In this work, we propose a method for constructing silver nanoparticles (AgNPs) on mesoporous silica nanospheres (MSNs) by a DNA-templated process. By in situ formation, the gatekeeper can be easily modulated to meet different degrees of glutathione (GSH) stimuli for location-specific drug release.

Levels of lysosomal copper are tightly regulated in the human body. However, few methods for monitoring dynamic changes in copper pools are available, thus limiting the ability to diagnostically assess the influence of copper accumulation on health status. We herein report the development of a dual target and location-activated rhodamine–spiropyran probe, termed Rhod-SP, activated by the presence of lysosomal Cu2+. Rhod-SP contains a proton recognition unit of spiropyran, which provides molecular switching capability, and a latent rhodamine fluorophore for signal transduction. Upon activation by lysosomal acidic pH, Rhod-SP binds with Cu2+ by spiropyran-based proton activation, promoting, in turn, rhodamine ring opening, which shows a “switched on” fluorescence signal. However, to protect Rhod-SP from degradation and interference by the physiological environment, it is engineered on mesoporous silica nanoparticles (MSNs), and the surface of Rhod-SP@MSNs is further anchored with β-cyclodextrin (β-CD) to enhance the solubility and bioavailability of Rhod-SP@MSN-CD. Next, to enhance cell specificity, a guiding unit of c(RGDyK) peptide conjugated adamantane (Ad-RGD) as prototypical system, is incorporated on the surface of Rhod-SP@MSN-CD to target integrin αvβ3 and αvβ5 overexpressed on cancer cells. Fluorescence imaging showed that both Rhod-SP@MSN-CD and Rhod-SP@MSN-CD-RGD were suitable for visualizing exogenous and endogenous Cu2+ in lysosomes of living cells. This strategy addresses some common challenges of chemical probes in biosensing, such as spatial resolution in cell imaging, the solubility and stability in biological system, and the interference from intracellular species. The newly designed nanoprobe, which allows one to track, on a location-specific basis, and visualize lysosomal Cu2+, offers a potentially rich opportunity to examine copper physiology in both healthy and diseased states.

DNA self-assembled nanomaterials contain several properties of both DNA and nanomaterials. Compared with DNA–nanomaterial complexes, DNA self-assembled nanomaterials more closely resemble living beings, and therefore they have lower cytotoxicity at high concentrations. Functional DNA self-assemblies also have high density of DNA for multivalent reaction and three-dimensional nanostructures for cell uptake. Now and in the future, we envision the use of DNA bases in making designer molecules for many challenging applications confronting chemists. With the further development of artificial DNA bases using smart organic synthesis, DNA macromolecules based on elegant molecular assembly approaches are expected to achieve great diversity, additional versatility, and advanced functions.

Increasing the rate of target binding on the surface and enhancing the fluorescence signal restoration efficiency are critical to the desirable biomedical application of carbon nanomaterials, for example, single-walled carbon nanotubes (SWNTs). We describe here a strategy to increase the target binding rate and enhance the fluorescence signal restoration efficiency on the DNA-functionalized SWNT surface using a short complementary DNA (scDNA) strand. The scDNA causes up to a 2.5-fold increase in association rate and 4-fold increase in fluorescence signal restoration by its competitive assembly on the nanostructure’s surface and inducing a conformational change that extends the DNA away from the surface, making it more available to bind target nucleic acids. The scDNA-induced enhancement of binding kinetics and fluorescence signal restoration efficiency is a general phenomenon that occurred with all sequences and surfaces investigated. Through this competitive assembly strategy of scDNA, performance improvement of the carbon-nanomaterial-based biosensing platform for both in vitro detection and live cell imaging can be reached.Keywords: biosensors; carbon nanomaterials; competitive assembly; interface; short complementary DNA

In this paper, we proposed a facile and accurate way for controlling multiplex fluorescent logic gates through changing the exciting and the observing wavelengths. As proof-of-principle, a Pb2+-specific DNAzyme probe and a thymine (T)-rich DNA probe were introduced to a double-stranded (ds-) DNA. The addition style of the two ions served as the four inputs by changing the distance of the three fluorophores, 6-carboxyfluorescein (FAM), ALEXA 532 (ALEXA) and carboxytetramethylrhodamine (TAMRA), all of which were modified on the dsDNA probe. Compared with the previous methods, the present approach needed neither different inputs nor the change of sequence of the probe to achieve multiplex logic gates. Furthermore, the modularity of the strategy may allow it to be extended to other types of logic gates.

In this work, we propose a method for constructing silver nanoparticles (AgNPs) on mesoporous silica nanospheres (MSNs) by a DNA-templated process. By in situ formation, the gatekeeper can be easily modulated to meet different degrees of glutathione (GSH) stimuli for location-specific drug release.