Author Archives: Hendrik Fiehn

MHTP-Thumbnail

Melt Electrowriting with BioScaffold Printer

Aug. 2018: Our customers at Monash University (AUS) successfully combined 3D printing of cell containing bioinks withs melt electro spun PolyCaproLactone Meshes.

For the future therapy of pelvic organ prolapse (POP) for womans they discovered eMSC cells in the endometrial lining of the uterus and and demonstrated their reparative capacity in tissue engineered constructs in a pre-clinical rat model.

For more information please ask.

TwinTip Thumbnail

TwinTip Adapter for the Nano-Plotter

Dec. 2017: The TwinTip adapter for the Nano-Plotter manages two (piezoelectric) nozzles for aspiration/ dispensing + mixing of tiny volumes.

It aspirates Microliter volumes of each sample from standard micro titer plates.

The adapter swivels both tips at a certain angle back and forth from aspiration position to dispense position. Read more…

Bellaseno_thumbnail

New Collaboration with BellaSeno GmbH, Leipzig

Aug 2017: We are proud to announce the collaboration with BellaSeno GmbH, Leipzig (D).

BellaSeno is a startup company commercialising many years of research work in the field of resorbable natural breast implants. In the future women suffering from breast cancer will no longer need silicone implants. BellaSeno is using the BioScaffold Printer BS3.1 to print personalized breast scaffolds made from PCL.

TwinTip – Pipetting and Mixing

TwinTip adapter for the Nano-Plotter

TwinTip adapter with two solenoid valve micro pipets

TwinTip adapter with two solenoid valve micro pipets

 

Chemical reactions at a microscale and hardening of two-component systems are just two applications for the new TwinTip adapter for the Nano-Plotter. In contradiction to other micro mixers the TwinTip adapter allows to aspirate tiny volumes of two different species from a standard micro well plate.

 

 

 

 

 

 

 

 

 

 

 

 

The TwinTip adapter accomodates the native GeSiM piezoelectric pipets as well as solenoid dispense valve pipets. Following setups are possible:

  • Two GeSiM piezoelectric pipets with drop volumes between 60 pL and 400 pL
  • Two solenoid valve pipets with droplet volume of 50 nL
  • One GeSiM pipet, one solenoid valve

The TwinTip adapter toggles the pipets between two positions: OPEN (Aspiration/ wash position) and CLOSE (Dispense position). Simultaneous drop release at the CLOSE position leads to a perfect mix up of both drops on the target surface due to the high kinetic energy of the drops.

 

Handling of the TwinTip adapter

Handling of the TwinTip adapter

Stroboscope view of collision of microdrops

Stroboscope view of collision of microdrops

Collision of Microdroplets

The Droplet Collider – Target, Hit, Merge…

Microdroplets ejected by the piezoelectric GeSiM dispensers fly at a speed of about 4 m/s. The high kinetic energy supports mixing of mixable liquids.

Piezoelectric Nanolitre Droplet Collider: Setup with temperature control unit and piezo driver (Left); Two heatable piezoelectric dispensers in front of a stroboscope unit (Right)

Piezoelectric Nanolitre Droplet Collider: Setup with temperature control unit and piezo driver (Left); Two heatable piezoelectric dispensers in front of a stroboscope camera (Right)

 

The GeSiM Droplet Collider is based on a manual swivel to host two piezoelectric microdispensers. Micrometer calipers allow to adjust position and angle of nozzles to make sure simultaneous ejected drops hit on air.

 

  • Stroboscope video of mixing process

    Stroboscope video of mixing process

    Stroboscope camera for visual alignment and drop inspection

  • Cartridge based sample delivery
  • Individual settings for both dispensers

 

Piston Extruders

3D Structures from Melted Thermoplastics

Our advanced motor driven piston extruders extend the capability of the pneumatic basic set:

 

  • High pressure (Virtually > 100 bar) prints viscoelastic and high-viscous materials, even with tiny nozzle diameters
  • Constant piston moves ensure constant material flow, independent on the material level inside the cartridge
High-Temperature extruder for thermoplasts

High-Temperature extruder for thermoplasts (Left); Pneumatic extruder (Right)

Gradient mixer for thermoplasts (Left); Piston extruder for hydrogels (Right)

Gradient mixer for thermoplasts (Left); Piston extruder for hydrogels (Right)

 

The High-Temperature Piston Extruder prints thermoplastics like PLA (Polylactic acid) at temperatures up to 250°C. It comes with the stainless steel cartridge as well as stainless steel nozzle. A two zone heater compensates the temperature drop from the cartridge to the nozzle.

 

The Gradient Mixer (Available for BS4.2 only) combines the outlet of two HT-Extruders with a special mixing head. It allows varying mixing ratios of two thermoplasts during one print.

 

 

Printing of larger volumes (50 mL) is available by the piston extruder for hydrogels.

 

 

PCL-PEG Blends for Tissue Engineering

Sequential Bioprinting with GeSiM Instruments

PCL (PolyCaproLactone) is a popular hard-phase biopolymer for tissue engineering and 3D printing. It is biocompatible and – to a certain extent – biodegradable. Multi-printhead instruments like the GeSiM BS31 easily combine PCL struts with cell friendly alginate/hydrogels.

Hard-phase biopolymers shall be optimized towards a quick degradation/mass loss when getting in contact with body fluid. An inherent drawback of pure PCL is the relatively high stability under physiological conditions. Here we present a recent study [1] addressing this problem. It was conducted using the predecessor of BS3.1, BS2.1.

 

PCL and polyethylene glycol (PEG) blends (PCL-PEG) together with alginate dialdehyde gelatine hydrogel (ADA-GEL) loaded with stromal cell line (ST2) were investigated.

 Scheme of a hard-soft phase scaffold with the hard thermoplastic phase (grey) and the soft hydrogel phase (yellow) containing the cells [1]

Scheme of a hard-soft phase scaffold with the hard thermoplastic phase (grey) and the soft hydrogel phase (yellow) containing the cells [1]

Stereomicroscope images of a plotted PCL-PEG (7030) scaffold as fabricated: topview (a); and side view (b) (scale bar = 2 mm) [1]

Stereomicroscope images of a plotted PCL-PEG (7030) scaffold as fabricated: topview (a); and side view (b) (scale bar = 2 mm) [1]

 

 

 

 

 

 

 

 

 

 

 

The PCL-PEG blends showed a much faster degradation and a mass loss tending to be almost equal with the corresponding content of PEG being ~14% for the PCL-PEG 8020 and ~23% for the PCL-PEG 7030 compositions. The wetting behaviour and the cell behaviour were improved in comparison to pure PCL. Blends showed improved hydrophilicity and cell response with PEG blending increasing the degradation and decreasing the mechanical properties of the scaffolds.

Fluorescence microscope images (a–f) of the actin cytoskeleton (red) and the cell nuclei (green) of ST2 cells in a PCL-PEG ADA-GEL construct after 28 days of incubation of different magnification: (a,b) overview images; (c) densely packed area of the cells covering both materials; (d) cell morphology on the hard phase; (e) cell agglomerate and spread single cells in hydrogel; and (f) densely packed area of cells (hydrogel phase) [1]

Fluorescence microscope images (a–f) of the actin cytoskeleton (red) and the cell nuclei (green) of ST2 cells in a PCL-PEG ADA-GEL construct after 28 days of incubation of different magnification: (a,b) overview images; (c) densely packed area of the cells covering both materials; (d) cell morphology on the hard phase; (e) cell agglomerate and spread single cells in hydrogel; and (f) densely packed area of cells (hydrogel phase) [1]


[1] Tobias Zehnder, Tim Freund, Merve Demir, Rainer Detsch and Aldo R. Boccaccini: Fabrication of Cell-Loaded Two-Phase 3D Constructs for Tissue Engineering, Materials 2016, 9(11), 887


 

Patient-specific Biodegradable Implants: The Future of Surgery?

Reconstruction of a Human Scaphoid Bone

The replacement of bones in course of accident treatment usually requires titanium implants. It is a widely used material for trauma surgery but shows inherent drawbacks: A mismatch of mechanical properties, interface issues to the surrounding soft tissues and no capability to grow.

 

A joint research project of GeSiM and Dresden University of Technology (TU Dresden) – Centre for Translational Bone, Joint and Soft Tissue Research – aimed in establishing 3D printing of patient-specific implants of a degradable biomaterial. As model the human scaphoid bone was selected and 3D data extracted from a CT scan.

 

1a) CT data set of human hand

1a) CT data set of human hand

1d) 3D model of scaphoid bone

1d) 3D model of scaphoid bone

1c) Segmentation of the scaphoid bone

1c) Segmentation of the scaphoid bone

1b) Bone extraction

1b) Bone extraction

 

 

In a first step the CT data of the patient were analysed to separate bones from the remaining tissue (Virtual environment/ contouring). Next the CT data was transformed into a 3D DICOM model using an Open Source software package. The scaphoid bone was isolated from the complete bone set to generate 3D STL data, a format describing surfaces by triangularization. The STL format is widely used by all kind of 3D printers, also the GeSiM BS3.1.

 

2) Scaphoid bone printed from bone cement [1], [2]

2) Scaphoid bone printed from bone cement [1], [2]

Finally the STL data of the scaphoid bone was loaded into the software of the GeSiM BS3.1. The bone model was printed from calcium phosphate bone cement VELOX® from InnoTERE GmbH, Radebeul.

 

This work is a research project without clinical background. Future research may be focusing on the settlement of osteoblasts or mesenchymal stem cells in the scaffold structure for subsequent incubation and generation of an artificial “living” bone.

 

We thank the BMWi for funding this work (AiF-ZIM program, project number KF2891602).


[1] T. Ahlfeld et al., Centre for Translational Bone, Joint and Soft Tissue Research, Technical University Dresden

 

[2] M. Heller, H.-K. Bauer, E. Goetze, M. Gielisch, I. T. Ozbolat, K. K. Moncal, E. Rizk, H. Seitz, M. Gelinsky, H. C. Schröder, X. H. Wang, W.E.G. Müller, B. Al-Nawas: Materials and Scaffolds in Medical 3D Printing and Bioprinting in the Context of Bone Regeneration. Int. J. Computerized Dent. 2016, 19, 301-321 (Figure 6)

 

Synthesis of Hydrogels

The Promise of Water containing Hydrogels

Hydrogels are widely used in regenerative medicine. The soft and water containing polymers are well appropriated as cell culture media but keep cells “in shape”: 3D printing arranges the hydrogel in a spatial manner or allows combined printing with other polymers.

In collaboration with the Leibniz Institute for Polymer Research Dresden a configuration for Hydrogel synthesis was developed. It starts with the conjugation of Polyethylene Glycol (PEG) with crysteine-containing peptides such that the conjugate contains a terminal thiol group. At the same time, heparin is coupled with reactive groups, all in an automated way. The PEG-peptide-thiol polymer is then linked to the heparin via a sulphur bridge, and other components (cells, adhesive peptides) are added. Star-hydrogels are possible.


The GeSiM BioScaffold printer is well appropriated for 3D prints with hydrogels. Please visit the related product site for BS3.1.