Flavor profiles of various Pyrus spp. cultivars exhibit significant variations, yet the underlying flavor-contributing factors remain elusive. In this investigation, a comprehensive approach encompassing metabolomics analysis, volatile fingerprint analysis, and descriptive sensory analysis was employed to elucidate the flavor disparities among Nanguoli, Korla fragrant pear, and Qiuyueli cultivars and uncover potential flavor contributor. The study comprehensively characterized the categories and concentrations of nonvolatile and volatile metabolites, and 925 metabolites were identified. Flavonoids and esters dominated the highest cumulative response, respectively. Utilizing weighted correlation network analysis (WGCNA), seven highly correlated modules were identified, yielding 407 pivotal metabolites. Further correlation analysis of the differential substances provided potential flavor constituents strongly associated with various sensory attributes; taste factors had a certain association with olfactory characteristics. Our findings demonstrated the manifestation of flavor was a result of the synergistic effect of various compounds; evaluation olfactory flavor necessitated a comprehensive consideration of taste substances.

In this study, we propose an interference-free SERS-based aptasensor for trace detection of chlorpyrifos (CPF) in real samples. In the aptasensor, gold nanoparticles coated with Prussian blue (Au@PB NPs) were employed as SERS tags to provide a sole and intense Raman emission at 2160 cm- 1, which could avoid overlapping with the Raman spectrum of the real samples in 600-1800 cm- 1 to improve the anti-matrix effect ability of the aptasensor. Under the optimum conditions, this aptasensor displayed a linear response for CPF detection in the range of 0.1-316 ng mL-1 with a low detection limit of 0.066 ng mL-1. In addition, the prepared aptasensor shows excellent application to determine CPF in cucumber, pear and river water samples. The recovery rates were highly correlated with high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS). This aptasensor shows interference-free, specific and sensitive detection for CPF and offers an effective strategy for other pesticide residue detection.

Realizing accurate pesticide multiresidue detection in a complex matrix is still a challenge for point-of-care sensing methods. Herein, we introduced background-free and multicolor aptasensors based on bioorthogonal surface-enhanced Raman scattering (SERS) tags and successfully applied them to analyze multiple pesticide residues. The excellent anti-interference and multiplex capability are due to the application of three bioorthogonal Raman reporters involving 4-ethenylbenzenamine (4-EBZM), Prussian blue (PB) and 2-amino-4-cyanopyridine (AMCP) with alkynyl and cyano groups, which demonstrated apparent Raman shift peaks at 1993 cm-1, 2160 cm-1, and 2264 cm-1 in the biologically Raman-silent region, respectively. Ultimately, a detection range of 1-50 nM for acetamiprid, atrazine and malathion was achieved with detection limits of 0.39, 0.57 and 0.16 nM, respectively. The developed aptasensors were successfully used to determine pesticide residues in real samples. These proposed multicolor aptasensors offer an effective strategy for pesticide multiresidue detection with advantages of anti-interference, high specificity and high sensitivity.

Food safety is a critical issue that is closely related to people’s health and safety. As a simple, rapid, and sensitive detection technique, surface-enhanced Raman scattering (SERS) technology has significant potential for food safety detection. Recently, researchers have shown a growing interest in utilizing silent region molecules for SERS analysis. These molecules exhibit significant Raman scattering peaks in the cellular Raman silent region between 1800 and 2800 cm−1 avoiding overlapping with the SERS spectrum of biological matrices in the range 600–1800 cm−1, which could effectively circumvent matrix effects and improve the SERS accuracy. In this review, the application of silent region molecules-based SERS analytical technique for food safety detection is introduced, detection strategies including label-free detection and labeled detection are discussed, and recent applications of SERS analysis technology based on molecules containing alkyne and nitrile groups, as well as Prussian blue (PB) in the detection of pesticides, mycotoxins, metal ions, and foodborne pathogens are highlighted. This review aims to draw the attention to the silent region molecules-based SERS analytical technique and to provide theoretical support for its further applications in food safety detection.

To comprehensively understand the volatile compounds and assess the aroma profiles of different types of Pyrus ussuriensis Maxim. Anli, Dongmili, Huagai, Jianbali, Jingbaili, Jinxiangshui, and Nanguoli were detected via headspace solid phase microextraction (HS-SPME) coupled with two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC-TOFMS). The aroma composition, total aroma content, proportion and number of different aroma types, and the relative quantities of each compound were analyzed and evaluated. The results showed that 174 volatile aroma compounds were detected in various cultivars, mainly including esters, alcohols, aldehydes, and alkenes: Jinxiangshui had the highest total aroma content at 2825.59 ng/g; and Nanguoli had the highest number of aroma species detected at 108. The aroma composition and content varied among pear varieties, and the pears could be divided into three groups based on principal component analysis. Twenty-four kinds of aroma scents were detected; among them, fruit and aliphatic were the main fragrance types. The proportions of aroma types also varied among different varieties, visually and quantitatively displaying changes of the whole aroma of the different varieties of pears brought by the changes in aroma composition. This study contributes to further research on volatile compound analysis, and provides useful data for the improvement of fruit sensory quality and breeding work.

近年来,表面等离子体共振(Surface Plasmon Resonance,SPR)技术因具有可实时、动态监测SPR芯片上分子间相互作用的优点,而广泛应用于小分子传感检测领域.信号放大是小分子SPR传感器的重要研究内容,它决定小分子能否被检出及传感器灵敏度,因此信号放大技术对其发展非常重要.纳米金因其高电子密度、介电特性及易修饰等特性而用于多种传感器的信号放大.重点介绍近 5 年来纳米金在小分子SPR传感器方面的应用情况,旨在为小分子SPR传感器的进一步发展提供参考依据.

The clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated proteins (CRISPR/Cas) systems, regarded as "God's scissors", have recently received considerable attention in performing genome editing, transcriptional regulation and biosensor construction, benefiting from their adjustable mechanical properties, easy to operate and design, good biocompatibility, and the collateral cleavage activity. Since 2019, aptamers have been becoming an attractive star integrated into CRISPR/Cas systems as newly emerging molecular recognition elements and flexible signal transduction modules, with their significant advantages such as high sensitivity, remarkable specificity, in vitro synthesis, base -pairing, labeling and modification, and programmability capability. In this review, the recent progress of CRISPR/Cas system-based aptasensors (Cas-aptasensors) is comprehensively summarized including their design principles and superior applications. Firstly, we briefly introduce the essential features of aptamers and the CRISPR/Cas system and then outline the composition of Cas-aptasensors involving the Cas proteins, crRNA, reporter probes, as well as the target analytes and their specific aptamers. In detail, we emphasize their fabrication methods, bio-recognition mechanism, as well as the detection evaluation of four major Cas-aptasensors types of fluorescent, electrochemical, colorimetric, and upconversion luminescent resonance energy transfer, and other four novel Cas-aptasensors including inductively light -up RNA aptamer-based sensors coupled plasma mass spectrometry, resonance Rayleigh scattering, and surface-enhanced Raman scattering, along with. Finally, the challenges and future directions are concluded and depicted for aptamers, CRISPR/Cas systems, and their accelerating applications in Cas-aptasensors. This review is expected to inspire more researchers to have insight into Cas-aptasensors and to help to improve the bioanalytical efficiency and probability of success. (c) 2022 Published by Elsevier B.V.

为研究氟吗啉在辣椒中的残留消解情况及对居民的膳食摄入风险,本文采用高效液相色谱-串联质谱法测定氟吗啉在辣椒上的残留量,分析其消解动态规律.结果显示,氟吗啉在辣椒中的消解动态符合一级反应动力学方程,在浙江和湖南2个试验点的半衰期分别为3.4、4.1 d.氟吗啉在辣椒中的长期膳食摄入风险商为0.0138％;在所有登记作物中的总膳食摄入风险商为4.7219％.膳食风险评估结果表明,氟吗啉在辣椒中的残留对人群膳食风险在可接受范围内,按照推荐使用剂量、喷药次数及安全间隔期在辣椒上施用50％锰锌-氟吗啉可湿性粉剂,辣椒中的氟吗啉残留不会影响我国居民身体健康.

Lactoferrin (Lf), as a popular nutritional fortification in dairy products, has the ability regulate the body’s immune system and function as a broad-spectrum antibacterial, which is of great significance to the growth and development of infants and children. Herein, an indirect competitive enzyme-linked aptamer assay (ELAA) kit was established for rapid, sensitive, and visual determination of Lf in dairy products. In the construction, the Lf aptamer was conjugated with horseradish peroxidase (HRP) as the recognition probe and aptamer complementary strand (cDNA) were anchored onto the microplate as the capture probe. The recognition probes were first mixed with a sample solution and specifically bound with the contained Lf, then added into the microplate in which the free recognition probes in the mixture were captured by the capture probe. After washing, the remaining complex of cDNA/Aptamer/HRP in the microplate was conducted with a chromogenic reaction through HRP, efficiently catalyzing the substrate 3, 3′, 5, 5′-tetramethylbenzidine (TMB), therefore the color shade would directly reflect Lf concentration. Under the optimization conditions, a good linear relationship (R2, 0.9901) was obtained in the wide range of 25–500 nM with the detection limit of 14.01 nM and a good specificity, as well as the reliable recoveries. Furthermore, the ELAA kits achieved the Lf determination with an accuracy of 79.71~116.99% in eleven samples, which consisted of three kinds of dairy products: including goat milk powder, cow milk powder, and nutrition drop. Moreover, the results were also validated by the high-performance capillary electrophoresis (HPCE) method. The ELAA kit provides a simple and convenient determination for Lf in dairy products, and it is highly expected to be commercialized.

建立固相萃取-气相色谱-质谱(SPE-GC-MS)测定生姜中黄樟素及其衍生物的分析方法.样品经乙腈提取,氯化钠盐析后,采用PestiCarb/NH2柱净化,经DB-5MS毛细管色谱柱分离,选择离子监测模式(SIM)扫描测定,外标法定量.在0.01～1.0 μg/mL的线性范围内,黄樟素及其衍生物均成良好线性关系,相关系数(R2)均大于0.995,检出限为3.2～8.5 μg/kg;在50,100和500 μg/kg 3个添加水平下,回收率为89.8％～107.8％,相对标准偏差(SRSD,n=6)为1.8％～6.9％.该方法准确度高,回收率好,可用于生姜样品中黄樟素及其衍生物的定性及定量分析,为市场监管和实验室检测提供技术支持.

The enzyme-linked apta-sorbent assay (ELASA) is widely used for the detection of small-molecule compounds as a result of low cost and reagent stability of aptamers. However, enzyme labels used in ELASA still suffer from some drawbacks, such as high production cost and limited stability. To overcome the drawbacks, we reported a nanozyme-linked apta-sorbent assay (NLASA) coupled with surface-enhanced Raman scattering (SERS)-colorimetric dual-mode detection. For nanozyme labels, Pd-Pt bimetallic nanocrystals (Pd-Pt NRs) could catalyze 3,3',5,5'-tetramethylbenzidine (TMB) to blue TMB2+, whose color variation could not only be distinguished by naked eyes but also had a strong SERS signal. The NLASA method was employed to detect ochratoxin A (OTA) with a limit of detection values of 0.097 nM (0.039 ppb) and 0.042 nM (0.017 ppb) via the colorimetric and SERS methods, respectively. This method was applied for the determination of OTA in wine and grape samples, and the detection results were in a satisfied agreement with those determined by the high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method. The proposed NLASA method provided a rapid and sensitive detection for OTA and could also be broadened for other small-molecules.

Highly toxic pesticides are forbidden because of threatening to human lives, property, and the environment. However, some of them are still used illegally by added into normal pesticides to enhance the effectiveness and lower the cost. Therefore, it is very important to detect the illegally added ingredients in pesticides, such as Isofenphos-methyl in Tolfenpyrad. In this research, a rapid and accurate method for determining the concentration of Isofenphos-methyl in Tolfenpyrad is studied by near infrared spectroscopy with only nine characteristic wavelengths. Different pre-treating methods of direct orthogonal signal correction and first-order derivative on raw spectra and analysis methods of back propagation neural network and partial least squares are investigated to establish quantitative analysis models for comparison. Among them, the back propagation neural network model pre-treated with the direct orthogonal signal correction method has good prediction accuracy and prevents the data from being over-corrected. The correlation coefficients of the model calibration set and prediction set are as high as 0.999 and 0.989, respectively. Root Mean Square Error of Prediction and Ratio of Prediction to Deviation are 0.27% and 9.17, respectively. The prediction concentration limit can be as low as 0.5%. The results show that the direct orthogonal signal correction pre-treating method combined with back propagation neural network can be used for precisely quantitative determination of pesticide doping concentration. It provides an effective approach for rapid and accurate determination of prohibited components in pesticides.

近年来,表面增强拉曼光谱(surface enhancement Raman spectroscopy,SERS)标记技术因具有高灵敏度、可多路复用、强抗光漂白性和较好的分子指纹保真度等特性而备受瞩目,并已成功应用于传感分析及生物成像领域.本综述主要总结了基于SERS标记技术的生物传感器的原理及其在农药残留快速检测领域中的最新研究进展,重点介绍了SERS标签的设计与制备及基于不同识别元件传感系统的研究现状.同时,对其面临的挑战和解决方案进行了探讨,以期促进SERS标记技术在农药残留检测及食品安全检测方面的应用.

目的 建立气相色谱-串联质谱法(gas chromatography-mass spectrometry,GC-MS)测定韭菜中拟除虫菊酯类农药残留的分析方法.方法 样品采用QuEChERS处理,经乙腈提取,氯化钠盐析后,采用N-丙基乙二胺(primary secondary amine,PSA)净化,浓缩定容后用GC-MS在选择离子监测模式(select ion monitoring,SIM)下进行测定,外标法定量.结果 7种拟除虫菊酯农药在质量浓度0.01～1.0μg/mL范围内,线性关系良好,相关系数(r2)在0.9989～0.9995之间;检出限为0.6～3.0μg/kg.分别向韭菜样品中加入标准品0.01、0.1、0.5 mg/kg时,加标平均回收率为85.4％～102.4％,相对标准偏差(n=6)为1.8％～6.1％.结论 该方法简便快速、灵敏度好、准确度高,可用于韭菜样品中拟除虫菊酯类农药残留的测定.

[目的]建立测定甲氧虫酰肼在番茄上残留的高效液相色谱检测方法.[方法]样品经过酸化的甲醇高速匀浆提取,经过二氯甲烷萃取,采用甲醇:乙腈:水(30:55:15,V/V)为流动相,利用symmetry C18柱(4.0 mm×250 mm)进行检测.[结果]在0.01、0.50、2.00 mg/kg 3个添加浓度水平下,甲氧虫酰肼在番茄上的回收率为85％～105％,相对标准偏差(RSD)为0.6％～1.4％.相关系数(r)为0.9998.甲氧虫酰肼在番茄上的最低检出限为0.01 mg/kg,最小检出量为2 ng.在实际样品检测中检测出有甲氧虫酰肼的残留,但均未超过我国规定的最大残留限量值.[结论]在实际样品检测中,该方法能够快速、准确地对样品进行检测,为大量样品的检测提供了数据方法.

[目的]为确保4种农药在不同品种梨上的安全使用,评价其在梨上的消解趋势、残留水平,并且在2018年试验的基础上,验证毒死蜱、吡虫啉的安全使用评价标准及制定高效氯氟氰菊酯、多菌灵的安全使用评价标准.[方法]参考农药标签和梨果生产中调研的施药方法,选取全国6地的黄冠梨、莱阳梨、砂梨、早酥梨、砀山酥梨和鸭梨6个梨品种,开展田间试验.利用仪器分析方法,研究了毒死蜱、高效氯氟氰菊酯、吡虫啉、多菌灵在梨中的残留消解动态.[结果]4种农药在梨中的消解动态均满足一级反应动力学方程,半衰期分别为4.2、7.1、12.2、11.9 d.毒死蜱、吡虫啉的残留量及消解动态与2018年相比,较为吻合,年度差异不大,无超标现象.高效氯氟氰菊酯、多菌灵均有超标现象,多菌灵尤为突出.[结论]必须严格控制施药剂量及施药次数,并严格遵守安全间隔期.建议按照低剂量施药,每个作物周期最多施药3次,安全间隔期为21(高效氯氟氰菊酯)、28 d(多菌灵).按照推荐剂量及其操作规范在梨上施用是安全的.

应用气相色谱-离子迁移质谱对不同产地的翠冠梨果的香气指纹信息进行采集,通过主成分分析和相似度分析,判定香气之间的差异性,进而评价不同产地翠冠梨果的香气指纹信息、差异性及区分程度.经研究表明,6地翠冠梨中共鉴定香气物质43种,主要为酯类物质,也包括醇、醛、酮类物质;不同产地翠冠梨果中各类香气物质所占比例因梨果产地不同而不同;经统计分析确定受检梨果香气差异的主要贡献者,且以此可区分6地梨果.基于香气指纹差异性研究,可为梨果产地鉴别及溯源新方法开发提供理论依据和数据支持.

[目的]比较吡虫啉在大棚和露地蕹菜上的消解动态差异,为吡虫啉在蕹菜上的科学安全使用提供数据支持.[方法]采用QuEChERS-高效液相串联质谱法测定吡虫啉在大棚和露地上的残留量,分析其消解动态规律.在0.01～1 mg/kg添加水平下,吡虫啉的平均回收率为85％～103％,相对标准偏差(RSD)为3％～6％.[结果]吡虫啉在大棚和露地蕹菜中的消解动态均满足一级反应动力学方程,半衰期分别为3.50、2.29 d;在露地条件下吡虫啉药后10 d消解率达到95.11％,而大棚条件下药后21 d,消解率达到98.51％.[结论]露地条件下蕹菜中吡虫啉的原始沉积量及最终残留量均低于大棚,消解速率更快.

[目的]建立固相萃取-高效液相色谱-串联质谱(SPE-HPLC-MS/MS)同时测定梨中多抗霉素B和宁南霉素残留的分析方法.[方法]样品用0.2％甲酸水提取,经HLB和MCX固相萃取柱净化上机.用Waters ACQUITY UPLC BEH Amide色谱柱分离,以0.1％甲酸和0.1％甲酸乙腈溶液为流动相进行梯度洗脱,多反应离子监测模式(MRM)扫描,以基质匹配标准曲线外标法定量.[结果]多抗霉素B和宁南霉素在0.005～0.2 mg/L的质量浓度范围内均呈现良好的线性关系(R2＞0.999);在0.02、0.5、2.0 mg/kg的3个加标水平下,回收率为77％～91％,相对标准偏差(RSD)为2.8％～5.8％.[结论]该方法易于操作,灵敏度高,适用于梨中多抗霉素B和宁南霉素残留的同时检测.

The formation of self-assembled monolayers (SAMs) is a normal method for the immobilization of biorecognition elements immobilized on SPR sensors. With this method, mercaptopropionic acid (MPA) with carboxylic and thiol group is the most commonly used. Dimercaptosuccinic acid (DMSA) having two carboxylics and two thiol groups is a classical antidote for heavy metal ions. In this paper, DMSA was first used to form SAMs to connect the antigen on the chip of a surface plasmon resonance (SPR) immunosensor for detection of salbutamol (SAL), and the results were compared with a traditional (MPA)-SPR sensor. Dihydrolipoic acid(DHLA)-SPR showed that the recognition efficiency of antigen and antibody of DMSA-SPR immunosensor was 170.1% at room temperature with the linear range of 5–150 ng/mL. The recovery rate of this sensor applied to SAL detection in pork reached 94.9–108.0% and the limit of quantification (LOQ) was 5 ng/mL. The results were in good correlation with the analysis results of ultra-high phase liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis. This novel DMSA-SPR immunosensor provides insight into a new idea and method for improving the sensitivity of SPR immunosensors and can be widely used in the detection of other small molecules.