NY) ; 112019 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-31744937

RESUMO

The aging brain with mitochondrial dysfunction and a reduced adenosine 5'-triphosphate (ATP) has been implicated in the onset and progression of ß-Amyloid (Aß)-induced neuronal toxicity in AD. To unravel the function of ATP and the underlying mechanisms on AD development, APP/PS1 double transgenic mice and wild-type (WT) C57 mice at 6 and 10 months of age were studied. We demonstrated a decreased ATP release in the hippocampus and platelet of APP/PS1 mice, comparing to C57 mice at a relatively early age. Levels of Aß were raised in both hippocampus and platelet of APP/PS1 mice, accompanied by a decrease of α-secretase activity and an increase of ß-secretase activity. Moreover, our results presented an age-dependent rise in mitochondrial vulnerability to oxidation in APP/PS1 mice. In addition, we found decreased pSer473-Akt levels, increased GSK3ß activity by inhibiting phosphorylation at Ser9 in aged APP/PS1 mice and these dysfunctions probably due to down-regulation of Bcl-2 and up-regulation of cleaved caspase-3. Therefore, we demonstrate that PI3K/Akt/GSK3ß signaling pathway could be involved in Aß-associated mitochondrial dysfunction of APP/PS1 mice and APP abnormal metabolism in platelet might provide potential biomarkers for early diagnosis of AD.

7.
Int J Biol Macromol ; 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31760015

RESUMO

Previous work from our research group has isolated and purified an acidic exopolysaccharide (named EPS103) from Lactobacillus plantarum JLAU103, which had strong in vitro antioxidant activity. In this study, we investigated the in vitro immunomodulatory activity of EPS103 in RAW264.7 macrophages with or without lipopolysaccharide (LPS) activation. The results showed that EPS103 enhanced the phagocytic activity of RAW264.7 macrophages and promoted the release of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and nitric oxide (NO) of RAW264.7 macrophages. Moreover, EPS103 reduced the excessive release of IL-6, TNF-α, prostaglandin E2 (PGE2), and NO, as well as inhibited the mRNA expression of IL-6, TNF-α, cyclooxygenase-2 (COX-2), and inducible NO synthase (iNOS) of RAW264.7 macrophages activated by LPS. In mechanistic studies, EPS103 exerted immunomodulatory activity via the nuclear factor-kappa B (NF-κB) signaling pathway. These findings suggest that EPS103 possesses potent dual immunomodulatory activities and could be further developed as new products for functional foods or medicines.

8.
Ecotoxicology ; 28(10): 1220-1231, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31720910

RESUMO

Rice busk biochar was mixed with cobalt (Co)-polluted soil to examine the efficacy of biochar for Co immobilization and detoxification in fluvo-aquic soil. The Co speciation (modified BCR sequential extraction), fluorescein diacetate (FDA) hydrolysis and soil enzyme activities were investigated. In soil, the Co ions (acid-soluble fraction) could be uptake by biochar due to the microporous structure on the surface, as well as the oxygen-containing functional groups and conjugated structure in the molecular structure. Therefore, when the biochar concentration was lower than the optimum concentration (~6 g·kg-1), there was transformation of Co from the acid-soluble fraction to the oxidizable fraction, resulting in lower environmental risk. However, if the biochar concentration continued increasing, the distribution coefficient of Co in the acid-soluble fraction increased (P < 0.05). The biochar could also reduce the toxicity of Co, resulting in the negative correlations between soil enzyme activities (FDA hydrolysis, urease and alkaline phosphatases) and Co in the acid-soluble fraction (r = -0.816, -0.928 and -0.908, respectively, P < 0.01). When the biochar concentration ranged from 5.83 to 6.76 g·kg-1, the efficacy for Co immobilization and detoxification reached the maxima. To conclude, in fluvo-aquic soil, rice busk biochar is an effective amendment for immobilizing Co ions and reducing the toxicity of Co. The biochar concentration in soil should range from 5.83 to 6.76 g·kg-1 to reach the optimum efficacy.

9.
Gene ; : 144147, 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31629822

RESUMO

BACKGROUND: Suicidal ideation (SI) is the most serious symptom of major depressive disorder (MDD) and considered an extreme state. The serotonin transporter gene (SLC6A4) plays a significant role in MDD and suicide pathophysiology. Previous studies have revealed an association between common variants of SLC6A4 with the risk of MDD and suicide. However, very few studies have so far focused on the degree to which rare variants of SLC6A4 are responsible for the depression observed in adolescent and young adult suicide patients. The aim of this study was to examine the impact of common and rare variants of SLC6A4 on the risk of Han Chinese adolescents and young adults suffering MDD with SI. METHODS: Targeted sequencing of the SLC6A4 gene was conducted using FastTarget technology in Han Chinese adolescents and young adults, of which 74 were MDD patients with SI and 150 were healthy controls. Gene-based association analyses of rare variants were performed using enrichment analysis and a cumulative allele test. An allele association study was performed against common variants. RESULTS: After sequencing and bioinformatics analysis, a total of 15 single nucleotide variants (SNVs) were detected in the targeted regions from all participants, including 9 common and 6 rare variants. Among these, 5 rare variants were identified within the study group. Enrichment analysis of rare variants demonstrated a statistical difference (p = 0.042) between the study and control groups. Using cumulative allele analysis, alternative alleles in the SLC6A4 gene exhibited an association with MDD patients with SI (cumulative allele: OR = 10.18, 95% CI = 1.18-87.32, p = 0.017). No significant association was found between the 9 common SLC6A4 variants and MDD patients with SI. CONCLUSIONS: Our results suggest that rare variants of SLC6A4 may contribute to a genetic risk of adolescents and young adults suffering MDD with SI.

10.
Cancer Med ; 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31663690

RESUMO

Adrenergic receptors (ARs) have gained attention for their involvement in breast cancer (BC) progression. Dexmedetomidine, a selective α2 -AR agonist, has been reported to increase the malignancy of BC cells in vitro or stimulate tumor growth in mice. However, clinical evidence is lacking. Clinical research in this area is important as dexmedetomidine is widely used in BC surgery patients. Here we allocated 24 women with primary BC to the dexmedetomidine group (who received a total dose of 2 µg kg-1 dexmedetomidine perioperatively) or to the control group (who received the same volume of normal saline). Venous blood was obtained from all patients immediately upon entering the operating room and 24 hours postoperatively. Serum was then exposed to MCF-7 cells at a concentration of 10% for 24 hours. Cell proliferation, migration, and invasion were analyzed using EdU, Transwell, and Matrigel methods, respectively. We found that postoperative serum from those who received dexmedetomidine was associated with significantly increased cell proliferation, migration, and invasion compared with preoperative serum when used to culture MCF-7 cells. The mean percentage change from post to preoperative values in these cell functions was significantly larger in the dexmedetomidine group than in the control group (proliferation, 30.44% vs 8.45%, P = .0024; migration, 15.90% vs 3.25%, P = .0015; invasion, 8.17% vs 2.13%, P = .04). In conclusion, these findings suggest that in patients undergoing surgery for primary BC, perioperative administration of dexmedetomidine might influence the serum milieu in a way that favors the malignancy of MCF-7 cells. Clinical trial registration: NCT03108937.

11.
Artigo em Inglês | MEDLINE | ID: mdl-31642163

RESUMO

Checkpoint blockade immunotherapy (CBI) awakes host innate immune system and reactivates cytotoxic T cells to elicit durable response in some cancer patients. Herein we report the use of a cationic nanoscale metal-organic framework, W-TBP, to facilitate tumor antigen presentation by enabling immunogenic photodynamic therapy (PDT) and promoting the maturation of dendritic cells (DCs). Comprised of dinuclear W VI secondary building units and photosensitizing 5,10,15,20-tetra( p -benzoato)porphyrin (TBP) ligands, cationic W-TBP mediates PDT to release tumor associated antigens and delivers immunostimulatory CpG oligodeoxynucleotides to DCs. The enhanced antigen presentation synergizes with CBI to expand and reinvigorate cytotoxic T cells, leading to superb anticancer efficacy and robust abscopal effects with >97% tumor regression in a bilateral breast cancer model.

12.
Hepatology ; 2019 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-31610032

RESUMO

Yes-associated protein (YAP) plays an important role in hepatocarcinogenesis, although the potential role of YAP in non-neoplastic liver diseases remains largely unknown. We report herein that YAP in Kupffer cells (KCs) enhances the production of pro-inflammatory cytokines and promotes the development of non-alcoholic steatohepatitis. Our data show that the expression of YAP is significantly increased in KCs of wild type mice fed HFD. We then generated mice with macrophage/monocyte-specific deletion of YAP (YAPϕKO ) or TLR4 (TLR4ϕKO ) and the animals were fed high fat diet (HFD) or treated with LPS. Our data showed that YAPϕKO mice fed HFD exhibited lower serum ALT/AST levels and less hepatic inflammation when compared to their littermate controls. LPS treatment induced the accumulation of YAP in KCs in vitro and in mice which was prevented by macrophage/monocyte-specific deletion of TLR4 (TLR4ϕKO ). LPS transcriptionally activates YAP via AP-1 in macrophages/KCs. The LPS-induced YAP further enhances the expression of pro-inflammatory cytokines (including MCP-1, TNF-α and IL-6) through YAP association with the TEAD-binding motif in the promoter region of inflammatory cytokines. Forced overexpression of active YAP (YAP5SA) in KCs enhanced the production of pro-inflammatory cytokines. Treatment of HFD-fed mice with verteporfin inhibited Kupffer cell activation, reduced liver inflammation and decreased serum ALT/AST levels. Analyses of liver tissues from NASH patients reveal that YAP is increased in KCs and that the level of YAP in human liver tissues is positively correlated with the expression of pro-inflammatory cytokines. Conclusions: This study describes an important role of YAP in Kupffer cells for regulation of liver inflammation in NASH. Our findings suggest that inhibition of YAP may represent a novel and effective therapeutic strategy for NASH treatment.

13.
Neuroimage ; 205: 116278, 2019 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-31614221

RESUMO

Preclinical applications of resting-state functional magnetic resonance imaging (rsfMRI) offer the possibility to non-invasively probe whole-brain network dynamics and to investigate the determinants of altered network signatures observed in human studies. Mouse rsfMRI has been increasingly adopted by numerous laboratories worldwide. Here we describe a multi-centre comparison of 17 mouse rsfMRI datasets via a common image processing and analysis pipeline. Despite prominent cross-laboratory differences in equipment and imaging procedures, we report the reproducible identification of several large-scale resting-state networks (RSN), including a mouse default-mode network, in the majority of datasets. A combination of factors was associated with enhanced reproducibility in functional connectivity parameter estimation, including animal handling procedures and equipment performance. RSN spatial specificity was enhanced in datasets acquired at higher field strength, with cryoprobes, in ventilated animals, and under medetomidine-isoflurane combination sedation. Our work describes a set of representative RSNs in the mouse brain and highlights key experimental parameters that can critically guide the design and analysis of future rodent rsfMRI investigations.

14.
J Biosci Bioeng ; 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31630942

RESUMO

Hazelnut proteins are an excellent source of bioactive peptides. Our previous study demonstrated that several novel peptides derived from Corylus heterophylla Fisch (C. heterophylla Fisch) have antioxidant and anti-inflammatory activities. In this study, we purified and identified anti-obesity peptides from hazelnut protein hydrolysates by chromatography and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Subsequently, we evaluated the inhibitory effect of the synthetic peptide on adipogenesis in 3T3-L1 adipocytes by Oil Red O staining, reverse transcription polymerase chain reaction (RT-PCR) and western blot. The results showed that a novel synthetic pentapeptide, Arg-Leu-Leu-Pro-His (RLLPH), derived from the C3 fraction, attenuated adipogenesis by downregulating the expression of several mRNAs related to adipogenesis, including peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer binding protein alpha (C/EBPα), adipocyte fatty acid-binding protein 2 (aP2), sterol regulatory element binding protein 1c (SREBP-1c), fatty acid synthase (FAS), acetyl-CoA carboxylase 1 (ACC1), and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR). Moreover, RLLPH upregulated the levels of phosphorylated Adenosine monophosphate-activated protein kinase (AMPK) and its substrate acetyl-CoA carboxylase (ACC) in 3T3-L1 adipocytes. A stability study revealed that RLLPH was relatively stable during pepsin digestion. These findings suggest that RLLPH has potential anti-obesity effects and may help combat metabolic diseases.

15.
Int J Mol Sci ; 20(18)2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31510092

RESUMO

There is accumulating evidence supporting electroacupuncture's (EA) therapeutic effects. In mice, local EA reliably attenuates inflammatory pain and increases the transient receptor potential cation channel, subfamily V, member 1 (TRPV1). However, the effect of distal acupoint EA on pain control has rarely been studied. We used a mouse model to investigate the analgesic effect of distal EA by measuring TRPV1 expression in the brain. Complete Freund's adjuvant (CFA) was injected into mice's hind paws to induce inflammatory pain. The EA-treated group received EA at the LI4 acupoint on the bilateral forefeet on the second and the third days, whereas the control group underwent sham manipulation. Mechanical and thermal pain behavior tests showed that the EA-treated group experienced inflammatory pain alleviation immediately after EA, which did not occur in the sham group. Additionally, following CFA injection, the expression of TRPV1-associated molecules such as phosphorylated protein kinase A (pPKA), extracelluar signal-regulated kinase (pERK), and cAMP-response-element-binding protein (pCREB) increased in the prefrontal cortex (PFC) and the hypothalamus but decreased in the periaqueductal gray (PAG) area. These changes were significantly attenuated by EA but not sham EA. Our results show an analgesic effect of distal EA, which is based on the traditional Chinese medicine theory. The mechanism underlying this analgesic effect involves TRPV1 in the PFC, the hypothalamus, and the PAG. These novel findings are relevant for the evaluation and the treatment of clinical inflammatory pain syndrome.

16.
Anal Chem ; 91(21): 13947-13952, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31558029

RESUMO

Gold nanoclusters (Au NCs) coated with various peptides have been widely used as fluorescent probes, and nowadays the most commonly used are cysteine (C) and tyrosine (Y) based ones. Herein, we report the preparation and clinical application of highly efficient and stable fluorescent Au NCs protected by screened peptides with a specific amino acid sequence Cys-Met-Met-Met-Met-Met (CMMMMM). Compared with traditional C, Y based peptide (CYYYYY) protected Au NCs, the fluorescence intensity of the CMMMMM-Au NCs increased by 230%, and the photobleaching resistance or stability of the CMMMMM-Au NCs increased by about 300% (after continuous ultraviolet irradiation for 60 min, the fluorescence of the CMMMMM-Au NCs remained more than 90% of their initial intensity, while the CYYYYY-Au NCs remained less than 30%). Assaying arrays based on CMMMMM protected Au NCs with different positive or negative charges as sensing receptors were developed through regulating different pH values, and multivariate analysis on the patterns obtained by these arrays allowed effective identification of not only ten proteins separately but also complex protein mixtures with subtly diverse compositions. The docking simulation and isothermal titration confirmed that target proteins interacted with CMMMMM-Au NCs mainly through electrostatic interactions and partly hydrophobic interactions, which affected the binding energy and fluorescence lifetime of CMMMMM-Au NCs, resulting in the unique fingerprint-like recognition patterns. Furthermore, serums from breast cancer, severe osteoarthritis, and rectal cancer patients can be effectively identified with healthy people using this CMMMMM-Au NCs based sensor array.

17.
J Sep Sci ; 42(22): 3421-3431, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31529668

RESUMO

A simple and efficient method based on ultrafiltration with liquid chromatography and mass spectrometry was used for the rapid screening and identification of ligands in the extracts of Stellera chamaejasme. The bound ligands, i.e. daphnoretin, isopimpinellin, chamaechromone, neochamaejasmin A, and chamaejasmine (purity of 96.8, 90.75, 91.41, 93.98, and 98.91%, respectively), were separated by semi-preparative high-performance liquid chromatography combined with high-speed counter-current chromatography. To the best of our knowledge, this is the first study to report the detection of potent lipoxidase and lactate dehydrogenase inhibitors in Stellera chamaejasme extracts. The results demonstrate that our method of ultrafiltration with liquid chromatography and mass spectrometry combined with mixed chromatography can be used to screen and confirm the bioactivity of all isolated compounds. This method also eliminates the need for separation of inactive compounds, thereby improving efficiency when studying bioactive substances. For some complex mixtures, neither semi-preparative high-performance liquid chromatography nor high-speed counter-current chromatography can purify all the target active compounds with high purity in a one-step separation. The combination of the two methods allow for efficient purification of target bioactive compounds with different polarities and physicochemical properties based on their complementary properties.

18.
Obes Rev ; 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31482658

RESUMO

Childhood obesity is one of the most pressing public health issues nowadays. The environmental factors have been identified as potential risks for obesity, as they may influence people's lifestyle behaviours. Lack of access to supermarkets that usually provide healthy food options has been found to be a risk factor for childhood obesity in several studies. However, findings remained inconclusive. We aimed to systematically review the association between access to supermarkets and childhood obesity. A literature search was conducted in the Cochrane Library, PubMed, Web of Science, and Embase for studies published before 1 January 2019. Twenty-four studies conducted in four countries were identified, from which data on the basic characteristics of studies and participants, measures of access to supermarkets, and associations between access to supermarkets and weight-related behaviours and outcomes were extracted. The median sample size was 1858 participants. Half of the included studies indicated a negative association, one fourth reported a positive association, and the remaining one fourth did not find a significant association. Better designed studies are necessary to achieve a robust understanding of this epidemiological relationship in the future.

19.
Nanotechnology ; 30(46): 465703, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31476137

RESUMO

The Fe3O4@Au core-shell nanocomposites, as the multifunctional magnetic surface enhanced Raman scattering (SERS) substrates, were fabricated successfully by the seeds growth method based on the Fe3O4-Au core-satellite nanocomposites. The SERS properties of the Fe3O4-Au core-satellite nanocomposites and the Fe3O4@Au core-shell nanocomposites were compared using 4-aminothiophenol (4-ATP) as the probe molecule. It was found that Fe3O4@Au core-shell nanocomposites showed better SERS performance than Fe3O4-Au core-satellite nanocomposites. The Au shell provided an effectively large surface area for forming sufficient plasmonic hot spots and capturing target molecules. The integration of magnetic core and plasmonic Au nanocrystals endowed the Fe3O4@Au core-shell nanocomposites with highly efficient magnetic separation and enrichment ability and abundant interparticle hot spots. The Fe3O4@Au core-shell nanocomposites could be easily recycled because of the intrinsic magnetism of the Fe3O4 cores and had good reproducibility of the SERS signals. For practical application, the Fe3O4@Au core-shell nanocomposites were also used to detect thiram. There was a good linear relationship between the SERS signal intensity and the concentration of thiram from 1 × 10-3 to 1 × 10-8 M and the limit of detection was 7.69 × 10-9 M. Moreover, residual thiram on apple peel was extracted and detected with a recovery rate range of 99.3%. The resulting substrate with high SERS activity, stability and strong magnetic responsivity makes the Fe3O4@Au core-shell nanocomposites a perfect choice for practical SERS detection applications.

20.
Opt Express ; 27(18): 26050-26059, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31510465

RESUMO

Optical image encryption technique has become extremely important in these years. However, most of the proposed multiple-image encryption systems are illuminated with coherent light source. Here we present a multiple-image double-encryption method with spatially incoherent illumination. The first-encryption of multiple images is based on the speckle rotation decorrelation property, and the second-encryption of images' order is based on the speckle shift decorrelation out of the angular memory-effect range. The double-encryption via two-dimensional rotations of the random phase mask enhances the security and keeps the simplicity of the cryptosystem. The capacity of the ciphertext is greatly increased by multiplexing, and further increased after crosstalk noise removal. The use of incoherent light source reduces the requirements for experimental conditions, and makes the cryptosystem easy to implement in various application scenarios.

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