In vivo feasibility test using transparent carbon nanotube-coated polydimethylsiloxane sheet at brain tissue and sciatic nerve

Nanoparticle-based nanocomposite coatings with postprocessing for enhanced antimicrobial capacity of polymeric film

Bacterial adhesion and biofilm formation on surfaces pose a significant risk of microbial contamination and chronic diseases, leading to potential health complications. To mitigate this concern, the implementation of antibacterial coatings becomes paramount in reducing pathogen propagation on contaminated surfaces. To address this requirement, our study focuses on developing cost-effective and sustainable methods using polymer composite coatings. Copper and titanium dioxide nanoparticles were used to assess their active antimicrobial functions. After coating the surface with nanoparticles, four different combinations of two postprocessing treatments were performed. Intense pulsed light was utilized to sinter the coatings further, and plasma etching was applied to manipulate the physical properties of the nanocomposite-coated sheet surface. Bacterial viability was comparatively analyzed at four different time points (0, 30, 60, and 120 min) upon contact with the nanocomposite coatings. The samples with nanoparticle coatings and postprocessing treatments showed an above-average 84.82% mortality rate at 30 min and an average of 89.77% mortality rate at 120 min of contact. In contrast, the control sample, without nanoparticle coatings and postprocessing treatments, showed a 95% microbe viability after 120 min of contact. Through this study, we gained critical insights into effective strategies for preventing the spread of microorganisms on high-touch surfaces, thereby contributing to the advancement of sustainable antimicrobial coatings.

Regenerative rehabilitation with conductive biomaterials for spinal cord injury

The individual approaches of regenerative medicine efforts alone and rehabilitation efforts alone have not yet fully restored function after severe spinal cord injury (SCI). Regenerative rehabilitation may be leveraged to promote regeneration of the spinal cord tissue, and promote reorganization of the regenerated neural pathways and intact spinal circuits for better functional recovery for SCI. Conductive biomaterials may be a linchpin that empowers the synergy between regenerative medicine and rehabilitation approaches, as electrical stimulation applied to the spinal cord could facilitate neural reorganization. In this review, we discuss current regenerative medicine approaches in clinical trials and the rehabilitation, or neuromodulation, approaches for SCI, along with their respective translational limitations. Furthermore, we review the translational potential, in a surgical context, of conductive biomaterials (e.g., conductive polymers, carbon-based materials, metallic nanoparticle-based materials) as they pertain to SCI. While pre-formed scaffolds may be difficult to translate to human contusion SCIs, injectable composites that contain blended conductive components and can form within the injury may be more translational. However, given that there are currently no in vivo SCI studies that evaluated conductive materials combined with rehabilitation approaches, we discuss several limitations of conductive biomaterials, including demonstrating safety and efficacy, that will need to be addressed in the future for conductive biomaterials to become SCI therapeutics. Even so, the use of conductive biomaterials creates a synergistic opportunity to merge the fields of regenerative medicine and rehabilitation and redefine what regenerative rehabilitation means for the spinal cord. STATEMENT OF SIGNIFICANCE: For spinal cord injury (SCI), the individual approaches of regenerative medicine and rehabilitation are insufficient to fully restore functional recovery; however, the goal of regenerative rehabilitation is to combine these two disparate fields to maximize the functional outcomes. Concepts similar to regenerative rehabilitation for SCI have been discussed in several reviews, but for the first time, this review considers how conductive biomaterials may synergize the two approaches. We cover current regenerative medicine and rehabilitation approaches for SCI, and the translational advantages and disadvantages, in a surgical context, of conductive biomaterials used in biomedical applications that may be additionally applied to SCI. Furthermore, we identify the current limitations and translational challenges for conductive biomaterials before they may become therapeutics for SCI.

A printing-spray-transfer process for attaching biocompatible and antibacterial coatings to the surfaces of patient-specific silicone stents

An antibacterial coating with stable antibacterial properties and favorable biocompatibility is recognized as an effective method to prevent bacterial adhesion and biofilm formation on biomedical implant surfaces. In this study, a convenient and low-cost printing-spray-transfer process was proposed that enables reliably attaching antibacterial and biocompatible coatings to patient-specific silicone implant surfaces. A desktop three-dimensional printer was used to print the mold of silicone implant molds according to the characteristics of the diseased areas. Multiwalled carbon nanotubes (MWCNTs) uniformly decorated with silver nanoparticles (AgNPs/CNTs) were synthesized as the antibacterial materials for the spray process. The well-distributed AgNPs/CNT coating was anchored to the silicone surface through an in-mold transfer printing process. Stable adhesion of the coatings was assessed via tape testing and UV-vis spectra. Hardly any AgNPs/CNTs peeled off the substrate, and the adhesion was rated at 4B. Antibacterial activity, Ag release, cell viability and morphology were further assessed, revealing high antibacterial activity and great biocompatibility. The process proposed herein has potential applications for fabricating stable antibacterial coatings on silicone implant surfaces, especially for patient-specific silicone implants such as silicone tracheal stents.

Modification of tubular chitosan-based peripheral nerve implants: applications for simple or more complex approaches

Surgical treatment of peripheral nerve injuries is still a major challenge in human clinic. Up to now, none of the well-developed microsurgical treatment options is able to guarantee a complete restoration of nerve function. This restriction is also effective for novel clinically approved artificial nerve guides. In this review, we compare surgical repair techniques primarily for digital nerve injuries reported with relatively high prevalence to be valuable attempts in clinical digital nerve repair and point out their advantages and shortcomings. We furthermore discuss the use of artificial nerve grafts with a focus on chitosan-based nerve guides, for which our own studies contributed to their approval for clinical use. In the second part of this review, very recent future perspectives for the enhancement of tubular (commonly hollow) nerve guides are discussed in terms of their clinical translatability and ability to form three-dimensional constructs that biomimick the natural nerve structure. This includes materials that have already shown their beneficial potential in in vivo studies like fibrous intraluminal guidance structures, hydrogels, growth factors, and approaches of cell transplantation. Additionally, we highlight upcoming future perspectives comprising co-application of stem cell secretome. From our overview, we conclude that already simple attempts are highly effective to increase the regeneration supporting properties of nerve guides in experimental studies. But for bringing nerve repair with bioartificial nerve grafts to the next level, e.g. repair of defects > 3 cm in human patients, more complex intraluminal guidance structures such as innovatively manufactured hydrogels and likely supplementation of stem cells or their secretome for therapeutic purposes may represent promising future perspectives.

3D scaffolds for brain tissue regeneration: architectural challenges

Critical analysis of experimental studies on 3D scaffolds for brain tissue engineering.