Microfluidic assay without blocking for rapid HIV screening and confirmation.

The essential step for HIV spreading limitation is the screening tests. However, there are multiple disadvantages in current screening assays which need further confirmation test. Herein we developed a rapid HIV assay combining screening and confirmation test by using the microfluidic network assay. Meanwhile, the assay is accelerated by bypassing the step of blocking. We call this method as microfluidic assay without blocking (MAWB). Both the limit of detection and reagent incubation time of MAWB are determined by screening of one model protein pair: ovalbumin and its antibody. The assay time is accelerated about 25% while the limit of detection (LOD) is well kept. Formatting the method in for both HIV screening (testing 8 HIV-related samples) and confirmation (assaying 6 kinds of HIV antibodies of each sample) within 30 min was successful. Fast HIV screening and confirmation of 20 plasma samples were also demonstrated by this method. MAWB improved the assay speed while keeping the LOD of conventional ELISA. Meanwhile, both the accuracy and throughput of MAWB were well improved, which made it an excellent candidate for a quick HIV test for both screening and confirmation. Methods like this one will find wide applications in clinical diagnosis and biochemical analysis based on the interactions between pairs of molecules.

Using self-polymerized dopamine to modify the antifouling property of oligo(ethylene glycol) self-assembled monolayers and its application in cell patterning.

We report a one-step, mild method to modify antifouling oligo(ethylene glycol)-terminated self-assembled monolayers. We demonstrate for the first time that self-polymerized dopamine, previously reported as an underwater adhesive, can be patterned on typical antifouling surfaces by microfluidic patterning or microcontact printing. The patterns can be applied in spatiotemporal cell patterning.

SPRi determination of inter-peptide interaction by using 3D supramolecular co-assembly polyrotaxane film.

Accurate measurement of inter-peptide interactions is beneficial for in-depth understanding disease-related protein folding and peptide aggregation, and further for designing and selecting potential peptide drugs to the target antigen. Herein, we demonstrate a 3D polyrotaxane (PRX) surface for detecting peptides interactions by surface plasmon resonance imaging (SPRi). This surface is supramolecular self-assembly monolayer (SAM) structure fabricated by threading α-cyclodextrans (α-CD) through a linear polyethylene glycol (PEG) chain fixed on gold chip surface to form pseudopolyrotaxane, and further capping the pseudopolyrotaxane with bulky terminated group to form PRX film. The hydroxyl groups of α-CD can provide more active sites to increase molecules immobilization density, and PEG chain has unique protein non-fouling feature. We chose Alzheimer's disease marker ß-amyloid 40 (Aß40) as model peptide, and detected the interaction between it and its inhibitors KLVFFK6 by SPRi. As a striking result, the specific adsorption of KLVFFK6 solution at the concentration of 352µM on Aß40-PRX was 700RU, whereas PEG SAM surface gave no significant binding. Interaction between other lower molecular weight peptides was detected via PRX surface, and the relatively weak interactions (KD=1.73×10(-4)M) between LPFFD (Mw=0.6kDa) and amylin20-29 (Mw=1.0kDa) are successfully detected.