Biomaterials Design for Human Body Repair

The global clinical demand for biomaterials is constantly increasing due to the aging population [1,2]. Biomaterials are biocompatible materials made of metal [3,4,5], polymer [6,7,8], bioactive glass [9,10,11], ceramic [12,13,14,15,16,17] or a composite of these materials. The International Union of Pure and Applied Chemistry (IUPAC) defines biocompatibility as the ability of a material to be in contact with a biological system without producing an adverse effect [18,19,20,21,22,23]. Academic and industrial research permanently develops new biomaterials with extended lifespans and improved properties to repair or replace tissue functions of the body. Implanted materials need specific biological, physical, chemical, and mechanical properties to interact appropriately with the physiological environment. The biomedical applications of biomaterials include, but are not limited to, joint replacements, bone implants, intraocular lenses, artificial organs, artificial ligaments and tendons, dental implants, blood vessel prostheses, heart valves, skin repair, cochlear implants, drug delivery systems, stents, nerve conduits, surgical sutures, pins and screws for fracture stabilization, and surgical mesh.

This topical collection gathers feature articles and reviews presenting the latest achievements in the field and the next challenges for future investigations of the design and applications of biomaterials (Figure 1).

In their article, Pires et al. designed a low-power device for non-invasive blood glucose monitoring [24]. The blood glucose concentration is measured with a near-infrared sensor integrated into a small box placed on the tip of the patient’s finger. This innovative device provides high-precision measurements.

In another article, Andreucci et al. describe the use of 3D images from CT scans of patients and 3D printing (also known as additive manufacturing) for mandibular osteotomy [25]. This method of maxillofacial surgery aims to readjust the position of the lower jaw (mandible). The material used to produce the 3D-printed craniofacial implant is nylon, a bioactive polymer material with properties close to bone.

The article by Chatzipapas et al. describes an innovative 3D printing method to produce a biocompatible artificial liver including veins and arteries [26]. Polylactic acid (PLA) is used to create a mold of a liver that is filled with biocompatible light-bodied silicone (polysiloxane). Molds of the veins and arteries are printed using polyvinyl alcohol (PVA). The method is relevant in producing artificial livers with expected applications in medical training, personalized medicine, and organ transplantation.

In another article, Turek et al. describe a reverse engineering (RE) method to accurately reconstruct the geometry of three-dimensional computer-aided designed (3D CAD) models [27]. They show the influence of the measurement parameters, the accuracy of the data fitting, and the parameterization method on the precision of the model. Their innovative method produces accurate bone models (hip bone and femur) with a ±0.1 mm deviation.

Mejía Rodríguez et al. use finite element analysis (FEA) to study polymeric cranial implants under different design parameters [28]. They describe the mechanical behavior of poly(methyl methacrylate) (PMMA) and polyether ether ketone (PEEK) and discuss the impact of thickness and perforations used in surgical procedures. They conclude that both PMMA and PEEK biomaterials are suitable for producing cranial implants because they withstand deformation in the normal direction.

Another article by Pais et al. reports a computational analysis of the mechanical behavior of tibial implants used in total knee arthroplasty (TKA) [29]. They describe the influence of the knee joint implant properties on the bone remodeling process of the tibia after implantation. The results show the impact of the length of the tibial stem on the maximum stress and displacement distributions in the proximal tibia.

Jia Uddin’s article describes a new method using CT scans and histopathological images to improve lung cancer detection and classification [30]. Deep learning technologies are used to improve the precision and reliability of lung cancer diagnostics for early detection and treatment.

In their article, Islam and Tarique studied the performance and optimization of gammatone filters used to design cochlear implants [31]. This theoretical research evaluates the impact of several parameters such as the filter bandwidth, signal frequency, and interferences on the cochlear implant performance.

Efstathiadis et al. investigate the mechanical behavior of polylactic acid (PLA) specimens made by using a 3D printing process called fused filament fabrication (FFF) [32]. The specimens are printed in a biomimetic Voronoi structure inspired by the microstructure of the shell of the sea urchin Paracentrotus lividus. The experimental results of this biomimetic design strategy are compared with computational results obtained by finite element analysis.

The research proposed by Bertrand et al. focuses on the mechanical strength of calcium phosphate cement scaffolds produced by 3D printing [33]. This biomaterial is expected to be used for bone tissue repair. The authors describe the influence of the number of printed layers and the influence of the needle’s inner diameter on the compressive strength of the 3D-printed bioceramic scaffolds.

The tribological study by Andreucci et al. describes the use of blood as a biological lubricant for drilling and screwing implants into bone [34]. The viscosity of the blood plasma combined with the elastic properties provided by the red blood cells improves the sliding and frictional interfaces between the bone and implant surfaces.

Nuswantoro et al. comprehensively review various types of bio-based adhesives used in orthopedic applications [35]. They are polymer materials with powerful properties for bone fracture healing. In addition to strong adhesion characteristics, bio-based adhesives exhibit biocompatibility, biodegradability, large molecular weight, excellent resorbability, ease of use, and low immunoreactivity.