Microfluidic one-step, aqueous synthesis of size-tunable zeolitic imidazolate framework-8 for protein delivery

Zeolitic imidazolate framework-8(ZIF-8)with porous structure,biocompatibility,and pH-sensitive release behavior is a promising nanoplatform for protein delivery.However,it is still a challenging task for a practical synthesis of protein-loaded ZIF-8 nanoparticles.Here we report an all-aqueous microfluidic reactor for one-step,rapid,and highly controlled synthesis of ZIF-8 nanoparticles with high protein loading at room temperature.Microfluidic reactor allows for an ultrafast(<35 ms),complete mixing of Zn2+ions and 2-methylimidazole(2-MIM)at different molecular ratios,leading to the formation of stable ZIF-8 nanoparticles with tunable sizes(13.2–191.4 nm)in less than 30 s.By pre-mixing various proteins such as bovine serum albumin(BSA)(isoelectric point(pI)=5.82),ovalbumin(OVA)(pI=4.82),or RNase A(pI=8.93)with 2-MIM,ZIF-8 nanoparticles can be synthesized with protein encapsulation efficiency over 97%.Among the nanoparticles with different sizes,25 nm ZIF-8 nanoparticles show the best performance in promoting the cellular uptake of protein payload.Using OVA as a model protein,we demonstrate that 25 nm ZIF-8 nanoparticles significantly enhance the cytosolic delivery of antigen,as indicated by the effective activation of dendritic cells.We anticipate that this microfluidic synthesis of nanomaterials may advance the emerging field of cytosolic protein delivery.

A fully automated centrifugal microfluidic system for sample-to-answer viral nucleic acid testing

The outbreak of virus-induced infectious diseases poses a global public-health challenge.Nucleic acid amplification testing(NAAT)enables early detection of pandemic viruses and plays a vital role in preventing onward transmission.However,the requirement of skilled operators,expensive instrumentation,and biosafety laboratories has hindered the use of NAAT for screening and diagnosis of suspected patients.Here we report development of a fully automated centrifugal microfluidic system with sample-in-answer-out capability for sensitive,specific,and rapid viral nucleic acid testing.The release of nucleic acids and the subsequent reverse transcription loop-mediated isothermal amplification(RT-LAMP)were integrated into the reaction units of a microfluidic disc.The whole processing steps such as injection of reagents,fluid actuation by rotation,heating and temperature control,and detection of fluorescence signals were carried out automatically by a customized instrument.We validate the centrifugal microfluidic system using oropharyngeal swab samples spiked with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)armored RNA particles.The estimated limit of detection for armored RNA particles is 2 copies per reaction,the throughput is 21 reactions per disc,and the assay sample-to-answer time is approximately 70 min.This enclosed and automated microfluidic system efficiently avoids viral contamination of aerosol,and can be readily adapted for virus detection outside the diagnostic laboratory.

Nucleic acids analysis

Nucleic acids are natural biopolymers of nucleotides that store, encode, transmit and express genetic information, which play central roles in diverse cellular events and diseases in living things. The analysis of nucleic acids and nucleic acids-based analysis have been widely applied in biological studies, clinical diagnosis, environmental analysis, food safety and forensic analysis.During the past decades, the field of nucleic acids analysis has been rapidly advancing with many technological breakthroughs.In this review, we focus on the methods developed for analyzing nucleic acids, nucleic acids-based analysis, device for nucleic acids analysis, and applications of nucleic acids analysis. The representative strategies for the development of new nucleic acids analysis in this field are summarized, and key advantages and possible limitations are discussed. Finally, a brief perspective on existing challenges and further research development is provided.

An immunoassay based on lab-on-a-chip for simultaneous and sensitive detection of clenbuterol and ractopamine

Both clenbuterol(CLB)and ractopamine(RAC)areβ-adrenergic agonists.After long-term excessive intake,there will be adverse reactions such as headache,chest tightness,limb numbness,and serious lifethreatening.Simultaneous detection of CLB and RAC in related samples is of great importance for human health.In this work,we outline a microfluidics-based indirect competitive immunoassay(MICI)system that can sensitively detect residual CLB and RAC in pork,swine blood and swine urine.The rapid detection of multiple samples can be achieved in one chip,which greatly improves the detection efficiency.This method has good stability and reproducibility and the microfluidic chips are easy to manufacture.The linear ranges for CLB and RAC detection by MICI are 0.1-2.5 ng/mL and 0.1-5 ng/mL,and the limits of detection(LODs)are 0.094 ng/mL and 0.091 ng/mL,respectively.This straightforward and portable immunoassay system provides a good platform for rapid detection of harmful substances in food samples.

Microfluidic Separation,Detection,and Engineering of Extracellular Vesicles for Cancer Diagnostics and Drug Delivery

Extracellular vesicles(EVs)are cell-derived submicron bioparticles composed of lipid bilayer membrane and molecular cargos,acting as important mediators of physiopathological cellular processes.The analysis and engineering of EVs hold significant therapeutic potential in noninvasive cancer diagnostics and innovative drug delivery systems.Despite significant improvements in technologies for EV investigation,the clinical use of EVs has been hampered by several challenges including the requirement of expensive equipment such as ultracentrifuge for EV isolation from clinical samples,laborious and time-consuming procedures for EV analysis,and large batch-to-batch variation for EV engineering.In this respect,microfluidic technologies have attracted increasing attention as promising avenues to accelerate the study of EVs by offering advantages of small-volume capacity,cost effectiveness,precise manipulation of bioparticles,streamlined workflows,high levels of sensitivity and specificity,and good reproducibility and stability.In this Account,we review the state-of-the-art advances in the development of microfluidic platforms for EV separation,detection,and engineering with key applications in cancer diagnostics and drug delivery.We first elaborate a variety of passive and active microfluidic approaches for label-free,high-resolution separation of EVs from biological matrix based on their physical properties.As an example of passive method,viscoelastic microfluidics exploits the size-dependent elastic lift force imposed on EVs in a viscoelastic medium,allowing for the high-resolution isolation of EVs from biofluids.The active methods leverage the use of externally applied physical fields(e.g.,electric and acoustic fields)to achieve rapid separation of submicron-sized EVs.We then summarize different signal amplification and detection strategies implemented with microfluidic platforms for sensitive and specific characterization of EVs in clinical samples.The combination of microfluidics with thermophoresis-assisted fluorescence detection,surface plasmon resonance(SPR),surface-enhanced Raman scattering(SERS),and magnetic detection have been employed to profile EV surface proteins,miRNAs,mRNAs,etc.These EV-associated biomarkers reveal great potential for the diagnosis,monitoring,and prognosis of cancer.We also survey the progress in microfluidic engineering of EVs that utilizes the intensive physical(acoustic and electric fields)or mechanical force fields to load active cargo into EVs in a reproducible,continuous manner.The engineered EVs have been developed as advanced delivery systems with improved immune evasion,targeting capability,and therapeutic effectiveness.Finally,we conclude this Account by outlining the challenges,opportunities,and future directions in the microfluidic investigation of EVs in the clinic and in vivo.