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1.
Mater Sci Eng C Mater Biol Appl ; 104: 109972, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31499999

RESUMO

The combination of non-invasive fluorescence (FL) and magnetic resonance (MR) imaging can compensate for disadvantages in terms of resolution and sensitivity. However, the preparation of dual-mode probes simultaneously exhibiting strong brightness and high MR response is challenging. A multifunctional nanoprobe was synthesized for targeted photoluminescence (PL) and MR dual-modal imaging. It was obtained by conjugating iridium(III) complexes, gadolinium(III) and the peptide arginine-glycine-aspartate (RGD) onto silica nanoparticles (Ir@SiO2-Gd-RGD NPs). They are highly water soluble, have an average diameter of ~50 nm, and emit strong yellowish green PL (with excitation/emission peaks at 380/572 nm). Simultaneously, the nanoprobes exhibit high MR response with a longitudinal relaxation of 7.16 mM-1 s-1. Instead of simple encapsulation, Ir(III) complexes were covalently conjugated to silica matrix to enhance the chemical and photochemical stability of the nanoprobes. The excellent biocompatibility and PL/MR dual modal imaging capability of the NPs is demonstrated using HeLa cells and mice as models.

2.
Anal Chim Acta ; 1044: 29-65, 2018 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-30442405

RESUMO

The pivotal role of microfluidic technology in life science and biomedical research is now widely recognized. Indeed, microfluidics as a research tool is unparalleled in terms of its biocompatibility, robustness, efficient reagent consumption, and controlled fluidic, surface, and structure environments. The controlled environments are essential in assessing the complex behavior of cells in response to microenvironmental cues. The strengths of microfluidics also reside in its amenability to integration with other analytical platforms and its capacity for miniaturization, parallelization and automation of biochemical assays. Following previous review on the applications of microfluidic devices for cell-based assays in 2006, we have monitored the progress in the field and summarized the advances in microfluidic technology from 2007 to 2017, with a focus on microfluidics development for applications in cell manipulation, cell capture and detection, and cell treatment and analysis. Moreover, we highlighted novel commercial microfluidic products for biomedical and clinical purposes that were introduced in the review period. Thus, this review provides a comprehensive source for recent developments in microfluidics and presents a snapshot of its remarkable contribution towards basic biomedical research and clinical science. We recognize that although enormous amounts of evidence have reinforced the promise of microfluidic technology across diverse applications, much remains to be done to realize its full potential in mainstream biomedical science and clinical practice.

3.
Mikrochim Acta ; 185(11): 523, 2018 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-30374608

RESUMO

A zinc(II)-responsive ratiometric fluorescent core-shell nanoprobe (referred to as QPNPs) is described. It consist of an optimized combination of an internal reference dye (TBAP) encapsulated in the core, and a Zn(II)-specific indicator dye (PEIQ) in the shell. The nanoprobe was synthesized via single-step graft copolymerization induced by tert-butyl hydroperoxide at 80 °C. QPNPs exhibit a well-defined core-shell nanostructure and well-resolved dual emissions after photoexcitation at 380 nm. After exposure to Zn(II), the QPNPs display a green fluorescence peaking at ~500 nm that increases with the concentration of Zn(II), while the pink fluorescence of the porphine-derived reference dye peaking at ~650 nm remains unchanged. This results in color change from pink to green and thus enables Zn(II) to be detected both spectroscopically and with bare eyes. Zn(II) can be quantified with a 3.1 nM detection limit. The core-shell structured nanoprobe was also applied to real-time imaging of Zn(II) in living HeLa cells and in zebrafish. This work establishes a reliable approach to synthesize ratiometric fluorescent nanoprobes. It enables such nanoprobes to be prepared also by those not skilled in nanomaterial synthesis. Graphical abstract A zinc(II)-responsive core-shell nanoprobe (referred to as QPNP) is synthesized via single-step graft copolymerization. Zn(II) can be quantitated with a 3.1 nM detection limit by the QPNPs through ratiometric fluorescence strategy (PEIQ as the Zn(II) indicator and TBAP as the reference dye).

4.
Anal Chem ; 90(3): 1992-2000, 2018 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-29293314

RESUMO

Fluorescence (FL)/magnetic resonance (MR) dual-modal imaging nanoprobes are significant not only for cutting edge research in molecular imaging, but also for clinical diagnosis with high precision and accuracy. However, synthesis of FL/MR dual-modal imaging nanoprobes that simultaneously exhibit strong fluorescent brightness and high MR response, long-term colloidal stability with uniform sizes, good biocompatibility and a versatile surface functionality has proven challenging. In this study, the well-defined core-shell structured Gd3+ chelate-conjugated fluorescent polymer nanoparticles (Gd-FPNPs) that consist of rhodamine B (RB)-encapsulated poly(methyl methacrylate) (PMMA) cores and Gd3+ chelate-conjugated branched polyethylenimine (PEI) shells, are facilely synthesized via a one-step graft copolymerization of RB-encapsulated MMA from PEI-DTPA-Gd induced by tert-butyl hydroperoxide (TBHP) at 80 °C for 2 h. The mild synthesis route not only preserves the chemical environment for Gd3+ coordination, but also improves optical properties and chemo-/photostability of RB. A high local concentration of outer surface-chelated Gd3+ and their direct interactions with hydrogen protons endow Gd-FPNPs high longitudinal relaxivity (26.86 mM-1 s-1). The uniform spherical structure of Gd-FPNPs facilitates their biotransfer, and their surface carboxyl and amine groups afford them both long-term colloidal stability and cell-membrane permeability. The excellent biocompatibility and FL/MR dual-modal imaging capability of Gd-FPNPs are demonstrated using HeLa cells and mice as models. All the results confirm that Gd-FPNPs fulfill the design criteria for a high-performance imaging nanoprobe. In addition, this study enables such probes to be prepared also by those not skilled in nanomaterial synthesis, and thus promoting the development of novel functional imaging nanoprobes.

5.
Anal Chim Acta ; 966: 81-89, 2017 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-28372730

RESUMO

The deficiency in rapid and in-field detection methods and portable devices that are reliable, easy-to-use, and low cost, results in the difficulties to uphold the high safety standards in China. In this study, we introduce a rapid and cost-effective smartphone-based method for point-of-need food safety inspection, which employs aptamer-conjugated AuNPs as the colorimetric indicator, and a battery-powered optosensing accessory attached to the camera of a smartphone for transmission images capture. A user-friendly and easy-to-use Android application is developed for automatic digital image processing and result reporting. Streptomycin (STR) is selected as the proof-of-concept target, and its specific quantitation can be realized with a LOD of 12.3 nM (8.97 µg kg-1) using the reported smartphone-based method. The quantitation of STR in honey, milk and tap water confirm the reliability and applicability of the reported method. The extremely high acceptance of smartphone in remote and metropolitan areas of China and ease-of-use of the reported method facilitate active food contaminant and toxicant screening, thus making the implementation of the whole food supply chain monitoring and surveillance possible and hence significantly improving the current Chinese food safety control system.


Assuntos
Colorimetria , Inocuidade dos Alimentos , Smartphone , Animais , China , Água Potável/análise , Mel/análise , Nanopartículas Metálicas , Leite/química , Impressão Tridimensional , Reprodutibilidade dos Testes
6.
Anal Chem ; 89(4): 2561-2568, 2017 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-28192946

RESUMO

Ozone (O3) would be harmful to human skin for its strong oxidizing property, especially when stratum corneum or corneal epithelium is wounded. Imaging the penetration and distribution of ozone at depth is beneficial for studying the influence of ozone on skin or eyes. Here, we introduced a facile method for three-dimensional (3D) imaging of the penetration of O3 into the anterior chamber of an isolated crucian carp eye by using optical coherence tomography (OCT) combined with gold triangular nanoprisms (GTNPs) as the contrast agent and molecular probe. We illustrated the specific response of GTNPs to ozone and demonstrated that GTNPs can function as an efficient nanoprobe for sensing O3. The stabilities of GTNPs in different biologic solutions, as well as the signal intensity of GTNPs on an OCT imaging system, were investigated. Visualization of 3D penetration and distribution of O3 in the biologic tissue was proved for the first time. The quantitative analysis of O3 diffusion in the anterior chamber of the fish eye revealed a penetration depth of 311 µm within 172 min. Due to the strong scattering, near-infrared extinction band, and easy functionalization of GTNPs, they could further serve as nanoprobes for 3D OCT or multimodal imaging of other molecules or ions in the future.

7.
Lab Chip ; 17(2): 209-226, 2017 01 17.
Artigo em Inglês | MEDLINE | ID: mdl-27991629

RESUMO

Nanoparticles have drawn significant attention in biomedicine due to their unique optical, thermal, magnetic and electrical properties which are highly related to their size and morphologies. Recently, microfluidic systems have shown promising potential to modulate critical stages in nanosynthesis, such as nucleation, growth and reaction conditions so that the size, size distribution, morphology, and reproducibility of nanoparticles are optimized in a high throughput manner. In this review, we put an emphasis on a decade of developments of microfluidic systems for engineering nanoparticles in various applications including imaging, biosensing, drug delivery, and theranostic applications.


Assuntos
Materiais Biocompatíveis/síntese química , Técnicas de Química Sintética/instrumentação , Dispositivos Lab-On-A-Chip , Nanopartículas , Nanotecnologia/instrumentação , Materiais Biocompatíveis/química , Nanopartículas/química
8.
Mater Sci Eng C Mater Biol Appl ; 69: 561-8, 2016 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-27612748

RESUMO

In this study, a highly sensitive and selective fluorescent Zn(2+) probe which exhibited excellent biocompatibility, water solubility, and cell-membrane permeability, was facilely synthesized in a single step by grafting polyethyleneimine (PEI) with quinoline derivatives. The primary amino groups in the branched PEI can increase water solubility and cell permeability of the probe PEIQ, while quinoline derivatives can specifically recognize Zn(2+) and reduce the potential cytotoxicity of PEI. Basing on fluorescence off-on mechanism, PEIQ demonstrated excellent sensing capability towards Zn(2+) in absolute aqueous solution, where a high sensitivity with a detection limit as low as 38.1nM, and a high selectivity over competing metal ions and potential interfering amino acids, were achieved. Inspired by these results, elementary logic operations (YES, NOT and INHIBIT) have been constructed by employing PEIQ as the gate while Zn(2+) and EDTA as chemical inputs. Together with the low cytotoxicity and good cell-permeability, the practical application of PEIQ in living cell imaging was satisfactorily demonstrated, emphasizing its wide application in fundamental biology research.


Assuntos
Lógica , Imagem Molecular/métodos , Polietilenoimina/química , Quinolinas/química , Zinco/metabolismo , Células HeLa , Humanos , Espaço Intracelular/metabolismo , Espectroscopia de Prótons por Ressonância Magnética
9.
ACS Appl Mater Interfaces ; 8(14): 9472-82, 2016 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-27007856

RESUMO

In this study, two new functionalized polyethylenimine (PEI), PEIR and PEIQ, have been synthesized by covalently conjugating rhodamine 6G (R6G) or 8-chloroacetyl-aminoquinoline (CAAQ) and have been investigated for their sensing capabilities toward metal ions and anions basing on fluorescence on-off and off-on mechanisms. When triggered by protons, metal ions, or anions, functionalized PEIs can behave as a fluorescence switch, leading to a multiaddressable system. Inspired by these results, functionalized PEI-based logic systems capable of performing elementary logic operations (YES, NOT, NOR, and INHIBIT) and integrative logic operations (OR + INHIBIT) have been constructed by observing the change in the fluorescence with varying the chemical inputs such as protons, metal ions, and anions. Due to its characteristics, such as high sensitivity and fast response, developing functionalized PEI as a new material to perform logic operations may pave a new avenue to construct the next generation of molecular devices with better applicability for biomedical research.


Assuntos
Computadores Moleculares , Polietilenoimina/química , Aminoquinolinas/química , Fluorescência , Íons/química , Metais/química , Polietilenoimina/síntese química , Prótons , Rodaminas/química
10.
Mater Sci Eng C Mater Biol Appl ; 61: 207-13, 2016 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-26838842

RESUMO

Dopamine plays a very important role in biological systems and has a direct relationship with the ability of learning and cognition, human desires, feelings and mental state, as well as motor functions. Traditional methods for the detection of dopamine are complicated and time-consuming, therefore it is necessary to explore rapid and accurate detection of dopamine with high sensitivity and specificity. Herein we report a dual-mode system of colorimetric and fluorometric analyses based on gold nanoparticles (AuNPs) and aptamers specifically targeting dopamine. Aptamers modified with the fluorophore were used as dopamine specific recognition probe and the sensing mechanism is based on the color change of AuNPs and the fluorescence recovery of fluorophore conjugated on the aptamers in the presence of dopamine. The addition of aptamers into AuNPs colloid solution would prevent the AuNPs from aggregation in the high-salt solution. The close distance between AuNPs and fluorophore conjugated on the aptamers would lead to the quenching of fluorescence signal. In the presence of dopamine, the conformation of the aptamers and the inter-particle distance would be changed, leading to the aggregation of AuNPs, which subsequently results in color change from red to blue and fluorescence signal recovery. The dual-mode sensing system demonstrated high specificity towards dopamine with the detection limit as low as 78.7 nM. The sensing system reflects on its simplicity as no surface functionalization is required for the nanoparticles, leading to less laborious and more cost-effective synthesis. The reaction time is only 6 min, demonstrating a simple approach for rapid analysis of dopamine. More importantly, the sensing system allows the detection of dopamine in both aqueous solution and complicated biological sample with sensitive response, illustrating the feasibility and reliability for the potential applications in clinical and biomedical analysis in the future.


Assuntos
Dopamina/sangue , Ouro/química , Nanopartículas Metálicas/química , Colorimetria/métodos , Fluorometria/métodos , Humanos
11.
Nanoscale ; 8(1): 500-7, 2016 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-26676688

RESUMO

Obtaining tunable photoluminescence (PL) with improved emission properties is crucial for successfully implementing fluorescent carbon nanodots (fCDs) in all practical applications such as multicolour imaging and multiplexed detection by a single excitation wavelength. In this study, we report a facile hydrothermal approach to adjust the PL peaks of fCDs from blue, green to orange by controlling the surface passivation reaction during the synthesis. This is achieved by tuning the passivating reagents in a step-by-step manner. The as-prepared fCDs with narrow size distribution show improved PL properties with different emission wavelengths. Detailed characterization of fCDs using elemental analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy suggested that the surface chemical composition results in this tunable PL emission. Surface passivation significantly alters the surface status, resulting in fCDs with either stronger surface oxidation or N element doping that ultimately determine their PL properties. Further experiments suggested that the as-prepared orange luminescent fCDs (O-fCDs) were sensitive and specific nanosensing platforms towards Fe(3+) determination in a complex biological environment, emphasizing their potential practical applications in clinical and biological fields.


Assuntos
Carbono/química , Ferro/análise , Pontos Quânticos/química , Ferro/química
12.
Biosens Bioelectron ; 71: 186-193, 2015 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-25909338

RESUMO

In this study, a novel approach for ultrasensitive detection and rapid high-throughput identification of a panel of common foodborne pathogens with the naked eyes is presented. As a proof-of-concept application, a multiple pathogen analysis array is fabricated through immobilizing three specific polyT-capture probes which can respectively recognize rfbE gene (Escherichia coli O157:H7), invA gene (Salmonella enterica), inlA gene (Listeria monocytogenes) on the plastic substrates. PCR has been developed for amplification and labeling target genes of rfbE, invA, inlA with biotin. The biotinated target DNA is then captured onto the surface of plastic strips through specific DNA hybridization. The succeeding staining of biotinated DNA duplexes with avidin-horseradish peroxidise (AV-HRP) and biotinated anti-HRP antibody greatly amplifies the detectable signal through the multiple cycle signal amplification strategy, and thus realizing ultrasensitive and specific detection of the above three pathogens in food samples with the naked eyes. Results showed approximately 5 copies target pathogenic DNA could be detected with the naked eyes. This simple but very efficient colorimetric assay also show excellent anti-interference capability and good stability, and can be readily applied to point-of-care diagnosis.


Assuntos
Colorimetria/instrumentação , Escherichia coli O157/isolamento & purificação , Contaminação de Alimentos/análise , Microbiologia de Alimentos , Listeria monocytogenes/isolamento & purificação , Salmonella enterica/isolamento & purificação , Técnicas Biossensoriais/instrumentação , Colorimetria/economia , DNA Bacteriano/análise , DNA Bacteriano/genética , Escherichia coli O157/genética , Microbiologia de Alimentos/economia , Microbiologia de Alimentos/instrumentação , Humanos , Limite de Detecção , Listeria monocytogenes/genética , Análise de Sequência com Séries de Oligonucleotídeos/economia , Análise de Sequência com Séries de Oligonucleotídeos/instrumentação , Reação em Cadeia da Polimerase/economia , Reação em Cadeia da Polimerase/instrumentação , Salmonella enterica/genética , Fatores de Tempo
13.
Mater Sci Eng C Mater Biol Appl ; 46: 32-40, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25491957

RESUMO

It has been well-established that nanomaterials provide a robust framework into which two or more functional moieties can be integrated to offer multifunctional and synergetic applications. We report here the facile synthesis and systematical investigation of the luminomagnetic core-shell nanoparticles (NPs) with the magnetic Fe3O4 core coated with a silica shell incorporating fluorescent [Ru(bpy)3](2+). The luminomagnetic NPs were monodisperse and spherical in shape with a diameter of 60±10 nm. The luminomagnetic NPs possessed not only the desirable optical signature of Ru(bpy)3(2+) but also the distinctive magnetic profile of Fe3O4, where a strong red-orange emission and the super-paramagnetic characteristics with the saturation magnetization values ca. 10 emu/g were observed for the luminomagnetic NPs. As revealed by Alamar blue assay and flow cytometry analysis, the Fe3O4 NPs decrease the cell viability of HepG2 by ca. 10%, while an increase by ca. 10% on HepG2 cell proliferation was revealed after the silica shell was coated onto Fe3O4 NPs, suggesting that the silica shell serves as a protective layer to increase the biocompatibility of the luminomagnetic NPs. Confocal laser scanning microscopy, transition electron microscopy and magnetic resonance (MR) images confirmed that the luminomagnetic NPs can enter into the interiors of HepG2 cells without damage, highlighting their capabilities for simultaneous optical fluorescence imaging and T2 MR imaging. Taking advantage of versatility of silica shell towards different surface modification protocols, the luminomagnetic NPs were successfully functionalized with epidermal growth factor receptor (EGFR) antibody for HepG2 cell recognition. All the results illustrated that the luminomagnetic NPs should be a potential candidate for future cancer diagnosis and therapy.


Assuntos
Materiais Biocompatíveis/química , Substâncias Luminescentes/química , Nanopartículas de Magnetita/química , 2,2'-Dipiridil/análogos & derivados , 2,2'-Dipiridil/química , 2,2'-Dipiridil/farmacologia , Antineoplásicos/química , Antineoplásicos/farmacologia , Materiais Biocompatíveis/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Células Hep G2 , Humanos , Substâncias Luminescentes/farmacologia , Espectroscopia de Ressonância Magnética , Compostos Organometálicos/química , Compostos Organometálicos/farmacologia
14.
Lab Chip ; 14(20): 3993-9, 2014 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-25140880

RESUMO

We have developed a microfluidic device for the continuous separation of small molecules from a protein mixture and demonstrated its practical use in the study of protein-ligand binding, a crucial aspect in drug discovery. Our results demonstrated dose-dependent binding between bovine serum albumin (BSA) and its small-molecule site marker, Eosin Y (EY), and found that the binding reached a plateau when the BSA : EY ratio was above 1, which agreed with the eosin binding capacity of BSA reported in literature. By streamline control using a combination of two fundamental building blocks (R and L nodes) with a microdevice operated at a high flow rate (up to 1300 µL h(-1)), a solution barrier was created to "filter" off protein/protein-ligand complexes such that the small unbound molecules were isolated and quantified easily. The percentage decrease of small molecules with increasing protein concentration indicated the presence of binding events. Several fluorophores with different molecular weights were used to test the performance of the microfluidic "filter", which was tunable by 1) the total flow rate, and/or 2) the flow distribution ratio between the two device inlets; both were easily controllable by changing the syringe pump settings. Since the microdevice was operated at a relatively high flow rate, aliquots were easily recovered from the device outlets to facilitate off-chip detection. This microfluidic design is a novel and promising tool for preliminary drug screening.


Assuntos
Amarelo de Eosina-(YS)/química , Técnicas Analíticas Microfluídicas , Soroalbumina Bovina/química , Animais , Bovinos , Ligantes , Técnicas Analíticas Microfluídicas/instrumentação
15.
Biosens Bioelectron ; 61: 397-403, 2014 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-24914851

RESUMO

The integration of unique characteristics of nanomaterials with highly specific recognition elements, such as biomolecules and organic molecules, are the foundation of many novel nanoprobes for bio/chemical sensing and imaging. In the present report, branched polyethylenimine (PEI) was grafted with 8-chloroacetyl-aminoquinoline to synthesize a water-soluble and biocompatible quinoline-based Zn(2+) probe PEIQ. Then the PEIQ was covalently conjugated to [Ru(bpy)3](2+)-encapsulated SiNPs to obtain the ratiometric fluorescence nanoprobe which exhibits a strong fluorescence emission at 600 nm and a negligible fluorescence emission at 500 nm in the absence of Zn(2+) upon a single wavelength excitation. After the addition of different amounts of Zn(2+), the fluorescence intensity at 500 nm increased continuously while the fluorescence intensity at 600 nm remained stable, thus changing the dual emission intensity ratios and displaying continuous color changes from red to green which can be clearly observed by the naked eye. The nanoprobe exhibits good water dispersivity, biocompatibility and cell permeability, high selectivity over competing metal ions, and high sensitivity with a detection limit as low as 0.5 µM. Real-time imaging of Zn(2+) in A549 cells has also been realized using this novel nanoprobe.


Assuntos
2,2'-Dipiridil/análogos & derivados , Aminoquinolinas/química , Corantes Fluorescentes/química , Imagem Óptica/métodos , Polietilenoimina/química , Zinco/análise , 2,2'-Dipiridil/química , Técnicas Biossensoriais/métodos , Cátions/análise , Linhagem Celular , Complexos de Coordenação , Fluorescência , Humanos , Microscopia de Fluorescência/métodos , Espectrometria de Fluorescência/métodos
16.
Food Chem ; 153: 371-7, 2014 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-24491742

RESUMO

VitaFast(®) test kits designed for the microbiological assay in microtiter plate format can be applied to quantitative determination of B-group water-soluble vitamins such as vitamin B12, folic acid and biotin, et al. Compared to traditional microbiological methods, VitaFast(®) kits significantly reduce sample processing time and provide greater reliability, higher productivity and better accuracy. Recently, simultaneous determination of vitamin B12, folic acid and biotin in one sample is urgently required when evaluating the quality of infant formulae in our practical work. However, the present sample preparation protocols which are developed for individual test systems, are incompatible with simultaneous determination of several analytes. To solve this problem, a novel "three-in-one" sample preparation method is herein developed for simultaneous determination of B-group water-soluble vitamins using VitaFast(®) kits. The performance of this novel "three-in-one" sample preparation method was systematically evaluated through comparing with individual sample preparation protocols. The experimental results of the assays which employed "three-in-one" sample preparation method were in good agreement with those obtained from conventional VitaFast(®) extraction methods, indicating that the proposed "three-in-one" sample preparation method is applicable to the present three VitaFast(®) vitamin test systems, thus offering a promising alternative for the three independent sample preparation methods. The proposed new sample preparation method will significantly improve the efficiency of infant formulae inspection.


Assuntos
Métodos Analíticos de Preparação de Amostras/métodos , Ácido Fólico/análise , Ácido Fólico/isolamento & purificação , Fórmulas Infantis/química , Vitamina B 12/análise , Vitamina B 12/isolamento & purificação , Métodos Analíticos de Preparação de Amostras/instrumentação , Técnicas Biossensoriais/métodos , Ácido Fólico/metabolismo , Lactobacillus/metabolismo , Kit de Reagentes para Diagnóstico , Solubilidade , Vitamina B 12/metabolismo
17.
Nanomedicine ; 10(6): 1153-63, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24566272

RESUMO

UNLABELLED: Mesenchymal stem cells (MSC) offer an optimal source for bone tissue engineering due to their capability of undergoing multilineage differentiation, where the mechanical properties of the microenvironment of MSCs are vital for osteochondral formation. However, the mechanisms of how mechanical and microenvironmental cues control osteogenesis and chondrogenesis are yet to be elucidated. In this study, we investigated the effects of vertically aligned silicon nanowire (SiNW) array on the differentiation of MSCs and the associated molecular mechanisms involved in osteogenesis and chandrogenesis. The results showed that the microenvironment of SiNW array activated a number of mechanosensitive pathways (including Integrin, TGF-ß/BMP, Akt, MAPK, Insulin, and Wnt pathways) in MSCs, which converged to stimulate the osteogenesis and chondrogenesis via the Ras-Raf-MEK-ERK cascade. FROM THE CLINICAL EDITOR: This study reports on the mechanisms and microenvironmental influence of osteogenesis and chondrogenesis by mesenchymal stem cells interacting with vertically aligned silicon nanowire scaffolds.


Assuntos
Células-Tronco Mesenquimais/citologia , Nanofios/química , Silício/química , Tecidos Suporte/química , Animais , Diferenciação Celular , Células Cultivadas , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Células-Tronco Mesenquimais/metabolismo , Camundongos , Nanofios/ultraestrutura , Osteogênese , Transdução de Sinais
18.
Biosens Bioelectron ; 56: 39-45, 2014 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-24462829

RESUMO

Glutathione (GSH) plays key roles in biological systems and serves many cellular functions. Since biothiols all incorporate thiol, carboxylic and amino groups, discriminative detection of GSH over cysteine (Cys) and homocysteine (Hcy) is still challenging. We herein report a dual-mode nanosensor with both colorimetric and fluorometric readout based on carbon quantum dots and gold nanoparticles for discriminative detection of GSH over Cys/Hcy. The proposed sensing system consists of AuNPs and fluorescent carbon quantum dots (CQDs), where CQDs function as fluorometric reporter, and AuNPs serve a dual function as colorimetric reporter and fluorescence quencher. The mechanism of the nanosensor is based on two distance-dependent phenomenons, color change of AuNPs and FRET. Through controlling the surface properties of as-prepared nanoparticles, the addition of CQDs into AuNPs colloid solution might induce the aggregation of AuNPs and CQDs, leading to AuNPs color changing from red to blue and CQDs fluorescence quench. However, the presence of GSH can protect AuNPs from being aggregated and enlarge the inter-particle distance, which subsequently produces color change and fluorescent signal recovery. The nanosensor described in this report reflects on its simplicity and flexibility, where no further surface functionalization is required for the as-prepared nanoparticles, leading to less laborious and more cost-effective synthesis. The proposed dual-mode nanosensor demonstrated highly selectivity toward GSH, and allows the detection of GSH as low as 50 nM. More importantly, the nanosensor could not only function in aqueous solution for GSH detection with high sensitivity but also exhibit sensitive responses toward GSH in complicated biological environments, demonstrating its potential in bioanalysis and biodection, which might be significant in disease diagnosis in the future.


Assuntos
Carbono/química , Glutationa/sangue , Ouro/química , Nanopartículas/química , Pontos Quânticos/química , Técnicas Biossensoriais/métodos , Colorimetria/métodos , Transferência Ressonante de Energia de Fluorescência/métodos , Humanos , Limite de Detecção
19.
Chem Commun (Camb) ; 50(15): 1848-50, 2014 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-24406326

RESUMO

A carbon nanotube (CNT)-based multiple cycle signal amplification strategy has been demonstrated for detection of single-digit foodborne pathogens with the naked eye. In the present design, CNTs are used as carriers for loading numerous horseradish peroxidase (HRP) and concanavalin A (ConA) tags, and multiple cycle signal amplification is achieved through the biotinylated anti-HRP antibody and avidin-HRP.


Assuntos
Técnicas Biossensoriais/métodos , Ensaio de Imunoadsorção Enzimática/métodos , Escherichia coli O157/isolamento & purificação , Microbiologia de Alimentos , Nanotubos de Carbono/química , Salmonella/isolamento & purificação , Avidina/química , Avidina/metabolismo , Concanavalina A/química , Concanavalina A/metabolismo , Peroxidase do Rábano Silvestre/química , Peroxidase do Rábano Silvestre/metabolismo , Limite de Detecção , Carne/microbiologia
20.
Dalton Trans ; 43(7): 2789-98, 2014 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-24336842

RESUMO

Three new mononuclear copper(II) complexes, [Cu(L2)](2+) (1), [Cu(acac)(L)](+) (2), and [Cu(acac-Cl)(L)](+) (3) (L = 2-(4-pyridine)oxazo[4,5-f]1,10-phenanthroline (4-PDOP); acac = acetylacetone; acac-Cl = 3-chloroacetylacetone), have been synthesized and characterized by elemental analysis, high resolution mass spectrometry (Q-TOF), and IR spectroscopy. Two of the complexes were structurally characterized by single-crystal X-ray diffraction techniques. Their interactions with DNA were studied by UV-vis absorption and emission spectra, viscosity, thermal melting, DNA unwinding assay and CD spectroscopy. The nucleolytic cleavage activity of the compounds was carried out on double stranded pBR322 circular plasmid DNA by using a gel electrophoresis experiment in the presence and absence of an oxidant (H2O2). Active oxygen intermediates such as hydroxyl radicals and hydrogen peroxide generated in the presence of L and complexes 1-3 may act as active species for the DNA scission. The cytotoxicity of the complexes against HepG2 cancer cells was also studied.


Assuntos
Complexos de Coordenação/síntese química , Complexos de Coordenação/farmacologia , Cobre/química , Clivagem do DNA/efeitos dos fármacos , DNA/química , DNA/metabolismo , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Antineoplásicos/metabolismo , Antineoplásicos/farmacologia , Bovinos , Técnicas de Química Sintética , Complexos de Coordenação/química , Complexos de Coordenação/metabolismo , Cristalografia por Raios X , Eletroquímica , Etídio/metabolismo , Depuradores de Radicais Livres/farmacologia , Células Hep G2 , Humanos , Conformação de Ácido Nucleico , Desnaturação de Ácido Nucleico
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