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1.
Cancer biomarkers have significant potential as reliable tools for the early detection of the disease and for monitoring its recurrence. However, most current methods for biomarker detection have technical difficulties (such as sample preparation and specific detector requirements) which limit their application in point of care diagnostics. We developed an extremely simple, power-free microfluidic system for direct detection of cancer biomarkers in microliter volumes of whole blood. CEA and CYFRA21-1 were chosen as model cancer biomarkers. The system automatically extracted blood plasma from less than 3 μl of whole blood and performed a multiplex sample-to-answer assay (nano-ELISA (enzyme-linked immunosorbent assay) technique) without the use of external power or extra components. By taking advantage of the nano-ELISA technique, this microfluidic system detected CEA at a concentration of 50 pg/ml and CYFRA21-1 at a concentration of 60 pg/ml within 60 min. The combination of PnP polydimethylsiloxane (PDMS) pump and nano-ELISA technique in a single microchip system shows great promise for the detection of cancer biomarkers in a drop of blood.  相似文献   

2.
Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium resistant to all existing penicillin and lactam-based antimicrobial drugs and, therefore, has become one of the most prevalent antibiotic-resistant pathogens found in hospitals. The multi-drug resistant characteristics of MRSA make it challenging to clinically treat infected patients. Therefore, early diagnosis of MRSA has become a public-health priority worldwide. Conventionally, cell-culture based methodology and microscopic identification are commonly used for MRSA detection. However, they are relatively time-consuming and labor-intensive. Recently, molecular diagnosis based on nucleic acid amplification techniques, such as polymerase chain reaction (PCR), has been widely investigated for the rapid detection of MRSA. However, genomic DNA of both live and dead pathogens can be distinguished by conventional PCR. These results thus could not provide sufficient confirmation of an active infection for clinicians. In this study, live MRSA was rapidly detected by using a new integrated microfluidic system. The microfluidic system has been demonstrated to have 100% specificity to detect live MRSA with S. aureus and other pathogens commonly found in hospitals. The experimental results showed that the limit of detection for live MRSA from biosamples was approximately 102 CFU/μl. In addition, the entire diagnostic protocol, from sample pre-treatment to fluorescence observation, can be automatically completed within 2.5 h. Consequently, this microfluidic system may be a powerful tool for the rapid molecular diagnosis of live MRSA.  相似文献   

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4.
Cryptosporidiosis has been reported to be associated with HIV/acquired immune deficiency syndrome, which greatly reduces the quality of life and shortens the life expectancy of HIV-infected patients. In order to properly treat the infected patients, accurate and automatic diagnostic tools need to be developed. In this study, a novel microfluidic immunochip system was presented for the surveillance and the rapid detection of Cryptosporidium infection in 190 HIV-infected patients from Guangxi, China, using the P23 antigen of Cryptosporidium. The procedure of detection can be completed within 10 min with 2 μl sample consumption. The system also was evaluated using the standard ELISA method. Among 190 HIV-infected individuals, the rate of P23 positivity was 13.7%. Seropositivity in HIV-infected individuals was higher in female patients. The seropositivity to P23 was higher in HIV-infected individuals with high viral load, although the difference was statistically insignificant. Significantly higher Cryptosporidium seropositivity was observed in HIV-infected individuals with a CD4+ T-cell count of <200 cells/μl than in those with ≥200 cells/μl. Our results also demonstrate that a lower CD4+ T-cell count may reflect an increased accumulated risk for cryptosporidiosis. The detection system was further validated using the standard ELISA method and good correlation between the two methods was found (r = 0.80). Under the same sensitivity, this new microfluidic chip device had a specificity of 98.2%. This developed system may provide a powerful platform for the fast screening of Cryptospordium infection in HIV-infected patients.  相似文献   

5.
The emerging technologies on mobile-based diagnosis and bioanalytical detection have enabled powerful laboratory assays such as enzyme-linked immunosorbent assay (ELISA) to be conducted in field-use lab-on-a-chip devices. In this paper, we present a low-cost universal serial bus (USB)-interfaced mobile platform to perform microfluidic ELISA operations in detecting the presence and concentrations of BDE-47 (2,2′,4,4′-tetrabromodiphenyl ether), an environmental contaminant found in our food supply with adverse health impact. Our point-of-care diagnostic device utilizes flexible interdigitated carbon black electrodes to convert electric current into a microfluidic pump via gas bubble expansion during electrolytic reaction. The micropump receives power from a mobile phone and transports BDE-47 analytes through the microfluidic device conducting competitive ELISA. Using variable domain of heavy chain antibodies (commonly referred to as single domain antibodies or Nanobodies), the proposed device is sensitive for a BDE-47 concentration range of 10−3–104 μg/l, with a comparable performance to that uses a standard competitive ELISA protocol. It is anticipated that the potential impact in mobile detection of health and environmental contaminants will prove beneficial to our community and low-resource environments.  相似文献   

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7.
For the diagnosis of biochemical reactions, the investigation of microflow behavior, and the confirmation of simulation results in microfluidics, experimentally quantitative measurements are indispensable. To characterize the mixing and reaction of fluids in microchannel devices, we propose a mixing quality index (Mqi) to quantify the cross-sectional patterns (also called mixing patterns) of fluids, captured with a confocal-fluorescence microscope (CFM). The operating parameters of the CFM for quantification were carefully tested. We analyzed mixing patterns, flow advection, and mass exchange of fluids in the devices with overlapping channels of two kinds. The mixing length of the two devices derived from the analysis of Mqi is demonstrated to be more precise than that estimated with a commonly applied method of blending dye liquors. By means of fluorescence resonance-energy transfer (FRET), we monitored the hybridization of two complementary oligonucleotides (a FRET pair) in the devices. The captured patterns reveal that hybridization is a progressive process along the downstream channel. The FRET reaction and the hybridization period were characterized through quantification of the reaction patterns. This analytical approach is a promising diagnostic tool that is applicable to the real-time analysis of biochemical and chemical reactions such as polymerase chain reaction (PCR), catalytic, or synthetic processes in microfluidic devices.  相似文献   

8.
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9.
《Research Policy》2022,51(8):104143
The comparative advantage of a location shapes its industrial structure. Current theoretical models based on this principle do not take a stance on how comparative advantages in different industries or locations are related with each other, or what such patterns of relatedness might imply about the evolution of comparative advantage. We build a simple Ricardian-inspired model and show that hidden information on inter-industry and inter-location relatedness can be captured by simple correlations between the observed structure of industries across locations, or the structure of locations across industries. We then use this recovered information to calculate a measure of implied comparative advantage, and show that it explains much of the location’s current industrial structure. We give evidence that these patterns are present in a wide variety of contexts, namely the export of goods (internationally) and the employment, payroll and number of establishments across the industries of subnational regions (in the US, Chile and India). In each of these cases, the deviations between the observed and implied comparative advantage in the past tend to be highly predictive of future industry growth, especially at horizons of a decade or more; this explanatory power holds at both the intensive as well as the extensive margin. These results suggest that a component of the long-term evolution of comparative advantage is already implied in today’s patterns of production.  相似文献   

10.
Non-invasive and accurate access of biomarkers remains a holy grail of the biomedical community. Human eccrine sweat is a surprisingly biomarker-rich fluid which is gaining increasing attention. This is especially true in applications of continuous bio-monitoring where other biofluids prove more challenging, if not impossible. However, much confusion on the topic exists as the microfluidics of the eccrine sweat gland has never been comprehensively presented and models of biomarker partitioning into sweat are either underdeveloped and/or highly scattered across literature. Reported here are microfluidic models for eccrine sweat generation and flow which are coupled with review of blood-to-sweat biomarker partition pathways, therefore providing insights such as how biomarker concentration changes with sweat flow rate. Additionally, it is shown that both flow rate and biomarker diffusion determine the effective sampling rate of biomarkers at the skin surface (chronological resolution). The discussion covers a broad class of biomarkers including ions (Na+, Cl−, K+, NH4+), small molecules (ethanol, cortisol, urea, and lactate), and even peptides or small proteins (neuropeptides and cytokines). The models are not meant to be exhaustive for all biomarkers, yet collectively serve as a foundational guide for further development of sweat-based diagnostics and for those beginning exploration of new biomarker opportunities in sweat.  相似文献   

11.
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12.
This paper is concerned with the event-based weighted residual generator design via non-parallel distribution compensation (PDC) scheme for fault diagnosis in discrete-time T–S fuzzy systems, under consideration of the imperfect premise matching membership functions. An event-triggered mechanism is firstly introduced to save communication resources, which leads to the premise variables of the system and observer to be asynchronous. Then, a fuzzy diagnostic observer with mismatched premise variables is designed to estimate the unmeasurable states of the system. Moreover, by using non-PDC method, a diagnostic observer-based weighted residual generator is established to improve the fault detection (FD) performance by using the information provided by each local system, in which the membership functions structure of the diagnostic observer and residual generator need not to be the same as the systems, and the L∞/L2 and L∞ FD scheme is used to optimize the FD performance. Finally, two simulation results are provided to show the efficiency of the proposed non-PDC method.  相似文献   

13.
In the era of the targeted therapy identification of EGFR mutation detection in lung cancer is extremely helpful to predict the treatment efficacy of EGFR tyrosine kinase inhibitors (TKIs). Unfortunately, the inadequacy and quality of the biopsy samples are the major obstacles in molecular testing of EGFR mutation in lung cancer. To address this issue, the present study intended to use liquid biopsy as the non-invasive method for EGFR mutation detection. A total of 31 patients with an advanced stage of lung cancer were enrolled in the study from which cell-free DNA (cfDNA) and FFPE tissue DNA was extracted. Extracted DNA samples were analyzed for further EGFR exon specific mutation analysis by ARMS-PCR. Data were analyzed statistically using SPSS software. In cfDNA samples, the prevalence of wild type EGFR was 48% while the prevalence of TKI resistant and TKI sensitive mutations were 3%. Conversely, in tissue DNA samples, the prevalence of wild type, TKI sensitive and TKI resistant mutations were 48%, 19%, and 3%, respectively. The overall concordance of EGFR mutation between cfDNA and tissue DNA was 83%. McNemar’s test revealed that there was no significant difference between EGFR expression of cfDNA and tissue DNA samples. Additionally, the significant-high incidence of TKI resistant mutations was observed in tobacco habituates, indicating the role of carcinogens present in the tobacco in developing resistant mutations. In conclusion, our data suggest that evaluation of EGFR mutation from cfDNA samples is practicable as a non-invasive tool in patients with advanced-stage of lung cancer.  相似文献   

14.
Genetic sequence and hyper-methylation profile information from the promoter regions of tumor suppressor genes are important for cancer disease investigation. Since hyper-methylated DNA (hm-DNA) is typically present in ultra-low concentrations in biological samples, such as stool, urine, and saliva, sample enrichment and amplification is typically required before detection. We present a rapid microfluidic solid phase extraction (μSPE) system for the capture and elution of low concentrations of hm-DNA (≤1 ng ml−1), based on a protein-DNA capture surface, into small volumes using a passive microfluidic lab-on-a-chip platform. All assay steps have been qualitatively characterized using a real-time surface plasmon resonance (SPR) biosensor, and quantitatively characterized using fluorescence spectroscopy. The hm-DNA capture/elution process requires less than 5 min with an efficiency of 71% using a 25 μl elution volume and 92% efficiency using a 100 μl elution volume.  相似文献   

15.
We present an integrated microfluidic device capable of performing single-stranded DNA (ssDNA) preparation and magnetic bead-based microarray analysis with a white-light detection for detecting mutations that account for hereditary hearing loss. The entire operation process, which includes loading of streptavidin-coated magnetic beads (MBs) and biotin-labeled polymerase chain reaction products, active dispersion of the MBs with DNA for binding, alkaline denaturation of DNA, dynamic hybridization of the bead-labeled ssDNA to a tag array, and white-light detection, can all be automatically accomplished in a single chamber of the microchip, which was operated on a self-contained instrument with all the necessary components for thermal control, fluidic control, and detection. Two novel mixing valves with embedded polydimethylsiloxane membranes, which can alternately generate a 3-μl pulse flow at a peak rate of around 160 mm/s, were integrated into the chip for thoroughly dispersing magnetic beads in 2 min. The binding efficiency of biotinylated oligonucleotides to beads was measured to be 80.6% of that obtained in a tube with the conventional method. To critically test the performance of this automated microsystem, we employed a commercial microarray-based detection kit for detecting nine mutation loci that account for hereditary hearing loss. The limit of detection of the microsystem was determined as 2.5 ng of input K562 standard genomic DNA using this kit. In addition, four blood samples obtained from persons with mutations were all correctly typed by our system in less than 45 min per run. The fully automated, “amplicon-in-answer-out” operation, together with the white-light detection, makes our system an excellent platform for low-cost, rapid genotyping in clinical diagnosis.  相似文献   

16.
We present details of an apparatus for capacitive detection of biomaterials in microfluidic channels operating at microwave frequencies where dielectric effects due to interfacial polarization are minimal. A circuit model is presented, which can be used to adapt this detection system for use in other microfluidic applications and to identify ones where it would not be suitable. The detection system is based on a microwave coupled transmission line resonator integrated into an interferometer. At 1.5 GHz the system is capable of detecting changes in capacitance of 650 zF with a 50 Hz bandwidth. This system is well suited to the detection of biomaterials in a variety of suspending fluids, including phosphate-buffered saline. Applications involving both model particles (polystyrene microspheres) and living cells—baker’s yeast (Saccharomyces cerevisiae) and Chinese hamster ovary cells—are presented.  相似文献   

17.
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18.
We present an analytic technique for probing protein-catalyzed transient DNA loops that is based on nanofluidic channels. In these nanochannels, DNA is forced in a linear configuration that makes loops appear as folds whose size can easily be quantified. Using this technique, we study the interaction between T4 DNA ligase and DNA. We find that T4 DNA ligase binding changes the physical characteristics of the DNA polymer, in particular persistence length and effective width. We find that the rate of DNA fold unrolling is significantly reduced when T4 DNA ligase and ATP are applied to bare DNA. Together with evidence of T4 DNA ligase bridging two different segments of DNA based on AFM imaging, we thus conclude that ligase can transiently stabilize folded DNA configurations by coordinating genetically distant DNA stretches.  相似文献   

19.
We present an immunoaggregation assay chip for multiplexed biomarkers detection. This chip is based on immunoaggregation of antibody functionalized microparticles (Ab-MPs) to quantify concentrations of multiple biomarkers simultaneously. A mixture of multiple types of Ab-MPs probes with different sizes and magnetic properties, which were functionalized by different antibodies, was used for the multiplexed assay. The interactions between biomarkers and their specific Ab-MPs probes caused the immunoaggregation of Ab-MPs. A two-stage micro resistive pulse sensor was used to differentiate and count the Ab-MP aggregates triggered by different biomarkers via size and magnetic property for multiplexed detection. The volume fraction of each type of Ab-MP aggregates indicates the concentration of the corresponding target biomarker. In our study, we demonstrated multiplexed detection of two model biomarkers (human ferritin and mouse anti-rabbit IgG) in 10% fetal bovine serum, using anti-ferritin Ab and anti-mouse IgG Ab functionalized MPs. We found that the volume fraction of Ab-MP aggregates increased with the increased biomarker concentrations. The detection ranges from 5.2 ng/ml to 208 ng/ml and 3.1 ng/ml to 5.12 × 104 ng/ml were achieved for human ferritin and mouse anti-rabbit IgG. This bioassay chip is able to quantitatively detect multiple biomarkers in a single test without fluorescence or enzymatic labeling process and hence is promising to serve as a useful tool for rapid detection of multiple biomarkers in biomedical research and clinical applications.  相似文献   

20.
This paper investigates the problem of event-triggered fault detection filter design for nonlinear networked control systems with both sensor faults and process faults. First, Takagi–Sugeno (T–S) fuzzy model is utilized to represent the nonlinear systems with faults and disturbances. Second, a discrete event-triggered communication scheme is proposed to reduce the utilization of limited network bandwidth between filter and original system. At the same time, considering network-induced delays and event-triggered scheme, a novel T–S fuzzy fault detection filter is constructed to generate a residual signal, which has nonsynchronous premise variables with the original T–S fuzzy system. Then, the fuzzy Lyapunov functional based approach and the reciprocally convex approach are developed such that the obtained sufficient conditions ensure that the fuzzy fault detection system is asymptotically stable with H∞ performance and is less conservative. All the conditions are given in terms of linear matrix inequalities (LMIs), which can be solved by LMI tools in MATLAB environment. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed results.  相似文献   

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