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Design of highly active and stable non-precious electrocatalysts towards hydrogen evolution reaction (HER) is a hot research topic in low cost, clean and sustainable hydrogen energy field, yet remaining the important challenge caused by the sluggish reaction kinetics for water-alkali electrolyzers. Herein, a robust electrocatalyst is proposed by designing a novel sub-nanometer of copper and ruthenium bimetallic phosphide nanoclusters (RuxCuyP2) supported on a graphited carbon nanofibers (CNF). Uniform RuxCuyP2 (~1.90 nm) on the surface of CNF are obtained by introducing the dispersed Ru, thereby improving the intrinsic activity for HER. On optimizing the Ru ratio, the (x = y = 1) RuCuP2/CNF catalyst exhibits an excellent HER electroactivity with an overpotential of 10 mV in 1.0 M NaOH electrolyte to produce 10 mA cm−2 current density, which is lower than commercial 20% Pt/C in alkaline solution. Moreover, the kinetic study demonstrated that electrochemical activation energies for HER of RuCuP2/CNF is 20.7 kJ mol−1 highest among different ratio bimetallic phosphide. This simple, cost-effective, and environmentally friendly methodology can pave the way for exploitation of bimetallic phosphide nanoclusters for catalyst design.

The rapid and accurate bacterial testing is a critical step for the management of infectious diseases, but challenges remain largely due to a lack of advanced sensing tools. Here we report the development of highly plasmon-active, biofunctional nanoparticle arrays for simultaneous capture, identification, and differentiation of bacteria by surface-enhanced Raman scattering (SERS). The nanoarrays were facilely prepared through an electrostatic mechanism-controlled self-assembly of metallic nanoparticles at liquid-liquid interfaces, and exhibited high SERS sensitivity beyond femtomole, good reproducibility (relative standard deviation of 2.7%) and stability. Modification of the nanoarrays with concanavalin A allowed to effective capture of both Gram-positive and Gram-negative bacteria (bacterial-capture efficiency maintained beyond 50%) at bacterial concentrations ranging from 50 to 2000 CFU mL−1, as determined by the plate-counting method. Moreover, single-cell Raman fingerprinting and discrimination of eight different bacteria species with high signal-to-noise ratio, excellent spectral reproducibility, and a total assay time of 1.5 h was achieved under fairly mild conditions (24 μW, acquisition time: 1 s). Collectively, we believe that our biofunctionalized, SERS-based self-assembled nanoarrays have great potential to help in rapid and label-free bacterial diagnosis and phenotyping study.

Rice blast is one of the most destructive disease, which is estimated to cause 10–30% loss of global rice output annually. Single nucleotide change in bsr-d1 promoter (SNP-33 G) is conferred broad-spectrum resistance to rice blast. In this paper, we reported the construction of a relatively simple, inexpensive and ultrasensitive electrochemical DNA biosensor to detect SNP-33 G for the first time. PCR product with a 19-nt-long sticky end was generated in the presence of T4 DNA polymerase and dGTP, which was used as a powerful signal amplifying tool in the assay. The biosensor was immersed in RuHex buffer as a redox, and a high current signal could be observed due to the electrostatically bound between RuHex and the phosphate backbone of PCR product. Under optimal conditions, the electrochemical DNA biosensor exhibited satisfied performance for the determination of mutant-type of bsr-d1 promoter with a linearity ranging from 0.1 fM to 0.1 pM and a relatively low detection limit of 0.1 fM. The proposed biosensor showed excellent selectivity of SNP-33 G compared to that of wild type bsr-d1 promoter at a ratio of 1:10,000. The results provided a novel method for potential applications in variety screen and breeding for rice blast resistance.

A simple, innovative yet cycle amplification-free strategy was developed for highly sensitive fluorescence detection of activity of DNA methyltransferases and inhibitors, in which cDNA-based extension of potato virus X was used. Briefly, a partial hybrid double strand DNA (dsDNA) probe with the sequence of 5′-GATC-3′ was methylated and cleaved into four parts by dam MTase and DpnI. The newborn 5′-termini of the dsDNA complemented to 3′-end of viral cDNA and initiated dsDNA synthesis by DNA polymerase. The dsDNA product of about 6430-bp-long combined with SG and strong green fluorescence could be detected. However, in the absence of dam MTase, methylation/cleavage could not be initiated and viral cDNA was digested by Exonuclease I, and no fluorescence signal was observed. A correlation between the fluorescence intensity and dam MTase activity was obtained in a range from 0.025 to 5 U/mL of dam MTase, and the detection limit was 0.0087 U/mL. The inhibition study indicated that gentamicin and 5-flurouracil could inhibit the dam MTase activity with IC50 values of 2.24 μM and 2.75 μM, respectively. The proposed assay showed the potential as an accessible platform for simple, rapid and sensitive detection of DNA MTase activity and screening its inhibitors.

Transition metallic phosphides (TMPs) have attracted considerable attention for use as efficient and durable electrocatalysts for the hydrogen evolution reaction (HER). However, it is still challenging for TMPs to achieve HER performance similar to that of the state-of-the-art platinum (Pt) catalysts. Herein, we report new amorphous phosphatized ruthenium-iron bimetallic nanoclusters (RuxFeyP-NCs) supported on graphitized carbon nanofibers (CNF), synthesized through a facile two-step method, which combine the merits of several catalyst design strategies. The amorphous structure allows more catalytically active sites to be exposed, and the synergy between Ru and Fe may boost the intrinsic catalytic activity. Moreover, the conductive CNF support facilitates electron transport and firmly immobilizes RuxFeyP-NCs enabling a long-term stability. The resulting RuxFeyP-NCs/CNF with optimal equimolar Ru and Fe (i.e. RuFeP-NCs/CNF) exhibits outstanding Pt-like HER performance, requiring low overpotentials of 65.8 and 16.0 mV to deliver a current density of 10 mA cm−2 in acidic and alkaline solutions, respectively, and showing a long-term stability of 100 h. The density functional theory (DFT) calculations demonstrate that RuFeP-NCs/CNF shows Gibbs free energy of hydrogen adsorption close to that of Pt and much smaller than that of FeP-NCs/CNF and RuxFey-NCs/CNF controls with non-equimolar Ru/Fe, which rationally explains the experimentally observed prominent HER performance of RuFeP-NCs/CNF.

An electrochemiluminescence (ECL) resonance energy transfer system is constructed for 17β-estradiol (E2) detection using α-FeOOH@CdS nanospheres as the ECL-active substrates and Ag NCs as an efficient quencher. CdS QDs loaded onto three-dimensional (3D) urchin-like α-FeOOH nanospheres (α-FeOOH@CdS nanospheres) exhibited excellent ECL responses, which is attributed to dual-amplification of α-FeOOH frameworks. The 3D hierarchical structure of the α-FeOOH nanospheres provided abundant sites for loading ECL-active species, thus significantly improving the ECL performance of substrates; While Fe3+ presented on surface of α-FeOOH nanospheres could be reduced to Fe2+ in negative potentials, after which might activate persulfate in a Fenton-like process, resulting in more sulfate free radicals for more effective ECL responses via electron transfer reactions. Additionally, Ag nanoclusters (Ag NCs) stabilized by single stranded oligonucleotide were introduced as quenching probes for CdS QDs owing to the well-matched donor-acceptor spectrum for efficient energy transfer, which makes them appropriate for detection of E2. The proposed strategy displayed a desirable dynamic range from 0.01 to 10 pg mL−1 with a limit of detection of 0.003 pg mL−1. The proposed strategy based on the ECL-RET strategy offered an ideal way for E2 detection, and also revealed an alternative platform for detection of other small molecules.

The first simple and sensitive method for fluorescent detection of zucchini yellow mosaic virus (ZYMV) was developed in this study. ZYMV cDNA was used as the template for recombinase polymerase amplification. Terminals of one strand of the dsDNA product were joined by T4 DNA ligase. All linear DNA were digested by T5 exonuclease in solution, while single-stranded cyclic DNA (sscDNA) was intact and was used as the template for enzyme-assisted signal amplification (EASA). Probe 1 was designed with FAM and BHQ bound at its 5′- and 3′-ends, respectively, and the recognition sequence of Nb.BbvCⅠ was in the middle. Probe 1 was hybridised with sscDNA and cleaved into two fragments during EASA. The fluorescence signal in the final solution was detected. The target DNA was amplified twice, and the detection limit of our assay was calculated to be 0.01 pg. This method demonstrates satisfactory selectivity and reproducibility and can be used in practical applications. Additionally, we found that linear DNA could be digested completely by T5 exonuclease at room temperature (approximately 22–24 °C) within 5 min.