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1.
J Pharm Biomed Anal ; 207: 114400, 2022 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-34624818

RESUMO

A sensitive and ratiometric electrochemical biosensor was developed for the determination of dimethoate via alkaline phosphatase (ALP) mediated dissolution of nano-MnO2 and [Ru(NH3)6]3+(Ru(III)) redox recycling. The electroactive probe Ru(III) was adsorbed on the nano-MnO2 with the high specific surface area through electrostatic interaction to form the MnO2-Ru(III) nanocomposite, which was then fixed on the surface of the glassy carbon electrode. When the dimethoate inhibited the catalytic activity of ALP in a homogeneous system, the hydrolysate L-ascorbic acid (AA) produced by ALP hydrolysis of L-ascorbic acid-trisodium 2-phosphate (AAP) decreased. The solution was then incubated with a glassy carbon electrode modified by MnO2-Ru(III). At this time, only a small amount of MnO2-Ru(III) was decomposed and Ru(III) was rapidly electroreduced to Ru(II) on the surface of the electrode. The in-situ produced Ru(II) was chemically oxidized back to Ru(III) by Fe(III). The redox recycling of Ru(III) was completed and the Ru(III) reduction current signal was amplified. The process consumed part of Fe(III) to reduce the reduction current signal of Fe(III), and the ratio of the two reduction currents (IRu(III)/IFe(III)) increased significantly. The IRu(III)/IFe(III) value increased with the increase of dimethoate concentration in the linear range of 0.01-300 ng mL-1, and the detection limit was 6.3 pg mL-1. It has been successfully applied to the determination of dimethoate in oilseed rape and lettuce with a satisfactory result.


Assuntos
Fosfatase Alcalina , Técnicas Biossensoriais , Dimetoato , Compostos Férricos , Compostos de Manganês , Oxirredução , Óxidos , Solubilidade
2.
Adv Healthc Mater ; : e2102073, 2021 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-34731532

RESUMO

The accurate diagnosis and targeted therapy of malignant tumors face significant challenges. To address these, an oxidized molybdenum polyoxometalate-copper nanocomposite (Ox-POM@Cu) is designed and synthesized here. The doping with Cu determines the formation of oxygen vacancies, which can increase the carrier concentration in Ox-POM@Cu, accelerate electron transfer, and enhance the redox activity, thus playing an efficient catalytic role. The nanocomposite presents unique enzymatic functions characterized by a multielement catalytic activity in the tumor microenvironment (TME). In addition, it can be employed as an NIR-II photoacoustic imaging (PAI) probe and cancer therapy agent. First, it participates in a redox reaction with glutathione (GSH) in tumor tissues, activates the PAI and photothermal therapy functions via NIR-II irradiation, and depletes the GSH supply in cancerous cells. Subsequently, it catalyzes a Fenton-like reaction with H2 O2 in tumor tissues to form hydroxyl radicals, thereby performing a chemodynamic therapy function. The findings show that the developed nanoenzyme is very efficient in the diagnosis and treatment of malignant tumors. This work not only provides a new strategy for the design of TME-induced NIR-II PAI but also presents new insights into enhanced cancer therapy.

3.
Analyst ; 2021 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-34787607

RESUMO

The multicolor-based point-of-care testing (POCT) of tumor cell-derived exosomes is of vital importance for understanding tumor growth and metastasis. Multicolor-based ratiometric signals most often rely on molecular optics, such as fluorescence resonance energy transfer (FRET)-dependent molecular fluorescence and localized surface plasmon resonance (LSPR)-related molecular colorimetry. However, finding acceptable FRET donor-acceptor fluorophore pairs and the kinetically slow color responses during size-related molecular colorimetry have greatly impeded POCT applications. Herein, an atomic flame was used to develop a visual sensing platform for the POCT of tumor-cell-derived exosomes. In comparison with common molecular optics, the atomic flame possessed the advantages of providing both a variety of ratiometric flame signals and fast response sensitivity. The integration of a gas-pressure-assisted flame reaction and dual-aptamer recognition guaranteed the sensitive and selective analysis of exosomes with a low limit of detection (LOD) of 7.6 × 102 particles per mL. Such a novel optical signal will inspire the development of more user-friendly POCT approaches.

4.
Chem Commun (Camb) ; 57(84): 11017-11020, 2021 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-34605511

RESUMO

A DNAzyme-mediated target-initiated rolling circle signal amplification strategy based on a microchip platform was developed for detecting apurinic/apyrimidine endonuclease 1 (APE1) at the single-cell level. This strategy was applied to assays of lysate samples from HL-7702, HeLa and MCF-7 cells, with a detection limit of lower than 1 HeLa cell.

5.
Chem Commun (Camb) ; 57(88): 11617-11620, 2021 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-34643633

RESUMO

Since the photothermal heating of plasmonic spherical nucleic acids (pSNAs) depends on the self-assembly level and melting temperature (Tm), a temperature-self-controllable and biomarker-activatable photothermal effect in vivo was thus achieved using the Tm-dependent assembly-disassembly of pSNAs.

6.
Clin Cancer Res ; 27(23): 6491-6499, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34518308

RESUMO

PURPOSE: Our team previously defined six quantitative transcriptomic components, and a classification in five subtypes by association of these components. In this study, we compared the robustness of quantitative components and qualitative classifications from different transcriptomic profiling techniques, investigated their clinical relevance, and proposed a new prognostic model. EXPERIMENTAL DESIGN: A total of 210 patients from a multicentric cohort and 149 patients from a monocentric cohort were included in this study. RNA microarray profiles were obtained from 165 patients of the multicentric cohort. RNA sequencing (RNA-seq) profiles were obtained from all the patients. RESULTS: For the patients with both RNA microarray and RNA-seq profiles, the concordance in subtype assignment was partial with an 82.4% coherence rate. The correlation between the two technique projections of the six components ranged from 0.85 to 0.95, demonstrating an advantage of robustness. On the basis of the Akaike information criterion, the RNA components showed more prognostic value in univariate or multivariate models than the subtypes. Using the monocentric cohort for training, we developed a multivariate Cox regression model using all six components and clinicopathologic characteristics (node invasion and resection margins) on disease-free survival (DFS). This prognostic model was highly associated with DFS (P < 0.001). The evaluation of the model in the multicentric cohort showed significant association with DFS and overall survival (P < 0.001). CONCLUSIONS: We described the advantage of the prognostic value and robustness of the whole-tumor transcriptomic components than subtypes. We created and validated a new DFS-based multivariate Cox regression prognostic model, including six pancreatic adenocarcinoma transcriptomic component levels and pathologic characteristics.

7.
Anal Chim Acta ; 1181: 338926, 2021 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-34556211

RESUMO

A multicolor and photothermal dual-mode assay for sensitive alkaline phosphatase (ALP) determination was realized based on the 3,3',5,5'-tetramethylbenzidine (TMB)-induced etching of gold nanorods (AuNRs). TMB was oxidized under ultraviolet light irradiation to form TMB+. In the presence of ALP, ascorbic acid phosphate (AAP) is converted to ascorbic acid, which can then reduce the levels of TMB+, resulting in lower concentrations of TMB+. The remaining TMB+ was transformed into TMB2+ after the addition of HCl solution. AuNRs were etched by TMB2+ to produce a multicolor and photothermal change. Based on the degree of AuNRs etching, this highly sensitive dual-mode assay provided a linear range of 1.0-8.0 mU/mL, with detection limits of 0.34 mU/mL for the multicolor assay and 0.11 mU/mL for the photothermal assay. This method was successfully applied to the determination of ALP in serum samples.


Assuntos
Ouro , Nanotubos , Fosfatase Alcalina , Colorimetria , Raios Ultravioleta
8.
Analyst ; 146(18): 5643-5649, 2021 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-34378556

RESUMO

Highly specific and ultrasensitive detection of uracil-DNA glycosylase (UDG) activity is of great significance for maintaining genomic integrity and medical research of related diseases. Here, we constructed a random DNA walking nanomachine based on a DNAzyme for UDG activity detection on the AuNP (Au nanoparticle) surface. When UDG is present, the U bases in the Y structure are removed, resulting in AP sites, which will be cleaved by Endo-IV to generate a 3' concave end for Exo-III, causing the locking strand of the DNAzyme to be completely hydrolyzed by the Exo-III and release the walking strand to randomly pair with the substrate strand on the AuNP surface; then, the walking strand exerts its cleavage activity with the assistance of Mg2+ to cleave the substrate strand and keep the fluorophore 6-carboxyfluorescein (FAM) away from the surface of the AuNP, which restores the fluorescence signal of this system. In this way, sensitive detection of UDG can be realized, and the detection limit is as low as 3.69 × 10-6 U mL-1. In addition, we found that this method is highly specific to UDG and can be used to detect UDG specifically in complex samples, which has certain application prospects in biomedical research and clinical diagnosis related to UDG.


Assuntos
DNA Catalítico , Nanopartículas Metálicas , DNA , Ouro , Limite de Detecção , Uracila-DNA Glicosidase
9.
Small ; 17(37): e2102293, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34342137

RESUMO

Electrochemical CO2 reduction reaction (CO2 RR) is critical to converting CO2 to high-value multicarbon chemicals. However, the Cu-based catalysts as the only option to reduce CO2 into C2+ products suffer from poor selectivity and low activity. Tandem catalysis for CO2 reduction is an efficient strategy to overcome such problems. Here, Cu@Ag core-shell nanoparticles (NPs) with different silver layer thicknesses are fabricated to realize the tandem catalysis for CO2 conversion by producing CO on Ag shell and further achieving C-C coupling on Cu core. It is found that Cu@Ag-2 NPs with the proper thickness of Ag shell exhibit the Faradaic efficiency (FE) of total C2 products and ethylene as high as 67.6% and 32.2% at -1.1 V (versus reversible hydrogen electrode, RHE), respectively. Moreover, it exhibits remarkably electrocatalytic stability after 14 h. Based on electrochemical tests and CO adsorption capacity analyses, the origin of the enhanced catalytic performance can be attributed to the synergistic effect between Ag shell and Cu core, which strengthens the bonding strength of CO on Cu/Ag interfaces, expedites the charge transfer, increases the electrochemical surface areas (ECSAs). This report provides a Cu-based catalyst to realize efficient C2 generation via a rationally designed core-shell structured catalyst.

10.
Front Immunol ; 12: 653711, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34354698

RESUMO

Background: Glioblastoma (GBM), one of the most aggressive tumors of the brain, has no effective or sufficient therapies. Identifying robust biomarkers for the response to immune checkpoint blockade (ICB) therapy, a promising treatment option for GBM patients, is urgently needed. Methods: We comprehensively evaluated lncRNA m6A modification patterns in m6A-sequencing (m6A-seq) data for GBM tissues and systematically investigated the immune and stromal regulators of these m6A-regulated lncRNAs. We used the single-sample gene-set enrichment analysis (ssGSEA) algorithm to investigate the difference in enriched tumor microenvironment (TME) infiltrating cells and the functional annotation of HSPA7 in individual GBM samples. Further, we validated that HSPA7 promoted the recruitment of macrophages into GBM TME in vitro, as well as in our GBM tissue section. We also explored its impact on the efficacy of ICB therapy using the patient-derived glioblastoma organoid (GBO) model. Results: Here, we depicted the first transcriptome-wide m6A methylation profile of lncRNAs in GBM, revealing highly distinct lncRNA m6A modification patterns compared to those in normal brain tissues. We identified the m6A-modified pseudogene HSPA7 as a novel prognostic risk factor in GBM patients, with crucial roles in immunophenotype determination, stromal activation, and carcinogenic pathway activation. We confirmed that HSPA7 promoted macrophage infiltration and SPP1 expression via upregulating the YAP1 and LOX expression of glioblastoma stem cells (GSCs) in vitro and in our clinical GBM tumor samples. We also confirmed that knockdown of HSPA7 might increase the efficiency of anti-PD1 therapy utilizing the GBO model, highlighting its potential as a novel target for immunotherapy. Conclusions: Our results indicated that HSPA7 could be a novel immunotherapy target for GBM patients.


Assuntos
Neoplasias Encefálicas/tratamento farmacológico , Resistencia a Medicamentos Antineoplásicos/genética , Glioblastoma/tratamento farmacológico , Proteínas de Choque Térmico HSP70/metabolismo , Inibidores de Checkpoint Imunológico/farmacologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Adenosina/análogos & derivados , Adenosina/metabolismo , Encéfalo/patologia , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/imunologia , Neoplasias Encefálicas/mortalidade , Linhagem Celular Tumoral , Conjuntos de Dados como Assunto , Regulação Neoplásica da Expressão Gênica/imunologia , Técnicas de Silenciamento de Genes , Glioblastoma/genética , Glioblastoma/imunologia , Glioblastoma/mortalidade , Proteínas de Choque Térmico HSP70/genética , Humanos , Inibidores de Checkpoint Imunológico/uso terapêutico , Estimativa de Kaplan-Meier , Osteopontina/genética , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Receptor de Morte Celular Programada 1/metabolismo , Proteína-Lisina 6-Oxidase/genética , RNA-Seq , Fatores de Transcrição/genética , Resultado do Tratamento , Microambiente Tumoral/genética , Microambiente Tumoral/imunologia , Macrófagos Associados a Tumor/imunologia , Macrófagos Associados a Tumor/metabolismo
11.
ACS Appl Mater Interfaces ; 13(30): 35365-35375, 2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34286953

RESUMO

Phototherapy exhibits significant potential as a novel tumor treatment method, and the development of highly active photosensitizers and photothermal agents has drawn considerable attention. In this work, S and N atom co-doped carbon dots (S,N-CDs) with an absorption redshift effect were prepared by hydrothermal synthesis with lysine, o-phenylenediamine, and sulfuric acid as raw materials. The near-infrared (NIR) absorption features of the S,N-CDs resulted in two-photon (TP) emission, which has been used in TP fluorescence imaging of lysosomes and tumor tissue pH and real-time monitoring of apoptosis during tumor phototherapy, respectively. The obtained heteroatom co-doped CDs can be used not only as an NIR imaging probe but also as an effective photodynamic therapy/photothermal therapy (PDT/PTT) therapeutic agent. The efficiencies of different heteroatom-doped CDs in tumor treatment were compared. It was found that the S,N-CDs showed higher therapeutic efficiency than N-doped CDs, the efficiency of producing 1O2 was 27%, and the photothermal conversion efficiency reached 34.4%. The study provides new insight into the synthesis of carbon-based nanodrugs for synergistic phototherapy and accurate diagnosis of tumors.


Assuntos
Antineoplásicos/uso terapêutico , Corantes Fluorescentes/uso terapêutico , Neoplasias/diagnóstico por imagem , Neoplasias/tratamento farmacológico , Fármacos Fotossensibilizantes/uso terapêutico , Pontos Quânticos/uso terapêutico , Animais , Antineoplásicos/química , Antineoplásicos/efeitos da radiação , Apoptose/efeitos dos fármacos , Carbono/química , Carbono/efeitos da radiação , Corantes Fluorescentes/química , Corantes Fluorescentes/efeitos da radiação , Fluorometria , Células HeLa , Humanos , Concentração de Íons de Hidrogênio , Lisossomos/metabolismo , Camundongos Nus , Neoplasias/metabolismo , Nitrogênio/química , Nitrogênio/efeitos da radiação , Fótons , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/efeitos da radiação , Fototerapia , Pontos Quânticos/química , Pontos Quânticos/efeitos da radiação , Oxigênio Singlete/metabolismo , Enxofre/química , Enxofre/efeitos da radiação
12.
Mol Ther ; 29(12): 3449-3464, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34217892

RESUMO

Glioma is a heterogeneous cellular environment in which immune cells play critical roles in tumor progression. Myeloid-derived suppressor cells (MDSCs) contribute to the formation of the immunosuppressive microenvironment of glioma; however, how glioma cells interact with MDSCs and how this interaction affects the function of other immune cells are unclear. Glioma cells can systemically communicate with immune cells via the secretion of exosomes, which contain microRNAs (miRNAs). Leveraging miRNA sequencing of exosomes, we identified enrichment of miR-1246 in glioma-derived exosomes and exosomes isolated from the cerebrospinal fluid (CSF) of glioma patients. We demonstrated that miR-1246 drives the differentiation and activation of MDSCs in a dual specificity phosphatase 3 (DUSP3)/extracellular signal­regulated kinase (ERK)-dependent manner. In addition, postoperative CSF exosomal miR-1246 expression was found to be associated with the glioma recurrence rate. Hypoxia, a well-recognized feature of the glioblastoma microenvironment, increased miR-1246 levels in glioma-derived exosomes by enhancing miR-1246 transcription and selective packaging via upregulation of POU class 5 homeobox 1 (POU5F1) and heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1). Importantly, we identified a mechanism of 2-methoxyestradiol, a microtubule inhibitor currently undergoing clinical trials for glioblastoma. 2-Methoxyestradiol suppresses MDSC activation by inhibiting hypoxia-driven exosomal miR-1246 expression in glioma cells and PD-L1 expression in MDSCs.

13.
Biosensors (Basel) ; 11(7)2021 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-34201518

RESUMO

Metal-organic framework (MOF) nanozymes, as emerging members of the nanozymes, have received more and more attention due to their composition and structural characteristics. In this work, we report that mixed-valence state Ce-MOF (MVCM) has intrinsic haloperoxidase-mimicking activity. MVCM was synthesized by partial oxidation method using Ce-MOF as a precursor. In the presence of H2O2 and Br-, MVCM can catalyze oxidative bromination of chromogenic substrate phenol red (PR) to produce the blue product bromophenol blue (Br4PR), showing good haloperoxidase-like activity. Because of the special chromogenic substrate, we constructed a ratiometric colorimetric-sensing platform by detecting the absorbance of the MVCM-(PR, Br-) system at wavelengths of 590 and 430, for quantifying H2O2, where the detection limit of the H2O2 is 3.25 µM. In addition, the haloperoxidase-mimicking mechanism of the MVCM is proposed. Moreover, through enzyme kinetics monitoring, the Km (H2O2 and NH4Br) of the MVCM is lower than that of cerium oxide nanomaterials, indicating that the MVCM has a stronger binding affinity for H2O2 and NH4Br than other materials. This work provides more application prospects for the development of nanozymes in the field of biosensors in the future.


Assuntos
Colorimetria , Peróxido de Hidrogênio/análise , Materiais Biomiméticos , Técnicas Biossensoriais , Catálise , Cério , Limite de Detecção , Estruturas Metalorgânicas , Oxirredução
14.
Chem Sci ; 12(13): 4883-4888, 2021 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-34163738

RESUMO

Photoacoustic (PA) imaging with both the high contrast of optical imaging and the high spatial resolution of ultrasound imaging has been regarded as a robust biomedical imaging technique. Autoimmune hepatitis (AIH) is the second largest liver inflammatory disease after viral hepatitis, but its pathogenesis is not fully understood probably due to the lack of an effective in vivo monitoring approach. In this work, an innovative selenol-activated ratiometric PA imaging probe APSel was developed for visual monitoring of pathological progress of AIH. Selenols including selenocysteine (Sec, the major form of Se-containing species in vivo) have been demonstrated to have an effective antioxidant role in inflammation. The reaction of APSel with selenol results in a blue shift of the PA spectrum peak from 860 nm to 690 nm, which enables the ratiometric PA imaging. The APSel probe displays high sensitivity and selectivity to Sec and other selenols. The APSel probe was then employed for ratiometric PA imaging of selenol in cells, and for monitoring the development of AIH in a murine model by tracking the changes of selenol level. The results revealed that the level of selenol was closely correlated with the development of AIH. The proposed APSel, as the first example of a selenol-responsive PA imaging probe, provides a new tool and approach to study and diagnose AIH diseases.

15.
Chemosphere ; 283: 131167, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34153915

RESUMO

Compared with the Z-scheme and type-II heterojunctions, p-n type heterojunctions are more favorable for the migration of photo-induced carriers owing to the advantage of built-in electric fields. In addition, it is still of great significance to understand the carrier migration properties of the p-n heterojunction. Therefore, the development of new p-n heterojunctions and the development of high-efficiency catalysts with effective modulation of light responsiveness and rapid transfer of charge to achieve photocatalytic inactivation have attracted much attention. In this study, we synthesized a Ag2S/g-C3N4 heterojunction via the in situ deposition of Ag2S onto the g-C3N4 substrate. The prepared Ag2S/g-C3N4 composite facilitated photo-generated charge carrier transfer and exhibited outstanding photocatalytic inactivation of bacteria compared to that of a single catalyst under visible light irradiation. In addition, the ACN-2 composites fully deactivated 7 log10 CFU/mL E. coli and 7 log10 CFU/mL S. aureus cells in 90 min under visible light. The quenching experiments confirmed that photo-generated active species (O2-, OH, and h+) were the major reactive oxygen species that contributed to the inactivation of bacteria. Energy band alignment analysis indicated that a type-II band alignment was formed in the p-n heterostructure, thereby providing strong support for the photocatalytic mechanism. This study not only provides insights into the design of p-n heterostructures, but also presents a promising strategy to enhance the photocatalytic capacities of g-C3N4 based materials for pathogen inactivation.


Assuntos
Desinfecção , Escherichia coli , Grafite , Luz , Compostos de Nitrogênio , Compostos de Prata , Staphylococcus aureus
16.
Anal Chem ; 93(26): 9218-9225, 2021 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-34128642

RESUMO

The absolute quantification of miRNAs in a single cell allows to better understand the heterogeneity of cells and the relationship between miRNAs and diseases. However, seldom methods for miRNA quantification in a single cell have been reported because the miRNA content in a single cell is very low. Herein, an ultrasensitive chemiluminescence assay strategy based on rolling circle amplification (RCA) on a microchip platform was proposed for the absolute quantification of miRNAs in a single cell. In this strategy, a ring probe with specificity was designed and synthesized, which could perform RCA for target miRNAs to improve the sensitivity and satisfy the need of absolute quantification of miRNAs in a single cell. The 20 liver cancer cells (HepG2) and 20 normal liver cells (HL-7702) were analyzed using this method; it is found that the miRNA-21 contents varied among cells, and miRNA-21 was overexpressed in HepG2 cells. Compared with traditional methods, the proposed strategy has many advantages such as low cost, simple operation, short analysis time, good specificity, and lower probability of false positives. This method is expected to be one of the powerful tools for the absolute quantification of miRNAs in a single cell.


Assuntos
MicroRNAs , Células Hep G2 , Humanos , Limite de Detecção , Luminescência , MicroRNAs/genética , Técnicas de Amplificação de Ácido Nucleico , Análise de Célula Única
17.
J Colloid Interface Sci ; 603: 172-181, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34186396

RESUMO

Design and construction of a matrix with specific adsorption on the target compounds can effectively reduce the detection limit of surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS) analysis. Sulfonic acid functionalized hierarchical porous covalent organic frameworks (H-COF-SO3H) was synthesized by defect-structure and post-modification method, and then used as matrix and adsorbent for the determination of quaternary ammonium herbicides paraquat (PQ) and diquat (DQ). N2 adsorption-desorption experiments confirmed that H-COF-SO3H possesses hierarchical porosity with pore widths concentrated at 1.3,1.5, and 2.8 nm. The strong UV absorption at 200-450 nm and good thermal stability made H-COF-SO3H being a promising matrix without background interference. H-COF-SO3H can efficiently enrich PQ and DQ via electrostatic attraction, and the key role of -SO3H group on specific adsorption was confirmed by density functional theory (DFT) calculations. The limits of detection (LODs) for PQ and DQ with H-COF-SO3H enrichment were 0.5 and 0.1 ng·mL-1, respectively, which were 20 and 60 times higher than those without H-COF-SO3H enrichment, respectively. The spiked recoveries of PQ and DQ for the three food samples were 92.0-113.2% and 80.1-102.6% with RSDs of 2.2-9.2% and 2.0-8.7%, respectively. This work provides an analyte-oriented approach for fabricating SALDI-TOF MS matrix.


Assuntos
Diquat , Estruturas Metalorgânicas , Paraquat , Porosidade , Ácidos Sulfônicos
18.
Talanta ; 231: 122421, 2021 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-33965010

RESUMO

Peroxynitrite (ONOO-) is a series of basic biological oxidants involved in physiological and pathological processes. The detection of ONOO- in biological systems has been challenging due to its extremely short half-life and low steady-state concentration. In this work, a ratiometric fluorescent nanoprobe for ONOO- was constructed by coupling covalently of graphene quantum dots (GQDs) with cyanine 5.5 (Cy5.5). This nanoprobe (GQD-Cy5.5) could selectively accumulate in mitochondrial, appears two strong fluorescence emission peaks at 520 and 694 nm. In the presence of ONOO-, the intensity of fluorescence emission peak at 520 nm increased and the intensity of fluorescence emission peak at 694 nm decreased. The ratio (F520 nm/F694 nm) of fluorescence intensity at two emission peaks had a good linear relationship with the concentration of ONOO- in the range of 0-6.0 µM, and the detection limit was 0.03 µM. The excellent properties of the nanoprobe enable its applications in the ratiometric fluorescence imaging of endogenous ONOO- in cell mitochondria.


Assuntos
Ácido Peroxinitroso , Pontos Quânticos , Corantes Fluorescentes , Mitocôndrias , Imagem Óptica
20.
Mikrochim Acta ; 188(5): 158, 2021 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-33825048

RESUMO

A self-correcting fluorescent assay of tyrosinase (TYR) was developed by utilization of Fe-MIL-88B-NH2 as a peroxidase-like nanozyme and a capture probe. Fe-MIL-88B-NH2 nanozyme was selected as an electron donor, and the oxidization product (dopamine-o-quinone) acts as an energy acceptor. First, TYR catalyzes the oxidation of tyramine hydrochloride to dopamine and then to dopamine-o-quinone. Second, Fe-MIL-88B-NH2 with intrinsic peroxidase-like activity decomposes H2O2 to produce ·OH radicals, which further accelerate the oxidation of dopamine to dopamine-o-quinone. Excessive H2O2 and ·OH radicals reduce the interferences from ascorbic acid at the same time providing a self-correcting ability. Dopamine-o-quinone reacts with -NH2 groups on the ligand of Fe-MIL-88B-NH2 through Michael reaction which results in fluorescence quenching. Under 365-nm excitation, the fluorescence emission intensity at 452 nm gradually decreased with increasing TYR concentration varying from 0 to 10 U mL-1. The linear range is from 1 to 5 U mL-1 and the detection limit is 0.05679 U mL-1. This self-correcting fluorescent assay of tyrosinase exhibits good sensitivity and selectivity which is also successfully applied for tyrosinase inhibitor detection. Schematic representation of fluorescent assay for tyrosinase determination based on Fe-MIL-88B-NH2 nanozyme. A self-correcting fluorescent assay for tyrosinase was developed based on the Fe-MIL-88B-NH2 nanozyme.

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