荧光核酸适配体功能化氧化石墨烯生物传感器用于快速检测氯霉素

开发了一种无标记和快速的检测方法基于氧化石墨烯（GO）和荧光功能性G-四聚体探针（FGP），可用于定量检测氯霉素（CAP）.FGP由氯霉素核酸适配体和富含G碱基的核酸序列组成.核酸适配体用于结合CAP，并且由富含G碱基的核酸序列在K⁺，Na⁺离子的作用下形成的G-四聚体，然后与硫磺素T（ThT）结合后用作信号分子.在没有CAP的情况下，FGP通过π-π堆积相互作用被吸附到GO的表面上，阻碍了G-四聚体的形成导致溶液中的荧光强度低.在加入CAP时，FGP的核酸适配体部分可识别并结合CAP以形成复合物，导致其从GO解吸.因此，游离的富含G的碱基序列可以形成G-四聚体结构并与ThT结合，导致溶液的荧光强度增加.我们观察到荧光强度增加与CAP浓度在2~20 nmol/L范围内呈线性关系，检测限为1.45 nmol/L.此外，该检测系统用于检测加标牛奶中的CAP，回收率在93.2%~103.3%之间.这些结果表明，开发的方法可用于有效检测实际样品中的CAP.     

Aptamer Molecular Beacon Sensor for Rapid and Sensitive Detection of Ochratoxin A

Ochratoxin A (OTA) is a carcinogenic fungal secondary metabolite which causes wide contamination in a variety of food stuffs and environments and has a high risk to human health. Developing a rapid and sensitive method for OTA detection is highly demanded in food safety, environment monitoring, and quality control. Here, we report a simple molecular aptamer beacon (MAB) sensor for rapid OTA detection. The anti-OTA aptamer has a fluorescein (FAM) labeled at the 5′ end and a black hole quencher (BHQ1) labeled at the 3′ end. The specific binding of OTA induced a conformational transition of the aptamer from a random coil to a duplex–quadruplex structure, which brought FAM and BHQ1 into spatial proximity causing fluorescence quenching. Under the optimized conditions, this aptamer sensor enabled OTA detection in a wide dynamic concentration range from 3.9 nM to 500 nM, and the detection limit was about 3.9 nM OTA. This method was selective for OTA detection and allowed to detect OTA spiked in diluted liquor and corn flour extraction samples, showing the capability for OTA analysis in practical applications.     

Enhanced Peroxidase‐Like Properties of Graphene–Hemin‐Composite Decorated with Au Nanoflowers as Electrochemical Aptamer Biosensor for the Detection of K562 Leukemia Cancer Cells

Graphene composites with hemin and gold nanoparticles show a better performance for hydrogen peroxide decomposition compared to that of the three components alone or duplex/hybrid complexes. Our previous studies showed that the morphology of the Au nanoparticles may greatly influence the catalytic activity of graphene‐family peroxidase mimics. Recently, we found that Au nanoflowers could grow in situ and form on the surface of hemin/RGO (reduced graphene oxide). The prickly morphology of this Au nanoflower brought a higher catalytic ability with enhanced kinetic parameters than traditional Au nanoparticles that showed a smooth surface. Therefore, based on this discovery, a smart electrochemical aptamer biosensor for K562 leukemia cancer cells was further presented with good performance in selectivity and sensitivity attributed to the excellent mimetic peroxidase catalytic activity of this newly synthesized Au nanoflower decorated graphene–hemin composite (H‐RGO‐Au NFs).     

Employing Label‐free Electrochemical Biosensor Based on 3D‐Reduced Graphene Oxide and Polyaniline Nanofibers for Ultrasensitive Detection of Breast Cancer BRCA1 Biomarker

A label‐free DNA biosensor based on three‐dimensional reduced graphene oxide (3D‐rGO) and polyaniline (PANI) nanofibers modified glassy carbon electrode (GCE) was successfully developed for supersensitive detection of breast cancer BRCA1. The results demonstrated that 3D‐rGO and PANI nanofibers had synergic effects for reducing the charge transfer resistance (R_ct), meaning a huge enhancement in electrochemical activity of 3D‐rGO‐PANI/GCE. Probe DNA could be immobilized on 3D‐rGO‐PANI/GCE for special and sensitive recognition of target DNA (1.0×10^?15–1.0×10^?7 M) with a theoretical LOD of 3.01×10^?16 M (3S/m). Furthermore, this proposed nano‐biosensor could directly detect BRCA1 in real blood samples.     

金属有机骨架材料-核酸适配体荧光法检测沙门氏菌

基于金属有机骨架材料(Uio-66-NH2)的荧光猝灭特性以及对核酸适配体的吸附性,结合核酸适配体的高亲和力与高特异性识别能力,构建了针对沙门氏菌检测的荧光生物传感器,当有荧光素修饰的沙门氏菌、适配体被材料吸附到表面时,由于材料诱导电子转移猝灭了荧光素的荧光,若溶液中存在沙门氏菌,则沙门氏菌与其适配体特异性结合后从材料表面脱附,材料与荧光素之间的电子转移过程被切断,荧光素的荧光恢复。基于此原理构建的荧光传感器的信号与沙门氏菌浓度的对数在101~105cfu/m L范围内呈良好的线性关系,检出限(S/N=3)为7 cfu/m L,将该方法用于虾肉样品中沙门氏菌的检测,加标回收率为90.0%~108.0%,该传感器对沙门氏菌有较好的选择性与灵敏度。     

基于适配体胶体金侧向层析试纸快速检测卡那霉素的方法研究

该文基于适配体以及非巯基化核酸修饰的胶体金纳米探针（AuNPs@polyA－DNA）,建立了一种新型的卡那霉素胶体金侧向层析试纸条。分析了试纸条各组装元件,包括适配体浓度、链霉亲和素（SA）与Biotin－DNAT的比例、SA－生物素（Biotin）－DNAT偶联物浓度以及孵育时间与温度等,对显色反应的影响。最佳实验条件为：缓冲液为4xSSC（0.5% Tween 20）,SA与Biotin－DNAT的最佳摩尔比为1∶6,检测区喷涂偶联物SA－Biotin－DNAT浓度为4 μmol/L,适配体浓度为10 nmol/L,室温孵育时间为20 min。在优化条件下,该试纸条对卡那霉素的肉眼分辨浓度为25 ng/mL,线性范围为5.0～125 ng/mL,检出限为1.5 ng/mL。用于蜂蜜中卡那霉素的检测,其回收率为95.1%～105%,相对标准偏差（RSD）为3.4%～8.5%。该试纸条具有灵敏度高、特异性好、架构简单、重复性高等优点,可用于实际样品中卡那霉素的检测。     

适配体生物传感器在黄曲霉毒素B1检测中的应用

该文首先对黄曲霉毒素B1（AFB1）的相关性质及其传统检测方法进行了介绍,随后概述了近年来基于光学、电化学以及微流控芯片的适配体生物传感器的构建及其在AFB1检测领域中的应用,旨为适配体生物传感器的实际应用提供参考;并通过探讨目前开发的检测方法存在的问题,对适配体生物传感器前景和未来趋势进行了展望。     

LED激发荧光光谱法快速测定玉米粉中的黄曲霉毒素B1

以LED灯为激发光源,小型光纤光谱仪为检测设备,构建了LED激发的荧光光谱检测装置,并基于Hg2+对黄曲霉毒素B1（AFB1）的荧光增强效应,建立了AFB1的荧光光谱快速定量分析方法。研究确定了激发波长为370 nm,荧光检测波长为443.2 nm,对Hg2+与AFB1反应的pH值、溶剂配比、反应时间等条件进行优化,同时探究了方法的干扰因素。在优化条件下,AFB1－Hg2+体系的荧光发射强度与AFB1的质量浓度在3～90 μg/L范围内呈线性关系,相关系数r2 = 0.996,检出限为0.913 μg/L。将该方法用于两种玉米粉中AFB1的检测,其加标回收率为84.1%～107%,相对标准偏差（RSD）为1.1%～7.1%。该研究为AFB1的快速检测提供了一种新的具有较高灵敏度、精密度的快速检测方法,有望在现场快速检测中得到应用。     

A Dual-Mode Method Based on Aptamer Recognition and Time-Resolved Fluorescence Resonance Energy Transfer for Histamine Detection in Fish

Histamine produced via the secretion of histidine decarboxylase by the bacteria in fish muscles is a toxic biogenic amine and of significant concern in food hygiene, since a high intake can cause poisoning in humans. This study proposed a fluorometric and colorimetric dual-mode specific method for the detection of histamine in fish, based on the fluorescence labeling of a histamine specific aptamer via the quenching and optical properties of gold nanoparticles (AuNPs). Due to the fluorescence resonance energy transfer phenomenon caused by the proximity of AuNPs and NaYF4:Ce/Tb, resulting in the quenching of the fluorescence signal in the detection system, the presence of histamine will compete with AuNPs to capture the aptamer and release it from the AuNP surface, inducing fluorescence recovery. Meanwhile, the combined detection of the two modes showed good linearity with histamine concentration, the linear detection range of the dual-mode synthesis was 0.2–1.0 μmol/L, with a detection limit of 4.57 nmol/L. Thus, this method has good selectivity and was successfully applied to the detection of histamine in fish foodstuffs with the recoveries of 83.39~102.027% and 82.19~105.94% for Trichiurus haumela and Thamnaconus septentrionalis, respectively. In addition, this method was shown to be simple, rapid, and easy to conduct. Through the mutual verification and combined use of the two modes, a highly sensitive, rapid, and accurate dual-mode detection method for the analysis of histamine content in food was established, thereby providing a reference for the monitoring of food freshness.     

适体荧光分析法检测养殖废水中四环素类抗生素

建立了核酸适体识别-荧光探针技术检测养殖废水中土霉素、四环素、金霉素及强力霉素4种四环素类抗生素(TCs)总残留量的新方法。两段DNA对TCs共同识别后折叠成稳定的"发卡型"双链结构,核酸染料4'-6-二脒基-2-苯基吲哚(DAPI)能插入"发卡"部位产生荧光信号发射,据此可实现对TCs的定量检测。在最优实验条件下,以土霉素为目标分子建立工作曲线,在10~50 nmol/L范围内,荧光强度与对应浓度呈良好线性关系,土霉素的检出限为2.3 nmol/L。用四环素、土霉素、金霉素和强力霉素分别进行加标回收实验,平均回收率为88.5%~102.3%,相对标准偏差(n=5)为3.2%~6.7%。5个养殖场水样中均有TCs检出,检出量在7.6~42.7 nmol/L之间。该方法简单、灵敏、快速,可满足养殖场废水中TCs总残留量的测定要求。     

Polyphenol-Enriched Blueberry Preparation Controls Breast Cancer Stem Cells by Targeting FOXO1 and miR-145

Scientific evidence supports the early deregulation of epigenetic profiles during breast carcinogenesis. Research shows that cellular transformation, carcinogenesis, and stemness maintenance are regulated by epigenetic-specific changes that involve microRNAs (miRNAs). Dietary bioactive compounds such as blueberry polyphenols may modulate susceptibility to breast cancer by the modulation of CSC survival and self-renewal pathways through the epigenetic mechanism, including the regulation of miRNA expression. Therefore, the current study aimed to assay the effect of polyphenol enriched blueberry preparation (PEBP) or non-fermented blueberry juice (NBJ) on the modulation of miRNA signature and the target proteins associated with different clinical-pathological characteristics of breast cancer such as stemness, invasion, and chemoresistance using breast cancer cell lines. To this end, 4T1 and MB-MDM-231 cell lines were exposed to NBJ or PEBP for 24 h. miRNA profiling was performed in breast cancer cell cultures, and RT-qPCR was undertaken to assay the expression of target miRNA. The expression of target proteins was examined by Western blotting. Profiling of miRNA revealed that several miRNAs associated with different clinical-pathological characteristics were differentially expressed in cells treated with PEBP. The validation study showed significant downregulation of oncogenic miR-210 expression in both 4T1 and MDA-MB-231 cells exposed to PEBP. In addition, expression of tumor suppressor miR-145 was significantly increased in both cell lines treated with PEBP. Western blot analysis showed a significant increase in the relative expression of FOXO1 in 4T1 and MDA-MB-231 cells exposed to PEBP and in MDA-MB-231 cells exposed to NBJ. Furthermore, a significant decrease was observed in the relative expression of N-RAS in 4T1 and MDA-MB-231 cells exposed to PEBP and in MDA-MB-231 cells exposed to NBJ. Our data indicate a potential chemoprevention role of PEBP through the modulation of miRNA expression, particularly miR-210 and miR-145, and protection against breast cancer development and progression. Thus, PEBP may represent a source for novel chemopreventative agents against breast cancer.     

基于磁性微球分离技术的核酸适体化学发光检测可卡因

设计了一种基于磁性微球与核酸适体的夹心式化学发光适体传感器,建立了高灵敏度的可卡因分析方法。实验考察了反应所用羧基磁性微球、捕获探针、可卡因适体、生物素标记的报告序列以及链霉亲合素修饰的辣根过氧化物酶用量对化学发光信号的影响。优化条件下,在1.0×10-8~1.0×10-4mol/L范围内,化学发光信号与可卡因浓度的对数呈线性相关(r2=0.989 7),检出限为3.2×10-9mol/L。考察了共存物质中适体对可卡因的特异性识别能力,方法显示了较好的选择性。     

A Simple Structure-Switch Aptasensor Using Label-Free Aptamer for Fluorescence Detection of Aflatoxin B1

Aflatoxin B1 (AFB1) is one of the mycotoxins produced by Aspergillus flavus and Aspergillus parasiticus, and it causes contamination in foods and great risk to human health. Simple sensitive detection of AFB1 is important and demanded for food safety and quality control. Aptamers can specifically bind to targets with high affinity, showing advantages in affinity assays and biosensors. We reported an aptamer structure-switch for fluorescent detection of aflatoxin B1 (AFB1), using a label-free aptamer, a fluorescein (FAM)-labeled complementary strand (FDNA), and a quencher (BHQ1)-labeled complementary strand (QDNA). When AFB1 is absent, these three strands assemble into a duplex DNA structure through DNA hybridization, making FAM close to BHQ1, and fluorescence quenching occurs. In the presence of AFB1, the aptamer binds with AFB1, instead of hybridizing with QDNA. Thus, FAM is apart from BHQ1, and fluorescence increases with the addition of AFB1. This assay allowed detection of AFB1 with a detection limit of 61 pM AFB1 and a dynamic concentration range of 61 pM to 4 μM. This aptamer-based method enabled detection of AFB1 in complex sample matrix (e.g., beer and corn flour samples).     

An ESIPT-Based Ratiometric Fluorescent Probe for Highly Sensitive and Rapid Detection of Sulfite in Living Cells

The novel ratiometric fluorescent probe HPQRB with an ESIPT effect based on Michael addition for highly sensitive and fast detection of sulfite in living HepG2 cells is reported. HPQRB can be easily synthesized by a two-step condensation reaction. HPQRB has a large emission shift (Δλ=116 nm), which is beneficial for fluorescence imaging research, and its sulfite-responsive site is based on a rhodamine-like structure with the emission peak at 566 nm, which decreases with increasing sulfite concentration. and its HPQ structure always has an ESIPT effect throughout the reaction process, keeping the emission peak at 450 nm as a self-reference. In particular, HPQRB has high selectivity for sulfite and responds quickly (within 30 s) with a low detection limit (44 nM). Furthermore, HPQRB has been successfully used for fluorescence imaging of sulfite in HepG2 cells, demonstrating the superior ability to detect sulfite under physiological conditions.     

基于铁氰化镍的非标记型核酸适配体电化学传感器检测凝血酶

在玻碳电极（GCE）表面首先用增敏作用的多壁碳纳米管(MWCNTs)夹心于两层电沉积的铁氰化镍（NiHCF）氧化还原电化学探针之间,然后以金纳米粒子为固定核酸适配体的载体,构建了检测凝血酶的非标记型核酸适配体生物传感器。 利用扫描电子显微镜(SEM)对MWCNTs和NiHCF的形貌进行了表征。 利用电化学阻抗谱对传感器的组装过程进行了监测,用循环伏安法（CV）和差分脉冲伏安法（DPV）对传感器的电化学行为进行了研究。 以铁氰化镍为探针的传感器对凝血酶的检测在1.0 ng/L~1.0 mg/L范围内呈良好的线性关系,相关系数为0.998,检测限为0.2 ng/L(S/N=3)。     

基于红色碳量子点的荧光法快速检测饮料中的胭脂红

该研究以红色碳量子点为荧光探针,建立了一种饮料中胭脂红的荧光快速检测方法,以满足食品着色剂胭脂红的检测需求.首先以对苯二胺为碳源,于180℃水热反应合成红色碳量子点(RCDs).研究发现所制备的RCDs的荧光发射峰与胭脂红的紫外可见吸收峰明显重叠,且两者之间存在内滤效应.基于内滤效应机理,建立了一种对胭脂红定量检测的荧...     

基于适体生物传感器的碱性磷酸酯酶化学发光检测腺苷

制备了一种可用于腺苷检测的适体生物传感器,以羧基磁性微球为载体,在其表面组装腺苷适体与地高辛修饰之腺苷适体互补的核酸短链,先加入一定浓度的腺苷,再连接抗地高辛的碱性磷酸酯酶,用化学发光法检测发光值,根据腺苷加入前后化学发光强度的变化来定量检测腺苷。实验考察了羧基磁性微球用量、氨基修饰的腺苷适体用量、地高辛修饰的核酸短链用量及抗地高辛的碱性磷酸酯酶用量对体系组装和腺苷识别的影响。结果显示,优化条件下,在1.0×10~(-7)~1.0×10~(-3)mol/L范围内,腺苷浓度的对数与发光信号呈线性关系(r~2=0.976 9),定量下限为1.0×10~(-7)mol/L。与其他核苷相比,腺苷的选择特异性更好,且在稀释血清中适体对腺苷有很好的特异性识别能力。