Because of the serological cross-reactivity among flaviviruses, molecular detection methods, such as reverse-transcription polymerase chain reaction (RT-PCR), play an important role in recent Zika outbreak. However, due to limited sensitivity, window RT-PCR for viremia is only about one week after symptom onset. By combining loop-mediated isothermal amplification (LAMP) and AC susceptometry, we demonstrate a rapid homogeneous system virus oligonucleotide. Streptavidin-magnetic nanoparticles...

In this letter, we demonstrate a new principle for diagnostics based on DNA sequence detection using single-stranded oligonucleotide tagged magnetic nanobeads. The target is recognized and volume-amplified to large coils by circularization of linear padlock probes through probe hybridization ligation, followed rolling circle amplification (RCA). Upon the nanobeads in RCA coils, complex magnetization spectrum beads changes dramatically, induced attached molecules. We show that can be used...

Superstructural assembly of magnetic nanoparticles enables approaches to biosensing by combining specially tailored properties superstructures and the particular advantages associated with a or optomagnetic read-out such as low background signal, easy manipulation, cost-efficiency, potential for bioresponsive multiplexing. Herein, we demonstrate sensitive rapid miRNA detection method based on read-out, duplex-specific nuclease (DSN)-assisted target recycling, use multilayer core-satellite...

We demonstrate detection of DNA coils formed from a Vibrio cholerae target at picomolar concentrations using novel optomagnetic approach exploiting the dynamic behavior and optical anisotropy magnetic nanobead (MNB) assemblies. establish that complex second harmonic transmission spectra MNB suspensions measured upon application weak uniaxial AC field correlate well with rotation dynamics individual MNBs. Adding analyte to solution leads formation permanent clusters, namely, suppression...

The possibility for conducting multiplex detection of DNA-sequences using the volume-amplified magnetic nanobead assay [Stromberg, M.; Goransson, J.; Gunnarsson, K.; Nilsson, Svedlindh, P. and Strømme, M. Nano Lett. 2008 , 8, 816-821] was investigated. In this methodology, a batch consisting mixture several sizes probe-tagged beads used types targets in same compartment. Furthermore, nonlinear least-squares deconvolution procedure composite imaginary part complex magnetization vs frequency...

Benefiting from the specially tailored properties of building blocks as well scaffolds, DNA-assembled core–satellite superstructures have gained increasing interest in drug delivery, imaging, and biosensing. The load satellites plays a vital role superstructures, it determines signal intensity response to biological/physical stimulation/actuation. Herein, for first time, we utilize on-particle rolling circle amplification (RCA) prepare rapidly responsive magnetic with high nanoparticle (MNP)...

The ability to detect and analyze the state of magnetic labels with high sensitivity is crucial importance for developing biosensors. In this work, we demonstrate, first time, a ferromagnetic resonance (FMR) based homogeneous volumetric biosensor label detection. Two different isothermal amplification methods, i.e., rolling circle (RCA) loop-mediated (LAMP), are adopted combined standard electron paramagnetic (EPR) spectrometer FMR biosensing. For RCA-based biosensor, binding RCA products...

For the first time DNA coils formed by rolling circle amplification are quantified on‐chip Brownian relaxation measurements on magnetic nanobeads using a magnetoresistive sensor. No external fields required besides field arising from current through sensor, which makes setup very compact. Limits of detection down to 500 Bacillus globigii spores and 2 pM Vibrio cholerae demonstrated, same order magnitude or lower than those achieved previously commercial macro‐scale AC susceptometer. The...

DNA-assembled nanoparticle superstructures offer numerous bioresponsive properties that can be utilized for point-of-care diagnostics. Functional DNA sequences such as deoxyribozymes (DNAzymes) provide novel strategies and further extend the application of superstructures. In this work, we describe a microRNA detection biosensor combines magnetic (MNP) assemblies with DNAzyme-assisted target recycling. The scaffolds MNP contain substrate DNAzyme form cleavage catalytic structures in presence...

A turn-on competitive immunoassay using a low-cost Blu-ray optomagnetic setup and two differently sized magnetic particles (micron-sized acting as capture nano-sized detection particles) is here presented. For Salmonella detection, limit of 8×104 CFU/mL achieved within total assay time 3 h. The combination strategy an not only enables read-out format, but also results in sensitivity about factor 20 times lower than volumetric stray field device based immunoassays. improvement enabled by the...

Magnetorelaxometry measurements on suspensions of magnetic beads are demonstrated using a planar Hall effect sensor chip embedded in microfluidic system. The alternating field used for magnetizing the is provided by bias current and complex susceptibility spectra recorded as 2nd harmonic response. signal appears when bead suspension injected, it scales with concentration, follows Cole-Cole expression Brownian relaxation. resembles that from conventional magnetorelaxometry done same samples...

Detection of a Vibrio cholerae DNA-sequence using an optomagnetic read-out exploiting the dynamic behavior magnetic nanobeads along with two turn-on data analysis approaches is demonstrated. The method uses weak uniaxial AC field varying frequency applied perpendicular to optical path and measures modulation laser light passing through cuvette containing sample oligonucleotide-tagged beads macromolecular coils single-stranded DNA. DNA are formed upon padlock probe ligation followed by...

Rapid and sensitive diagnostic methods based on isothermal amplification are ideal substitutes for PCR in out-of-lab settings. However, there bottlenecks terms of establishing low-cost user-friendly readout schemes. Combining the high efficiency loop-mediated (LAMP) with an optomagnetic nanoparticle-based system, we demonstrate ultrasensitive rapid detection Newcastle disease virus RNA. Biotinylated amplicons LAMP reverse transcription (RT-LAMP) bind to streptavidin-coated magnetic...

In this work, a two-dimensional self-assembled magnetic nanoparticle–graphene oxide (MNP-GO) nanocomposite is reported for the detection of DNA. Single-stranded DNA (ssDNA) coils, generated through rolling circle amplification (RCA) reaction triggered by hybridization target oligos and padlock probes, have strong interaction with MNP-GO nanotags several mechanisms including π–π stacking, hydrogen bonding, van der Waals, electrostatic, hydrophobic interactions. This leads to hydrodynamic size...

Aging phenomena were investigated in three different ferrofluids containing submicron sized magnetic beads consisting of a cluster iron oxide nanoparticles embedded dextrane matrix with primary amine groups on the surface (one fresh sample and one aged during months) plain (only surface, for months), suitable biosensor applications. The main characterization technique used was measurement frequency dependent complex magnetization using superconducting quantum interference device....

Abstract Bioassays relying on magnetic read‐out using probe‐tagged nanobeads are potential platforms for low‐cost biodiagnostic devices pathogen detection. For optimal assay performance it is crucial to apply an easy, efficient and robust bead‐probe conjugation protocol. In this paper, sensitive (1.5 pM) singleplex detection of bacterial DNA sequences demonstrated in a portable AC susceptometer by nanobead‐based bioassay principle; the volume‐amplified nanobead (VAM‐NDA). Two bead sizes, 100...

Loop-targeting detection probes are used to discriminate true positive from spurious DNA amplicons in a real-time optomagnetic LAMP nanobead assay.

An optomagnetic bioassay is optimized by means of extending the linear range in presence larger nanoparticles.

The present work provides the first real-space analysis of nanobead−DNA coil interactions. Immobilization oligonucleotide-functionalized magnetic nanobeads in rolling circle amplified DNA-coils was studied by complex magnetization measurements and transmission electron microscopy (TEM), a statistical number beads hybridized to performed. average per DNA-coil using results from both methods found be around 6 slightly above 2 for samples with 40 130 nm beads, respectively. TEM supported an...

Immobilization characteristics for single-stranded oligonucleotide-functionalized magnetic beads with nominal sizes of 40, 80, 130, and 250 nm in rolling circle amplified (RCA) DNA coils is investigated by employing complex magnetization measurements, dynamic light scattering fluorescence microscopy. It was found that larger a polydisperse bead size distribution more easily immobilize the RCA than do smaller beads. This may be related to higher oligonucleotide surface coverage Furthermore,...

Understanding the binding mechanism between probe-functionalized magnetic nanoparticles (MNPs) and DNA targets or amplification products thereof is essential in optimization of biosensors for detection DNA. Herein, molecular interaction forming hybrid structures upon hybridization DNA-functionalized nanoparticles, exhibiting Brownian relaxation, rolling circle (DNA-coils) investigated by use atomic force microscopy a liquid environment measuring frequency-dependent response modulation light...