Review on 3D Prototyping of Damage Tolerant Interdigitating Brick Arrays of Nacre

3D-Printed Biomimetic Hierarchical Nacre Architecture: Fracture Behavior and Analysis

Nacreous architecture has a good combination of toughness and modulus, which can be mimicked at the micron to submicron level using 3D printing to resolve the demand in numerous applications such as automobile, aerospace, and protection equipment. The present study examines the fabrication of two nacre structures, a nacre columnar (NC) and a nacre sheet (NS), and a pristine structure via fused deposition modeling (FDM) and explores their mechanically superior stacking structure, mechanism of failure, crack propagation, and energy dissipation. The examination reveals that the nacre structure has significant mechanical properties compared to a neat sample. Additionally, NS has 112.098 J/m impact resistance (9.37% improvement), 803.415 MPa elastic modulus (11.23% improvement), and 1563 MPa flexural modulus (10.85% improvement), which are all higher than those of the NC arrangement.

Three-dimensional printing of molluscan shell inspired architectures via fused deposition modeling

Nature always astonishes us with its marvelous creations which act as a model for acquiring a solution to complex human problems, this practice of designing and manufacturing the product replicating processes that occur in nature is referred to as biomimicking. Molluscan shell is nature's one such offering that delivers remarkable mechanical properties by virtue of its hierarchical multi-layered structure. In this work, a peculiar avenue for facile biomimicking multitudinous molluscan shell architectures such as complex cross lamellar, cross lamellar, foliated, prismatic, columnar nacre, and sheet nacre structure are manufactured by 3D prototyping of biodegradable, biocompatible polylactic acid (PLA). Here, the reliance of mechanical attributes of PLA on various architectures is studied and demonstrated that the nacre, owing to its complex structure, leads to high energy dissipation (12.5094 J/m) imparting high toughness.

Review of manufacturing three-dimensional-printed membranes for water treatment

With the exacerbation of industrialization, water treatment has become a necessary step for the eradication of dyes, heavy metals, oils, pharmaceuticals, and illicit drugs. These pollutants pose an impending threat to the health of humans by causing chronic or acute poisoning. Albeit they are noxious, the presence of some metals in lower concentrations is indispensable for human health. 3D printing (additive manufacturing) (3DP) can contrive nearly any complicated geometric form in a wide array of objects among various scales by a layer-wise method of manufacturing, which is more indubitably designed than any other conventional method. 3DP could remodel the existing patterns of membrane housing and possibly trim down the power demand and chemical use in saltwater desalinating and wastewater purification plants. Membranes that are 3D printed with correctly arranged apertures and shapes enhance material transport and flow athwart the surface of the membrane and at once lessen membrane soiling. This kind of technology forges membranes of polymers, biopolymers, alloys, metals, and ceramics via computer-aided design (CAD). A polylactic acid porous super-hydrophobic membrane with pore size in the range 40-600 μm showed 99.4% oil-water separating power and 60 kL h^-1 m^-2 flux when the pore size was tuned to 250 μm via CAD-aided 3D printing technology. This review focuses on the ability of 3D-printed membranes for the efficient removal of toxic pollutants from wastewater. Graphical abstract 3D-printed membranes for water treatment.

Bioinspired Compliance Grading Motif of Mortar in Nacreous Materials

The impressive toughness and strength of natural nacre, attributed to its multi-scale and -material hierarchical architecture, has inspired biomimicry and bioinspired materials development, and here we show that material compliance gradients are a motif that can help explain their advantaged mechanical performance. We present experiments enabled via additive manufacturing that allow direct evaluation of a compliance grading motif of the mortar between the relatively stiff bricks of the nacreous material. Spatial grading of the mortar compliance redistributes stresses away from critical regions (at, and around, brick corners), resulting in overall increases of ∼60% in strength, ∼ 70% in toughness, and ∼30% in strain-to-break, while maintaining macroscopic stiffness. Mechanistically, failure initiation threshold is delayed due to enhanced strain-tolerance and strain-localization as revealed in prefailure experimental strain maps, and in agreement with numerical analyses. We further demonstrate that this modulus grading motif, beyond the stiffness mismatch between the brick and mortar periodic architecture, is a significant contributor to the performance of the much-studied nacreous systems and is suggested as a natural but overlooked mechanism in such systems.

Review of alginate-based hydrogel bioprinting for application in tissue engineering

The dawn of 3D printing in medicine has given the field the hope of vitality in many patients fighting a multitude of diseases. Also entitled bioprinting, this appertains to its sequential printing of precursor ink, embodying cells and polymer/composite in a predetermined trajectory. The precursor ink, in addition to cells, is predominantly constituted of hydrogels due to its biodegradability and ability to mimic the body's anatomy and mechanical features, e.g. bones, etc. This review paper is devoted to explicating the bioprinting (3D/4D) of alginate hydrogels, which are extracts from brown algae, through extrusion additive manufacturing. Alginates are salt derivatives of alginic acid and constitute long chains of polysaccharides, which provides pliability and gelling adeptness to their structure. Alginate hydrogel (employed for extrusion) can be pristine or composite relying on the requisite properties (target application controlled or in vivo environment), e.g. alginate-natural (gelatin/agarose/collagen/hyaluronic acid/etc) and alginate-synthetic (polyethylene glycol (PEG)/pluronic F-127/etc). Extrusion additive manufacturing of alginate is preponderate among others with its uncomplicated processing, material efficiency (cut down on wastage), and outspread adaptability for viscosities (0.03-6 * 10⁴ Pa.s), but the procedure is limited by resolution (200 μm) in addition to accuracy. However, 3D-fabricated biostructures display rigidness (unvarying with conditions) i.e. lacks a smart response, which is reassured by accounting time feature as a noteworthy accessory to printing, interpreted as 4D bioprinting. This review propounds the specific processing itinerary for alginate (meanwhile traversing across its composites/blends with natural and synthetic consideration) in extrusion along with its pre-/during/post-processing parameters intrinsic to the process. Furthermore, propensity is also presented in its (alginate extrusion processing) application for tissue engineering, i.e. bones, cartilage (joints), brain (neural), ear, heart (cardiac), eyes (corneal), etc, due to a worldwide quandary over accessibility to natural organs for diverse types of diseases. Additionally, the review contemplates recently invented advance printing, i.e. 4D printing for biotic species, with its challenges and future opportunities.

Biomineralization Forming Process and Bio-inspired Nanomaterials for Biomedical Application: A Review

Biomineralization is a process in which organic matter and inorganic matter combine with each other under the regulation of living organisms. Because of the biomineralization-induced super survivability and retentivity, biomineralization has attracted special attention from biologists, archaeologists, chemists, and materials scientists for its tracer and transformation effect in rock evolution study and nanomaterials synthesis. However, controlling the biomineralization process in vitro as precisely as intricate biology systems still remains a challenge. In this review, the regulating roles of temperature, pH, and organics in biominerals forming process were reviewed. The artificially introducing and utilization of biomineralization, the bio-inspired synthesis of nanomaterials, in biomedical fields was further discussed, mainly in five potential fields: drug and cell-therapy engineering, cancer/tumor target engineering, bone tissue engineering, and other advanced biomedical engineering. This review might help other interdisciplinary researchers to bionic-manufacture biominerals in molecular-level for developing more applications of biomineralization.