Amir A. Zadpoor

Amir A. Zadpoor
Delft University of Technology | TU · Department of Biomechanical Engineering

PhD, MSc, BSc

About

390
Publications
245,543
Reads
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16,376
Citations
Citations since 2017
232 Research Items
14172 Citations
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Introduction
Research interests - Additive manufacturing, bioprinting, and biofabrication - Tissue biomechanics and implants - Orthopaedic biomaterials - Mechanical characterization of biomaterials and tissues - Skeletal radiology - Cellular and molecular biomechanics - Osteoarthritis and joint replacement technology - Tissue engineering and regenerative medicine
Additional affiliations
May 2020 - present
Leiden University Medical Centre
Position
  • Professor
October 2017 - December 2020
Delft University of Technology
Position
  • Chair
July 2014 - October 2017
Delft University of Technology
Position
  • Professor (Associate)
Education
May 2006 - January 2010
Delft University of Technology
Field of study
  • Mechanics of Materials
September 2004 - May 2006
Amirkabir University of Technology
Field of study
  • Biomedical Engineering
September 2000 - September 2004
Iran University of Science and Technology
Field of study
  • Mechanical Engineering

Publications

Publications (390)
Article
Background The primary aim of this study was to determine and compare the biomechanical properties of a fractured or intact rib after implant fixation on an embalmed thorax. Methods Five systems were fixated on the bilateral fractured or intact (randomly allocated) 6th to 10th rib of five post-mortem embalmed human specimens. Each rib underwent a...
Preprint
Full-text available
Living organisms have developed design principles, such as functional gradients (FGs), to interface hard materials with soft ones (e.g., bone and tendon). Mimicking such design principles can address the challenges faced when developing engineered constructs with soft-hard interfaces. To date, implementing these FG design principles has been primar...
Article
Origami Lattices Folding of flat sheets into 3D structures is a promising approach for the fabrication of functionalized metamaterials. Inspired by sheet metal forming, Teunis van Manen and co‐workers in article number 2203603 develop an automated folding method for the folding of stiff lattice structures comprising large numbers of small interconn...
Article
Objective: To examine the association between 3D patellar shape and 1) isolated MRI-based patellofemoral osteoarthritis (PFOA), 2) the morphological features of PFOA, and 3) the clinical symptoms of PFOA. Design: Magnetic resonance imaging (MRI) data from 66 women with isolated MRI-based PFOA and 66 age- and BMI-matched healthy women were select...
Article
Interactions of Preosteoblasts Physical patterns are potential surface cues for promoting osteogenic differentiation of stem cells and improving osseointegration of orthopedic implants. Fluidic force microscopy and atomic force microscopy are used to quantitatively investigate the early interaction of preosteoblasts with 3D‐printed patterns having...
Preprint
Practical applications of mechanical metamaterials often involve solving inverse problems where the objective is to find the (multiple) microarchitectures that give rise to a given set of properties. The limited resolution of additive manufacturing techniques often requires solving such inverse problems for specific sizes. One should, therefore, fi...
Article
Full-text available
Background Nuclear factor erythroid 2–related factor 2 (Nrf2) is a crucial transcription factor for cellular redox homeostasis. The association of Nrf2 with elderly female osteoporotic has yet to be fully described. The aim was to elucidate a potential age-dependent Nrf2 contribution to female osteoporosis in mice. Methods Eighteen female wild typ...
Article
Physical patterns represent potential surface cues for promoting osteogenic differentiation of stem cells and improving osseointegration of orthopedic implants. Understanding the early cell–surface interactions and their effects on late cellular functions is essential for a rational design of such topographies, yet still elusive. In this work, flui...
Article
Full-text available
Folding nanopatterned flat sheets into complex 3D structures enables the fabrication of meta‐biomaterials that combine a rationally designed 3D architecture with nanoscale surface features. Self‐folding is an attractive approach for realizing such materials. However, self‐folded lattices are generally too compliant as there is an inherent competiti...
Article
Full-text available
Implant-associated infections are highly challenging to treat, particularly with the emergence of multidrug-resistant microbials. Effective preventive action is desired to be at the implant site. Surface biofunctionalization of implants through Ag-doping has demonstrated potent antibacterial results. However, it may adversely affect bone regenerati...
Article
Full-text available
Black Ti (bTi) surfaces comprising high aspect ratio nanopillars exhibit a rare combination of bactericidal and osteogenic properties, framing them as cell-instructive meta-biomaterials. Despite the existing data indicating that bTi surfaces induce osteogenic differentiation in cells, the mechanisms by which this response is regulated are not fully...
Article
Three‐dimensional (3D) bioprinting is usually implemented on flat surfaces, posing serious limitations in the fabrication of multilayered curved constructs. Four‐dimensional (4D) bioprinting, combining 3D bioprinting with time‐dependent stimuli‐induced transformation, enables the fabrication of shape‐changing constructs. Here, we report a 4D biofab...
Article
Full-text available
Nanoparticles (NPs) have high multifunctional potential to simultaneously enhance implant osseointegration and prevent infections caused by antibiotic-resistant bacteria. Here, we present the first report on using plasma electrolytic oxidation (PEO) to incorporate different combinations of reduced graphene oxide (rGO) and silver (Ag) NPs on additiv...
Article
Full-text available
Additive manufacturing (AM, also known as 3D printing) is an advanced manufacturing technique that has enabled progress in the design and fabrication of customised or patient-specific (meta-)biomaterials and biomedical devices (e.g., implants, prosthetics, and orthotics) with complex internal microstructures and tuneable properties. In the past few...
Article
The treatment of femoral nonunion with large segmental bone defect is still challenging. Although magnesium alloys have been considered potential materials for such a treatment, their application is limited by their fast degradation. Adding bioceramic particles into magnesium to form Mg-matrix composites is a promising strategy to adjust their biod...
Article
Full-text available
Emerging multi-material 3D printing techniques enables the rational design of metamaterials with not only complex geometries but also arbitrary distributions of multiple materials within those geometries, yielding unique combinations of elastic properties. However, discovering the rare designs that lead to highly unusual combinations of material pr...
Article
Full-text available
4D printing of flat sheets that self-fold into architected 3D structures is a powerful origami-inspired approach for the fabrication of multi-functional devices and metamaterials. However, the opposite stiffness requirements for the folding process and the subsequent loadbearing of 3D structures impose an intrinsic limitation in designing self-fold...
Article
Full-text available
Bio-inspired composites are a great promise for mimicking the extraordinary and highly efficient properties of natural materials. Recent developments in voxel-by-voxel 3D printing have enabled extreme levels of control over the material deposition, yielding complex micro-architected materials. However, design complexity, very large degrees of freed...
Preprint
Full-text available
Machine-matter, of which mechanical metamaterials and meta-devices are important sub-categories, is emerging as a major paradigm for designing advanced functional materials. Various exciting applications of these concepts have been recently demonstrated, ranging from exotic mechanical properties to device-like and adaptive functionalities. The vast...
Preprint
Full-text available
Durable interfacing of hard and soft materials is a major design challenge caused by the ensuing stress concentrations. In nature, soft-hard interfaces exhibit remarkable mechanical performance, with failures rarely happening at the interface but in the hard or soft material. This superior performance is mechanistically linked to such design featur...
Article
Full-text available
Advanced additive manufacturing techniques have been recently used to tackle the two fundamental challenges of biodegradable Fe-based bone-substituting materials, namely low rate of biodegradation and insufficient bioactivity. While additively manufactured porous iron has been somewhat successful in addressing the first challenge, the limited bioac...
Article
Full-text available
Recent advances in 3D printable micro-architected materials offer unprecedented possibilities for the development of highly tailored orthopaedic implants. These devices, which are typically made from fully solid materials, significantly alter load transmission to the surrounding bone tissue, potentially leading to interface instability and bone res...
Article
We designed and fabricated a simple setup for the controlled crumpling of nanopatterned, surface-porous flat metallic sheets for the fabrication of volume-porous biomaterials and showed that crumpling can be considered as an efficient alternative to origami-inspired folding. Before crumpling, laser cutting was used to introduce pores to the sheets....
Article
Modulation of the immune response following the implantation of biomaterials can have beneficial effects on bone regeneration. This involves complex interactions between the inflammatory and osteogenic cells. Therefore, the study of cell-cell interactions using direct co-culture models integrated with biomaterials is of great interest. This researc...
Article
Full-text available
The reconstruction of large mandibular defects with optimal aesthetic and functional outcomes remains a major challenge for maxillofacial surgeons. The aim of this study was to design patient-specific mandibular reconstruction implants through a semi-automated digital workflow and to assess the effects of topology optimization on the biomechanical...
Preprint
Full-text available
Bio-inspired composites are a great promise for mimicking the extraordinary and highly efficient properties of natural materials. Recent developments in voxel-by-voxel 3D printing have enabled extreme levels of control over the material deposition, yielding complex micro-architected materials. However, spatial complexity makes it a formidable chall...
Preprint
Full-text available
Emerging multi-material 3D printing techniques have paved the way for the rational design of metamaterials with not only complex geometries but also arbitrary distributions of multiple materials within those geometries. Varying the spatial distribution of multiple materials gives rise to many interesting and potentially unique combinations of aniso...
Article
Full-text available
The rational design of bone-substituting biomaterials is relatively complex because they should meet a long list of requirements for optimal performance. Meta-biomaterials are micro-architected materials that hold great promise for meeting those requirements as they offer a unique combination of mechanical, mass-transport, and biological properties...
Article
Full-text available
Developing high-throughput nanopatterning techniques that also allow for precise control over the dimensions of the fabricated features is essential for the study of cell-nanopattern interactions. Here, we developed a process that fulfills both of these criteria. Firstly, we used electron-beam lithography (EBL) to fabricate precisely controlled arr...
Article
Full-text available
Porous biodegradable Mg and its alloys are considered to have a great potential to serve as ideal bone substitutes. The recent progress in additive manufacturing (AM) has prompted its application to fabricate Mg scaffolds with geometrically ordered porous structures. Extrusion-based AM, followed by debinding and sintering, has been recently demonst...
Article
Full-text available
Additively manufacturing of porous iron offers a unique opportunity to increase its biodegradation rate by taking advantage of arbitrarily complex porous structures. Nevertheless, achieving the required biodegradation profile remains challenging due to the natural passivation of iron that decrease the biodegradation rate. Moreover, the biocompatibi...
Article
Full-text available
Bone-to-soft tissue interfaces are responsible for transferring loads between tissues with significantly dissimilar material properties. The examples of connective soft tissues are ligaments, tendons, and cartilages. Such natural tissue interfaces have unique microstructural properties and characteristics which avoid the abrupt transitions between...
Preprint
Full-text available
Folding nanopatterned flat sheets into complex 3D structures enables the fabrication of meta-biomaterials that combine a rationally designed 3D architecture (e.g., to tune mechanical and mass transport properties) with nanoscale surface features (e.g., to guide the differentiation of stem cells). Self-folding is an attractive approach for realizing...
Article
Full-text available
The fatigue performance of additively manufactured auxetic meta-biomaterials made from commercially pure titanium has been studied only recently. While certain assumptions have been made regarding the mechanisms underlying their fatigue failure, the exact mechanisms are not researched yet. Here, we studied the mechanisms of crack formation and prop...
Conference Paper
Quantitative Magnetic Resonance Imaging (MRI) can enable early diagnosis of knee cartilage damage if imaging is performed during the application of load. Mechanical loading via ropes, pulleys and suspended weights can be obstructive and require adaptations to the patient table. In this paper, a new lightweight MRI-compatible elastic loading mechani...
Article
Additively manufactured (AM) micro-architected biodegradable metals offer a unique combination of properties that are ideal for bone regeneration including biocompatibility, a fully interconnected porous structure, and the possibility to fully regenerate bony defects with native tissue upon biodegradation. Currently, the mechanical properties of AM...
Article
Additively manufactured (AM) biodegradable magnesium (Mg) scaffolds with precisely controlled and fully interconnected porous structures offer unprecedented potential for temporary bone substitution and for bone regeneration in critical-sized bone defects....
Article
Full-text available
The treatment of articular cartilage defects remains a significant clinical challenge. This is partially due to current tissue engineering strategies failing to recapitulate native organization. Articular cartilage is a graded tissue with three layers exhibiting different cell densities: the superficial zone having the highest density and the deep...
Article
Full-text available
The design of advanced functional devices often requires the use of intrinsically curved geometries that belong to the realm of non‐Euclidean geometry and remain a challenge for traditional engineering approaches. Here, it is shown how the simple deflection of thick meta‐plates based on hexagonal cellular mesostructures can be used to achieve a wid...
Article
Full-text available
Rapid advances in additive manufacturing have kindled widespread interest in the rational design of metamaterials with unique properties over the past decade. However, many applications require multi‐physics metamaterials, where multiple properties are simultaneously optimized. This is challenging since different properties, such as mechanical and...
Article
Full-text available
In article number 2101373, Sebastien J. P. Callens and co‐workers describe a novel parametric approach to designing biphasic metamaterials based on minimal surfaces, which is demonstrated using multi‐material 3D printing. This approach enables independent tuning of the mechanical and mass transport properties, a feature that is highly relevant in m...
Article
Full-text available
The surface topography of implantable devices is of crucial importance for guiding the cascade of events that starts from the initial contact of the cells with the surface and continues until the complete integration of the device in its immediate environment. There is, however, limited quantitative information available regarding the relationships...
Article
Full-text available
Porous biomaterials are often used to treat large bony defects or fractured vertebras. Most of such biomaterials are made of metals and their alloys and have a pre-defined, fixed shape. Due to their predefined fixed shape, however, they are not suitable for implantation through minimally invasive surgical procedures. To overcome this problem, we de...
Article
Full-text available
Additively manufactured biodegradable porous iron has been only very recently demonstrated. Two major limitations of such a biomaterial are very low biodegradability and incompatibility with magnetic resonance imaging (MRI). Here, we present a novel biomaterial that resolves both of those limitations. We used extrusion-based 3D printing to fabricat...
Article
Full-text available
A solution for challenging hip dysplasia surgery could be a patient-specific 3D-printed shelf implant that is positioned extra-articular and restores the dysplastic acetabular rim to normal anatomical dimensions. The anatomical correction and biomechanical stability of this concept were tested in a canine model that, like humans, also suffers from...
Article
Full-text available
The surface topography of engineered extracellular matrices is one of the most important physical cues regulating the phenotypic polarization of macrophages. However, not much is known about the ways through which submicron (i.e., 100-1000 nm) topographies modulate the polarization of macrophages. In the context of bone tissue regeneration, it is w...
Preprint
Full-text available
4D printing of flat sheets that self-fold into architected 3D structures is a powerful origami-inspired approach for the fabrication of multi-functional devices and metamaterials. The possibility to endow the initially flat sheet with a variety of surface-related functionalities provides the means to simultaneously achieve multi-functional performa...
Article
Full-text available
Shape-shifting materials are a powerful tool for the fabrication of reconfigurable materials. Upon activation, not only a change in their shape but also a large shift in their material properties can be realized. As compared with the 4D printing of 2D-to-3D shape-shifting materials, the 4D printing of reconfigurable (i.e., 3D-to-3D shape-shifting)...
Article
Full-text available
The organization and shape of the microstructural elements of trabecular bone govern its physical properties, are implicated in bone disease, and serve as blueprints for biomaterial design. To devise fundamental structure-property relationships and design truly bone-mimicking biomaterials, it is essential to characterize trabecular bone structure f...
Article
Exploiting the potential of the small-scale pillars of black titanium is proved to be a promising strategy for directing the fate of the cells and bacteria. In article number 2100706, Khashayar Modaresifar and co-workers use different combinations of pillars' design parameters (e.g., height and arrangement) to reach a certain gain which is, ideally...
Article
Full-text available
Aseptic loosening of a permanent prosthesis remains one of the most common reasons for bone implant failure. To improve the fixation between implant and bone tissue as well as enhance blood vessel formation, bioactive agents are incorporated into the surface of the biomaterial. This study reviews and compares five bioactive elements (copper, magnes...
Article
Full-text available
Mechanical metamaterials are advanced engineering materials that exhibit unusual properties that cannot be found in nature. The elastic properties (i.e., elastic modulus and Poisson's ratio) of mechanical metamaterials can be tuned by changing the geometry of their fundamental unit cells. This allows for the design of metamaterial lattices with tar...
Preprint
Full-text available
Mechanical metamaterials owe their extraordinary properties and functionalities to their micro-/nanoscale design of which shape, including both geometry and topology, is perhaps the most important aspect. 4D printing enables programmed, predictable, and precise change in the shape of mechanical metamaterials to achieve multi-functionality, adaptive...
Article
Full-text available
Despite the potential of small‐scale pillars of black titanium (bTi) for killing the bacteria and directing the fate of stem cells, not much is known about the effects of the pillars’ design parameters on their biological properties. Here, three distinct bTi surfaces are designed and fabricated through dry etching of the titanium, each featuring di...
Article
Recent insights suggest that the osteochondral interface plays a central role in maintaining healthy articulating joints. Uncovering the underlying transport mechanisms is key to the understanding of the cross-talk between articular cartilage and subchondral bone. Here, we describe the mechanisms that facilitate transport at the osteochondral inter...
Article
Full-text available
Additive manufacturing (AM) offers great design freedom that enables objects with desired unique and complex geometry and topology to be readily and cost-effectively fabricated. The overall benefits of AM are well known, such as increased material and resource efficiency, enhanced design and production flexibility, the ability to create porous stru...
Article
Full-text available
Patients receiving orthopedic implants are at risk of implant-associated infections (IAI). A growing number of antibiotic-resistant bacteria threaten to hamper the treatment of IAI. The focus has, therefore, shifted towards the development of implants with intrinsic antibacterial activity to prevent the occurrence of infection. The use of Ag, Cu, a...
Article
Full-text available
Treating large bone defects is still a clinical challenge without perfect solution, mainly due to the unavailability of suitable bone implants. Additively manufactured (AM) absorbable porous metals provide unparalleled opportunities to realize the challenging requirements for bone-mimetic implants. Firstly, multi-scale geometries of such implants c...
Conference Paper
Purpose: Alterations in bone shape are not only associated with the presence of radiographic OA, they are predictive of tibiofemoral OA onset and have even been proposed as a biomarker for tibiofemoral OA progression. Such biomarkers for early OA detection and progression are essential in the developing successful and early OA interventions. There...
Article
We studied the three-dimensional (3-D) shape variations and symmetry of the lunate to evaluate whether a contralateral shape-based approach to design patient-specific implants for treatment of Kienböck’s disease is accurate. A 3-D statistical shape model of the lunate was built using the computed tomography scans of 54 lunate pairs and shape symmet...