DNA-Based Nanofabrication for Antifouling Applications.

This paper reports antifouling properties of nanostructured SiO2 substrates patterned by DNA lithography. We used DNA triangle nanostructures as templates to produce triangular-shaped trenches ca. 130 nm in size on SiO2 surfaces. Using B. subtilis as a bacterial model, we found that such nanopatterned surface showed a 75% reduction in bacterial adhesion and 72% reduction in biofilm density at 35% surface coverage of the nanoscale triangular trenches. DNA-based nanofabrication can produce high-resolution designer patterns, but aligning these patterns has been one of the major technical challenges for its applications in nanoelectronics. This work demonstrates the potential of DNA-based nanofabrication in antifouling applications, where surface patterning of micro/nanostructures is required but not their precise alignment.

Increasing the stability of DNA nanostructure templates by atomic layer deposition of Al2O3 and its application in imprinting lithography.

We present a method to increase the stability of DNA nanostructure templates through conformal coating with a nanometer-thin protective inorganic oxide layer created using atomic layer deposition (ALD). DNA nanotubes and origami triangles were coated with ca. 2 nm to ca. 20 nm of Al2O3. Nanoscale features of the DNA nanostructures were preserved after the ALD coating and the patterns are resistive to UV/O3 oxidation. The ALD-coated DNA templates were used for a direct pattern transfer to poly(L-lactic acid) films.

Deposition of DNA Nanostructures on Highly Oriented Pyrolytic Graphite.

We report the deposition of DNA origami nanostructures on highly oriented pyrolytic graphite (HOPG). The DNA origami goes through a structural rearrangement and the DNA base is exposed to interact with the graphite surface. Exposure to ambient air, which is known to result in a hydrophilic-to-hydrophobic wetting transition of HOPG, does not significantly impact the deposition yield or the shape deformation of DNA nanostructures. The deposited DNA nanostructures maintain their morphology for at least a week and promote site-selective chemical vapor deposition of SiO2. This process is potentially useful for a range of applications that include but are not limited to nanostructure fabrication, sensing, and electronic and surface engineering.

Continuous monitoring of bisulfide variation in microdialysis effluents by on-line droplet-based microfluidic fluorescent sensor.

We demonstrate a novel fluorescent sensor for real-time and continuous monitoring of the variation of bisulfide in microdialysis effluents by using a nanoparticle-glutathione-fluorescein isothiocyanate (AuNP-GSH-FITC) probe coupled with on-line droplet-based microfluidic chip. The AuNP-GSH-FITC fluorescent probe was firstly developed and used for bisulfide detection in bulk solution by quantitative real-time PCR, which achieved a linear working range from 0.1 µM to 5.0 µM and a limit of detection of ~50 nM. The response time was less than 2 min. With the aid of co-immobilized thiol-polyethylene glycol, the probe exhibited excellent stability and reproducibility in high salinity solutions, including artificial cerebrospinal fluids (aCSF). By adding 0.1% glyoxal to the probe solution, the assay allowed quantification of bisulfide in the presence of cysteine at the micro-molarity level. Using the AuNP-GSH-FITC probe, a droplet-based microfluidic fluorescent sensor was further constructed for online monitoring of bisulfide variation in the effluent of microdialysis. By using fluorescence microscope-charge-coupled device camera as the detector, the integrated microdialysis/microfluidic chip device achieved a detection limit of 2.0 µM and a linear response from 5.0 µM to 50 µM for bisulfide in the tested sample. The method was successfully applied for the on-line measurement of bisulfide variation in aCSF and serum samples. It will be a very useful tool for tracking the variation of bisulfide or hydrogen sulfide in extracellular fluids.

Combination of a modified block PCR and endonuclease IV-based signal amplification system for ultra-sensitive detection of low-abundance point mutations.

By combination of a modified block PCR and endonuclease IV-based signal amplification system, we have developed a novel approach for ultra-sensitive detection of point mutations. The method can effectively identify mutant target sequence immersed in a large background of wild-type sequences with abundance down to 0.03% (for C→A) and 0.005% (for C→G). This sensitivity is among the highest in comparison with other existing approaches and the operating procedures are simple and time saving. The method holds great potential for future application in clinical diagnosis and biomedical research.

A kinetic method for expeditious detection of pyrophosphate anions at nanomolar concentrations based on a nucleic acid fluorescent sensor.

A kinetic method has been developed for highly sensitive and selective detection of pyrophosphate anions (PPi) by using a fluorophore labelled single-stranded-DNA-Al(III) complex system. The facile and spectrum-tunable fluorescent sensor enables rapid detection of PPi in urine and cell lysate solutions without the need for complex pre-cleanup procedures.