A breakthrough of immunoassay format for hapten: recent insights into noncompetitive immunoassays to detect small molecules.

Immunoassay based on the antibodies specific for targets has advantages of high sensitivity, simplicity and low cost, therefore it has received more attention in recent years, especially for the rapid detection of small molecule chemicals present in foods, diagnostics and environments. However, limited by low molecular weight and only one antigenic determinant existed, immunoassays for these small molecule chemicals, namely hapten substances, were commonly performed in a competitive immunoassay format, whose sensitivities were obviously lower than the sandwich enzyme-linked immunosorbent assay generally adaptable for the protein targets. In order to break through the bottleneck of detection format, researchers have designed and established several novel noncompetitive immunoassays for the haptens in the past few years. In this review, we focused on the four representative types of noncompetitive immunoassay formats and described their characteristics and applications in rapid detection of small molecules. Meanwhile, a systematic discussion on the current technologies challenges and the possible solutions were also summarized. This review aims to provide an updated overview of the current state-of-the-art in noncompetitive immunoassay for small molecules, and inspire the development of novel designs for small molecule detection.

Molecular Evolution of Antiparathion Nanobody with Enhanced Sensitivity and Specificity Based on Structural Analysis.

Nanobody (Nb) has gained significant attention in immunoassays owing to its numerous advantages, particularly its ease of molecular evolution. However, the limited understanding of how high sensitivity and specificity attained for antihapten Nbs hamper the development of high-performance Nbs. Herein, the antiparathion Nb (Nb9) we prepared previously was chosen as the model, and an approach based on X-ray crystallography, molecular docking, and rational site-directed saturation mutation for constructing a rapid and effective platform for nanobody evolution was described. Based on the structural analysis, two mutants, namely Nb-D5 (IC50 = 2.4 ± 0.2 ng/mL) and Nb-D12 (IC50 = 2.7 ± 0.1 ng/mL), were selected out from a six-sites directed saturation mutation library, 3.5-fold and 3.1-fold sensitivity enhancement over Nb9 to parathion, respectively. Besides, Nb-D12 exhibited improved sensitivity for quinalphos, triazophos, and coumaphos (5.4-35.4 ng/mL), indicating its broader detection potential. Overall, our study advances an effective strategy for the future rational evolution of Nbs with desirable performance.

Design of an Antigen-Triggered Nanobody-Based Fluorescence Probe for PET Immunoassay to Detect Quinalphos in Food Samples.

Photoinduced electron-transfer (PET) immunoassay based on a fluorescence site-specifically labeled nanobody, also called mini Quenchbody (Q-body), exhibits extraordinary sensitivity and saves much time in the homogeneous noncompetitive mode and is therefore regarded as a valuable method. However, limited by the efficiency of both quenching and dequenching of the fluorescence signal before and after antigen binding associated with the PET principle, not all original nanobodies can be used as candidates for mini Q-bodies. Herein, with the anti-quinalphos nanobody 11A (Nb-11A) as the model, we, for the first time, adopt a strategy by combining X-ray structural analysis with site-directed mutagenesis to design and produce a mutant Nb-R29W, and then successfully generate a mini Q-body by labeling with ATTO520 fluorescein. Based on this, a novel PET immunoassay is established, which exhibits a limit of detection of 0.007 µg/mL with a detection time of only 15 min, 25-fold improved sensitivity, and faster by 5-fold compared to the competitive immunoassay. Meanwhile, the recovery test of vegetable samples and validation by the standard ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) both demonstrated that the established PET immunoassay is a novel, sensitive, and accurate detection method for quinalphos. Ultimately, the findings of this work will provide valuable insights into the development of triggered PET fluorescence probes by using existing antibody resources.

A highly sensitive electrochemical immunosensor based on electrospun nanocomposite for the detection of parathion.

For monitoring of the residual of parathion pesticide in food, herein, a sensitive and reliable electrochemical immunosensor based on cross-linked polyvinyl alcohol/citric acid nanofiber membrane (PVA/CA NFM) and horseradish peroxidase labeled anti-parathion nanobody was constructed. Firstly, the cross-linked PVA/CA NFM with extra-high surface area and uniform morphology was prepared and characterized. Then, the immunosensor was assembled and its analytical performances were evaluated. It exhibited high specificity and sensitivity to parathion with the liner range and limit of detection being 0.01-100 ng/mL and 2.26 pg/mL, respectively. Moreover, the biosensor kept almost 75% of its initial activity after regenerating 4 times, and remained 85% after 9 weeks of storage. Finally, the average recoveries from food samples were 96.20%-114.61% with the coefficient of variation being 1.06%-5.28%, which was correlate well with UPLC (R2 = 0.9964). Therefore, the sensor was demonstrated to be a feasible alternative for sensitive assay of parathion.

Scorpion venom heat-resistant synthetic peptide protects dopamine neurons against 6-hydroxydopamine neurotoxicity in C. elegans.

Parkinson's disease (PD) is a common neurodegenerative disease. The main pathological feature is the degeneration and loss of dopaminergic neurons in the substantia nigra, which leads to the significant decrease of dopamine content in the striatum. Our recent studies have shown that scorpion venom heat-resistant synthetic peptide (SVHRSP) have protective effects on neuroinflammation. In this study, using C. elegans induced by 6-hydroxydopamine (6-OHDA) as neurodegenerative model, we investigated the effect of SVHRSP on dopaminergic neurons neurotoxicity. Our results implied that SVHRSP treatment could improve the motor capacity in 6-OHDA-induced C. elegans and improve dopaminergic neuron mediated food sensitivity behavior. After SVHRSP treatment, dopaminergic neuron degeneration induced by 6-OHDA was significantly prevented along with a decreased α-synuclein aggregation and restored lipid deposition in C. elegans induced by 6-OHDA. We also observed the reduced levels of reactive oxygen species (ROS) after SVHRSP treatment in model-building C. elegans. In addition, the genes related to apoptosis, oxidative stress, like ctl-1, egl-1and cat-2 in C. elegans induced by 6-OHDA upregulated after treatment with SVHRSP. In conclusion, SVHRSP may impose anti-PD effect through its neuroprotective action on dopaminergic neurons. This study elucidates the effect and related mechanism of SVHRSP on PD and provides evidences for the therapeutic treatment of PD.

Nanobodies for Accurate Recognition of Iso-tenuazonic Acid and Development of Sensitive Immunoassay for Contaminant Detection in Foods.

The accurate analysis of chemical isomers plays an important role in the study of their different toxic effects and targeted detection of pollutant isomers in foods. The Alternaria mycotoxins tenuazonic acid (TeA) and iso-tenuazonic acid (ITeA) are two isomer mycotoxins with the lack of single analysis methods due to the similar structures. Antibody-based immunoassays exhibit high sensitivity and superior application in isomer-specific determination. Previously, various kinds of antibodies for TeA have been prepared in our group. Herein, highly specific nanobodies (Nbs) against ITeA mycotoxin were selected from immune nanobody phage display library, and one of Nbs, namely Nb(B3G3) exhibited excellent affinity, thermal stability as well as organic solvent tolerance. By molecular simulation and docking technology, it was found that stronger interaction between Nb(B3G3) and ITeA lead to higher affinity than that for its isomer TeA. Furthermore, a sensitive indirect competitive enzyme-linked immunosorbent assay (icELISA) was established with a limit of detection (LOD) of 0.09 ng/mL for ITeA mycotoxin. The recovery rate of ITeA in spiked samples was analyzed with 84.8%-89.5% for rice, 78.3%-96.3% for flour, and 79.5%-90.7% for bread. A conventional LC-MS/MS method was used to evaluate the accuracy of this proposed icELISA, which showed a satisfactory consistent correlation. Since the convenient strategy for nanobody generation by phage display technology, this study provide new biorecognition elements and sensitive immunoassay for analysis of ITeA in foods.

A high-resolution colorimetric immunoassay for tyramine detection based on enzyme-enabled growth of gold nanostar coupled with smartphone readout.

In this work, a specific monoclonal antibody against tyramine was produced based on a new hapten design. Then, we developed a high-resolution multicolor colorimetric immunoassay for tyramine based on this antibody by integrating enzyme-induced multicolor generation with smartphone-assistant signal readout. The multicolor generation is due to the shift of the local surface plasmon resonance band of gold nanostructure controlled by alkaline phosphatase-induced the growth of gold nanostars. Quantitative detection of tyramine was achieved via analyzing the red/blue channel values of assay solution's image taken by a smartphone with the support of a color recognizer application. The limit of detection of this immunoassay for tyramine detection in beef, pork and yoghurt was 19.7 mg/kg or L. The average recoveries were between 83 % and 103 %., and the results were validated by high performance liquid chromatography to be reliable. Overall, this developed immunoassay provides a promising platform for on-site detection of tyramine.

Long-Term Social Isolation-Induced Autophagy Inhibition and Cell Senescence Aggravate Cognitive Impairment in D(+)Galactose-Treated Male Mice.

Aging is associated with physiological and pathological changes and presents health complications, such as dementia. Isolation has also been associated with the experience of growing old. Both have been linked individually to the incidence of cognitive decline. In this present study, the effects of these two phenomena have been looked at in animal models where aging was induced with D(+)Galactose in mice who underwent long-term post-weaned social isolation (L-PWSI). Assessing cognitive function using Y-maze, Morris water maze (MWM), and passive avoidance tests (PATs) confirmed that cognition is impaired in either of the treatments but worsened when the D(+)Galactose mice were subjected to L-PWSI. Moreover, a synaptic protein, PSD95, and dendritic spines density were significantly reduced in the L-PWSI and D(+)Galactose-treated mice. Our previous study revealed that autophagy deficit is involved in cognitive impairment in the L-PWSI model. Here, we first report the inhibited cell cycle in L-PWSI, combined with the decreased autophagy, aggravates cognitive impairment in D(+)Galactose-treated mice. Beyond these, the autophagy and cell cycle mechanisms that link isolation and aging have been explored. The close association between isolation and aging in humans is very real and needs much research attention going forward for possible therapeutic interventions.

Ultrasensitive and rapid colorimetric detection of paraquat via a high specific VHH nanobody.

Rapid and quantitative detection of paraquat is crucial because of its high toxicity. Here, we developed an ultrasensitive time-resolved fluorescence immunochromatographic assay (TRFICA) strip based on our synthesized variable domain of heavy chain antibody (VHH, also called Nanobody) for paraquat detection. Briefly, the specific immunogen selected from six designed antigens was employed to immunize alpaca, and a high-efficiency capacity of 1.6 × 1013 pfu mL-1 phage display nanobody library was established for biopanning against paraquat. The selected nanobody exhibited high sensitivity (limit of detection (LOD) was 0.0090 ng mL-1 and IC50 was 0.0588 ng mL-1 in buffer) and stability to high temperatures and denaturants. The molecular docking results indicated that the π-π, cation-π, and hydrogen bond interactions between paraquat and the pocket-like structures of complementarity-determining regions (CDRs) in VHH played a critical role in the antibody-paraquat recognition, competition, and affinity processes. The constructed TRFICA recognized paraquat through a quantitative analysis using the strip reader, and showed no cross-reactivity with other herbicides, and a semi-quantitative analysis using the naked eye. Notably, the potential practical applications of the TRFICA evaluated by performing a quantitative analysis of paraquat in food samples (vegetables, fruits, and grain products) and biological samples (blood and urine) showed a recovery rate range between 76.7% and 133.3% with inter-assay coefficient variation lower than 18.5%. The nanobody from phage display libraries was effective for small molecule recognition and detection, and it is a vital tool for immunoassay.

Improved molecular softness of tadalafil hapten enhancing antibody performance in immunoassay: Evidence from computational chemistry.

The tadalafil-like compounds have appeared recently as adulterants in drinks and healthcare dietary supplements sourced from medicinal and edible food, which may cause illness and even death. In this work, the rationality of haptens was explored by computational chemistry and molecular simulation theories such as frontier molecular orbital (FMO)-based softness (S), three-dimensional (3D) structure, surface electrostatic potential (ESP), and lipophilic potential (LP). An antiserum from hapten H5 with the highest softness and maintaining the appropriate three-dimensional (3D) structure showed the optimal immunoassay performance, indicating an increasing softness was a critical factor for effective hapten. Based on the antibody induced by hapten H5, an indirect competitive enzyme-linked immunosorbent assay (icELISA) method for detecting multiple tadalafil-like adulterants was established. The icELISA showed a limit of detection (LOD), 50% inhibition concentration (IC50 ), and a working range of 0.004-0.396, 0.89-4.27, and 0.094-16.71 ng/ml for tadalafil, amino tadalafil, acetamino tadalafil, nortadalafil, and N-desmethyl ent-tadalafil, respectively. The spiked recoveries of tadalafil-like adulterants in samples ranged from 84.9% to 116.2%. The results of the icELISA and HPLC-MS/MS methods had a good correlation for real samples with the R2 of 0.9955. Specially, this work not only provided a convenient immunoassay method for measuring tadalafil-like adulterants in spirit drinks and dietary supplements in group-screening manner, but also suggested that softness was likely to be a general theory for rational hapten design. PRACTICAL APPLICATION: Rapid monitoring of tadalafil-like adulterants in food samples is very necessary and important for consumers, regulatory agencies, and the food industry.

Two-hour acute restraint stress facilitates escape behavior and learning outcomes through the activation of the Cdk5/GR P S211 pathway in male mice.

Acute stress exerts pleiotropic actions on learning behaviors. The induced negative effects are sometimes adopted to measure the efficacy of particular drugs. Until now, there are no detailed experimental data on the time-gradient effects of acute stress. Here, we developed the time gradient acute restraint stress (ARS) model to precisely assess the roles of different restrain times on inducing acute stress. Time gradient ARS facilitates escape behaviors and learning outcomes, peaking at 2 h-ARS and then declining to baseline at 3.5 h-ARS as confirmed by time gradient post-stress data. Furthermore, time gradient ARS activates glucocorticoid receptor (GR) phosphorylation site at Serine211 (P S221) as an inverted V-shaped pattern peaking at 2 h-ARS, whereas that of the GR phosphorylation site at Serine226 (P S226) from 2 h-ARS to 3.5 h-ARS. The 2 h-ARS but not 3.5 h-ARS enhances synaptic plasticity and genes transcription associated with learning and memory in the hippocampus of male mice. The Cdk5 inhibitor, roscovitine, blocks this facilitation effect by intervening in GR phosphorylation at Serine211 in the 2 h-ARS mice. Altogether, these findings show that the time gradient ARS selectively activates GR phospho-isoforms and differentially influences the behaviors along with maintaining a relationship between 2 h-ARS and Cdk5/GR P S211-mediated transcriptional activity.

Comparison of Reproducibility of Linear Measurements on Digital Models among Intraoral Scanners, Desktop Scanners, and Cone-beam Computed Tomography

Purpose@#Intraoral scanners, desktop scanners, and cone-beam computed tomography (CBCT) are being used in a complementary way for diagnosis and treatment planning. Limited patient-based results are available about dimensional reproducibility among different three-dimensional imaging systems. This study aimed to evaluate dimensional reproducibility among patient-derived digital models created from an intraoral scanner, desktop scanner, and two CBCT systems. @*Materials and Methods@#Twenty-nine arches from sixteen patients who were candidates for implant treatments were enrolled. Different types of CBCT systems (KCT and VCT) were used before and after the surgery. Polyvinylsiloxane impressions were taken on the enrolled arches after the healing period. Gypsum casts were fabricated and scanned with an intraoral scanner (CIOS) and desktop scanner (MDS). Four test groups of digital models, each from CIOS, MDS, KCT, and VCT, respectively, were compared to the reference gypsum cast group. For comparison of linear measurements, intercanine and intermolar widths and left and right canine to molar lengths were measured on individual gypsum cast and digital models. All measurements were triplicated, and the averages were used for statistics.Bland–Altman plots were drawn to assess the degree of agreement between each test group with the reference gypsum cast group. A linear mixed model was used to analyze the fixed effect of the test groups compared to the reference group (α=0.05).Result: The Bland–Altman plots showed that the bias of each test group was –0.07 mm for CIOS, –0.07 mm for MDS, –0.21 mm for VCT, and –0.25 mm for KCT. The linear mixed model did not show significant differences between the test and reference groups (P>0.05). @*Conclusion@#The linear distances measured on the digital models created from CIOS, MDS, and two CBCT systems showed slightly larger than the references but clinically acceptable reproducibility for diagnosis and treatment planning.reproducibility for diagnosis and treatment planning.plots showed that the bias of each test group was –0.07 mm for CIOS, –0.07 mm for MDS,

Research on the prognosis of different types of microvessels in bladder transitional cell carcinoma.

BACKGROUND: At present, there is controversy on the role of microvessel density (MVD) in tumors as a prognostic indicator of bladder transitional cell carcinoma (BTCC). However, the MVD in tumors is simply classified based on the expression of several different vascular markers, which has not been related to analytical research on the prognosis of patients with BTCC. AIM: To explore the classification of blood vessels in tumors and studied the relationship between MVD and the prognosis of patients with BTCC. METHODS: The tissue mass was detected by tissue microarray and immunohistochemical analysis with monoclonal antibodies against CD31, CD34, CD105, and vascular smooth muscle actin to investigate the MVD in BTCC. The measurement data are expressed as the mean ± SD. The difference between the groups was analyzed by the t-test, the counting data were analyzed by χ 2 test. The Kaplan-Meier survival curve was estimated by the product-limit method. The log-rank time-series test was employed to compare the tumor-free survival curves. RESULTS: The MVD was closely related to the pathological grade, invasive depth, and prognosis of BTCC. Significant differences were found between grade I and grade II, grade II and grade III, superficial and invasive type, and the tumor-free survival group and the recurrence or metastasis group (P < 0.01). Multivariate analysis showed that undifferentiated MVD was an independent prognostic factor for patient survival time. An inverse correlation between undifferentiated tumor MVD and differentiated tumor MVD in BTCC was also shown. CONCLUSION: The classification of blood vessels in BTCC could act as an important prognostic indicator and may also be of great significance in the treatment of cancer.

Development of Time-Resolved Fluorescence Immunochromatographic Assays for Simultaneously Detecting Tylosin and Tilmicosin in Milk in Group-Screening Manner.

Tylosin and tilmicosin (T&T) residues in livestock products have received extensive attention from consumers. Time-resolved fluorescence immunochromatographic assay (TRFICA), as a fast, efficient and sensitive immunoassay method, has played an increasingly important role in the food safety field. Therefore, herein a quantitative and visual TRFICA was established for simultaneously detecting T&T in milk in a group-screening manner. Under the optimal conditions, the standard curve range of developed TRFICA based on the T&T was 1.87~7.47 ng/mL, and the half-maximal inhibition concentrations (IC50) were 4.06 ng/mL and 3.74 ng/mL, respectively. The limits of detection (LOD) of the TRFICA method were from 1.72 ng/mL to 1.39 ng/mL, and the visual cut-off values were 31.25 ng/mL and 62.50 ng/mL for T&T in milk, respectively. Moreover, the stability experiments showed that the strips could be stored at 4 °C for more than 6 months, the total detection time was less than 13 min, and the cross-reactivities (CRs) with related compounds were less than 0.1%, which concluded that the developed TRFICA method could be used in real milk sample detection.

Enhanced Non-Toxic Immunodetection of Alternaria Mycotoxin Tenuazonic Acid Based on Ferritin-Displayed Anti-Idiotypic Nanobody-Nanoluciferase Multimers.

The non-toxic immunoassay for mycotoxins is being paid more attention due to its advantages of higher safety and cost savings by using anti-idiotype antibodies to substitute toxins. In this study, with tenuazonic acid (TeA), a kind of highly toxic Alternaria mycotoxin as the target, an enhanced non-toxic immunoassay was developed based on the ferritin-displayed anti-idiotypic nanobody-nanoluciferase multimers. First, three specific ß-type anti-idiotype nanobodies (AId-Nbs) bearing the internal image of TeA mycotoxin were selected from an immune phage display library. Then, the AId-Nb 2D with the best performance was exploited to generate a nanoluciferase (Nluc)-functionalized fusion monomer, by which a one-step non-toxic immunodetection format for TeA was established and proven to be effective. To further improve the affinity of the monomer, a ferritin display strategy was used to prepare 2D-Nluc fusion multimers. Finally, an enhanced bioluminescent enzyme immunoassay (BLEIA) was established in which the half maximal inhibitory concentration (IC50) for TeA was 6.5 ng/mL with a 10.5-fold improvement of the 2D-based enzyme-linked immunosorbent assay (ELISA). The proposed assay exhibited high selectivities and good recoveries of 80.0-95.2%. The generated AId-Nb and ferritin-displayed AId-Nb-Nluc multimers were successfully extended to the application of TeA in food samples. This study brings a new strategy for production of multivalent AId-Nbs and non-toxic immunoassays for trace toxic contaminants.

SRC-1 Deficiency Increases Susceptibility of Mice to Depressive-Like Behavior After Exposure to CUMS.

Steroid receptor coactivator 1 (SRC-1) is one of the coactivators recruited by the nuclear receptors (NRs) when NRs are activated by steroid hormones, such as glucocorticoid. SRC-1 is abundant in hippocampus and hypothalamus and is also related to some major risk factors for depression, implicated by its reduced expression after stress and its effect on hypothalamus-pituitary-adrenal gland axis function. However, whether SRC-1 is involved in the formation of depression remains unclear. In this study, we firstly established chronic unpredictable stress (CUS) to induce depressive-like behaviors in mice and found that SRC-1 expression was reduced by CUS. A large number of studies have shown that neuroinflammation is associated with stress-induced depression and lipopolysaccharide (LPS) injection can lead to neuroinflammation and depressive-like behaviors in mice. Our result indicated that LPS treatment also decreased SRC-1 expression in mouse brain, implying the involvement of SRC-1 in the process of inflammation and depression. Next, we showed that the chronic unpredictable mild stress (CUMS) failed to elicit the depressive-like behaviors and dramatically promoted the expression of SRC-1 in brain of wild type mice. What's more, the SRC-1 knockout mice were more susceptible to CUMS to develop depressive-like behaviors and presented the changed expression of glucocorticoid receptor. However, SRC-1 deficiency did not affect the microglia activation induced by CUMS. Altogether, these results indicate a correlation between SRC-1 level and depressive-like behaviors, suggesting that SRC-1 might be involved in the development of depression induced by stress.

Development of a chemiluminescence immunoassay for detection of tenuazonic acid mycotoxin in fruit juices with a specific camel polyclonal antibody.

The natural mycotoxin tenuazonic acid (TeA) in foods is identified as the most toxic mycotoxin among the over 70 kinds of secondary toxic metabolites produced by Alternaria alternata. Some hapten-antibody-mediated immunoassays have been developed for TeA detection in food samples, but these methods show unsatisfactory sensitivity and specificity. In this study, a rationally designed hapten for TeA mycotoxin generated with computer-assisted modeling was prepared to produce a highly specific camel polyclonal antibody, and an indirect competitive chemiluminescence enzyme immunoassay (icCLEIA) was established with a limit of detection of 0.2 ng mL-1 under optimized conditions. The cross-reactivity results showed that several analogs and some common mycotoxins had negligible recognition by the anti-TeA polyclonal antibody. The average recoveries spiked in fruit juices were determined to be 92.7% with an acceptable coefficient of variation, and good correlations between icCLEIA and liquid chromatography tandem mass spectrometry (LC-MS/MS) results were obtained in spiked samples. This developed icCLEIA for TeA detection with significantly improved sensitivity and satisfactory specificity is a promising alternative for environmental monitoring and food safety.

Nanobody-Based Indirect Competitive ELISA for Sensitive Detection of 19-Nortestosterone in Animal Urine.

Nanobody (Nb), a new type of biorecognition element generally from Camelidae, has the characteristics of small molecular weight, high stability, great solubility and high expression level in E. coli. In this study, with 19-nortestosterone (19-NT), an anabolic androgenic steroid as target drug, three specific Nbs against 19-NT were selected from camel immune library by phage display technology. The obtained Nbs showed excellent thermostability and organic solvent tolerance. The nanobody Nb2F7 with the best performance was used to develop a sensitive indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) for 19-NT detection. Under optimized conditions, the standard curve of ic-ELISA was fitted with a half-maximal inhibitory concentration (IC50) of 1.03 ng/mL and a detection limit (LOD) of 0.10 ng/mL for 19-NT. Meanwhile, the developed assay had low cross- reactivity with analogs and the recoveries of 19-NT ranged from 82.61% to 99.24% in spiked samples. The correlation coefficient between ic-ELISA and the ultra-performance liquid chromatography/mass spectrometry (UPLC-MS/MS) method was 0.9975, which indicated that the nanobody-based ic-ELISA could be a useful tool for a rapid analysis of 19-NT in animal urine samples.

Development of Cu(II)/Cu(I)-induced quantum dot-mediated fluorescence immunoassay for the sensitive determination of ethyl carbamate.

A series of haptens were rationally designed for producing monoclonal antibodies specific for EC and a simple fluorescence immunoassay platform was developed for the sensitive determination of EC based on alkaline phosphatase (ALP)-triggered Cu+ quenching of CdSe quantum dots (QDs). It was noted that Cd as a fluorescence substrate in CdSe QDs can be selectively substituted by Cu+ that resulted in a more significant fluorescence quenching in comparison with Cu2+. Meanwhile, because ALP catalyzed ascorbic acid phosphate and then assisted the transformation of Cu2+ to Cu+, the change in fluorescence intensity was found to be proportional to ALP concentration. After simple magnetic separation, the sensitivity and linear range of the established assay were improved approximately 53-fold and an order of magnitude, respectively, when compared with the conventional ELISA. The proposed platform was able to both amplify the signal and eliminate matrix interferences, making it a promising to determine EC as well as other contaminants in complex food matrix in a highly sensitive and simple manner. Graphical abstract.

SRC-1 Knockout Exerts No Effect on Amyloid ß Deposition in APP/PS1 Mice.

Steroid receptor coactivator 1 (SRC-1) is the key coactivator because of its transcriptional activity. Previous studies have shown that SRC-1 is abundant in the hippocampus and has been implicated in cognition. SRC-1 is also related to some major risk factors for Alzheimer's disease (AD), such as a decline in estrogen and aging, however, whether SRC-1 is involved in the pathogenesis of AD remains unclear. In this study, we established SRC-1 knockout in AD mice by cross breeding SRC-1-/- mutant mice with APP/PS1 transgenic mice, and investigated the expression of some synaptic proteins, the amyloid ß (Aß) deposition, and activation of astrocytes and microglia in the hippocampus of APP/PS1×SRC-1-/- mice. The results showed that SRC-1 knockout neither affects the Aß plaque and activation of glia, nor changes the expression of synaptic proteins in AD model mice. The above results suggest that the complete deletion of SRC-1 in the embryo exerts no effect on the pathogenesis of APP/PS1 mice. Nevertheless, this study could not eliminate the possible role of SRC-1 in the development of AD due to the lack of observation of other events in AD such as tau hyperphosphorylation and the limitation of the animal model employed.