Specific Recognition Ability Research Articles

Preparation of magnetic molecularly imprinted polymers for the selective extraction of strobilurin fungicides in agricultural products

In this study, the novel magnetic molecularly imprinted polymers were successfully synthesized by surface imprinting technique and used as magnetic adsorbent for extracting six strobilurin fungicides from agricultural products. The magnetic molecularly imprinted polymers showed the typical core-shell structure with high maximum adsorption capacity (42.7 mg/g) and rapid adsorption equilibration (3 min) and specific recognition ability. The parameters (elution solvent, elution time, adsorption time, loading solvent and solution pH) in magnetic solid phase extraction were evaluated. Under the optimum adsorption and desorption condition, the magnetic solid phase extraction process based on magnetic molecularly imprinted polymers coupled with high performance liquid chromatography-tandem mass spectrometry was developed for the sensitive detection of strobilurin fungicides from agricultural products. The developed method presented good linearity (5–200 ng/mL) with correlation coefficients (R2) ≥ 0.9990. The limits of detection and quantification were 0.03–0.49 ng/g and 0.09–1.64 ng/g, respectively. At the three different concentration (20, 50, 100 ng/g) spiked in agricultural products, the good recovery (71.5%−115.8%) was obtained and the relative standard deviations were below 8.3%. These results indicated that this established method was sensitive, accurate, selective and reproducible.

MOF-On-MOF Dual Enzyme-Mimic Nanozyme with Enhanced Cascade Catalysis for Colorimetric/Chemiluminescent Dual-Mode Aptasensing.

A novel metal-organic framework (MOF)-on-MOF dual enzyme-mimic nanozyme was designed as enhanced cascade signal amplification for the colorimetric and chemiluminescent (CL) dual-mode aptasensing. The MOF-on-MOF hybrid is composed of MOF-818 with catechol oxidase-like activity and iron porphyrin MOF [PMOF(Fe)] with peroxidase-like activity, called MOF-818@PMOF(Fe). MOF-818 can catalyze the 3,5-di-tert-butylcatechol substrate and produce H2O2 in situ. Subsequently, PMOF(Fe) catalyzes H2O2 to produce reactive oxygen species, which oxidize 3,3',5,5'-tetramethylbenzidine or luminol to produce color or luminescence. Thanks to the nano-proximity effect and the confinement effect, the efficiency of the biomimetic cascade catalysis is greatly improved, which in turn generates enhanced colorimetric and CL signals. Taking the detection of chlopyrifos as an example, the prepared dual enzyme-mimic MOF nanozyme is combined with the aptamer with specific recognition ability to develop a colorimetric/CL dual-mode aptasensor for highly sensitive and selective detection of chlorpyrifos. The proposed MOF-on-MOF dual nanozyme-enhanced cascade system may provide a new pathway for the further development of a biomimetic cascade sensing platform.

(2 0 0) Facet regulation on Bi12O17Cl2 nanosheets driven charge separation for enhancing photoelectrochemical ciprofloxacin aptasensing

Photoelectrochemical (PEC) aptasensor with high sensitivity, quick response, facile miniaturization, and low-cost has emerged as a prospectively method for detecting ciprofloxacin (CIP). A crucial issue in constructing PEC aptasensor is how to modulate photogenerated charges behaviors of photoelectric active materials. Bi12O17Cl2 nanosheets with exposed (200) facets have been designed and prepared in this work, which exhibited the open charge channel characteristic, narrow band gap, strong visible light harvesting ability, and significantly broadened light absorption range. These characteristics are conducive to the effective generation, separation and transfer of charges for possessing strong photocurrent signal. Based on the Bi12O17Cl2 nanosheets with exposed (200) facets and CIP aptamer with specific recognition ability, a PEC aptasensor was constructed for detecting CIP. The PEC aptasensor showed a detection range of 1.00 × 10–2–1.00 ng L–1 and the detection limit of 3.33 pg L–1 (S/N = 3). The constructed PEC aptasensor also can demonstrate good sensitivity, selectivity, reproducibility, and feasibility.

Cr(VI) anion-imprinted polymer synthesized on mesoporous silicon via synergistic action of bifunctional monomers for precise identification and separation of Cr(VI) from aqueous solution by fixed-bed adsorption.

The novel Cr(VI) anion-imprinted polymer (Cr(VI)-IIP) was prepared by a surface imprinting technique with bifunctional monomers pre-assembly system based on mesoporous silicon (SBA-15). The synthesized Cr(VI)-IIP was characterized by Fourier transmission infrared spectra (FT-IR), energy dispersive spectrometer (EDS), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray powder diffractometer, N2 adsorption-desorption and thermogravimetric analysis (TGA), proving to be with a highly ordered mesoporous structure, as well as favorable thermal stability. The saturated adsorption amount was 96.32 mg/g, which was 2.7 times higher than that of non-imprinted polymer (NIP). Kinetic experiments showed that the adsorption equilibrium state was obtained within 70 min. In addition, in the selectivity experiments, Cr(VI)-IIP exhibited strong specific recognition ability for Cr(VI) and could realize the separation of Cr(VI) and Cr(III) from an aqueous solution. The dynamic adsorption experiments exhibited that the dynamic adsorption efficiency of Cr(VI)-IIP was as high as 71.57%. Meanwhile, the dynamic regeneration experiments showed that the adsorption amount of Cr(VI)-IIP did not decrease significantly after repeating for five times. All of the findings suggested that Cr(VI)-IIP could achieve precise identification as well as efficient separation of Cr(VI) from aqueous solution.

A multifunctional fluorescence MOF material: Triple-channel pH detection for strong acid and strong base, recognition of moxifloxacin and tannic acid

A luminescent 1D metal–organic framework [Co(apba)2(H2O)2] (1) was solvothermal synthesized by using 4-(2-aminopyrimidine-5-yl)benzoic acid (Hapba) as ligand. 1 showed pronounced sensing properties with triple-channel specific recognition ability for strong acid-base and weak acid. From pH = 3.5 to 2.0, the fluorescence quenching percentage reached 1064 % per pH at 412 nm due to the protonation of –NH2. In the pH region of 3.5–4.5, 1 realizes wavelength-based pH detection depending on the wavelength shift of 30 nm from 412 nm to 382 nm originating from the protonation of nitrogen atom in pyrimidine. In the pH range of 11.5–13.4, the fluorescence quenching percentage reached 2099 % per pH relying on the interaction between OH– and uncoordinated oxygen atom on carboxylate group. This is the first example that a MOF-based pH sensor can detect strong acid-base and weak acid, and their sensitivity to pH is likewise the highest among all pH fluorescent sensors. 1 can also detect antibiotic moxifloxacin (MOX) and polyphenol compound tannic acid (TA) with the limit of detection (LOD) at the 10 ppb level. In the recognition of 1 for MOX, KSV is 2.05 × 105 M−1 (0–100 μM) and LOD reaches 43 nM, which is the first case of a MOF-based MOX sensor so far. The fluorescence response of 1 to TA is also apparent with the KSV value of 7.55 × 105 M−1 (0–0.05 μM) and LOD of 11 nM. This is as well the only instance of MOF material sensing TA to date. Moreover, 1 can continuously track MOX and TA for up to 90 days. The sensing mechanisms of pH, MOX, and TA are also discussed in detail.

Molecularly imprinted two‐dimensional photonic crystal hydrogel sensor for the detection of gatifloxacin

AbstractUsing polystyrene two‐dimensional photonic crystal as template, gatifloxacin (GTFX) as imprinting molecule, methanol as solvent, acrylic acid as functional monomer, ethylene glycol dimethyl acrylate as crosslinking agent and 2,2‐diethyloxyacetophenone as initiator, after UV initiation polymerization the GTFX molecularly imprinted two‐dimensional photonic crystal hydrogel (GTFX‐MIPCH) sensor was prepared. The response performance of the hydrogel was investigated by measuring the diameter change of the Debye ring. The experimental results showed that the prepared GTFX‐MIPCH has a sensitive response to GTFX. When the concentration of GTFX increases from 0 to 1 × 10−4 mol L−1, the diameter of the Debye ring decreases by 8.50 mm, the corresponding particle spacing increases by 29.1 nm, and the color of the sensor changes from purple to orange. Also there was a linear relationship between the change of particle spacing (Δd) and the logarithm of GTFX concentration (lg c) in the range 10−12–10−6 mol L−1. It is noteworthy that the limit of detection of GTFX‐MIPCH is as low as 10−14 mol L−1. In addition, in a solution of GTFX analogues enrofloxacin, levofloxacin, ciprofloxacin and norfloxacin, the change of particle spacing of the GTFX‐MIPCH sensor is 13.3, 11.6, 11.1 and 10.3 nm respectively, indicating that GTFX‐MIPCH has good specific recognition ability for GTFX. Moreover, GTFX‐MIPCH shows good reusability and can also be used for the detection of GTFX in water samples. This GTFX‐MIPCH can achieve a visual detection effect on GTFX through the Debye ring and color change. © 2023 Society of Industrial Chemistry.

Migration detection of six aromatic amines in polyamide food contact materials by HPLC after molecularly imprinted polymer pipette tip solid phase extraction

Some food contact materials (FCMs) may contain aromatic amines (AAs), which would migrate to food and pose a serious threat to human health. An extraction and determination method for AAs was established using pipette tip solid-phase extraction (PTSPE) combined with high performance liquid chromatography-photodiode array detector (HPLC-PAD). The PTSPE was based on molecularly imprinted polymer (MIP) monolith, which was synthesized in situ polymerization using benzidine as template molecule and 4-vinylpyridine as functional monomer. It was applied for selective extraction of six AAs from FCMs, including benzidine, 3,3′-dimethyl-4,4′-diaminodiphenylmethane, 2-methoxy-5-methylaniline, 3,3′-dimethoxybenzidine, 4,4′-methylenedianiline and 4-aminobiphenyl. The MIP monolith showed highly specific recognition and good adsorption ability for the six AAs, the imprinting factor for 4,4′-methylenedianiline can reach 4.29 and the adsorption capacity for 4-aminobiphenyl can reach 112.3 mg g−1. The linear range of the determination method for the six AAs was 0.60–500 µg kg−1 (R2＞0.997), the limits of quantitation was 0.60–4.50 µg kg−1 and the limits of detection (S/N = 3) was 0.20–1.50 µg kg−1. The MIP-PTSPE-HPLC-PAD method was applied for the migration detection of six AAs from polyamide kitchenware and the absolute recovery were 81.7–110.9%.

A universal approach for sensitive and rapid detection of different pathogenic bacteria based on aptasensor-assisted SERS technique.

An assembled-aptasensor based on Fe3O4@Au@Ag nanocomposites grafting onto the gold foil was prepared, which can be developed into a universal approach for sensitive and rapid detection of various pathogenic bacteria, such as Escherichia coli (E. coli), Salmonella typhimurium (S. typhimurium), Staphylococcus aureus (S. aureus), Listeria monocytogenes (L. monocytogenes), Pseudomonas aeruginosa (P. aeruginosa), and Shigella flexneri (S. flexneri). Firstly, the gold foil paper was modified with thiolated capture probe and SERS tag in proportion, and at the same time, the specific thiolated aptamer probe for corresponding pathogenic bacteria was fixed with Fe3O4@Au@Ag nanocomposites. An obvious Raman signal can be subsequently increased about 106 times by the external electromagnetic field enhancement at the "hot spots" caused by the hybridization of aptamer and capture probe. But in the presence of target pathogenic bacteria, Raman intensity will decrease as Fe3O4@Au@Ag nanocomposites are dissociated from gold foil. Thus, all of the concentrations of the six kinds of pathogenic bacteria both in PBS and liquorice extract showed an obvious negative linear correlation with the Raman intensity of SERS tag in the range of 10-107CFU/mL with detection limits were all lower than 10CFU/mL. And there was no significant difference between our method and the plate counting method. Besides, the assembled-aptasensor had superior specific recognition ability even in the mixed interfering bacteria. Our study showed that this assembled-aptasensor had good specific detection ability to a variety of foodborne pathogens based on magnetic field-assisted SERS technique, which can be used for rapid and sensitive detection of a variety of pathogens in complex substrates.

One-Pot Assay for Rapid Detection of Benzimidazole Resistance in Venturia carpophila by Combining RPA and CRISPR/Cas12a.

High resistance to benzimidazole fungicides in Venturia carpophila is caused by the point mutation E198K of the β-tubulin (TUB2) gene. Traditional methods for detection of fungicide resistance are time-consuming, which are routinely based on tedious operation, reliance on expensive equipment, and specially trained people. Therefore, it is important to establish efficient methods for field detection of benzimidazole resistance in V. carpophila to make suitable management strategies and ensure food safety. Based on recombinase polymerase amplification (RPA) combined with CRISPR/Cas12a, a rapid one-pot assay ORCas12a-BRVc (one-pot RPA-CRISPR/Cas12 platform) was established for the detection of benzimidazole resistance in V. carpophila. The ORCas12a-BRVc assay enabled one-pot detection by adding components at the bottom and wall of the tube separately, solving the problems of aerosol contamination and decreased sensitivity caused by competing DNA substrates between Cas12a cleavage and RPA amplification. The ORCas12a-BRVc assay could accomplish the detection with a minimum of 7.82 × 103 fg μL-1 V. carpophila genomic DNA in 45 min at 37 °C. Meanwhile, this assay showed excellent specificity due to the specific recognition ability of the Cas12a-crRNA complex. Further, we combined a method that could rapidly extract DNA from V. carpophila within 2 min with the ORCas12a-BRVc to achieve more rapid and simple detection of V. carpophila with benzimidazole resistance in fields. The ORCas12a-BRVc assay has the advantages of simplicity, rapidity, high sensitivity, high specificity, and ease of operation without the need for precision instruments and the need to isolate and culture pathogens. This assay is the first application of the one-pot platform based on the combination of RPA and CRISPR/Cas12a in fungicide resistance detection and can be used for monitoring of resistant populations in fields, providing guidance on making suitable management strategies for peach scab.

Synthesis of a magnetic crown ether ion imprinted polymer material for the selective adsorption of lithium

OS@FeSi@CE-OH has specific recognition ability for Li+and solves the problems of difficult separation and recovery of powder adsorbent.

Dummy Template-Based Molecularly Imprinted Membrane Coating for Rapid Analysis of Malachite Green and Its Metabolic Intermediates in Shrimp and Fish

A novel malachite green molecularly imprinted membrane (MG-MIM) with specific selectivity for malachite green (MG) and leucomalachite green (LMG) was prepared using a hydrophobic glass fiber membrane as the polymer substrate, methyl violet as a template analog, 4-vinyl benzoic acid as the functional monomer, and ethyleneglycol dimethacrylate as the crosslinking agent. MG-MIM and non-imprinted membrane (NIM) were structurally characterized using scanning electron microscopy, surface area analyzer, Fourier-transform infrared spectrometer and synchronous thermal analyzer. The results showed that MG-MIM possessed a fluffier surface, porous and looser structure, and had good thermal stability. Adsorption properties of MG-MIM were investigated under optimal conditions, and adsorption equilibrium was reached in 20 min. The saturated adsorption capacities for MG and LMG were 24.25 ng·cm-2 and 13.40 ng·cm-2, and the maximum imprinting factors were 2.41 and 3.20, respectively. Issues such as "template leakage" and "embedding" were resolved. The specific recognition ability for the targets was good and the adsorption capacity was stable even after five cycles. The proposed method was successfully applied for the detection of MG and LMG in real samples, and it showed good linear correlation in the range of 0 to 10.0 μg·L-1 (R2 = 0.9991 and 0.9982), and high detection sensitivity (detection limits of MG and LMG of 0.005 μg/kg and 0.02 μg·kg-1 in shrimp, and 0.005 μg/kg and 0.02 μg/kg in fish sample). The recoveries and relative standard deviations were in the range of 76.31-93.26% and 0.73-3.72%, respectively. The proposed method provides a simple, efficient and promising alternative for monitoring MG and LMG in aquatic products.

Synthesis of dummy-template molecularly imprinted polymers as solid-phase extraction adsorbents for N-nitrosamines in meat products

In this study, the dummy template molecularly imprinted polymers were firstly prepared by precipitation polymerization method using benzhydrol, 5-nonanol and N-formylpyrrolidine as template molecules and methacrylic acid as functional monomer. The obtained polymers were characterized and showed spherical particles with loose and porous surface. The dynamic and static adsorption experiments indicated that the polymers exhibited large adsorption capacity, high adsorption efficiency and specific recognition ability towards N-nitrosamines. The parameters of solid phase extraction process were carefully optimized. Under the optimized conditions, the solid phase extraction process based on dummy molecularly imprinted polymers coupled with high performance liquid chromatography-tandem mass spectrometry for analyzing N-nitrosamine in various processed meat products was established. This proposed method showed good linearity (R2 ≥ 0.9985), and the limits of detection and the limits of quantification were in the range of 0.03–0.65 ng/g and 0.1–1.95 ng/g, respectively. With three spiked concentrations (5, 10, and 20 ng/g), satisfactory recoveries (61.0–105.2 %) were also obtained with relative standard deviations between 1.20 and 9.76 %. Those results demonstrated that the method for N-nitrosamine possessed the advantages of high selectivity, good reproducibility and high sensitivity, providing great convenient method for enriching and detecting N-nitrosamine in complex food matrix.

High-sensitivity copper(II) sensor based on a protein/ion-imprinted polymer cooperative recognition strategy

Despite the promise of ion imprinting technology for the development of electrochemical sensors for heavy metals, improved selectivity and stability are required for practical applications. Herein, a dual recognition strategy based on a protein and an ion-imprinted polymer (IIP) was proposed to develop highly sensitive sensors for copper(II) ions (Cu2+). On Bovine serum albumin (BSA) and graphene oxide (GO)-loaded gold nanoparticles (GO/Au NPs) modify the gold electrode surface, an a Cu2+ IIP was formed on the electrode by electropolymerization. After Cu2+ was removed from IIP, the imprinted holes with a specific recognition ability for Cu2+ were obtained. In the prepared sensor, Cu2+ recognition sites were present in both BSA and the IIP, thus providing a dual recognition strategy for selective Cu2+ detection. Furthermore, owing to the amplification effect of GO/Au NPs, the sensor showed high sensitivity. With potassium ferricyanide/potassium ferrocyanide as a probe, the logarithm of the Cu2+ concentration was proportional to the sensor current response within the range of 1–8000 × 10−14 mol/L, and the detection limit was 1.12 × 10−15 mol/L. Moreover, for Cu2+ detection in actual samples, the sensor exhibited a recovery rate of 93.2–105.6 %.

Turning Agroforestry Waste into Value-Added Fluorescent Carbon Quantum Dots for Effective Detection of Fe3+ in an Aqueous Environment

In the context of the circular economy, the high quantity of agroforestry waste should be transformed into sustainable and high-value materials to abate pollution, CO2 emissions, and expensive waste disposal. Herein, the agroforestry waste of apple leaves was initially used as a precursor to extract the value-added nanomaterial carbon quantum dots (CQDs) by way of an easy hydrothermal strategy without complicated purification processes, as extracted CQDs doped with N and P possess a typical graphite-like structure, a fine particle size of 2.0 nm, and excitation-dependent photoluminescence (PL) behavior. The doping of N and P endows CQDs with a much higher quantum yield (18.1%), good water solubility, high fluorescence stability, and specific recognition ability for the detection of Fe3+. The fluorescence of CQDs could be quickly quenched by Fe3+ within 1 min and recovered with the addition of ascorbic acid, suggesting the recyclability of the prepared CQD-based fluorescent probe. Systematic analyses support that a synergistic mechanism of static fluorescence quenching and inner filter effect was involved in the detection of Fe3+ by CQDs, showing a linear range between 0 and 160 μM and a limit of detection (LOD) of 4.0 μM. Furthermore, the feasibility of detecting Fe3+ by CQDs in practice was verified by tap water/lake water samples. The present work evinces that apple leaves are useful in producing green and low-cost CQDs as a promising fluorescent probe for sensitive, rapid, and selective detection of Fe3+ in an aqueous environment.

Multi-walled carbon nanotubes as a platform for Immunoglobulin G attachment

Nanomaterials have been extensively used in different applications due to their peculiar characteristics and nanoscale dimensions. Among nanoparticles, carbon-based nanomaterials are becoming highly attractive for biomedical applications such as diagnosis, tissue engineering, drug delivery, and biosensing. The conjugation of carbon-based nanomaterials with antibodies combines the properties of these materials with the specific and selective recognition ability of the antibodies to antigens. The present work proposes a process intensification approach for immunoglobulin G (IgG present in rabbit serum) attachment on multi-walled carbon nanotubes (MWCNTs) in a single step. The effect of several parameters, namely MWCNTs external diameter, rabbit serum concentration, MWCNTs functionalization and pH value, on the IgG attachment yield was evaluated. The dilution of rabbit serum decreased other protein attachment, namely rabbit serum albumin (RSA), while increasing the IgG yield to 100%. The interaction mechanisms between IgG and MWCNTs were evaluated at pH 5.0 to 8.0. The protonation of IgG amino acids indicates that N-term are the most reactive amino acids in the antibody structure. The identification of the N-term reactivity at pH 8.0 allows to indicate a possible orientation of the antibody over the MWCNTs surface, described as “end-on”. Since the amount of RSA attached to MWNT decreased with the increase in serum dilution, the IgG orientation and amine activity was not affected. This orientation demonstrates that the IgG attachment over the surface of the MWCNTs could be an effective strategy to maintain the antigen recognition by the antibody, and to be used for biomedical applications.

Dual-signal output fluorescent aptasensor based on DNA programmability and gold nanoflowers for multiple mycotoxins detection.

Herein, a dual-signal output fluorescent aptamer sensor was constructed for the simultaneous detection of aflatoxin B1 (AFB1) and ochratoxin A (OTA) using the specific recognition ability of aptamers and the programmability of DNA. A functional capture probe (cDNA) was designed with the black hole quenching motif BHQ1 labeled at the 5' end and biotin (bio) labeled at the 3' end. The fluorescent dye Cy3-labeled aflatoxin B1 aptamer (AFB1-Apt) and the carboxyfluorescein FAM-labeled ochratoxin A aptamer (OTA-Apt) were used as two fluorescent probes. The cDNA is anchored to the quenching material gold nanoflowers (AuNFs) by the action of streptavidin (SA) and biotin. Its ends can be complementarily paired with two fluorescent probe bases to form a double-stranded structure. The fluorescence of Cy3 was quenched by AuNFs, and the fluorescence of FAM was quenched by BHQ1 through the fluorescence energy resonance transfer (FRET) effect, forming a fluorescence quenching system. Due to the high affinity of the target and the aptamer, the structure of the aptamer probe changes and detaches from the sensor when AFB1 and OTA are present, resulting in enhanced fluorescence. Under optimal conditions, the linear range of AFB1 was 0.1-100ng/mL (R2 = 0.996), the limit of detection (LOD) was as low as 0.014ng/mL, and the limit of quantification (LOQ) was 0.046ng/mL. The linear range of OTA was 0.1-100ng/mL (R2 = 0.995), the limit of detection (LOD) was as low as 0.027ng/mL, and the limit of quantification (LOQ) was 0.089ng/mL. The sensor had high accuracy in detecting both AFB1 and OTA in real sample analysis. The results of the t test show that there is no significant difference between the results of this study and the high-performance liquid phase (HPLC) method, indicating that the prepared sensor can be used as a potential platform for multiple mycotoxins detection.

An electrochemical biosensor for exosome detection based on covalent organic frameworks conjugated with DNA and horseradish peroxidase

Quantification of trace exosomes in biofluids is helpful for the early diagnosis of cancers. Electrochemical biosensors have attracted special attentions for exosome detection, while the employment of nanoconjugates in the construction of electrochemical biosensors can achieve better performance. So, in this work, we have designed and fabricated HRP-DNA-COF nanoconjugates (HDCs) that involve covalent organic frameworks (COFs) as the scaffold, cholesterol-tagged DNA to recognize exosomes and horseradish peroxidase (HRP) to amplify the signal readout. The successful preparation of HDCs have been verified experimentally, based on which an electrochemical biosensor has been constructed for exosome detection. Attributed to the specific recognition ability and excellent catalytic ability of HDCs, the biosensor achieves good performance to detect exosomes with simplicity and sensitivity in the linear range from 104 to 107 particles/μL. Besides, the strategy proposed in this work to construct COF-based nanoconjugates may promote the wider application of COFs in biomedical research.

Specific recognition and determination of trace phthalic acid esters by molecularly imprinted polymer based on metal organic framework

A novel hybrid material (ZIF-7-NH2@MIP) combining high adsorption capacity of amino-functional zeolitic imidazolate framework and specific recognition ability of dual-template molecular imprinted polymer was synthesized. The prepared ZIF-7-NH2@MIP was characterized by a range of instrumental techniques and combined with high performance liquid chromatography for the detection of four phthalate esters. The limits of detection of the four PAEs were below the maximum residue limit of GB 3838-2002 in China, ranging from 0.04 to 0.08 μg L−1. The recoveries of the three real samples of mineral water, carbonated drinks and pulpy juices spiked at 10 μg L−1 were 88.68–98.58% and the relative standard deviations was 1.19–3.40%. The above results showed that the obtained absorbent exhibited many advantages for extracting analytes in aqueous solution especially complex environment due to the combination of the superior hydrothermal and large specific surface area of the amino-functionalized ZIF-7-NH2 and the specific identification of the dual-template molecular imprinted polymer.

Sensitive Electrochemical Biosensor for Rapid Screening of Tumor Biomarker TP53 Gene Mutation Hotspot.

Rapid and sensitive detection of cancer biomarkers is crucial for cancer screening, early detection, and improving patient survival rate. The present study proposes an electrochemical gene-sensor capable of detecting tumor related TP53 gene mutation hotspots by self-assembly of sulfhydryl ended hairpin DNA probes tagged with methylene blue (MB) onto a gold electrode. By performing a hybridization reaction with the target DNA sequence, the gene-sensor can rearrange the probe’s structure, resulting in significant electrochemical signal differences by differential pulse voltammetry. When the DNA biosensor is hybridized with 1 μM target DNA, the peak current response signal can decrease more than 60%, displaying high sensitivity and specificity for the TP53 gene. The biosensor achieved rapid and sensitive detection of the TP53 gene with a detection limit of 10 nmol L−1, and showed good specific recognition ability for single nucleotide polymorphism (SNP) and base sequence mismatches in the TP53 gene affecting residue 248 of the P53 protein. Moreover, the biosensor demonstrated good reproducibility, repeatability, operational stability, and anti-interference ability for target DNA molecule in the complex system of 50% fetal bovine serum. The proposed biosensor provides a powerful tool for the sensitive and specific detection of TP53 gene mutation hotspot sequences and could be used in clinical samples for early diagnosis and detection of cancer.

Anchoring red blood cell with tetrahedral DNA nanostructure: Electrochemical biosensor for the sensitive signage of circulating tumor DNA

Circulating tumor cells (CTCs), as a type of tumor, have attracted wide attention because of their characteristics of shedding from the primary tumor and spreading to other tissues and organs through peripheral blood. The circulating tumor DNA (ctDNA), the DNA released by CTCs and other tumor cells into the peripheral blood, was considered as a promising detection substance for clinical application. By utilizing the biocompatibility of red blood cells to realize the attachment of tetrahedral DNA (TDN), as well as the specific target recognition ability of TDN to enable efficient recognition of targets, a biocompatible electrochemical biosensor for effective and rapid detection of ctDNA was developed using methylene blue (MB) as the signal probe. The current signal and the logarithm of ctDNA concentration were linearly correlated in the range from 1 fM to 100 pM with the detection limit of 0.66 fM. With high specificity, the TDN-based biosensor can detect ctDNA efficiently in the real biological environment such as serum, which provided a potential opportunity for the early clinical diagnosis.