Cationized Melamine-formaldehyde Resin for Improving the Wet Strength of Paper

In this work, melamine-formaldehyde resin was cationized by adding modifiers so that the fibers closely bonded to improve their usability and the wet strength of paper was greatly improved. Triethanolamine and dimethylamine were added to modify the melamine-formaldehyde resin,respectively.The mechanism of the cationized resin was explored and the possible chemical reactions were deduced. It was concluded that,with the use of triethanolamine,the most optimum product was obtained by hydroxymethylation for 30 min with a temperature of 85℃ and p H of 9. 0 where n( melamine) ∶ n( formaldehyde) ∶ n( methanol) ∶ n( triethanolamine) was 100 ∶ 330 ∶ 450 ∶ 15. With the combined use of dimethylamine and methanol,the optimal product was acquired by condensation for 30 min at a temperature of 50℃ and p H of 2. 0 at melamine, formaldehyde, methanol, and dimethylamine molar ratio of100∶ 330∶ 350∶ 20. With the only use of dimethylamine,the optimal product was obtained by condensation at melamine,formaldehyde,dimethylamine molar ratio of 100∶ 330∶ 10. The wet tensile strength of fruit-bagging paper was improved by adding cationized melamine-formaldehyde resin. The zeta potential,charge density,and conductivity of the melamine-formaldehyde resin were also studied.

High-value Applications of Nanocellulose

Nanocelluloses, obtained from the biopolymer cellulose, are a class of renewable functional nanomaterials with excellent properties and a broad range of applications. This review mainly illustrates practical and advanced applications of nanocellulose-based materials in the following categories.(1) Fire-resistant materials: in the section on these types of materials, the fireprotection property of nanocellulose/clay hybrid composites(clay nanopaper) is illustrated; oriented montmorillonite(MTM) provides barrier properties and low thermal conductivity whereas cellulose nanofibers(CNFs) impart favorable charring.(2) Thermal insulation materials: the best way to obtain materials with good heat insulation performance is to decrease the thermal conductivity of such materials.(3) Template materials: nanocellulose can direct the deposition and patterning of materials to form nanoparticles, nanowires, or nanotubes with improved properties.

One-step Fabrication of Cellulose/Graphene Conductive Paper

In this study,a straightforward,one-step wet-end formation process was employed to prepare cellulose/graphene conductive paper for antistatic packing materials.Cationic polyacrylamide was introduced into the cellulose/graphene slurry to improve the graphene loading on the surfaces of the cellulose fibers.The effect of the super calender process on the properties of the cellulose/graphene conductive paper was investigated.When 55 wt% graphene was added,the volume resistivity of the cellulose/graphene conductive paper was 94.70 W·cm,decreasing to 35.46 W·cm after the super calender process.The cellulose/graphene conductive paper possessed excellent anti-static ability and could be used as an anti-static material.

Industrialization Progress of Nanocellulose in China

Nanocellulose,a kind of cellulose with nanometer sizes,has drawn great interest in the pulp and paper industry due to its unique structure and excellent performance.It can be divided into five categories:nanocrystalline cellulose(NCC),nanofibrillated cellulose(NFC),bacterial cellulose(BC),electrospun cellulose nanofibers(ESC),and precipitation regenerated cellulose nanofibers(PRC).In this paper,we reviewed the industrialization progress of nanocellulose in China.Furthermore,we proposed that efficient and environmentally friendly preparation methods and high value utilization would be the focus of nanocellulose development.

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.

The construction of drug-resistant cancer cell lines by CRISPR/Cas9 system for drug screening

Cancer therapy is often hampered by the rapid emergence of drug resistance. Drug-resistant cellular models are essential for understanding the drug resistance and developing new therapeutics. The low efficiency and long time required in creating these models are major obstacles hindering drug resistance research and drug screening. Herein, we report an approach that can accelerate(shortening the time from years to 3 weeks) the establishment of cancer cell line-based, inheritable drug resistance models by specific knockout of MED12 gene using CRISPR/Cas9 system. The resultant MED12^(KO) A375(melanoma)cell line was resistant to inhibitors of B-Raf proto-oncogene, serine/threonine kinase(BRAF), whereas the resultant MED12^(KO) PC9(non-small cell lung cancer) cell line was resistant to inhibitors of epidermal growth factor receptor(EGFR). Evaluation of anti-cancer drugs and their combinations shows that certain combinations of BRAF inhibitors and TGF-β receptor(TGF-βR) inhibitors are active in suppressing the growth of MED12^(KO) A375 cells, and a few combinations of EGFR inhibitors and TGF-βR inhibitors were active in suppressing the growth of MED12^(KO) PC9 cells. The drug-resistant models will be useful in screening novel drugs and drug combinations for multi-drug-resistant cancer therapy.

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 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.

Exosome-Coated Zeolitic Imidazolate Framework Nanoparticles for Intracellular Detection of ATP

The intracellular delivery of metal-organic frameworks(MOFs)encapsulated with functional biomolecules represents a promising av-enue in the field of biomedicine and biosensing.To improve the cellular uptake efficiency of MOFs,here we report the fabrication of cancer cell-derived exosome membra ne(EM)-coated zeolitic imidazolate framework-8(EM-ZIF-8)nan oparticles by using a microfluidic son ication device.

Nanoliposome-encapsulated caged-GABA for modulating neural electrophysiological activity with simultaneous detection by microelectrode arrays

Effective and precise neural modulation with real-time detection in the brain is of great importance and represents a significant challenge.Nanoliposome-encapsulated light-sensitive compounds have excellent characteristics such as high temporal and spatial resolution,delayed drug clearance,and restricted drug biodistribution for neural modulation.In this study,we developed a nanoliposome-based delivery system for ruthenium-based caged GABA compounds(Nanolipo-Ru)to modulate neural activity and allow for real-time monitoring using the microelectrode arrays(MEAs).The Nanolipo-Ru nanoparticles had an average size of 134.10±4.30 nm and exhibited excellent stability for seven weeks.For the in vivo experiment in the rat,release of GABA by Nanolipo-Ru under blue light illumination resulted in an average firing rate reduction in interneurons and pyramidal neurons in the same brain region of 79.4%and 81.6%,respectively.Simultaneously,the average power of local field potentials in the 0–15 Hz range degraded from 4.34 to 0.85 mW.In addition,the Nanolipo-Ru nanoparticles have the potential to provide more flexible timing of modulation than unencapsulated RuBi-GABA in the experiments.These results indicated that Nanolipo-Ru could be an effective platform for regulating neuronal electrophysiology.Furthermore,nanoliposomes with appropriate modifications would render promising utilities for targeting of specific types of neurons in the future.