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1.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 41(1): 152-159, 2024 Feb 25.
Artigo em Zh | MEDLINE | ID: mdl-38403616

RESUMO

A miniaturized, low-cost high-intensity focused ultrasound device is developed for the problems of cross-contamination and uneven sample fragmentation in conventional ultrasound devices. This device generates ultrasonic waves through a concave spherical self-focusing piezoelectric ceramic piece, and creates a cavitation effect in the focusing area to achieve sample fragmentation. The feasibility of the device is demonstrated by physical simulation, then a driving circuit with adjustable power is designed and manufactured to generate 0 ~ 22.4 W acoustic power, and finally paraffin-embedded sample dewaxing experiments are performed to verify the validation of the device. The experimental results show that the dewaxing efficiency and safety of the high-intensity focused ultrasound device is significantly better than those of traditional chemical methods, and this device is comparable with commercial ultrasonic instruments. In summary, the high-intensity focused ultrasound device is expected to be applied in automated nucleic acid extraction and purification equipment and has a broad application prospect in the field of sample pre-processing.


Assuntos
Acústica , Desenho de Equipamento , Simulação por Computador
2.
Opt Lett ; 48(22): 5935-5938, 2023 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-37966756

RESUMO

We present the design and fabrication of an on-chip FBG interrogator based on arrayed waveguide grating (AWG) technology. The spectral overlap between adjacent channels in the integrated AWG is significantly enhanced through a combination approach involving the reduction of the output waveguide spacing and an increase in the input waveguide width. As a result of these design choices, our AWG demonstrates excellent spectral consistency, with spectral cross talk exceeding 30 dB. The interrogator seamlessly combining optical and circuitry components achieves full integration and enables a wide range of interrogation wavelengths, including C-band and L-band. With an interrogation range extending up to 80 nm, it theoretically has the capacity to simultaneously interrogate the wavelengths of 20 FBG sensors. Experimental findings demonstrate an absolute interrogation accuracy of less than 2 pm for the fully integrated interrogator. With its compact size, cost-effectiveness, exceptional precision, and ease of integration, the proposed interrogator holds a substantial promise for widespread application in the realm of FBG sensing.

3.
Analyst ; 148(10): 2375-2386, 2023 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-37129055

RESUMO

Carbon dots (CDs) with red fluorescence emission are highly desirable for use in bioimaging and trace- substance detection, with potential applications in biotherapy, photothermal therapy, and tumor visualization. Most CDs emit green or blue fluorescence, thus limiting their applicability. We report a novel fluorescent detection platform based on high-brightness red fluorescence emission carbon dots (R-CDs) co-doped with nitrogen and bromine, which exhibit pH and oxidized L-glutathione (GSSG) dual-responsive characteristics. The absolute quantum yield of the R-CDs was as high as 11.93%. We discovered that the R-CDs were able to detect acidic pH in live cells and zebrafish owing to protonation and deprotonation. In addition, GSSG was detected in vitro over a broad linear range (8-200 µM) using the R-CDs with excitation-independent emission. Furthermore, cell imaging and bioimaging experiments demonstrated that the R-CDs were highly cytocompatible and could be used as fluorescent probes to target lysosomes and nucleolus. These studies highlight the promising prospects of R-CDs as biosensing tools for bioimaging and trace-substance detection applications.


Assuntos
Pontos Quânticos , Animais , Dissulfeto de Glutationa , Pontos Quânticos/química , Carbono/química , Peixe-Zebra , Corantes Fluorescentes/química , Nitrogênio/química , Concentração de Íons de Hidrogênio
4.
Analyst ; 148(11): 2564-2572, 2023 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-37158319

RESUMO

ß-Carotene is a natural antioxidant that has an indispensable effect on the growth and immunity of the human body. For intracellular and in vitro detection of ß-carotene, N-doped carbon quantum dots (O-CDs) were prepared by co-heating carbonization of 1,5-naphthalenediamine and nitric acid in ethanol solvent for 2 h at 200 °C. O-CDs have longer wavelength orange light emission, with an optimal excitation peak of 470 nm and an optimal emission peak of 590 nm. According to the principle of the internal filtering effect on which the detection system is based, O-CDs present a good linear relationship with ß-carotene within a wide range of 0-2000 µM, and the R2 coefficient of the linear regression equation is 0.999. In addition, O-CDs showed targeting of lysosomes in cell imaging and could be used to detect intracellular lysosomal movement. These experiments show that O-CDs can be used for in vivo and in vitro detection of ß-carotene and can serve as a potential substitute to commercial lysosome targeting probes.


Assuntos
Pontos Quânticos , beta Caroteno , Humanos , Carbono , Nitrogênio , Corantes Fluorescentes , Diagnóstico por Imagem
5.
Sensors (Basel) ; 23(7)2023 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-37050576

RESUMO

Exosomes derived from cancer cells have been recognized as a promising biomarker for minimally invasive liquid biopsy. Herein, a novel sandwich-type biosensor was fabricated for highly sensitive detection of exosomes. Amino-functionalized Fe3O4 nanoparticles were synthesized as a sensing interface with a large surface area and rapid enrichment capacity, while two-dimensional MXene nanosheets were used as signal amplifiers with excellent electrical properties. Specifically, CD63 aptamer attached Fe3O4 nanoprobes capture the target exosomes. MXene nanosheets modified with epithelial cell adhesion molecule (EpCAM) aptamer were tethered on the electrode surface to enhance the quantification of exosomes captured with the detection of remaining protein sites. With such a design, the proposed biosensor showed a wide linear range from 102 particles µL-1 to 107 particles µL-1 for sensing 4T1 exosomes, with a low detection limit of 43 particles µL-1. In addition, this sensing platform can determine four different tumor cell types (4T1, Hela, HepG2, and A549) using surface proteins corresponding to aptamers 1 and 2 (CD63 and EpCAM) and showcases good specificity in serum samples. These preliminary results demonstrate the feasibility of establishing a sensitive, accurate, and inexpensive electrochemical sensor for detecting exosome concentrations and species. Moreover, they provide a significant reference for exosome applications in clinical settings, such as liquid biopsy and early cancer diagnosis.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Exossomos , Nanopartículas , Humanos , Exossomos/química , Molécula de Adesão da Célula Epitelial/metabolismo , Nanopartículas/química , Técnicas Biossensoriais/métodos , Limite de Detecção , Aptâmeros de Nucleotídeos/química
6.
Int J Mol Sci ; 24(7)2023 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-37047789

RESUMO

Nowadays, bacterial infections are attracting great attention for the research and development of new antimicrobial agents. As one of the quinolones, ciprofloxacin (CI) has a broad-spectrum, strong antibacterial effect. However, the clinical use of ciprofloxacin is limited by drug resistance. Ciprofloxacin carbon dots (CCDs) with enhanced antibacterial activity and copper-doped ciprofloxacin carbon dots (Cu-CCDs) were synthesized by a simple hydrothermal method. The results of structural analysis and antibacterial experiments show that CCDs and Cu-CCDs have effective antibacterial properties by retaining the active groups of ciprofloxacin (-COOH, C-N, and C-F), and Cu-CCDs doped with copper have a better antibacterial effect. In addition, experiments have shown that Cu-CCDs show excellent antibacterial activity against E. coli and S. aureus and have good biocompatibility, which indicates that they have great prospects in clinical applications. Therefore, novel modified copper CCDs with broad-spectrum antibacterial activity, which can be used as antibacterial nanomaterials for potential applications in the field of antibacterial drugs, were synthesized in this study.


Assuntos
Carbono , Ciprofloxacina , Ciprofloxacina/farmacologia , Carbono/química , Staphylococcus aureus , Cobre/farmacologia , Escherichia coli , Antibacterianos/química
7.
Entropy (Basel) ; 25(12)2023 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-38136462

RESUMO

Wearable technologies face challenges due to signal instability, hindering their usage. Thus, it is crucial to comprehend the connection between dynamic patterns in photoplethysmography (PPG) signals and cardiovascular health. In our study, we collected 401 multimodal recordings from two public databases, evaluating hemodynamic conditions like blood pressure (BP), cardiac output (CO), vascular compliance (C), and peripheral resistance (R). Using irregular-resampling auto-spectral analysis (IRASA), we quantified chaotic components in PPG signals and employed different methods to measure the fractal dimension (FD) and entropy. Our findings revealed that in surgery patients, the power of chaotic components increased with vascular stiffness. As the intensity of CO fluctuations increased, there was a notable strengthening in the correlation between most complexity measures of PPG and these parameters. Interestingly, some conventional morphological features displayed a significant decrease in correlation, indicating a shift from a static to dynamic scenario. Healthy subjects exhibited a higher percentage of chaotic components, and the correlation between complexity measures and hemodynamics in this group tended to be more pronounced. Causal analysis showed that hemodynamic fluctuations are main influencers for FD changes, with observed feedback in most cases. In conclusion, understanding chaotic patterns in PPG signals is vital for assessing cardiovascular health, especially in individuals with unstable hemodynamics or during ambulatory testing. These insights can help overcome the challenges faced by wearable technologies and enhance their usage in real-world scenarios.

8.
Chem Rec ; 22(4): e202100287, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35020240

RESUMO

The integration of silver nanoparticles (Ag NPs) with mesoporous silica nanoparticles (MSNs) protects the former from aggregation and promotes the controlled release of silver ions, resulting in therapeutic significance on cancer and infection. The unique size, shape, pore structure and silver distribution of silver mesoporous silica nanoparticles (Ag-MSNs) embellish them with the potential to perform combined imaging and therapeutic actions via modulating optical and drug release properties. Here, we comprehensively review the recent progress in the fabrication and application of Ag-MSNs for combination therapies for cancer and infection. We first elaborate on the fabrication of star-shaped structure, core-shell structure, and Janus structure Ag-MSNs. We then highlight Ag-MSNs as a multifunctional nanoplatform to surface-enhanced Raman scattering-based detection, non-photo-based cancer theranostics and photo-based cancer theranostics. In addition, we detail Ag-MSNs for combined antibacterial therapy via drug delivery and phototherapy. Overall, we summarize the challenges and future perspectives of Ag-MSNs that make them promising for diagnosis and therapy of cancer and infection.


Assuntos
Nanopartículas Metálicas , Nanopartículas , Neoplasias , Antibacterianos/química , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Humanos , Nanopartículas Metálicas/química , Nanopartículas Metálicas/uso terapêutico , Nanopartículas/química , Nanopartículas/uso terapêutico , Neoplasias/tratamento farmacológico , Dióxido de Silício/química , Prata/química
9.
Analyst ; 147(11): 2558-2566, 2022 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-35551289

RESUMO

Cellular imaging using carbon dots is an important research method in several fields. Herein, green-emissive carbon quantum dots (G-CDs) with a pretty high absolute quantum yield (QY) were fabricated via a one-step solvothermal method by using m-phenylenediamine and concentrated hydrochloric acid. G-CDs displayed strong green fluorescence with excitation/emission peaks at 460/500 nm, and their absolute quantum yield was as high as 58.65%. Further experiments suggested that the G-CDs we prepared have good solubility, excellent biocompatibility, and the capacity of rapidly imaging HeLa and 4T1 cells. Over expectations, the G-CDs could penetrate cells in only 10 s and the confocal images showed that the G-CDs could target the nucleus of cells. Moreover, by using 920 nm as the excitation wavelength, two-photon imaging has been successfully applied to 4T1 cells, overcoming the inherent limitations of single-photon imaging. The extremely high absolute quantum efficiency, ultra-fast imaging speed, and two-photon imaging capability make the G-CDs have good application potential in biomedical analysis and the clinical diagnostic field.


Assuntos
Pontos Quânticos , Carbono , Corantes Fluorescentes/toxicidade , Humanos , Microscopia de Fluorescência , Pontos Quânticos/toxicidade , Coloração e Rotulagem
10.
Anal Bioanal Chem ; 414(29-30): 8201-8213, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36260128

RESUMO

Formalin-fixed paraffin-embedded (FFPE) tissue samples are routinely used in prospective and retrospective studies. It is crucial to obtain high-quality nucleic acid (NA) from FFPE samples for downstream molecular analysis, such as quantitative polymerase chain reaction (PCR), Sanger sequencing, next-generation sequencing, and microarray, in both clinical diagnosis and basic research. The current NA extraction methods from FFPE samples using chemical solvent are tedious, environmentally unfriendly, and unamenable to automation or field deployment. We present a tool for NA extraction from FFPE samples using a high-intensity focused ultrasound (HIFU) technology. A cartridge strip containing reagents for FFPE sample deparaffinization and NA extraction and purification is operated by an automation tool consisting of a HIFU module, a liquid handling robot unit, and accessories including a thermal block and magnets. The HIFU module is a single concaved piezoelectric ceramic plate driven by a current-mode class-D power amplifier. Based on the ultrasonic cavitation effects, the HIFU module provides highly concentrated energy introducing paraffin emulsification and disintegration. The high quantity and quality of NA extracted using the reported system are evaluated by PCR and compared with the quantity and quality of NA extracted using the current standard methods.


Assuntos
Ácidos Nucleicos , Inclusão em Parafina , Fixação de Tecidos/métodos , Formaldeído/química , Estudos Retrospectivos , Estudos Prospectivos , Automação
11.
J Nanobiotechnology ; 20(1): 181, 2022 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-35392911

RESUMO

Cancer immunotherapy is limited by the immune escape of tumor cells and adverse effects. Photo-immunotherapy, the combination of immunotherapy and phototherapy (such as photodynamic therapy (PDT) and photothermal therapy (PTT)), can improve the effectiveness of immunotherapy in cancer treatment. Here, we first explored mesoporous hexagonal core-shell zinc porphyrin-silica nanoparticles (MPSNs), which are composed of a zinc porphyrin core and a mesoporous silica shell, and exhibit high laser-triggered photodynamic and photothermal activity, as well as outstanding drug loading capacity. In other words, MPSNs can be used not only as excellent photosensitizers for photo-immunotherapy, but also as an ideal drug carrier to achieve more efficient synergy. After loading with R837 (imiquimod, a toll-like receptor-7 agonist), MPSNs@R837 will elicit high-efficiency immunogenic cell death via PDT and PTT, and promote dendritic cell maturation after the PH-responsive release of R837, thereby, inducing tumor-specific immune responses. When combined with a programmed death ligand-1 checkpoint blockade, the photo-immunotherapy system markedly restrains primary tumors and metastatic tumors with negligible systemic toxicity. Therefore, the therapeutic strategy of integrating PTT, PDT and checkpoint blockade, shows great potential for suppressing cancer metastasis.


Assuntos
Nanopartículas , Neoplasias , Fotoquimioterapia , Linhagem Celular Tumoral , Imiquimode , Imunoterapia , Nanopartículas/uso terapêutico , Neoplasias/tratamento farmacológico , Fototerapia , Dióxido de Silício
12.
Sensors (Basel) ; 22(8)2022 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-35458926

RESUMO

Room-temperature phosphorescent (RTP) carbon dots (CDs) have promising applications in bioimaging, anticounterfeiting, and information encryption owing to their long lifetimes and wide Stokes shifts. Numerous researchers are interested in developing highly bright RTP CDs using environmentally friendly and safe synthesis processes (e.g., natural raw materials and zero-pollution production pathways). In this study, we successfully synthesized RTP CDs using a hydrothermal process employing natural vitamins as a raw material, ethylenediamine as a passivator, and boric acid as a phosphorescent enhancer, which is referred to as phosphorescent CD (PCD). The PCDs exhibit both bright blue fluorescence emission and green RTP emission, with a phosphorescence lifetime as long as 293 ms and an excellent green afterglow visible to the naked eye for up to 7.0 s. The total quantum yield is 12.69%. The phosphorescence quantum yield (PQY) is up to 5.15%. Based on the RTP performance, PCDs have been successfully employed for anticounterfeiting and information protection applications. The results of this study provide a green strategy for the scalable synthesis of RTP materials, which is a practical method for the fabrication of RTP materials with high efficiency and long afterglow lifetimes.


Assuntos
Carbono , Radiação , Fluorescência
13.
Small ; 17(26): e2100006, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34081391

RESUMO

Amplifying the chemotherapy-driven immunogenic cell death (ICD) for efficient and safe cancer chemoimmunotherapy remains a challenge. Here, a potential ICD nanoamplifier containing diselenide-bridged mesoporous organosilica nanoparticles (MONs) and chemotherapeutic ruthenium compound (KP1339) to achieve cancer chemoimmunotherapy is tailored. KP1339-loaded MONs show controlled drug release profiles via glutathione (GSH)-responsive competitive coordination and matrix degradation. High concentration of MONs selectively evoked reactive oxygen species production, GSH depletion, and endoplasmic reticulum stress in cancer cells, thus amplifying the ICD of KP1339 and boosting robust antitumor immunological responses. After the combination of PD-L1 checkpoint blockade, cancer cell membrane-cloaked KP1339-loaded MONs not only regress primary tumor growth with low systemic toxicity, but also inhibit distant tumor growth and pulmonary metastasis of breast cancer. The results have shown the potential of coordination and redox dual-responsive MONs boosting amplified ICD for cancer chemoimmunotherapy.


Assuntos
Nanopartículas , Neoplasias , Linhagem Celular Tumoral , Doxorrubicina , Portadores de Fármacos , Sistemas de Liberação de Medicamentos , Humanos , Morte Celular Imunogênica , Neoplasias/tratamento farmacológico , Oxirredução
14.
Opt Express ; 29(9): 13520-13529, 2021 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-33985085

RESUMO

An extremely sensitive multi-order mode refractive index (RI) sensor was fabricated by coupling titanium dioxide nanograss film coated FTO conductive glass with Kretschmann prism. Both calculation and experimental studies were carried out. Theoretical analysis by employing resonant waveguide modes indicated that the maximum sensitivity could be achieved when the mode worked at the weakly-bounded condition. The experimental results showed that for p-polarized and s-polarized light, the sensor exhibited a maximum RI sensitivity of 2938.21 nm/RI unit (RIU) and 1484.39 nm/RIU in the 1st order mode, respectively. Its maximum figure of merit was as high as 77.77. The proposed sensor is promising to be applied in environmental monitoring, immune analysis, nucleic acid test, etc.

15.
Analyst ; 146(15): 4954-4963, 2021 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-34259240

RESUMO

Iron, nitrogen-co-doped carbon quantum dots (Fe,N-CDs) were prepared via a simple one-step hydrothermal method. The quantum yield of fluorescence reached about 27.6% and the blue-emissive Fe,N-CDs had a mean size of 3.76 nm. The as-prepared carbon quantum dots showed good solubility, a high quantum yield, good biocompatibility, low cytotoxicity, and high photostability. Interestingly, the as-prepared Fe,N-CDs exhibited good selectivity and sensitivity toward both hematin and ferric ions, and the limit of detection for hematin and ferric ions was calculated to be about 0.024 µM and 0.64 µM, respectively. At the same time, Fe,N-CDs were used for imaging HeLa cells and showed that most Fe,N-CDs were detained in the lysosome. Thus, this fluorescent probe has potential application in the quantitative detection of hematin or Fe3+ in a complex environment and for determining Fe3+ at the cellular level.


Assuntos
Pontos Quânticos , Carbono , Corantes Fluorescentes/toxicidade , Células HeLa , Hemina , Humanos , Íons , Ferro , Nitrogênio , Pontos Quânticos/toxicidade
16.
Analyst ; 146(7): 2330-2338, 2021 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-33624640

RESUMO

The presence of excessive ROS can cause much harm to the human body and can even cause diseases. Therefore, it is important to detect and remove ROS, but there is no ideal method available for this at present. In this research, using procyanidins, a type of plant extract with strong reducibility, as raw materials, fluorescent carbon dots (CDs) were prepared by a hydrothermal method. The proanthocyanidin-based carbon dots (PCDs) emit a light-green colored light under UV irradiation. The PCDs retain the strong reducibility of procyanidins and are highly water-soluble compared with procyanidins. The PCDs, in addition to having good biocompatibility, also have the superior properties of radical scavenging activity and cell imaging. In in vitro experiments, 1,1-diphenyl-2-picrylhydrazyl (DPPH; 100 µM) was reduced by 30% when PCDs were added up to a concentration of 87.5 µg mL-1. At the same time, the fluorescence quenching correlates with the concentration of hypochlorite and hydrogen peroxide and has a good linearity in the range of 250-2250 nM and 60-180 µM with a detection limit of 3.676 nM and 0.602 µM, respectively. Based on the previously described advantages, PCDs have potential as a biomedicine.


Assuntos
Proantocianidinas , Pontos Quânticos , Carbono , Humanos , Peróxido de Hidrogênio/toxicidade , Proantocianidinas/toxicidade
17.
Luminescence ; 36(8): 1969-1976, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34374196

RESUMO

As the second messenger in cells, calcium ions are indispensable in various physiological activities of the body. In this work, a special red fluorescent carbon dot was designed and synthesized using the secondary hydrothermal method with yttrium, p-phenylenediamine, and ethylene glycol tetraacetic acid as precursors for the detection of calcium ions. The designed carbon dot exhibited bright red fluorescence, and the fluorescence emission wavelength showed good photostability. When the calcium ion concentration was controlled from 0 to 400 µM, the carbon dot tended to respond to fluorescence quenching. At the same time, a test paper experiment was carried out, which proved the potential application of the nano-sensor in detecting calcium ions.


Assuntos
Carbono , Pontos Quânticos , Cálcio , Corantes Fluorescentes , Íons , Espectrometria de Fluorescência , Ítrio
18.
Sensors (Basel) ; 21(9)2021 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-33924954

RESUMO

Two-dimensional (2D) MXenes have shown a great potential for chemical sensing due to their electric properties. In this work, a Ti3C2Tx/polypyrrole (MXene/PPy) nanocomposite has been synthesized and immobilized into a glassy carbon electrode to enable the simultaneous recognition of dopamine (DA) and uric acid (UA) under the interference of ascorbic acid (AA). The multilayer Ti3C2Tx MXene was prepared via the aqueous acid etching method and delaminated to a single layer nanosheet, benefiting the in-situ growth of PPy nanowires. The controllable preparation strategy and the compounding of PPy material remain great challenges for further practical application. A facile chemical oxidation method was proposed to regulate magnitude and density during the forming process of PPy nanowire, which promotes the conductivity and the electrochemical active site of this as-prepared nanomaterial. The MXene/PPy nanocomposite-modified electrode exhibited the selective determination of DA and UA in the presence of a high concentration of AA, as well as a wide linear range (DA: 12.5-125 µM, UA: 50-500 µM) and a low detection limit (DA: 0.37 µM, UA: 0.15 µM). More importantly, the simultaneous sensing for the co-existence of DA and UA was successfully achieved via the as-prepared sensor.


Assuntos
Técnicas Biossensoriais , Nanocompostos , Ácido Ascórbico , Dopamina , Técnicas Eletroquímicas , Eletrodos , Polímeros , Pirróis , Ácido Úrico
19.
Mikrochim Acta ; 187(1): 11, 2019 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-31802246

RESUMO

A metal organic framework obtained from cerium(III) and trimesic acid was pyrolyzed to obtain a novel nanostructure referred to as CeO2/C nanowires. The experimental parameters temperature, precursor and gas atmosphere were optimized. The nanowires show good dispersion and a large number of oxygen vacancies, and this leads to excellent peroxidase-like activity. The nanowires are stable at pH values between 2 and 10, and in the 4-80 °C temperature range. The peroxidase-mimicking activity was exploited in a sensitive colorimetric method for determination of H2O2 by using 3,3',5,5'-tetramethylbenzidine as the chromogenic substrate. The absorbance at 652 nm increases linearly in the 0.5 to 100 µM H2O2 concentration range. If glucose oxidase is added to a solution containing glucose, H2O2 will be enzymatically produced. This was exploited to design a new method for determination of glucose. The optical response is linear in the 1-100 µM glucose concentration range, and the detection limit is 0.69 µM (at S/N = 3). The method was successfully applied to the determination of glucose in serum samples. Graphical abstractCeO2/C nanowires prepared by Ce-MOF pyrolysis show peroxidase-like activity and are able to catalyze the oxidation of tetramethylbenzidine (TMB) by H2O2. This was applied to glucose oxidase-based colorimetruc determination of glucose in human sera.


Assuntos
Materiais Biomiméticos/química , Técnicas Biossensoriais/métodos , Carbono/química , Cério/química , Glucose/análise , Peróxido de Hidrogênio/análise , Nanofios/química , Colorimetria , Glucose/química , Humanos , Peróxido de Hidrogênio/química , Concentração de Íons de Hidrogênio , Compostos Organometálicos/química , Peroxidase/metabolismo , Temperatura
20.
Mikrochim Acta ; 186(9): 605, 2019 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-31385058

RESUMO

Molybdenum disulfide quantum dots (MoS2 QDs) are used in a fluorometric method for the determination of folic acid (FA) based on fluorescence quenching. The MoS2 QDs synthesized by a hydrothermal method possess bright blue fluorescence (with excitation/emission maxima of 325/415 nm), quantum yield of 3.7%, and excellent storage stability in solution (30 days in the refrigerator). Their fluorescence is quenched by FA, and intensity decreases linearly in the 0.1 to 125 µM FA concentration range. The detection limit is 0.1 µM (at S/N = 3), and the relative standard deviation (for n = 5) is 2.8% for 25 µM concentrations of FA. Studies on the quenching mechanism suggest that the effect is due to static quenching. The FA in commercial FA tablets was successfully determined. Graphical abstract Schematic representation of the hydrothermal method for the preparation of molybdenum disulfide quantum dots (MoS2 QDs) with about 2.7 ± 0.5 nm diameter using Na2MoO4 and L-cysteine as Mo and S sources, and the fluorescence method for the determination of folic acid (FA) based on fluorescence quenching of MoS2 QDs.

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