Ultrasensitive SERS detection of mercury based on the assembled gold nanochains.

Mercuric ions (Hg(2+)) mediate the transformation of single-stranded DNA to form double helical DNA by T-Hg(2+)-T interaction between base pairs. With this strategy, DNA modified gold nanoparticles (Au NPs) were assembled into chains which were displayed remarkable surface-enhanced Raman scattering (SERS) signal. Under optimized conditions, the length of gold nanochains was directly proportional to the mercuric ions concentrations over 0.

Ultrasensitive aptamer-based SERS detection of PSAs by heterogeneous satellite nanoassemblies.

An ultrasensitive method for surface enhanced Raman scattering (SERS) detection of prostate-specific antigens (PSAs) was established based on the aptamer directed core-satellite nanostructures. A limit of detection (LOD) of 4.8 aM for PSA was obtained.

A ligation DNAzyme-induced magnetic nanoparticles assembly for ultrasensitive detection of copper ions.

A novel biosensor for ultrasensitive detection of copper (Cu(2+)) was established based on the assembly of magnetic nanoparticles induced by the Cu(2+)-dependent ligation DNAzyme. With a low limit of detection of 2.8 nM and high specificity, this method has the potential to serve as a general platform for the detection of heavy metal ions.

Asymmetric plasmonic aptasensor for sensitive detection of bisphenol A.

A sensitive plasmonic chirality-based aptasensor for the detection of bisphenol A (BPA) was developed. Asymmetric plasmonic nanoparticle dimers were produced by the hybridization of a BPA aptamer and its complementary sequence modified nanoparticles. Under different concentrations of BPA, the intensity of the chiral signal was varied.

Unexpected chirality of nanoparticle dimers and ultrasensitive chiroplasmonic bioanalysis.

Chiral assemblies of nanoparticles (NPs) are typically constructed with helical or tetrahedral geometries. Simple pairs of NPs are not expected to display chirality due to basic symmetry considerations made under the assumption of their spherical geometry. In this study we demonstrate that assemblies consisting of two metallic NPs do possess chirality and strongly rotate polarization of light.

A Sensitive DNAzyme-Based Chiral Sensor for Lead Detection.

A DNAzyme-based sensor for the determination and quantification of lead ions (Pb) has been established, which combines the recognition and catalysis of DNAzyme with the optical properties of nanomaterials. Circular dichroism (CD) signals were obtained by a DNAzyme-based assembly of asymmetric silver nanoparticle (AgNPs) dimers. A good linear relationship between CD signals and Pb concentration was obtained ranging from 0.

MRI biosensor for lead detection based on the DNAzyme-induced catalytic reaction.

A MRI biosensor for sensitive and specific detection of lead ions (Pb(2+)) was developed based on DNAzyme-induced cleavage of magnetic nanoparticles (MNPs). A low limit of detection (LOD) of 0.05 ng mL(-1) was obtained.

Ligation Chain Reaction based gold nanoparticle assembly for ultrasensitive DNA detection.

A simple and ultrasensitive DNA biosensor was developed utilizing the color and size changes originating from Ligation Chain Reaction (LCR)-based gold nanoparticle assembly as an indicator. Using synthetic DNA of 10-fold serial dilutions as a target, the limit of detection (LOD) was 1.5 aM with a range of DNA concentrations from 0.

Plasmonic Core-Satellites Nanostructures with High Chirality and Bioproperty.

In this Letter, gold nanorods (Au NRs) and gold nanoparticles (Au NPs) were assembled into core-satellites (Au NR-NPs) nanostructures using DNA as the linkers. Circular dichroism (CD) measurements of the nanoassemblies displayed two plasmonic CD (PCD) peaks in the vicinity of the surface plasmon resonance (SPR). Interestingly, the number of Au NPs in the assemblies had a significant influence on the shape and intensity of the CD line.

A PCR based magnetic assembled sensor for ultrasensitive DNA detection.

An ultrasensitive method for DNA detection based on magnetic assembly induced by polymerase chain reaction (PCR) was developed. The sensor showed a low limit of detection (LOD) of 4.26 aM with a wide range of target DNA from 0.

A one-step homogeneous sandwich immunosensor for Salmonella detection based on magnetic nanoparticles (MNPs) and quantum Dots (QDs).

Simple immuno-magnetic separation tandem fluorescent probes based on quantum dots-antibody (QDs-Ab) were developed to detect Salmonella with sensitivity of 500 cfu mL-1. With two monoclonal antibodies, which recognize different antigenic determinant on the surface of Salmonella, we prepared antibody-coated magnetic nanoparticles (MNPs) and conjugates of QDs-Ab. The immune-magnetic beads were verified with high enrichment efficiency for Salmonella (90%).

Femtogram ultrasensitive aptasensor for the detection of Ochratoxin A.

A simple and ultrasensitive method was developed for the detection of Ochratoxin A, utilizing an aptamer as a molecular recognition probe and real-time quantitative PCR (RT-qPCR) amplification of its complementary DNA as signal generators. Under the optimized conditions, the cycle threshold (Ct) increased linearly with 10-fold serial dilutions of Ochratoxin A (OTA) from 5×10⁻⁶ to 5 ng mL⁻¹, with a limit of detection (LOD) of 1 fg mL⁻¹. The specificity of this aptasensor was considered to be excellent, as when tested against four other toxins it produced no obvious Ct value change.

Ultrasensitive detection of melamine based on a DNA-labeled immunosensor.

A DNA-labeled immunosensor for melamine (MEL) detection is presented which combined the exponential amplification and quantitative effect of Real-Time quantitative PCR (RT-qPCR) with the simplicity and specificity of competitive antigen-antibody reaction. An excellent linear relationship between cycle threshold (Ct) and MEL concentration in the range of 0.001-10 pg g⁻¹ was obtained with a limit of detection of 0.