3D-printed electrochemical sensors: A new horizon for measurement of biomolecules

Electrochemical sensors are widely used to monitor biomolecules. However, limitations in sensor geometry have restricted the scope of currently used electrochemical sensors. 3D-printing has emerged as a promising manufacturing approach, to robustly make electrochemical sensors, that can stably measure in biological environments. This review highlights the recent trends in the development of 3D-printed electrodes and biosensors for measurement of biomolecules. Novel geometries of 3D-printed electrodes have provided the means to conduct ex vivo measurement in the intestinal tract and in vivo measurements in the brain. 3D-printing is providing the ability to manufacture electrochemical sensors that can measure biomolecules in diverse areas of the body.     

可用于多种生物分析的高性能芯片毛细管电泳系统

本文采用激光诱导荧光的检测方法,搭建出高灵敏度的双通道共聚焦芯片毛细管电泳的检测系统。采用湿法刻蚀玻璃的方法获得了芯片管道的模具,并采用浇铸法在聚二甲基硅氧烷上获得高质量的微管道。将聚二甲基硅氧烷和石英玻璃贴合成为毛细管电泳芯片,该电泳芯片散热性能良好,可重复使用。以Cy5荧光素为样品,经实验证明该系统的检出限为17 pmol/L,并能在高达1 200 V/cm的场强下正常运行(高压电源的最高输出电压为1 200 V/cm),最高理论塔板数超过106N/m,表明该系统具有较高电泳效率。将该系统应用于氨基酸和DNA片段的分离分析,以及生物素标记的DNA与链霉亲合素的相互作用的检测,获得了较好的实验结果,说明该系统能够有效地应用于多种生物分析中。     

Chiral separation on achiral stationary phases with different functionalities using β-cyclodextrin in the mobile phase and application to bioanalysis and coupled columns

Summary -cyclodextrin was used in the mobile phase as chiral selector for separating the enantiomers of terbutaline, chlorthalidone and oxazepam. The effect on chiral resolution using e.g. hydrophobic, polar or cation exchanging stationary phases was investigated. Both the chiral separation factor and retention level were affected by the concentration of methanol and -cyclodextrin. The stationary phase had no effect on the chiral separation only on the level of retention. By tuning the concentration of -cyclodextrin and methanol in the mobile phase chiral separation could be obtained on most stationary phases. By changing the stationary phase while adjusting the mobile phase composition to maintain the chiral selectivity, improvements of the selectivity towards e.g. endogenous compounds can be obtained when separating enantiomers in complex matrixes as biological fluids. Further improvement on selectivity can be obtained if coupled columns are used. This is examplified for separation of chlorthalidone and terbutaline enantiomers in biological fluids by coupling an achiral column to another achiral column and using a mobile phase containing -cyclodextrin on the last column.     

Fundamentals and bioanalytical applications of functional quantum dots as electrogenerated emitters of chemiluminescence

Since the electrochemiluminescence (ECL) of quantum dots (QDs) of silicon was reported by Science in 2002, lots of QDs (e.g., II-VI, III-V and IV-VI) with different sizes and shapes have been used as ECL emitters for bioanalysis. Especially, QDs functionalized with multitudinous biomolecules offer excellent ECL signal-transduction platforms for designing a new generation of biosensing devices.In this article, we focus on recent advances in the ECL principles of functional QDs, and their bioanalytical applications in DNA analysis, immunoassay, cytosensing and detection of other biological molecules.     

二维液相色谱在药物和毒物分析中的应用进展

生物样品中药物、毒物及内源性物质的定性与定量分析在生命科学和药物研发中发挥重要作用。生物样品的基质复杂,干扰物多,待测物浓度与内源性物质相比明显偏低,且样品取样量少,因此要求生物分析方法的特异性强、灵敏度高、重现性好。二维液相色谱技术具有峰容量大、显著降低复杂样品的基质效应和残留现象,及可以实现样品分析的自动化等特点,已成为生物样品分离分析的有力工具,在环境、食品和药物分析中得到广泛应用。本文在简要介绍了二维液相色谱原理装置基础上,对其在生物样品中药物、毒物和内源性物质分析中的应用进展进行了综述。     

Testing equivalence between two laboratories or two methods using paired-sample analysis and interval hypothesis testing

A modified interval hypothesis testing procedure based on paired-sample analysis is described, as well as its application in testing equivalence between two bioanalytical laboratories or two methods. This testing procedure has the advantage of reducing the risk of wrongly concluding equivalence when in fact two laboratories or two methods are not equivalent. The advantage of using paired-sample analysis is that the test is less confounded by the intersample variability than unpaired-sample analysis when incurred biological samples with a wide range of concentrations are included in the experiments. Practical aspects including experimental design, sample size calculation and power estimation are also discussed through examples.     

Nanomaterials in mass spectrometry ionization and prospects for biological application

The rapid development of nanotechnology has revolutionized scientific developments in recent decades. Mass spectrometry (MS) measurements are no exception and have benefited greatly from integration of nanomaterials in every step of analysis. This brief review summarizes recent developments in the field with the focus on the use of nanomaterials as alternative media to facilitate analyte ionization in laser-desorption ionization–mass spectrometry (LDI–MS) and secondary ion mass spectrometry (SIMS). The biological applications of both techniques are also detailed. The use of nanomaterials in other aspects of MS analysis, for example in sample clean-up and indirect analyte quantification, is briefly discussed.     

Impact of calibrator concentrations and their distribution on accuracy of quadratic regression for liquid chromatography–mass spectrometry bioanalysis

Despite the common use of quadratic regression in LC–MS bioanalysis, how calibrator concentrations should be determined is still vague. Both the number and concentrations of calibrators are usually selected arbitrarily to each one's preference. The purposes of this research were to evaluate the impact of calibrator concentrations and to find new approaches with improved accuracy and reduced cost for LC–MS bioanalysis. It was found for the first time that the lower and upper limits of quantitation plus their geometric mean are the three critical concentrations for quadratic regression. When different concentration ranges, different response precisions, and various degrees of downward quadratic responses were simulated, the best accuracy was obtained by including these critical concentrations and using fewer calibrator concentrations with more replicates per concentration, instead of using more calibrator concentrations in duplicate. In many cases, when the aforementioned three concentrations are used, as few as two replicates per concentration are enough for routine use and up to 20% of time and cost can be saved. Furthermore, downward quadratic response should be eliminated or reduced as much as possible and upper limit quality control must be included in each batch to monitor the accuracy at the high concentration end. The retrospective data analysis of published experimental results corroborates the aforementioned findings. Finally, the typical “concerns” and potential applications of the new quadratic regression approaches are discussed.     

Chemically-modified nanopores for sensing

Sensing with chemically-modified nanopores is an emerging field that is expected to have major impact on bioanalysis and fundamental understanding of nanoscale chemical interactions down to the single-molecule level. The main strength of nanopore sensing is that it implies the prospect of label-free single-molecule detection by taking advantage of the built-in transport-modulation-based amplification mechanism. At present, fabrication and application of solid-state nanopores are becoming the focus of attention because, compared with their biological counterparts, they offer greater flexibility in terms of shape, size, and surface properties, as well as superior robustness. A breakthrough in label-free nanopore sensing for real-world applications is therefore expected from implementing solid-state nanopores, an area that is still developing. Without claiming comprehensiveness, the focus of this review comprises recent results and trends in nanopore-based sensing (i.e. emerging technologies for fabricating solid-state nanopores, their chemical functionalization, and detection methods for quantitative analysis).     

Metal–Organic Framework-Based Artificial Organelle Corrects Microenvironment Interference for Accurate Intratumoral Glucose Analysis

Enzymatic catalysis with high efficiency allows them a great prospect in metabolite monitoring in living cells. However, complex tumor microenvironments, such as acidity, H₂O₂, and hypoxia, are bound to disturb catalytic reactions for misleading results. Here, we report a spatially compartmentalized artificial organelle to correct intratumoral glucose analysis, where the zeolitic imidazolate framework-8 immobilized glucose oxidase-horseradish peroxidase cascade core and catalase-directed shell act as signal transduction and guarding rooms respectively. The acid-digested core and stable shell provide appropriate spaces to boost biocatalytic efficiency with good tolerability. Notably, the endogenous H₂O₂ is in situ decomposed to O₂ by catalase, which not only overcomes the interference in signal output but also alleviates the hypoxic states to maximize glucose oxidation. The marked protective effect and biocompatibility render artificial organelles to correct the signal transduction for dynamic monitoring glucose in vitro and in vivo, achieving our goal of accurate intratumoral metabolite analysis.