Identification of prognostic biomarkers for cholangiocarcinoma by combined analysis of molecular characteristics of clinical MVI subtypes and molecular subtypes.

Cholangiocarcinoma (CCA) is widely noted for its high degree of malignancy, rapid progression, and limited therapeutic options. This study was carried out on transcriptome data of 417 CCA samples from different anatomical locations. The effects of lipid metabolism related genes and immune related genes as CCA classifiers were compared. Key genes were derived from MVI subtypes and better molecular subtypes. Pathways such as epithelial mesenchymal transition (EMT) and cell cycle were significantly activated in MVI-positive group. CCA patients were classified into three (four) subtypes based on lipid metabolism (immune) related genes, with better prognosis observed in lipid metabolism-C1, immune-C2, and immune-C4. IPTW analysis found that the prognosis of lipid metabolism-C1 was significantly better than that of lipid metabolism-C2 + C3 before and after correction. KRT16 was finally selected as the key gene. And knockdown of KRT16 inhibited proliferation, migration and invasion of CCA cells.

Insight into a Target-Induced Photocurrent-Polarity-Switching Photoelectrochemical Immunoassay for Ultrasensitive Detection of Escherichia coli O157:H7.

Sensitive, portable methods of detection for foodborne pathogens hold great significance for the early warning and prevention of foodborne diseases and environmental pollution. Restricted by a complicated matrix and limited signaling strategies, developing a ready-to-use sensing platform with ultrahigh sensitivity remains challenging. In this work, near-infrared (NIR) light-responsive AgBiS2 nanoflowers (NFs) and Cu2O nanocubes (NCs) were introduced to construct a novel target-induced photocurrent-polarity-switchable system and verified for the development of an all-in-one, ready-to-use photoelectrochemical (PEC) immunosensor. NIR-responsive n-type AgBiS2 NFs and p-type Cu2O NCs producing anodic and cathodic photocurrents were conjugated with monoclonal (MAb1) and polyclonal antibodies (PAb2), respectively. Using a sandwich-type immunocomplex bridged by Escherichia coli O157:H7, an efficient photocurrent-polarity-switching PEC system was formed on a paper-based working electrode (PWE). Owing to the spatial separation of the photogenerated carriers and the elimination of false-positive/negative signals by the polarity-switchable photocurrent, the proposed NIR PEC immunoassay for E. coli O157:H7 exhibits a considerably low detection limit of 8 colony-forming units/milliliter (CFU/mL) with a linear range from 25 to 5 × 107 CFU/mL. The platform includes a PWE with an automatic cleaning function and a portable PEC analyzer with smartphone-compatible Bluetooth capability, thus achieving point-of-care testing of E. coli O157:H7. The sensor was applied to the analysis of pork samples artificially contaminated with E. coli O157:H7, and the detection results were in good agreement with the plate counting method, a gold standard in the field. This work aimed to investigate the photoelectric activity of the NIR-responsive p/n-type composites and to provide a new signal-reversal route for the construction of an all-in-one ready-to-use PEC immunosensor for the detection of low-concentration biomolecules.

A Collection of RPA-Based Photoelectrochemical Assays for the Portable Detection of Multiple Pathogens.

Portable, ultrasensitive, and simultaneously quantitative detection of the nucleic acids of multiple foodborne pathogens is critical to public health. However, the current testing methods depend on costly equipment and tedious amplification steps. In this study, we propose a photoelectrochemical (PEC) biosensor combined with recombinase polymerase amplification (RPA) technology (RPA-PEC) for the rapid detection of multiple foodborne pathogens under irradiation of 980 nm light. In particular, two working surfaces were designed on homemade three-dimensional screen-printed paper-based electrodes. The genomic DNAs of Escherichia coli O157:H7 and Staphylococcus aureus was initiated by RPA on the corresponding electrode surfaces, thus forming a lab-on-paper platform. Using the formed DNA-PEC signaler, photocurrents were achieved at 37 °C after only 20 min of RPA. The detection performance was superior to that of conventional agarose gel electrophoresis, with detection limits of 3.0 and 7.0 copies/µL for E. coli O157:H7 and S. aureus, respectively. Our study pioneers a new RPA-PEC method for foodborne pathogens and provides directions for the construction of lab-on-paper platforms for the portable detection of multiple nucleic acids.

Pancreatic fistula and biliary fistula after laparoscopic pancreatoduodenectomy: 500 patients at a single institution.

Background: Pancreatic fistula (PF) and biliary fistula (BF) are two major leakage complications after pancreatoduodenectomy (PD). The aim of this study is to investigate the risk factors of PF and BF after laparoscopic PD (LPD). Materials and Methods: We conducted a retrospective analysis of 500 patients who underwent LPD from 1 April 2015 to 31 March 2020. Clinical data from patients were analysed using multivariate logistic regression analysis. Results: PF occurred in 86 (17.2%) patients. Univariate and multivariate analysis indicated that the soft texture of the pancreas (P = 0.001) was the independent risk factor for PF. BF occurred in 32 (6.4%) patients. Univariate and multivariate analysis indicated that history of cardiovascular disease (P < 0.001), surgical time (P = 0.005), pre-operative CA125 (P = 0.036) and pre-operative total bilirubin (P = 0.044) were independent risk factors for BF. Conclusion: The texture of the pancreas was an independent risk factor for PF after LPD, which was consistent with the literatures. In addition, history of cardiovascular disease, surgical time, pre-operative CA125 and pre-operative total bilirubin were new independent risk factors for BF after LPD. Therefore, patients with high-risk factors of BF should be informed that they are at a high risk for this complication.

An analysis of the effectiveness of stapler closure combined with a titanium clip in distal pancreatectomy.

PURPOSES: Postoperative pancreatic fistula is the most common and severe postoperative complication of distal pancreatectomy. Treatment of pancreatic stump to reduce the incidence of postoperative pancreatic fistula is crucial. This study evaluated the effectiveness of stapler closure combined with a titanium clip in distal pancreatectomy. METHODS: Prospectively collected data of consecutive patients who underwent distal pancreatectomy from April 2013 to May 2020 with pancreatic transection performed by the bare stapler method (131 patients), stapler + hand-sewn closure method (199 patients), and stapler + titanium clip method (209 patients) were reviewed retrospectively and compared between groups. RESULTS: No statistically significant differences were observed in basic data among the three groups. There were also no significant differences among the three groups in terms of the intraoperative data or tumor pathological types, except for the number of laparoscopic treatment cases (23, 53, and 80 for bare stapler method, stapler + hand-sewn closure method, and stapler + titanium clip method, respectively; P < 0.05) and pancreatic neuroendocrine tumor cases (15, 29, and 12, respectively; P < 0.05). There were no significant differences in postoperative complications or parameters, except for the number of clinical pancreatic fistula cases (31, 27, and 13 for bare stapler method, stapler + hand-sewn closure method, and stapler + titanium clip method, respectively; P < 0.05) and postoperative length of hospital stay (11.6 ± 8.3, 10.6 ± 9.7, and 9.3 ± 6.9 days, respectively; P < 0.05). The stapler + titanium clip group had a significantly lower number of clinical pancreatic fistula cases and shorter postoperative length of hospital stay than the other groups. The univariate analysis showed that pancreatic resection line thickness was an independent risk factor for clinical pancreatic fistula after operation. CONCLUSION: Stapler closure combined with titanium clips to reinforce the pancreatic stump is simple and easy to implement, effectively reduces the incidence of clinical pancreatic fistula, and shortens the postoperative length of hospital stay.

Prognostic validity of the American joint committee on cancer eighth edition staging system for well-differentiated pancreatic neuroendocrine tumors.

BACKGROUND: The American Joint Committee on Cancer (AJCC) made improvements for staging pancreatic neuroendocrine tumors (pNETs) in its 8th Edition; however, multicenter studies were not included. METHODS: We collected multicenter datasets (n = 1,086, between 2004 and 2018) to validate the value of AJCC 8 and other coexisting staging systems through univariate and multivariate analysis for well-differentiated (G1/G2) pNETs. RESULTS: Compared to other coexisting staging systems, AJCC 7 only included 12 (1.1%) patients with stage III tumors. Patients with European Neuroendocrine Tumor Society (ENETS) stage IIB disease had a higher risk of death than patients with stage IIIA (hazard ratio [HR]: 4.376 vs. 4.322). For the modified ENETS staging system, patients with stage IIB disease had a higher risk of death than patients with stage III (HR: 6.078 vs. 5.341). According to AJCC 8, the proportions of patients with stage I, II, III, and IV were 25.7%, 40.3%, 23.6%, and 10.4%, respectively. As the stage advanced, the median survival time decreased (NA, 144.7, 100.8, 72.0 months, respectively), and the risk of death increased (HR: II = 3.145, III = 5.925, and IV = 8.762). CONCLUSION: These findings suggest that AJCC 8 had a more reasonable proportional distribution and the risk of death was better correlated with disease stage.

Sirt3 promotes hepatocellular carcinoma cells sensitivity to regorafenib through the acceleration of mitochondrial dysfunction.

Regorafenib, a multiple kinase inhibitor, is recently approved for treatment of patients with advanced hepatocellular carcinoma (HCC). Previous studies demonstrated that regorafenib was a mitochondrial toxicant, which associated with the impairment of mitochondria. Sirt3 is involved in the regulation of mitochondrial function in cancers. This study aimed to investigate the mechanism of Sirt3 involved in the mitochondrial dysfunction which associated with regorafenib treatment in liver cancer cells. We found regorafenib inhibited Sirt3 and p-ERK expression in HCC cells in a dose-dependent manner. Bioinformatics analysis showed that Sirt3 expression was down-regulated in liver cancer tissues and its low expression was correlated with worse overall survival (OS) in liver cancer patients. After transfected with Sirt3 overexpression plasmid, we found that Sirt3 sensitized liver cancer cells to regorafenib and resulted in much more apoptosis with a significant increase of ROS level. However, exogenous antioxidant could not weaken the apoptosis. Mitochondrial membrane potential assay indicated that Sirt3 overexpression accelerated the mitochondrial depolarization process induced by regorafenib and aggravated mitochondrial injury. Cellular oxygen consumption assay showed that mitochondrial dysfunction was caused by the damage of the electron transport chain. The results demonstrated that Sirt3 overexpression promoted the increase of ROS and apoptosis induced by regorafenib through the acceleration of mitochondrial dysfunction by impairing function of the electron transport chain in liver cancer cells. Our studies verified the functional role of Sirt3 in regorafenib treatment and suggested that regorafenib accompanied with Sirt3 activator as a novel treatment strategy for HCC.

Analysis of flavor and taste attributes differences treated by chemical preservatives: a case study in strawberry fruits treated by 1-methylcyclopropene and chlorine dioxide.

Flavor and taste attributes of fruits varied by different preservatives treatments. Changes in sugars, organic acids, amino acids as well as volatiles of strawberries treated with 1-methylcyclopropene (1-MCP) and/or chlorine dioxide (ClO2) were evaluated during storage period in this study. Our results revealed that the decreases of tartaric acid, malic acid, citric acid, titratable acidity (TA), sucrose and soluble sugar contents were significantly inhibited by 1-MCP + ClO2. The fructose and glucose contents of all groups remained stable and slightly increased at the last period of 10 days. However, different treatments had no influence on content of succinic acid. Moreover, the highest sweet taste (77.37 mg 100 g-1 fresh weight) and lowest bitter taste (3.44 mg 100 g-1 fresh weight) free amino acids (FAA) were observed in the strawberries treated by 1-MCP combined with ClO2 treatment as compared to other treatments and control. (E)-2-hexenal was the most abundant volatile and showed a significant increase trend during strawberry storage. More interestingly, ethyl butyrate, fruit-like aroma, could be recovered in content by 1-MCP, ClO2 alone and their combination treatment. Compared with other treatments, the significant different flavor in ClO2 treatment was identified by principle component analysis. In addition, methyl hexanoate and 4-methoxy-2,5-dimethylfuran-3(2H)-one (DMMF) were the major factors that affected the volatile organic compounds (VOCs) of strawberries through the whole storage. Taken together, 1-MCP coupled with ClO2 could be a complex preservative to maintain strawberries quality by regulating the flavor and taste attributes.

Effect of chlorine dioxide (ClO2 ) on patulin produced by Penicillum expansum and involved mechanism.

BACKGROUND: Patulin, produced by Penicillium expansum in apple fruit, has side effects affecting human and animal health. The effect of chlorine dioxide (ClO2 ) on patulin production, and the mechanisms involved in this, were investigated. RESULTS: Patulin production by P. expansum was reduced by ClO2 treatment, both in apples and in a potato dextrose broth (PDB) medium, which was attributed to the antifungal effect of ClO2 , but not the direct reaction between ClO2 and patulin. Fumigation with ClO2 also significantly reduced disease development in apples infected with P. expansum, and inhibited mycelial growth and spore germination. After ClO2 treatment, P. expansum mycelial morphology was strongly affected, leading to the loss of plasma membrane integrity and causing cellular leakage. CONCLUSION: These data provide useful information that enables the inhibitory mechanism of ClO2 on patulin production by P. expansum to be better understood. It can also assist the development of effective methods to control patulin production in apples and other postharvest fruits. © 2018 Society of Chemical Industry.

Chlorine dioxide fumigation generated by a solid releasing agent enhanced the efficiency of 1-MCP treatment on the storage quality of strawberry.

The effect of 1-methylcyclopropene (1-MCP) and chlorine dioxide (ClO2) on fruit quality during storage was investigated. Strawberries were treated with 1-MCP alone or in combination with ClO2 gas generated by a releasing agent, and the quality, fruit decay, microbial inhibition, and enzyme activities [polyphenol oxidase (PPO), superoxide dismutase (SOD), ascorbate peroxidase (APX), and phenylalanine ammonia lyase (PAL)] at 4 °C were measured for 16 days. 1-MCP alone could maintain the fruit quality during storage but had little effect on microbial growth, resulting in quick decay during storage. ClO2 treatment effectively inhibited microbial growth during storage and improved shelf life with no visual damage. Moreover, 1-MCP in combination with ClO2 was superior in maintaining quality attributes as compared with 1-MCP alone, as significant differences were found in some indices. Furthermore, 1-MCP in combination with ClO2 maintained higher SOD, APX, and PAL activities and lower PPO activity as compared with the control and 1-MCP alone. Overall, ClO2 enhanced the effect of 1-MCP on strawberries during storage and shelf life, possibly through the inhibition of microbial growth and regulation of enzyme activity. The combination of 1-MCP and ClO2 may serve as a potential strategy with dual physiological and antimicrobial effects for the preservation of perishable products.

Safety and efficacy of RNAi therapy for transthyretin amyloidosis.

BACKGROUND: Transthyretin amyloidosis is caused by the deposition of hepatocyte-derived transthyretin amyloid in peripheral nerves and the heart. A therapeutic approach mediated by RNA interference (RNAi) could reduce the production of transthyretin. METHODS: We identified a potent antitransthyretin small interfering RNA, which was encapsulated in two distinct first- and second-generation formulations of lipid nanoparticles, generating ALN-TTR01 and ALN-TTR02, respectively. Each formulation was studied in a single-dose, placebo-controlled phase 1 trial to assess safety and effect on transthyretin levels. We first evaluated ALN-TTR01 (at doses of 0.01 to 1.0 mg per kilogram of body weight) in 32 patients with transthyretin amyloidosis and then evaluated ALN-TTR02 (at doses of 0.01 to 0.5 mg per kilogram) in 17 healthy volunteers. RESULTS: Rapid, dose-dependent, and durable lowering of transthyretin levels was observed in the two trials. At a dose of 1.0 mg per kilogram, ALN-TTR01 suppressed transthyretin, with a mean reduction at day 7 of 38%, as compared with placebo (P=0.01); levels of mutant and nonmutant forms of transthyretin were lowered to a similar extent. For ALN-TTR02, the mean reductions in transthyretin levels at doses of 0.15 to 0.3 mg per kilogram ranged from 82.3 to 86.8%, with reductions of 56.6 to 67.1% at 28 days (P<0.001 for all comparisons). These reductions were shown to be RNAi-mediated. Mild-to-moderate infusion-related reactions occurred in 20.8% and 7.7% of participants receiving ALN-TTR01 and ALN-TTR02, respectively. CONCLUSIONS: ALN-TTR01 and ALN-TTR02 suppressed the production of both mutant and nonmutant forms of transthyretin, establishing proof of concept for RNAi therapy targeting messenger RNA transcribed from a disease-causing gene. (Funded by Alnylam Pharmaceuticals; ClinicalTrials.gov numbers, NCT01148953 and NCT01559077.).

Tissue-specific gene silencing monitored in circulating RNA.

Pharmacologic target gene modulation is the primary objective for RNA antagonist strategies and gene therapy. Here we show that mRNAs encoding tissue-specific gene transcripts can be detected in biological fluids and that RNAi-mediated target gene silencing in the liver and brain results in quantitative reductions in serum and cerebrospinal fluid mRNA levels, respectively. Further, administration of an anti-miRNA oligonucleotide resulted in decreased levels of the miRNA in circulation. Moreover, ectopic expression of an adenoviral transgene in the liver was quantified based on measurement of serum mRNA levels. This noninvasive method for monitoring tissue-specific RNA modulation could greatly advance the clinical development of RNA-based therapeutics.

Ethylene inhibited sprouting of potato tubers by influencing the carbohydrate metabolism pathway.

The aim of this study was to investigate the role of ethylene to control sprouting of potatoes by observing the effect of exogenous ethylene on carbohydrate metabolism and key enzymes. The initial time of potato tuber sprouting and sprouting index were recorded, and rate of respiration, total sugar, total reducing sugar, starch, fructose, glucose, sucrose and the activities of acid invertase (AI), neutral invertase (NI), sucrose synthase (SS), sucrose phosphate synthase (SPS), starch phosphorylase and amylase during sprouting were measured. Exogenous ethylene inhibited sprouting of potato tubers. Moreover, exogenous ethylene increased respiration total sugar, AI activity, SPS activity, SS activity, and reduced sugar and assay activity. Nevertheless, starch, glucose, fructose, NI activity and starch phosphorylase activity showed lower variation. Lower sprouting resulted into potatoes with higher levels of total sugar, total reducing sugar and glucose, and lower level of fructose and sucrose. And sprouting could be inhibited by increasing the activities of SS, SPS and AI by treatment with 199.3 µl L-1 exogenous ethylene. Overall, exogenous ethylene inhibited sprouting of potato tubers by influencing its carbohydrate metabolism.

Rhizopus stolonifer and related control strategies in postharvest fruit: A review.

Rhizopus stolonifer is one of the main pathogens in postharvest storage logistics of more than 100 kinds of fruit, such as strawberries, tomatoes and melons. In this paper, the research on the morphology and detection, pathogenicity and infection mechanism of Rhizopus stolonifer was reviewed. The control methods of Rhizopus stolonifer in recent years was summarized from three dimensions of physics, chemistry and biology, including the nanomaterials, biological metabolites, light control bacteria, etc. Future direction of postharvest Rhizopus stolonifer infection control was analyzed from two aspects of pathogenic mechanism research and new composite technology. The information provided in this review will help researchers and technicians to deepen their understanding of the pathogenicity of Rhizopus stolonifer, and develop more effective control methods in the future.

An electrochemiluminescent dual-signal immunosensor based on a Ru(bpy)32+-doped silica nanoparticle/copper nanocluster composite for okadaic acid detection.

In this study, a sensitive dual-signal electrochemiluminescence (ECL) immunosensor was developed for okadaic acid (OA) detection utilizing copper nanoclusters (CuNCs) and Ru(bpy)32+-doped silica nanoparticles (RuSiNPs). Interestingly, the CuNCs could simultaneously enhance both cathodic (-0.95 V) and anodic (+1.15 V) ECL signals of RuSiNPs, forming a dual-signal ECL sensing platform. Further, RuSiNPs@CuNCs were used as immunomarkers by covalently conjugating them with an anti-OA monoclonal antibody (mAb) to form probes. Finally, dual ECL signals of the immunosensor were fabricated and showed good linear relationships with OA concentrations in the range of 0.05-70 ng mL-1, having a median inhibitory concentration (IC50) of 1.972 ng mL-1 and a limit of detection of 0.039 ng mL-1. Moreover, the constant ratio of the cathodic and anodic ECL peaks achieved self-calibration of the detection signal and improved the reliability of the results. Finally, we successfully applied the ECL sensor to detect OA in spiked oyster samples.

Ag@Au core-shell nanoparticle-based surface-enhanced Raman scattering coupled with chemometrics for rapid determination of chloramphenicol residue in fish.

The alarming increase in drug-resistant bacteria in fish resulting from the misuse of antibiotics poses a significant threat to ecosystems and human health. Therefore, the development of a reliable approach for detecting antibiotic residues in fish is crucial. In this study, a rapid and simple method for detecting chloramphenicol (CAP) residue in tilapia was developed using surface-enhanced Raman scattering (SERS) combined with chemometric algorithms. Silver and gold core-shell nanoparticles (Ag@Au CSNPs) were used as SERS nanosensors to achieve strong signal amplification with an enhancement factor of 2.67 × 106. The results demonstrated that the variable combination population analysis-partial least square (VCPA-PLS) model combined with the standard normal variable transformation pretreatment method exhibited the best predictive performance with a detection limit of 1 × 10-5 µg/mL. Thus, an SERS technique was established based on Ag@Au CSNPs combined with VCPA-PLS to rapidly detect CAP in tilapia.

Isothermal Reciprocal Catalytic DNA Circuit for Sensitive Analysis of Kanamycin.

Inappropriate use of veterinary drugs can result in the presence of antibiotic residues in animal-derived foods, which is a threat to human health. A simple yet efficient antibiotic-sensing method is highly desirable. Programmable DNA amplification circuits have supplemented robust toolkits for food contaminants monitoring. However, they currently face limitations in terms of their intricate design and low signal gain. Herein, we have engineered a robust reciprocal catalytic DNA (RCD) circuit for highly efficient bioanalysis. The trigger initiates the cascade hybridization reaction (CHR) to yield plenty of repeated initiators for activating the rolling circle amplification (RCA) circuit. Then the RCA-generated numerous reconstituted triggers can reversely stimulate the CHR circuit. This results in a self-sufficient supply of numerous initiators and triggers for the successive cross-invasion of CHR and RCA amplifiers, thus leading to exponential signal amplification for the highly efficient detection of analytes. With its flexible programmability and modular features, the RCD amplifier can serve as a universal toolbox for the high-performance and accurate sensing of kanamycin in buffer and food samples including milk, honey, and fish, highlighting its enormous promise for low-abundance contaminant analysis in foodstuffs.

Metal-organic framework-based multienzyme cascade bioreactor for sensitive detection of methyl parathion.

In this study, a cascade nanobioreactor was developed for the highly sensitive detection of methyl parathion (MP) in food samples. The simultaneous encapsulation of acetylcholinesterase (AChE) and choline oxidase (CHO) in a zeolitic imidazole ester backbone (ZIF-8) effectively improved the stability and cascade catalytic efficiency of the enzymes. In addition, glutathione-stabilized gold nanoclusters (GSH-AuNCs) were encapsulated in ZIF-8 by ligand self-assembly, conferring excellent fluorescence properties. Acetylcholine (ATCh) is catalyzed by a cascade of AChE/CHO@ZIF-8 as well as Fe(II) to generate hydroxyl radicals (·OH) with strong oxidizing properties. The ·OH radicals then oxidize Au(0) in GSH-AuNCs@ZIF-8 to Au(I), resulting in fluorescence quenching. MP, as an inhibitor of AChE, hinders the cascade reaction and thus restores the fluorescence emission, enabling its quantitative detection. The limit of detection of the constructed nanobioreactor for MP was 0.23 µg/L. This MOF-based cascade nanobioreactor has great potential for the detection of trace hazards.

Sulfadiazine detection in aquatic products using upconversion nanosensor based on photo-induced electron transfer with imidazole ligands and copper ions.

Contamination of aquatic products with sulfonamide antibiotics poses a threat to consumer health and can lead to the emergence of drug-resistant bacteria. Common methods to detect such compounds are slow and require expensive instruments. We developed a sensitive sulfadiazine (SDZ) detection method based on the photoinduced electron transfer between UCNPs and Cu2+. The surface-modified upconversion nanoparticles bind to Cu2+ by electrostatic adsorption, causing fluorescence quenching. The quenched fluorescence was subsequently recovered by the addition of imidazole and SDZ to the detection system, which formed a complex with Cu2+. The sensor showed excellent linearity over a wide concentration range (0.05-1000 ng/mL), had a low limit of detection (0.04 ng/mL), was selective, and was not affected by common substances present in aquatic media. This indicates that the sensor has great potential for application in the detection of SDZ residues in aquatic products.

Upconversion fluorescence nanosensor based on enzymatic inhibited and copper-triggered o-phenylenediamine oxidation for the detection of dimethoate pesticides.

Pesticide residues in agricultural products pose a significant threat to human health. Herein, a sensitive fluorescence method employing upconversion nanoparticles was developed for detecting organophosphorus pesticides (OPs) based on the principle of enzyme inhibition and copper-triggered o-phenylenediamine (OPD) oxidation. Copper ions (Cu2+) oxidized the colorless OPD to a yellow 2,3-diaminophenazine (oxOPD). The yellow solution oxOPD quenched the fluorescence of upconversion nanoparticles due to the fluorescence resonance energy transfer. The high affinity of Cu2+ for thiocholine reduced the level of oxOPD, resulting in almost no fluorescence quenching. The addition of dimethoate led to the inhibition of acetylcholinesterase activity and thus prevented the formation of thiocholine. Subsequently, Cu2+ oxidized OPD to form oxOPD, which attenuated the fluorescence signal of the system. The detection system has a good linear range of 0.01 ng/mL to 50 ng/mL with a detection limit of 0.008 ng/mL, providing promising applications for rapid detection of dimethoate.