Application of Surface-Enhanced Raman Spectroscopy Combined with Immunoassay for the Detection of Adrenoceptor Agonists.

Rapid, sensitive, and accurate detection of adrenoceptor agonists is a significant research topic in the fields of food safety and public health. Immunoassays are among the most widely used methods for detecting adrenoceptor agonists. In recent years, surface-enhanced Raman spectroscopy combined with immunoassay (SERS-IA) has become an effective technique for improving detection sensitivity. This review focuses on the innovation of Raman reporter molecules and substrate materials for the SERS-IA of adrenoceptor agonists. In addition, it also investigates the challenges involved in potentially applying SERS-IA in the detection of adrenoceptor agonists. Overall, this review provides insight into the design and application of SERS-IA for the detection of adrenoceptor agonists, which is critical for animal-derived food safety and public health.

A fluorescent aptasensor for highly sensitive and selective detection of carcinoembryonic antigen based on upconversion nanoparticles and WS2 nanosheets.

A highly sensitive fluorescent aptasensor for carcinoembryonic antigen (CEA) was developed by employing upconversion nanoparticles (UCNPs) as an energy donor and WS2 nanosheets as an energy acceptor, respectively. Polyacrylic acid (PAA) modified NaYF4:Yb/Er UCNPs and an amine modified CEA aptamer were linked together by a covalent bond. Owing to the physical adsorption between WS2 nanosheets and the CEA aptamer, the UCNPs-aptamer was close to WS2 nanosheets, resulting in upconversion fluorescence energy transfer from UCNPs to WS2 nanosheets, and the UCNP fluorescence was quenched. With the introduction of CEA into the UCNPs-aptamer complex system, the aptamer preferentially bound to CEA resulting in a change in spatial conformation which caused UCNPs to depart from WS2 nanosheets. As a result, the energy transfer was inhibited and the fluorescence of UCNPs was observed again, and the degree of fluorescence recovery was linearly related to the concentration of CEA in a range of 0.05-10 ng mL-1 with a limit of detection of 0.008 ng mL-1. Furthermore, the aptasensor based on UCNPs and WS2 nanosheets could be competent for detecting CEA in human serum, which suggests the great application potential of the proposed aptasensor in clinical diagnosis.

A Polyamidoamine-Based Electrochemical Aptasensor for Sensitive Detection of Ochratoxin A.

Sensitive detection of ochratoxin A (OTA) is significant and essential because OTA may pose risks to human and animal health. Here, we developed an electrochemical aptasensor for OTA analysis using polyamidoamine (PAMAM) dendrimers as a signal amplifier. As a carrier, PAMAM has numerous primary amino groups that can be coupled with thiolated complementary strand DNA (cDNA), allowing it to recognize aptamers bound to the surface of horseradish peroxidase (HRP)-modified gold nanoparticles (AuNPs), thereby improving the sensitivity of the aptasensor. When monitoring the positive samples, OTA was captured by the aptamer fixed on the HRP-conjugated AuNP surface by specific recognition, after which the formed OTA-aptamer conjugates were detached from the electrode surface, ultimately decreasing the electrochemical signal monitored by differential pulse voltammetry. The novel aptasensor achieved a broad linear detection range from 5 to 105 ng L-1 with a low detection limit of 0.31 ng L-1. The proposed aptasensor was successfully applied for OTA analysis in red wine, with recovery rates ranging from 94.15 to 106%. Furthermore, the aptasensor also exhibited good specificity and storage stability. Therefore, the devised aptasensor represents a sensitive, practical and reliable tool for monitoring OTA in agricultural products, which can also be adapted to other mycotoxins.

Affinity-Based Analysis Methods for the Detection of Aminoglycoside Antibiotic Residues in Animal-Derived Foods: A Review.

With the increasingly serious problem of aminoglycoside antibiotic residues, it is imperative to develop rapid, sensitive and efficient detection methods. This article reviews the detection methods of aminoglycoside antibiotics in animal-derived foods, including enzyme-linked immunosorbent assay, fluorescent immunoassay, chemical immunoassay, affinity sensing assay, lateral flow immunochromatography and molecular imprinted immunoassay. After evaluating the performance of these methods, the advantages and disadvantages were analyzed and compared. Furthermore, development prospects and research trends were proposed and summarized. This review can serve as a basis for further research and provide helpful references and new insights for the analysis of aminoglycoside residues. Accordingly, the in-depth investigation and analysis will certainly make great contributions to food safety, public hygiene and human health.

A novel fluorescent probe for the detection of formaldehyde in real food samples, animal serum samples and gaseous formaldehyde.

Formaldehyde (FA) is widely used as an adhesion promoter and dyeing aid in industrial production. Ingestion of a certain amount of formaldehyde may cause corrosive burns in the mouth, throat, and digestive tract. Therefore, it is very necessary to use simple and effective detection methods to ensure human health and food safety. Herein, a novel fluorescent probe NFD based on naphthalimide for the detection of formaldehyde in food was designed and synthesized. The probe had a remarkable fluorescence response to formaldehyde at 554 nm. And it exhibited fascinating advantages of good selectivity, high sensitivity, and low detection limit. In addition, the solid sensor prepared by loading the probe on the filter paper was successfully realized the visual detection of liquid and gaseous formaldehyde. More importantly, the probe possessed excellent stability in the detection of formaldehyde in real food samples and animal serum samples.

A bifunctional fluorescent probe based on PET & ICT for simultaneously recognizing Cys and H2S in living cells.

Most reported probes that respond to Cysteine (Cys) and Hydrogen sulfide (H2S) can only identify one analyte, or they were interfered with homocysteine (Hcy) and glutathione (GSH) when recognizing Cys and H2S. In addition, nitrobenzoxadiazole (NBD) ether, as one of thiols recognition sites, inevitably encounters the situation that Cys, GSH and H2S cannot be distinguished on the same channel at the cellular level. In this work, by introducing NBD ether and NBD amine, we constructed a bifunctional fluorescent probe NJB for dual-site response to Cys and H2S via PET & ICT processes. NJB has wonderful selectivity for identifying Cys and HS-, with limits of detection as low as 58.4 nM and 81.1 nM, respectively. Interestingly, NJB has been successfully applied to detect Cys and HS- in MCF-7 cells. Therefore, the probe that serves as a great tool for inquiring the physiological and pathological functions of Cys and H2S in living cells is promising.

The growth pattern of liver metastases on MRI predicts early recurrence in patients with colorectal cancer: a multicenter study.

OBJECTIVES: The multicenter study aimed to explore the relationship between the growth pattern of liver metastases on preoperative MRI and early recurrence in patients with colorectal cancer liver metastases (CRCLM) after surgery. METHODS: A total of 348 CRCLM patients from 3 independent centers were enrolled, including 130 patients with 339 liver metastases in the primary cohort and 218 patients in validation cohorts. Referring to the gross classification of hepatocellular carcinoma (HCC), the growth pattern of each liver metastasis on MRI was classified into four types: rough, smooth, focal extranodular protuberant (FEP), and nodular confluent (NC). Disease-free survival (DFS) curve was constructed using the Kaplan-Meier method. RESULTS: In primary cohort, 42 (12.4%) of the 339 liver metastases were rough type, 237 (69.9%) were smooth type, 29 (8.6%) were FEP type, and 31 (9.1%) were NC type. Those patients with FEP- and/or NC-type liver metastases had shorter DFS than those without such metastases (p < 0.05). However, there were no significant differences in DFS between patients with rough- and smooth-type liver metastases and those without such metastases. The patients with FEP- and/or NC-type liver metastases also had shorter DFS than those without such metastases in two external validation cohorts. In addition, 40.5% of high-risk-type (FEP and NC) liver metastases converted to low-risk types (rough and smooth) after neoadjuvant chemotherapy. CONCLUSION: The FEP- and NC-type liver metastases were associated with early recurrence, which may facilitate the clinical treatment of CRCLM patients. KEY POINTS: • In the primary cohort, patients with FEP- and NC-type metastases had shorter disease-free survival (DFS) and a higher intrahepatic recurrence rate than patients without such metastases in the liver. • In the primary cohort, there were no significant differences in DFS or intrahepatic recurrence rate between patients with rough- and smooth-type metastases and those without such metastases in the liver. • High-risk patients had shorter DFS and a higher intrahepatic recurrence rate than low-risk patients in primary and external validation cohorts.

Nanomaterial-based aptamer biosensors for ochratoxin A detection: a review.

Ochratoxin A (OTA) is a widely distributed mycotoxin that often contaminates food, grains and animal feed. It poses a serious threat to human health because of its high toxicity and persistence. Therefore, the development of an inexpensive, highly sensitive, accurate and rapid method for OTA detection is imperative. In recent years, various nanomaterials used in the establishment of aptasensors have attracted great attention due to their large surface-to-volume ratio, good stability and facile preparation. This review summarizes the development of nanomaterial-based aptasensors for OTA determination and sample treatment over the past 5 years. The nanomaterials used in OTA aptasensors include metal, carbon, luminescent, magnetic and other nanomaterials. Finally, the limitations and future challenges in the development of nanomaterial-based OTA aptasensors are reviewed and discussed.

Selective solid-phase extraction of four phenylarsonic compounds from feeds, edible chicken and pork with tailoring imprinted polymer.

The novel molecularly imprinted microspheres for four phenylarsonic compounds have been firstly prepared with the reversible addition-fragmentation chain transfer polymerization in a suspension system. The resulting polymeric microspheres were characterized by infrared spectrum, scanning electron microscope and differential scanning calorimetry. With serial adsorption experiments, the polymeric microspheres showed highly specific molecular recognition, fast mass transfer rate and robust adsorption of the substrates. Then, the imprinted polymer was used as the solid-phase extraction adsorbent to extract the phenylarsonic compounds from the feeds, edible chicken and pork. The cartridge was washed with 2 mL ethyl acetate and eluted with 3 mL of methanol- acetic acid (90:10, v/v). The recoveries of the molecularly imprinted solid-phase extraction (MISPE) column ranged from 83.4% to 95.1%. This work provided a versatile approach for the specific extraction of the organoarsenic compounds from complicated matrices and exhibited a bright future for the application of MISPE column.

Enzyme-linked immunoassay based on imprinted microspheres for the detection of sulfamethazine residue.

This study attempts to develop an enzyme-linked immunoassay (ELISA) using a molecularly imprinted polymer (MIP) as an artificial recognition element. The MIP microspheres were prepared using precipitation polymerization with SM2 as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linker. After the microspheres were coated in microtiter plate wells, the molecular imprinting ELISA (MI-ELISA) method was established based on the direct competition between free SM2 and horseradish peroxidase (HRP)-labelled SM2 in heterogeneous mode. The linear regression analysis data for the calibration curve showed a good linear relationship with a regression coefficient of 0.999 in the concentration range of 100µgL-1-3200µgL-1. Furthermore, following the selective solid-phase extraction (SPE) with bulk SM2 MIPs as the sorbent and MI-ELISA detection, the limits of detection and quantification were 6.8µgkg-1 and 20.4µgkg-1, respectively, for SM2 in swine muscle. For the first time, MI-ELISA combined with molecular imprinting SPE was developed to determine trace SM2 in real samples, and the results show that it can be a useful analytical tool for quick detection in residue analysis.

Strain improvement of Trichoderma viride for increased cellulase production by irradiation of electron and (12)C(6+)-ion beams.

OBJECTIVES: To improve cellulase production and activity, Trichoderma viride GSICC 62010 was subjected to mutation involving irradiation with an electron beam and subsequently with a (12)C(6+)-ion beam. RESULTS: Mutant CIT 626 was the most promising cellulase producer after preliminary and secondary screening. Soluble protein production and cellulase activities were increased mutifold. The optimum temperature, pH and culture time for the maximum cellulase production of the selected mutant were 35 °C, pH 5 and 6 days. The highest cellulase production was obtained using wheat bran. The prepared cellulases from T. viride CIT 626 had twice the hydrolytic performance with sawdust (83 %) than that from the parent strain (42.5 %). Furthermore, molecular studies demonstrated that there were some key mutation sites suggesting that some amino acid changes in the protein caused by base mutations had led to the enhanced cellulase production and activity. CONCLUSIONS: Mutagenesis with electron and (12)C(6+)-ion beams could be developed as an effective tool for improvement of cellulase producing strains.

Molecularly imprinted polymer for specific extraction of hypericin from Hypericum perforatum L. herbal extract.

The molecularly imprinted polymers (MIPs) were prepared by an oxidation-reduction polymerization system using a non-covalent molecularly imprinting strategy with hypericin as the template, acrylamide as the functional monomer and pentaerythritol triacrylate as the cross-linker in the porogen of acetone. The UV spectrum revealed that a cooperative hydrogen-bonding complex between hypericin and acrylamide might be formed at the ratio of 1:6 in the prepolymerized system. Two classes of the binding sites were produced in the resulting hypericin-imprinted polymer with the dissociation constants of 16.61µgL(-1) and 69.35µgL(-1), and the affinity binding sites of 456.53µgg(-1) and 603.06µgg(-1), respectively. The synthesized MIPs were characterized by scanning electron microscope, thermogravimetric and differential thermal analysis. High-performance liquid chromatography was used to investigate the adsorption and recognition properties of the MIPs. Selective binding of the template molecule was demonstrated in comparison to the analog pseudohypericin. After the Hypericum perforatum L. plant being air dried and finely ground, an extract was prepared by shaking the powder in a methanol-water solution (80:20, v/v), vacuum filtration though a Büchner funnel, liquid-liquid extraction with ethyl ether and ethyl acetate, and evaporating on a rotary evaporator until dry. With the sorbents of the optimized MIPs, a molecularly imprinted solid-phase extraction (MISPE) procedure was developed for enrichment and separation of hypericin from the Hypericum extract in the presence of interfering substances. The selective extraction of hypericin from herbal medicine was achieved with the recovery of 82.30%. The results showed that MISPE can be a useful tool for specific isolation and effective clean-up of target compounds from natural products.