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1.
Anal Methods ; 16(18): 2913-2920, 2024 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-38660999

RESUMO

The quick and accurate diagnosis of pathogens has appeared as a pressing issue in clinical diagnostics, environmental monitoring, and food safety. The available assays are suffering from limited capacities in simple, fast, low-cost, and on-site detection to increase prevention and proper treatment. Herein, we address these challenges by developing a simple, speedy, affordable, and ultrasensitive nanoplasmonic biosensor for colorimetric detection of cDNA from staphylococcal RNA relying on the distance-dependent optical features of silver nanostructures for the measurement of color variations and spectral shifts owing to the plasmon coupling generated by the cross-linking accumulation of AgNPs. The method described utilizes silver nanoparticles (AgNPs) immobilized with two different single-stranded oligonucleotides (ssDNA1 and ssDNA2) that specifically recognize the target DNA. Sandwich hybridization of target DNA with ssDNA1 and ssDNA2 induced color variations and spectral shifts of AgNPs, whereas test samples without the target DNA remained yellow as the initial color of colloidal silver. The designed nanoplasmonic biosensor demonstrated high specificity with the detection limit (LOD) of ∼1.8 amol target DNA (∼106 molecules per test) in the broad linear dynamic range from 0.01 to 100 nM, and LOD down to a few cells was attained for amplified bacterial nucleic acids and a linear range from 102 CFU mL-1 to 107 CFU mL-1. The sensing approach showed great potential for the timely diagnosis of pathogens in low-density samples, and it has considerable merits over traditional culture approaches and qPCR techniques.


Assuntos
Colorimetria , Nanopartículas Metálicas , Prata , Staphylococcus aureus , Prata/química , Colorimetria/métodos , Nanopartículas Metálicas/química , Staphylococcus aureus/isolamento & purificação , Técnicas Biossensoriais/métodos , Limite de Detecção , Humanos , DNA Bacteriano/análise
2.
Anal Methods ; 15(32): 3991-3999, 2023 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-37545366

RESUMO

The dengue virus, once transmitted to people through a mosquito bite, causes an infectious disease called dengue fever. Dengue fever can develop into two fatal syndromes, namely dengue shock syndrome and dengue hemorrhagic fever. The existing strategies for detecting dengue infection mainly employ serological immunoassays and a real time PCR technique. Along with the positive features of efficiency, accuracy, and reproducibility, these procedures are limited by being time-consuming, costly, requiring special equipment for analysis, and unable to be carried out at the point-of-care level. Herein, we developed a colorimetric nanosensor for detecting dengue virus in clinical samples that is rapid, accurate, sensitive, and less expensive. The sensing platform relies on the specific binding between the DNA-conjugated AuNPs and genomic RNA of dengue, which results in the DNA-RNA heteroduplex structure formation that turns the gold colloid's ruby red color to blue due to the nano-aggregation in an acidic environment, which can be detected by the naked eye or measuring the absorbance. The DNA probe was designed to bind to a genomic RNA conserved region recognized in all four dengue serotypes. Dengue virus serotype 1 was utilized as a framework for virus detection; the designed nanosensor exhibited great specificity and selectivity, with the detection limit of ∼1 pg µL-1 (∼1.66 × 106 RNA copies per reaction) and time of analysis of about 1 h including the RNA extraction step. The proposed colorimetric nanosensor offers an alternative tool for specific and highly sensitive detection of dengue that eliminates the requirement for thermal cycling and primer sets in PCR-based assays.


Assuntos
Técnicas Biossensoriais , Vírus da Dengue , Dengue , Nanopartículas Metálicas , Humanos , Vírus da Dengue/genética , Dengue/diagnóstico , Colorimetria , Coloide de Ouro , Reprodutibilidade dos Testes , Ouro , Sensibilidade e Especificidade , Reação em Cadeia da Polimerase em Tempo Real , RNA Viral/análise , RNA Viral/genética , DNA
3.
Biosens Bioelectron ; 67: 59-65, 2015 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-24996253

RESUMO

Plasmonic nanomaterials reveal noble optical properties for next-generation biosensors. Nanoplasmonic biosensors have become simple, sensitive, smart, and consistent with advanced healthcare programs requirements. Notably, an individual nanoparticle analysis can yield unique target information, based on which the next-generation biosensor is revolutionary for end-point detection (single or multiplex), and can be functionally extended to biological phenomena monitoring. Here, we present a single nanoplasmonic sensing technology based on localized surface plasmon resonance for label-free and real-time detection of highly reliable cancer markers (mutant gene and telomerase) in clinical samples. The sensor specifically detects mutant DNA, and can detect telomerase from as few as 10 HeLa cells. This approach can be easily translated to detect other pathological targets with high sensitivity and specificity, and monitor key interactions between biomolecules such as nucleic acids and proteins during disease development in real time. This system has great potential to be further developed for on-chip and simultaneous analysis of multiple targets and interactions.


Assuntos
Biomarcadores Tumorais/isolamento & purificação , Técnicas Biossensoriais , Nanopartículas , Neoplasias/diagnóstico , Biomarcadores Tumorais/genética , Ouro/química , Células HeLa , Humanos , Nanopartículas/química , Nanoestruturas/química , Neoplasias/genética , Ácidos Nucleicos/isolamento & purificação , Proteínas/isolamento & purificação , Ressonância de Plasmônio de Superfície , Telomerase/isolamento & purificação
4.
Nanoscale ; 6(4): 2307-15, 2014 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-24413584

RESUMO

Scientific interest in nanotechnology is driven by the unique and novel properties of nanometer-sized metallic materials such as the strong interaction between the conductive electrons of the nanoparticles and the incident light, caused by localized surface plasmon resonances (LSPRs). In this article, we analysed the relationship of the Rayleigh scattering properties of a single Au nanoparticle with its size, shape, and local dielectric environment. We also provided a detailed study on the refractive index sensitivity of three types of differently shaped Au nanoparticles, which were nanospheres, oval-shaped nanoparticles and nanorods. This study helps one to differentiate the Rayleigh light scattering from individual nanoparticles of different sizes and/or shapes and precisely obtain quantitative data as well as the correlated optical spectra of single gold nanoparticles from the inherently inhomogeneous solution of nanoparticles. These results suggest that the shape, size and aspect ratio of Au nanoparticles are important structural factors in determining the resonant Rayleigh light scattering properties of a single Au nanoparticle such as its spectral peak position, scattering-cross-section and refractive index sensitivity, which gives a handle for the choice of gold nanoparticles for the design and fabrication of single nanosensors.


Assuntos
Ouro/química , Luz , Nanopartículas Metálicas/química , Espalhamento de Radiação , Ressonância de Plasmônio de Superfície , Tamanho da Partícula
5.
Small ; 9(20): 3485-92, 2013 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-23606501

RESUMO

A strategy for attomolar-level detection of small molecule-size proteins is reported based on Rayleigh light scattering spectroscopy of individual nanoplasmonic aptasensors by exploiting the outstanding characteristics of gold colloids to amplify the nontransparent resonant signal at ultralow analyte concentrations. The fabrication method utilizes thiol-mediated adsorption of a DNA aptamer on the immobilized Au nanoparticle surface, the interfacial binding characteristics of the aptamer with its target molecules, and the antibody-antigen interaction through plasmonic resonance coupling of the Au nanoparticles. Using lysozyme as a model analyte for disease detection, the detection limit of the aptasensor is ∼7 × 10(3) aM, corresponding to the LSPR λmax shift of ∼2.25 nm. Up to a 380% increase in the localized resonant λmax shift is demonstrated upon antibody binding to the analyte compared to the primary response during signal amplification using immunogold colloids. This enhancement leads to a limit of detection of ∼7 aM, which is an improvement of three orders of magnitude. The results demonstrate substantial promise for developing coupled plasmonic nanostructures for ultrasensitive detection of various biological and chemical analytes.


Assuntos
Anticorpos/imunologia , Coloides/química , Ouro/química , Luz , Muramidase/análise , Espalhamento de Radiação , Humanos , Imunoglobulina G/metabolismo , Nanopartículas Metálicas/ultraestrutura , Tamanho da Partícula , Ligação Proteica , Soroalbumina Bovina/metabolismo , Espectrofotometria Ultravioleta , alfa-Amilases/metabolismo
6.
Lab Chip ; 12(6): 1102-9, 2012 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-22298159

RESUMO

We report a simple, ultra-sensitive, and straightforward method for non-labeling detection of a cancer biomarker, using Rayleigh light scattering spectroscopy of the individual nanosensor based on antibody-antigen recognition and localized surface plasmon resonance (LSPR) λ(max) shifts. By experimentally measuring the refractive index sensitivity of Au nanorods, the Au nanorod with an aspect ratio of ~3.5 was proven optimal for the LSPR sensing. To reduce the steric hindrance effect as well as to immobilize a large amount of ligand on the nanoparticle surface, various mixtures containing different molar ratios of HS(CH(2))(11)(OCH(2)CH(2))(6)OCH(2)COOH and HS(CH(2))(11)(OCH(2)CH(2))(3)OH were applied to form different self-assembled monolayer surfaces. The results showed that the best molar ratio for antibody conjugation was 1 : 10. When using individual Au nanorod sensors for the detection of prostate specific antigen (PSA), the lowest concentration recorded was ~1 aM (~6 × 10(5) molecules), corresponding to LSPR λ(max) shifts of ~4.2 nm. These results indicate that sensor miniaturization down to the nanoscale level, the reduction of steric hindrance, and optimization of size, shape, and aspect ratio of nanorods have led to a significant improvement in the detection limit of sensors.


Assuntos
Anticorpos Imobilizados/química , Ouro/química , Nanotubos/química , Antígeno Prostático Específico/análise , Ressonância de Plasmônio de Superfície/métodos , Anticorpos Imobilizados/imunologia , Humanos , Limite de Detecção , Masculino , Nanotubos/ultraestrutura , Antígeno Prostático Específico/imunologia , Neoplasias da Próstata/diagnóstico
7.
Anal Biochem ; 421(1): 213-8, 2012 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-22146558

RESUMO

We report the use of plasmonic responses of single gold nanoparticles (AuNPs) with various sizes for the analysis of biomolecular recognition. We also describe the relationship between particle size and plasmonic response induced by the binding of receptors and target analytes. To investigate the plasmonic response of AuNPs, Rayleigh light scattering spectra were collected from individual AuNPs using a dark-field microspectroscopy system. Using prostate-specific antigen (PSA) as a model, the linear dynamic range was obtained in the concentration range of 10(-4) to 10 ng/ml, with the smallest detectable concentration at 0.1 pg/ml corresponding to localized surface plasmon resonance (LSPR) λ(max) shifts of approximately 2.95 nm. This result indicates that individual AuNPs can be used for development of a very sensitive, robust, simple, and label-free biosensor to detect protein biomarkers. Furthermore, the method possesses great potential for monitoring other biological interactions.


Assuntos
Nanopartículas Metálicas , Ressonância de Plasmônio de Superfície/métodos , Ouro , Humanos , Luz , Nanopartículas Metálicas/ultraestrutura , Nanotecnologia , Fenômenos Ópticos , Tamanho da Partícula , Antígeno Prostático Específico/análise , Espalhamento de Radiação , alfa 1-Antiquimotripsina
8.
Lab Chip ; 11(15): 2591-7, 2011 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-21670836

RESUMO

Herein, we present the use of a single gold nanorod sensor for detection of diseases on an antibody-functionalized surface, based on antibody-antigen interaction and the localized surface plasmon resonance (LSPR) λ(max) shifts of the resonant Rayleigh light scattering spectra. By replacing the cetyltrimethylammonium bromide (CTAB), a tightly packed self-assembled monolayer of HS(CH(2))(11)(OCH(2)CH(2))(6)OCH(2)COOH(OEG(6)) has been successfully formed on the gold nanorod surface prior to the LSPR sensing, leading to the successful fabrication of individual gold nanorod immunosensors. Using prostate specific antigen (PSA) as a protein biomarker, the lowest concentration experimentally detected was as low as 111 aM, corresponding to a 2.79 nm LSPR λ(max) shift. These results indicate that the detection platform is very sensitive and outperforms detection limits of commercial tests for PSA so far. Correlatively, its detection limit can be equally compared to the assays based on DNA biobarcodes. This study shows that a gold nanorod has been used as a single nanobiosensor to detect antigens for the first time; and the detection method based on the resonant Rayleigh scattering spectrum of individual gold nanorods enables a simple, label-free detection with ultrahigh sensitivity.


Assuntos
Técnicas Biossensoriais , Ouro , Nanotubos , Antígeno Prostático Específico/análise , Ressonância de Plasmônio de Superfície , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Cetrimônio , Compostos de Cetrimônio , Humanos , Imunoensaio/instrumentação , Imunoensaio/métodos , Antígeno Prostático Específico/química , Antígeno Prostático Específico/metabolismo , Sensibilidade e Especificidade , Ressonância de Plasmônio de Superfície/instrumentação , Ressonância de Plasmônio de Superfície/métodos
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