Search

Simultaneous detection of multiple breast cancer-associated miRNAs significantly raises the accuracy and reliability of early diagnosis. In this work, disposable carbon fiber paper serves as the biosensing interface, linking DNA probes via click chemistry to efficiently capture targets and signals efficiently. DNA probes have multiple recognition domains that trigger a cascade reaction through the helper probes and targets, resulting in two signals output. The signals are centrally encapsulated in the pore of the MIL-88(Fe)-NH2. The signal carriers are directed by signal probes to the recognition domains that correspond to the DNA probes. The biosensor is selective and stable, and it can quantify miRNA-21 and miRNA-155 simultaneously with detection limits of 0.64 and 0.54 fmol/L, respectively. Furthermore, it demonstrates satisfactory performance in tests conducted with normal human serum and cell lysate. Overall, this method makes a satisfactory exploration to realize an inexpensive and sensitive biosensor for multiple biomarkers.

Resting sweat analysis could provide unique insight into the metabolic levels of physiological and pathological states. However, the low secretion rate of resting sweat and the low concentration of metabolic molecules pose challenges for the development of noninvasive wearable sensors. Here, we demonstrated a wearable patch for the precise analysis of uric acid at rest. Fe single-atom nanozymes (FeSAs) with excellent electrocatalytic activity were used to develop a sensor for selective catalysis of uric acid (UA, 1–425 μM), and the catalytic mechanism of UA was later explored by density functional theory. In addition, polyaniline was integrated into the wearable patch for pH detection; thus, accurate analysis of sweat UA molecules can be achieved by pH calibration. Then, we explored the possibility of collecting resting sweat with different ratios of agarose hydrogels to reduce the sweat accumulation time. Finally, the possibility of a wearable patch for accurate UA detection in volunteer sweat samples was experimentally verified. We believe that our work provides novel insights and ideas for the analysis of resting sweat using wearable devices, further driving advancements in the field of personalized medicine.

The untested empirical medications exacerbated the development of multidrug-resistant Mycobacterium tuberculosis(MDR-TB). Here, we develop a rapid and specific method based on loop-mediated isothermal amplification and duplex-specific nuclease for distinguishing rifampicin-resistant M. tuberculosis. Three probes were designed for the codons 516, 526, and 531 on the RNA polymerase β-subunit (rpoB) gene. These three sites accounted for more than 90% of the total mutations of the ropB gene in the rifampicin-resistant strain. The approach can perform simultaneous and sensitive detection of three mutant sites with the actual detection limit as 10 aM of DNA and 62.5 cfu·mL–1of bacteria in 67 min under isothermal conditions. Moreover, the positive mode of the approach for MDR-TB can not only deal with the randomness and diversity of mutations but also provide an easier way for medical staff to read the results. Therefore, it is a particularly valuable method to handle major and urgent MDR-TB diagnostics.

High-efficiency measurement of nitrite (NO2−) is of significant importance for both food safety and the management of health problems. In the present study, we established a fluorescent sensor for the selective detection of nitrite using 3-acetoacetyl-7-diethylaminocoumarin (ADC) and 3-aminophenol (3-Aph) based on a simplified Griess reaction and inner filter effect (IFE). Under strong acidic conditions, the rapid reaction between 3-Aph and nitrite formed an azoic compound (AZO) with the color changing from colorless to brown. The complementary spectral overlap between the absorption of AZO and the excitation of ADC induced IFE, leading to the fluorescence quenching of ADC. Under the selected optimal conditions, the proposed sensor exhibited a good linear relationship in the range from 0.1 μM to 50 μM (R2= 0.9938) with the detection limit of 24.6 nM. Besides, the detection of nitrite in real pickle and bacon samples was successful and showed a maximum of 5% relative error with acceptable recoveries, demonstrating that this promising strategy can be employed for nitrite analysis in real-time applications.

In this work, a new application of Mn-doped ZnS quantum dots (Mn-ZnS QDs) was developed to screen chloramphenicol (CAP) and tetracycline (TC) residues simply and rapidly. Mn-ZnS QDs synthesized by a hydration method and modified by l-cysteine for better stability emit phosphorescence at 583 nm with the excitation wavelength at 289 nm. Based on the overlap of the Mn-ZnS QDs excitation spectra and CAP or TCs ultraviolet spectra, the excited light of the Mn-ZnS QDs was partially absorbed by CAP or TCs owing to the inner-filter effect (IFE), leading to a decrease in the phosphorescence intensity. The phosphorescence intensities of the samples prepared by mixing different TCs and CAP were in good agreement with the expected results from adding a single antibiotic sample. Therefore, the total molar concentrations of CAP and TCs could be screened based on the linear equation of a single standard substance. Represented by tetracycline (TC), as a member of the tetracycline family, under optimized conditions, showed a good linear relational concentration range over 4 orders of magnitude from 50 to 1.5 × 105nM with a limit of detection (LOD; S/N ratio = 3) down to 8.6 nM. The phosphorescent sensor was also used to detect total TCs in actual samples successfully. The evaluations of the recovery rate and selectivity were good. These results demonstrated that the presented phosphorescent sensor can be a simple and rapid screening platform for CAP and TCs.

Different valence states of chromium ions possess huge differences in toxicity. Hence, it is an innovative idea to design a reasonable probe to detect Cr according to the toxicity characteristics of different valence states. We report a novel, rapid, simple and accurate probe for the detection of Cr3+and Cr6+ions. As a probe, gold nanoparticles (Au NPs) are successfully modified using tartaric acid (TA) and 2-[4-(2-hydroxyethyl)-1-piperazinyl] ethanesulfonic acid (HEPES) viaa two-step modification; the probe shows an increase in the sensitivity towards Cr6+and decreases towards Cr3+, which is consistent with their toxicity characteristics, benefiting the assessment of total Cr toxicity. The proposed probe achieves considerable two-channel (ultraviolet absorption spectrum and naked eye vision) detection of Cr3+and Cr6+providing wide linearity regions and low detection limits. Meanwhile, the results of the interference experiments and analysis of the real samples showed high selectivity and accuracy of the proposed method. With popularization, this method possesses great potential in environmental monitoring and control.

Carbon dots (CDs) having low cost and low toxicity and synthesized viaa green route were applied to establish a fluorescent nanoprobe for the measurement of glyphosate. The synthesis was realized viaa one-pot hydrothermal procedure using Sophora japonicaleaves as the carbon source. It was found that electron transfer occurred between Fe3+and the as-prepared CDs. Therefore, Fe3+exhibited a specific dynamic-quenching toward CDs. However, the electron transfer process was inhibited by glyphosate. The fluorescence of the quenched CDs/Fe3+system was recovered by the addition of glyphosate. It resulted from the strong complexation between Fe3+and the functional groups (like –PO3H2and –COOH) in the glyphosate molecule. These functional groups captured Fe3+from the CD/Fe3+system to reduce the electron transfer. With such a design, the rapid detection of glyphosate could be realized by this turn-on fluorescent sensor based on the CD/Fe3+system. Under optimal conditions, the CD/Fe3+system showed a concentration-dependent fluorescent response toward glyphosate in the linear range from 0.1 to 16 ppm. The limit of detection was calculated to be as low as 8.75 ppb (3σ/S). In addition, the successful detection of glyphosate in real samples with satisfactory recoveries exhibited a practical application of the CD/Fe3+nanoprobe in food safety and environmental monitoring.

Estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor-2 (HER2), and Ki67 are four crucial biomarkers used in the clinical diagnosis of breast cancer. Accurate detection of these biomarkers is essential for an effective diagnosis and treatment. MOF-based micronano motors (MOFtors) are promising for various applications, including environmental remediation, targeted nanosurgery, and biomarker detection. This paper presents a clinically feasible diagnostic electrochemical micronano motor biosensor, built on a miniature swimmer, for the multiplex detection and grading of breast cancer biomarkers. We designed a biosensor, named MOFtor-MSEM, incorporating aptamers and antibodies functionalized on SiO2@Co–Fe-MOF, which acts as a miniature swimmer in solution. The SiO2@Co–Fe-MOF serves as the body, while complementary double-chain-linked antibodies function as paddles. In a homogeneous solution, when a positive voltage is applied to the working electrode, the electrostatic interaction between the neutral SiO2@Co–Fe-MOF and the negatively charged complementary double-linked antibody causes the antibody to move toward the electrode and then regress due to water resistance. This back-and-forth motion propels the miniature swimmer, enabling it to move the target analyte through the solution. The sensor features an automatic “sample-amplifying signal-output” process, achieving simultaneous signal amplification and output of four electrochemical signals on a single nanomaterial, a significant challenge in electrochemical sensing. The biosensor boasts a short detection time of 40 min, compared to approximately 1 week for current clinical tissue testing. Additionally, the bioplatform selectively detects HER2, ER, Ki67, and PR in the range of 0–1500 pg/mL, with detection limits of 0.01420, 0.03201, 0.01430, and 0.01229 pg/mL, respectively.

Circulating tumor DNA (ctDNA), as a next-generation tumor marker, enables early screening and monitoring of cancer through noninvasive testing. Exploring the development of new methods for ctDNA detection is an intriguing study. In this work, a unique electrochemical biosensor for the ctDNA detector was constructed in the first utilizing Fe single-atom nanozymes-carbon dots (SA Fe-CDs) as a signaling carrier in collaboration with a DNA walker cascade amplification strategy triggered by nucleic acid exonuclease III (Exo III). The electrochemical active surface area of AuNPs/rGO modified onto a glassy carbon electrode (AuNPs/rGO/GCE) was about 1.43 times that of a bare electrode (bare GCE), with good electrical conductivity alongside a high heterogeneous electron transfer rate (5.81 × 10–3cm s–1), that is, as well as the ability to load more molecules. Sequentially, the DNA walker cascade amplification strategy driven by Exo III effectively converted the target ctDNA into an amplified biosignal, ensuring the sensitivity and specificity of ctDNA. Ultimately, the electrochemical signal was further amplified by introducing SA Fe-CDs nanozymes, which could serve as catalysts for 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation with facile responding (Vmax= 0.854 × 10–6M s–1) and robust annexation (Km= 0.0069 mM). The integration of the triple signal amplification approach achieved detection limits as low as 1.26 aM (S/N= 3) for a linearity spanning from 5 aM to 50 nM. In this regard, our proposal for a biosensor with exceptional assay properties in complicated serum environments had great potential for early and timely diagnosis of cancer.

In this study, a label-free fluorescent probe based on l-cysteine modified copper nanoclusters (l-cys–Cu NCs) is applied to directly detect fluazinam viathe inner filter effect. l-Cys–Cu NCs are synthesized through a simple method and show green fluorescence. The as-prepared l-cys–Cu NCs have an optimal emission wavelength of 497 nm under excitation of 365 nm. In the presence of fluazinam, the fluorescence of the Cu NCs is significantly quenched due to the abundant Cu NC affinitive sites recognizing fluazinam through molecular interactions. In addition, the absorption of fluazinam obviously overlaps with the excitation of the Cu NCs. Thus, an effective inner filter effect occurs. Under optimal conditions, the fluorescent probe shows a reliable linear relationship ranging from 0.05 to 25 μM with a correlation coefficient of 0.9953. And the detection limit of this probe is 1.4 nM (S/N = 3). The proposed fluorescent probe is applied to real samples with satisfactory results, indicating promising applications in environmental monitoring.

A luminescent amino-functionalized metal–organic framework (Cu–MOFs) was synthesized from 2-aminoterephthalic acid and Cu(ii) ions by a solvothermal method. Cu–MOFs displayed blue fluorescence with a peak at 430 nm under 330 nm excitation. Its structure was characterized by FTIR, TEM, XRD, and XPS. The fluorescence of the Cu–MOFs was quenched by Fe3+in aqueous solutions. The limit of detection was 0.5 μM, and the linear working range extended from 2 μM to 35 μM. Additionally, a good logarithmic relationship between relative fluorescence intensity (F/F0) and Fe3+concentrations ranging from 2 to 180 μM was obtained with a detection limit of 1.56 μM (R2= 0.9975). No clear interference was observed when challenged with a wide variety of cations and anions. The recoveries from spiked real water samples were in the range of 91.7–107.7%, and the detection results were consistent with inductively coupled plasma mass spectrometry (ICP-MS) results. Therefore, the fluorescent sensor has great potential in environmental monitoring.

In recent years, copper-based nanomaterials have been widely used in the study of glucose sensors because of its high sensitivity. In this work, a sensitive and selective electrochemical enzyme-free glucose sensor was successfully constructed using a composite of copper oxide nanowires (CuO NWs), molybdenum disulfide (MoS2) and gold nanoparticle (AuNPs). This composite was systematically characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The sensor performance and interface property of the Au electrode modified by NF/AuNPs/CuO-MoS2 were measured by cyclic voltammetry (CV) and chronoamperometric measurements(i-t). Under optimal condition, the proposed sensor shows sensitivity value of 872.71 uA cm[?]2 mM[?]1 for glucose, with detection range from 0.5 uM to 5.67 mM and detection limit of 0.5 uM. The study also confirms satisfactory selectivity, reproducibility, and stability of the constructed sensor. This NF/AuNPs/CuO NWs-MoS2 sensor performance toward normal human serum spiked with glucose is determined with RSD less than 4.71%, indicating superior potential for the practical quantitative analysis of glucose in serum samples.

Guanine (G) and adenine (A) are two important components of nucleic acid and some small molecules in an organism. In this paper, we developed a new and convenient biosensor for the simultaneous determination of G and A based on overoxidized polypyrrole/multi- walled carbon nanotube and molybdenum disulfide modified glassy carbon electrode (PPyox/ MWNTs-MoS2/GCE). The composite material exhibited remarkable electro-catalytic properties toward the oxidation of G and A due to its large surface area and fast electron transfer. The oxidation peak positions of G and A were at 0.73 V and 1.03 V, respectively, which allowed simultaneous detection of the two substances in coexistence solution. The designed biosensor exhibited linear responses to G and A both in the ranges 5-30 uM and 30-120 uM, with detection limits (S/N = 3) of 1.6 uM (G) and 1.7 uM (A), respectively. Moreover, interferences from some coexisting electro-active species including inorganic ions, glucose, glycine and citric acid were nearly negligible. Further, the sensing strategy was successfully used for the detection of G and A in real samples with satisfactory results, indicating a potential application for the simultaneous electrochemical detection of G and A.

In the present study, we fabricated a 3 × 3 colorimetric sensor array using nanomaterials/dyes as sensing dots to discriminate 8 commercial baijiu samples. Sensing dots can cross-respond to baijiu samples, enabling color changes of the sensor array and subsequently providing special fingerprints. Eight baijiu samples were successfully discriminated using principal component analysis (PCA), linear discriminant analysis (LDA) and hierarchical cluster analysis (HCA) without misclassification. A radial basis function neural network (RBFN) was employed to determine the fitting relationship between the predicted samples and the actual samples. From all the evidence, we draw the conclusion that this 3 × 3 NP-dye colorimetric discrimination system can perform successful distinction of baijiu. Moreover, a separation tendency of different baijiu samples was shown viaalcoholic-strength (38° and 52°) without detection of alcoholic-strength. This effort may benefit quality control of baijiu in the market and in mass-production in the factory.

Accurate detection of cancer-associated mRNAs is beneficial to early diagnosis and potential treatment of cancer. Herein, for the first time, we developed a novel CRISPR/Cas12a-powered electrochemical/fluorescent (EC/FL) dual-mode controlled-release homogeneous biosensor for mRNA detection. A functionalized ssDNA P2-capped Fe3O4–NH2loaded with methylene blue (P2@MB–Fe3O4–NH2) was synthesized as the signal probe, while survivinmRNA was chosen as the target RNA. In the presence of the target mRNA, the nicking endonuclease-mediated rolling circle amplification (NEM-RCA) was triggered to produce significant amounts of ssDNA, activating the collateral activity of Cas12a toward the surrounding single-stranded DNA. Thus, the ssDNA P1 completely complementary to ssDNA P2 was cleaved, resulting in that the ssDNA P2 bio-gate on Fe3O4–NH2could not be opened due to electrostatic interactions. As a result, there was no or only a little MB in the supernatant after magnetic separation, and the measured EC/FL signal was exceedingly weak. On the contrary, the ssDNA P2 bio-gate was opened, enabling MB to be released into the supernatant, and generating an obvious EC/FL signal. Benefiting from the accuracy of EC/FL dual-mode cross-verification, high amplification efficiency, high specificity of NEM-RCA and CRISPR/Cas12a, and high loading of mesoporous Fe3O4–NH2on signal molecules, the strategy shows aM-level sensitivity and single-base mismatch specificity. More importantly, the practical applicability of this dual-mode strategy was confirmed by mRNA quantification in complex serum environments and tumor cell lysates, providing a new way for developing a powerful disease diagnosis tool.

In recent years, copper-based nanomaterials have been widely used in the study of glucose sensors because of its high sensitivity. In this work, a sensitive and selective electrochemical enzyme-free glucose sensor was successfully constructed using a composite of copper oxide nanowires (CuO NWs), molybdenum disulfide (MoS2) and gold nanoparticle (AuNPs). This composite was systematically characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The sensor performance and interface property of the Au electrode modified by NF/AuNPs/CuO-MoS2 were measured by cyclic voltammetry (CV) and chronoamperometric measurements(i-t). Under optimal condition, the proposed sensor shows sensitivity value of 872.71 μA cm−2 mM−1for glucose, with detection range from 0.5 μM to 5.67 mΜ and detection limit of 0.5 μM. The study also confirms satisfactory selectivity, reproducibility, and stability of the constructed sensor. This NF/AuNPs/CuO NWs-MoS2sensor performance toward normal human serum spiked with glucose is determined with RSD less than 4.71%, indicating superior potential for the practical quantitative analysis of glucose in serum samples.

Guanine (G) and adenine (A) are two important components of nucleic acid and some small molecules in an organism. In this paper, we developed a new and convenient biosensor for the simultaneous determination of G and A based on overoxidized polypyrrole/multi- walled carbon nanotube and molybdenum disulfide modified glassy carbon electrode (PPyox/ MWNTs-MoS2/GCE). The composite material exhibited remarkable electro-catalytic properties toward the oxidation of G and A due to its large surface area and fast electron transfer. The oxidation peak positions of G and A were at 0.73 V and 1.03 V, respectively, which allowed simultaneous detection of the two substances in coexistence solution. The designed biosensor exhibited linear responses to G and A both in the ranges 5–30 μM and 30–120 μM, with detection limits (S/N = 3) of 1.6 μM (G) and 1.7 μM (A), respectively. Moreover, interferences from some coexisting electro-active species including inorganic ions, glucose, glycine and citric acid were nearly negligible. Further, the sensing strategy was successfully used for the detection of G and A in real samples with satisfactory results, indicating a potential application for the simultaneous electrochemical detection of G and A.