Fabrication of surface modified antibacterial Ti6Al4V alloy powder reinforced gelatin/chitosan composite scaffold for tissue engineering applications

The present work attempted to modify Ti6Al4V (Ti64) alloy powder to induce biocompatibility and antimicrobial properties by incorporating Ca²⁺ and Ag⁺ ions, respectively using a simple chemical treatment followed by ion exchange method. Thus functionally modified Ti64 alloy powders characterized using FE-SEM and Raman spectroscopic techniques indicate the formation of fine porous network structure along with the evolution of different phases of titania upon heat treatment in presence of Ca²⁺ and Ag⁺ ions. The incorporation of Ca²⁺ ions and transformation of Ag⁺ ions into AgNPs and their decoration on the nano porous network structure have been confirmed by the HR-TEM and EDX results. Optimized concentration of AgNPs decorated Ti64 alloy powder not only found to induce antimicrobial activity against both Gram-positive S. aureus and Gram-negative E. coli bacteria and also compatible with MG-63 cell lines. Surface functionalized Ti64 alloy powder was subsequently used as reinforcement for the fabrication of gelatin - chitosan composite scaffolds using the lyophilization technique. Thus fabricated composite scaffold was analyzed for its pore morphology and pore distribution along with its in-vitro cell toxicity towards MG-63 cell lines using MTT assay. Taken together, surface modified Ti64 alloy powder reinforced gelatin-chitosan composite scaffold with biocompatible and antimicrobial properties is expected to be suitable for tissue engineering applications.     

Engineering Materials for Neurotechnology

Neurotechnology applies methods and devices to mitigate the burden of neurological and mental disorders. In particular, neural interfaces establish a long-term, seamless, symbiotic integration between implants and neural tissue. Materials play a pivotal role in neurotechnology. Advanced materials and materials engineering are crucial to achieving the desired function and outcome. Recently, neural interfaces extended their range of applications with the emergence of flexible, conformable, stretchable, injectable, and transient electronics. However, despite this enormous advancement in materials science and engineering, clinical devices still rely on old-fashioned but reliable materials and processes. The gap between research development and industry adoption has recently gained high interest. This article analyzes recent developments, discusses roadblocks, and provides a roadmap for materials engineering applied to neurotechnology.     

Rational Design and Synthesis of Lignin-Derived Smart Sunscreens

Lignin exhibits a long-active UV-blocking property due to its macromolecular aromatic structure and unique semiquione-quione-hydroquione transition. However, its poor absorbance in UVA region (320–400 nm) and irregular aggregation are still the obstacles. Herein, active spirapyrane (SP-Br) is synthesized and covalently introduced into alkali lignin (AL) to construct photo-stimulated UV-absorbing enhancement sunscreen actives (AL-SP_n). The introduction of SP significantly improved the absorbance of AL in UVA region and its aggregation is effectively eased. When the optimal AL-SP₃ solution is exposed to UV irradiation, the color turned purple, and the absorbance in UVA region further improved as the unconjugated SP transformed into conjugated merocyanine (MC) structure. When the light is removed, the solution recovered light yellow. The antioxidant property of AL endow the reversible SP-MC transformation with good cyclic stability. As-prepared AL-SP₃ based sunscreen exhibit obvious photo-stimulated enhancement effect. The sun protection factor (SPF) improved from 23 to 89 after 4 h irradiation, and can maintain the high performance for another 8 h. In addition, it exhibit low permeation and good biocompatibily in vitro and vivo, demonstrating its good potential in practical use.     

Long-Term Stability,Biocompatibility, and Magnetization of Suspensions of Isolated Bacterial Magnetosomes

Magnetosomes are magnetic nanoparticles biosynthesized by magnetotactic bacteria. Due to a genetically strictly controlled biomineralization process, the ensuing magnetosomes have been envisioned as agents for biomedical and clinical applications. In the present work, different stability parameters of magnetosomes isolated from Magnetospirillum gryphiswaldense upon storage in suspension (HEPES buffer, 4 °C, nitrogen atmosphere) for one year in the absence of antibiotics are examined. The magnetic potency, measured by the saturation magnetization of the particle suspension, drops to one-third of its starting value within this year—about ten times slower than at ambient air and room temperature. The particle size distribution, the integrity of the surrounding magnetosome membrane, the colloidal stability, and the biocompatibility turn out to be not severely affected by long-term storage.     

Tough,Bio-disintegrable and Stretchable Substrate Reinforced with Nanofibers for Transient Wearable Electronics

Research on transient wearable electronics with stretchable components is of increasing interest because of their abilities to conform seamlessly to human tissues and, more interestingly, disappear from the environment when disposed. To wear them comfortably, their component materials must be pliable, tough, stretchable, biocompatible, and disintegrable. However, most biodegradable materials are not stretchable or tough, limiting their use in transient wearable electronics. Herein, these challenges are addressed by demonstrating a biodegradable nanofiber (NF)-reinforced water-borne polyurethane (NFR-WPU) with stretchability, toughness, and partial biodegradability by embedding biodegradable composite NFs of poly(glycerol sebacate): poly(vinyl alcohol) (PGS:PVA) into the WPU matrix, thus rendering its properties tunable. An optimal loading amount of NFs into the NFR-WPU significantly enhanced the toughness by 19 times while maintaining the Young's modulus as low as 3.3 MPa. Furthermore, the NFR-WPU substrate has very high fracture toughness and shows excellent biocompatibility. Moreover, the NFR-WPU has a disintegration rate nine times greater than that of pristine WPU. Finally, disintegrable and stretchable triboelectric and capacitive touch sensors on the NFR-WPU are fabricated and demonstrated for potential use in transient wearable electronics.