Laser Bioprinting of Cells Using UV and Visible Wavelengths: A Comparative DNA Damage Study.

Laser-based techniques for printing cells onto different substrates with high precision and resolution present unique opportunities for contributing to a wide range of biomedical applications, including tissue engineering. In this study, laser-induced forward transfer (LIFT) printing was employed to rapidly and accurately deposit patterns of cancer cells in a non-contact manner, using two different wavelengths, 532 and 355 nm. To evaluate the effect of LIFT on the printed cells, their growth and DNA damage profiles were assessed and evaluated quantitatively over several days. The damaging effect of LIFT-printing was thoroughly investigated, for the first time at a single cell level, by counting individual double strand breaks (DSB). Overall, we found that LIFT was able to safely print patterns of breast cancer cells with high viability with little or no heat or shear damage to the cells, as indicated by unperturbed growth and negligible gross DNA damage.

Laser-Induced Forward Transfer Printing on Microneedles for Transdermal Delivery of Gemcitabine.

Cancer treatment with chemotherapeutic drugs remains to be challenging to the physician due to limitations associated with lack of efficacy or high toxicities. Typically, chemotherapeutic drugs are administered intravenously, leading to high drug concentrations that drive efficacy but also lead to known side effects. Delivery of drugs through transdermal microneedles (MNs) has become an important alternative treatment approach. Such delivery options are well suited for chemotherapeutic drugs in which sustained levels would be desirable. In the context of developing a novel approach, laser-induced forward transfer (LIFT) was applied for bioprinting of gemcitabine (Gem) to coat polymethylmethacrylate MNs. Gem, a chemotherapeutic agent used to treat various types of cancer, is a good candidate for MN-assisted transdermal delivery to improve the pharmacokinetics of Gem while reducing efficiency limitations. LIFT bioprinting of Gem for coating of MNs with different drug amounts and successful transdermal delivery in mice is presented in this study. Our approach produced reproducible, accurate, and uniform coatings of the drug on MN arrays, and on in vivo transdermal application of the coated MNs in mice, dose-proportional concentrations of Gem in the plasma of mice was achieved. The developed approach may be extended to several chemotherapeutics and provide advantages for metronomic drug dosing.

Parametric Study of Jet/Droplet Formation Process during LIFT Printing of Living Cell-Laden Bioink.

Bioprinting offers great potential for the fabrication of three-dimensional living tissues by the precise layer-by-layer printing of biological materials, including living cells and cell-laden hydrogels. The laser-induced forward transfer (LIFT) of cell-laden bioinks is one of the most promising laser-printing technologies enabling biofabrication. However, for it to be a viable bioprinting technology, bioink printability must be carefully examined. In this study, we used a time-resolved imaging system to study the cell-laden bioink droplet formation process in terms of the droplet size, velocity, and traveling distance. For this purpose, the bioinks were prepared using breast cancer cells with different cell concentrations to evaluate the effect of the cell concentration on the droplet formation process and the survival of the cells after printing. These bioinks were compared with cell-free bioinks under the same printing conditions to understand the effect of the particle physical properties on the droplet formation procedure. The morphology of the printed droplets indicated that it is possible to print uniform droplets for a wide range of cell concentrations. Overall, it is concluded that the laser fluence and the distance of the donor-receiver substrates play an important role in the printing impingement type; consequently, a careful adjustment of these parameters can lead to high-quality printing.

Bioprinting for Liver Transplantation.

Bioprinting techniques can be used for the in vitro fabrication of functional complex bio-structures. Thus, extensive research is being carried on the use of various techniques for the development of 3D cellular structures. This article focuses on direct writing techniques commonly used for the fabrication of cell structures. Three different types of bioprinting techniques are depicted: Laser-based bioprinting, ink-jet bioprinting and extrusion bioprinting. Further on, a special reference is made to the use of the bioprinting techniques for the fabrication of 2D and 3D liver model structures and liver on chip platforms. The field of liver tissue engineering has been rapidly developed, and a wide range of materials can be used for building novel functional liver structures. The focus on liver is due to its importance as one of the most critical organs on which to test new pharmaceuticals, as it is involved in many metabolic and detoxification processes, and the toxicity of the liver is often the cause of drug rejection.

Phosphate Modified Screen Printed Electrodes by LIFT Treatment for Glucose Detection.

The design of new materials as active layers is important for electrochemical sensor and biosensor development. Among the techniques for the modification and functionalization of electrodes, the laser induced forward transfer (LIFT) has emerged as a powerful physisorption method for the deposition of various materials (even labile materials like enzymes) that results in intimate and stable contact with target surface. In this work, Pt, Au, and glassy carbon screen printed electrodes (SPEs) treated by LIFT with phosphate buffer have been characterized by scanning electron microscopy and atomic force microscopy to reveal a flattening effect of all surfaces. The electrochemical characterization by cyclic voltammetry shows significant differences depending on the electrode material. The electroactivity of Au is reduced while that of glassy carbon and Pt is greatly enhanced. In particular, the electrochemical behavior of a phosphate LIFT treated Pt showed a marked enrichment of hydrogen adsorbed layer, suggesting an elevated electrocatalytic activity towards glucose oxidation. When Pt electrodes modified in this way were used as an effective glucose sensor, a 1⁻10 mM linear response and a 10 µM detection limit were obtained. A possible role of phosphate that was securely immobilized on a Pt surface, as evidenced by XPS analysis, enhancing the glucose electrooxidation is discussed.