In Situ Fabrication of Photoluminescent Hydrogen-Bonded Organic Framework-Functionalized Ca (II) Hydrogel Film for the Tetracyclines Visual Sensor and Information Security.

A facilely in situ fabricated hydrogen-bonded organic framework (HOF) hydrogel film with perfect photoluminescent performance was designed for visual sensing of tetracycline antibiotics (TCs) and information security. Luminescent HOF (MA-IPA) was combined with sodium alginate (SA) through hydrogen bonding actions and electrostatic interactions, then cross-linked with Ca2+ ions to form HOF hydrogel film (Ca@MA-IPA@SA). The HOF hydrogel film exhibited exceptional mechanical robustness along with stable blue fluorescence and ultralong green phosphorescence. After exposure to TCs, Ca2+ was combined with TCs to generate a new green fluorescence exciplex (TC-Ca2+) in hydrogel films. Due to fluorescence resonance energy transfer, the fluorescence of MA-IPA was quenched, and the fluorescent color of the HOF hydrogel film was changed from blue to green. This dichromatic fluorescent response is convenient for the visual and rapid detection of TCs. The detection limits of tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC) were 5.1, 7.7, and 32.7 ng mL-1, respectively. Importantly, this hydrogel sensing platform was free of tedious operation and enabled the ultrasensitive and selective detection of TCs within 6 min. It has been successfully applied to TC detection in pork and milk samples. Based on the stable photoluminescence performance of HOF hydrogel films and fluorescent-responsive properties to TCs, two types of anticounterfeiting arrays were fabricated for information encryption and decryption. This work provides a novel approach for on-site detection of TCs and offers valuable insights into information security.

[Development of a multi-residue detection method for 27 typical pharmaceuticals and personal-care products in plants and analysis of their migration patterns in sprouts].

An analytical method based on ultra-performance liquid chromatography-tandem mass spectrometry was developed for the simultaneous determination of 27 pharmaceutical and personal-care product (PPCP) residues in plants. The enrichment and cleanup of PPCPs in plants were achieved using an HLB extraction column, and the separation was performed on a BEH C18 column (100 mm×2.1 mm, 1.7 µm) with 0.1% formic acid water-acetonitrile as the mobile phase via gradient elution. PPCPs were detected with electrospray ionization mass spectrometry in positive-ion multiple-reaction monitoring (MRM) mode. The limits of detection and quantification of the 27 PPCPs in plants were 0.01-0.30 µg/kg and 0.03-0.98 µg/kg, respectively. Good linearities were observed with coefficients of determination (r2) >0.99. The spiked recoveries were between 80.8% and 122.3% with relative standard deviations (RSDs) between 1.0% and 9.9%. The method was subsequently used to study sprouts grown in different concentrations of PPCPs. A total of 10 PPCPs were detected in sprouts grown in medium with a low concentration PPCPs, 13 PPCPs were detected in sprouts grown in medium with a moderate concentration of PPCPs, and 19 PPCPs were detected in sprouts grown in medium with a high concentration of PPCPs. These results showed that plants grown in water bodies contaminated with PPCPs or irrigated with water contaminated with PPCPs absorbed and accumulated these substances and that the amount and type of PPCPs absorbed by plants were closely related to the levels of PPCPs in the external environment. Analysis of the contents of PPCPs in different plant tissues revealed a general distribution of root>stem>leaf. Haemosibutramine showed a tissue distribution of leaf>stem>root, while glibenclamide showed a distribution of root>leaf>stem; these results revealed differences in the distribution of PPCPs in plants. Calculation of the transfer factor (TF) of the PPCPs in plants demonstrated significant differences in the transferability of different PPCPs, with TF=2.34 for haemosibutramine and TF=1.25 for chlorosibutramine. The results showed that among the drugs that migrated in plants, haemonosibutramine and chlorosibutramine had the strongest migration ability in sprouts, followed by nicardipine and chlorpheniramine maleate, and amantadine, N-monodesmethyl sibutramine, carbamazepine and flumequine had the weakest migration ability. Once absorbed, these compounds were transferred to the stems and/or leaves, where they accumulate and cause potential harm by contaminating other plant organs. Therefore, PPCPs such as homosibutramine and chlorosibutramine, which easily migrate in plants, should be given extra attention in future studies. The method is simple in pre-treatment, sensitive and accurate, and can be widely applied to the detection of PPCP residues in plant samples.

"Three-in-one" nanohybrids as synergistic nanozymes assisted with exonuclease I amplification to enhance colorimetric aptasensor for ultrasensitive detection of kanamycin.

Kanamycin (KAN) residues in animal-derived food can cause serious threats to human health. Herein, a colorimetric aptasensor was described using "three-in-one" nanohybrids (hemin@Fe-MIL-88NH2/PtNP) as synergistic nanozymes assisted with the exonuclease I (Exo I) signal amplification for the ultrasensitive detection of KAN. In the presence of KAN and Exo I, the KAN aptamer (APT) was specifically bound to KAN, and the remaining APT complementary strand (cDNA1) captured hemin@Fe-MIL-88NH2/PtNP labeled with the cDNA1 complementary strand (cDNA2). Due to the synergistic effect of hemin, Fe-MIL-88NH2 and platinum nanoparticles (PtNPs), hemin@Fe-MIL-88NH2/PtNP exhibited superior catalytic performance and could efficiently catalyze the 3,3',5,5'-tetramethylbenzidine (TMB)-H2O2 system for signal development. Moreover, Exo I could digest APT and release KAN into a new cycle for signal amplification. Based on multiple signal amplification effects, our proposed aptasensor achieved a wide detection range from 0.01 to 100 ng mL-1 with a low detection limit of 2 pg mL-1. This assay also successfully detected KAN-added milk and shrimp samples with added recovery ranges of 93.58%-106.08% and relative standard deviations (RSDs) of 2.20%-5.50%. The aptasensor enabled ultrasensitive, specific, and fast detection of KAN, and exhibited promising applications in the efficient detection of food pollutants.

Polystyrene nanofibers as an effective sorbent for the adsorption of clonazepam: kinetic and thermodynamic studies.

Polystyrene (PS) electrospun nanofibers were prepared via electrospinning for the adsorption of clonazepam from aqueous solution. The adsorption conditions such as adsorption time, solution pH and the amount of adsorbent were optimized. The adsorption kinetics and thermodynamic properties of clonazepam on PS nanofibers were studied under optimized conditions. The pseudo-second-order kinetic model can fit well the adsorption process of clonazepam on polystyrene nanofibers, indicating that the diffusion process in the fiber is the rate-limiting step of the adsorption process. The adsorption equilibrium data are in accordance with the Freundlich isotherm model, and the maximum adsorption capacity is 3.2 mg g-1. Thermodynamic studies revealed that the adsorption process is endothermic and spontaneous in nature. It was suggested that PS electrospun nanofibers have good potential for the separation and purification of clonazepam from a water-soluble matrix as a novel effective adsorbent material.

Label-free differentiation and quantification of ricin, abrin from their agglutinin biotoxins by surface plasmon resonance.

Here we describe an affinity molecule-directed surface plasmon resonance (SPR) immunosensor for a label-free, differentiation and quantification of ricin and abrin from their structural highly like agglutinin biotoxins. By an introduction of protein G as the affinity capturing molecule, we fulfilled a complete strategy contains (i) screening monoclonal antibodies to be paired in a sandwiched format, (ii) differentiate quantification from the agglutinin, (iii) ascertain of active from inactive biotoxin, and (iv) structural identification of captured biotoxins on a single chip. By the aid of an enrichment step from immunomagnetic beads, we could accurately measure ricin or abrin with a concentration lowered to 0.6 ng/mL (10 pM) in different complex matrices such as stevia, protein powder, and human plasma, with linear ranges of two or three orders of magnitude, and satisfied recovery. We then differentially quantified the mixed crude extracts from castor beans and jequirity peas, and real samples from the fourth OPCW biotoxin exercise to prove the practical availability. We further provided a SPR-mass spectrometric evidence directly obtained from Protein G affinity chip via a noncovalent molecule surface for the first time for definitely structural identification for crude extracts.

Effects of low-concentration glyphosate and aminomethyl phosphonic acid on zebrafish embryo development.

Glyphosate (GLY) is the most widely used broad-spectrum, non-selective herbicide in the world, whose main degradation product is aminomethyl phosphonic acid (AMPA). Because of long-term and large-scale use, residual GLY and AMPA in the environment pose great environmental and human health threats. The purpose of this study is to evaluate the effects and mechanism of residual low-concentrations of GLY and AMPA in the environment on the development of zebrafish embryos. Zebrafish embryos were exposed to 0, 1, 10, 100, and 700 ng·mL-1 GLY and AMPA for 72 h (from 2 to 74 h post-fertilization). With increasing exposure dose, heart rates of both embryos and larvae showed a rising trend and obvious arrhythmia appeared. Defects in cardiac development and function of zebrafish juveniles may be related to altered transcription levels of cardiac development genes (TBX5, NKX2.5, BMP4) and apoptosis genes (Bcl-2, Bax). In addition, pericardial edema and bone deformation of zebrafish embryos may be caused by inhibition of Na+/K+-ATPase and Ca2+-ATPase after exposure to GLY and AMPA. The present results demonstrated that at typical environmental residual concentrations of GLY and AMPA had similar developmental toxicity in zebrafish embryos.

Genotoxicity of chloroacetamide herbicides and their metabolites in vitro and in vivo.

The toxicity of chloroacetamide herbicide in embryo development remains unclear. Acetochlor (AC) is a chloroacetamide that metabolizes into 2­ethyl­6­methyl-2-chloroacetanilide (CMEPA) and 6­ethyl­o­toluidine (MEA). The present study determined the potential effect of AC and its metabolites on embryo development. Both HepG2 cells and zebrafish embryos were exposed to AC, CMEPA and MEA in the presence or absence of co­treatment with anti­reactive oxygen species (ROS) reagent N­acetylcysteine. The generation of ROS, levels of superoxide dismutase (SOD) and glutathione (GSH) in HepG2 cells and lactate dehydrogenase (LDH) leakage from HepG2 cells were investigated. The effects of AC, CMEPA and MEA on DNA breakage, MAPK/ERK pathway activity, viability and apoptosis of HepG2 cells were examined by comet assay, western blotting, MTT assay and flow cytometry, respectively. Levels of LDH, SOD and GSH in zebrafish embryos exposed to AC, CMEPA and MEA were measured. The hatching and survival rates of zebrafish embryos exposed to AC, CMEPA and MEA, were determined, and apoptosis of hatched fish was investigated using acridine orange staining. The present data showed AC, CMEPA and MEA induced generation of ROS and decreased levels of SOD and GSH in HepG2 cells, which in turn promoted DNA breakage and LDH leakage from cells, ultimately inhibiting cell viability and inducing apoptosis, as well as phosphorylation of JNK and P38. However, co­treatment with N­acetylcysteine alleviated the pro­apoptosis effect of AC and its metabolites. Moreover, exposure to AC, CMEPA and MEA lead to toxicity of zebrafish embryos with decreased SOD and GSH and increased LDH levels and cell apoptosis, ultimately decreasing the hatching and survival rates of zebrafish, all of which was attenuated by treatment with N­acetylcysteine. Therefore, AC and its metabolites (CMEPA and MEA) showed cytotoxicity and embryo development toxicity.

Determination of gamithromycin residues in eggs, milk and edible tissue of food-producing animals by solid phase extraction combined with ultrahigh-performance liquid chromatography-tandem mass spectrometry.

A high throughput method was developed and validated for the quantitation of gamithromycin residues in eggs, milk and animal tissues (leg muscle, kidney, liver and fat) of different species and genera. This was undertaken using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The samples were extracted with acetonitrile and purified using an Oasis MCX solid phase extraction cartridge. Subsequently, a C18 column was used for chromatographic separation using acetonitrile and 0.1% formic acid as the mobile phase. LC-MS/MS in positive ESI and multiple reaction monitoring mode with gamithromycin-D4 as the internal standard was used for detection and quantification of gamithromycin. The method was successfully calibrated in the range of 1.0-200 µg/kg. The limit of detection (LOD) and limit of quantification (LOQ) for gamithromycin was 0.30-0.40 µg/kg and 0.80 - 1.0 µg/kg, respectively. The average recoveries of the analyte fortified at three levels ranged from 84.2% to 115.9%, with a relative standard deviation <10%. The proposed method has been successfully used to monitor real samples, and shown to be sensitive, rapid, and convenient. Hence, this method could be used for regulatory purposes to screen for the presence of gamithromycin residues in eggs, milk and target tissues.

Cyanuric chloride-imidazole dendrimer functionalized nanoparticles as an adsorbent for magnetic solid phase extraction of quaternary ammonium compounds from fruit and vegetable puree based infant foods.

A novel magnetic solid-phase extraction (MSPE) material (Fe3O4@SiO2-NH2-G2) had been prepared and employed for adsorption and analysis of seven quaternary ammonium compounds (QACs) in infant fruit and vegetable products coupled with high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). In this paper, Fe3O4@SiO2-NH2-G2 was synthesized based on Fe3O4@SiO2-NH2 and dendrimer (G2) consisting of cyanuric chloride and imidazole. The morphology, configuration and magnetic behavior of the magnetic material were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). Critical parameters affecting extraction efficiency, such as the adsorbent amount, sample pH, extraction time, the type of eluent, and desorption time, were optimized. The proposed method provided good linearity with the correlation coefficients (R2) of 0.9992-0.9999, low limits of detection (LODs) (0.05-0.50 µg kg-1) and limits of quantitation (LOQs) (0.20-2.00 µg kg-1). The satisfactory method recoveries in three spiked infant fruit and vegetable products samples were between 80.12% and 101.35% with the relative standard deviations (RSDs) less than 12.04%. In summary, the established method was an effective sample preparation method and showed good prospect for the analysis of QACs in complex matrices.

Determination of folic acid by capillary zone electrophoresis with indirect chemiluminescence detection.

A capillary electrophoresis method with on-line inhibited chemiluminescence (CL) detection was first used to determine folic acid (FA). This method was established based on the quenching effect of FA on the CL reaction of luminol with a Ag(iii) complex in alkaline medium. The separation was conducted with a 20.0 mM sodium borate buffer containing 1.0 mmol L-1 luminol. Under optimized conditions, FA was baseline separated and detected in less than 10 min. The limit of detection of FA was 1.3 mg L-1, with a linear range of 5.0-150.0 mg L-1 (r = 0.9953). The RSD value was 2.8% for intra-day precision and 5.4% inter-day precision. The recoveries of the standard addition of tablets and human urine ranged from 90.3% to 107.5% and from 82.0 to 105.7%, respectively. The proposed method was successfully applied to determine FA contents in commercial pharmaceutical tablets and human urine samples. Results suggested that this method was simple and robust.

Rapid and sensitive detection of prostate-specific antigen via label-free frequency shift Raman of sensing graphene.

The sensitive and accurate detection of cancer biomarkers is critically important to early clinical diagnosis, disease monitoring, and successful cancer treatment. Here, we first demonstrate an aptamer-based frequency shift Raman approach via sensing of graphene. This biosensor allows the rapid, sensitive, and label-free detection of the acknowledged protein cancer biomarker, prostate-specific antigen (PSA). Monolayer graphene is employed as the Raman substrate, which is highly sensitive to its electronic structure and interface properties. The PSA aptamer can be adsorbed strongly on the surface of substrates through π-π stacking interactions. The vibrational frequency of the G peak of graphene shifted upon the specific binding between the PSA and its aptamer. The corresponding frequency shifts of the G peak are directly correlated with PSA concentrations. The limit of detection is as low as 0.01 ng/mL, with a wide linear range from 0.05 ng/mL to 25 ng/mL. The analytic samples can be detected directly without any extensive preparation and label process. The whole detection is completed in only 30 min. Furthermore, excellent recoveries are acquired to validate the feasibility of this assay in human serum samples. The proposed technology could provide a selective, versatile, and user-friendly strategy for the early detection of cancer biomarkers.

Determination of monoamine neurotransmitters and metabolites by high-performance liquid chromatography based on Ag(III) complex chemiluminescence detection.

A novel, simple and efficient chemiluminescence system has been developed for the determination of monoamine neurotransmitters and metabolites. By using the Ag (III)-luminol chemiluminescence system as a detector, a high performance liquid chromatography chemiluminescence method (HPLC-CL) was established and used to detect seven monoamine neurotransmitters. Under the optimized conditions, the detection limits (3S/N) of epinephrine (E), levodopa (l-DOPA), dopamine (DA), serotonin (5-HT), 3-methoxy-4-hydroxyphenylglycol (MHPG), 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxypentylacetic acid (5-HIAA) were 20.0 µg dm-3,15.0 µg dm-3, 15.0 µg dm-3, 8.0 µg dm-3, 2.0 µg dm-3, 2.0 µg dm-3 and 3.0 µg dm-3, respectively. Moreover, they were well within the linear range of 50-1000 µg dm-3, 50-1000 µg dm-3, 50-1000 µg dm-3, 25-1000 µg dm-3, 5-25 µg dm-3, 5-25 µg dm-3 and 10-30 µg dm-3, respectively. The average recovery varied between 84.82% and 110.4%. The method has the attributes of simplicity, high sensitivity, and high efficiency. The sensitization and inhibition mechanisms for luminol-[Ag(HIO6)2]5-- analytes CL system were proposed by CL spectra and free-radical capture experiment.

Simultaneous determination of 11 antiseptic ingredients in surface water based on polypyrrole decorated magnetic nanoparticles.

With the emergence and spread of coronavirus COVID-19, the use of personal cleansing, medical and household disinfectant products have increased significantly. In this work, a new magnetic solid-phase extraction (MSPE) method for the determination of 11 antiseptic ingredients in surface water by high performance liquid chromatography-mass spectrometry (HPLC-MS/MS) for 6 months based on Fe3O4@PPy magnetic nanoparticles (MNPs) was established. The MSPE method possessed the advantages of simple processing, little time consumption and less organic solvent consumption, and the MNPs could be reused several times. The analytical parameters influencing the extraction efficiency, such as sample pH, amount of MNPs and extraction time, were optimized in detail. It was indicated that the method had satisfactory linearities in the range of 0.50 to 1000.0 µg L-1 with the correlation coefficients (r) higher than 0.9996. Additionally, satisfactory spiked recoveries were achieved in the range of 80.21-107.33% with relative standard deviations (RSDs) from 1.98% to 8.05%. The limits of detection (LODs) and limits of quantitation (LOQs) were in the range of 0.20 to 2.0 µg L-1 and 0.50 to 5.0 µg L-1. Therefore, the developed MSPE-HPLC-MS/MS method has high selectivity and stability, and satisfactory quantitative capability for the antiseptic ingredients in surface water. Furthermore, this method can provide relevant technical support for the development of surface water standards.

An untargeted and pseudotargeted metabolomic combination approach to identify differential markers to distinguish live from dead pork meat by liquid chromatography-mass spectrometry.

An untargeted and pseudotargeted metabolomic combination approach was developed to identify reliable and stable differential markers which can distinguish between pork meat from live pigs conventionally butchered and pork meat from dead pigs butchered immediately after death from diseases or other abnormalities. In this study, 24 differential metabolites of interest were screened by the UHPLC-Triple-TOF-MS-based untargeted metabolomic method, and 14 differential markers were detected by the UHPLC-QTRAP-MS-based pseudotargeted metabolomic method after performing statistical analysis to remove false-positive differential metabolites. Among the possible differential markers identified using the Metlin database and references were carnosine, l-carnitine, l-histidine, N-acetylhistidine, acetylcholine, l-acetylcarnitine and two phosphatidylcholines. The results of the principal component analysis (PCA) and the hierarchical clustering analysis (HCA) indicate that 14 differential markers could be potentially used to distinguish live and dead pork meat. This reliable and stable approach not only could detect the unknown differential markers, but also accurately quantify them.

Simultaneous Determination of Five Hormones in Milk by Automated Online Solid-Phase Extraction Coupled to High-Performance Liquid Chromatography.

BACKGROUND: Many hormones show the effects of protein assimilation and growth promotion, and they are frequently used as veterinary drugs in livestock, which has harmful effects on human health. It is necessary to determine their contamination level in animal-derived food, especially in milk. OBJECTIVE: In this study, a detailed procedure is described for an automated online solid-phase extraction (SPE)-HPLC method capable of detecting five hormones (i.e., estriol, prednisone acetate, hydrocortisone, diethylstilbestrol, and estrone) in cow milk. METHODS: The corresponding milk samples were precipitated by addition of acetonitrile and then purified as well as enriched by a polar-enhanced polymer (PEP) online SPE column. The supernatants were directly injected into the online SPE-HPLC system using methanol-water as the mobile phase mixture. RESULTS: The linearity range of the method was 0.1-25 µg/mL for prednisone acetate, hydrocortisone, and diethylstilbestrol, 0.2-25 µg/mL for estriol, and 0.5-25 µg/mL for estrone, with correlation coefficients (r) ranging from 0.9994 to 0.9996. The recovery rates determined at three concentration levels for the five compounds were in the range of 70.82-112.90%. LODs of estriol, prednisone acetate, hydrocortisone, diethylstilbestrol, and estrone were 0.023, 0.005, 0.006, 0.004, and 0.054 µg/mL, respectively. CONCLUSIONS: This automated online SPE-HPLC method was both effective and reliable in the simultaneous measurement of five hormones, and the method was successfully applied to the detection of five hormone species in milk. HIGHLIGHTS: An automated online SPE-HPLC method has been developed for the analysis of five hormones in cow milk. Online SPE proved to be a powerful technique for determining five hormones simultaneously. This method ensured simple sample pretreatment and less operation time. The established method was successfully applied to the analysis of five hormone species in milk.

Determination of Bisphenol A by High-Performance Liquid Chromatography Based on Graphene Magnetic Dispersion Solid Phase Extraction.

Bisphenol A (BPA), as one of the environmental endocrine disruptors, is extensively existing and threatening to human health. To evaluate the environmental exposure level and protect human from the hazard of BPA, a precise and sensitive method is established. In this work, Graphene@ Fe3O4 (G@Fe3O4) is prepared by chemical coprecipitation method as magnetic dispersion solid phase extraction (MDSPE) material. The rapid and specific detection method of BPA is carried out by high-performance liquid chromatography (HPLC). Properties of G@Fe3O4 are identified by the fourier infrared spectrum and scanning electron microscopy. Conditions of solid phase extraction are optimized. Under the optimal extraction conditions, G@Fe3O4 has perfect enrichment effect on BPA. There is a good linear relationship in the range of 5.0~1000.0 µg/L with the correlation coefficient of 0.9997. The detection limit is 0.1 µg/L. This method is applied to water samples successfully, and recoveries of BPA are between 88.19% and 99.56% (RSDs < 3.00%). G@Fe3O4 was synthesized, which was used to extract BPA in water samples before HPLC analysis, and has shown perfect extraction ability toward BPA, which indicates that the determination method of BPA by HPLC based on graphene MDSPE is faster and more precise.

Magnetic solid-phase extraction of four ß-lactams using polypyrrole-coated magnetic nanoparticles from water samples by micellar electrokinetic capillary chromatography analysis.

In the present research, the application of a polypyrrole coating on Fe3O4 magnetic nanoparticles (PPy/Fe3O4 MNPs) as a sorbent was confirmed. The synthesized magnetic composites were characterized by TEM, FTIR spectroscopy, and XRD. Four ß-lactams (oxacillin (OXA), cloxacillin (CLOX), dicloxacillin (DIC), and flucloxacillin (FLU)) were selected as analytes for the experiment. The extracted ß-lactams were determined by micellar electrokinetic capillary chromatography-diode array detector (MEKC-DAD). The crucial parameters influencing the extraction efficiency and separation were studied and optimized. Under the optimal conditions, the limits of detection are 1.0 µg L-1 for OXA, CLOX, FLU, and 0.8 µg L-1 for DIC. The calibration curves are linear in the range of 2.5-200.0 µg L-1. The proposed method was applied for the determination of the ß-lactams in water samples with satisfactory results. The intra-day relative standard deviations and the inter-day relative standard deviations range from 1.09% to 4.58% and from 2.95% to 7.80%, respectively. It can be concluded that this method is sensitive, convenient, and feasible for the determination of the ß-lactams in water samples.

A zirconium-porphyrin MOF-based ratiometric fluorescent biosensor for rapid and ultrasensitive detection of chloramphenicol.

An ultrasensitive and rapid detection of trace antibiotics is imperative for food safety and public health. Herein, we present a ratiometric fluorescent sensing strategy based on an aptamer labeled with a fluorescent dye and a highly stable zirconium-porphyrin MOF (PCN-222) as a fluorescence quencher for the high-efficiency detection of chloramphenicol (CAP). PCN-222 exhibits a strong adsorption ability toward the dye-labeled aptamer through π-π stacking, electrostatic, hydrogen bond, and coordination interactions. Experimental and simulation studies confirm that PCN-222 demonstrates a high quenching efficiency via fluorescence resonance energy transfer (FRET) and photoinduced electron transfer (PET) processes. In the presence of CAP, dye-labeled aptamers are released from the PCN-222 surface, resulting in the recovery of fluorescence. This proposed biosensor allows the complete detection of CAP within 26 min. For ratiometric measurement, its detection limit is as low as 0.08 pg mL-1 with a wide detection range from 0.1 pg mL-1 to 10 ng mL-1. It is successfully applied to analyze CAP in milk and shrimp samples, and its results are consistent with those of the commercial ELISA kit. This biosensor not only enables the rapid, ultrasensitive, and highly specific detection of CAP but also reveals excellent universality and multiplexed analysis performance.

Determination of higenamine in multi-matrix by gas chromatography-mass spectrometry combined with derivatization technology.

Higenamine (HG), a cardioactive component of some foods and medicines, has been listed in the doping category by the International Olympic Committee, which may lead to misuse by athletes. We report the development of a gas chromatography-mass spectrometry (GC-MS) method for determination of HG in various matrix samples (biological samples, different forms of Chinese patent medicine, Chinese herbal medicine) based on acylation derivatization of HG by heptafluorobutyric anhydride. Under optimal conditions, the linearity of HG in the range of 5-200 ng mL-1 was acceptable (R2 > 0.999), and the limit of detection (LOD) and limit of quantitation (LOQ) for HG was 1.52 ng mL-1 and 5 ng mL-1, respectively. Low, medium, and high concentrations (25, 100 and 160 ng mL-1) of HG were added to plasma, urine, oral liquid, capsule, watered bolus, honeyed bolus and Chinese herbal medicine samples, with recovery ranging from 82.70 to 109.80%, intra-day and inter-day precisions were both less than 3.39%. The results indicated that the method had sufficient sensitivity for analysis of biological samples, and Chinese patent and herbal medicine.

Roles of mtDNA damage and disordered Ca2+ homeostasis in the joint toxicities of cadmium and BDE209.

Cadmium, a typical heavy metal, causes serious toxicities on many organs and tissues. As the last partially controlled class of polybrominated diphenyl ethers (PBDEs), BDE209 can also induce various health issues. Although apoptosis mediated by mitochondria has been known to be a key player in inducing toxicities by cadmium, the detailed mechanisms are incompletely understood. Moreover, co-existence of cadmium and PBDEs has been found in various environment context and human body. However, studies on the joint toxicity of cadmium and PBDEs are still limited with largely unknown mechanisms. In the present study, we investigated the adverse effects and mechanisms of single or combined treatment of CdCl2 and BDE209 on hepatocytes. We observed that apoptosis were significantly induced by CdCl2, and the combined treatment of CdCl2 and BDE209 greatly promoted the progression of apoptosis. BDE209 induced mild apoptosis. Mitochondria was the pivot of several mechanisms to induce apoptosis, including ROS production, decreased mitochondrial membrane potential (MMP), mtDNA damage and disordered calcium (Ca2+) homeostasis. However, we found that mtDNA damage and disordered Ca2+ homeostasis were the main mechanisms for CdCl2-induced apoptosis while ROS production played important roles in BDE209-induced apoptosis. Less mtDNA damage occurred in BDE209-treated cells. In the cells with combined treatment, CdCl2 and BDE209 exhibited a complementary pattern for the underlying mechanisms of apoptosis, leading to the joint toxicities, in which CdCl2 showed more contributions. In a conclusion, our results demonstrated that combined exposure to cadmium and BDE209 causes joint adverse effects on hepatocytes through diverse mechanisms as mediated by mitochondria.