On mechanical properties of nanocomposite hydrogels:Searching for superior properties

Nanocomposite hydrogels are the combination of known components that are a hydrogel and nanometre-sized fillers,typically leading to improved mechanical properties or new functionalities.With simplicity of design and ease of synthesis,recent advances have highlighted that this family of hydrogels holds the significant promise of application in diverse biomedical and engineering fields.The elaborate design and investigation as well as suitable application of nanocomposite hydrogels require the synergy of mechanics,materials science,engineering,and biology.Despite similarities in design and fabrication,the data of mechanical properties for nanocomposite hydrogels scatter in a large space.It is worthwhile comparing various nanocomposite hydrogels for similarities and differences in mechanical properties to aid in designing novel hydrogels with extreme properties,and guide practical applications.This review aims to fill,in the literature,the missing gap of addressing mechanical measurement methods and comparison of mechanical properties in this ever-evolving broad area of research.Finally,the challenges and future research opportunities are highlighted.

Thin-film flow technology in controlling the organization of materials and their properties Special Collection:Distinguished Australian Researchers

Centrifugal and shear forces are produced when solids or liquids rotate.Rotary systems and devices that use these forces,such as dynamic thin-film flow technology,are evolving continuously,improve material structure-property relationships at the nanoscale,representing a rapidly thriving and expanding field of research high with green chemistry metrics,consolidated at the inception of science.The vortex fluidic device(VFD)provides many advantages over conventional batch processing,with fluidic waves causing high shear and producing large surface areas for micro-mixing as well as rapid mass and heat transfer,enabling reactions beyond diffusion control.Combining these abilities allows for a green and innovative approach to altering materials for various research and industry applications by controlling small-scale flows and regulating molecular and macromolecular chemical reactivity,self-organization phenomena,and the synthesis of novel materials.This review highlights the aptitude of the VFD as clean technology,with an increase in efficiency for a diversity of top-down,bottom-up,and novel material transformations which benefit from effective vortex-based processing to control material structure-property relationships.

AIEgens in cell-based multiplex fluorescence imaging

Fluorescence imaging is an important branch of bioimaging.It is non-invasive and provides superior spatial and temporal resolution during the real-time monitoring of biological samples of interest.Although the spatial resolution limit of optical microscopes is about 200 nm,due to the diffraction limit,with the application of super-resolution fluorescence microscopy technologies this limit has been pushed below 30 nm.This makes it feasible to visualize biological structures in subcellular levels and to monitor subcellular biological processes in real time.However,due to the complexity of the biological structure and components within cells,simultaneous staining and monitoring multiple intracellular components with different coloured fluorophores is often needed during multiplex imaging,to better understand biological processes.Aggregation-induced emission luminogens(AIEgen)and AIEgen based nanoparticles(NPs)have presented many advantages in fluorescence imaging,with strong potential for biological science and nano-medicine.Herein this review,we focus on the advantages of AIEgen and AIEgen NP in cell-based fluorescence imaging,and the latest advances of AIEgens in cell-based multiplex imaging are summarized and discussed.The future perspectives are proposed.

Preparation of Silver Nanowires via a Rapid,Scalable and Green Pathway

Rapid synthesis of silver nanowires(Ag NWs) with high quality and a broad processing window is challenging because of the low selectivity of the formation of multiply twinned particles at the nucleation stage for subsequent Ag NWs growth.Herein we report a systematic study of the water-involved heterogeneous nucleation of Ag NWs with high rate(less than 20 min) in a simple and scalable preparation method.Using glycerol as a reducing agent and a solvent with a high boiling point,the reaction is rapidly heated to 210 ℃ in air to synthesize Ag NWs with a very high yield in gram level.It is noted that the addition of a small dose of water plays a key role for obtaining highly pure Ag NWs in high yield,and the optimal water/glycerol ratio is0.25%.After investigating a series of forming factors including reaction temperature and dose of catalysts,the formation kinetics and mechanism of the Ag NWs are proposed.Compared to other preparation methods,our strategy is simple and reproducible.These Ag NWs show a strong Raman enhancement effect for organic molecules on their surface.

Multiplexed imaging detection of live cell intracellular changes in early apoptosis with aggregation-induced emission fluorogens

Apoptosis is an important process for maintaining tissue homeostasis and eliminating abnormal cells in multicellular organisms.Abnormality in apoptosis often leads to severe diseases such as cancers. Better understanding of its mechanisms and processes is therefore important. Accompanying molecular biology events of apoptosis is a series of cellular morphology changes: nucleus condensation, cell shrinkage and rounding, cell surface blebbing, dynamic blebbing, apoptotic membrane protrusions and nucleus fragmentations and finally, the formation and release of apoptotic bodies. It is difficult to detect cellular changes in the early phase of apoptosis due to the subtle changes at this phase. In the current study, we induced apoptosis in He La cells with H2 O2 and used nuclear dye Hoechst 33258, mitochondria, lysosome and cytoplasmic protein specific aggregation-induced emission fluorogens(AIEgens), TPE-Ph-In, 2 M-DABS and BSPOTPE to successfully perform live cell multiplexed imaging to investigate early apoptosis cellular events. We showed the gradual dissipation of mitochondria membrane potential until it is nondetectable by TPE-Ph-In. Increased mitophagy detected by TPE-Ph-In and 2 M-DABS, condensed nucleus detected by Hoechst33258, increased permeability and/or reduced integrity of nuclear membrane, and increased intracellular vesicles detected by2 M-DABS are some of the early events of apoptosis.

Synthetic fluorescent probes to apprehend calcium signalling in lipid droplet accumulation in microalgae——an updated review

Lipid bodies are dynamic organelles of photosynthetic microalgae that can be used as the third generation resources for biofuel production.Biosynthesis of lipids can be influenced by different signalling processes.Visualisation of these processes can provide useful information about the fate and associated roles of lipid molecules in different biological systems.In photosynthetic organisms,however,studies of calcium ediated lipid biosynthesis is bottlenecked due to the limitation of proper and efficient technologies,which also include visualisation techniques.Currently,most studies to visualise lipid droplets in vivo have used traditional dyes,and proper visualisation of lipid drops is hindered by dye-specific limitations.This hurdle could be overcome by using recently developed aggregation-induced emission biooprobes.This review reveals current knowledge gaps in the studies of lipid drops and calcium ions in microalgae,as calcium signaling is important secondary messenger to detect a wide variety of environmental stimuli in plant and animal cells.To obtain insight into the mechanisms of these processes,the merits and demerits of currently available visualisation techniques for lipid drops and calcium are also detailed.Finally,opportunities and possibilities are proposed to recommend further improvement of techniques for detecting the role of calcium during lipid formation in microalgae for biofuel production.

Strategies in boosting photosensitization for biomedical applications

Photodynamic therapy(PDT)has emerged as an effective treatment method for its few adverse effects,little invasiveness,short treatment time and low cost[1,2].The rapid development of PDT has dramatically boosted its multifaceted applications in cancer treatment,antibacterial and immunotherapy,etc.[3-5].

AIEgen-enhanced protein imaging:Probe design and sensing mechanisms

Proteins are the building blocks of life,regarded as one of the most complex and crucial biomacromolecules in biological systems,and playing a significant role in executing genes and transferring genetic information.According to recent research,due to the structural intricacy of proteins and their sensitivity to physical and chemical degradation processes,they could be utilized as biomarkers or therapeutic agents in the diagnosis,treatment,or even prevention of different diseases.Therefore,modern pathways have been developed for understanding the function of proteins,resulting in intriguing approaches in the field of protein-related diseases.The diagnostic strategies to deal with such diseases,including protein analysis,protein quantification,and protein imaging,were argued in depth.Meanwhile,the aggregationinduced emission(AIE)concept and its potential applications for real-time imaging make AIE luminogens(AIEgen)attractive for protein imaging.In general,AIEgens refer to those luminogenic chemicals that are nonluminescent in solution,but luminescent in either the aggregated or solid states.This review is focused on the emergence of AIE materials in protein tracking,detecting,and imaging for medical applications.

Revisiting an ancient inorganic aggregation-induced emission system:An enlightenment to clusteroluminescence

Organic and inorganic clusteroluminescence have attracted great attention while the underlying mechanisms is still not well understood.Here,we employed a series of ancient inorganic complexes platinocyanides with aggregation-induced emission property to elucidate the mechanism of clusteroluminescence including how does the chromophore form and how does the solid structures influence the luminescence behaviors.The results indicate that the isolated platinocyanide cannot work as a chromophore to emit visible light,while their clusterization at aggregate state can trigger the d-orbitals coupling of the platinum atoms to facilitate the electron exchange and delocalization to form a new chromophore to emit visible light.Furthermore,the counter ions and H2O ligands help to rigidify the three-dimensional network structure of the platinocyanides to suppress the excited state nonradiative decay,resulting in the high quantum yield of up to 96%.This work fundamentally helps understanding both the organic and inorganic clusteroluminescence phenomenon.

Organoclay/thermotropic liquid crystalline polymer nanocomposites.Part VI:Effects of intercalated organoclay on nanocomposite morphology,thermal and rheological properties

A study of a typical intercalated structure of a thermotropic liquid crystalline polymer(TLCP)with organoclay was performed to elucidate the influence of intercalated organoclay on the TLCP molecules,especially on their liquid crystallinity,thermal and rheological properties.The intercalated structures were confirmed in TLCP and organoclay formed molecular interactions with TLCP molecules in the system.Such intercalated structures caused the glass transition temperature of the nanocomposite to become invisible in thermal measurement and also caused loss of liquid crystallinity.The TLCP molecules inside the organoclay galleries showed higher thermal stability and transition temperatures,but the orderly structure of the TLCP molecules outside the galleries was destroyed by the organoclay,causing the TLCP to display lower thermal stability and transition temperatures than pristine TLCP.At 185℃,where TLCP is in the nematic phase,the nanocomposite had three orders of magnitude higher viscosity in the linear viscoelastic region than that of TLCP,with chain mobility and relaxation time slowed due to the intercalated effects in the nanocomposite.Steady shear altered the domain sizes and oriented the highly anisotropic organoclay layers or tactoids along the shear direction.

Interactions between stearic acid and calcite surfaces:Experimental and computer simulation studies

Calcite surface was modified with stearic acids,and the interaction between them was investigated both experimentally and theoretically.Stearic-acid-modified calcite powders were investigated with Fourier transform infrared spectroscopy,X-ray diffraction,zeta potential analyser and contact angle measurement.Then,the density functional theory calculations were performed to explore the interaction at the atomic scale.The experi-mental results and simulation indicated that stearic acids interact with calcite surface via chelation between the double-bond O atom of-COOH and the Ca atom on calcite surface.The terminal methyl group of the stearic acids decreases the hydrophilicity of the calcite surface,and the interaction between different crystal faces of calcite is different.