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Nanothermometry explores the use of temperature‐dependent properties of materials for remote and sensitive thermal readout at the nanoscale. The currently established nanothermometers are largely limited by uncontrollable nanoparticle flocculation, complex experimental setup, and narrow working temperature range. Here it is shown that gold nanoparticles (e.g., spheres, rods) embedded in a hydrogel can afford sensitive, durable, and range‐tunable temperature sensing via the terminal breathing of the nanoparticle surface‐grafted DNA. The realization of the plasmonic hydrogel thermometer with a thermal sensitivity of ≤2 °C relies on the dynamically modulable interparticle spacing by thermo‐responsive terminal base pairing/unpairing of the surface DNA. By altering the alcoholic ratio of the hydrogel, the temperature‐response range can be continuously regulated based on solvent‐mediated DNA base pairing. Compared with the colloidal counterpart, importantly, the hydrogel thermometer exhibits greatly improved thermal sensing capability (e.g., repeatability ≥50 times) while possessing excellent durability. Given the excellent durability, high sensitivity, and programmable temperature response range, the thermometers actuated by DNA breathing for advanced uses in human sensing and optoelectronics are within reach. [ABSTRACT FROM AUTHOR]

The currently established DNA nanoprobes for the detection of mycotoxin from beverages have been limited by complicated sample pretreatment and uncontrollable nanoparticle flocculation in complex systems. We develop a rapid colorimetric approach for ochratoxin A (OTA) detection in Baijiu in a sample-in/"yes" or "no" answer-out fashion through target-modulated base pair stacking assembly of DNA-functionalized gold nanoparticles (DNA–AuNPs). The colorimetric signification of OTA relies on the competition of OTA with the AuNP surface-grafted DNA in binding with an OTA-targeted aptamer. The specific recognition of OTA by the aptamer prevents DNA duplex formation on the AuNP surface, thereby inhibiting the base pair stacking assembly of the DNA–AuNPs and giving rise to a "turn-on" color. By further suppressing DNA hybridization using a bulged loop design and an alcohol solution, the DNA–AuNPs exhibit an improved reproducibility for OTA sensing while maintaining excellent susceptivity to OTA. A detection limit of 88 nM was achieved along with high specificity towards OTA, which is lower than the maximum tolerated level of OTA in foodstuffs defined by countries worldwide. The entire reaction time, avoiding sample pretreatment, is less than 17 min. The DNA–AuNPs with anti-interference features and sensitive "turn-on" performance promise convenient on-site detection of mycotoxin from daily beverages. [ABSTRACT FROM AUTHOR]

Self-assembly performed in ionic liquids (ILs) as a unique solvent promises distinct functions and applications in sensors, therapeutics, and optoelectronic devices due to the rich interactions between nanoparticle building blocks and ILs. However, the general consideration that common nanoparticles are readily destabilized by counterions in an IL has largely prevented researchers from investigating controlled nanoparticle assembly in IL-based systems. This study explores the assembling behaviour of double-stranded (ds) DNA-functionalized gold nanoparticles (dsDNA–AuNPs) in hydrated ionic liquids. The DNA base pair stacking assembly of dsDNA–AuNPs occurs at a low IL concentration (<5%). However, a moderate ionic liquid concentration (5–40%) can de-hybridize dsDNA and leaves single-stranded (ss) DNA stabilizing the AuNPs. In concentrated ionic liquids (>40%), interestingly, the higher ionic strength leads to the assembly of DNA–AuNPs. The triphasic assembly trend is also generally observed regardless of the type of IL. By down-regulation of DNA's melting temperature with the IL, the assembly of DNA–AuNPs affords robust response to a lower temperature range, promising applications in plasmonic devices and range-tunable temperature sensors. [ABSTRACT FROM AUTHOR]

In this work, we have synthesized gold nanoparticles (AuNPs) using flavonoids of Scutellaria barbata as reducing and stabilizing agent. The prepared AuNPs were studied by using various spectroscopic and microscopic techniques. TEM analysis showed the formation of 20 nm sized spherical nanoparticles. XRD analysis confirmed the formation of crystalline face centred cubic structured particles. Further, we studied the as prepared AuNPs for their efficiency to act as a novel class of amyloid-β (Aβ) inhibitors. The results showed that several small and relatively amorphous aggregates validated the exceptional efficiency of AuNPs in inhibiting Aβ40 aggregation. Therefore, the prepared AuNPs has future prosperous towards the treatment of Alzheimer's disease. [ABSTRACT FROM AUTHOR]

Abstract: Nanoparticle (NP) arrays exhibit collective physical and chemical properties, which are potentially applicable to various nanodevices, such as data storage media and biosensors. In this Communication, a spontaneous method of constructing the 2D NP arrays from precursory 1D chains of DNA‐modified NPs is described. The single‐stranded (ss) DNA‐modified gold NPs are hybridized to a long repetitive ssDNA synthesized with rolling circle amplification to produce the precursory NP chains. Transmission electron microscopy reveals that the chains of fully matched double‐stranded (ds) DNA‐modified NPs undergo shrinkage and folding during evaporation to afford the 2D NP arrays. In particular, the chains of long dsDNA‐modified NPs with short interparticle spacing form the NP arrays with anisotropic interparticle spacing. The present approach could be useful for readily aligning NPs on the substrate surface. [ABSTRACT FROM AUTHOR]

Due to the potential of gold nanoparticle (AuNP)-based trace analysis, the discrimination of small AuNP clusters with different assembling stoichiometry is a subject of fundamental and technological importance. Here we prepare oligomerized AuNPs with controlled stoichiometry through DNA-directed assembly, and demonstrate that AuNP monomers, dimers and trimers can be clearly distinguished using dark field microscopy (DFM). The scattering intensity for of AuNP structures with stoichiometry ranging from 1 to 3 agrees well with our theoretical calculations. This study demonstrates the potential of utilizing the DFM approach in ultra-sensitive detection as well as the use of DNA-directed assembly for plasmonic nano-architectures. [ABSTRACT FROM AUTHOR]

A systematic and comprehensive survey on the preparation and functionalization approaches for a wide range of gold nanostructures that exhibit surface plasmon resonance (SPR) in the near-infrared (NIR) region is presented. This review is focused on the efficient synthetic strategies for precise control of gold nanostructures with NIR plasmonic resonance, and effects of size, shapes and composition on their optical absorption properties. Possible mechanisms on controllable synthesis of various gold nanostructures are discussed. Additionally, the surface functionalization of gold nanostructures is summarized. This review provides suggestions for guiding controllable synthesis of monodisperse, multifunctional plasmonic gold nanostructures in a simple and effective way. [ABSTRACT FROM AUTHOR]

Abstract: Involvement of single‐nucleotide polymorphism (SNP) genotyping in healthcare should allow for more effective use of pharmacogenomics. However, user‐friendly assays without the requirement of a special instrument still remain unavailable. This study describes naked‐eye SNP discrimination in exon 5 of the human cytochrome P450 2C19 monooxygenase gene, CYP2C19*1 (the wild‐type allele) and CYP2C19*2 (the variant allele with G681A point mutation). The present assay is composed of allele‐specific single‐base primer extension and salt‐induced aggregation of DNA‐modified gold nanoparticles (DNA–AuNPs). Genetic samples extracted from human hair roots are subjected to this assay. The results are verified by direct sequencing. This study should promise the prospective use of DNA–AuNPs in gene diagnosis. [ABSTRACT FROM AUTHOR]

We communicate an unconventional synthesis of Au nanoplates with high yield and excellent reproducibility through polyvinylpyrrolidone (PVP)-assisted H2O2 reduction. Unlike the ones prepared using halide-based surfactants, the PVP-capped Au nanoplates are found to afford fairly easy bio-functionalization, suggesting a vastly expanded spectrum of applications in bio-related fields. [ABSTRACT FROM AUTHOR]

Gold nanoparticles modified with DNA duplexes are rapidly and spontaneously aggregated at high ionic strength. In contrast, this aggregation is greatly suppressed when the DNA duplex has a single-base mismatch or a single-nucleotide overhang located at the outermost surface of the particle. These colloidal features emerge irrespective of the size and composition of the particle core; however, the effects of the shape remain unexplored. Using gold nanorods and nanotriangles (nanoplatelets), we show herein that both remarkable rapidity in colloidal aggregation and extreme susceptibility to DNA structural perturbations are preserved, regardless of the shape and aspect ratio of the core. It is also demonstrated that the DNA-modified gold nanorods and nanotriangles are applicable to naked-eye detection of a single-base difference in a gene model. The current study corroborates the generality of the unique colloidal properties of DNA-functionalized nanoparticles, and thus enhances the feasibility of their practical use. [ABSTRACT FROM AUTHOR]

Although progress has been made in the construction of single-electron devices (SEDs), few of the reported approaches have proved practically applicable, mainly owing to their cost-ineffectiveness and need for sophisticated instrumentation. Herein, a conceptually new method for fabricating SEDs through the metallization of divalent DNA-nanoparticle conjugates is described. Specifically, divalent DNA copolymers that are conjugated to gold nanoparticles (AuNP) were synthesized by application of the enzymatic extension of DNA conjugated on quantum-sized AuNPs. This conjugate structure allows the distance between the resulting poly(dG)-poly(dC) and the AuNP to be controlled by an ssDNA spacer. To afford poly(dG)-poly(dC) sequence-specific metal deposition, Cisplatin capable of specific chemisorption on the poly(dG)-poly(dC) is incubated with the divalent DNA copolymer-AuNP conjugates, followed by reduction of the Cisplatin to Pt metal at base resolution. As a result, AuNPs separated from the Pt 'electrodes' by the ssDNA barriers in a single conjugate could be created as a double-tunnel junction for SEDs. This study is thought to be an important step toward the programmable organization of DNA for use in SEDs. [ABSTRACT FROM AUTHOR]

The contamination of heavy metals (e.g., Hg, Pb, Cd and As) poses great risks to the environment and human health. Rapid and simple detection of heavy metals of considerable toxicity in low concentration levels is an important task in biological and environmental analysis. Among the many convenient detection methods for heavy metals, DNA-inspired gold nanoparticles (DNA-AuNPs) have become a well-established approach, in which assembly/disassembly of AuNPs is used for colorimetric signaling of the recognition event between DNA and target heavy metals at the AuNP interface. This review focuses on the recent efforts of employing DNA to manipulate the interfacial properties of AuNPs, as well as the major advances in the colorimetric detection of heavy metals. Beginning with the introduction of the fundamental aspects of DNA and AuNPs, three main strategies of constructing DNA-AuNPs with DNA binding-responsive interface are discussed, namely, crosslinking, electrostatic interaction and base pair stacking. Then, recent achievements in colorimetric biosensing of heavy metals based on manipulation of the interface of DNA-AuNPs are surveyed and compared. Finally, perspectives on challenges and opportunities for future research in this field are provided. [ABSTRACT FROM AUTHOR]