Three-dimensional bioprinting of cell-laden hydrogels in a sacrificial support-bath has recently emerged as a potential solution for fabricating complex biological structures. Physical properties of the support-bath strongly influence the bioprinting process and the outcome of the fabricated constructs. In this study, we reported the application of a composite Pluronic-nanoclay support-bath including calcium ions as the crosslinking agent for bioprinting of cell-laden alginate-based hydrogels. By tuning the rheological properties, a shear-thinning composite support-bath with fast self-recovery behavior was yielded, which allowed continuous printing of complex and large-scale structures. The printed structures were easily and efficiently harvested from the support-bath without disturbing their shape fidelity. Moreover, the results showed that support-bath assisted bioprinting process did not influence the viability of cells encapsulated within hydrogel. This study demonstrates that Pluronic-nanoclay support-bath can be utilized for bioprinting of complex, cell-laden constructs for vascular and other tissue engineering applications.

Melt electrospinning writing has been emerged as a promising technique in the field of tissue engineering, with the capability of fabricating controllable and highly ordered complex three-dimensional geometries from a wide range of polymers. This three-dimensional (3D) printing method can be used to fabricate scaffolds biomimicking extracellular matrix of replaced tissue with the required mechanical properties. However, controlled and homogeneous cell attachment on melt electrospun fibers is a challenge. The combination of melt electrospinning writing with other tissue engineering approaches, called hybrid biomanufacturing, has introduced new perspectives and increased its potential applications in tissue engineering. In this review, principles and key parameters, challenges, and opportunities of melt electrospinning writing, and particularly, recent approaches and materials in this field are introduced. Subsequently, hybrid biomanufacturing strategies are presented for improved biological and mechanical properties of the manufactured porous structures. An overview of the possible hybrid setups and applications, future perspective of hybrid processes, guidelines, and opportunities in different areas of tissue/organ engineering are also highlighted.

Application of cold atmospheric-pressure plasma (CAP) for wound treatment and decontamination of food or water often includes the presence of proteins. These proteins contain amino acids with functional groups, such as thiol (SH) groups. Plasma-mediated effects in biological systems involve reactive oxygen and nitrogen species. In this regard, redox signaling is often mediated via thiol groups. The aim of this study was to investigate the influence of a protein and an SH group containing amino acids on the antimicrobial properties of plasmatreated saline solution (0.85% NaCl, w/v) and on the direct CAP efficacy on solid wet agar plates. Plasma treatment of saline solution was realized using an ACdriven pin-to-liquid discharge. After plasma treatment for 10 minutes, the amino acids L-cysteine (contains SH group) or L-alanine (no SH group) or bovine serum albumin (BSA; with approximately 6% cysteine content) were added together with the test microorganism Escherichia coli K-12 (DSM 11250/ NCTC 10538) for an exposure time of up to 60 min. The total viable cell count was determined at appropriate time intervals. A concentration-dependent repeal of the antimicrobial efficacy was determined. Therefore, 0.0025% of BSA did not have any influence, whereas 0.25% of BSA w/v, as well as the tested amino acids, did not result in the inactivation of E. coli. The difference between L-alanine and L-cysteine was negligible, suggesting only a minor effect of the presence of SH groups. Dimerization of L-cysteine was shown by LC/MS analyses, whereas no derivatization of L-alanine was detected. To test the influence of proteins in direct plasma treatment on wet surfaces, E. coli was plated together with BSA on soybean-casein digest agar surface. Another setup was based on agar plates, which contained different concentrations of peptone (a mixture of peptides and amino acids). The agar plates were regularly treated by the argon-driven CAP jet kINPen Med (neoplas tools GmbH, Greifswald, Germany). After overnight incubation, inhibition zones were analyzed. The bacterial growth was independent of protein or peptone content for this direct plasma treatment. Summarizing all, the antibacterial effect of the Plasma Process Polym. 2019;16:e1800164 www.plasma-polymers.com

Surgical site infections have a remarkable impact on morbidity, extended hospitalization and mortality. Sutures strongly contribute to development of surgical site infections as they are considered foreign material in the human body. Sutures serve as excellent surfaces for microbial adherence and subsequent colonization, biofilm formation and infection on the site of a surgery. Various antimicrobial sutures have been developed to prevent suture-mediated surgical site infection. However, depending on the site of surgery, antimicrobial sutures may remain ineffective, and antimicrobial agents on them might have drawbacks. Plasma, defined as the fourth state of matter, composed of ionized gas, reactive oxygen and nitrogen species, free radical and neutrals, draws attention for the control and prevention of hospital-acquired infections due to its excellent antimicrobial activities. In the present study, the efficacy of non-thermal atmospheric plasma treatment for prevention of surgical site infections was investigated. First, contaminated poly (glycolic-co-lactic acid), polyglycolic acid, polydioxanone and poly (glycolic acid-co-caprolactone) sutures were treated with non-thermal atmospheric plasma to eradicate contaminating bacteria like Staphylococcus aureus and Escherichia coli. Moreover, sutures were pre-treated with non-thermal atmospheric plasma and then exposed to S. aureus and E. coli. Our results revealed that non-thermal atmospheric plasma treatment effectively eradicates contaminating bacteria on sutures, and non-thermal atmospheric plasma pre-treatment effectively prevents bacterial colonization on sutures without altering their mechanical properties. Chemical characterization of sutures was performed with FT-IR and XPS and results showed that non-thermal atmospheric plasma treatment substantially increased the hydrophilicity of sutures which might be the primary mechanism for the prevention of bacterial colonization. In conclusion, plasma-treated sutures could be considered as novel alternative materials for the control and prevention of surgical site infections.

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Recent studies on three-dimensional (3D) bioprinting of cell-laden gelatin methacryloyl (GelMA) hydrogels have provided promising outcomes for tissue engineering applications. However, the reliance on the use of photo-induced gelation processes for the bioprinting of GelMA and the lack of an alternative crosslinking process remain major challenges for the fabrication of cell-laden structures. Here, we present a novel crosslinking approach to form cell-laden GelMA hydrogel constructs through 3D embedded bioprinting without using any external irradiation that could drastically affect cell viability and functionality. This approach consists of a one-step type of crosslinking via bisulfite-initiated radical polymerization, which is combined with embedded bioprinting technology to improve the structural complexity of printed structures. By this means, complex-shaped hydrogel bio-structures with cell viability higher than 90 % were successfully printed within a support bath including sodium bisulfite. This study offers an important alternative to other photo-induced gelation processes to improve the bio-fabrication of GelMA hydrogel with high cell viability.

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Soft tissue injuries such as volumetric muscle loss (VML) are often too large to heal normally on their own, resulting in scar formation and functional deficits. Decellularized extracellular matrix (dECM) scaffolds placed into these wounds have shown the ability to modulate the immune response and drive constructive healing. This provides a potential solution for functional tissue regeneration, however, these acellular dECM scaffolds are challenging to fabricate into complex geometries. 3D bioprinting is uniquely positioned to address this, being able to create patient-specific scaffolds based on clinical 3D imaging data. Here, a process to use freeform reversible embedding of suspended hydrogels (FRESH) 3D bioprinting and computed tomography (CT) imaging to build large volume, patient-specific dECM patches (≈12 × 8 × 2 cm) for implantation into canine VML wound models is developed. Quantitative analysis shows that these dECM patches are dimensionally accurate and conformally adapt to the surface of complex wounds. Finally, this approach is extended to a human VML injury to demonstrate the fabrication of clinically relevant dECM scaffolds with precise control over fiber alignment and micro-architecture. Together these advancements represent a step towards an improved, clinically translatable, patient-specific treatment for soft tissue defects from trauma, tumor resection, and other surgical procedures.