Electrospun polyvinyl alcohol fibres incorporating an antimicrobial gel for enzymatically controlled reactive oxygen species release

Wounds pose a risk to the skin,our body's primary defence against infections.The rise of antibiotic resistance has prompted the development of novel therapies.RO-101^(■)is an antimicrobial gel that delivers therapeutic levels of hydrogen peroxide(H_(2)O_(2)),a reactive oxygen species,directly to the wound bed.In this study,electrospinning was used to incorporate RO-101^(■)into a polyvinyl alcohol(PVA)sub-micron fibrous mesh that can act as a delivery agent,achieve a sustained release profile,and provide a barrier against infection.Adequate incorporation of this gel into sub-micron fibres was confirmed via nuclear magnetic resonance spectroscopy.Furthermore,scanning electron microscopy exhibited smooth and uniform meshes with diameters in the 200-500 nm range.PVA/RO-101 electrospun meshes generated H_(2)O_(2) in concentrations exceeding 1 m M/(g·m L)(1 m M=1 mmol/L)after 24 h,and the role of sterilisation on H_(2)O_(2) release was evaluated.PVA/RO-101meshes exhibited antimicrobial activity against both Gram-positive Staphylococcus aureus(S.aureus)and Gram-negative Pseudomonas aeruginosa(P.aeruginosa)bacteria,achieving viable count reductions of up to 1 log unit CFU/mm^(2)(CFU:colony-forming units).Moreover,these meshes were capable of disrupting biofilm formation,even against multidrug-resistant organisms such as methicillin-resistant S.aureus(MRSA).Furthermore,increasing the RO-101^(■)concentration resulted in higher H_(2)O_(2) production and an enhanced antimicrobial effect,while fibroblast cell viability and proliferation tests showed a concentration-dependent response with high cytocompatibility at low RO-101^(■)concentrations.This study therefore demonstrates the potential of highly absorbent PVA/RO-101 meshes as potential antimicrobial wound dressings.

Ballistic design and testing of a composite armour reinforced by CNTs suitable for armoured vehicles

This paper is investigating the use of composite armour reinforced by nanomaterials, for the protection of light armoured(LAV) and medium armoured military vehicles(MAV), and the interaction between the composite materials and high-performance ballistic projectiles. Four armour materials, consisted of front hybrid fibre reinforced polymer cover layer, ceramic strike-face, fibre reinforced polymer intermediate layer and the metal matrix composite reinforced backplate, were manufactured and assembled by adhesive technology. The proposed laminated protection system is suitable for armoured ground vehicles;however, it could be used as armour on ground, air and naval platforms. The design of the protection system, including material selection and thickness, was elaborated depending on the performance requirements of Level 4 + STANAG 4569 military standard(projectile 14.5 mm × 114 mm API B32) and especially on a design philosophy which is analysed with the specifications. The backplate of this new composite is a hybrid material of Metal Matrix Composite(MMC) reinforced with carbon nanotubes(CNTs), manufactured with the use of powder metallurgy technique. The composite backplate material was morphologically, mechanically and chemically analysed. Results show that all plates are presenting high mechanical properties and ballistic characteristics, compared to commonly used armour plates. Real military ballistic tests according to AEP-STANAG 4569 were carried out for the total composite armour systems. After the ballistic tests, AA2024-CNT3 showed the best protection results, compared with the other plates(AA2024-CNT1 and AA2024-CNT2), with the projectile being unable to fully penetrate the composite plate.

Customized scaffolds for large bone defects using 3D‑printed modular blocks from 2D‑medical images

Additive manufacturing(AM)has revolutionized the design and manufacturing of patient-specific,three-dimensional(3D),complex porous structures known as scaffolds for tissue engineering applications.The use of advanced image acquisition techniques,image processing,and computer-aided design methods has enabled the precise design and additive manufacturing of anatomically correct and patient-specific implants and scaffolds.However,these sophisticated techniques can be timeconsuming,labor-intensive,and expensive.Moreover,the necessary imaging and manufacturing equipment may not be readily available when urgent treatment is needed for trauma patients.In this study,a novel design and AM methods are proposed for the development of modular and customizable scaffold blocks that can be adapted to fit the bone defect area of a patient.These modular scaffold blocks can be combined to quickly form any patient-specific scaffold directly from two-dimensional(2D)medical images when the surgeon lacks access to a 3D printer or cannot wait for lengthy 3D imaging,modeling,and 3D printing during surgery.The proposed method begins with developing a bone surface-modeling algorithm that reconstructs a model of the patient’s bone from 2D medical image measurements without the need for expensive 3D medical imaging or segmentation.This algorithm can generate both patient-specific and average bone models.Additionally,a biomimetic continuous path planning method is developed for the additive manufacturing of scaffolds,allowing porous scaffold blocks with the desired biomechanical properties to be manufactured directly from 2D data or images.The algorithms are implemented,and the designed scaffold blocks are 3D printed using an extrusion-based AM process.Guidelines and instructions are also provided to assist surgeons in assembling scaffold blocks for the self-repair of patient-specific large bone defects.