Facile Fabrication of Highly Efficient g‑C₃N₄/Ag₂O Heterostructured Photocatalysts with Enhanced Visible-Light Photocatalytic Activity

Highly efficient visible-light-driven g-C₃N₄/Ag₂O heterostructured photocatalysts were prepared by a simple liquid phase synthesis method at room temperature. The composition, structure, morphology, and optical absorption properties of the as-prepared g-C₃N₄/Ag₂O composites were characterized by XRD, FTIR, XPS, TEM, and UV–vis DRS, respectively. We found interestingly that the photogenerated charge carriers separations of the as-prepared g-C₃N₄/Ag₂O composites were closely related to the mass ratio of g-C₃N₄ and Ag₂O. When the mass ratio of g-C₃N₄ and Ag₂O reached 1:4, the as-prepared composite exhibited the highest photocatalytic activity, which was almost 11 and 1.2 times as high as that of individual g-C₃N₄ and Ag₂O, respectively. The enhancement of photocatalytic activity could be attributed to the synergetic effects between g-C₃N₄ and Ag₂O as well as the improved dispersibility and the decreased particle size of Ag₂O. Moreover, the as-prepared composites showed excellent stability toward the photodegradation of methyl orange (MO). Finally, a possible photocatalytic and charge separation mechanism was proposed

Enhancement of the Carbon Dots/K₂S₂O₈ Chemiluminescence System Induced by Triethylamine

Triethylamine (TEA), a common coreactant for electrochemiluminescence (ECL), is first utilized as a coreactant for chemiluminescence (CL). The CL intensity of carbon dots/K₂S₂O₈ could be increased by ∼20 times in the presence of TEA. On the basis of this fascinating phenomenon, a room temperature operated senor is constructed for the fast, selective, and sensitive determination of TEA. A wide linear relationship between CL intensity and TEA concentration from 1 μM to 1000 μM (<i>R</i>² = 0.9995) was found with the detection limit down to 1 μM. The enhancement mechanism of TEA to this CL system is carefully investigated. Experimental results reveal that the forming of TEA free radical is what indeed induced the enhancement of the CL efficiency of CDs

Figure 5

<p>Design of the second generation aptamer III through the grafting strategy.</p

Exploiting Polydopamine Nanospheres to DNA Computing: A Simple, Enzyme-Free and G‑Quadruplex-Free DNA Parity Generator/Checker for Error Detection during Data Transmission

Molecular logic devices with various functions play an indispensable role in molecular data transmission/processing. However, during any kinds of data transmission, a constant and unavoidable circumstance is the appearance of bit errors, which have serious effects on the regular logic computation. Fortunately, these errors can be detected via plugging a parity generator (pG) at the transmitting terminal and a parity checker (pC) at the receiving terminal. Herein, taking advantage of the efficient adsorption/quenching ability of polydopamine nanospheres toward fluorophore-labeled single-stranded DNA, we explored this biocompatible nanomaterial to DNA logic computation and constructed the first simple, enzyme-free, and G-quadruplex-free DNA pG/pC for error detection through data transmission. Besides, graphene oxide (GO) was innovatively introduced as the “corrective element” to perform the output-correction function of pC. All the erroneous outputs were corrected to normal conditions completely, ensuring the regular operation of later logic computing. The total operation of this non-G4 pG/pC system (error checking/output-correction) could be completed within 1 h (about ¹/₃ of previous G4 platform) in a simpler and more efficient way. Notably, the odd pG/pC with analogous functions was also achieved through negative logic conversion to the fabricated even one. Furthermore, the same system could also perform three-input concatenated logic computation (XOR-INHIBIT), enriching the complexity of PDs-based logic computation

Comparison between the DNAzyme functions of the aptamers 1 and I.

<p>(A) UV−Vis absorption spectra (after 4 min) for analyzing 0.5 µM catalysts with the ABTS−H₂O₂ colorimetry in the detection buffer: a) hemin, b) hemin plus the aptamer 1, c) hemin plus the aptamer I, d) hemin plus a control DNA obtained by replacing the G residues of two spacers in the aptamer I with T. (B) Reaction kinetics of the H₂O₂-mediated ABTS oxidation catalyzed by: 1) the hemin−I DNAzyme, 2) the hemin−1 DNAzyme.</p

Pd Nanowires as New Biosensing Materials for Magnified Fluorescent Detection of Nucleic Acid

The designed synthesis of new nanomaterials with controlled shape, composition, and structure is critical for tuning their physical and chemical properties, and further developing interesting analytical sensing devices. Herein, we presented that Pd nanowires (NWs) can be used as a new biosensing platform for high-sensitivity nucleic acid detection. The general sensing concept is based on the fact that Pd NWs can adsorb the fluorescently labeled single-stranded DNA probe and lead to substantial fluorescence quenching of dye, followed by specific hybridization with the complementary region of the target DNA sequence. This results in desorption of double-stranded DNA from Pd NWs surface and subsequent recovery of fluorescence. Furthermore, an amplification strategy based on Pd NWs for nucleic acid detection by using exonuclease III (Exo III) was demonstrated. The present dual-magnification sensing system combined Pd NWs with Exo III has a detection range of 1.0 nM to 2.0 μM with the detection limit of 0.3 nM (S/N = 3), which is about 20-fold higher than that of traditional unamplified homogeneous assays

UV−Vis absorption spectra (after 4 min) for analyzing the DNAzyme functions of different G-quadruplex aptamers: a) 1 µm hemin, b) a plus 1 µm of the aptamer 2, c) a plus 1 µm of the aptamer II, d) a plus 1 µm of the aptamer 3.

<p>The inset shows the reaction kinetics corresponding to the aptamer 2 (b) and the aptamer II (c).</p

A Facile One-Pot Method to Synthesize a Polypyrrole/Hemin Nanocomposite and Its Application in Biosensor, Dye Removal, and Photothermal Therapy

In this work, we introduced a facile method for the construction of a polypyrrole/hemin (PPy/hemin) nanocomposite via one-pot chemical oxidative polymerization. In this process, a hemin molecule serving as a dopant was entrapped in the PPy nanocomposite during chemical oxidative polymerization. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and UV–visible spectroscopy results demonstrated that the PPy/hemin nanocomposite was successfully synthesized. The as-prepared nanocomposite exhibited intrinsic peroxidase-like catalytic activities, strong adsorption properties, and an excellent near-infrared (NIR) light-induced thermal effect. We utilized the nanomaterials to catalyze the oxidation of a peroxidase substrate 3,3,5,5-tetramethylbenzidine by H₂O₂ to the oxidized colored product which provided a colorimetric detection of glucose. As low as 50 μM glucose could be detected with a linear range from 0.05 to 8 mM. Moreover, the obtained nanocomposite also showed excellent removal efficiency for methyl orange and rhodamine B and a photothermal effect, which implied a promising application as the pollutant adsorbent and photothermal agent. The unique nature of the PPy/hemin nanocomposite makes it very promising for the fabrication of inexpensive, high-performance bioelectronic devices in the future

Facial Synthesis of PtM (M = Fe, Co, Cu, Ni) Bimetallic Alloy Nanosponges and Their Enhanced Catalysis for Oxygen Reduction Reaction

Constructing electrocatalysts with enhanced activity and stability is necessary due to the increasing demands of the fuel cell industry. This work demonstrates a facile approach to synthesize well-defined three-dimensional (3D) PtM (M = Fe, Co, Cu, Ni) bimetallic alloy nanosponges (BANs) in the presence of Al. Significantly, with the aid of Al, the as-prepared BANs exhibit greatly enhanced electrochemistry catalytic activity in an oxygen reduction reaction (ORR), and PtFe BANs appear the best ORR property among the four BANs and commercial Pt/C catalysts. This work may provide a universal approach for convenient and large-scale fabrication of porous bimetallic nanocatalysts, thus providing promising potential application as an efficient cathodic component in fuel cells for industrial production

Schematic of the grafting strategy for aptamer design.

<p>The DNA duplex containing Watson-Crick base pairs of the first generation aptamer 3 is grafted onto the G-quadruplex structures of 1 and 2 to produce two new quadruplex/duplex DNA structures I and II as the second generation aptamers.</p