Facile Estimation of Surface Oxygen Vacancies in Co3O4 Catalysts with a Colorimetric Method.

Oxygen vacancy (Ov) is known to act as an active center of the metal oxide. Quantification of surface Ov is vital for understanding the quantitative structure-activity relationship. Facile quantification characterization of surface Ov is highly desirable but still challenging. In this study, we presented a simple colorimetric method for rapidly quantifying surface Ov. As an example of metal oxide nanoparticles, Co3O4 was used to catalyze the 3,3',5,5'-tetramethylbenzidine (TMB)-H2O2 colorimetric reaction. It was found that the absorbance of the TMB-H2O2 system was dependent on the surface Ov amount in Co3O4. The investigation of the mechanism showed that the Ov-dependent absorbance would be attributed to the activity of surface Ov to easily adsorb and dissociate H2O2 into a hydroxyl radical (•OH). The absorbance signal of the TMB-H2O2 system acted as a probe to estimate the surface Ov. This colorimetric measurement could be completed in less than 20 min. The Ov concentrations obtained by the proposed colorimetric method matched well with those obtained by X-ray photoelectron spectroscopy. This method does not require any complex operation and expensive equipment and can be performed in any ordinary chemical laboratory. So, this colorimetric method is expected to become an alternative approach for quantifying the surface Ov in metal oxide nanoparticles. This method will provide essential insights into the rational design and application of Ov.

Multifunctional Manganese-Nucleotide Laccase-Mimicking Nanozyme for Degradation of Organic Pollutants and Visual Assay of Epinephrine via Smartphone.

As a natural green catalyst, laccase has extensive application in the fields of environmental monitoring and pollutant degradation. However, susceptibility to environmental influences and poor reusability seriously hinder its application. To address these concerns, for the first time, manganese ion replaced copper ion as the active center to coordinate with guanosine monophosphate (GMP) for synthesizing mimic laccase with high catalytic activity. Compared with natural laccase, the laccase-like nanozyme (Mn-GMPNS) demonstrated superior thermal stability, acid-base resistance, salt tolerance, reusability, and substrate universality. Benefiting from the high catalytic activity of Mn-GMPNS, epinephrine, a significant neurotransmitter and hormone associated with numerous diseases, was visually detected within 10 min and a portable assay by smartphone. More encouragingly, Mn-GMPNS can efficiently degrade dye pollutants, achieving a decolorization rate over 70% within 30 min. Thus, the coordination between manganese ion and nucleotide demonstrated the potential in rational design of nanozymes with high catalytic activity, low cost, good stability, and good biocompatibility.

Fluorescent aptasensor mediated with multiple ssDNA for sensitive detection of acetamiprid in vegetables based on magnetic Fe3O4/C-assisted separation.

Acetamiprid (ACE) is a highly effective broad-spectrum insecticide, and its widespread use is potentially harmful to human health and environmental safety. In this study, magnetic Fe3O4/carbon (Fe3O4/C), a derivative of metal-organic framework MIL-101 (Fe), was synthesized by a two-step calcination method. And a fluorescent sensing strategy was developed for the efficient and sensitive detection of ACE using Fe3O4/C and multiple complementary single-stranded DNA (ssDNA). By using aptamer with multiple complementary ssDNA, the immunity of interference of the aptasensor was improved, and the aptasensor showed high selectivity and sensitivity. When ACE was present, the aptamer (Apt) combined with ACE. The complementary strand of Apt (Cs1) combined with two short complementary strands of Cs1, fluorophore 6-carboxyfluorescein-labeled complementary strand (Cs2-FAM) and the other strand Cs3. The three strands formed a double-stranded structure, and fluorescence would not be quenched by Fe3O4/C. In the absence of ACE, Cs2-FAM would be in a single-chain state and would be adsorbed by Fe3O4/C, and the fluorescence of FAM would be quenched by Fe3O4/C via photoelectron transfer. This aptasensor sensitively detected ACE over a linear concentration range of 10-1000 nM with a limit of detection of 3.41 nM. The recoveries of ACE spiked in cabbage and celery samples ranged from 89.49% to 110.76% with high accuracy.

The usage and costs of national drug price-negotiated anticancer medicines in a first-tier city in Northeast China: a study based on health insurance data.

BACKGROUND: The National Drug Price Negotiation (NDPN) policy has entered a normalisation stage, aiming to alleviate, to some extent, the disease-related and economic burdens experienced by cancer patients. This study analysed the use and subsequent burden of anticancer medicines among cancer patients in a first-tier city in northeast China. METHODS: We assessed the usage of 64 negotiated anticancer medicines using the data on the actual drug deployment situation, the frequency of medical insurance claims and actual medication costs. The affordability of these medicines was measured using the catastrophic health expenditure (CHE) incidence and intensity of occurrence. Finally, we used the defined daily doses (DDDs) and defined daily doses cost (DDDc) as indicators to evaluate the actual use of these medicines in the region. RESULTS: During the study period, 63 of the 64 medicines were readily available. From the perspective of drug usage, the frequency of medical insurance claims for negotiated anticancer medicines and medication costs showed an increasing trend from 2018 to 2021. Cancer patients typically sought medical treatment at tertiary hospitals and purchased medicines at community pharmacies. The overall quantity and cost of medications for patients covered by the Urban Employee Basic Medical Insurance (UEBMI) were five times higher than those covered by the Urban and Rural Resident Medical Insurance (URRMI). The frequency of medical insurance claims and medication costs were highest for lung and breast cancer patients. Furthermore, from 2018 to 2021, CHE incidence showed a decreasing trend (2.85-1.60%) under urban patients' payment capability level, but an increasing trend (11.94%-18.42) under rural patients' payment capability level. The average occurrence intensities for urban (0.55-1.26 times) and rural (1.27-1.74 times) patients showed an increasing trend. From the perspective of drug utilisation, the overall DDD of negotiated anticancer medicines showed an increasing trend, while the DDDc exhibited a decreasing trend. CONCLUSION: This study demonstrates that access to drugs for urban cancer patients has improved. However, patients' medical behaviours are affected by some factors such as hospital level and type of medical insurance. In the future, the Chinese Department of Health Insurance Management should further improve its work in promoting the fairness of medical resource distribution and strengthen its supervision of the nation's health insurance funds.

Uncovering Origin of Chirality of Gold Nanoparticles Prepared through the Conventional Citrate Reduction Method.

Chiral nanoparticles are one of the research hotspots in the field of materials science, chemistry, and biology. Understanding and controlling the chirality of nanoparticles is one key step toward their use, but the origin of nanoparticles' chirality and its determinative factor are not well understood. In this work, we studied the chirality of gold nanoparticles (AuNPs) prepared through the conventional citrate reduction method. Unexpectedly, it was found that small AuNPs (∼13 nm) exhibited opposite chirality to the large AuNPs (>30 nm). The origin of the AuNPs chirality was revealed by comparing the crystal structure between small AuNPs and large AuNPs. It was proposed that the lattice orientation of fivefold-twinned AuNPs may be responsible for the intrinsic chirality of AuNPs. This work provides a deep mechanistic understanding of the intrinsic chirality of the AuNPs and will boost the development of the structure-controlled synthesis and application of chiral AuNPs and other chiral nanomaterials. Furthermore, based on the unexpected size effect, chiral AuNP probes were rationally constructed to improve the precision of chiral recognition.

Surface Oxygen Vacancy-Rich Co3O4 Nanowires as an Effective Catalyst of Luminol-H2O2 Chemiluminescence for Sensitive Immunoassay.

Oxygen vacancy is one intrinsic defect in metal oxide materials. Interestingly, we herein found that the surface oxygen vacancy can significantly enhance the catalytic activity of Co3O4 nanowires in the luminol-H2O2 chemiluminescence (CL) reaction. 0.1 ng/mL Co3O4 nanowires containing 51.3% surface oxygen vacancies possessed ca. 2.5-fold catalytic activity of free Co2+ (the best metal ionic catalyst for the luminol-H2O2 CL reaction). The superior catalytic efficiency is attributed to the enhanced adsorption of H2O2 by surface oxygen vacancies, which in turn accelerates the cleavage of O-O bonds and generates •OH radicals. More importantly, the surface oxygen vacancy-rich Co3O4 nanowires retained about 90% catalytic activity after modification with antibodies. The surface oxygen vacancy-rich Co3O4 nanowires were used to label the secondary antibody, and one sandwich-type CL immunoassay of carcinoembryonic antigen was established. The detection limit was 0.3 ng/mL with a linear range of 1-10 ng/mL. This proof-of-concept work proves that surface oxygen vacancy-rich Co3O4 nanowires are suitable for labeling biomolecules in CL bioanalysis and biosensing.

Carbon Vacancy-Enhanced Activity of Fe-N-C Single Atom Catalysts toward Luminol Chemiluminescence in the Absence of H2O2.

The classic luminol-H2O2 chemiluminescence (CL) systems suffer from easy self-decomposition of H2O2 at room temperature, hindering the practical applications of the luminol-H2O2 CL system. In this work, unexpectedly, we found that the carbon vacancy-modified Fe-N-C single atom catalysts (VC-Fe-N-C SACs) can directly trigger a luminol solution to generate strong CL emission in the absence of H2O2. The Fe-based SACs were prepared through the conventional pyrolysis of zeolitic imidazolate frameworks. The massive carbon vacancies were readily introduced into Fe-N-C SACs through a tannic acid-etching process. Carbon vacancy significantly enhanced the catalytic activity of Fe-N-C SACs on the CL reaction of luminol-dissolved oxygen. The VC-Fe-N-C SACs performed a 13.4-fold CL enhancement compared with the classic luminol-Fe2+ system. It was found that the introduction of a carbon vacancy could efficiently promote dissolved oxygen to convert to reactive oxygen species. As a proof of concept, the developed CL system was applied to detect alkaline phosphatase with a linear range of 0.005-1 U/L as well as a detection limit of 0.003 U/L. This work demonstrated that VC-Fe-N-C SAC is a highly efficient CL catalyst that can promote the analytic application of the luminol CL system.

Peroxidase-Mimicking DNAzymes as Receptors for Label-Free Discriminating Heavy Metal Ions by Chemiluminescence Sensor Arrays.

Receptors are crucial to the analytical performance of sensor arrays. Different from the previous receptors in sensor arrays, herein, peroxidase-mimicking DNAzymes were innovatively used as receptors to develop a label-free chemiluminescence sensor array for discriminating various heavy metal ions in complex samples. The peroxidase-mimicking DNAzymes are composed of functional oligonucleotides and hemin, including G-triplex-hemin DNAzyme (G3-DNAzyme), G-quadruplex-hemin DNAzyme (G4-DNAzyme), and the dimer of G-quadruplex-hemin DNAzyme (dG4-DNAzyme). Circular dichroism (CD) spectroscopy demonstrated that different metal ions diversely affect the conformation of G-quadruplex and G-triplex, resulting in a change in the activity of peroxidase-mimicking DNAzyme. Thus, the unique fingerprints formed to easily discriminate seven kinds of heavy metal ions by principal component analysis (PCA) within 20 min. The discrimination of unknown metal ions in tap water further confirmed its ability for discriminating multiple heavy metal ions. Moreover, it will not bring water pollution due to the good biocompatibility of DNA. Therefore, it not only merely offers a label-free, rapid, environment-friendly, and cheap (1.49 $) sensor assay for discriminating metal ions but also comes up with an innovative way for developing sensor arrays.

Ring-Oven-Assisted In Situ Synthesis of Metal-Organic Frameworks on the Lab-On-Paper Device for Chemiluminescence Detection of Nitrite in Whole Blood.

In situ synthesis of metal-organic frameworks (MOFs) on flexible materials for the fabrication of functional platforms and micro-devices is challenging. The time-/precursor-consuming procedure and uncontrollable assembly are stumbling blocks for constructing this platform. Herein, a novel in situ MOF synthesis method on paper substrates by use of the ring-oven-assisted technique was reported. Utilizing the ring-oven's heating and washing function, MOFs can be synthesized in 30 min on the designated position of paper chips with extremely low-volume precursors. The principle of this method was explained by steam condensation deposition. The MOFs' growth procedure was theoretically calculated by crystal sizes and the results conformed to the Christian equation. As different MOFs (Cu-MOF-74, Cu-BTB, Cu-BTC) can be synthesized successfully on paper-based chips, the ring-oven-assisted in situ synthesis method has great generality. Then, the prepared Cu-MOF-74 loading paper-based chip was applied to the chemiluminescence (CL) detection of nitrite (NO2-), based on the catalysis effect of Cu-MOF-74 on the NO2--H2O2 CL system. Also, by the delicate design of the paper-based chip, NO2- can be detected with the detection limit (DL) of 0.5 nM in whole blood samples without sample pretreatment. This work establishes a distinctive method for the in situ synthesis of MOFs and the application of MOFs on paper-based CL chips.

Tetrakis(4-pyridylphenyl)ethylene-based Zinc Metal-Organic Framework with Aggregation-Induced Chemiluminescence Emission on a Paper Platform for Formaldehyde Detection in Breath.

Volatile formaldehyde (FA) in exhaled breath (EB) is considered as a biomarker for lung cancer (LC). On-the-spot selective and sensitive detection of gaseous FA is rather important for LC screening and diagnosis. Herein, a tetrakis(4-pyridylphenyl)ethylene (Py-TPE)-based zinc metal-organic framework (MOF) with excellent aggregation-induced emission (AIE) property was utilized for absorption and selective detection of FA in EB. The porous Zn-Py-TPE served as a gaseous confinement cavity for the adsorption of FA in EB. Interestingly, Zn-Py-TPE was aggregated on paper, and then aggregation-induced chemiluminescence (CL) emission can be triggered by only adding bis(2,4,6-trichlorophenyl)oxalate (TCPO). Though without H2O2, the CL of Zn-Py-TPE-TCPO was enhanced greatly by FA. FA promoted the aggregation of Zn-Py-TPE on paper by forming halogen bonding between FA and Zn-Py-TPE, which contributed to the better selectivity. FA can also stimulate the production of more singlet oxygen (1O2) in the Zn-Py-TPE-TCPO CL system. Hence, FA could be detected via the proposed Zn-Py-TPE-TCPO system with a quantification linear range of 1.0-100.0 ppb and detection limit of 0.3 ppb. This portable, low-cost, and sensitive paper-based platform can achieve trace FA detection in EB and is expected to provide an on-the-spot screening platform for lung cancer.

Logic-Gates of Gas Pressure for Portable, Intelligent and Multiple Analysis of Metal Ions.

DNA logic gates have shown outstanding magic in intelligent biology applications, but it remains challenging to construct a portable, affordable and convenient DNA logic gate. Herein, logic gates of gas pressure were innovatively developed for multiplex analysis of metal ions. Hg2+ and Ag+ were input to interact specifically with the respective mismatched base pairs, which activated DNA extension reaction by polymerase and led to the enrichment of platinum nanoparticles for catalyzing the decomposition of peroxide hydrogen. Thus, the gas pressure obtained from a sealed well was used as output for detecting or identifying metal ions. Hg2+ and Ag+ were sensitively and selectively detected, and the assay of the real samples was also satisfactory. Based on this, DNA logic gates, including YES, NOT, AND, OR, NAND, NOR, INHIBIT, and XOR were successfully established using a portable and hand-held gas pressure meter as detector. So, the interactions between DNA and metal ions were intelligently transferred into the output of gas pressure, which made metal ions to be detected portably and identified intelligently. Given the remarkable merits of simplicity, logic operation, and portable output, the metal ion-driven DNA logic gate of gas pressure provides a promising way for intelligent and portable biosensing.

Dual-Mode Logic Gate for Intelligent and Portable Detection of MicroRNA Based on Gas Pressure and Lateral Flow Assay.

Molecular logic gate provides an intelligent option for simultaneous detection of biomarkers. Herein, a dual-mode DNA logic gate was proposed to portably and intelligently detect multiple microRNAs (miRNAs) by gas pressure biosensing and lateral flow assay (LFA). A platinum-coated gold nanoparticle (Au@PtNP) with catalase-like activity was used as a signal reporter to achieve a dual-signal readout. MiRNAs as the input initiated the cyclic strand displacement reaction (SDR) to enrich a large amount of Au@PtNPs. Thus, miRNA can be visually detected by a lateral flow strip (LFS) using the grayish-brown color of Au@PtNPs as output 1. Furthermore, Au@PtNP-catalyzed decomposition of H2O2 resulted in gas pressure as output 2, which was measured by a digital and handheld gas pressure meter. As a consequence, microRNA 21 (miR-21) was sensitively and reliably detected with the limit of detection (LOD) of 7.2 pM. The selectivity and real sample analysis were both satisfactory. Significantly, two-input and three-input AND logic gates were successfully developed to realize multiple detection of two miRNAs and three miRNAs, which provide a promising way for intelligent multi-input analysis. Predictably, with the advantages of portability, simplicity, and affordability, the dual-mode logic gate based on gas pressure biosensing and LFA offers a new perspective on the field of intelligent and portable biosensing and bioanalysis.

Acid-accelerated hydrolysis of NaBH4: a gas-generation reaction for diverse gas pressure biosensing.

Gas pressure biosensing is a promising portable analysis method. The gas-generation reaction is crucial to its sensitivity, speed, repeatability, and usability. However, very few gas-generation reactions are available for sensitive, safe, and diverse biosensing. Herein, acid-accelerated hydrolysis of sodium borohydride (NaBH4) was explored for the first time to achieve portable and diverse gas pressure biosensing. The slow hydrolysis and hydrogen generation of NaBH4 in alkaline medium is accelerated with increasing acidity, which increased the gas pressure in a small and sealed tube within 10 min. Thus, a label-free bioassay is easily and specifically achieved once analytes can in-situ generate acid to accelerate the hydrolysis rate of NaBH4, such as glucose, acetylcholine (ACh), adenosine triphosphate (ATP) and others. More importantly, analytes without acid generation could be quantitatively and selectively detected by combining target recognition with acid-generated biochemical reactions for enzyme-linked gas pressure biosensing. Inspired by this, aflatoxin B1 (AFB1)-aptamer interaction-triggered strand displacement reaction was combined with glucose oxidation by glucose oxidase (GOD) to detect AFB1 as low as 7.1 pM. Therefore, acid-accelerated hydrolysis of NaBH4 is powerful for developing portable, cheap, and diverse gas pressure biosensing. It opens up a new way for cheap, universal, and portable biosensing.

Self-assembly of DNA-gold nanoaggregate for visual detection of thymidine kinase 1 (TK1) mRNA via lateral flow assay.

Nucleic acid lateral flow assay (NALFA) with gold nanoparticles (AuNPs) as colorimetric probes have been extensively adopted for point-of-care testing (POCT). However, the sensitivity of NALFA still needs to be improved. Herein, DNA-gold nanoaggregate (DNA-AuNA) was assembled as a signal amplification probe of NALFA for sensitive detection of tumor marker TK1 mRNA. Four functional oligonucleotides with complementary pairs were assembled to form DNA-AuNA that coupled more AuNPs to improve sensitivity. Thus, the limit of detection (LOD) was 0.36 pM, which is lower than that of conventional AuNPs-based NALFA. Moreover, the bioassay showed good reproducibility, stability, and specificity for detecting TK1 mRNA. The detection of TK1 mRNA in human serum was also satisfactory. Therefore, DNA-AuNA-based NALFA provides a sensitive method for portable detection of TK1 mRNA.

Silver/copper bimetallic nanoclusters integrating with cryonase-assisted target recycling amplification detection of Salmonella typhimurium.

An unsophisticated fluorescence-enabled strategy is brought forward to process the highly sensitive fluorescence detection of Salmonella typhimurium (S. typhimurium) which based on polyethyleneimine (PEI)-templated silver/copper nanoclusters (Ag/CuNCs) (λ excitation = 334 nm and λ emission = 466 nm) with cryonase-assisted target recycling amplification. The Ag/CuNCs nanoclusters are synthesized as fluorescent materials due to their strong and stable fluorescence characteristics and are modified with S. typhimurium aptamers to form aptamer-Ag/CuNCs probes. The probes can be adsorbed on the surface of quenching agents-polydopamine nanospheres (PDANSs), thereby inducing fluorescence quenching of the probes. Once the aptamers are bound to the target, the aptamers/targets complexes are separated from the PDANSs surface, and the Ag/CuNCs recover the fluorescence signal. The released complexes will immediately be transformed into a substrate digested by cryonase (an enzyme that can digest all types of nucleic acids), and the released targets are bound to another aptamers to initiate the next round of cleavage. This reaction will be repeated continuously until all relevant aptamers are consumed and all Ag/CuNCs are released, resulting in a significant amplification of the fluorescence signal and improved sensitivity. Using Ag/CuNCs as fluorescent probes combined with cryonase-assisted amplification strategy, the fluorescence aptasensor is constructed with detection limits as low as 3.8 CFU mL-1, which is tenfold better than without the cryonase assistance. The method developed has been applied to milk, orange juice, chicken, and egg white samples with excellent selectivity and accuracy providing an approach for the early and rapid detection of S. typhimurium in food.

Impact of hyperkalemia on hospitalization days in advanced chronic kidney disease patients with Type-2 diabetes mellitus: A prospective study.

Objective: This study aimed to explore the impact of hyperkalemia at admission on hospitalization days (HDs) among advanced chronic kidney disease patients (CKD) with type two diabetes mellitus (T2DM) in China. Methods: A total of 270 CKD patients with T2DM were prospectively selected from January 1, 2020 to December 31, 2021. These patients were divided into Group-A (n = 150, serum potassium ≤ 5.5 mmol/L) and B (n = 120, serum potassium > 5.5 mmol/L). The comparison method between the two groups was taken. Linear correlation analysis was performed using the Spearman correlation method, and multivariate analysis was tested using linear regression. Results: The study found statistically significant result between the two groups (Group-A vs Group-B): HDs (7.4 (5.3-11.2) vs 12.1 (8.2-16.5), p < 0.001), renin-angiotensin-aldosterone system inhibitors (RAASIs) (36.2% vs 55.8%, p = 0.014), systolic blood pressure (148.35 ± 19.51 vs 162.26 ± 21.31, p < 0.05), estimated glomerular filtration (eGFR) (20.35) (18.31-25.26) vs13.4 (12.50-18.50), p < 0.001, N-terminal pro-B type natriuretic peptide (NT-proBNP) (2245.42 ± 61.09 vs 3163.39 ± 85.15,p < 0.001), and Hb (88.45 ± 12.35 vs 72.26 ± 14.2, p = 0.023). Correlation analysis showed that HDs were positively correlated with age, serum potassium, systolic blood pressure, and NT-proBNP, while negatively with eGFR and Hb. After adjusting for relevant confounding variables, the multivariable linear regression analysis showed that hyperkalemia was an independent risk factor for HDs. Conclusions: Hyperkalemia could be an independent risk factor increasing HDs of advanced CKD patients with T2DM.

Oxygen Vacancy-Dependent Chemiluminescence: A Facile Approach for Quantifying Oxygen Defects in ZnO.

Defect engineering is an effective strategy to improve the catalytic activity of metal oxides, and quantitative characterization of surface defects is thus vital to the understanding and application of metal oxide catalysts. Herein, we found that ZnO nanoparticles with oxygen vacancy could trigger the luminol-H2O2 system to emit a strong chemiluminescence (CL), and the CL intensity was strongly dependent on the oxygen vacancy of the ZnO nanoparticles. The mechanism of this CL reaction was discussed by means of the electron-spin resonance spectrum, X-ray photoelectron spectrum (XPS), and CL spectrum. The oxygen vacancy-dependent CL was attributed to the ability of the oxygen vacancy to readily adsorb and further dissociate H2O2 into active •OH radicals. Taking advantage of this oxygen vacancy-dependent CL, we presented one method for quantifying the oxygen defects in ZnO. Compared with the current evaluation techniques (XPS and Raman spectroscopy), this CL method is rapid, low-cost, and easy to operate. This work introduces the CL technique into the field of material structure-property evaluation, and provides a new approach for exploring the defect function in ZnO defect engineering.

Atomic Dispersion of Zn2+ on N-Doped Carbon Materials: From Non-Activity to High Activity for Catalyzing Luminol-H2O2 Chemiluminescence.

Fe and Co single-atom catalysts (SACs) have been widely explored in many fields, while Zn SACs are still in their infancy stage. Herein, we unexpectedly found that atomically dispersed Zn2+ on N-doped carbon material (Zn-N-C) exhibited high catalytic activity on luminol-H2O2 chemiluminescence (CL) reaction. The Zn-N-C SACs were readily prepared through simple pyrolyzation of the cheap precursors (dopamine and ZnCl2). The mechanism of Zn SAC-catalyzed CL reaction of luminol-H2O2 was investigated in detail. The activity of Zn SACs originated from the Zn-N sites in the Zn-N-C structure. The monoatomic dispersion makes Zn2+ catalytic performance change from no activity to high activity in luminol-H2O2 CL reaction. This study demonstrated the particularity of the monatomic metal catalyst over the conventional metal ion. This work provides the unprecedented perspective for design of new metal SACs in CL reaction.

Portable and Label-Free Sensor Array for Discriminating Multiple Analytes via a Handheld Gas Pressure Meter.

Cross-reactive sensor arrays are useful for discriminating multiple analytes in a complex sample. Herein, a portable and label-free gas pressure sensor array was proposed for multiplex analysis via a handheld gas pressure meter. It is based on the interaction diversity of analytes with catalase-like nanomaterials, including Pt nanoparticles (PtNP), Co3O4 nanosheets (Co3O4NS), and Pt-Co alloy nanosheets (PtCoNS), respectively. Thus, the diverse influence of analytes on the catalase-like activity could be output as the difference in the gas pressure. By using principal component analysis, eight proteins were well distinguished by the gas pressure sensor array at the 10 nM level within 12 min. Moreover, different concentrations of proteins and mixtures of proteins could likewise be discriminated. More importantly, the effective discrimination of proteins in human serum and discrimination of five kinds of cells further confirmed the potential of the gas pressure sensor array. Therefore, it provides a portable, cheap, sensitive, and label-free gas pressure sensor array, which is totally different from the reported sensor arrays and holds great potential for portable and cheap discrimination of multiple analytes.

Ratiometric fluorescent probe: a sensitive and reliable reporter for the CRISPR/Cas12a-based biosensing platform.

Due to the excellent activity of trans-cleavage and target recognition, the recently discovered CRISPR/Cas12a systems provide a promising opportunity for designing fluorescence biosensing. In the reported CRISPR/Cas12a-based biosensing platform, TaqMan probe is widely used as the reporter. However, the TaqMan probe provides single-wavelength fluorescence changes, which is easily influenced by various analyte-independent confounding factors to produce false-positive signals. In this study, a ratiometric fluorescent probe was designed to act as the reporter of a CRISPR/Cas12a-based system. As a proof-of-concept, fluorescein (FAM) and tetramethylrhodamine (TAMRA) were chosen as the two fluorescence dyes to label one short ssDNA at 5' and 3' ends, respectively, which was designed as one ratiometric fluorescent probe. When the ratiometric probe excites at 480 nm, duo to FRET effect, the probe emitted the 580 nm-fluorescence of TAMRA. The activated Cas12a can cleave the dual-labeled ssDNA, resulting in a decrease in the TAMRA's fluorescence and an increase in the FAM's fluorescence. This dual-response fluorescent probe can act as the reporter of the CRISPR/Cas12a-based biosensing platform. Compared with the classic TaqMan, CRISPR/Cas12a-based biosensing with the ratiometric probe as the reporter not only exhibited higher sensitivity but also could distinguish and avoid false positive signals.