A simple colorimetric detection of telomerase exploiting specific cleavage of exonuclease III coupled with telomeric DNA controlled aggregation of nanogold.

Telomerase activity has piqued scientists' interest for the reason that it has the potential to be employed for early-stage cancer detection, anticancer therapy and studies related to cancer progression and metastasis. Several approaches have been developed to detect telomerase activity. However, these approaches were lengthy, challenging to quantify, of limited sensitivity and prone to polymerase chain reaction (PCR)-related artefacts.

A simple and rapid colorimetric detection of relied on the distance-dependent optical properties of silver nanoparticles.

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 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.

A novel colorimetric biosensor for rapid detection of dengue virus upon acid-induced aggregation of colloidal gold.

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.

Single gold nanoplasmonic sensor for clinical cancer diagnosis based on specific interaction between nucleic acids and protein.

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.

Resonant Rayleigh light scattering of single Au nanoparticles with different sizes and shapes.

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.

Amplification of resonant Rayleigh light scattering response using immunogold colloids for detection of lysozyme.

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.

Rational aspect ratio and suitable antibody coverage of gold nanorod for ultra-sensitive detection of a cancer biomarker.

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.

Size-dependent plasmonic responses of single gold nanoparticles for analysis of biorecognition.

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.

A new method for non-labeling attomolar detection of diseases based on an individual gold nanorod immunosensor.

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.