Explore the vast range of titles available.

Two-dimensional materials are becoming a new sensation in the chemical, electrical, energy storage, and biomedical industries. Since the invention of graphene, scientists worldwide have been attempting to explore novel 2D materials. High surface-to-volume ratio, lightweight, anisotropy, and multi-functionality are some special features of these 2D materials. Such characteristics can be merged with the fabrication flexibility of 3D printing to develop complex structures including shape, size, and functionality. These complex 3D-printed 2D materials can be used in novel biomedical applications, including the advancement of targeted drug delivery, cancer therapy, tissue engineering, and biosensors. This review article focuses on the recent development of 3D/4D printed complex structures from 2D nanomaterials in biomedical applications. We have assessed the concept of hybridization of existing 2D nanomaterials and discussed the significance of computational modeling in 2D nanomaterials. Current trends, challenges, and prospects of 3D/4D-printed 2D nanomaterials in the biomedical field are also delineated. Graphic abstract

Since its isolation, single atomically thin layer of graphite, called graphene by Geim and co-workers, has received a lot of attention from the research community as well as industry. Interesting and ground-breaking research has been published on graphene showing excellent properties and a wide range of applications. Taking inspiration from graphene, the materials community started atomically exploring materials, which resulted in the development of two-dimensional (2D) materials family consisting of elemental metals, metal carbides, dichalcogenide, oxide, nitride and others. Engineering such atomically thin materials is different from conventional materials. In the current summary, the different methods/processes of engineering materials at atomic scale have been summarized. In the first section, the exfoliation of 2D materials from their bulk phase and tuning their composition, thickness and other physical, chemical and optical properties are discussed. Taking inspiration from atomically engineered topological complex architectures have been 3D printed. Such architecture shows superior structural and functional properties. In the last section of the paper, nature-inspired processes have been utilized to build advanced/unique materials using energy-efficient method. These bio-inspired materials have been utilized in environment, energy and health care.

The present work aimed to investigate the deformation behavior of complex ant mound architectures under compression. We have used the cement casting method to extract four different ant nest morphologies. These casted cement structures were digitalized using a 3D micro-computer tomography scan. The digitized structures were simulated under different loading conditions using finite-element methods (FEMs). In order to supplement the numerical understanding, the digital architectures were 3D printed and experimentally tested under uniaxial loading conditions. Ants produce a variety of complex architectures for adapting to the surrounding environment and ants’ needs. Ant mound consists of at least one pillar with a broad base tapered toward its tip. Anthill architectures have unique topological features. Mechanical strength of ant mould can be 600 times enhanced by tuning topology. Thickness and angle of pillars have huge effect on load-bearing property. The branched structures can endure larger stress and deform in the process under a volumetric pressure application, making them sacrificial units for extreme disasters like floods and earthquakes. The 3D printing experiments and FEMs simulations are needed to tackle the complex ant mound architectures and appear in good agreement, suggesting a robust design and thus the possibility of constructing anthill-inspired civil buildings with a tree-trunk-like geometry.

In this work, We combined fully atomistic molecular dynamics and finite elements simulations with mechanical testings to investigate the mechanical behavior of atomic and 3D-printed models of pentadiamond. Pentadiamond is a recently proposed new carbon allotrope, which is composed of a covalent network of pentagonal rings. Our results showed that the stress-strain behavior is almost scale-independent. The stress-strain curves of the 3D-printed structures exhibit three characteristic regions. For low-strain values, this first region presents a non-linear behavior close to zero, followed by a well-defined linear behavior. The second regime is a quasi-plastic one and the third one is densification followed by structural failures (fracture). The Young's modulus values decrease with the number of pores. The deformation mechanism is bending-dominated and different from the layer-by-layer deformation mechanism observed for other 3D-printed structures. They exhibit good energy absorption capabilities, with some structures even outperforming kevlar. Interestingly, considering the Ashby chart, 3D-printed pentadiamond lies almost on the ideal stretch and bending-dominated lines, making them promising materials for energy absorption applications.

The topologically engineered complex Schwarzites architecture has been used to build novel and unique structural components with a high specific strength. The mechanical properties of these building blocks can be further tuned, reinforcing with stronger and high surface area architecture. In the current work, we have built six different Schwarzites structures with multiple interlocked layers, which we named architecturally interlocked petal-schwarzites (AIPS). These complex structures are 3D printed into macroscopic dimensions and compressed using uniaxial compression. The experimental results show a strong dependency of mechanical response on the number of layers and topology of the layers. Fully atomistic molecular dynamics compressive simulations were also carried out, and the results are in good agreement with experimental observations. They can explain the underlying AIPS mechanism of high specific strength and energy absorption. The proposed approach opens a new perspective on developing new 3D-printed materials with tunable and enhanced mechanical properties.

We carried out fully atomistic reactive molecular dynamics simulations to study the mechanical behavior of six newly proposed hybrid schwarzite-based structures (interlocked petal-schwarzites). Schwarzites are carbon crystalline nanostructures with negative Gaussian curvature created by mapping a TPMS (Triply Periodic Minimal Surface) with carbon rings containing six to eight atoms. Our simulations have shown that petal-schwarzite structures can withstand uni-axial compressive stress up to the order of GPa and can be compressed past 50 percent strain without structural collapse. Our most resistant hierarchical structure has a calculated compressive strength of 260~GPa and specific energy absorption (SEA) of 45.95 MJ/kg, while possessing a mass density of only 685 kg/m\\(^3\\). These results show that these structures could be excellent lightweight materials for applications that require mechanical energy absorption.

Specific strength (strength/density) is a crucial factor while designing high load bearing architecture in areas of aerospace and defence. Strength of the material can be enhanced by blending with high strength component or, by compositing with high strength fillers but both the options has limitations such as at certain load, materials fail due to poor filler and matrix interactions. Therefore, researchers are interested in enhancing strength of materials by playing with topology/geometry and therefore nature is best option to mimic for structures whereas, complexity limits nature mimicked structures. In this paper, we have explored Zeolite-inspired structures for load bearing capacity. Zeolite-inspired structure were obtained from molecular dynamics simulation and then fabricated via Fused deposition Modeling. The atomic scale complex topology from simulation is experimentally synthesized using 3D printing. Compressibility of as-fabricated structures was tested in different direction and compared with simulation results. Such complex architecture can be used for ultralight aerospace and automotive parts.

Nature-occurring structures exhibiting unique topological features such as complex and gradient porosity has been the basis to create new materials and/or structures. Most studies have been focused on complex periodic porous structures but gradient porous ones have not been yet fully investigated for stable structural designs. In this work, we have proposed and tested a new approach to create cellular griding structures, in which the mass density varies from the center to the borders, i.e, a radial gradient. To create these new structures we exploited the topology of two carbon-based families with different pore sizes, the schwarzites, and schwarzynes. We created fully atomistic models that were translated into macroscale ones that were then 3D printed. The mechanical behavior of the gradient structures was investigated by molecular dynamics simulations and mechanical compression tests of the printed models. Our results show that their mechanical response can be engineered (for instance, in terms of energy absorption, ballistic performance, etc.) and can outperform their corresponding density uniform structures.

The 3D printing technology offers an innovative approach for developing energy storage devices to create facile and low-cost customized electrodes for modern electronics. Generating electric potential by moving a droplet of ionic solution over two-dimensional (2D) materials is a novel method for rain energy harvesting. This work demonstrated a liquid-solid contact electrification-based 3D printed nanogenerator where raindrop passes through the positively charged ultrathin Gadolinium Telluride (Gd2Te3) sheets. Experimental results showed that voltage as high as ~0.6 V could be generated by moving a droplet of ionic solution on the decorated 3D printed nanogenerator. The output efficiency of the nanogenerator is increased ~400% by enhancing the surface area of copious 3D printed porous structures. Density Functional Theory (DFT) calculations are done, revealing that the high electrical conductivity of (112) surface of Gd2Te3 is due to the p-type charge carriers. Additionally, we illustrate the enhancement of the output performance (~0.8V) by using a graphite rod and arbitrarily manipulating the surface charge. Therefore, this work can open up a new avenue to advance scientific research of Blue energy harvesting and tackle the energy crisis.

The human body needs to be protected from invaders in the world like microbes as WHO data shows that 17 million people die every year due to infectious diseases, source of these infectious diseases are microbes such as bacteria, fungi, protozoa, and viruses. In the last 20 years, 30 new diseases were discovered by researchers. Bacteria are the most common microbe which attacks the human body; therefore, protection from such life‐threatening microorganism is extremely necessary. Anti‐microbial drugs were discovered long back but their sustained dose only help in antibacterial effects otherwise burst release of the drug can cause side effects on the human body. To acquire sustained release drug embedded biopolymer system are most commonly practiced in this way drug release can be tuned with the degradation of biopolymers. There are many techniques for fabrication of drug/polymer system but to achieve higher efficiency rate higher surface area is required, therefore, nanotechnology utilizes for designing such high surface area materials such as nanofibers. Nanofibers can be fabricated via melt spinning, pressurized gyration, phase separation and electrospinning, out of which electrospinning is most popular due to enormous surface area, tunable fiber diameter, highly biocompatible, cost‐effectiveness. In the present chapter, we have discussed recent advances in drug embedded biodegradable electrospun nanofibers as well as non‐biodegradable electrospun nanofibers for anti‐bacterial applications.