Heart-on-chips screening based on photonic crystals

Recently,organ-on-chips have become a fast-growing research field with the widespread development of microfluidic chips and synthetic materials in tissue engineering.Due to the existing cardiotoxicity of many cardiovascular drugs,heart-onchips which are promising to replace traditional animal models have been extensively researched and developed to mimic human organ functions in vitro.The heart-on-chips mainly focus on cardiac mechanics,which is regarded as the central indicator of in vitro heart models and drug testing.Traditional methods for the detection of myocardial mechanics have been demonstrated complex and inefficient in heart-on-chips.Therefore,photonic crystal materials with unique optical properties have attracted interests and have been introduced into the heart-on-chips,developing a visualized self-reporting system for cardiomyocytes activity monitoring.In this review,photonic crystal-based heart-on-chips for biosensing are introduced,as well as the fabricationmethods and design criteria of them.The characterizations of the photonic crystal materials are classified into optical properties and structural properties,and their applications in cell culture and biosensing are further discussed.Then,several representative examples and developments of the integration of photonic crystal materials into microfluidic chips are described in detail.Finally,potentials and limitations are put forward to promote the development of the photonic crystal-based intelligent heart-on-chips.

Bio-inspired angle-independent structural color films with anisotropic I colloidal crystal array domains

Structural color materials with the property of angle-independence have attracted increasing interest in recent years because of their applications in various research fields.In this paper,inspired by the anisotropic lattice microstructure of the Parides sesostris butterfly,we i present a novel angle-independent structural material by simply doping spinous pollen particles into the colloidal crystal arrays to interfere their self-assembling process.The resultant composited materials have anisotropic dose-packed colloidal crystal domains around the spikes of the pollens.These differently oriented domains could reflect the light to a wide range of viewing angles,and thus imparted the composite materials with the same wide angle of structural colors.Attractively,the materials were endowed with light-controlled reversible structural color changing behavior by incorporating photothermal responsive graphene-tagged hydrogels.These features of the bioinspired angle-independent structural color materials showed their potential values in constructing intelligent sensors,anti-counterfeiting barcode labels,and so on.

Elastin-like polypeptide modified silk fibroin porous scaffold promotes osteochondral repair

Silk fibroin(SF)is considered biocompatible and biodegradable for osteochondral repair.However,it lacks a bioactive domain for cell adhesion,proliferation and differentiation,limiting its therapeutic efficacy.To revamp SF as a biomimicking and bioactive microenvironment to regulate cell behaviours,we engineered an elastin-like polypeptide(ELP,Val-Pro-Gly-Xaa-Gly)to modify SF fibers via simple and green dehydrothermal(DHT)treatment.Our results demonstrated that the ELP successfully bound to SF,and the scaffold was reinforced by the fusion of the silk fiber intersections with ELP(S-ELP-DHT)via the DHT treatment.Both bone mesenchymal stem cells(BMSCs)and chondrocytes exhibited improved spreading and proliferation on the S-ELP-DHT scaffolds.The ex vivo and in vivo experiments further demonstrated enhanced mature bone and cartilage tissue formation using the S-ELP-DHT scaffolds compared to the naked SF scaffolds.These results indicated that a recombinant ELPmodified silk scaffold can mimic three-dimensional(3D)cell microenvironment,and improve bone and cartilage regeneration.We envision that our scaffolds have huge clinical potential for osteochondral repair.

Hierarchical Hydrogels with Ordered Micro-Nano Structures for Cancer-on-a-Chip Construction

In the drug therapy of tumor,efficient and stable drug screening platforms are required since the drug efficacy varies individually.Here,inspired by the microstructures of hepatic lobules,in which hepatocytes obtain nutrients from both capillary vessel and the central vein,we present a novel hierarchical hydrogel system with ordered micro-nano structure for liver cancer-on-a-chip construction and drug screening.The hierarchical hydrogel system was fabricated by using pregel to fill and replicate selfassembled colloidal crystal arrays and microcolumn array template.Due to the synergistic effect of its interconnected micro-nano structures,the resultant system could not only precisely control the size of cell spheroids but also realize adequate nutrient supply of cell spheroids.We have demonstrated that by integrating the hierarchical hydrogel system into a multichannel concentration gradients microfluidic chip,a functional liver cancer-on-a-chip could be constructed for high-throughput drug screening with good repeatability and high accuracy.These results indicated that the hierarchical hydrogel system and its derived liver cancer-on-a-chip are ideal platforms for drug screening and have great application potential in the field of personalized medicine.

Sex differences in anogenital distances and digit ratios in wild David＇s rock squirrels Sciurotamias davidianus

The prenatal hormonal environment plays an important role in organizing sex differences in the morphology, physiology and behavior of humans as well as other vertebrates. Currently, all related research on rodents has been focused on Myomorpha. This study presents data on sex differences in the anogenital distance （AGD） and the ratio of the second to the fourth digit length （2D：4D） from 44 wild David＇s rock squirrels Sciurotamias davidianus captured from the Qinling Mountains, China. This was the first study of a species from Sciuromorpha. The AGD as well as body mass are sexually dimorphic. There are no sex differences or lateral asymmetry in 2D：4D. Significant correlation was not found between AGD and 2D：4D for any paw. The findings indicate that 2D：4D may not be fixed or influenced by the prenatal steroidal environment in David＇s rock squirrels [Current Zoology 60 （2）： 180-185, 2014].

Sex-specific participation in inter-group conflicts within a multilevel society:the first evidence at the individual level

Inter-group conflicts are common among many group-living animals and involve potentially complex motivations and interactions.Mammals living in multilevel societies offer a good opportunity to study inter-group conflicts.This study is the first to explore the function of sex-specific participation during inter-group conflicts within a multilevel society at the individual level.The Sichuan snub-nosed monkey(Rhinopithecus roxellana)is an endangered seasonal breeding species living in a multilevel society.From Sep 2007 to May 2008 we recorded 290 inter-group conflicts of a free-ranging provisioned band of R.roxellana in the Qinling Mountains of China to investigate the function of individual aggression during inter-group encounters.Our findings show that adult males were the main participants in inter-group conflicts,while females took part in them only occasionally.The male participation rate during the mating season,when adult females were estrous,was significantly higher than that during the non-mating season.Furthermore,males directed their aggression to other males,and directed more intense aggression towards bachelor males than towards other resident males.For both sexes,the participation rate as initiators was higher in the winter than that in the spring;and there was a significant positive correlation between group size and the participation rate as initiators.Our results suggest that inter-group aggression in Sichuan snub-nosed monkeys is linked to both mate defense and resource defense.

Hierarchical Hydrogels with Ordered Micro-Nano Structures for Cancer-on-a-Chip Construction

In the drug therapy of tumor,efficient and stable drug screening platforms are required since the drug efficacy varies individually.Here,inspired by the microstructures of hepatic lobules,in which hepatocytes obtain nutrients from both capillary vessel and the central vein,we present a novel hierarchical hydrogel system with ordered micro-nano structure for liver cancer-on-a-chip construction and drug screening.The hierarchical hydrogel system was fabricated by using pregel to fill and replicate self-assembled colloidal crystal arrays and microcolumn array template.Due to the synergistic effect of its interconnected micro-nano structures,the resultant system could not only precisely control the size of cell spheroids but also realize adequate nutrient supply of cell spheroids.We have demonstrated that by integrating the hierarchical hydrogel system into a multichannel concentration gradients microfluidic chip,a functional liver cancer-on-a-chip could be constructed for high-throughput drug screening with good repeatability and high accuracy.These results indicated that the hierarchical hydrogel system and its derived liver cancer-on-a-chip are ideal platforms for drug screening and have great application potential in the field of personalized medicine.