Novel gold nanoparticle trimer reporter probe combined with dry-reagent cotton thread immunoassay device for rapid human ferritin test.

We reported here for the first time on the use of cotton thread combined with novel gold nanoparticle trimer reporter probe for low-cost, sensitive and rapid detection of a lung cancer related biomarker, human ferritin. A model system comprising ferritin as an analyte and a pair of monoclonal antibodies was used to demonstrate the proof-of-concept on the dry-reagent natural cotton thread immunoassay device. Results indicated that the using of novel gold nanoparticle trimer reporter probe greatly improved the sensitivity comparing with traditional gold nanoparticle reporter probe on the cotton thread immunoassay device. The assay avoids multiple incubation and washing steps performed in most conventional protein analyses. Although qualitative tests are realized by observing the color change of the test zone, quantitative data are obtained by recording the optical responses of the test zone with a commercial scanner and corresponding analysis software. Under optimal conditions, the cotton thread immunoassay device was capable of measuring 10 ng/mL human ferritin under room temperature which is sensitive enough for clinical diagnosis. Moreover, the sample solution employed in the assays is just 8 µL, which is much less than traditional lateral flow strip based biosensors.

A novel adenosine-based molecular beacon probe for room temperature nucleic acid rapid detection in cotton thread device.

We used cotton thread as substrate to develop a novel room temperature DNA detection device for low-cost, sensitive and rapid detection of a human genetic disease, hereditary tyrosinemia type I related DNA sequences. A novel adenosine based molecular beacon (ABMB) probe modified on gold nanoparticle was used as reporter probe. In the presence of coralyne, a small molecule which can react with adenosines, the ABMB would form a hairpin structure just like traditional molecular beacon used extensively. In the presence of target DNA sequences, the hairpin structure of ABMB modified on gold nanoparticles will be opened and the biotin group modified at one end of the DNA probes will be released and react with the streptavidin immobilized on the test zone of the cotton thread. The response of the thread based DNA test device is linear over the range of 2.5-100 nM complementary DNA. The ability of our developed device for discriminating the single base mismatched DNA related to a human genetic disease, hereditary tyrosinemia type I, was improved comparing with previous report. It is worth mentioning that the whole assay procedure for DNA test is performed under room temperature which simplified the assay procedures greatly.

Disposable dry-reagent cotton thread-based point-of-care diagnosis devices for protein and nucleic acid test.

We report here for the first time by using dry-reagent cotton thread-based point-of-care diagnosis devices for low-cost, sensitive and rapid detection of a lung cancer related biomarker, squamous cell carcinoma antigen (SCCA) and a human genetic disease, hereditary tyrosinemia type I related DNA sequences. A model system comprising SCCA as an analyte and a pair of monoclonal antibodies is used to demonstrate the proof-of-concept on the dry-reagent cotton thread based immunoassay device. An enhancement protocol was employed by using two kinds of gold nanoparticle labels for SCCA test which greatly improved the sensitivity of the device. The assay avoids the multiple incubation and washing steps performed in most conventional protein analyses, which is similar with the lateral flow strip technology. Under optimal conditions, the thread based immunoassay device was capable of measuring 1ng/mL SCCA in 20min which meet the requirement for clinical diagnosis. DNA detection was successfully realized by using a novel adenosine based molecular beacon probe as reporter probes in the cotton thread based device, the linear range is 75-3000fmol which is suitable for quantitative test.

Dry-reagent nucleic acid biosensor based on blue dye doped latex beads and lateral flow strip.

In the manuscript, a quantitative lateral flow nucleic acid biosensor (Lateral flow nucleic acid biosensor, LFNB) based on blue dye doped latex beads was proposed and its feasibility for detecting deoxyribonucleic acid (DNA) in plasma was investigated. A 60-mer DNA sequence (T1) was selected as model to demonstrate the protocol. Blue dyes doped latex bead bearing DNA probe would be captured on the corresponding test line in the presence of target DNA, to form an evident blue band. Although qualitative tests are realized by observing the color change of the test zone, quantitative data are obtained by recording the optical responses of the test zone with a portable "Strip Reader" instrument conveniently. The strip has been applied for the detection of synthesized DNA sample in human plasma sample with a detection limit of 3.75 fmol. Interference was not evident even the target DNA was spiked with 50 µL plasma which indicated the well shielding of the latex bead reporters and quantified chromatographic separations of unwanted materials of the strip comparing with traditional gold nanoparticle based LFNB platforms.