Short Carbon Nanotube-Based Delivery of mRNA for HIV-1 Vaccines.

Developing a safe and effective preventive for HIV-1 remains the hope for controlling the global AIDS epidemic. Recently, mRNA vaccines have emerged as a promising alternative to conventional vaccine approaches, primarily due to their rapid development and potential for low-cost manufacture. Despite the advantages of mRNA vaccines, challenges remain, especially due to the adverse effects of the delivery vehicle and low delivery efficiency.

Mucosal Delivery of HIV-1 Glycoprotein Vaccine Candidate Enabled by Short Carbon Nanotubes.

The HIV-1 envelope glycoprotein spike is the target of antibodies, and therefore represents the main viral antigen for antibody-based vaccine design. One of the challenges in HIV-1 vaccine development is finding efficient ways for the immune system to recognize and respond to HIV-1 without establishing an infection. Since HIV-1 enters the body at mucosal surfaces, induction of immune response at these sites is a preferred preventive approach.

LNA Thymidine Monomer Enables Differentiation of the Four Single-Nucleotide Variants by Melting Temperature.

High-resolution melting (HRM) analysis of DNA is a closed-tube single-nucleotide polymorphism (SNP) detection method that has shown many advantages in point-of-care diagnostics and personalized medicine. While recently developed melting probes have demonstrated significantly improved discrimination of mismatched (mutant) alleles from matched (wild-type) alleles, no effort has been made to design a simple melting probe that can reliably distinguish all four SNP alleles in a single experiment. Such a new probe could facilitate the discovery of rare genetic mutations at lower cost.

3D single-molecule tracking enables direct hybridization kinetics measurement in solution.

Single-molecule measurements of DNA hybridization kinetics are mostly performed on a surface or inside a trap. Here we demonstrate a time-resolved, 3D single-molecule tracking (3D-SMT) method that allows us to follow a freely diffusing ssDNA molecule in solution for hundreds of milliseconds or even seconds and observe multiple annealing and melting events taking place on the same molecule. This is achieved by combining confocal-feedback 3D-SMT with time-domain fluorescence lifetime measurement, where fluorescence lifetime serves as the indicator of hybridization.

NanoCluster Beacons Enable Detection of a Single N⁶-Methyladenine.

While N(6)-methyladenine (m(6)A) is a common modification in prokaryotic and lower eukaryotic genomes and has many biological functions, there is no simple and cost-effective way to identify a single N(6)-methyladenine in a nucleic acid target. Here we introduce a robust, simple, enzyme-free and hybridization-based method using a new silver cluster probe, termed methyladenine-specific NanoCluster Beacon (maNCB), which can detect single m(6)A in DNA targets based on the fluorescence emission spectra of silver clusters. Not only can maNCB identify m(6)A at the single-base level but it also can quantify the extent of adenine methylation in heterogeneous samples.

NanoCluster Beacons as reporter probes in rolling circle enhanced enzyme activity detection.

As a newly developed assay for the detection of endogenous enzyme activity at the single-catalytic-event level, Rolling Circle Enhanced Enzyme Activity Detection (REEAD) has been used to measure enzyme activity in both single human cells and malaria-causing parasites, Plasmodium sp. Current REEAD assays rely on organic dye-tagged linear DNA probes to report the rolling circle amplification products (RCPs), the cost of which may hinder the widespread use of REEAD. Here we show that a new class of activatable probes, NanoCluster Beacons (NCBs), can simplify the REEAD assays.

A complementary palette of NanoCluster Beacons.

NanoCluster Beacons (NCBs), which use few-atom DNA-templated silver clusters as reporters, are a type of activatable molecular probes that are low-cost and easy to prepare. While NCBs provide a high fluorescence enhancement ratio upon activation, their activation colors are currently limited. Here we report a simple method to design NCBs with complementary emission colors, creating a set of multicolor probes for homogeneous, separation-free detection.

Fluorescent silver nanoclusters as DNA probes.

Fluorescent silver nanoclusters (few atoms, quantum sized) have attracted much attention as promising substitutes for conventional fluorophores. Due to their unique environmental sensitivities, new fluorescent probes have been developed based on silver nanoclusters for the sensitive and specific detection of DNA. In this review we present the recent discoveries of activatable and color-switchable properties of DNA-templated silver nanoclusters and discuss the strategies to use these new properties in DNA sensing.

DNA/RNA Detection Using DNA-Templated Few-Atom Silver Nanoclusters.

DNA-templated few-atom silver nanoclusters (DNA/Ag NCs) are a new class of organic/inorganic composite nanomaterials whose fluorescence emission can be tuned throughout the visible and near-IR range by simply programming the template sequences. Compared to organic dyes, DNA/Ag NCs can be brighter and more photostable. Compared to quantum dots, DNA/Ag NCs are smaller, less prone to blinking on long timescales, and do not have a toxic core.

Probing quenched dye fluorescence of Cy3-DNA-Au-nanoparticle hybrid conjugates using solution and array platforms.

Tuning the luminescence intensity of fluorophores using nanoparticles has shown great potential for the detection of inorganic metal ions, viruses, and proteins. The enhancement or quenching of a dye's fluorescence intensity is strongly dependent on the spatial separation of the dye from the nanoparticle surface. To extend luminescence probing from the solution platform to the solid-state platform, we explored and performed dye quenching assessment using an array format in this study.

Synthesis and optical properties of 1-alkyl-3-methylimidazolium lauryl sulfate ionic liquids.

We report the synthesis of a new series of imidazolium-based halogen-free ionic liquids 1-alkyl-3-methylimidazolium lauryl sulfates. By reacting 1-methylimidazole (MIM) with butyl, hexyl, octyl, and decyl bromides and exchanging bromide ion with lauryl sulfate anion, a series of ionic liquids [RMIM][C(12)H(25)OSO(3)] were produced. The high purity of these ionic liquids was verified with (1)H-NMR, (13)C-NMR, FT-IR and mass spectrometry (MS), demonstrating the effectiveness of this synthetic approach.