High-resolution MRI of kidney microstructures at 7.05 T with an endo-colonic Wireless Amplified NMR detector

To map the hemodynamic responses of kidney microstructures at 7.05 T with improved sensitivity, a Wireless Amplified NMR Detector (WAND) with cylindrical symmetry was fabricated as an endoluminal detector that can convert externally provided wireless signal at 600.71 MHz into amplified MR signals at 300.33 MHz. When this detector was inserted inside colonic lumens to sensitively observe adjacent kidneys, it could clearly identify kidney microstructures in the renal cortex and renal medullary. Owing to the higher achievable spatial resolution, differential hemodynamic responses of kidney microstructures under different breathing conditions could be individually quantified to estimate the underlying correlation between oxygen bearing capability and local levels of oxygen unsaturation. The WAND's ability to map Blood Oxygen Level Dependent (BOLD) signal responses in heterogeneous microstructures will pave way for early-stage diagnosis of kidney diseases, without the use of contrast agents for reduced tissue retention and toxicity.

Mapping a multiplexed zoo of mRNA expression

In situ hybridization methods are used across the biological sciences to map mRNA expression within intact specimens. Multiplexed experiments, in which multiple target mRNAs are mapped in a single sample, are essential for studying regulatory interactions, but remain cumbersome in most model organisms. Programmable in situ amplifiers based on the mechanism of hybridization chain reaction (HCR) overcome this longstanding challenge by operating independently within a sample, enabling multiplexed experiments to be performed with an experimental timeline independent of the number of target mRNAs. To assist biologists working across a broad spectrum of organisms, we demonstrate multiplexed in situ HCR in diverse imaging settings: bacteria, whole-mount nematode larvae, whole-mount fruit fly embryos, whole-mount sea urchin embryos, whole-mount zebrafish larvae, whole-mount chicken embryos, whole-mount mouse embryos and formalin-fixed paraffin-embedded human tissue sections. In addition to straightforward multiplexing, in situ HCR enables deep sample penetration, high contrast and subcellular resolution, providing an incisive tool for the study of interlaced and overlapping expression patterns, with implications for research communities across the biological sciences.

Development of clinical highly sensitive biosensor-based microarray system

AIM: To develop a sensitive and less instrument-dependent clinical microarray system, in which the microarray signal can be amplified in situ and identified by naked eyes.

METHODS: A group of capture probes for a specific target nucleic acid that was made according to a specific region such as hepatitis B virus (HBV) YMDD motif were arrayed on a thin-film biosensor in a well. A set of detected probes labeled with Au nanoparticle were used to take place of the fluorence labeled probes in classic microarray. The single-strand PCR product was reacted with the capture and detected probes and the deposition of capture-biotin-streptin-Au nanoparticle compound appeared on the surface of the microarray. After in situ amplification in this biosensor based system, we could read the signal on this chips by naked eyes or the digital camera. HBV YMDD mutation detection was applied to identify the sensitivity and specificity of the microarray system.

RESULTS: The signal of the biosensor microarray could be acquired by common camera or naked eyes without any instruments and we could determine the kind of mutation according to the place of the positive signal. The signal-noise ratio were high enough to make the signal absolutely yes and no both in synthesized target oligos and serum samples. The microarray could identify a single base change of selected lamivudine resistance-related mutation as well as multiple mutations at the same time with a high stability, sensitivity, and specificity. We used the biosensor system to test 23 serum samples with YMDD mutation, and the result was coincident with the sequencing result and the signal could be aquired by naked eyes.

CONCLUSION: The thin-film based microarray system which exploits nanoparticle material and biosensor technique can amplify the signal in situ that can be detected by simple instruments or even unaided eyes. Its attractive features are the nonintervention of instrumentation required to detect signal, as well as its high versatility and accuracy.