The lipophilic CdSe quantum dot (QD) coated with trioctylphosphine oxide (TOPOQD) can be extracted from chloroform into water upon interaction with macrocyclic glycocluster amphiphile 1. The QD-conjugated and highly fluorescent sugar ball of a size of 15 nm (TOPOQD1) thus solubilized in water readily invades Hela cells via endocytosis. The endocytic activity of TOPOQD1 (15 nm), in light of those of the micellar homoaggregate of 1 (5 nm) and the virus-like 1-DNA conjugate (50 nm) as references, reveals a dramatic size effect (50 > 15 > 5) in the subviral size region. The optimal size at approximately 50 nm indicates that size complementarity which governs molecular recognition in small host-guest systems also plays key roles in the encapsulation of nanometric guest particles by the endocytic vesicles (

Number- and size-controlled macromolecular associations are common in biology with viruses as a typical example. We report here a novel example of artificial viruses, in which the double-helical DNA is coated with 4-nm sized neutral glycocluster nanoparticles (GNPs) with a coating stoichiometry of approximately 2 GNPs per helical pitch (10 base pairs), where GNP arises from micellization of a cone-shaped, quadruple-chain glycocluster amphiphile having eight saccharide moieties with beta-glucoside termini on the calix[4]resorcarene macrocycle. The resulting "glycoviruses" are compactly packed (54 nm in the case of 7040 base-pair plasmid pCMVluc), are well charge-shielded (zeta congruent with approximately 0 mV), and effectively transfect cell cultures without notable cytotoxicity. The use of artificial viral vectors thus allows a new (nonamine/noncationic/nonpolymeric) access to gene delivery, a potential but still tough subject which has been studied extensively over the last 15 years by using viral or amine-based cationic vectors. The remarkable adhesion-manipulation ability of saccharide clusters also provides a strategy of bottom-up construction of nanometric or mesoscopic sizes.

Here we have designed and synthesized ligands that specifically bind with high affinity (K(d) = 53 nM) to the guanine (G)-guanine mismatch, one of four types of single-nucleotide polymorphism (SNP). Detection of the G-G mismatch was performed by a surface plasmon resonance (SPR) assay using a sensor chip carrying the G-G specific ligand on its surface. The accuracy of the G-G mismatch detection by the SPR sensor was demonstrated by a marked SPR response obtained only for the DNA containing the G-G mismatch. DNAs containing G-A and G-T mismatches, as well as a fully matched duplex, produced only a weak response. Furthermore, this assay was found applicable for the detection of SNP existing in PCR amplification products of a 652-nucleotide sequence of the HSP70-2 gene.

We here report a novel example of artificial glycoviral vectors constructed via number- and size-controlled gene (pCMVluc, 7040 bp) coating with micellar glycocluster nanoparticles (GNPs) of calix[4]resorcarene-based macrocyclic glycocluster amphiphiles having eight or five saccharide moieties with terminal alpha-glucose (alpha-Glc), beta-glucose (beta-Glc), or beta-galactose (beta-Gal) residues. The resulting glycoviruses are compactly packed (approximately 50 nm) and well charge-shielded (zeta approximately equal 0 mV), undergo saccharide-dependent (alpha-Glc > beta-Gal >> beta-Glc) self-aggregation, and transfect cell (Hela and HepG2) cultures as triggered by the pinocytic form of endocytosis. The semilogarithmic linear size-activity correlation suggests that size-restricted pinocytosis (<100 nm) is effective only for monomeric viruses. The activities of oligomeric and otherwise poorly active beta-Gal-functionalized viruses toward hepatic HepG2 cells are approximately 10(2)-times higher than expected on the size basis, owing to the receptor-mediated specific pathway involving the asialoglycoprotein receptors on the hepatic cell surfaces. The scope and prospect of artificial glycoviruses are discussed.

We report on the application of a new class of oligonucleotide reporter probes, QUAL probes, that "light up" when a nucleophilic phosphorothioate probe binds adjacent to a dabsyl-quenched probe. These self-ligating DNA probes were used for sequence-specific detection of 16S rRNA in Escherichia coli cells. Strong fluorescence was observed only when the phosphorothioate and quenched dabsyl probes bind side-by-side on a 16S rRNA target. The results demonstrate the use of QUAL probes to detect specific RNA sequences in bacterial cells without enzymes and without washing steps.

The HGF/c-Met pathway is known to play a key role in cancer metastasis. CLN0003_SL1, a 50-mer DNA aptamer that binds to the c-Met protein, was found to inhibit HGF-induced c-Met activation. This aptamer could suppress cancer cell motility in vitro.

Hyperpolarization is a highly promising technique for improving the sensitivity of magnetic resonance chemical probes. Here we report [15N, D9]trimethylphenylammonium as a platform for designing a variety of hyperpolarized magnetic resonance chemical probes. The platform structure shows a remarkably long 15N spin–lattice relaxation value (816 s, 14.1 T) for retaining its hyperpolarized spin state. The extended lifetime enables the detection of the hyperpolarized 15N signal of the platform for several tens of minutes and thus overcomes the intrinsic short analysis time of hyperpolarized probes. Versatility of the platform is demonstrated by applying it to three types of hyperpolarized chemical probes: one each for sensing calcium ions, reactive oxygen species (hydrogen peroxide) and enzyme activity (carboxyl esterase). All of the designed probes achieve high sensitivity with rapid reactions and chemical shift changes, which are sufficient to allow sensitive and real-time monitoring of target molecules by 15N magnetic resonance.

We describe a new fluorescence reporting strategy in which dabsyl, a well-known quencher, activates a hydroxyl group in a probe to convert it to a leaving group. When a nucleophilic phosphorothioate probe binds adjacent to a dabsyl quenched probe, autoligation occurs, releasing the quencher, and lighting up the probes, This signal change can be used to detect single nucleotide differences in DNA without enzymes or reagents.