Advances in microfluidic-based DNA methylation analysis

DNA methylation has been extensively investigated in recent years,not least because of its known relationship with various diseases.Progress in analytical methods can greatly increase the relevance of DNA methylation studies to both clinical medicine and scientific research.Microflu-idic chips are excellent carriers for molecular analysis,and their use can provide improvements from multiple aspects.On-chip molecular analysis has received extensive attention owing to its advantages of portability,high throughput,low cost,and high efficiency.In recent years,the use of novel microfluidic chips for DNA methylation analysis has been widely reported and has shown obvious superiority to conventional methods.In this review,wefirst focus on DNA methylation and its applications.Then,we discuss advanced microfluidic-based methods for DNA methylation analysis and describe the great progress that has been made in recent years.Finally,we summarize the advantages that microfluidic technology brings to DNA methylation analysis and describe several challenges and perspectives for on-chip DNA methylation analysis.This review should help researchers improve their understanding and make progress in developing microfluidic-based methods for DNA methylation analysis.

An electrochemiluminescent magneto-immunosensor for ultrasensitive detection of hs-cTnI on a microfluidic chip

Sensitive detection and precise quantitation of trace-level crucial biomarkers in a complex sample matrix has become an important area of research.For example,the detection of high-sensitivity cardiac troponin I(hs-cTnI)is strongly recommended in clinical guidelines for early diagnosis of acute myocardial infarction.Based on the use of an electrode modified by single-walled carbon nanotubes(SWCNTs)and a Ru(bpy)32+-doped silica nanoparticle(Ru@SiO2)/tripropylamine(TPA)system,a novel type of electrochemiluminescent(ECL)magneto-immunosensor is developed for ultrasensitive detection of hs-cTnI.In this approach,a large amount of[Ru(bpy)3]2+is loaded in SiO2(silica nanoparticles)as luminophores with high luminescent efficiency and SWCNTs as electrode surface modification material with excellent elec-trooxidation ability for TPA.Subsequently,a hierarchical micropillar array of microstructures is fabricated with a magnet placed at each end to efficiently confine a single layer of immunomagnetic microbeads on the surface of the electrode and enable 7.5-fold signal enhancement.In particular,the use of transparent SWCNTs to modify a transparent ITO electrode provides a two-order-of-magnitude ECL signal amplifi-cation.A good linear calibration curve is developed for hs-cTnI concentrations over a wide range from 10 fg/ml to 10 ng/ml,with the limit of detection calculated as 8.720 fg/ml(S/N 3).This ultrasensitive immunosensor exhibits superior detection performance with remarkable sta-=bility,reproducibility,and selectivity.Satisfactory recoveries are obtained in the detection of hs-cTnI in human serum,providing a potential analysis protocol for clinical applications.

Effect of Velocity Ratio,Viscosity Ratio,Contact Angle,and Channel Size Ratio on Droplet Formation

This study uses a T-junction to examine the effects of different parameters(velocity ratio,viscosity,contact angle,and channel size ratio)on the generation of microdroplets,related rate,and size.More specifically,numerical simulations are exploited to investigate situations with a velocity varying from 0.004 to 1.6 m/s for the continuous phase and from 0.004 to 0.8 m/s for the dispersed phase,viscosity ratios(0.668,1,6.689,10,66.899),contact angle 80°<θ<270°and four different canal size ratios(1,1.5,2 and 4).The results show that canal size influences droplet size and the generation rate.The contact angle has an impact on the form and the quality of generated droplets.Moreover,the relationship between velocity and viscosity ratios,droplet size,and generation rate is non-monotonic.

Structural and functional studies of erythrocyte membrane-skeleton by single-cell and single-molecule techniques

As the indispensable oxygen-transporting cells,erythrocytes exhibit extreme deformability and amazing stability as they are subject to huge reversible shear stress and extrusion force during massive circulation in the body.The unique architecture of spectrin-actin-based membraneskeleton is considered to be responsible for such excellent mechanical properties of erythrocytes.Although erythrocytes have been recognized for more than 300 years,myriad questions about membrane-skeleton constantly attract people's attention.Here,we summarize the kinds of distinctive single-cell and single-molecule techniques that were used to investigate the structure and function of erythrocyte membrane-skeleton at macro and micro levels.

Recent Advances in Function-based Metagenomic Screening

Metagenomes from uncultured microorganisms are rich resources for novel enzyme genes. The methods used to screen the metagenomic libraries fall into two categories, which are based on sequence or function of the enzymes. The sequence-based approaches rely on the known sequences of the target gene families. In contrast, the function-based approaches do not involve the incorporation of metagenomic sequencing data and, therefore, may lead to the discovery of novel gene sequences with desired functions. In this review, we discuss the function-based screening strategies that have been used in the identi?cation of enzymes from metagenomes. Because of its simplicity, agar plate screening is most commonly used in the identi?cation of novel enzymes with diverse functions. Other screening methods with higher sensitivity are also employed, such as microtiter plate screening. Furthermore, several ultra-high-throughput methods were developed to deal with large metagenomic libraries. Among these are the FACS-based screening, droplet-based screening,and the in vivo reporter-based screening methods. The application of these novel screening strategies has increased the chance for the discovery of novel enzyme genes.

A Nano-and Micro-Integrated Protein Chip Based on Quantum Dot Probes and a Microfluidic Network

A novel nano-and micro-integrated protein chip(NMIPC)that can detect proteins with ultrahigh sensitivity has been fabricated.A microfl uidic network(μFN)was used to construct the protein chips,which allowed facile patterning of proteins and subsequent biomolecular recognition.Aqueous phase-synthesized,water-soluble fl uorescent CdTe/CdS core-shell quantum dots(aqQDs),having high quantum yield and high photostability,were used as the signaling probe.Importantly,it was found that aqQDs were compatible with microfluidic format assays,which afforded highly sensitive protein chips for cancer biomarker assays.

Integrated microfluidic devices for in vitro diagnostics at point of care

Given the continuous and growing demand for point of care(POC)diagnostic tests,attention has been shifted toward integration and miniaturization of laboratory protocols into“sample-in-answer-out”devices.Microfluidic technologies have been considered an ideal solution to address the requirements of POC diagnostics since many laboratory functions can be miniaturized and incorporated onto a single integrated chip.In this review,we summarize the advances of integrated microfluidic devices for POC diagnostics in the last 3 years.Particularly,we summarize current materials used for microfluidic chip fabrication,discuss the innovation of versatile integrated microfluidic devices,especially the strategies for simplifying sample preparation in manual or self-driven systems,and new detection methods of microfluidic chips.In addition,we describe new integrated microfluidic devices for POC diagnostics of protein-targeted immunodiagnostics,nucleic acid molecular tests,and small molecule metabolites analysis.We also provide future perspectives and current challenges for clinical translation and commercialization of these microfluidic technologies.