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The 25Mg(p, γ )26Al reaction plays an important role in the study of cosmic 1.809 MeV γ -ray as a signature of ongoing nucleosynthesis in the Galaxy. At astrophysical temperature around 0.1 GK, the 25Mg(p, γ )26Al reaction rates are dominated by the 92 keV resonance capture process. We report a precise measurement of the 92 keV 25Mg(p, γ )26Al resonance in the day-one experiment at Jinping Underground Nuclear Astrophysics experiment (JUNA) facility in the China Jinping Underground Laboratory (CJPL). The resonance strength and ground state feeding factor are determined to be 3.8 ± 0.3 ×10−10 eV and 0.66 ± 0.04 , respectively. The results are in agreement with those reported in the previous direct underground measurement within uncertainty, but with significantly reduced uncertainties. Consequently, we recommend new 25Mg(p, γ )26Al reaction rates which are by a factor of 2.4 larger than those adopted in REACLIB database at the temperature around 0.1 GK. The new results indicate higher production rates of 26gAl and the cosmic 1.809 MeV γ -rays. The implication of the new rates for the understanding of other astrophysical situations is also discussed.

The origin of calcium production in the first stars (Pop III stars), which formed out of the primordial matter of the Big Bang, and their fates, remain most fascinating mysteries in astrophysics. Advanced nuclear burning and supernovae were thought to be the dominant source of the Ca production seen in all stars. Here we report on a qualitatively different path to Ca production through break-out from the "warm" carbon-nitrogen-oxygen (CNO) cycle. We extend direct measurement of the $^{19}$F($p$, $\gamma$)$^{20}$Ne break-out reaction down to an unprecedentedly low energy point of 186 keV and discover a key resonance at 225 keV. In the domain of astrophysical interest, at around 0.1 giga kelvin, this thermonuclear $^{19}$F($p$,$\gamma$)$^{20}$Ne rate is up to a factor of 7.4 larger than the previous recommended rate. Our stellar models show a stronger break-out during stellar hydrogen burning than thought before, and may reveal the nature of Ca production in Pop III stars imprinted on the oldest known ultra-iron poor star, SMSS0313-6708. This result from the China Jinping Underground Laboratory, the deepest laboratory in the world, offering an environment with extremely low cosmic-ray induced background, has far-reaching implications on our understanding of how the first stars evolve and die. Our rate showcases the impact that faint Pop III star supernovae can have on the nucleosynthesis observed in the oldest known stars and first galaxies, key mission targets of the James Webb Space Telescope., Comment: 32 pages, 8 figures, 6 tables

Nine fluorine targets of various types were developed for the 19F( p , α )16O experiment to be performed at the Jinping Underground Nuclear Astrophysics Experiment (JUNA), China. Two targets were produced by evaporating CaF2 on Ta backings: one was produced by sputtering MgF2 on the Cr+Fe backings, and six were produced by implanting 20–80 keV 19F ions into pure Fe and Cu backings. Thin Cr protective layers were covered over these targets. We assessed each target’s stability by monitoring the γ -ray yields of the 19F( p , α γ )16O reaction over the well-known 340 keV resonance. Our results indicate that the traditional evaporated and sputtered targets exhibit 0.6%–6% deterioration (or 19F material loss) per Coulomb, while the implanted targets exhibit relatively small deterioration due to the proton beam bombardment. For the optimum target #8, the 19F target material loss is only approximately 0.05% per Coulomb proton beam bombardment, and such target is much more stable than the traditional targets. The fluorine depth distribution of the implanted target #8 was precisely analyzed by the atom probe tomography (APT) technique. The obtained depth distribution can well reproduce the experimental γ -ray yield curve. Furthermore, as test experiment, the 19F( p , α γ )16O cross section was measured with the implanted target #8 in a center-of-mass energy region of E c.m. = 174–358 keV, which is consistent with the previous results. In conclusion, traditional fluorine targets produced with the evaporation and sputtering techniques are not suitable for the high-current experiment even with a protective layer. For the upcoming high-current JUNA experiment, this work offers an optimum target scheme: first, implanting 19F ions into the pure Fe backings with an implantation energy of 40 keV, and then sputtering a 50 nm thick Cr layer to further prevent the fluorine material loss.

Proposed mechanisms for the production of calcium in the first stars (population III stars)-primordial stars that formed out of the matter of the Big Bang-are at odds with observations

Osimertinib is a third‐generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR‐TKI) for lung adenocarcinoma (LUAD) harboring activating mutations, but patients ultimately develop acquired resistance. Circular RNAs are involved in EGFR‐TKI resistance, while the role of hsa_circ_0005576 in the osimertinib resistance of LUAD remains unknown. In this study, we demonstrated that hsa_circ_0005576 could facilitate osimertinib‐resistant LUAD cells. Briefly, knockdown of hsa_circ_0005576 not only suppressed the proliferation and promoted the apoptosis of resistant LUAD cells, but also increased their sensitivity to osimertinib. Mechanistically, hsa_circ_0005576, serving as an miRNA sponge, could directly interact with miR‐512‐5p and subsequently upregulate the miR‐512‐5p‐targeted insulin‐like growth factor 1 receptor. Rescue assays indicated that miR‐512‐5p inhibition could reverse the effects of hsa_circ_0005576 knockdown in LUAD cells resistant to osimertinib. Overall, our study revealed that hsa_circ_0005576 regulates proliferation and apoptosis through miR‐512‐5p/IGF1R signaling, which contributes further to the resistance of LUAD cells to osimertinib. In addition, this study provides a novel insight into the mechanisms underlying osimertinib resistance of LUAD., This study revealed that hsa_circ_0005576 regulates proliferation and apoptosis through miR‐512‐5p/IGF1R signaling, which contributes further to the resistance of LUAD cells to osimertinib. In addition, it provides a novel insight into the mechanism underlying osimertinib resistance of LUAD.

BACKGROUND: Emulsification is important for food quality and processing functionality. Most emulsification occurs under high‐fat conditions that eventually cause health concerns. Protein emulsifiers also have drawbacks such as lower dispersity. This study considered the effects of different high‐speed shear homogenization (HSH) speeds on the emulsifying and structural properties of myofibrillar proteins (MPs) under low‐fat conditions. RESULTS: High‐speed shear homogenization significantly increased the emulsifying activity and emulsifying stability of MPs at lower speeds (8000 to 14 500 rpm). The primary structure of MP was not altered significantly by HSH, whereas its secondary, tertiary, and quaternary structures were changed. Particle size decreased first and then increased significantly, and reached a minimum when the HSH speed was 14 500 rpm. The absolute zeta potential values increased significantly and the dendritic fibrous structure of sample was destroyed when the speed exceeded 14 500 rpm. High‐speed shear homogenization (14 500 rpm) decreased the particle size and unfolded the protein, which improved the emulsifying properties of MPs. Excessive HSH speeds (20 500 rpm or higher) caused an aggregation of MP molecules, which was not conducive to improving their emulsifying properties. CONCLUSION: Optimal HSH speed was achieved at 14 500 rpm to modify MPs' emulsifying and structural properties under low‐fatconditions. © 2019 Society of Chemical Industry

Effects of high-speed shear homogenization on the properties of myofibrillar protein (MP) and low-fat mixed gel were studied. The morphological structure, secondary structure, surface hydrophobicity, sulfhydryl groups and zeta potential of mixed gels were also measured. Under our experimental conditions, 14,500 rpm was the optimum speed to facilitate the gel strength, water holding capacity and G’ values of mixed gel. The fat particles evenly distributed in mixed gel and MP molecules formed a uniform network structure were the important reasons for shear homogenization treatment enhancing the properties of mixed gel. More β-sheet structure content was the underlying cause of shearing treatment to enhanced the mixed gel properties. The changes of zeta potential indicated that MP molecules were difficult to form gel by excessive shear homogenization treatment (higher than 14,500 rpm). Therefore, 14,500 rpm was the optimum shear homogenization speed to modify the structure properties, so as to achieve better gel properties of MP-fat mixed gel.

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The cosmic 1.809 MeV γ-ray emitted by the radioactive nucleus 26Al in the Galaxy is one of the key observation targets of the γ-ray astronomy. The 26Al is mainly produced by the 25Mg(p,γ)26Al reaction in the stellar Mg-Al reaction cycle. At the astrophysical relevant temperatures, the reaction rates of 25Mg(p,γ)26Al are dominated by several narrow resonances at low energy. This work reports a measurement of the low energy 25Mg(p,γ)26Al resonances at Jinping Underground Nuclear Astrophysics experimental facility (JUNA) in the China Jinping Underground Laboratory (CJPL).

22Ne(α,n)25Mg is one of the main neutron sources of the s process. 22Ne is produced by the 14N(α, γ)18F(β+)18O(α, γ)22Ne reaction chain in the helium burning, thus, the production rate of 22Ne is dominated by 14N(α,γ)18F and 18O(α,γ)22Ne. At the astrophysical relevant temperatures, the 18O(α,γ)22Ne reaction rates are determined by several low-energy resonances. In this work, the 18O(α,γ)22Ne reaction was measured at the 400 kV accelerator of Jinping Underground Nuclear Astrophysics experiment (JUNA). The γ-ray yields of the resonances between 470 to 770 keV were obtained.

A point of care testing (POCT) colorimetric aptasensor was developed to detect streptomycin (STR) using porous SiO 2 micro beads (pore size of 200 nm) −enzyme linked polymer (PowerVision™, PV) probes and exonuclease-assisted target recycling for signal amplification. The probe was fabricated by single- stranded DNA binding protein labelled SiO 2 micro particles (P-SiO 2 -SSB) as capture probes and Au NPs & aptamer (Apt) co-immobilized on PV (Apt-Au-PV) as nanotracer. In the presence of STR and exonuclease I (Exo I), the nanotracer would combine with STR to form the complex (STR/Apt-Au-PV). Hereafter, Exo I further digest the aptamer on STR/Apt-Au-PV, then STR was released again to participate new cycling, the approach lead to generate more nanotracers into supernatant to improve the sensitivity. Moreover, the dendrimer PV which contains large quantities of HRPs can efficiently catalyzed H 2 O 2 -TMB (3,3′,5,5′- tetramethylbenzidine) system for color development and the results can observed by the naked eye. Due to the excellent multiple signal amplification effects for porous SiO 2 micro particles to label more nanotracer, PV and exonuclease-assisted target recycling, the aptasensor exhibit a low detection limit with 1 pg mL −1 (S/N = 3). In addition, the developed method might provide a prospect assay for food tests at point of care.

The effects of three polysaccharides on the textural properties and microstructure of myofibrillar protein (MP) gels were studied. The gel strength and rheological properties of composite MP gels were significantly improved with insoluble dietary fibre (DF) and modified starch (MS) addition, while konjac glucomannan (KG) had limited effects at 1% addition. The SEM images indicated that moisture extrusion formed moisture channels and deteriorated the aggregation of MP gel networks during the thermal process. The polysaccharides stabilized moisture and reduced the appearance of moisture channels in the gel network, thereby promoting the formation of compact and integral gel networks. The MP-polysaccharide mixture is a thermally incompatible system and presented two main forms after the thermal process: 1) the “trapped” structure and 2) the “interpenetrated” structure. In the “trapped” structure, the MP was the dominant structure of the composite gel network. In the “interpenetrated” structure, the continuous polysaccharide hydrogel substantially hindered the aggregation of MP gel networks. Principal component analysis showed that the phase behaviour and moisture stability of polysaccharides significantly influenced the textural quality and microstructure of composite MP gelation. The study indicated that polysaccharides that contribute to moisture stability and form a “trapped structure” (phase behaviour) are ideal fat replacements for improving composite gel properties, especially DF.

Herein, a promising colorimetric strategy for small molecule detection was developed based on one novel magnetic single-stranded DNA binding protein (SSB)-linked composite probe. Firstly, a magnetic probe was synthesized by labeling SSB on gold magnetic particles (Au MNPs-SSB) and detection probe by co-immobilizing aptamer (Apt) and horseradish peroxidase (HRP) on the core-shell SiO 2 @Au nanoparticles (Apt-SiO 2 @Au-HRP); furthermore, Au MNPs-SSB was bound with Apt-SiO 2 @Au-HRP to construct a composite probe relied on the specific affinity between SSB and free aptamer. When the target, with chloramphenicol (CAP) as model, was introduced into the reaction system, the formation of the target-Apt-SiO 2 @Au-HRP complex can release from its parent probe to supernatant after magnetic separation because SSB can’t bind target-aptamer complex. The target-Apt-SiO 2 @Au-HRP complex in supernatant could efficiently catalyze 3,3′,5,5′-tetramethylbenzidine(TMB)-H 2 O 2 system for the color development. Under the optimized reaction conditions, the linear range was from 0.05 to100 ng mL −1 with a low detection limit of 0.02 ng mL −1 for CAP. Moreover, the aptamer assay was employed to detect CAP in milk and the results were consistence with those from ELISA. In addition, the assay can be easily extended to other small molecules detection when changing the corresponding aptamer on the detection probe.

In this study, a novel three dimensional (3D) M × N type aptamer-functionalized solid-phase micro extraction (SPME) fibers array (M represents the number of targets; N represents the number of samples) was developed for selective enrichment of multiplex antibiotic residues from milk samples, with three chloramphenicols (CAPs) as models. First, gold nanoparticles (AuNPs) were electrodeposited on a gold wire (Φ = 0.2 mm), which was wound around a conductive indium tin oxide (ITO) glassy fiber. Then, the fiber was immersed into thiol-functionalized aptamer solution, which could specifically recognize three CAPs, including chloramphenicol (CAP), thiamphenicol (TAP) and florfenicol (FF). The aptamer can be covalently immobilized on AuNPs through Au–S bonds. Thus, a 3D aptamer-functionalized fiber interface (3D-Apt@AuNPs@Au wire–ITO) was built and employed for specifically sorptive extraction of CAPs from the milk samples with a matrix complex based on the high affinity of the aptamer for the targets. The extraction capacities for CAP, TAP and FF were 887, 840 and 801 ng per fiber, respectively. The enrichment folds were more than 500 times, which is 3.1 folds higher than that of the 2D-Apt@AuNPs–ITO fiber and 6.6 folds higher than that of the 1D-Apt@Au wire–ITO fiber. Afterwards, several similar fibers were assembled together into an array for simultaneous enrichment of three CAPs from 12 samples in one run. Finally, the adsorbed targets were washed away using a pH 8.5 0.1 M Tris–HCl buffer and then detected by high performance liquid chromatography (HPLC)-Diode Array Detector (DAD). The parameters, including extraction temperature, shuttle rates, extraction and desorption pH, and extraction and desorption time, were investigated and discussed. Under the optimized conditions, the limits of detection (LOD) and quantitation (LOQ) were determined as 0.262–0.293 and 0.864–0.967 ng mL−1, respectively, for several CAPs. The fibers array can be applied in replicate batch-extraction for at least 60 extraction cycles with a recovery of over 80%. The SPME fibers assay coupled with HPLC detection possessed advantages of high-throughput, high selectivity and adsorption capacity in one run. Furthermore, the process is environmentally friendly without using organic solutions during the entire extraction process. Thus, the method is a universal platform that can be extended to the selective extraction of other organic pollutant residues if the modified aptamers are changed.

An ultrasensitive electrochemical aptasensor for simultaneous detection of oxytetracycline (OTC) and kanamycin (KAN) has been developed based on metal ions doped metal organic frame materials (MOFs) as signal tracers and RecJf exonuclease-catalyzed targets recycling amplification. The aptasensor consists of capture beads (the anti-single-stranded DNA Antibody, as anti-ssDNA Ab, labeled on Dynabeads) and nanoscale MOF (NMOF) based signal tracers (simplified as Apts-MNM, the NMOF labeled with metal ions and the aptamers). Particularly, the MOF (UiO-66-NH2), with large internal surface areas, ultrahigh porosity and abundant amine groups in the pores, was employed as substrates to carry plenty of metal ions (Pb2+ or Cd2+) and label aptamers of OTC or KAN. Thus, the aptasensor is formed by the specific recognition between anti-ssDNA Ab and aptamers. In the presence of targets (OTC and KAN), aptamers prefer to form targets-Apts-MNM complexes in lieu of anti-ssDNA Ab-aptamer complexes, which results in the dissociation of Apts-MNM from capture beads. With the employment of RecJf exonuclease, targets-Apts-MNM in supernatant was digested into mononucleotides and liberated the target, which can further participate in the next reaction cycling to produce more signal tracers. After magnetic separation, the enhanced square wave voltammetry (SWV) signals were produced from signal tracers. The aptasensor exhibited a linear correlation in the range from 0.5 pM to 50 nM, with detection limits of 0.18 pM and 0.15 pM (S/N=3) toward OTC and KAN respectively. This strategy provides specificity and sensitive approach for multiplex antibiotics detection and has promising applications in food analysis.

A quick and specific pretreatment method based on a series of extraction clean-up disks, consisting of molecularly imprinted polymer monoliths and C18 adsorbent, was developed for the specific enrichment of salbutamol and clenbuterol residues in food. The molecularly imprinted monolithic polymer disk was synthesized using salbutamol as a template through a one-step synthesis process. It can simultaneously and specifically recognize salbutamol and clenbuterol. The monolithic polymer disk and series of C18 disks were assembled with a syringe to form a set of tailor-made devices for the extraction of target molecules. In a single run, salbutamol and clenbuterol can be specifically extracted, cleaned, and eluted by methanol/acetic acid/H2 O. The target molecules, after a silylation derivatization reaction were detected by gas chromatography-mass spectrometry. The parameters including solvent desorption, sample pH, and the cycles of reloading were investigated and discussed. Under the optimized extraction and clean-up conditions, the limits of detection and quantitation were determined as 0.018-0.022 and 0.042-0.049 ng/g for salbutamol and clenbuterol, respectively. The assay described was convenient, rapid, and specific; thereby potentially efficient in the high-throughput analysis of β2 -agonists residues in real food samples.

The effect of different concentrations (0, 0.1 and 0.5%, v/v) of black pepper essential oil (BPEO) on thiobarbituric acid reactive substances (TBARS), meat color, the percentage of metmyoglobin (MetMb%), microbiological parameters and total volatile basic nitrogen (TVB-N) of pork loins stored at 4°C for 9days was evaluated. BPEO treatments showed lower TBARS, MetMb%, yellowness (b*) values, Pseudomonas spp. and Enterobacteriaceae count and TVB-N values and higher lightness (L*) and redness (a*) values than the control during storage; the effectiveness of BPEO was dose-dependent. The retardation of the formation of MetMb by adding BPEO ensured higher L* and a* values and lower b* values than the control at 6 and 9days; the MetMb content has a similar trend to the lipid oxidation. The lower TVB-N value of BPEO treatments than the control could be attributed to the inhibition of Pseudomonas spp. and Enterobacteriaceae. Gram-negative bacteria were more sensitive than Gram-positive bacteria to BPEO.

In this work, a novel homogeneous and signal “off–on” aptamer based fluorescence assay was successfully developed to detect chloramphenicol (CAP) residues in food based on the fluorescence resonance energy transfer (FRET). The vesicle nanotracer was prepared through labeling single stranded DNA binding protein (SSB) on limposome-CdSe/ZnS quantum dot (SSB/L-QD) complexes. It was worth mentioning that the signal tracer (SSB/L-QD) with vesicle shape, which was fabricated being encapsulated with a number of quantum dots and SSB. The nanotracer has excellent signal amplification effects. The vesicle composite probe was formed by combining aptamer labeled nano-gold (Au-Apt) and SSB/L-QD. Which based on SSB's specific affinity towards aptamer. This probe can't emit fluoresce which is in “off” state because the signal from SSB/L-QD as donor can be quenched by the Au-aptas acceptor. When CAP was added in the composite probe solution, the aptamer on the Au-Apt can be preferentially bounded with CAP then release from the composite probe, which can turn the “off” signal of SSB/L-QD tracer into “on” state. The assay indicates excellent linear response to CAP from 0.001 nM to 10 nM and detection limit down to 0.3 pM. The vesicle probes with size of 88 nm have strong signal amplification. Because a larger number of QDs can be labeled inside the double phosphorus lipid membrane. Besides, it was employed to detect CAP residues in the milk samples with results being agreed well with those from ELISA, verifying its accuracy and reliability.

The β2-adrenergic receptor (β2-AR) plays a crucial role in pancreatic ductal adenocarcinoma (PDAC) progression. In this report, we identified poly(rC)-binding protein 2 (PCBP2) as a novel binding partner for β2-AR using immunoprecipitation-mass spectrometry (IP-MS) approach. The association between β2-AR and PCBP2 was verified using reciprocal immunoprecipitation. Importantly, we found significant interaction and co-localization of the two proteins in the presence of β2-AR agonist in Panc-1 and Bxpc3 PDAC cells. β2-AR-induced recruitment of PCBP2 led to augmented protein level of c-myc in PDAC cells, likely as a result of enhanced internal ribosome entry segment (IRES)-mediated translation of c-myc. The activation of β2-AR accelerated cell proliferation and colony formation, while knockdown of PCBP2 or c-myc restrained the effect. Furthermore, overexpression of PCBP2 was observed in human PDAC cell lines and tissue specimens compared to the normal pancreatic ductal epithelial cells and the non-cancerous tissues respectively. Overexpression of β2-AR and PCBP2 was associated with advanced tumor stage and significantly worsened prognosis in patients with PDAC. Our results elucidate a new molecular mechanism by which β2-AR signaling facilitates PDAC progression through triggering PCBP2-dependent c-myc expression.

A novel ratiometric electrochemiluminescent (R-ECL) aptasensor array was fabricated on a homemade screen-printed carbon electrode (SPCE) for antibiotic chloramphenicol (CAP) based on the ratio of working signal to internal reference signal. The SPCE substrate consists of a common Ag/AgCl reference electrode, carbon counter electrode and two spatial-resolved carbon working electrodes (WE1 and WE2). In the system, luminol-gold nanoparticles (L-Au NPs) as working signal tags were modified on WE1, and CdS quantum dots (QDs) were modified on WE2 as internal reference to provide a correction for avoiding the environmental effects. The L-Au NPs at WE1 were functionalized with a CAP aptamer′s DNA complementary (DNA1) and then CAP aptamer (DNA2) that was tagged with chlorogenic acid (CA) as quenchers of L-Au NPs. Upon CAP adding to WE1, the DNA2-CAP complexes were formed due to the highly affinity of CAP towards DNA2. Meanwhile, it could release the CA, which recovered the ECL of L-Au NPs. This ratio of ECL signals for quantification between target probes (at WE1) to internal standard probes (at WE2) could reduce the matrix environmental interference to a certain degree. Moreover, the two probes immobilized on two working electrodes while not one electrode, could also reduce cross-talk interference between each other. Such R-ECL approach offers a selective and sensitive platform and shows a great utility for detection of CAP in the food analysis.

The effect and mechanism of myofibrillar protein (MP) gelation influenced by konjac glucomannan (KG) addition were studied. The KG addition significantly improved gel strength and water holding capability (WHC) of MP-KG composite gel, but it had additive limitation at 1.0%. The SEM showed that KG (1.0%) reduced the appearance of moisture channels and promoted the formation of an integral MP gel network. Raman spectroscopy showed that KG addition (1.0%) promoted the protein unfolding and the interaction of hydrophobic groups during thermal processing. However, the KG (1.0%) would form continuous viscous hydrogel and interpenetrate with the MP solution, which hindered the interaction of hydrophobic groups during thermal process, and the MP formed a loose and degraded final structure. Hence, MP gels produced with the addition of KG underwent a transformation from a loose structure to a compact structure to an unaggregated structure, which was influenced by moisture stability and phase separation behavior.

The sensitivity of current lateral flow strip (LFS) based assays is a technical bottleneck. The authors describe a method for signal amplification to give a 10- to 25-fold improvement of the detection limit without compromising the assay time and operational mode. The assays includes the following steps: (a) immobilization of melamine antibody on gold nanoparticles (AuNPs); (b) immobilization of BSA antibody on other AuNPs; (c) coating a nitrocellulose (NC) membrane with coating antigen and secondary antibody against the melamine antibody as the test line and control line, respectively; (d) introducing an enhancement pad for signal amplification by immuno-recognition of the blocking protein on the first conjugation pad by the antibody on the enhancement pad. This results in dual labeling of AuNPs on the test line and enhances the optical intensity of test line at the same time of detection. The signal amplification makes the optical intensity change of the test line distinguishable even at low concentrations. The assay has a detection limit of 1.4 ppb (at an S/N ratio of 3). It was applied to the determination of melamine in milk, and the results obtained with this LFS are in good agreement with those obtained with instrumental methods. This demonstrates the practical applicability of the amplified LFS to real food samples. In our perception, this approach has a wide scope because it paves the way to the systematic amplification of the sensitivity of lateral flow strips.

In this paper, a novel aptamer-functionalized stir bar sorptive extraction (SBSE) was developed for selective enrichment of the low abundance polychlorinated biphenyls (PCBs) from fish samples. This approach was based on the immobilization of aptamer which could recognize 2,3',5,5'-tetrachlorobiphenyl (PCB72) and 2',3',4',5,5'-pentachlorobiphenyl (PCB106) on one kind of metal-organic frameworks (Zn4O(BDC)3, MOF-5). MOF-5 as a substrate was prepared by potential-controlled cathodic electrodeposition on stainless steel. This aptamer-functionalized stir bar sorptive extraction (Apt-MOF SBSE) fiber could be facile synthesized in one-step. PCB72 and PCB106 were employed as target analytes for selective extraction by the developed method. The adsorbed targets could be desorbed easily in pH 3.0 100mM glycine-HCl buffers and then extracted by the methylene chloride. Afterwards, the detection was carried out with gas chromatography-tandem mass spectrometry (GC-MS). The Apt-MOF SBSE pretreatment coupled with GC-MS exhibited high selectivity, good binding capacity, stability and reproducibility for the detection of PCBs. It provided a linear range of 0.02-250ngmL(-1) with a good coefficient of determination (R(2)=0.9991-0.9996) and the detection limit was 0.003-0.004ngmL(-1). More importantly, the method was successfully utilized for the determination of PCBs in fish samples with good enrichment factor (1930-2304). Therefore, this new SBSE coating opens up the possibility of selective enrichment of a given target PCBs from complex fish samples.

The article describes a multiplex aptamer based voltammetric assay for the food pollutants chloramphenicol (CAP) and polychlorinated biphenyl-72 (PCB72). The method is based on the displacement of a nanotracer (an aptamer-labeled magnetic dendritic probe) by the analytes which cause the release of the corresponding encoded nanotracers. Thiolated aptamers of CAP and PCB72 were first self-assembled on magnetic gold nanoparticles (Fe3O4@Au) as capture probes to concentrate the target analytes CAP and PCB72, respectively. Next, their hybridized complementary strands (cDNA1 or cDNA2) and a dendritic polymerase were linked to quantum dots (CdS or PbS) to form the respective nanotracers. Finally, encoded composite magnetic probes were obtained through hybridization reaction between aptamers and cDNAs. Once CAP and PCB72 are recognized by the composite probes, the nanotracers are released into the supernatant where they can be detected simultaneously by voltammetry of the metal ion markers Cd(II) and Pb(II) at −0.81 and −0.57 V (vs. Ag/AgCl), respectively. The concentration measured for Cd(II) and Pb(II) are directly proportional to the concentrations of CAP and PCB72, respectively, in the range from 0.001 to 100 ng mL−1. The detection limits for CAP and PCB72 are 0.33 and 0.35 pg mL−1, respectively (at an S/N ratio of 3), which is 2 to 3 orders of magnitude lower than the routinely performed and commercially available ELISA. The method is perceived to possess large potential in that it may be applied to other antibiotics by using the appropriate aptamers.

In this work, a fluorescence aptasensor has been developed to detect trace chloramphenicol based on FRET and exonuclease-assisted target recycling. Firstly, the composite probe for CAP was prepared through the immunoreactions between the capture probe based on dsDNA antibody labeled on Fe 3 O 4 @Au nanoparticles and the nanotracer using double strand aptamer (aptamer hybrid with its complementary DNA) labeled on core-shell SiO 2 @Au. When the composite probe solution was mixed with CAP, the aptamer on the nanotracer preferentially bounded with CAP, and then released cDNA-SiO 2 @Au and CAP-Apt complex to the supernatant. This is because anti-DNA on capture probes can’t recognize the ssDNA. The exonuclease I (Exo I) added into the supernatant can further digest the aptamer-CAP from the 3′-end of aptamer and release CAP again, which can further participate in new cycle to react with the probes. The supernatant containing numerous SiO 2 @Au could efficiently quench the fluorescence response of CdSe QDs by FRET. Experimental results showed the CAP detection owning a linearity range of 0.001–10 ng mL −1 and detection of limit (LOD) of 0.0002 ng mL −1 . Besides, the results of our method for CAP detection in the fish samples agreed well with those from ELISA, verifying its accuracy and reliability.

Herein, a facile, signal-on and homogenous fluorescence assay using novel aptamer-dsDNA antibody–quantum dot probes was designed for detecting antibiotic residues. In this assay, the fluorescent probes were fabricated by using a double-stranded DNA antibody (dsDNA Ab) covalently bonded on the surface of CdSe quantum dots. The antibody can bind double-stranded DNA (dsDNA) specifically. When dsDNA was added, the fluorescence could be efficiently quenched because the probes came into contact with each other with dsDNA as the bridge. The dsDNA was formed between an aptamer towards chloromycetin (CAP) and its complementary strand DNA (cDNA). When CAP was added into the reaction system, the aptamer reacted with CAP preferentially and the dsDNA was unwinded to single strand DNA (ssDNA) which cannot be recognized by the dsDNA antibody. Thus the probes were separated and fluorescence was recovered. Based on the scheme, a signal-on fluorescence assay for detecting antibiotics in a homogenous aqueous phase was developed. Under the optimized conditions, the assay shows a good liner range from 0.05 ng mL−1 to 100 ng mL−1 and the limit of detection (LOD) is 0.002 ng mL−1. If the analyte is changed, the assay can also be employed only by changing the corresponding aptamer and its cDNA. What's more, the probes can be reused at least 10 times with the recovery above 90%. The fluorescence assay is facile and has promising application for detecting antibiotic contaminants in biological and environmental samples.

In this study, a highly effective clean-up adsorbent was developed for eliminating matrix interferences, especially main organochlorine pesticide residues during the determination of highly chlorinated polychlorinated biphenyls in seafood. The multifunctional adsorbent was prepared by grafting carboxymethyl-β-cyclodextrin on the surface of amino functionalized mesoporous nanoparticles. The amino group functionalized mesoporous SiO2 can remove most of matrix interference in samples. Moreover, carboxymethyl-β-cyclodextrin has stronger host–guest complexation with 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane, 2,2-bis(p-chlorophenyl)-1,1-dichloro-ethylene, and 1,1-dichloro-2,2-bis(p-chloropheny)ethane. However, it showed weaker adsorption ability toward highly chlorinated polychlorinated biphenyls due to a steric hindrance effect. Based on this, a gas chromatography-mass spectrometry method coupled with the multifunctional adsorbent as a clean-up adsorbent for dispersive solid phase extraction was developed for the analysis of several highly chlorinated polychlorinated biphenyls in seafood samples. The results indicate that the multifunctional adsorbent as a purification material can easily and effectively remove matrix interferences in seafood samples within a short time. The recoveries for polychlorinated biphenyls were in the range of 88.4–103.2%, with relative standard deviations varying between 1.3 and 5.7%.

A “signal-on’’ aptasensor was developed for simultaneous detection of chloramphenicols (CAP) and polychlorinated biphenyl-72 (PCB72) with a novel multi-metal ions encoded nanospherical brushes as nanotracers. To construct the assay, the respective aptamer of CAP and PCB72 labeled magnetic gold nanoparticles as capture probes (aptamer-MGPs), and their complementary single strand DNA (s-DNA) encoded metal ions (Cd 2+ and Pb 2+ ) on nanospherical branched polyethylene imine brushes as tracers (s-DNA-MSPEIs), were simultaneously synthesized. After that, the capture probe and tracers were connected through a hybridization reaction between s-DNA and aptamers. In the presence of CAP and PCB72, the analytes could react with the aptamers on capture probes and release the tracers into supernatant after magnetic separation. The released tracers with metal ions (Cd 2+ and Pb 2+ ) could be simultaneously detected through the square wave voltammetry (SWV) without acid dissolution, which can switch the signals of the biosensor to “on’’ state. Under optimal conditions, the assay could detect CAP and PCB72 as low as 0.3 pg mL −1 with the dynamitic range from 0.001 to 100 ng mL −1 and exhibited excellent selectivity. More importantly, the strategy can be extended easily to other targets after changing the corresponding aptamers and other metal ions tracers, which provides a promising and facile approach in multiplex detection of ultra-trace level of pollutants in food safety without more complex separation and washing steps.

The effects of high pressure (100–500 MPa) on chemical forces and water holding capacity of heat-induced myofibrillar protein (MP) gel were investigated. As pressure increased, total sulfhydryl (SH) group content decreased and absolute value of zeta potential increased, which suggested the formation of disulfide bonds and increased the strength of electrostatic repulsion. Surface hydrophobicity and normalized intensity of the 760 cm −1 band showed a maximum value at 200 MPa, indicating that 200 MPa was the optimum pressure for hydrophobic interactions. Hydrogen bonding of MP gel was strengthened at pressures of 300 MPa and above. Bound water (T 2b ) had lower water mobility and was more closely associated with proteins. Free water (T 22 ) had higher water mobility. More free water was attracted by proteins or trapped in gel structure, and transferred to bound or immobilized water as pressure increased. A value of 200 MPa was the optimum pressure for the water holding capacity of MP gel.

In this work, several kinds of the metal-organic framework (MOF) were evaluated the adsorption performance to PCB. Finally, MOF-5(Fe) was introduced in stir bar sorptive extraction (SBSE) as the adsorbent to extract six polychlorinated biphenyls (PCBs). Nd-Fe-B permanent magnet was employed as stir bar, which was then coated with Fe3O4-MOF-5(Fe) composite magnetic material, which was prepared by solvothermal method. The stir bar was then employed to extract and enrich six indicator PCBs (2,2',5,5'-tetrachlorobiphenyl, 2,2',4,5,5'-pentachlorobiphenyl, 2,2',3,4,4',5-hexachlorobiphenyl, 2,3,4,4,5-pentachlorobiphenyl, 2,2',4,4',5,5'-hexachlorobiphenyl, 2,2',3,4,4',5,5'-heptachlorobiphenyl) under stirring, then eluted by n-hexane under ultrasound. Its saturated adsorption amount was found to be 17.0-17.8 mg g(-1) and only 30 min were needed to reach adsorption equilibrium. The MOF-stir bar can be reused for 60 times with the recovery above 80%, which exhibited good stability. Under the optimal experimental conditions, MOF-5(Fe) based SBSE was coupled with GC-MS for detecting six PCBs. The limits of detection (S/N=3) of the developed method were 0.061-0.096 ng g(-1), with enrichment factors of 50-100 fold. And the linear ranges were 0.01-500 μg L(-1). The new method was successfully applied to assess PCBs in fish samples with satisfactory recovery ranging from 94.3% to 97.5%.

The effects of the partial substitution of NaCl with KCl, MgCl2 and CaCl2 on the chemical forces and hardness of heat-induced myofibrillar protein (MP) gel were investigated. Compared with the normal-sodium-level MP gels (0.6 mol/L NaCl), low-sodium-level MP gels (0.4 mol/L NaCl) resulted in weaker disulphide bonds, hydrophobic interactions, electrostatic interactions, and stronger hydrogen bonds. Partial substitution of NaCl with KCl had no significant impacts on the chemical forces. MgCl2 and CaCl2 contributed to stronger hydrophobic interactions, and weaker hydrogen bonds and electrostatic interactions (p

The article describes a method for rapid and visual determination of Hg(II) ion using unmodified gold nanoparticles (Au-NPs). It involves the addition of Au-NPs to a solution containing Hg(II) ions which, however, does not induce a color change. Next, a solution of lysine is added which induces the aggregation of the Au-NPs and causes the color of the solution to change from wine-red to purple. The whole on-site detection process can be executed in less than 15 min. Other amines (ethylenediamine, arginine, and melamine) were also investigated with respect to their capability to induce aggregation. Notably, only amines containing more than one amino group were found to be effective, but a 0.4 μM and pH 8 solution of lysine was found to give the best results. The detection limits for Hg (II) are 8.4 pM (for instrumental read-out) and 10 pM (for visual read-out). To the best of our knowledge, this LOD is better than those reported for any other existing rapid screening methods. The assay is not interfered by the presence of other common metal ions even if present in 1000-fold excess over Hg(II) concentration. It was successfully applied to the determination of Hg(II) in spiked tap water samples. We perceive that this method provides an excellent tool for rapid and ultrasensitive on-site determination of Hg(II) ions at low cost, with relative ease and minimal operation.

Recent studies have identified that ErbB3 binding protein 1 (EBP1) is broadly expressed in various cancer tissues and critically involved in plenty of biological processes in this regard. However, the functional role of EBP1 in pancreatic ductal adenocarcinoma (PDAC) has never been elucidated. In this study, we found that EBP1 could serve as a prognostic biomarker of PDAC. Western blot analysis revealed that EBP1 was remarkably upregulated in PDAC tissues and cell lines. Using immunohistochemical analysis, we showed that the expression of EBP1 was correlated with tumor size (P = 0.004), histological differentiation (P = 0.041), and tumor node metastasis (TNM) stage (P = 0.000). Notably, Kaplan–Meier curve showed that high expression of EBP1 predicted significantly worsened prognosis of PDAC patients (P = 0.001). In addition, knockdown of EBP1 expression suppressed PDAC cell proliferation and retarded cell cycle progression. Furthermore, depletion of EBP1 induced the apoptosis of Panc-1 cells. Of great interest, we found that EBP1 interacted with anti-apoptotic protein, Bcl-xL, and promoted its accumulation. In summary, our results suggest that EBP1 is a novel prognostic indicator and potential therapeutic target of PDAC, shedding new insights into the important role of EBP1 in cancer development.

Since the introduction of genetically modified organisms (GMOs), there has been on-going and continuous concern and debates on the commercialization of products derived from GMOs. There is an urgent need for development of highly efficient analytical methods for rapid and high throughput screening of GMOs components, as required for appropriate labeling of GMO-derived foods, as well as for on-site inspection and import/export quarantine. In this study, we describe, for the first time, a multi-labeling based electrochemical biosensor for simultaneous detection of multiple DNA components of GMO products on the same sensing interface. Two-round signal amplification was applied by using both an exonuclease enzyme catalytic reaction and gold nanoparticle-based bio-barcode related strategies, respectively. Simultaneous multiple detections of different DNA components of GMOs were successfully achieved with satisfied sensitivity using this electrochemical biosensor. Furthermore, the robustness and effectiveness of the proposed approach was successfully demonstrated by application to various GMO products, including locally obtained and confirmed commercial GMO seeds and transgenetic plants. The proposed electrochemical biosensor demonstrated unique merits that promise to gain more interest in its use for rapid and on-site simultaneous multiple screening of different components of GMO products.

Texture profile analysis has been shown as an effective method for evaluating the quality of meats under different modes. The most common texture profile analysis mode, the two-bite test, is widely used to simulate chewing; however, the consistency is not always satisfactory. In the present study, another test mode (stress-relaxation test) was applied and the data were fitted to Gaussian function using 12 coefficients. A series of indices (X1: the X-value of the point had greatest curvature of the fitted curve; X2: the x-value of the point that the tangential slope of the fitted curve was –0.01; X2-X1: X2 minus X1; Y2: the y-value of the point that the tangential slope of the fitted curve was –0.01) was chosen from the fitted curve to estimate the texture in the stress-relaxation test, and the coefficient of variation of the indices of the two methods was also evaluated. In general, the new method showed improved consistency that may be suitable for evaluation of meat texture.

This study was designed to investigate the effect of rice–based fat substitute (FS) on heat-induced gelation of myofibrillar proteins (MP) from chicken breast muscle. The secondary structure, calorimetric and rheological attributes (α-helix, β-sheet, heat flow and G’) of FS and MP mixtures were measured during gel formation. The results indicated that the addition of FS led to easier denaturation of myosin but delayed denaturation of actin. The α-helix content in the MP-FS mixture was lower than that of MP, whilst β-sheet content in the MP-FS mixture was higher than that of MP when heating temperature was higher than 60 °C, indicating that the addition of FS could promoted MP molecules unfolding and aggregating at higher temperature. The G’ value of the MP-FS mixture was higher than that of MP during heating. The initial gelling temperatures of the MP sample and the MP-FS sample were 42 °C according to G’ curves. The hardness value of the MP-FS gel was higher than that of the MP gel at temperature over 60 °C, and reached the maximum value at . Scanning electron microscopy showed that FS changed the microstructure of MP gel. It was concluded that the addition of FS promoted MP molecule unfolding, aggregating and gelling at heating temperature over 60 °C, but FS did not change the initial gelling temperature of MP molecules and the optimal gel-forming temperature.

A novel colorimetric aptasensor was developed for sensitive and selective determination of chloramphenicol (CAP) based on gold nanoparticles (AuNPs) labeled with Power Vision (PV) and magnetic separation. PV, with a high enzyme-to-antibody ratio, is composed of a compact enzyme-linker antibody conjunction. In this assay, an aptamer of CAP was immobilized on Fe3O4@Au magnetic nanoparticles as a capture probe (AuMNPs–Apt) to concentrate target CAP. The complementary DNA (cDNA) and PV were both labeled on AuNPs to form a nano-peroxidase polymer as a signal tag (cDNA–AuNPs–PV). And the special tags could hybridize with the aptamer and cDNA to form AuMNP–Apt/cDNA–AuNP–PV conjugates. In the presence of CAP, the aptamer preferentially bound to CAP and caused the dissociation of some cDNA–AuNPs–PV on the conjugates with magnetic separation. PV, carried on signal tags, could greatly catalyze 3,3′,5,5′-tetramethylbenzidine (TMB) leading to color development, which could be quantified by Ultraviolet-visible (UV-vis) spectroscopy. A linear response to CAP concentration in the range of 0.05–200 ng mL−1 was obtained by this proposed method, with a low detection limit down to 0.02 ng mL−1. Besides, this assay was successfully employed to analyze CAP in fish and pork samples, whose results were consistent with those of the conventional enzyme-linked immunosorbent assay (ELISA) method.

Herein, an ultrasensitive and selective colorimetric assay for antibiotics, using chloramphenicol (CAP) as the model analyte, was developed based on magnetic aptamer-HRP-platinum composite probes and exonuclease-assisted target recycling. The composite probes were prepared through immunoreactions between the double stranded DNA antibody (anti-DNA) labeled on core-shell Fe3O4@Au nanoparticles (AuMNP-anti-DNA) as the capture probe, and the double stranded aptamer (aptamer hybrid with its complementary oligonucleotides) labeled on Pt@HRP nanoparticles as the nanotracer (ds-Apt-HRP-PtNPs). When the CAP samples were incubated with the probes for 30 min at room temperature, they could be captured by the aptamer to form a nanotracer-CAP complex, which was then released into the supernatant after magnetic separation. This is because the anti-DNA on the capture probes cannot recognize the single strand aptamer-CAP complex. The exonuclease I (Exo I) added into the supernatant can further digest the aptamer-CAP from the 3'-end of the aptamer and the CAP in the aptamer-CAP complex can be released again, which can further participate in a new cycling process to react with the probes. Pt and HRP in the nanotracer could both catalyze and dual amplify the absorbance at 650 nm ascribed to the 3,3',5,5'-tetramethylbenzidine (TMB)-H2O2 system. Moreover, Exo I can assist the target recycling, which can further amplify the signal. Thus, the triple amplified signal can be quantified by ultraviolet-visible spectroscopy. The experimental results showed that the CAP detection possessed a linear range of 0.001-10 ng mL(-1) and a detection limit of 0.0003 ng mL(-1) (S/N = 3). The assay was successfully employed to detect CAP in milk, which is much more facile, time saving, and sensitive than the commercial ELISA kits.

In this study, the effect and mechanism of myofibrillar protein (MP) gelation influenced by the hydration characteristic of three polysaccharides were studied through puncture test, paraffin section, SEM and Raman spectroscopy. The gel strength and water holding capability reflect that MP gelation only significantly improves until modified starch (MS) addition beyond 1.0%. The MS granule improves MP gel property through simply physical swelling effect. At gelatinization temperature, MS absorbs the moisture nearby to compress the MP three-dimensional networks, but the swelling effect is limited. The insoluble dietary fiber (IDF) improves MP gelation property through moisture stability. The IDF addition could lessen the appearance of moisture channel in MP gel networks and promote the interaction of hydrophobic groups. The MP gelation with 2.0% IDF addition has the highest gel strength (279 g) and water holding capability (91.87%). The konjac glucomannan (KG) (>1.0%) could degrade gel property of MP gelation through interpenetrate structure, because the KG hydrogel hinders the aggregation of the MP gel networks. In conclusion, the IDF, which has strong water-holding capability at room temperature and distribute individually, is the best polysaccharides-based fat replacement in low-fat restructured products.

The brain natriuretic peptide (BNP) is known to be an effective indicator of heart failure. It has been widely adopted as a parameter for the evaluation of heart function of cardiovascular and cerebrovascular diseases (CVDs). Current immune-recognition based methods for the detection of BNP are limited, to a certain extent, by the poor stability of the antibody and by high costs. The availability of an aptamer specific for BNP would greatly assist in the rapid and early diagnosis of CVDs. In order to screen for such an aptamer by the SELEX method, we have used magnetic microparticles (m-MPs) as the separation substrate for immobilization of target BNP. The use of m-MPs for rapid separation of combined aptamers enables bound oligonucleotides to be separated directly, quickly, and with high efficiency. After 14 rounds of selection, a panel of six aptamers against BNP was identified. Their dissociation constants range from 12.5 to 139 nM. The classical technique for conjugation of a target to m-MPs is known to be applicable to various fields, and we conclude that this m-MP-based SELEX process provides a general strategy for screening of specific aptamers against various analytes.

Novel label-free and multiplex aptasensors have been developed for simultaneous detection of several antibiotics based on a microchip electrophoresis (MCE) platform and target catalyzed hairpin assembly (CHA) for signal amplification. Kanamycin (Kana) and oxytetracycline (OTC) were employed as models for testing the system. These aptasensors contained six DNA strands termed as Kana aptamer-catalysis strand (Kana apt-C), Kana inhibit strand (Kana inh), OTC aptamer-catalysis strand (OTC apt-C), OTC inhibit strand (OTC inh), hairpin structures H1 and H2 which were partially complementary. Upon the addition of Kana or OTC, the binding event of aptamer and target triggered the self-assembly between H1 and H2, resulting in the formation of many H1-H2 complexes. They could show strong signals which represented the concentration of Kana or OTC respectively in the MCE system. With the help of the well-designed and high-quality CHA amplification, the assay could yield 300-fold amplified signal comparing that from non-amplified system. Under optimal conditions, this assay exhibited a linear correlation in the ranges from 0.001ngmL-1 to 10ngmL-1, with the detection limits of 0.7pgmL-1 and 0.9pgmL-1 (S/N=3) toward Kana and OTC, respectively. The platform has the following advantages: firstly, the aptamer probes can be fabricated easily without labeling signal tags for MCE detection; Secondly, the targets can just react with probes and produce the amplified signal in one-pot. Finally, the targets can be simultaneously detected within 10min in different channels, thus high-throughput measurement can be achieved. Based on this work, it is estimated that this detection platform will be universally served as a simple, sensitive and portable platform for antibiotic contaminants detection in biological and environmental samples.

An effective electrochemical aptasensor has been developed for the detection of multiplex antibiotics using Y-shaped DNA probes. These probes-based metal ions encoded the nanoscale metal-organic frameworks (NMOF) as a substrate, and circular strand-replacement DNA polymerization (CSRP) target triggered the amplification strategy. The Y-DNA probes (Y-DNA) were assembled using an assisted DNA probe (assisted DNA labeled with magnetic gold nanoparticles) which can hybridize to the captured DNA probe (consisting of aptamer and primer recognition region), and signal tags (NMOF encapsulating signal DNAs and different metal ions such as Pb2+ or Cd2+). Notably, NMOF was employed as the developed platform with a large specific area to load abundant metal ions that can produce distinguishable signals. In the presence of targets, chloramphenicol (CAP) and oxytetracycline (OTC) as models, the conformational change of the captured DNA can disassemble the Y-DNA probes that can consequently release the signal tags in the supernatant due to the high affinity of targets towards the aptamer domain than its complementary sequences. Subsequently, the exposed sequences of captured DNA serve as the initiators for triggering the target cyclic-induced polymerization with the assistance of Bst DNA polymerase. Thus, numerous signal tags could be detected by square wave voltammetry in the supernatant after magnetic separation, thereby amplifying the electrochemical signals. The proposed strategy exhibited a high sensitivity to antibiotics with a detection limit of 33 and 48 fM (S/N = 3) towards CAP and OTC, respectively. Moreover, this aptasensor showed promising applications for the detection of other analytes.

Twelve pieces of longissimus dorsi were processed into Chinese traditional dry-cured loins. The changes in the proteolylic enzymes activities, myofibrillar proteins degradation, and free amino acids content were investigated during processing. Compared with fresh piece (0 day), the cathepsin B + L and calpains activities decreased after dry-curing and maintained potential activities values of 23.25 and 15.04% in the final products, respectively. The myosin heavy chain (MHC) and C protein were intensely degraded at the dry-ripened stage; the 50 kDa desmin increased at day 2 and then disappeared at day 11. The total free amino acids content increased from 333.18 mg/100 g in the raw to 1096.54 mg/100 g at the end of the dry-ripening. This work provided a mechanism for the accumulation of free amino acids and predicted the proteolysis extent of myofibrillar proteins by monitoring the changes of three marker proteins (MHC, C protein and 50 kDa desmin) during Chinese traditional dry-cured loins processing.

A novel label-free, universal, and high throughput aptasensor was developed based on a microchip electrophoresis (MCE) platform for automatic detection of antibiotic residues in food. Firstly, chloramphenicol (CAP) was employed as a model to be captured by its aptamer probe (Apt). Then, the partial complementary oligonucleotide of CAP's aptamer (C-DNA) was introduced into the reaction system. Because the Apt-CAP complex can't further hybrid with free C-DNA, the amount of hybrid Apt-C-DNA double strand DNA (dsDNA) was less than that without adding the target. Finally, the above mixture was introduced into the microchip electrophoresis (MCE) platform for detection, both dsDNA and Apt-CAP can be separated and produce different fluorescence signals in the MCE. In a certain concentration range, the ratio of signal between dsDNA and Apt-CAP (IdsDNA/I Apt-CAP) was proportional to the concentration of targets. Under the optimum conditions, the ratio showed a satisfactory linearity range from 0.008 to 1ng/mL of CAP with a detection limit of 0.003ng/mL. Thus, a universal MCE-based assay was developed for quantifying CAP automatically. The method was also successfully applied in the different food samples for CAP detection, which showed a good recovery (Milk: 91.1-108%, Fish: 86.1-114%) and the results were consistent with that of ELISA. This method owned many merits as follows: firstly, MCE was a high throughput screening platform and the detection time is limited to 3min for each sample. Secondly, the aptamer probes can be directly used for detection without labeling any signal tag which can facilitate the preparation procedures of probes. Thirdly, the operation was easy just by the following steps: firstly, the mixture of aptamer probes were incubated followed adding C-DNA; then measurement was performed. Moreover, the assay with MCE platform can be used to detect other targets just by changing the corresponding aptamer probe; it can even realize simultaneous detection when the targets have aptamers with different number of base pairs. Above all, it's a high- throughput and prospective method which can be applied in high throughput screening of antibiotics in food safety.