Characterization of cuttlebone for a biomimetic design of cellular structures

Cuttlebone is a natural material possessing the multifunctional properties of high porosity, high flexural stiffness and compressive strength, making it a fine example of design optimization of cellular structures created by nature. Examination of cuttlebone using scanning electron micros- copy （SEM） reveals an approximately periodic microstruc- ture, appropriate for computational characterization using direct homogenization techniques. In this paper, volume fractions and stiffness tensors were determined based on two different unit cell models that were extracted from two different cuttlefish samples. These characterized results were then used as the target values in an inverse homogenization procedure aiming to re-generate microstructures with the same properties as cuttlebone. Unit cells with similar topologies to the original cuttlebone unit cells were achieved, attaining the same volume fraction （i.e. bulk density） and the same （or very close） stiffness tensor. In addition, a range of alternate unit cell topologies were achieved also attaining the target properties, revealing the non-unique nature of this inverse homogenization problem.

One-step growth of the interconnected carbon nanotubes/graphene hybrids from cuttlebone-derived bi-functional catalyst for lithium-ion batteries

Carbon nanotubes/graphene hybrid materials with excellent physicochemical properties can be widely ap-plied in the fields of energy storage,electrocatalysis,sensing,etc.Reducing the self-stacking and achiev-ing covalent interaction between carbon nanotubes and graphene are important to ensure a stable hi-erarchical architecture and effective mass transfer.Herein,we propose a one-step strategy to synthesize 3D interconnected carbon nanotubes/graphene hybrids on the easy-to-remove biomass-derived substrate.The calcined natural cuttlebone as bi-functional catalyst precursor can simultaneously grow carbon nan-otubes and graphene by one-step chemical vapor deposition without the addition of extra metal catalysts,while the interconnected structure can act as the porous template for graphene growth.The simultane-ous growth process can obtain covalent bonding between carbon nanotubes and graphene,while the crystalline quality and interlayer space can be adjusted by different carbon sources and growth parame-ters(e.g.,temperature).The one-step grown carbon nanotubes/graphene hybrids with seamless interfaces and hierarchical interconnected 3D structure can effectively enhance the electron transfer as well as the electrolyte infiltration efficiency.When utilized as lithium-ion batteries(LIBs)anode,a high specific ca-pacity(544 mAh g^(-1) at 0.1 A g^(-1)),good rate capability(200 mAh g^(-1) at 6.4 A g^(-1) with an ultrashort charge time of 113 s),and excellent cyclic stability can be achieved.This simple and one-step carbon nanotubes/graphene hybrids fabrication strategy can be easily scale-up and applied in various fields.

Cuttlebone： Characterisation, Application and Development of Biomimetic Materials

Cuttlebone signifies a special class of ultra-lightweight cellular natural material possessing unique chemical, mechanical and structural properties, which have drawn considerable attention in the literature. The aim of this paper is to better understand the mechanical and biological roles of cuttlebone. First, the existing literature concerning the characterisation and potential applications inspired by this remarkable biomaterial is critiqued. Second, the finite element-based homogenisation method is used to verify that morphological variations within individual cuttlebone samples have minimal impact on the effective me- chanical properties. This finding agrees with existing literature, which suggests that cuttlebone strength is dictated by the cut- tlefish habitation depth. Subsequently, this homogenisation approach is further developed to characterise the effective me- chanical bulk modulus and biofluidic permeability that cuttlebone provides, thereby quanti lying its mechanical and transporting functionalities to inspire bionic design of structures and materials for more extensive applications. Finally, a brief rationale for the need to design a biomimetic material inspired by the cuttlebone microstructure is provided, based on the preceding inves- tigation.

Conversion of natural marine skeletons as scaffolds for bone tissue engineering

Marine CaCO3 skeletons have tailored architectures created by nature, which give them structural support and other functions. For example, seashells have dense lamellar structures, while coral, cuttlebone and sea urchin spines have interconnected porous structures. In our experiments, seashells, coral and cuttlebone were hydrothermaily converted to hydroxyapatite （HAP）, and sea urchin spines were converted to Mg-substituted tricalcium phosphate, while maintaining their original structures. Partially converted shell samples have mechanical strength, which is close to that of compact human bone. After implantation of converted shell and spine samples in rat femoral defects for 6 weeks, there was newly formed bone growth up to and around the implants. Some new bone was found to migrate through the pores of converted spine samples and grow inward. These results show good bioactivity and osteoconductivity of the implants, indicating the converted shell and spine samples can be used as bone defect fillers. The interconnected porous HAP scaffolds from converted coral or cuttlebone that have pore size larger than 100μm likely support infiltration of bone cells and vessels, and finally encourage new bone ingrowth.