A novel Z-scheme heterostructure photocatalyst, CoFeN-g-C3N4 (CFN-CN), was prepared by a simple strategy, and its heterostructure and a photo-Fenton system were used to synergistically catalyze the ...degradation of azo dyes. The experimental results showed that the CFN-CN1 heterojunction exhibited superior photocatalytic degradation performance, and the degradation rate of Methyl Orange (MO) reached 96.8% in 40 min. The degradation rate constants were 11.8 and 2.81 times those of CN and CFN, respectively. CFN-CN1 also shows excellent catalytic degradation performance for other azo dyes (Congo Red (CR), Acid Orange 7 (AO7), Mordant Black 17 (MB17) and Acid Red B (ARB)), and the degradation efficiencies all exceeded 90%. Furthermore, the addition of inorganic anions (Cl−, HCO3− and SO42−) affects the degradation of azo dyes, especially HCO3− which significantly promotes the degradation of MO. The radical trapping experiments and EPR results indicated that superoxide radicals (·O2−) and hydroxyl radicals (·OH) were the main active species. The above research reveals that the CFN-CN heterojunction synergistic photo-Fenton system may provide new hints for the degradation and removal of azo dyes from wastewater.
Bioreactors with environment responsiveness for smart detection has attracted widespread interest. Bioreactors that operate in liquid have excellent reaction speed and sensitivity, and those that ...operate at a solid interface have unique portability and stability. However, bioreactors that can simultaneously take advantage of both properties are still limited. Here, we developed a metal-organic framework (MOF) integrated hydrogel bioreactor that can accommodate both solid and liquid properties by using a hydrogel as a quasi-liquid medium. To enhance the stability and intelligence of the hydrogel bioreactor, we have opted for the utilization of europium metal-organic framework (Eu-MOF) as the optical output to withstand long-term storage challenges, and DNA as the highly programmable substance for intelligent target response. On this basis, smart detection of metal ions and biological micro-molecules have been achieved. Notably, this quasi-liquid hydrogel bioreactor has effectively tackled the intrinsic issues of inadequate dispersion stability of Eu-MOF in liquid systems and poor stability of DNA against environmental interference. Moreover, this MOF integrated hydrogel bioreactor has been applied to the construction of a portable hydrogel bioreactor, which enables platform-free and arrayed target detection via a smartphone, providing a new perspective for further promoting the application of quasi-liquid hydrogel bioreactors and intelligent nanobiological sensors.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Balancing operability and performance has long been a focus of research in bioanalysis and biosensing. In this work, between the traditional wet chemistry and dry chemistry, we develop a semi-dry ...smart biosensing platform with favourable operability and performance for metal ions detection. This platform is based on the integration of a stimuli-responsive hydrogel with intelligent image recognition. The hydrogel consists of agarose as a matrix and well-designed fluorescent DNA probes as response elements. Target metal ions in a test sample can diffuse into the hydrogel and activate the DNA probes, outputting fluorescence signals for intelligent imaging. In this way, sensitive and convenient detection of metal ions such as potassium ions (K
+
) and mercury ions (Hg
2+
) can be achieved without the assistance of huge instruments and professional workers. The detection limits for K
+
and Hg
2+
are 0.34 mM and 5.6 nM, respectively. Detection of ions in serum and lake water is also available. Moreover, the hydrogel-based biosensing platform exhibits favorable selectivity, anti-degradation ability, and long-term stability. High-throughput testing can be also achieved by punching multiple test microwells in a single piece of hydrogel. The concept and successful practice of a semi-dry chemistry-based strategy make up for the shortcomings of wet chemistry and dry chemistry, and provide a promising approach for on-site testing.
A semi-dry chemistry-based biosensing platform was developed for detection of metal ions by intelligent stimulus-responsive DNA hydrogel. The platform combines the advantages of liquid (wet) chemistry and solid (dry) chemistry, providing a promising approach for on-site testing.
In this work, we succeeded in establishing a new method for proteins and small molecules analysis based on the small molecule-linked DNA and nucleic acid hyperbranched rolling circle amplification ...(HRCA). Small molecule linked DNA by chemical modification was used as a flexible tool to study protein-small molecule interactions. The HRCA reaction which would produce signal amplification was regulated by the steric effect depending on whether the target proteins were present. In the implement of the proposed strategy, streptavidin (SA)-biotin and anti-digoxin antibody (anti-Dig)-digoxin were chosen as two model partners. Experimental results showed that the quantitative detection of SA and anti-Dig was realized both with nanomolar detection limits. The small molecules biotin and digoxin were also detected at nanomolar levels in a wide range of 1nM~100µM and 1nM~10µM, respectively. Meanwhile, the results indicated that the method had a favorable specificity in analyzing proteins or small molecules. Thus, it may be expected to quantitatively analyze some protein markers and small molecular drugs in complex biological samples.
•A flexible strategy for the analysis of proteins and small molecules is developed.•Small molecules-linked DNA on the second base is first used for biosensing.•Sterically tunable signal amplification is developed for targets detection.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Schematic illustration of the piezo-catalytic for the degradation behavior under simulated visible light and ultrasonic activation.
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•Ag dots-modified BaTiO3 catalysts with different ...silver content were successfully prepared.•Ag/BaTiO3 presented good piezo-photocatalytic activity in degrading Rhodamine B under light irradiation and ultrasonic vibration.•The piezo-photocatalytic efficiency of Ag/BaTiO3 was further improved under O2 atmosphere.
Piezoelectric nanomaterials have attracted much attention due to their ability to modulate photo-excited carrier separation and migration under strain. Perovskite-structured BaTiO3 (BT) is a promising piezo-photocatalytic material due to its high piezoelectric coefficient and special phase structure. In this work, a series of x wt.% Ag/BT composites prepared by a two-step approach were developed for piezo-photocatalysis applications. The 0.8 wt.% Ag/BT showed an excellent piezo-photocatalytic performance for degrading 75.8 % Rhodamine B (RhB) in 60 min. Especially, the catalytic performances were strongly correlated with the atmosphere conditions of the catalyst. The piezo-photodegradation rate of RhB by 0.8 wt.% Ag/BT under O2 atmosphere reached 95.7 % in 40 min, and the first order kinetic rate constant (k) reached 0.06759 min−1, which was 9.9 and 2.4 times that of N2 and air condition, respectively. The Density functional theory (DFT) calculations further revealed that dissolved oxygen could enhance the material's adsorption of RhB. Compared with hydroxyl free radicals (OH) and holes (h+), superoxide radicals (O2–) play an indispensable role in the catalytic process through the trapping experiments and ESR analyses. Furthermore, the RhB degradation pathway and potential ecotoxicity were also proposed. This work is hoped to provide an understanding the mechanism of piezo-photocatalysis and bring new ideas for the development of piezo-photocatalysis catalysis for multifunctional environmental applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Electrochemical biosensing relies on electron transport on the electrode surface. However, the limited functional area of the two-dimensional electrode prevents the qualitative breakthrough in the ...efficiency of electron transfer. Here, a three-dimensional electron transporter was constructed to improve the efficiency of electron transfer by using an interface-immobilized DNA hydrogel. A three-dimensional pure DNA hydrogel is constructed and used as a scaffold for electron transfer. Then, an electron mediator is embedded in the DNA hydrogel through intercalative binding, and DNAzyme with intrinsic peroxidase-like activity is introduced at the node of the hydrogel scaffold to fabricate an electrochemical biosensor. The conduction of the electron mediator in the scaffold enables the acquisition of long-distance DNAzyme catalytic signals, thereby overcoming the limitation of two-dimensional electrodes. This three-dimensional electron transporter is significant for enriching the toolbox of electrochemical biosensing and can provide potential support for the development of highly sensitive biosensors.
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IJS, KILJ, NUK, PNG, UL, UM
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Electrocatalytic CO2 reduction (ECR) into valuable chemicals, especially driven by renewable energy, presents a promising pattern to realize carbon neutrality. Site-isolated metal ...complexes flourish in the area of ECR as single-atom-like catalysts because of their competent and tailorable activity. In this study, salophen-based metal (Fe, Co, Ni and Cu) complexes were anchored onto carbon nanotubes (CNTs) to construct efficient catalysts for electrochemically converting CO2 to CO. Both experimental and theoretical results verified that CO2 activation was the rate-determining step for the catalytic performance of these hybrid molecular catalysts. The coordinate activation ability can be manipulated by varying the metal centers. The as-synthesized Fe-salophen hybrid CNT (Fe-salophen/CNT) shows the best activity and selectivity of −13.24 mA·cm−2 current density with 86.8% Faradaic efficiency for generating CO (FECO) at −0.76 V vs. RHE in aqueous solution, whereas Cu-salophen/CNT only achieved a −2.22 mA·cm−2 current density and 57.9% FECO under the same reaction conditions. These distinct catalytic performances resulted from the different coordination activation abilities of CO2 on various metal centers.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
MicroRNAs (miRNAs) are important biomacromolecules used as biomarkers for the diagnosis of several diseases. However, current detection strategies are limited by expensive equipment and complicated ...procedures. Here, we develop a portable, sensitive, and stable (Eu-MOF)-based sensing platform to detect miRNA via smartphone. The Eu-MOF absorbs the carboxyfluorescein (FAM)-tagged probe DNA (pDNA) to generate hybrid pDNA@Eu-MOF, which can efficiently quench the fluorescence of FAM through a photoinduced electron transfer (PET) process. When integrated with a smartphone, the nonemissive pDNA@ Eu-MOF hybrid could be utilized as a portable and sensitive platform to sense miRNA (miR-892b) with a detection limit of 0.32 pM, which could be even distinguished by the naked eye. Moreover, this system demonstrates high selectivity for identifying miRNA family members with single-base mismatches. Furthermore, the expression levels of miRNA in cancer cell samples could be analyzed accurately. Therefore, the proposed method offers a promising guideline for the design of MOF-based sensing strategies and expands their potential applications for diagnostic purposes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A novel Z-scheme heterostructure photocatalyst, CoFeN-g-C 3 N 4 (CFN-CN), was prepared by a simple strategy, and its heterostructure and a photo-Fenton system were used to synergistically catalyze ...the degradation of azo dyes. The experimental results showed that the CFN-CN1 heterojunction exhibited superior photocatalytic degradation performance, and the degradation rate of Methyl Orange (MO) reached 96.8% in 40 min. The degradation rate constants were 11.8 and 2.81 times those of CN and CFN, respectively. CFN-CN1 also shows excellent catalytic degradation performance for other azo dyes (Congo Red (CR), Acid Orange 7 (AO7), Mordant Black 17 (MB17) and Acid Red B (ARB)), and the degradation efficiencies all exceeded 90%. Furthermore, the addition of inorganic anions (Cl − , HCO 3 − and SO 4 2− ) affects the degradation of azo dyes, especially HCO 3 − which significantly promotes the degradation of MO. The radical trapping experiments and EPR results indicated that superoxide radicals (˙O 2 − ) and hydroxyl radicals (˙OH) were the main active species. The above research reveals that the CFN-CN heterojunction synergistic photo-Fenton system may provide new hints for the degradation and removal of azo dyes from wastewater.
A novel Z-scheme heterostructure photocatalyst, CoFeN-g-C
3
N
4
(CFN-CN), was prepared by a simple strategy, and its heterostructure and a photo-Fenton system were used to synergistically catalyze ...the degradation of azo dyes. The experimental results showed that the CFN-CN1 heterojunction exhibited superior photocatalytic degradation performance, and the degradation rate of Methyl Orange (MO) reached 96.8% in 40 min. The degradation rate constants were 11.8 and 2.81 times those of CN and CFN, respectively. CFN-CN1 also shows excellent catalytic degradation performance for other azo dyes (Congo Red (CR), Acid Orange 7 (AO7), Mordant Black 17 (MB17) and Acid Red B (ARB)), and the degradation efficiencies all exceeded 90%. Furthermore, the addition of inorganic anions (Cl
−
, HCO
3
−
and SO
4
2−
) affects the degradation of azo dyes, especially HCO
3
−
which significantly promotes the degradation of MO. The radical trapping experiments and EPR results indicated that superoxide radicals (&z.rad;O
2
−
) and hydroxyl radicals (&z.rad;OH) were the main active species. The above research reveals that the CFN-CN heterojunction synergistic photo-Fenton system may provide new hints for the degradation and removal of azo dyes from wastewater.
A schematic illustration of the photo-Fenton degradation of azo dyes by a Z-scheme CFN-CN1 heterojunction under visible light irradiation.
