Implantable Applications Research Articles

A ceria/calcium-phosphate functional composite coating on magnesium alloy for enhanced adhesion strength, corrosion resistance, and biocompatibility

Magnesium (Mg) and its alloys have been regarded as potential orthopedic implant materials due to their suitable properties but face challenges due to rapid biocorrosion and insufficient bio-functionality, necessitating surface treatment to mitigate dysfunction. In this work, a two-step electrodeposition was employed to construct a ceria/calcium-phosphate (Ce/Ca-P) composite coating on Mg alloys. This construction approach endows multi-functions of the coating. The ceria interlayer ameliorates adhesion strength. The pin-like structure on the outer layer of the Ce/Ca-P coating enhances the antibacterial capabilities of the coating in the early stages of the implantation. The calcium-phosphate outer layer and the ceria interlayer induce the deposition of calcium and phosphate ions promoting bone healing in the mid-term. The introduction of the ceria interlayer significantly reduces the corrosion rate of the Mg alloy by 86.7% improving the corrosion resistance of the alloy, which is of great significance to maintain the service reliability of the device during the long-term service period. The results indicate that the Ce/Ca-P coating exhibits good hemocompatibility and cytocompatibility. This type of developed coating with anti-corrosive and bio-functionalized capability helpfully advances the application of Mg-based bone implants.

Tuneable mechanical performance and reusability of 4D-printed heterogeneous metamaterials using shape memory biomass-derived polymer

ABSTRACT Herein, hybrid triply periodic minimal surfaces (TPMS) metamaterials were structurally designed and additively manufactured via 4D printing using a biomass-derived shape memory polymer. Two TPMS topologies including gyroid and diamond with homogeneous and graded structures were separately generated by adjusting the C parameter. The mechanical performance and deformation behaviour between the uniform and graded structures were compared, and the compressive shaping-recovery cycles were conducted. The results showed that the gyroid (C:0.7→0.4) and diamond (C:0.7→0.4) samples exhibited superior reusability to the uniform counterparts. Subsequently, heterogeneous metamaterials assembled by gyroid and diamond subsections were established and 4D-printed. It was observed that both the yielding and shape recovery were preferred occurring in the gyroid part, while the diamond subsection played a stronger supporting effect. Therefore, the compressive performance and deformation mode could be feasibly tuned by the hybridisation of TPMS, which broadened the functional and sustainable applications in energy absorption, intelligent protection and medical implants.

All-Fiber Flexible Electrochemical Sensor for Wearable Glucose Monitoring.

Wearable sensors, specifically microneedle sensors based on electrochemical methods, have expanded extensively with recent technological advances. Today's wearable electrochemical sensors present specific challenges: they show significant modulus disparities with skin tissue, implying possible discomfort in vivo, especially over extended wear periods or on sensitive skin areas. The sensors, primarily based on polyethylene terephthalate (PET) or polyimide (PI) substrates, might also cause pressure or unease during insertion due to the skin's irregular deformation. To address these constraints, we developed an innovative, wearable, all-fiber-structured electrochemical sensor. Our composite sensor incorporates polyurethane (PU) fibers prepared via electrospinning as electrode substrates to achieve excellent adaptability. Electrospun PU nanofiber films with gold layers shaped via thermal evaporation are used as base electrodes with exemplary conductivity and electrochemical catalytic attributes. To achieve glucose monitoring, gold nanofibers functionalized by gold nanoflakes (AuNFs) and glucose oxidase (GOx) serve as the working electrode, while Pt nanofibers and Ag/AgCl nanofibers serve as the counter and reference electrode. The acrylamide-sodium alginate double-network hydrogel synthesized on electrospun PU fibers serves as the adhesive and substance-transferring layer between the electrodes. The all-fiber electrochemical sensor is assembled layer-by-layer to form a robust structure. Given the stretchability of PU nanofibers coupled with a high specific surface area, the manufactured porous microneedle glucose sensor exhibits enhanced stretchability, superior sensitivity at 31.94 μA (lg(mM))-1 cm-2, a broad detection range (1-30 mM), and a significantly low detection limit (1 mM, S/N = 3), as well as satisfactory biocompatibility. Therefore, the novel electrochemical microneedle design is well-suited for wearable or even implantable continuous monitoring applications, thereby showing promising significant potential within the global arena of wearable medical technology.

Recent Progress in Organic Electrochemical Transistor-Structured Biosensors.

The continued advancement of organic electronic technology will establish organic electrochemical transistors as pivotal instruments in the field of biological detection. Here, we present a comprehensive review of the state-of-the-art technology and advancements in the use of organic electrochemical transistors as biosensors. This review provides an in-depth analysis of the diverse modification materials, methods, and mechanisms utilized in organic electrochemical transistor-structured biosensors (OETBs) for the selective detection of a wide range of target analyte encompassing electroactive species, electro-inactive species, and cancer cells. Recent advances in OETBs for use in sensing systems and wearable and implantable applications are also briefly introduced. Finally, challenges and opportunities in the field are discussed.

Bioinspired Self-Adhesive Multifunctional Lubricated Coating for Biomedical Implant Applications.

In the realm of clinical applications, the concern surrounding biomedical device-related infections (BDI) is paramount. To mitigate the risk associated with BDI, enhancing surface characteristics such as lubrication and antibacterial efficacy is considered as a strategic approach. This study delineated the synthesis of a multifunctional copolymer, embodying self-adhesive, lubricating, and antibacterial properties, achieved through free radical polymerization and a carbodiimide coupling reaction. The copolymer was adeptly modified on the surface of stainless steel 316L (SS316L) substrates by employing a facile dip-coating technique. Comprehensive characterizations were performed by using an array of analytical techniques including Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, optical interferometry, scanning electron microscopy, and atomic force microscopy. Nanoscale tribological assessments revealed a notable reduction in the value of the friction coefficient of the copolymer-coated SS316L substrates compared to bare SS316L samples. The coating demonstrated exceptional resistance to protein adsorption, as evidenced in protein contamination models employing bovine serum albumin and fibrinogen. The bactericidal efficacy of the copolymer-modified surfaces was significantly improved against pathogenic strains such as Staphylococcus aureus and Escherichia coli. Additionally, in vitro evaluations of blood compatibility and cellular compatibility underscored the remarkable anticoagulant performance and biocompatibility. Collectively, these findings indicated that the developed copolymer coating represented a promising candidate, with its facile modification approach, for augmenting lubrication and antifouling properties in the field of biomedical implant applications.

Triggerable Patches for Medical Applications.

Medical patches have garnered increasing attention in recent decades for several diagnostic and therapeutic applications. Advancements in material science, manufacturing technologies, and bioengineering have significantly widened their functionalities, rendering them highly versatile platforms for wearable and implantable applications. Of particular interest are triggerable patches designed for drug delivery and tissue regeneration purposes, whose action can be controlled by an external signal. Stimuli-responsive patches are particularly appealing as they may enable a high level of temporal and spatial control over the therapy, allowing high therapeutic precision and the possibility to adjust the treatment according to specific clinical and personal needs. This review aims to provide a comprehensive overview of the existing extensive literature on triggerable patches, emphasizing their potential for diverse applications and highlighting the strengths and weaknesses of different triggering stimuli. Additionally, the current open challenges related to the design and use of efficient triggerable patches, such as tuning their mechanical and adhesive properties, ensuring an acceptable trade-off between smartness and biocompatibility, endowing them with portability and autonomy, accurately controlling their responsiveness to the triggering stimulus and maximizing their therapeutic efficacy, are reviewed.

Clinical Applicability of Autologous Chondrocyte Implantation for the Treatment of Osteochondral Defects: A Meta-analysis.

Osteoarthritis and other joint disorders are the leading cause of disability in the elderly and the treatment of joint lesions is challenging. Autologous chondrocyte implantation (ACI) has been reported with variable effects for the treatment of osteochondral and other joint lesions. In this study, we performed a meta-analysis of the recent literature to determine the clinical applicability of ACI for osteochondral defects. A meta-analysis was performed on the recent literature showing the effects of ACI on osteochondral defects. The PUBMED, ScienceDirect and Google Scholar databases were used to identify eligible studies from Jan 2010 to Sep 2022. Both fixed and random models of meta-analysis were applied with all reported scoring systems to quantify the effectiveness of ACI on osteochondral defects. The pool data of 965 patients as a case series after ACI from a fixed model showed a significant improvement in the osteochondral defects (odds ratio = 8.75, 95%CI = 7.127 to 10.743, p = 0.000). These results were further verified by a random model of meta-analysis. The data also showed a substantial heterogeneity among the studies used in the meta-analysis (Q-value = 160.41, I-squared = 87.53, p = 0.000). Furthermore, this meta-analysis also compared different ACI procedures with different scoring systems but the overall outcome remains the same as ACI was found to be useful for the healing of the osteochondral defects. This meta-analysis of 965 case series revealed that the ACI markedly improved the damage osteochondral defects scores but the optimal treatment is still controversial, therefore further studies are needed to validate these findings in a clinical setting.

Determining carrier frequency for implantable human body communication based on transmission efficiency–electromagnetic interference trade-off

This study proposes a novel methodology for determining the optimal carrier frequency for implantable human body communication (HBC) by focusing on the trade-off between transmission efficiency and electromagnetic interference (EMI) robustness. Traditional radio communication technologies use high-frequency bands, which pose some challenges, such as increased power consumption, EMI with other devices, and security risks. Implantable HBC is a promising alternative, wherein the human body is used as a transmission medium. Through phantom experiments simulating the human abdomen, we assess the transmission characteristics of implantable HBC between an abdominal neurostimulator and an external controller across a frequency range of 1–100 MHz. Results revealed that maximum transmission gain was achieved at 37.2 MHz. Moreover, rapid signal attenuation occurred beyond a minimal distance from the skin, indicating enhanced communication efficiency, reduced EMI, and enhanced information security. An evaluation index (EI) was also proposed to quantitatively assess the balance between transmission efficiency and EMI and determine an appropriate carrier frequency for specific implantable HBC applications. This study advances the field of implantable medical devices by optimizing communication performance while addressing key challenges in EMI and security.

Hermetic, Hybrid Multilayer, Sub‐5µm‐Thick Encapsulations Prepared with Vapor‐Phase Infiltration of Metal Oxides in Conformal Polymers for Flexible Bioelectronics

AbstractReliable long‐term function is crucial for flexible and soft bioelectronics. Mechanical defects and permeation of water molecules across the various device layers are the prime drivers of failure, and particularly in applications requiring continuous contact with biofluids (i.e. for implantable applications). To address demanding needs of miniaturization, mechanical compliance and water impermeability, ultra‐thin high‐barrier encapsulations are a promising way to improve device reliability. In this work, the encapsulation properties of vapour phase infiltration (VPI) of inorganic Al2O3 layers deposited by atomic layer deposition (ALD), as bilayers with TiO2, onto polyimide and parylene C organic substrates are investigated. The layers are grown in a single reactor and the infiltration is performed in a single process, with a resulting nanometric infiltration depth. Mechanical integrity and hermeticity are characterized through tensile fragmentation tests and accelerated aging tests. Flexible Magnesium sensors monitor water vapor permeability in situ. A remarkable improvement in the crack onset strain (∽2.56 times), interfacial shear strength (∽2.1 times), water vapour transmission rate (∽5.2 times) and lifetime performance (∽7.1 times) is achieved, compared to the non‐infiltrated ALD coatings. Pluri‐infiltrated multilayers are proposed as alternatives to conventional coatings. This work is envisioned to accelerate research progress on hermetic packaging of flexible bioelectronics.

Development and Evaluation of an AZ31 Magnesium Alloy and Eggshell Powder Composite for Orthopedic Surgical Implants

This research investigates the development and evaluation of a novel composite material composed of AZ31 magnesium alloy and eggshell powder, designed for use in surgical bone implants. The primary objective is to enhance the mechanical properties and biocompatibility of AZ31 by incorporating eggshell powder, which is known for its hardness and strength. The composite is fabricated using the stir casting technique, where the molten magnesium is mixed with finely ground eggshell powder to achieve uniform dispersion. The resulting samples are subjected to rigorous mechanical testing, including tensile and compressive strength evaluations, as well as hardness measurements. Additionally, the internal structure and particle distribution of the composite are analyzed using scanning electron microscopy and X-ray diffraction, respectively. This study aims to provide a comprehensive understanding of the material properties and structural characteristics of the composite, with a focus on its potential applications in orthopedic load-bearing implants and fixation devices, such as bone plates, joint replacements, screws, rods, dental implants, and cardiac stents. The findings are expected to contribute to the development of improved biomaterials for medical applications, leveraging the unique benefits of both magnesium alloy and eggshell powder.

Application of zygomatic implants in patients with maxillary bone atrophy

Application of zygomatic implants in patients with maxillary bone atrophy

Development of Novel Antibacterial Ti-Nb-Ga Alloys with Low Stiffness for Medical Implant Applications.

With the rising demand for medical implants and the dominance of implant-associated failures including infections, extensive research has been prompted into the development of novel biomaterials that can offer desirable characteristics. This study develops and evaluates new titanium-based alloys containing gallium additions with the aim of offering beneficial antibacterial properties while having a reduced stiffness level to minimise the effect of stress shielding when in contact with bone. The focus is on the microstructure, mechanical properties, antimicrobial activity, and cytocompatibility to inform the suitability of the designed alloys as biometals. Novel Ti-33Nb-xGa alloys (x = 3, 5 wt%) were produced via casting followed by homogenisation treatment, where all results were compared to the currently employed alloy Ti-6Al-4V. Optical microscopy, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) results depicted a single beta (β) phase microstructure in both Ga-containing alloys, where Ti-33Nb-5Ga was also dominated by dendritic alpha (α) phase grains in a β-phase matrix. EDS analysis indicated that the α-phase dendrites in Ti-33Nb-5Ga were enriched with titanium, while the β-phase was richer in niobium and gallium elements. Mechanical properties were measured using nanoindentation and microhardness methods, where the Young's modulus for Ti-33Nb-3Ga and Ti-33Nb-5Ga was found to be 75.4 ± 2.4 and 67.2 ± 1.6 GPa, respectively, a significant reduction of 37% and 44% with respect to Ti-6Al-4V. This reduction helps address the disproportionate Young's modulus between titanium implant components and cortical bone. Importantly, both alloys successfully achieved superior antimicrobial properties against Gram-negative P. aeruginosa and Gram-positive S. aureus bacteria. Antibacterial efficacy was noted at up to 90 ± 5% for the 3 wt% alloy and 95 ± 3% for the 5 wt% alloy. These findings signify a substantial enhancement of the antimicrobial performance when compared to Ti-6Al-4V which exhibited very small rates (up to 6.3 ± 1.5%). No cytotoxicity was observed in hGF cell lines over 24 h. Cell morphology and cytoskeleton distribution appeared to depict typical morphology with a prominent nucleus, elongated fibroblastic spindle-shaped morphology, and F-actin filamentous stress fibres in a well-defined structure of parallel bundles along the cellular axis. The developed alloys in this work have shown very promising results and are suggested to be further examined towards the use of orthopaedic implant components.

Investigating the Feasibility and Performance of Hybrid Overmolded UHMWPE 3D-Printed PEEK Structural Composites for Orthopedic Implant Applications: A Pilot Study.

Ultra-high-molecular-weight polyethylene (UHMWPE) components for orthopedic implants have historically been integrated into metal backings by direct-compression molding (DCM). However, metal backings are costly, stiffer than cortical bone, and may be associated with medical imaging distortion and metal release. Hybrid-manufactured DCM UHMWPE overmolded additively manufactured polyetheretherketone (PEEK) structural components could offer an alternative solution, but are yet to be explored. In this study, five different porous topologies (grid, triangular, honeycomb, octahedral, and gyroid) and three surface feature sizes (low, medium, and high) were implemented into the top surface of digital cylindrical specimens prior to being 3D printed in PEEK and then overmolded with UHMWPE. Separation forces were recorded as 1.97-3.86 kN, therefore matching and bettering the historical industry values (2-3 kN) recorded for DCM UHMWPE metal components. Infill topology affected failure mechanism (Type 1 or 2) and obtained separation forces, with shapes having greater sidewall numbers (honeycomb-60%) and interconnectivity (gyroid-30%) through their builds, tolerating higher transmitted forces. Surface feature size also had an impact on applied load, whereby those with low infill-%s generally recorded lower levels of performance vs. medium and high infill strategies. These preliminary findings suggest that hybrid-manufactured structural composites could replace metal backings and produce orthopedic implants with high-performing polymer-polymer interfaces.

Surface modification of Ti6Al4V screws Using HA-mixed EDCLT for applications of dental implants

Surface modification of Ti6Al4V screws Using HA-mixed EDCLT for applications of dental implants

Synthesis of Ag-Doped Tetrahedral Amorphous Carbon Coatings and Their Antibiofilm Efficacy for Medical Implant Application.

Tetrahedral amorphous carbon (taC) is a hydrogen-free carbon with extensive properties such as hardness, optical transparency, and chemical inertness. taC coatings have attracted much attention in recent times, as have coatings doped with a noble metal. A known antimicrobial metal agent, silver (Ag), has been used as a dopant in taC, with different Ag concentrations on the Ti64 coupons using a hybrid filtered cathodic vacuum arc (FCVA) and magnetron sputtering system. The physiochemical properties of the coated surface were investigated using spectroscopic and electron microscopy techniques. A doping effect of Ag-taC on biofilm formation was investigated and found to have a significant effect on the bacterial-biofilm-forming bacteria Staphylococcus aureus and Pseudomonas aeruginosa depending on the concentration of Ag. Further, the effect of coated and uncoated Ag-taC films on a pathogenic bacterium was examined using SEM. The result revealed that the Ag-taC coatings inhibited the biofilm formation of S. aureus. Therefore, this study demonstrated the possible use of Ag-taC coatings against biofilm-related complications on medical devices and infections from pathogenic bacteria.

Influence of Fe2O3 on synthesis, structure, hardness, and radiation shielding properties of Apatite–Wollastonite (AW) glass ceramics for bone implantation and shielding applications

This paper explores the important impact of Fe2O3 on the synthesis, structure, hardness, and radiation shielding characteristics of Apatite–Wollastonite (AW) glass ceramics for bone implantation and shielding application. The prepared studied samples were prepared and the effects of Fe2O3 addition on the synthesis process, density, and different physical and structural parameters comprehensively investigated. Additionally, the radiation shielding properties were determined by using PHITS simulation code and XCOM calculations for all samples. The results reveal that there is a significant impact of Fe2O3 addition on density, hardness, and radiation shielding of AW glass ceramics. The Vickers hardness values were calculated as 547, 598, and 621 Hv in measurements under 0.1 kg load., the density values are found to be as 2.87, 3.07 and 3.28 g/cm3 for AW, Aw -1Fe, and Aw -2Fe, respectively. The highest linear attenuation coefficient in the AW- 2Fe is 0.096 cm−1, Aw -1Fe showed 0.084 cm−1 and AW gave 0.072 cm−1 at 6 MeV. This study underscores the pivotal role of Fe2O3 as a multifaceted modifier in tailoring the properties of AW glass ceramics for bone implantation and other diverse applications extending from medical imaging to radiation and charged ions shielding.

Fabrication and electrical characterization of carbon coating on a quartz wafer treated with nitrogen ion implantation

This article details the research within the I4Bags project, demonstrating the versatility of low-energy ion implantation protocols as a means to selectively alter the electronic, electrochemical, and electrical properties of thin-film semiconductor batteries. Major goals include increasing gravimetric capacity and improving stability. The current research focuses on the quantitative and qualitative analysis of graphite cathodes, which are then subjected to low-energy ion implantation to transform the solid electrolyte interfacial boundary. The process begins with the formation of carbon coatings by magnetron sputtering on quartz plates, followed by the implantation of nitrogen ions. In this paper, the procedure for obtaining carbon coatings and the application of low energy ion implantation will be presented. These will be verified based on two-dimensional surface resistance maps, which are analyzed in terms of the thickness of the deposited carbon and the changes in electrical structure caused by nitrogen ion implantation.

Poloxamer 407 modified collagen/β-tricalcium phosphate scaffold for localized delivery of alendronate.

Systemic administration of alendronate is associated with various adverse reactions in clinical settings. To mitigate these side effects, poloxamer 407 (P-407) modified with cellulose was chosen to encapsulate alendronate. This drug-loaded system was then incorporated into a collagen/β-tricalcium phosphate (β-TCP) scaffold to create a localized drug delivery system. Nuclear magnetic resonance spectrum and rheological studies revealed hydrogen bonding between P-407 and cellulose as well as a competitive interaction with water that contributed to the delayed release of alendronate (ALN). Analysis of the degradation kinetics of P-407 and release kinetics of ALN indicated zero-order kinetics for the former and Fickian or quasi-Fickian diffusion for the latter. The addition of cellulose, particularly carboxymethyl cellulose (CMC), inhibited the degradation of P-407 and prolonged the release of ALN. The scaffold's structure increased the contact area of P-407 with the PBS buffer, thereby, influencing the release rate of ALN. Finally, biocompatibility testing demonstrated that the drug delivery system exhibited favorable cytocompatibility and hemocompatibility. Collectively, these findings suggest that the drug delivery system holds promise for implantation and bone healing applications.

An Analysis of an ASK Demodulator With Dual Self-Biased Separated Voltages for Implantable Applications

An Analysis of an ASK Demodulator With Dual Self-Biased Separated Voltages for Implantable Applications

Enhanced corrosion resistance and photothermal antibacterial properties of MAO/Fe/GO composite coating on Mg alloy

Fast degradation and postoperative bacterial infection are two main limitations for clinical application of Mg-based implants. Herein, we report a dual functional coating on micro-arc oxidation treated AZ31 Mg alloy (named MAO/Fe/GO) with the integration of graphene oxide (GO) and ferric oxyhydroxide (FeOOH). The photothermal conversion efficiency of MAO/Fe/GO composite coating is as high as 43.2%. Moreover, the MAO/Fe/GO composite coating exhibits enhanced corrosion resistance, antimicrobial activity under 808 nm irradiation, and good biocompatibility.