Nature-inspired surface modification strategies for implantable devices

Medical and implantable devices are essential instruments in contemporary healthcare, improving patient quality of life and meeting diverse clinical requirements. However, ongoing problems such as bacterial colonization, biofilm development, foreign body responses, and insufficient device-tissue adhesion hinder the long-term effectiveness and stability of these devices. Traditional methods to alleviate these issues frequently prove inadequate, necessitating the investigation of nature-inspired alternatives. Biomimetic surfaces, inspired by the chemical and physical principles found in biological systems, present potential opportunities to address these challenges. Recent breakthroughs in manufacturing techniques, including lithography, vapor deposition, self-assembly, and three-dimensional printing, now permit precise control of surface properties at the micro- and nanoscale. Biomimetic coatings can diminish inflammation, prevent bacterial adherence, and enhance stable tissue integration by replicating the antifouling, antibacterial, and adhesive properties observed in creatures such as geckos, mussels, and biological membranes. This review emphasizes the cutting-edge advancements in biomimetic surfaces for medical and implantable devices, outlining their design methodologies, functional results, and prospective clinical applications. Biomimetic coatings, by integrating biological inspiration with advanced surface engineering, have the potential to revolutionize implantable medical devices, providing safer, more lasting, and more effective interfaces for prolonged patient benefit.

Construction of Photoinitiator Functionalized Spherical Nanoparticles Enabling Favorable Photoinitiating Activity and Migration Resistance for 3D Printing

A straight-forward method was exploited to construct a multifunctional hybrid photoinitiator by supporting 2-hydroxy-2-methylpropiophenone (HMPP) onto a nano-silica surface through a chemical reaction between silica and HMPP by using (3-isocyanatopropyl)-triethoxysilane (IPTS) as a bridge, and this was noted as silica-s-HMPP. The novel hybrid-photoinitiator can not only initiate the photopolymerization but also prominently improve the dispersion of nanoparticles in the polyurethane acrylate matrix and enhance the filler-elastomer interfacial interaction, which results in excellent mechanical properties of UV-cured nanocomposites. Furthermore, the amount of extractable residual photoinitiators in the UV-cured system of silica-s-HPMM shows a significant decrease compared with the original HPMM system. Since endowing the silica nanoparticle with photo-initiated performance and fairly lower mobility, it may lead to a reduction in environmental contamination compared to traditional photoinitators. In addition, the hybrid-photoinitiator gives rise to an accurate resolution object with a complex construction and favorable surface morphology, indicating that multifunctional nanosilica particles can be applied in stereolithographic 3D printing.

Biomimetic Porous Nanofiber-Based Oil Pump for Spontaneous Oil Directional Transport and Collection

Directional transport and manipulation of liquid substances have drawn wide attention owing to their crucial applications from microfluid to large-area water harvesting. Spontaneous oil directional transport, especially having the prospect of large-scale manufacturing, plays a huge role in marine oil cleanup, but is exposed to the limitations such as low efficiency and transport velocity. Here, we report a biomimetic porous nanofiber-based oil pump from cosolvent electrospinning, endowed with the parenchyma cellular structure of plants. These tightly packed and uniform nanoporous structures of nanofibers are capable of self-pumping oil upward with an ultrahigh pumping rate of 21.12 g g^-1 h^-1, which has been proposed as an explicit mechanism. Following oil directional transport, it can obtain an efficient oil collection of 127.52 g g^-1. We anticipate that our designed oil pump will provide a versatile platform for spontaneous oil directional transport and collection with potential applications in the fields of laboratory-on-a-chip, microreaction devices, chemical engineering, and the petrochemical industry.

Preparation of Electrosprayed, Microporous Particle Filled Layers

Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer known for its excellent hydrophobic properties. In this work, samples from PTFE dispersions with different combinations of water and carbon microparticles were prepared using an electrospraying method. The morphologies and sizes of carbon particles were investigated and the properties of layers including roughness, hydrophobicity and electrical resistivity were investigated. The non-conductive carbon microparticles were selected as a model particle to check the compatibility and electrospraying ability, and it had no effect on the hydrophobic and electrical properties. Carbon microparticles in polymer solution increased the degree of ionization and was found to be beneficial for the shape control of materials. The results showed that PTFE dispersion with the composition of water and carbon microparticles produced fine sphere particles and the layer fabricated with increased roughness. It was also found that the electrical resistivity and hydrophobicity of all the layers comparatively increased. The fabricated microporous layers can be used in various applications like interlining layer in multilayer textile sandwiches.

Preparation of fluorinated PCL porous microspheres and a super-hydrophobic coating on fabrics via electrospraying

In this study, fluorinated polycaprolactone (PCL) block polymers with different fluorine contents were synthesized via atom transfer radical polymerization (ATRP). An electrospraying technique was used to prepare fluorinated PCL microspheres with different microstructures. In contrast to the golf ball shape of unmodified PCL microspheres displaying porous pits on the surface, block polymer PCL-PTFOA(2 h) and PCL-PTFOA(6 h) microsphere surfaces displayed regular honeycomb-like pore structures. Thermally induced and evaporation-induced phase separations are proposed as the main mechanisms involved in the formation of the porous microstructures. The micro-phase separation between the two blocks of the fluorinated PCL copolymer is another factor that promoted the uniform collapse on the microsphere surface and the formation of its rugged wall. The surface roughness of the porous microspheres significantly improved their hydrophobicity, generating coating contact angles on aluminium foil substrates that measured as high as 162.4 ± 1.5°, which revealed that the surfaces were super-hydrophobic. Lastly, cotton fabric was directly coated with the fluorinated polymer microspheres via electrospraying, resulting in super-hydrophobic surfaces and CAs reaching 160.0 ± 1.3°. The results demonstrate that electrospraying is a simple, innovative and cost-effective method for preparing polymer microspheres with controllable microstructures for fabric coating applications.

Effect of electrospinning process variables on the size of polymer fibers and bead-on-string structures established with a 23 factorial design

This work examines the effect of selected process parameters on the diameter of uniform and heterogeneous fibers (with and without bead-on-string structures) and the size of beads obtained during the electrospinning process. A 2³ factorial design was performed to determine the influence of the following factors: electrical voltage, flow rate and dynamic viscosity of the poly(vinylpyrrolidone) ethanolic solution. Factorial design enables the analysis of the mathematical relationship between the chosen factors and the response with a minimum number of experiments. The factor having the most significant impact on the size of beaded fibers and beads was the solution viscosity, while the voltage had the greatest influence on the bead-free fiber diameter. The interactions between the studied factors were also analyzed. It was found that the presented method can be used for the design of an optimal and cost-effective electrospinning process, allowing the desired product to be obtained with expected features.

Facile synthesis of branched polyvinyl acetate via redox-initiated radical polymerization

Although branched polymers find widespread applications, the rational design and synthesis of branched vinyl polymers via the conventional radical (co)polymerization of commercially available monomers is still a challenge for researchers in this field.