Complicated Sample Pretreatment Research Articles

Assessment of immunogenicity and drug activity in patient sera by flow-induced dispersion analysis

Biopharmaceuticals have revolutionized the treatment of many diseases such as diabetes, cancer, and autoimmune disorders. These complex entities provide unique advantages like high specificity towards their target. Unfortunately, biopharmaceuticals are also prone to elicit undesired immunogenic responses (immunogenicity), compromising treatment efficacy as well as patient safety due to severe adverse effects including life threatening conditions. Current immunogenicity assays are hampered by immobilization procedures, complicated sample pre-treatment, or rely on cell-based methods which all prevent reliable and continuous monitoring of patients. In this work, we present Flow Induced Dispersion Analysis (FIDA) for assessment of immunogenicity and drug activity in serum samples from arthritis patients receiving adalimumab. FIDA is a first principle technique for size-based characterization of biomolecules and their complexes under biologically relevant conditions. The FIDA methodology rely on an absolute and quantitative readout (hydrodynamic radius) thus reducing the need for positive and negative controls. Here, FIDA is applied for evaluating active adalimumab in serum by studying the interaction with its target tumor necrosis factor alpha (TNF-α). We report proof of principle for a quantitative approach for stratifying patients exhibiting presence of neutralizing and non-neutralizing antibodies based on their individual drug activity pattern. Further, it can be applied to any biopharmaceutical having soluble drug targets and it holds potential in a companion diagnostics setting.

In Situ Monitoring of Transmetallation in Electric Potential-Promoted Oxidative Coupling in a Single-Molecule Junction

In Situ Monitoring of Transmetallation in Electric Potential-Promoted Oxidative Coupling in a Single-Molecule Junction

DEOXYRIBOZYMES IN DETECTION OF PATHOGENIC BACTERIA

Aim. The purpose of the review was to analyze the use of DNAzyme biosensors for the detection of pathogens. In the recent years, deoxyribozymes (DNAzymes) have a significant impact as biosensors in diverse fields, from detection of metal ions in the environment to theranostic applications and detection of microorganisms. Although routinely used sophisticated instrumental methods are available to detect pathogenic bacterial contamination, they involve time-consuming, complicated sample pre-treatment and expensive instruments. As an alternative, pathogen-specific DNAzymes have demonstrated a series of advantages: a non-destructive rapid analysis technique with in situ and real-time detection of bacteria with high sensitivity and selectivity. A wide range of pathogen-specific DNAzymes has been developed using colorimetric and fluorescence-based detections for pathogenic bacterial contamination in various samples. The current review summarizes the in vitro selection of pathogen-specific DNAzymes, various strategies utilized in the sensor designs, and their potential use in theranostic applications.

SERS-ELISA determination of human carboxylesterase 1 using metal-organic framework doped with gold nanoparticles as SERS substrate.

By in situ synthesis of gold nanoparticles (AuNPs) within the acid-etched (AE) MIL-101 (Cr) framework, AE-MIL-101 (Cr) nanocomposites embedded with AuNPs (AuNP/AE-MIL-101 (Cr)) were prepared as surface-enhanced Raman scattering (SERS) substrate. AuNPs are uniformly distributed and stabilized inside the metal-organic framework (MOF), thus forming more SERS hotspots. The SERS performance of AuNP/AE-MIL-101 (Cr) was evaluated using 4-mercaptophenylboronic acid (4-MPBA), 4-mercaptobenzoic acid (4-MBA), benzidine, and rhodamine 6G (R6G). The SERS substrate displays satisfying stability with very low background signal. When benzidine is used as the Raman reporter, the limit of detection (LOD) can reach 6.7 × 10-13mol·L-1, and the relative standard deviation (RSD) of the intra- and inter-batch repetitive tests is less than 5.2%. On this basis, we developed a method for the detection of human carboxylesterase 1 (hCE 1) in human serum using AuNP/AE-MIL-101 (Cr) nanocomposite as SERS substrate and enzyme-linked immunosorbent assay (ELISA) colorimetric substrate as SERS marker. This method was used to determinehCE 1 in clinical serum samples without complicated sample pretreatment, and the detection results were consistent with the data determined by ELISA. In the concentration range 0.1-120 ng·mL-1, the SERS signal intensity of benzidine at 1609cm-1 gradually decreases with the increase of hCE 1 concentration (R2= 0.9948). The average recoveries of hCE 1 in human serum are in the range 84 to 108%, with RSDs lower than 7.7%. By using AuNP/acid etching-MIL-101(Cr) metal organic framework (MOF) as SERS substrate and enzyme-linked immunosorbent assay (ELISA) colorimetric substrate as the SERS marker, a rapid and sensitive method for the determination of human carboxylesterase 1 (hCE1) in human serum samples has been developed.

Facile Detection of Vitamin B12 with Copper Oxide Nanocrystal Graphenic Composite Electrode

Vitamin B12 (VB12) is applied as the cofactors in various important enzymatic reactions and is involved in gene expression regulation mediated by B12-riboswitch and the VB12-dependent photoreceptor. Rapid detection VB12 concertation in a given environment may provide insights in the evaluation of micronutrient levels and the physiological and ecological performances of organisms under the relevant condition. This study demonstrating an amperometric approach to quantify the VB12 in biological samples without complicated sample pretreatment. The electrochemical oxidation step was conducted with a plain graphenic electrode to convert all nitrogen groups within the VB12 molecules to NO3− at 1.3 V vs. Ag/AgCl for 15 min. VB12 was quantified stoichiometrically according to the oxidized nitrate anions, which were reduced with copper oxide nanocrystal decorated graphenic electrode. Cathodic polarization was conducted with a graphite rod electrode before nitrate reduction to eliminate the potential interferences. Under optimized experimental conditions, the presented approach gave a wide detection linear range of 0.15–7378 nmol L−1 and the detection limit was 0.59 nmol L−1. The results for biological samples were comparable to those of the HPLC method. These results indicated that successively combined anodic and cathodic polarization enhanced the detection sensitivity and efficiency of the electrode towards VB12. The proposed electrode shows potential in terms of efficiency, reliability and accuracy for rapid determination of VB12 in biological samples.

Ultrasensitive colorimetric miRNA detection based on magnetic 3D DNA walker and unmodified AuNPs

Abstract Gold nanoparticles (AuNPs) based colorimetric assay is a promising platform for simple and low-cost point-of-care (POC) testing, but tends to have low sensitivity, which limits their clinical applications for trace nucleic acid assays. Herein, a simple colorimetric assay was developed by using unmodified AuNPs and magnetic 3D DNA walker, which could detect as few as 16.7 fM of miRNA-155, thus easily solves the main technical challenge of AuNPs-based colorimetric nucleic acid assays. In this platform, hundreds of substrate sing-stranded DNA (DNA tracks) and dozens of blocked walking strands were attached on an Au-Fe3O4 nanocomposite, applied as a magnetic 3D DNA walker. The target could activate this DNA walker powered by DNAzyme cleavage mechanism, generating a great deal of single-stranded product (displaced ssDNA). After magnetic separation, the generated displaced ssDNA (supernatant) was incubated with AuNPs to protect the unmodified nanoparticles from aggregation in high-salt solutions. Based on this, the concentration of miRNA-155 could be visualized through a color change from grayish black to purple and quantitatively determined by UV–vis spectroscopy. Furthermore, we demonstrated that our approach could be used to detect target miRNA-155 in real human serum samples without complicated sample pretreatment. Thus, the magnetic 3D DNA walker-AuNPs colorimetric method is a facile, sensitive and specific detection platform that shows great potential for development of next-generation POC nucleic acids diagnostics.

A Fluorescence Sensor for Pb2+ Detection Based on Liquid Crystals and Aggregation-Induced Emission Luminogens.

Heavy metals, such as lead ions, are regarded as the main environmental contaminants and have a negative impact on human bodies, making detection technologies of lead ions critical. However, most existing detection methods suffer from time consumption, complicated sample pretreatment, and expensive equipment, which hinder their broad use in real-time detection. Herein, we show a new fluorescence sensor for detecting lead ions derived from liquid crystals doped with an aggregation-induced emission luminogen. The mechanism is based on the variation of fluorescence intensity caused by the disturbance of an ordered liquid crystal configuration in the presence of Pb2+, induced by DNAzyme and its catalytic cleavage. The proposed fluorescence sensor exhibits a low detection limit of 0.65 nM, which is 2 orders of magnitude lower than that previously reported in an optical sensor based on liquid crystals. The detection range of the Pb2+ fluorescence sensor is broad, from 20 nM to 100 μM, and it also selects lead ions from numerous metal ions exactly, resulting in a highly sensitive, highly selective, simple, and low-cost detection strategy of Pb2+ with potential applications in chemical and biological fields. This approach to designing a liquid crystal fluorescence sensor offers an inspiring stage for detecting biomacromolecules or other heavy metal ions by varying decorated molecules.

Insights into chemometric algorithms for quality attributes and hazards detection in foodstuffs using Raman/surface enhanced Raman spectroscopy.

Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS) have been extensively explored in the design of accurate, transparent, and conclusive food safety and quality control assays. Its hyphenation with chemometric algorithms is instrumental in securing safe food campaigns. To provide valuable recommendations and meet the growing demands for food screening, the current study begins with a brief description of the Raman spectroscopy and SERS theory followed by a comprehensive overview of spectral preprocessing, qualitative algorithms, variable selection methods, and quantitative algorithms. The review emphasizes on the importance of food monitoring practices using multivariate regression models. The applicability of the distinct chemometrics modes toward monitoring pesticide, food and illicit additives, heavy metals, pathogens, and its metabolites in Raman spectroscopy and SERS is covered in dairy, poultry, oil, honey, beverages, and other selected food matrices. Its pertinence toward classification and/or discrimination in food quality and safety monitoring and authentication is examined. Finally, it also complies with the limitations, key challenges, and prospects. The chemometrics processing spectra implemented with simpler or no complicated sample pretreatment step make Raman spectroscopy/SERS technique a potential approach that is expected to achieve simultaneous and fast detection of multiple analytes in food matrices.

Development of glucose oxidase-chitosan immobilized paper biosensor using screen-printed electrode for amperometric detection of Cr(VI) in water.

Hexavalent chromium is a toxic heavy metal getting discharged into the environment and water bodies through various industrial processes. Conventional analysis methods call for expensive equipment and complicated sample pretreatment that made unsuitable for onsite detection. Paper is used as an enzyme immobilization platform because of its property to wick the liquid by capillary action; lightweight, cheap and can be easily patterned or cut according to the requirements for developing biosensor. In this study, enzyme immobilization of glucose oxidase (GOx) on filter paper were examined using three polysaccharides such as chitosan, sodium alginate and dextran for entrapment efficiency, activity and stability of the immobilized enzyme. Among the three, chitosan proved efficient for enzyme entrapment with about 90% efficiency at 0.3% (w/v) chitosan. The stability was checked after 1week at 4°C and room temperature, where the chitosan entrapped enzyme retained nearly 97% stability at 4°C. Enzyme inhibition study of GOx and Cr(VI) was carried out using chronoamperometry shown uncompetitive type of inhibition. A paper-based electrochemical biosensor strip was developed by immobilizing GOx enzyme on filter paper using chitosan as an entrapping agent and associating it with a screen-printed carbon electrode for amperometric measurements. The linear range of detection was obtained as 0.05-1ppm with the limit of detection as 0.05ppm for Cr(VI), which is the standard permissible limit in potable water. The relative standard deviation (5.6%) indicates good reproducibility of the fabricated biosensor.

Ionophore-Based Ion-Selective Nanospheres Based on Monomer-Dimer Conversion in the Near-Infrared Region.

Here, we report ion-selective nanospheres with readout in the near-infrared (NIR) region in both fluorescence and absorbance modes. The nanospheres rely on an ionophore-mediated monomer-dimer conversion of an NIR transducer, DTTC. The DTTC monomer in the nanospheres emits fluorescence around 820 nm, while the dimer in the aqueous environment generates strong blue-shifted emission around 660 nm. With a lead ionophore, an unprecedented lower detection limit of 3 pM for Pb2+ was achieved, allowing us to determine Pb2+ levels in river water without diluting the sample. Also, the Cu2+-selective nanospheres showed a detection limit of 5 nM. Taking advantage of the biologically desired NIR window, blood potassium concentrations were also determined without a complicated sample pretreatment. The sensing process was explained with a theoretical model. The detection range was found finely adjustable by the amount of nanospheres used. Therefore, the nanospheres formed a highly selective, sensitive, versatile, and rapid analytical platform for metal-ion sensing.

Methods and applications of single-cell proteomics analysis based on mass spectrometry

细胞是生命体的最小组成单位,遗传及外部环境等因素使单细胞异质性广泛存在于众多生物体中。传统的生物学实验获得的结果多是大量细胞的平均测量值,因此在单细胞层面开展研究对于精确理解细胞的生长发育以及疾病的诊断与治疗至关重要。而作为重要的细胞和生命活动的执行者,蛋白质由于其不具备扩增特性,且种类繁多、丰度低、动态分布范围宽,与核酸等其他生物大分子相比,其单细胞组学研究相对滞后。而在所有的检测手段中,荧光检测以及电化学分析方法具有极高的灵敏度,但是囿于其研究通量有限,以及电化学活性依赖,很难成为普适性的单细胞蛋白质组学研究方法。质谱分析作为传统蛋白质组学中最为核心的研究技术,由于其高灵敏、高通量、结构信息丰富等特点,在单细胞蛋白质组学研究中独树一帜。该文综述了近年来基于质谱的单细胞蛋白质组学研究中的代表性方法,根据质谱分析前蛋白质分离方式的差异,将其分为基于毛细管电泳分离、液相色谱分离和无分离手段的直接检测3类方法,在介绍研究现状的同时对这些方法在细胞通量、蛋白质鉴定数目、灵敏度以及方法应用方面进行了总结与比较。最后,基于目前研究中面临的挑战以及发展趋势对基于质谱的单细胞蛋白质组学的研究前景进行了展望。

A review of rapid pesticide residues determination in vegetables and fruits


 With the increasing demand of production, pesticides have been widely used in fruit and vegetable yield. Pesticides are used to kill insects, fungi and other organisms that harm the growth of crops in order to ensure and promote the growth of crops. In particular, pesticides are used to control diseases and insects and regulate plant growth and weeding. From the point at this stage, the use of pesticides in agricultural production is inevitable, and the corresponding, also in rapid increase in the amount of pesticide, pesticide residue problem is along with the production and extensive use of pesticides, pesticide, especially the organic pesticide used in great quantities, cause serious problems of pesticide pollution, a serious threat to human health. That is the abuse of pesticides does harm for environment and human health, particularly in the bioaccumulation effect of pesticide residues on human body, attracting more and more attention from scientists. Therefore, it’s imperative to develop high sensitivity, high selectivity, simple, rapid and low-cost methods for pesticide residues detection and analysis. The traditional methods of pesticide residue analysis mainly include gas chromatography high performance liquid chromatography, chromatography-mass spectrometry, etc. These methods have been widely used in pesticide residue detection, and a series of important achievements have been made. Although with high detection sensitivity, these methods have some problems such as complicated sample pretreatment, expensive equipment, time-consuming analysis, and the need for specialized instrument operators and so on, which cannot meet the requirements of rapid and real-time field detection of pesticide residues. Therefore, researchers in various fields have carried out and strengthened the research on rapid detection technology of pesticide residues, seeking to develop convenient, sensitive, accurate and stable new pesticide residue detection technology. In this paper, we mainly reviewed the rapid detection technologies of pesticide in fresh fruits and vegetables in recent years, including new chromatographic analysis, enzyme inhibition, fluorescence sensor, spectrophotometric and biosensor detection technology, and analyzed the development status, advantages, and disadvantages of each method, as well as the development prospect of rapid detection technology in the future.

Tailoring molecular permeability of vertically-ordered mesoporous silica-nanochannel films on graphene for selectively enhanced determination of dihydroxybenzene isomers in environmental water samples

Herein we demonstrate a simple and rapid electrochemical method for selectively enhanced determination of catechol (CC) or hydroquinone (HQ) isomers in environmental water samples by tailoring the molecular permeability of vertically-ordered mesoporous silica-nanochannel films on electrochemically reduced graphene oxide (VMSF/ErGO). Such VMSF/ErGO composite film was fabricated on the gold electrode (AuE) surface using electrochemically assisted self-assembly approach. The as-prepared electrodes with surfactant micelles (SM) template inside silica nanochannels, designed as SM/VMSF/ErGO/AuE, possess hydrophobic hydrocarbon cores and show preferential response to CC via hydrophobic effect. After removing SM from silica nanochannels, the obtained VMSF/ErGO/AuE displays more sensitive response to HQ, which is due to the hydrogen bond effect between the silanol groups of silica walls and HQ. Given the potential-resolved and high electrocatalytic ability of ErGO, and molecular permeability and anti-fouling ability of VMSF, these two present sensors could detect CC and HQ in lake water with a low limit of detection (18 nM for CC and 16 nM for HQ), and a high sensitivity (0.33 μA/μM for CC and 0.37 μA/μM for HQ), without complicated sample pretreatment. Moreover, the proposed sensors provide a convenient, rapid and economic way for direct analysis of environmental water samples, exhibiting excellent long-term stability.

SERS hydrogel pellets for highly repeatable and reliable detections of significant small biomolecules in complex samples without pretreatment

The detections of significant small molecules in biological fluids is always challenging due to the complicated sample pretreatment. Here, a universal SERS-hydrogel micropellet was developed for pretreatment-free, reliable detections of small molecules (glucose and melamine) in complex sample (whole blood and milk). The SERS-hydrogel micropellet has an adjustable pore size, which is acquired by the ultraviolet light solidification of the water-in-oil microdroplets in which the hydrogel monomers and the SERS-active metal nanoparticles (MNPs) were encapsulated. These micropellets have a pore size selectivity to allow small molecules to access in and exclude larger molecules, which is helpful for the highly selective, label-free/labeling SERS determinations of small molecules. This SERS substrate ensures high reproducibility of SERS detections since MNPs are uniformly dispersed in each micropellet. The hydrogel matrix can well protect MNPs from the surrounding environments to guarantee long-term stability. The lowest detectable concentration is 10 μM for glucose in whole blood and 10 nM for melamine in milk, and the linear ranges are 0.1-20 mM and 10-8-10-3 M, respectively. This method avoids the complicated preprocessing steps, requires a small volume of samples, has a fast response time and low-cost, which provides the possibility for multiplex SERS detections in liquid biopsy.

A Smartphone-Based Sensing System for On-Site Quantitation of Multiple Heavy Metal Ions Using Fluorescent Carbon Nanodots-Based Microarrays.

The development of cost-effective and versatile sensing system for simultaneous and rapid quantitation of multiple targets is highly demanded for environmental surveillance, food safety inspection, home healthcare, etc. This work reports on (1) paper-based microarrays relying on fluorescence turn-off of carbon nanodots (CDs) for analyte recognition and (2) a stand-alone smartphone-based portable reader (SBR) installed with a custom-designed APP (SBR-App), which can accurately and reproducibly acquire fluorescence change from the microarray chip, automatically report the results, generate and share the reports via wireless network. Simultaneous detection of Hg2+, Pb2+, and Cu2+ in the Pearl River water samples was achieved with the reported sensing system. End-user operation is limited to pipet samples to the microarray chip, insert the chip to the SBR, and open the SBR-App to acquire an image 5 min after sample introduction. There is no requirement for complicated sample pre-treatment and expensive equipment except for a smartphone. This versatile and cost-effective smartphone-based sensing system featured with reliability and simplicity is ideally suited for user- and eco-friendly point-of-need detection in resource-constrained environments.

A magnetic SERS immunosensor for highly sensitive and selective detection of human carboxylesterase 1 in human serum samples

Hepatocellular carcinoma (HCC) is a common and lethal cancer. New serum markers for detecting HCC are urgently needed. Human carboxylesterase 1 (hCE1) is an important member of the serine hydrolase superfamily and is closely related to the occurrence of HCC. It can be used as a good serum marker for early diagnosis of HCC. Here, we developed a surface enhanced Raman scattering (SERS)- based magnetic immunosensor that specifically recognizes and detects trace amounts of hCE1 in human serum via a sandwich structure consisting of a SERS tags, magnetic supporting substrates, and target antigen (hCE1). The SERS tags are 4-mercaptobenzoic acid (4-MBA)-labeled AgNPs, and the SERS supporting substrates are composed of a raspberry-like morphology of Fe3O4@SiO2@AgNPs magnetic nanocomposites surface-functionalized with a hCE1 antibody. The prepared SERS magnetic immunosensor exhibits excellent selectivity and extremely high sensitivity for hCE1 detection. The SERS signal and logarithm of hCE1 concentration presented a wide linear response range of 0.1 ng mL−1 to 1.0 mg mL−1, and the detection limit of hCE1 was 0.1 ng mL−1. The results indicate that the immunosensor can be used for the rapid determination of hCE1 in human serum without a complicated sample pre-treatment. Furthermore, the immunosensor has good reproducibility and stability, and has a promising prospect for the quantitative detection of other tumor markers in early clinical diagnosis.

Bioanalysis of Targeted Nanoparticles in Monkey Plasma via LC-MS/MS.

This work represents the first reporting of a comprehensive bioanalytical GLP methodology detailing the mass spectrometric quantitation of PF-05212384 dosed as a targeted polymeric encapsulated nanoparticle (PF-07034663) to monkeys. Polymeric nanoparticles are a type of drug formulation that enables the sustained release of an active therapeutic agent (payload) for targeted delivery to specific sites of action such as cancer cells. Through the careful design and engineering of the nanoparticle formulation, it is possible to improve the biodistribution and safety of a given therapeutic payload in circulation. However, the bioanalysis of nanoparticles is challenging due to the complexity of the nanoparticle drug formulation itself and the number of pharmacokinetic end points needed to characterize the in vivo exposure of the nanoparticles. Gedatolisib, also known as PF-05212384, was reformulated as an encapsulated targeted polymeric nanoparticle. The bioanalytical assays were validated to quantitate both total and released PF-05212384 derived from the encapsulated nanoparticle (PF-07034663). Assay performance calculated from quality control samples in three batch runs demonstrated intraday precision and accuracy within 10.3 and 12.2%, respectively, and interday precision and accuracy within 9.1 and 8.5%, respectively. This method leveraged automation to ease the burden of a laborious and complicated sample pretreatment and extraction procedure. The automated method was used to support a preclinical safety study in monkeys in which both released and total PF-05212384 concentrations were determined in over 1600 monkey plasma study samples via LC-MS/MS.

Highly Sensitive Chitosan and ZrO2 Nanoparticles-Based Electrochemical Sensor for 8-Hydroxy-2’-deoxyguanosine Determination

Background: 8-Hydroxy-2’-deoxyguanosine (8-OHdG) has been regarded as a typical stable biomarker of DNA oxidative damage, and its level is one of the criteria for early diagnosis of various diseases. Considering the significance of 8-OhdG, various analytical techniques have been used for assaying 8-OHdG but all of them suffer from basic limitations like highly expensive instrumentation, large amount of sample requirement, complicated sample pre-treatment, tedious and time-consuming procedures etc. However, electroanalytical sensors provide a faster, easy and sensitive means of analyzing. Methods: The chitosan (CS) film provided the high electrode activity and stability which is required for detecting 8-OHdG though direct electrochemical oxidation. Zirconia was employed because it has some unique properties, such as high redox activity and selectivity etc. High-performance composite was easily detected by differential pulse voltammetry at a working voltage of 0. 51 V (vs. Ag/AgCl). A rapid and sensitive electrochemical sensor based on CS and metal oxide nanocrystalline for the determination of 8-OHdG was established. Results: Under optimized experimental conditions, the peak currents of differential pulse voltammetry increased as the concentrations of 8-OHdG increased from 10 to 200 ng·mL-1. The detection limit was 3.67 ng·mL-1 which was calculated by the S/N ratio of 3. The recoveries of the real spiked samples are in the range between 93.2 to 105.3%. Conclusion: The electrochemical sensor for direct 8-OHdG determination using a new CS/zirconia composite for GCE modification was developed and showed excellent reproducibility, stability and sensitivity for the specific determination of 8-OHdG in real urine specimen.

A Simple 3D-Printed Enzyme Reactor Paper Spray Mass Spectrometry Platform for Detecting BuChE Activity in Human Serum.

To achieve personalized healthcare, a quick, accurate, and high-throughput method to detect disease biomarkers is essential. In the traditional practice, mass spectrometry is one of the most powerful tools and is widely studied. However, the test of human serum usually requires complicated sample pretreatment, tedious operations, and precise condition control, especially for the detection of enzymes as biomarkers. As butyrylcholinesterase (BuChE) has an indicative significance in detecting degenerative disease, liver injury, and organophosphate poisoning, the quick quantification of BuChE is of vital importance to the clinic. In this paper, we report the design and fabrication of a portable 3D-printed enzyme reactor paper spray cartridge (3D ER-PS) with integrated functions: temperature control, enzyme reaction, analyte transfer, and paper spray ionization. Coupled with mass spectrometry, quantitative testing of BuChE activity in human serum was realized conveniently and accurately. While it only requires very simple sample preparation, the results from current 3D ER-PS approach are well consistent with those obtained using Ellman's method. This 3D ER-PS platform not only provides a novel solution for the liquid biopsy of BuChE in clinics but also contributes to the development of quick and targeted medical approaches for analyzing other types of serum biomarker molecules in the field of disease diagnosis.

Self-Amplified Fluorescent Nanoparticles for Rapid and Visual Detection of Xylene in Aqueous Media.

Pollutant detection is of great importance for quality control of drinking water and environmental protection. The common methods of pollutant detection suffer from time-consuming procedures, bulky and expensive instruments, and complicated sample pretreatment. Herein, a type of conceptually new self-amplified fluorescent nanoparticle (SAFN) is constructed based on aggregation-induced emission (AIE) luminogens for rapid and visual detection of xylene in aqueous media. AIE luminogens are self-assembled into SAFNs in aqueous media, which emit efficiently due to the aggregation of luminogen molecules. The SAFNs of AIE luminogens stick xylene molecules from aqueous media through multiple interactions including hydrophobic and π-π interactions. Upon capturing xylene, SAFNs swell, which quench the fluorescence of the whole SAFNs, showing the self-amplification effect. Such a self-amplification effect is entirely different from that of conjugated polymers in the literature. Importantly, fluorescence quenching of SAFNs by xylene can be readily observed by the naked eye, which enables visual xylene sensing. The SAFNs enable rapid and visual detection of xylene in aqueous media with a low detection limit (5 μg/L) in the order of seconds. Given high sensitivity, rapid response, simple and easy operation, and low cost, SAFNs of AIE luminogens present a promising platform for visual detection of organic pollutants in aqueous media.