29. Jahrestagung der Deutschen Gesellschaft für Biomaterialien

Chair

Prof. Dr.

Prof. Dr. Dr.

Electrospun nonwoven materials as local drug-delivery systems

Tissue regeneration/regenerated medicine

Additive manufacturing (e. g. 3D printing)

Abstract text (incl. figure legends and references) Introduction Like almost all markets in the healthcare, the market for drug delivery systems (DDS) is also benefiting from the fact that humanity is growing constantly and is also becoming older. The fields of application for DDS made of electrospun nonwoven materials are primarily in the field of wound dressings containing active substances for the treatment of microbial infections. The treatment of such infections with local DDS plays an important role, especially in the oral, maxillofacial and bone area. Objectives Our aim was to achieve DDS for local periodontitis treatment based on electrospun fusidic acid (FSN)-loaded resorbable polyester fibers. Material &amp; methods The electrospun fibers were based on biodegradable RESOMER® polymers (polylactide, polydioxanone, polycaprolactone) from Evonik. They were loaded with 10-20 % (w/w) FSN and characterized in terms of fiber diameter/morphology (light microscopy/SEM), stability/elasticity (tensile test), degradation behavior, cytocompatibility (live/dead assay and XTT test) as well as drug release profile (UV/VIS spectroscopy). Antibacterial activity was tested using an agar diffusion test on the following bacterial species: Porphyromonas gingivalis, Staphylococcus aureus and Streptococcus sobrinus. Results The observed release behavior varied widely depending on the polymer used. The polylactide-based electrospun fiber fleece loaded with FSN showed continuous release for at least 28 days. Within this period, corresponding inhibition zones (agar diffusion test) were formed in Porphyromonas gingivalis and Staphylococcus aureus. The growth of Staphylococcus aureus was completely inhibited. Conclusion This study shows that FSN-loaded electrospun fiber nonwoven materials represent an interesting class of resorbable drug delivery systems. Sustained drug release properties and cytocompatibility suggest their potential clinical applicability for the treatment of periodontal diseases.

Short Talk

Development of anti-platelet adhesion/activation surfaces

Surface modification technologies

Cell-material interactions

Abstract text (incl. figure legends and references) Platelets tend to be activated immediately when contacting any non-physiological surfaces. The development of anti-platelet adhesion/activation surfaces is important for platelet storage bags/tubing and many blood-contacting devices. Chemical modification can tune the response of cells to contacting surfaces but requires a long process involving many regulatory challenges to transfer into a marketable product. Biophysical modification refers to varying surface topography, elasticity, or porosity, and thus, can overcome those limitations. We developed hydrogels and nanostructured surfaces of different shapes to minimize platelet adhesion/activation. Further, we integrated functional molecules into these surfaces to enhance the surface function. The glass was modified with biomaterials including collagen, laminin, agarose, fibronectin, and poly-L-lysine (Fig. 1A)1,2 while nanostructured surfaces (Fig. 1B)3-5 were fabricated using a mask-free nanoprinting fluid force microscope. Atomic force microscopy, contact angle, confocal laser microscopy, and scanning electron microscopy were used to characterize the surfaces including stiffness, wettability, platelet-surface adhesion force, nanostructures, and platelet-surface response. Agarose was identified as the most stable surface and exhibited the strongest anti-platelet adhesion properties.2 Interestingly, integration into agarose iron oxide nanoparticles that carry antibacterial characteristics did not enhance platelet activation2 but caused bacterial death. Groove, hive, and grid nanostructured surfaces exhibited strong anti-platelet adhesion properties, especially the hive features.3,4 After UV-cure, the integrated biomolecules (rhodamine or biotin) in the nanostructures conserved their functions.5 Our findings contribute to the development of better anti-platelet adhesion/activation and anti-bacterial surfaces for blood-contacting devices.

Plasma-activated water as decontamination agent for healthcare textiles

Infections

Clinical applications and translation

Abstract text (incl. figure legends and references) Introduction Plasma-activated water (PAW) is produced by treating water with plasma and is being tested as a chemical agent for the decontamination of food, surfaces and medical equipment due to its good antimicrobial properties. However, there is no research on whether textiles can be decontaminated with PAW, whereby pathogens present on healthcare textiles can contribute to the spread of hospital-acquired infections and therefore pose a serious threat in hospitals and medical facilities. Objective The objective of this study was to investigate whether PAW can be used as an alternative method for decontamination of healthcare textiles. Materials and Methods An Openair® plasma system (Plasmatreat GmbH, Steinhagen, Germany) was used to produce PAW by treating distilled water, and a 100 % cotton lab coat was chosen as healthcare textile. Optimal treatment parameters such as time of PAW exposure and stirring rate were determined and the decontamination efficiency of PAW against Escherichia coli and Staphylococcus aureus was investigated. Furthermore, the effect of repeated PAW cycles on the mechanical and chemical properties of the textiles was evaluated. Results PAW with a pH of 2.38 ± 0.40 was produced. The decontamination efficiency was dependent on the time the textiles were exposed to PAW and the stirring rate. For Escherichia coli, a complete reduction was achieved after 15 min of treatment at 250 rpm, while for Staphylococcus aureus 15 min at 500 rpm were needed. To ensure adequate bacterial reduction on the textiles, at least 15 min of PAW treatment and a PAW agitation of 500 rpm were set as the optimal process parameters. No effects of the PAW treatment on the mechanical and chemical properties of the textiles could be detected after up to 15 cycles. Conclusion PAW could be a promising approach to gently decontaminate healthcare textiles and reduce the spread of pathogens.

Printed biosensors for the cost-effective and comprehensive detection of Interleukin-6 as an early stage sepsis marker

Abstract text (incl. figure legends and references) Sepsis due to acute inflammation is a serious health risk for patients. According to the WHO, one in five deaths worldwide can be linked to a severe course of sepsis. Especially after operations, the state of health must be critically monitored. Due to the high mortality rate of sepsis, which increases approx. 8 % per hour, close patient monitoring must be carried out to enable rapid therapy. However, current laboratory methods make this difficult due to costs, the need for trained personnel and, above all, the time required for analysis. Biosensors as point-of-care devices offer a simple solution for cost-effective and rapid monitoring. In this work, two different biosensor types for the detection of Interleukin-6 (IL-6) as early stage Sepsis marker are investigated and compared. First, a colorimetric biosensor produced with inkjet printing was developed. Antibody and aptamer linked gold-nanoparticles were applied as bioreceptors. In presence of IL-6 the nanoparticles aggregate, which leads to a shifting of the plasmon resonance peak and an associated color change from red to blue. This allows nurses and caregivers to assess the state of health within a few minutes without technical aids or special training. Second, a screen-printed electrochemical biosensor that enables a quantitative determination of IL-6 levels was developed. Here, the first tests already showed a sensitivity of 56 % in a very wide measuring range from 0 to 1600 pg. Improvements in the manufacturing process can be expected to improve these values. In sum, two approaches for detecting IL-6 and thus sepsis at an early stage are presented and discussed. Not only the biosensors themselves are presented, but also their potential for scaling up through (bio)printing technologies. In this way, we would like to draw attention to the high potential of this manufacturing technology for this type of sensor and future applications in cost-effective and comprehensive point-of-care monitoring of analytes.

PD Dr.

Bacteria capturing alumina textiles for wound dressing applications

Abstract text (incl. figure legends and references) Introduction: Ceramic textiles are used in high-temperature applications1 and may be suitable as wound dressing like previously reported anodic aluminium oxide (AAO).2 Objective: Here, we investigate tricot knit alumina ceramic textiles (Zircar Ceramics Inc., USA) as a flexible wound dressing that may shield the wound surface from external bacterial infection and capture bacteria already present in the wound. Materials and Methods: E. coli and B. subtilis were incubated with alumina textiles and commercial dressings non-woven mesh (Cutimed® Sorbact®), a woven gauze (LEINA-WERKE) and a non-woven gauze (LEINA-WERKE) on agar plates to explore bacteria permeation (Fig. 1A) and attachment (Fig. 1B). After textile removal from the agar, visual analysis of agar plates and optical density measurements (595 nm) of the collected bacteria from the agar surface were performed. In addition, artificial wound bed tests with preformed biofilms were conducted (Fig 1C). Results: After incubation with alumina textiles, negligible bacteria permeation was observed in the set up Fig.1A and most bacteria were captured from agar surface by textiles using set up in Fig 1B. SEM studies showed both types of bacteria attached to alumina textiles.They outperformed commercial dressings in capturing bacteria from agar surfaces and also in preventing bacteria permeation into agar surface.The results of the artificial wound bed tests show that the alumina textiles retained their bacteria capturing ability in this complex biological environment. Conclusion: Due to their flexible and bioinert nature, alumina textiles show great potential as bacteria-capturing wound dressings which can be extended to different bacteria strains in the future. Figure 1: (A, B) Design of the bacterial interaction study; (C) artificial wound bed tests with bacteria and alumina textiles References [1] D. B Marshall et al; Annu. Rev. Mater. Res.,2008.[2] D.Dutta et al; ACS Appl. Bio Materials,2021.

Professor

In vitro response of monocytes to PHMB-coated Ti6Al4V alloy implant material

Antimicrobial coatings

Abstract text (incl. figure legends and references) Introduction: Periprosthetic joint infections are a devastating complication after arthroplasty, leading to rejection of the prosthesis. Septic loosening may be prevented by coating of the implant surface with an antimicrobial active agent as Poly(hexamethylene) biguanide (PBMH) a microbiocidal substance with low cytotoxicity and a long-lasting microbicidal effect. Objectives: To preclude aseptic loosening by excessive activation of the immune system, possible inflammatory effects on monocytes upon contact with PHMB-coated surfaces were analyzed. Materials &amp; methods: Monocytes were isolated from human buffy coat and incubated on PHMB-coated Ti6Al4V alloy for up to 7 days. Next to analysis of cell adherence, actin filaments were stained for identifying effects on the cytoskeleton and cytokine secretion was quantified. Afterwards, monocytes were co-cultured with SaOs-2 osteoblasts to identify effects on osteoneogenesis. For that, cell viability, generation of alkaline phosphatase and mineralization were quantified. Results: In comparison to the control (non-coated material), monocytes on PHMB-coated material were not spreading on the specimen&quot;s surface. On PHMB-coated surfaces, monocytes secreted higher amounts of inflammatory cytokines. In co-culture, viability of SaOs-2 osteoblasts on PHMB-coated material is as high as on non-coated surfaces. There was no effect on the generation of alkaline phosphatase but mineralization was reduced. Conclusion: The surface treatment with PHMB led to an activation of monocytes to secrete inflammatory different cytokines. In co-culture, this cytokine secretion had no effect on SaOs-2 cell viability and alkaline phosphatase but it had effects on mineralization that has to be analyzed in more detail and long-term studies to preclude effects on osteoneogenesis.

In vivo application of calcium phosphate nanoparticles carrying anti-p65 NF-ĸB siRNA to treat murine colon inflammation

Abstract text (incl. figure legends and references) Introduction Ulcerative colitis (UC) is a type of inflammatory bowel disease that affects the colon and rectum. UC causes abdominal pain, diarrhea and bloody stools, and, if chronic, it is a risk factor for colorectal cancer. NF-ĸB proteins are potent players in UC progression. Their regulation remains a challenge due to their intracellular localization. siRNA-carrying calcium phosphate nanoparticles target the p65 subunit of NF-ĸB on site and thus achieve NF-ĸB suppression and a therapeutic effect in vivo. Objectives The goal was to synthesize calcium phosphate nanoparticles loaded with anti-p65 NF-ĸB siRNA, and to study their in vivo efficiency in NF-ĸB downregulation in an UC mouse model. Materials &amp; methods Calcium phosphate nanoparticles were stabilized with fluorescent polyethyleneimine (PEI-Dy734), loaded with anti-p65 NF-ĸB siRNA, purified and characterized in depth. The nanoparticles were injected intravenously into mice with DSS-induced UC or healthy ones (as control). In the studied animals we determined the UC features, the expression of NF-κB-associated proteins, pro-inflammatory local and systemic mediator secretion, and the organ leukocyte count in tissue sections. Furthermore, we performed NIR-studies on nanoparticle biodistribution. Results The nanoparticles were colloidally stable, efficiently loaded with therapeutic siRNA and met all quality criteria to be applied in in vivo studies. The nanoparticles effectively alleviated UC symptoms by suppressing the expression of NF-κB proteins in the colon. Consequently, they attenuated the secretion of pro-inflammatory mediators and the leukocyte load of spleen and mesenteric lymph nodes. The nanoparticle biodistribution in diseased animals was particularly strong in organs containing lymphoids. Conclusion siRNA-loaded calcium phosphate nanoparticles were effective in downregulating the symptoms of UC, and demonstrated biocompatibility and promising properties for the treatment of UC in the future.

Short Talks 17
Antimicrobials and Translation

Appointment

Chair

Topic

Programme

Short Talks 17Antimicrobials and Translation

Appointment

Chair

Topic

Programme

Short Talks 17
Antimicrobials and Translation